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Weather Flying

Weather Flying Robert N. Buck Robert O. Buck Fifth Edition

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Copyright © 2013 by Robert O. Buck. All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. ISBN: 978-0-07-179973-7 MHID: 0-07-179973-7 e-Book conversion by Cenveo Publisher Services Version 1.0 The material in this eBook also appears in the print version of this title: ISBN: 978-0-07-179972-0, MHID: 0-07-179972-9. McGraw-Hill Education eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. To contact a representative, please visit the Contact Us page at www.mhprofessional.com . All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. Information has been obtained by McGraw-Hill Education from sources believed to be reliable. However, because of the possibility of human or mechanical error by our sources, McGraw-Hill Education, or others, McGraw-Hill Education does not guarantee the accuracy, adequacy, or completeness of any information and is not responsible for any errors or omissions or the results obtained from the use of such information. TERMS OF USE This is a copyrighted work and McGraw-Hill Education and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill Education’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited.

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For Leighton Collins.

About the Authors

Robert N. Buck (1914–2007) was a leading aviation author who set a New York to Los Angeles speed record in 1930 at the age of 16. He began a career with TWA in 1937, initially flying the DC-2 and DC-3. During World War II he flew with the Air Transport Command, until as a civilian he headed a bad-weather research project for the U.S. Army Air Forces, flying a Boeing B-17 bomber; for this he was awarded the Air Medal. He also participated in early thunderstorm research, penetrating storms in a P-61 Black Widow. Post-war he was briefly TWA’s chief pilot, then returned to the cockpit to fly over 2,000 trans-Atlantic crossings, as well as served on numerous aviation committees on safety, weather, and U.S. supersonic transport efforts. He retired as a Boeing 747 captain, then remained active through aviation consulting, wrote four more books, and remained an active pilot until age 88.

Robert O. Buck is a retired Delta Air Lines captain, with roots in general aviation, where he remains an active pilot, flying light aircraft and sailplanes. He soloed gliders at 15 and a beloved Cessna 120 at 16, and retired flying Boeing 767s internationally. His aviation path has also included competitive soaring, flight instruction, aircraft sales, commuter airline flying, and serving as Technical

Editor for Business & Commercial Aviation magazine.

Contents About Some People Preface to the Fifth Edition Introduction to the First Edition 1. Weather Flying 2. A Little Theory for Weather Flying That Important Dewpoint How Air Cools Season and Time of Day Terrain Wind Clouds 3. Some Thoughts on Checking Weather It Isn’t Easy It’s Approved and Official How It Works You Are the Meteorologist You Are the Captain! 4. Checking Weather and the Big Picture The Big Picture No Surprises Satellites and Some NEXRAD What Do Satellites Show? Valid Old Map Thoughts Where We Find This Computerized Weather Get the Picture First On Days Off, Too A Deeper Look at the Map Watch the Slow Lows The Wind Speed Tells a Story Highs Are Not Always Nice Look Up A Meteorologist’s Big Picture from the Web 5. Getting That Weather Information

Always Learning Where and How Some Extra Sources No One Said It Was Easy Hired Help Opening Remarks to the FSS—and Ourselves Synoptic Again Look Ahead The Real Thing 6. Weather Details—What They Tell Us VFR—Not Easy MVFR MVFR Is Not Static IFR—Not to Worry Test the Forecast The Late Weather Regulations Aren’t the Important Criteria Pollution and Visibility How Do You Feel? More about Wind Altimeter Setting Temperature and Dewpoint Again PIREPs On the Ground, Too Summing Up 7. Checking Weather for the Route Weather Is Mostly Good Something on Fronts Occlusions and Zippers Large-Area Weather The Important Northeast Corner Go the Short Way It Takes Time to Know Why and If Don’t Fear Weather … … Or Worry about It 8. Equipment Needs for Weather Flying It’s Farther Than You Think Fuel and the Law

Fuel Again Instruments and Autopilots Where the Instruments Live We Can Keep It Simple A Little More to Do a Lot Things Can Be Better Even Better The Future Will Be Even Better The Protected Airplane Power for Instruments Lighted Well Paperwork and Gadgets Are Equipment, Too Go Fast Slowly Good Housekeeping An Extra Hand Navigation Radar and Lightning Detection Systems 9. Temperature, an Important Part of Weather Flying Temperature and Density We Better Figure It Out How Hot, How High? Engines Don’t Like It Hot 10. Some Psychology of Weather Flying Self-Discipline Think, for Real 11. Turbulence and Flying It Kinds of Turbulence How We Fly Turbulence Convective-Layer Turbulence It’s Rougher Than You Think Dust Devils Turbulence Near Mountains and Ridges Mountain Waves Turbulence Up High Where Is It? The Tropopause and CAT The Tropopause Is Important Shear

Where Is Shear? Thermals 12. VFR—Flying Weather Visually VFR The Famous 180 A Point to Remember Snow Is Different Keep Calm More Snow Towers VFR Navigation—and the Important Map Not Only Airports Where Is the Wind? Near Cities Summertime Thunderstorms and VFR VFR on Top Using Electronics When VFR Without Radio 13. About Keeping Proficient Flying Instruments Practice Self-Checking With Full Instruments 14. Thoughts on Flying Technically Advanced Aircraft Single-Pilot Operation in a Two-Pilot World Dependence on Augmented Indications Electronic Seduction Programming Thoughts Summary of Flying Basics in a Technically Advanced World 15. Thunderstorms and Flying Them What Are They? What Is Tough about a Thunderstorm? Tornadoes Hail The Bad Part Their Life Cycle A Clue

The Different Kinds How High? The Cloud Layers They Grow Fast What’s Inside All Those Clouds? What’s Outside All Those Clouds? Thunderstorm Detection Systems Airborne Radar NEXRAD Lightning Detection Systems Data-Linked Lightning Mapping Information ATC and Thunderstorms More about Air-Mass Thunderstorms A Cloud Base Hint Other Air-Mass Thunderstorms Dry Climate and Thunderstorms Frontal Thunderstorms The Surface Wind Tells How to Tell a Front’s Toughness Prefrontal Squall Lines Some Rules If We Fly Through At Night Where to Bore In How to Fly It Are We Scared? Something to Be Said for Rain Fly! Electrical Discharge Static and Radio The Noise Is Annoying Almost through the Storm Warm Front Thunderstorms Low Down Thunderstorms as We Arrive and Land Don’t Race Thunderstorms Missed Approach in Thunderstorms After the Missed Approach and Other Thoughts 16. Ice and Flying It About Ice Dealing with Ice

The Propeller Is Important Wing Deicers and Anti-Ice Boots Hot Wings Fluid Anti-Icing We Have to See How We Fly Ice Is Your Airplane Equipped to Fly Ice? Propellers, Jet Inlets, and Other Fixtures Ice Flying Starts on the Ground Where We Find Ice Temperature Again Where Are the Tops—and the Bottom? Fronts and Ice An Ice Airplane Not Always in Clouds on Instruments Warm Front Fishing to Get Out of Ice Taking Off in a Front Learning Time Orographic Effect Again Cold Front Flying to Feel Ice Coming Home 17. Taking Off in Bad Weather Altimeter Setting Be Prepared Let’s Go Radio Thoughts Don’t Be Bashful! Off We Go In the Stuff Quick How about the Weather? Once in the Air Thunderstorms Again Thinking 18. Weather Flying En Route Think Ahead What’s It Like? Forced Landing with Little Time to See

All Is Normal and It’s Time to Get There 19. Landing in Bad Weather Flying the Approach The Instrument Part Close in, Things Get Tight Stick with It When We See Again Autopilots Doing the Work Circling to Land To Touch the Ground Low Visibility Ground Fog On the Ground An Approach Briefing The Toughest Case 20. Teaching Yourself to Fly Weather Where’s the Emphasis? Learning the Weather 21. Something on Judgment Limitations Suggested Reading and Websites Acronyms and Contractions Index

About Some People There are many people to thank for helping me with this book. It starts with a meteorologist named Mr. Ball, who, when I was sixteen and starting across the United States alone, briefed me at Newark Airport, New Jersey, on what the weather would be. I was interested in what he said because I didn’t know much about weather, or flying either, and I was a little nervous. Mr. Ball—I never knew his first name—also awakened my interest in weather, what makes it, and what a pilot does about it. Looking back, I realized that Mr. Ball was an exceptionally good meteorologist. After Mr. Ball came a host of meteorologists, most of whose names I don’t know and never will. They are voices and faces over a telephone or in a weather office in some city when I was trying to make cross-country records, or just going somewhere. Some time later they were in wood-paneled rooms in Gander, Newfoundland, or Prestwick, Scotland, during World War II, when the Atlantic, sitting out there waiting to be crossed, was a big, black unknown, and whatever that man said I listened to carefully because any crumb of information was something to grab for help in doing a job that I didn’t know all there was to know about doing. There are meteorologists I got to know well by searching conversation as I tried to learn, and later in consultation as we probed the atmosphere in research— men like Ed Minser and J. A. Browne of TWA. I continued to learn from TWA meteorologists who briefed me on what the weather would be over the North Atlantic, which became an ocean I respected but felt very comfortable flying over in a 747. There is Nieut Lieurance (retired) of the National Oceanic and Atmospheric Administration (NOAA). Nieut is a pilot’s meteorologist and has done much to bring good weather services to us all. Chuck Lindsay (retired) of NOAA is one of the world’s foremost soaring meteorologists and a person always good for a new piece of knowledge. I thank Chuck also for reading the manuscript of the first edition and making some valuable suggestions. Lt. General Ira C. Eaker, a boyhood hero of mine, saw the possibilities of thunderstorm research and made it possible for TWA and the U.S. Army Air Forces* to work together using a P-61 Black Widow night fighter, which I was fortunate enough to fly in the project. Captain Robert A. Wittke, TWA (retired), my close friend since childhood, made useful and perceptive suggestions. Also, Dan Sowa, the superb meteorologist of Northwest Airlines, has given me many insights into the mysteries of weather, as has his associate, the brilliant technical airman, Captain Paul A. Soderlind of Northwest Airlines.

I’m indebted to my good friends at the National Weather Service in Burlington, Vermont, and the staff at the Flight Service Station in Burlington, Vermont. These men and women have been ready and most willing to patiently answer my questions and enthusiastically dig out information for me. I especially thank Ben Martin, Betty Czina, and Jimmy Mason of the FSS and William Grady of the Burlington NWS. Years ago, I learned from Dr. Horace Byers and for a brief but exciting and privileged time from Dr. Irving Langmuir. I wish I could name all the others, but there isn’t space. I do want it to be clear, however, that I thank all meteorologists. They are a misunderstood group who are cussed more than praised, when it should be the other way around. I want to thank Velma and Dwane Wallace for urging me to get this book done. Solid advice and encouragement came from Charles W. Ferguson and Caroline Rogers of The Reader’s Digest . They were patient and understanding friends. I must mention the man to whom this book is dedicated, Leighton Collins, who with his Air Facts magazine started me writing about weather almost 50 years ago. His enthusiasm and encouragement did the most. My wife Jean, daughter Ferris, and son Rob, captain on a major airline and an experienced weather pilot who shares my weather interest and study, all gave their enthusiastic support, and I thank them for that. Robert N. Buck Fayston, Vermont This version of About Some People is from Weather Flying ’s 4th edition (1998), and the last revision from the original author, Robert N. Buck (Bob Buck). Since then, a majority of the folks mentioned have left us, save for my (ROB) sister, myself, and the folks from the Burlington, Vermont, FSS and NWS. The Burlington FSS has closed as part of the FAA’s centralization of the FSS system, I have retired from Delta Air Lines, Northwest Airlines has merged with Delta Air Lines, and TWA became part of American Airlines. The weather, however, is still out there waiting for us.

* The United States Army Air Forces of World War II became the United States Air Force in 1947.

Preface to the Fifth Edition Crew Change In the late spring of 2010, my youngest son and I flew our single-engine Cessna 170 from Vermont to the West Coast and back, the trip a father and son adventure with a nostalgic twist. We retraced a good portion of my father’s 1930 record flight from New Jersey to California, his adventure flown in an open-cockpit Pitcairn biplane when he was just 16 years old. That daunting trip was my father’s first experience in blending aviation’s utility with weather, arguably sowing the seeds that blossomed into this book called Weather Flying . Our trip also traversed routes he had flown in TWA DC-2s and DC-3s, starting in 1937. We thought it interesting that our little airplane wasn’t that much slower than those Douglas transports and flew at the same altitudes. They battled ice, fog, turbulence, and harrowing thunderstorms, sometimes flying right through them, but obviously found good weather, too. We didn’t feel that historically compulsive, so took the good-weather route. Our trip also brought fond memories of years I’d spent flying with my father, both hanging out together, as well as cutting a wide swath through aviation’s field of dreams. He didn’t smother you with aviation, instead more along the lines of: “I’m going flying, and if you want to come along I’m leaving in an hour.” I was ready the moment he said it. If you flew enough with the guy who wrote Weather Flying , you soon learned this weather and flying relationship was a big deal. His enthusiasm for the fascinating riddle of weather was infectious, and one quickly learned that heeding it not only made flying work better, it also kept pilot and airplane safe to fly another day. Those years were the show-and-tell, lab-class version of Weather Flying . When this book made its debut in 1970, a lot had changed since those DC-3 days. It was the year my father checked out on TWA’s shiny new gentle giant, the 747. At the same time, I was working on a formal education that posed competitive quandary towards an obsession to flying, which included earning pilot ratings and building flight time. In four years my father would retire, and I was headed out into my own career. Eventually it would fortuitously find a forward window seat in an airliner, but not without holding fast to my general aviation roots. My career began about where my father’s ended, flying good old round-dialed analog airplanes, straight forward autopilots, and fair amounts of close-in hand flying, along with crafty pilots who skillfully mentored the tricks of trade. And then it began to change forever … our era was straddling the transition to today’s world of electronic flight instruments, programmed everything, and advanced automation. Some went kicking and screaming, but more importantly, when new

technology caused a quandary with an airplane and/or pilot, old-school flying sense provided the tools to think simply and use hand-flying basics, keeping us upright and aimed in proper direction, then fix it when all calmed down. It was nothing special; instead, just logical flow from what everyone was used to doing. This matching of eras was fortuitous when old flying dogs had to learn new tricks. It’s now been a generation since this technology has come along, and today we find both airlines and general aviation vying for the fanciest and newest technology of aircraft equipment; and with that, arguably, a developing over dependence on the technology. We see a gap developing between old-school thinking that brings airplanes home versus detached thinking, or lack of flying basics, that doesn’t. Not all the new dogs are learning old tricks. Whether they’re misunderstood, not being taught, ignored, or even more sobering becoming lost art, old-school flying thought and skills are being left out of the equation; and with that an unfair blaming of this superb new electronic world. From little airplane to big, flying high or low, privately or professionally, there are too many red flags and rustling leaves. Another twist of technology that blends into this book’s new edition relates to that all-important gathering of weather data, as we prepare our flights in today’s computerized world; it has become a lonely task. My son and I saw it on our cross-country journey, before leaving on a leg from St. Louis to Kansas City: we orchestrated the whole weather briefing on a smartphone. That was a first for us, and included the whole deal—weather data, maps, radar, winds, and more, then finally the phone call to a briefer for an update and to file a flight plan. I told my son there was once a time when you could walk into a weather office or Flight Service, talk with a briefer eye to eye, and have their knowledgeable assistance while looking over the data. Whether you were a new pilot or one with thousands of flying hours, it was a learning experience. Even granddad, I told him, who understood weather as well as anyone, relished the opportunity. My son’s quick mind of youth realized that meant today’s pilots better know this weather thing cold; especially after he saw that flashing, seething mass of thunderstorms half way to Kansas City, as we turned left and diverted to Wichita. When the opportunity came along to revise this sage text, my primary task was not to mess with the book’s core, whose respected story of 43 years tells us how to fly weather with practical understanding. My father had a knack for telling a story with concise and comfortable simplicity, and frankly that’s how we should think about flying. If there is any doubt of this seasoned book’s currency, we need to remember that the sciences of weather and how airplanes fly have remained the same since time began, as is the science of bringing the two together. And it’s still the same stuff even if masked by sleek, powerful airplanes with magnificent electronics. One of my father’s memorable comments was something to the effect of: “Folks jump into equipment they aren’t ready for, depend on the gadgets to pull

them through, then take off and get in over their heads.” It’s obvious what can happen next. He said that decades ago, but the same unnecessary endings are being repeated today. These fantastic modern electronics are perfect for serious weather flying, and a majority use them well, but the equipment also puts us in the professional realm of more study and practice. Today, the task of managing the airplane, pilot and weather is a new ballgame! So this edition’s new writings connect Weather Flying with today’s world of computerized and electronic weather data and aircraft equipment. We also found a few new twists in weather science, but again, working to retain the book’s respected core. This edition does not tell us how to operate every little button or computerized application. Instead, there’s discussion on how we merge this technology into our weather planning, then once airborne, use electronics prudently, while blending the whole process with disciplined thought and flying basics; including a higher bar of training. And very important is not misusing technology as a replacement for a pilot’s ability or knowledge. On the bright side of flight, as my son and I roared along behind our Continental engine’s six little cylinders, part of my job was placing my father’s stories into context and in some cases, over almost exact locations. We pondered his explanation of how he survived flying across the country at age 16, with only 97 hours in his logbook and in a far less air-savvy era; but his generation lived with basic sense! He said the key was being taught how to fly well, practice, improve, think, and not push the weather. It’s still that simple today, almost a century from those early days of aviation! When my father flew weather research during WWII, he had a plan and limits; maybe not ours, but certainly his and the airplane’s. I also told my son that his grandfather was one of the most conservative pilots I’d known, especially considering his credentials. And remember the thought of flying at DC-3 speeds and altitudes? Well, that’s where most general aviation aircraft still fly, and a little turbocharging or turboprop performance has us up there with the B-17 bomber and P-61 Black Widow my father used in weather research, with the same turbulence, ice, thunderstorms, and other meteorological angst, but also the same beautiful sky. So, when you read Weather Flying’ s references to lessons learned in DC-3s, the B-17, and later craft, we’re still pretty much in the same corral. The weather sure doesn’t know the difference, nor do aerodynamics! With the little stories throughout the book, you’ll see a little “RNB” for my father’s yarns, and “ROB” for mine. We should remember his era’s stories were from flying into the unknown and figuring out how to make it work, while my stores reflect our era, which benefits most from heeding the lessons they offer us. We also encourage reading Wolfgang Langewiesche’s Introduction to the First Edition , a few pages on, where you’ll find more of the story that led to this book’s original core; with Mr. Langewiesche’s career and writings a fascinating

and learned endeavor well worth seeking. It’s been about two generations since Weather Flying first came out, and since then the pioneers and era from which it’s writings came are no longer with us. With this, the needed old core is only available from disciples or the written word. We hope this book’s original writings bring some of that written word, while the new words link us to it. And these new words are not mine as claimed source; instead I’m reporting the learning’s and lessons from countless clever folks in this flying business. The sky is a wonderful and fascinating place, and we hope Weather Flying is helpful companion to your hours aloft, treasured as much as ours have been.

Acknowledgments When you read my father’s comments in About Some People , you’ll have a glimpse at some fascinating personalities who helped shape aviation. I’d like to elaborate the story of Leighton Collins, to whom this book has always been dedicated, and his magazine Air Facts . Leighton’s devotion to general aviation and its safety, as well as his quality of aviation journalism, remains the high standard for today. The magazine was written not only in-house, but also by most anyone who wanted to contribute; a gift of forum for aviation. The diversity of articles and range of knowledge for all aviation was phenomenal. Air Facts also gave a foothold and encouragement to much of my father’s writing, which ultimately led to Weather Flying , with four more titles after this one. Air Facts also provided a home for the literary efforts of many young aviation enthusiasts, including myself. Leighton Collins’ influence, for the industry and to me personally, has been an immeasurable gift. So, in switching generations, I thank Richard Collins, who’s encouragement and helpful input toward revising Weather Flying were greatly appreciated, both professionally and personally. I’d like to also recognize Richard’s devoted career in general aviation, where he has mentored multiple generations and eras toward a safer path. His skilled and experienced writings encourages us all to process the important task of learning about weather and flying it carefully, especially as he always has—a pro. And Air Facts is now back with us electronically, again of superbly diverse content both in-house and from the enthusiasts, as www.airfactsjournal.com . In the beginning of the project, Jeff Newman offered helpful guidance that brought me out of the cold as to the publishing world, as well as sage words towards taking on the task of family scribe. Archie Trammell, of airborne weather radar school fame, and longtime aviation journalist from whom we’ve all been fortunate to learn, offered generous support and data towards revising Weather Flying . While editor of Business and Commercial Aviation Magazine , he was my boss and patient mentor as I served

as a technical editor. George Larson, aviation journalist, pilot and long-experienced editor, whose superb and diverse writings over decades has brought enthusiasm to so many of us who love aviation, kindly offered sage words from both the literary and personal ranks, as well as calming support during moments of angst. Bruce Landsberg, President of the Aircraft Owners and Pilots Association (AOPA) Foundation, shared his thoughts about revising the book in the context of today’s diverse world of general aviation technology, operations, and safety concerns. His constant concern and efforts towards general aviation is generously devoted and important. We’re indebted to John and Dick Roberti’s Vermont Flying Service, including Steve Skinner—maintenance, and Wayne Chase—instructor, and all the gang of aviators that make it a fine flying home. They have supported and made possible our family flying for decades, even in cold Vermont winters. They, as well as their wonderful parents Edmando and Mary, have offered input and support to four editions of Weather Flying , and other family writings. Einar Enevoldson offered valuable input on flight instrumentation, from his wealth of aviation experience as engineer, NASA and industry test-pilot, recordholder and now as founder and chairman of The Perlan Project—high-altitude sailplane program. His modest brilliance is a generous treasure to aviation. Andy Nash, John Goff, and Eric Evenson of the National Weather Service office in Burlington, Vermont, were an invaluable resource on wending through today’s superb and extensive sources of weather information and application. They also continued the kind tradition of NWS-Burlington offering invaluable assistance to many family publications. National Weather Service meteorologist Dan Gudgel, offered suggestions of concept to this book’s direction, both personally and through his diverse writings on weather and the National Weather Service in Soaring Magazine . Steve Caisse shared his airline dispatching and meteorology expertise, especially in an operational sense. Meteorologists Steve Stock, Fred Brennan, and Erik Wildgrube offered valuable insights on modern weather information dissemination and application. Local Vermont meteorologist Roger Hill made available his broad reach of weather knowledge, especially in the area of climatology. His website (www.weatheringheights.com ) is an interesting and unique resource. Dr. Ralph Markson, scientist and aviator, generously shared his long and determined years of research on, among other phenomena, thunderstorms and lightning, aiming me down a better path in offering the subject to you, the reader. Dr. John Hansman, who brings to aeronautics a wonderful blend of academic prowess and classic stick-and-rudder pilot skills, from sport aviation to flight test and research, offered helpful insight into timely icing and weather data issues, as well as related operational inputs.

Captain Douglas Smith, Delta Air Lines (retired), whose career-long enthusiasm as aviator, flight instructor, and author has given his high-quality of example to the new and seasoned pilot alike, found time to kindly share his support and many valuable thoughts to this project. As founder of Vermont Flight Academy, he made available their facilities and personnel to assist in revising Weather Flying , including providing the simulator pictures, which Tyler Brown organized and is our enthusiastic pilot at the desktop trainer. Captain Monty Sullivan, Chief Pilot for Corning Incorporated, offered valuable insights into the professional world of corporate aviation and its operations, especially as to advanced aircraft and avionics. Captain Steve Green, from his extensive involvement with aircraft icing research, accident investigation, and operational awareness, offered helpful updates regarding icing and related operational concerns, as well as generous readings and critiques to portions of this work. Captain David Kloss was especially helpful with instrumentation concepts and operation, drawing on his engineering background as well as extensive involvement with general aviation and airline flying, including years of instructing. His reading of the text and sage comments were invaluable. Captains Mark Shepard and Neil Muxworthy provided an opportune look at advanced simulation and also offered helpful input to operational aspects of today’s state of aircraft automation. Longtime friend Bob Bowden, who defines the words “a natural pilot” and thinks better and more sensibly about aviation than any of us, was continually helpful in keeping this book’s revision in touch with core flying sense. Captain Gordon Boettger, who shared his first-hand skills and knowledge with high-altitude and long-distance wave-soaring. His picture, Looking North , which he generously provided for the turbulence chapter, brings us the sky’s power and beauty from a rare perspective. Russell Kelsea, from his years of experience in general aviation, offered great suggestions on merging automation and flying basics. Paul Gaines, with his business of Composite Solutions, offered consult from his extensive experience in composite aircraft repair and performance enhancement, on current general aviation composite aircraft design and structures. Of the National Soaring Museum in Elmira, New York, museum director Peter Smith and marketing director Ron Ogden, assisted in archival research and obtaining current copy of the Robert Symons Sierra Wave picture. The museum is valuable resource and excellent display of soaring’s fascinating and important history. Dr. Graham Ramsden, good friend, professor, and fellow soaring enthusiast, shared his academic suggestions on plodding through the project, including tenacity of the effort. Ryan Oshea gave valuable input, taking time to read part of the text and

offering his experienced input. Kitty Werner helped immensely in various text and editorial tasks, as well as continued a tradition by having assisted my father in his writing tasks. Thank you, Ky Copeland, for always having the answer to my numerous computer quandaries. My appreciation to all the folks out there who I may have embarrassingly missed or with whom I’ve shared this flying business, either in person or during thousands of hours together in the sky. They have given their mentorship, encouragement, hints, flat criticism, patience, professionalism, and yes, the great wit and humor that permeate aviation. One is fortunate to share such a great world, with memories that last for a lifetime. I’m very thankful for McGraw-Hill Senior Editor Larry Hager, whose kind soul encouraged keeping the book in the family and allowed my unpracticed willingness to take on this project. Larry, along with his assistant Bridget Thoreson, bore the brunt of my learning curve in this large writing task. Then, finally, it was a pleasure working with Sheena Uprety and her team through copy editing to the book’s production. I have to admit flying airplanes for a living is a heck of a lot easier. My wife Holly, daughter Heather, and sons Aaron, Todd, and Christian offered support of task, suggestions, and patience as I orbited in moments of angst and frustration. In the last throes of the project, Christian’s well-timed college vacation and computer wizardry allowed him to bring illustrations into usable format and helped firm up the text, as did Aaron’s reading through part of the manuscript, his suggestions helpful from his honed writing talent. My sister Ferris and her family were always supportive of my life in the clouds, interested in where it was going next and understanding when it became complex. Ferris also offered her fine input to the writing task, along with many memories and reminders of our lives growing up around the aviation world. To my folks, Bob and Jean Buck. We again remember this opportunity of revising Weather Flying was because my father wrote it in the first place—his words are the ones that make it valid. When drawn into aviation’s spell at a very young age, my parents encouraged prudently, and supported kindly. My father usually mentored subtly and in intriguing ways. My mother coped patiently while I was a young teenager but well into solo flight, her boys wandering the skies, and at times not without complex father and son issues. She was always center of home and patience. Robert O. Buck Waterbury Center, Vermont

Introduction to the First Edition What Captain Robert Buck says in Weather Flying has not been said before. Other books explain how weather is made; this book explains how weather is flown. We get to the field in the morning. Here is the weather: the map, the forecasts, the sequence of current reports from many points, the winds aloft—the whole package, prepared by experts. However deep our knowledge of meteorology may be, we cannot hope to do better. For us as pilots, the question is: What do I do with this? Go or no go? If go: go underneath the weather, or on top, or through? Or go around it? Follow a railroad? File an instrument flight plan? Go right away? Delay a couple of hours? Those questions; they are the last of the real problems of flying. Everything else has now been quite well mastered. The airplane itself now works: it handles nicely (at least, those flown by the general public). It has climb to spare, and we can usually find some level where the air is smooth. Noise and vibration are subdued: we can stand long hours in a day and make big distances. Electronics tell us where we are. Airports are plentiful and runways long. Engine failure is so rare we now almost forget about it. Even the economics of flying are no longer so forbidding. But the weather … It is not often clearly impossible. When it is, we have no problem: back to the hotel. On the contrary (as Captain Buck points out), the weather is normally flyable. Again, no problem, or only easy ones. But every once in a while— depending on season and part of the world—something is sitting out there that worries us. If you fly far enough in a straight line, you’re likely to come up against some problem weather that very day. How well we deal with those situations determines how well the airplane works. Too bold, and we cause emergencies and have accidents. Too timid, and we destroy the utility of the airplane and let our skill as pilots atrophy. Then pretty soon we have to be more timid still. These weather decisions can be painful to make, because we don’t really know how to go about making them. And we know we don’t know! We make them often by a process which is a dumb, confused struggle between “guts” and “judgment,” ambition and fear. How it comes out depends on how we felt that day when we last had a good scare, whether the girlfriend is looking, or “This town is full, there is a convention on, you can’t get a hotel room, let’s go.” Things like that tip the balance. And so (in Buck’s words) we “drag the luggage back to town,” often for no reasoned cause, or we “fling ourselves into the air,” often with only a vague estimate of what’s ahead. Or else, more likely, we stand around for another hour, look at the weather map some more, wait for the next weather sequence to come on the teletype, and think, “I wish I could talk this over with

some really experienced friend.” That’s where Bob Buck comes in. Experienced? We could consider 2,000 hours quite a respectable lot of time. Buck has some 2,000 Atlantic crossings! And those are only half of his experience. At this writing, Captain Buck’s log records well over 29,000 hours, all types. He set his first record when he was 16, in a Pitcairn Mailwing, an opencockpit biplane. It was the Junior Transcontinental Record, New York to Los Angeles, and “It didn’t amount to much—mostly just getting there.” He set another record, for nonstop distance in light airplanes, in a 90-horsepower Monocoupe, overnight from California to Ohio—his engine quit there. With the same airplane he joined an expedition and searched the jungle of Yucatan for Maya ruins. He joined TWA as a copilot at the time when the DC-2 was the Giant Airliner, then the DC-3. In those ships, between Pittsburgh and Newark, on a winter night, a pilot could learn a lot about flying the weather. It was about the toughest weather flying ever done. Instrument flying was new then. Radio aids and instruments were still quite crude, airplanes comparable in performance to present-day private airplanes. But the airlines flew almost the same weather as now. TWA had a milk run from Kansas City to Newark that took all night and made nine stops, and some nights all nine required an instrument approach. TWA made Bob Buck a captain in two years. Then the war came, and the first great surge of ocean flying, in four-engined land planes, under the aegis of Air Transport Command. Buck became Assistant Director of Training for TWA’s Intercontinental Division (which was part and parcel of Air Transport Command). He checked people out on the DC-4s and on the ocean routes. Next, for four years, he was the captain and manager of a special research project that TWA had taken on for the Army Air Forces. He had a B-17 bomber (“Flying Fortress”) to himself and a mission to seek out precisely the kind of weather that others stayed away from—the kind that gave the most trouble. It started with research into snow static —the kind you find best in Alaska. Icing research was added, then other things; before long, he was carrying 14 different projects. To find enough weather that was bad enough, Buck ranged from Alaska to Panama, out to Hawaii, to Southeast Asia, and, once, clear around the world. He ended up doing outright thunderstorm research. For this, they gave him a P-61 twin-engined fighter (the “Black Widow”) with lots of radar and lots of structural strength. He flew thunderstorms forward and backward, slow and fast, high and low. What was inside the monsters? Could you get through without spilling your gyros? How much did you dare slow up the airplane? What was the best way to keep control of the airplane? How bad was lightning, hail, turbulence? It was one of the first deliberate, systematic series of flights through thunderstorms ever undertaken. Buck then went back on the line, but kept doing new flight research for the military and the airlines both—on airborne radar and on low , low instrument approaches. When the Instrument Landing System first came in, he was one of

those who had to figure out the best way to use it. Once he wanted to study runway visibility in fog as it appears to a pilot breaking out of a low overcast. He let himself be hoisted up into the overcast, hanging in a parachute harness from a captive balloon. He likes to fly. He likes that left-hand front seat of an airplane. At one time they made him chief pilot of TWA. He found that the desk work interfered with flying, and he quit and went back on the line as a captain. “The sky is my office,” he once wrote. He was again tapped for the executive side of the company. TWA’s president at the time talked to him about it and held out the prospect of a vice-presidency. Buck said: “Mr. Burgess, there are only two jobs on this airline I would want—yours or mine.” He owns a high-performance sailplane, which he flies in cross-country competition. He once made a private tour of Africa in a DC-3. He has been around the world once sidewise—i.e., via both poles. He sits on various national and international committees that deal with piloting, is active in the Air Line Pilots Association, and acts as a consultant to manufacturers of airplanes and electronics. But always, when you see him again, he is just back from Paris or Bombay, with a cabinful of passengers riding behind him. So that’s the man who now comes in, as we stand there studying the weather map and debating what to do. He knows our problem. We are not engaged in an academic exercise: We are making, or passing up, a serious commitment. As we search the weather map, we are also searching our souls: Am I good enough for this? Can I hack it? On paper, this weather situation can be dealt with by suchand-such a procedure. In reality, when the pressure comes on, will I get flustered and panicky, so that I can’t do my best? Airplanes are flown in weather by real people, and the pilots—we, ourselves—are part of the situation. Buck himself has been through enough tense situations to—well, to write a book. He’s seen fellows’ knuckles turn white on the controls—and maybe sometimes his own. There are some interesting short passages in his book where he touches on that side—panic control, self-control, the constructive use of the imagination. You can keep an easy touch on the control, he says, even though your knees are shaking. These passages will convey a little of the man who is talking to us—his air of ease, cultivated by long self-training and mental discipline. They will also give you the impression that he is your friend. It’s interesting to note here some things he does not say. He does not bore us, for example, with the phony good advice, “Don’t exceed your limitations …” We do not know exactly what our limitations are. You don’t know the breaking strength of a material until you have broken it. Nor do we know how tough this particular weather situation will be to fly. That’s just our problem! And he does not come at us with an advanced course in meteorology. Certainly it helps, in flying the weather, to know some textbook meteorology, to have clear concepts of the things we meet in the air: cold fronts and warm fronts,

cumulus clouds and thunderstorms, inversions, dewpoint and temperature, and types of fog, the principal air masses in our part of the world. This knowledge helps us understand the language of the weather-person and the meaning of the weather map. And it helps us to recognize these weather phenomena when we meet them. The nature of the brain is such that we see what we have seen before, and what we have a name for. We are blind to things which have not been properly introduced. People had fronts passing over them for thousands of years, but nobody ever saw a front as front —i.e., as boundary between contrasting air masses. Then, 50 years ago, the Norwegians first recognized the cold front , described it, and named it. Now everybody can plainly see many frontal passages every year. In this sense, some descriptive meteorology helps the pilot fly the weather. But with the pilot’s main problem—What do I do?— textbook meteorology helps only little. And just because it helps so little, we are tempted to give him more—more than he has any use for: to go deep into the question of how weather is made. The coriolis force, the geostrophic wind, the latent heat of condensation, the adiabatic lapse rate, frontogenesis and frontolysis. All that is a fascinating look into God’s kitchen, but the pilot does not want to make the weather—or even the forecast. All he wants to do is fly it. And for that he does not need more meteorology; he needs a different kind, and he is getting it here. What is it Captain Buck does for us? It’s like untying a knot. The bafflement we feel as we try to judge a weather situation is a sort of knot in which everything is balled together. Weather. He shows us where to find the place to start and how to unravel it. Read what he says about the big picture, the If-Thinking, and Way Out, and right away the problem takes on order. These are indeed things on which we can ask questions, find the information, and make judgment. Perspectives open, a strategy suggests itself. More questions follow. What will be the influence of the local terrain, the time of day? You feed that in, and you can make more judgments. Now you have more to judge by: This mountain range is okay now but probably will have many thunderstorms in the afternoon. Better go now. This city with this wind direction will have industrial smoke in the morning, but visibility will improve by noon; you gain by delay. And so on. By showing us what the productive questions are, Captain Buck arms us with a judgment capability we never knew we had. Another problem that baffles us: how to monitor the weather once we are en route. The weather here and now is okay. But where I’m going it is different, and by the time I get there it will be different again. Is the situation solid? Should I do something or just keep flying? How can I know? Sure, we can get weather information by radio. But the same old problem: What is the intelligent question to ask? And what do we do with the information? Should we do anything? Many of us find it difficult to get an effective thought process started. We just keep on flying and hope the weather will hold. Buck

reminds us that a whole weather system may not move as fast as “they” expect, or may move faster or may even back up. This is perhaps the most frequent reason for forecasts going sour. He thereby gives us another productive question to ask: Is the weather system moving as expected? Now that we see the question, we can often get the answer we need by watching (for example, the progress of a cold front) at points that may be quite far off to the side of our route. It’s really a quite simple idea. It’s just a sample the captain gives us of what goes on in his mind when he is captain. But it greatly smartens us up. Bob Buck writes as he talks and flies, with an easy touch. He uses small words. Unlike most professionals, he does not try to make his art seem mysterious and difficult: He makes it seem simple and plain. This might fool some reader into thinking that he is getting just a light chat. Not so. What we get here is in reality a sophisticated course in problem solving. Buck shows us not what to think but how to think. Not “What should I do?” but “How do I go about deciding what to do?” Rules never quite fit the real-life situation. But a man who acts on rational grounds and knows what his reasons are can deal with the variety of real-life situations realistically. And should things not work out as expected, should the judgments have been mistaken or the information false, such a man discovers his error early, while he still can do something about it. Rational decision making: In business or government, we call this the Harvard Business School Approach. It is an American specialty, and it has been immensely productive. It will be productive for readers of this book. Because of this sophisticated approach, Bob Buck’s book is equally useful to pilots of all experience levels. All pilots do not fly the same degree of weather. Many people have to fly Visual Flight Rules (VFR); some fly instruments. Many have to be cautious; some can fly tough. But all have much the same problem of decision making—the problem the captain shows us how to solve. And so, this book being about this sort of thing, and written by this sort of man, a pilot needs an introduction to it like a hungry man needs an introduction to a steak. Just start right in. Wolfgang Langewiesche Princeton, New Jersey 1970

1 Weather Flying Weather bothers our flying in only a few basic ways: it prevents us from seeing; it bounces us around to the extent that it may be difficult to keep the airplane under control and in one piece; and ice, wind, or large temperature variations may reduce the airplane’s performance to a serious degree. That’s what weather does. There are degrees and nuances, but all in all, we fight weather in order to see, keep the airplane under control, and to get the best and safest performance from an aircraft. The question is, “How?” Well, we should know something about weather, what it is made of, and how it moves. But a pilot wants to know practical things: what to do about the weather and how to cope with its capriciousness. These practical things are a philosophy for thinking about weather and methods of flying it. Prior to developing a philosophy and methods, a pilot should have one point firmly etched in mind: weather forecasting is not an exact science. This statement is an old one, but it’s true and ought to be thought about before tossing it aside as old hat. The best weatherperson or an impersonal computer cannot forecast with perfect accuracy. The National Weather Service can make impressive statements about how well they do, and their numbers are valid and true. In the overall picture, they do a good job, percentage-wise; but the time they miss and pull their accuracy down from 100 percent to something even a little less may happen to be the night our destination was forecast clear, but fell on its face to zero-zero! Right then, the pilot isn’t much interested in statistics—except in trying not to become one. This shouldn’t be taken as criticism of meteorologists or computers. Actually, a compassionate, understanding, and friendly feeling toward them will do the most good, but understand the cold fact: you cannot count on weather always doing what is forecast, because even with fancy computer models, satellites, and perhaps a little witchcraft, we simply cannot outguess it 100 percent of the time. This means there will be times when the weather is not as forecast, when it will be bad rather than good. This is a fact of flying life, and we must always be prepared for it, accepting this as part of the game, ready to cope with it coolly and free of emotion. And that is the most important statement in the book! The pilot’s weather philosophy has two parts. The first is skepticism. Being a weather skeptic is an important ingredient of the formula for living to a ripe old age. The second part is always to have an alternate plan of action. These two

keys, skepticism and alternate action, are the foundation of it all. Being a skeptic keeps us safe; having an alternate plan of action adds to safety, but more importantly, it makes it possible to fly and to make the airplane work. If we are completely skeptical, we put the airplane in the hangar and forget about it, and sometimes this is a good idea. But we are trying to use airplanes; we want to go places as much as possible. The alternate plan of action helps us to do so. Say a pilot is headed for a place that’s forecast clear; skepticism says it’s near the coast, night is approaching, the temperature is near the dewpoint, and the wind from the sea—our destination airport could fog in. Now the easiest way out would be to stay home. However, we can also take off and probably make it, as long as there is enough fuel to get away from the coast, should it fog in, and fly back inland to a fog-free airport. That’s alternate action. That is a very simple example, but it is basic and important. It is the way airlines operate and the way they keep going. They are skeptical about weather— skeptical enough to have an alternate plan of action for everything they do. To fly in weather, a pilot needs certain abilities and various degrees of equipment. Since all pilots cannot have all the ability and all the equipment, they must take on weather in amounts that fit their levels of ability and equipment. This can be done, and the fact that a pilot doesn’t have instruments, radio, and a rating to use them doesn’t mean he or she has to stay on the ground whenever there is a cloud in the sky. However, it does mean that pilots must realize their limitations. There is a point of confusion in this area that gets people in trouble: the mistaken idea that equipment makes up for lack of ability. A pilot can have an airplane with all the trinkets, bright and new, up to par and working well, but if that pilot doesn’t know how to use them, and how to go back and manage with just basic instruments should the fancy stuff fail, that pilot is worse off than a pilot with nothing more than engine instruments and a compass. These issues are exponentially and dramatically magnified in today’s world of automation and technically advanced aircrafts. Remember, despite the most sophisticated equipment available, big airplane or small, it is not possible to fly all the weather conditions Mother Nature can create! What all this means is that pilots must know and fly by their limitations. All pilots, even 40,000-hour professional pilots, have them. What we are going to do in this book is talk about flying the weather. We will talk about weather in the meteorological sense and then about how we approach the weather problem and what to do about it. We will also talk about pilots’ emotions and thoughts when they find themselves, say, in the middle of a thunderstorm. There are things to talk about, such as instrument flying techniques and how

to test yourself to get an idea of your limitations. There are matters of technique and philosophy for the person who doesn’t fly instruments. One of aviation’s greatest fascinations is the weather. When it’s bad, it consumes our flying thoughts, but we think about it, too, on a sunny, clear day with a light wind and pleasant temperatures, if for no other reason than we must say: “What a beautiful day to fly, but I wonder if it will stay this way.” Weather has so many facets that we never stop learning about it. Personally, with more than 80 years of combined flying, it has taught us for certain that one can never definitely say that the situation is guaranteed, knowing exactly what will happen. We learn to respect weather and never to be complacent about it. This is the warm kind of respect we give to a beloved adversary, for after all, weather gives us many things: green grass, a blue sky with fluffy white clouds, and the rush of a summer storm that thrills and excites us. It gives the cool, soft kiss of gently falling snow, and the beautiful following day when the front has passed, offering gifts of sparkling sunshine and crisp, invigorating air. Like a good friend, weather rarely bores us; it supplies constant variety for our lives. How dull it would be, on the ground or in the air, if we never had to ask, “What’s the weather going to be?”

2 A Little Theory for Weather Flying Most books on weather start out by saying that air is made up of 21 percent oxygen, 78 percent nitrogen, and 1 percent other gases. This isn’t that kind of book, and instead we might say that air is made up of wind, turbulence, clouds, precipitation, some fog, and a lot of nice, clear days. But we cannot escape all the theory and must talk about some of it. You will find lots of things said more than once in this book. This is because many weather factors apply to more than one weather condition and will automatically be repeated as different types of weather and flying are discussed. And lots of points are purposely repeated to be extra sure we understand their importance. Weather is complicated. A deep study of the science shows many complex factors, but when you boil it all down, the keys are temperature and moisture; visible (precipitation or cloud) or invisible (vapor). Basically, there is always a certain amount of water vapor in the air, and when air is cooled, this water vapor is squeezed out and made visible. Much of meteorological study revolves around the ways water vapor can bother us, and what processes there are to cool the air enough to make that water vapor visible.

That Important Dewpoint There are a couple of items that pilots should know. One is dewpoint. Most of us know it as the temperature at which condensation begins. If the temperature is 15 degrees C 1 and the dewpoint is 13 degrees C, we have only to cool the air 2 degrees for the moisture to come out where we can see it … and if it’s fog, that’s all we can see. Dewpoint is handy for a pilot. It’s on the weather sequence reports, and it is a simple matter to look at the temperature-dewpoint pair and decide what the chances are that they will come together. That is a matter of deduction and common sense. If night is approaching, the temperature is going down; if there’s a body of water, with a wind blowing from it toward the land, the dewpoint is going to go up, giving the same effect as lowering temperature. If it’s early morning, it is obvious that the sun will come up and heat the air, separating the temperature and dewpoint. A little warning, however: Sometimes fog doesn’t form until the sun comes up. An airport may have the same dewpoint and temperature during a still night

and yet not fog in. Then, just as the sun is coming up and we think everything will be okay, the airport goes zero-zero. The reason for this phenomenon is that formation of fog requires some turbulence. We know that fog feels still, and one would bet there wasn’t any turbulence, but there is enough to mix the air and give the fog depth; if there were no turbulence, with the dewpoint and temperature the same, we would only get dew on the grass (hence the name dewpoint), and not the fog. As the sun rises, however, on the rare occasion when the air is dead still, there is a delicate period when the air begins to stir, creating slight turbulence before its heating is sufficient to raise the temperature. With this sensitive setup, fog may form suddenly; it’s like the situation of ice not freezing in a bucket of water with the temperature below freezing, until the water is disturbed. Ground fog will generally burn off with heat from the sun. This burn off, however, will take longer in winter, especially at high latitudes, and if there’s an overcast above reducing the sun’s heat, the fog may never burn off. While stewing on the ground waiting for ground fog to go away, we can contact weather sources, either through electronic access or by calling the Flight Service Station (FSS), looking for pilot reports (PIREPs) to see whether a higher overcast exists. If it does, we’ll have a longer wait for the fog to dissipate. If rain begins falling from a front, it will raise the dewpoint, and if night is approaching, it will lower the temperature; thus, both temperature and dewpoint are working to get together and make it a miserable evening. There are many combinations that bring these two together, and in most cases it doesn’t take a scientist to figure them out. The temperature–dewpoint relationship is a key guide to weather flying, one which pilots should always keep right up front and current.

How Air Cools We should also review how air gets cooler. The simplest way is by the sun going down. As we discover at an early age, it gets cooler at night. This type of cooling is called “cooling by radiation.” Another way to cool things is to bring colder air into an area; a front goes by, the wind turns northwest, colder air flows in, and the temperature drops. Cool air can also flow to the land from a body of water. This process is called advection , and it can bring in or take away moisture. The other cooling process is called adiabatic . This is simply a physical law that says when air expands, it gets cooler. What makes it expand? Lifting. When wind pushes air up a mountainside, it is lifting the air. It goes up the mountain to a higher altitude, where the atmospheric pressure is lower. The expanding air cools at a rate of 3 degrees C for each 1,000 feet it’s lifted (5.4 degrees F). If the air is lifted high enough, it may cool to the dewpoint, and then a cloud forms. It’s also important to note—that the opposite happens when air comes down a mountainside. The pressure increases, the air gets warmer, the dew-point and temperature separate, and clouds or fog dissipate. The entire process can often be

observed on a mountain. The windward side has a cloud near the mountaintop, beginning partway up the slope and hugging the mountainside and mountaintop with an eerie white cover. Then, on the downward side, we see the cloud shred off and disappear, leaving the downwind mountain slope clear; lifting, cooling, and condensing on the upwind side; descending, warming, and dissipating on the downwind side. We can sometimes see the same thing up high, when watching a lenticular cloud downwind and away from the mountain where a wave has formed. As the air flows up the front or windward side of the mountain, it continues upward well beyond mountain height, and is the front side of what we call a “mountain wave.” Like a mountain made of air, on this upwind side of the wave a cloud forms; then, as the air flows down the other side of the wave, the cloud disappears. It’s a fascinating cloud, because it doesn’t drift, it just sits in one place, forming and dissipating. It is a smooth, curved cloud that we’ve observed when playing with waves in a glider, often skimming close over the smooth, domed top of a brilliant white “lennie,” as we commonly call lenticular clouds. However, beware of flight under a lenticular cloud; that’s where the rotor is located, and the air is very, very rough—more on that later. One can watch the downwind edge of the cloud and see the motion as the pieces shred away and disappear. All this, the flow up or down a mountainside or wave, allows us to see the adiabatic process at work; lifting, reducing pressure, and cooling; lowering, increasing pressure, and heating; making a cloud and then destroying it. If the air being lifted up the mountain is unstable, the cloud does not dissipate; instead, it keeps going upward and may turn into the type of thunderstorm we would call orographic. That is the difference between stable and unstable air: stable air comes back down when the force lifting it is removed; unstable air, once it has been lifted to the point where clouds form, breaks loose from the lifting force and keeps going up by itself. Other things raise air and cool it. A cold front pushes warm air up, or air flows up over cold air, becoming, of course, a warm front. And the reverse of nighttime cooling is daytime heating, which makes air rise as thermals, the things glider pilots look for, to circle in and go up. When this air cools to its dewpoint, we get cumulus clouds, and if the air has a certain moisture content and is unstable, the clouds grow into thunderstorms. A meteorologist sees all these changes and additions, or subtractions, in a sophisticated way, studying upper-air soundings and weather information from many places and in many forms. A meteorologist is trained to study this mass of information and analyze it quickly. Nowadays computers are doing most of that task, but in some respects not as well. The computer lacks the local knowledge a meteorologist develops by being stationed at one location for a long time, knowing the little quirks of terrain, wind flow around it, and a host of other things the computer doesn’t know. Many old-time instructors and fixed-base operators

(FBOs) have developed a good weather understanding of their areas, and a talk with one of them about an airport’s weather, for future reference, can be rewarding. In a total meteorologist’s sense, we as individuals don’t have all the sophisticated weather information, but with today’s computerized world we can access quite a bit of it. However, even with this information, most of us will not know what to do with it as a total meteorological analysis. We do, however, have weather reports and digital imaging, which allows us to “see” what the weather is doing. We can relate what we see and call it the “big weather picture.” We can ask ourselves, simply: is it going to cool off and is there moisture present, either coming in now, or possibly coming in later, to go with the cooling? By doing this, it is possible to reduce all the complex weather factors to a simple understanding. What makes a front potent? Warm air being cooled. What makes clouds on a mountain? Warm air being cooled. What makes fog over a seaside airport? Wind bringing in moisture or cooling the air. What makes fog in the country? Moist air being cooled at night after the sun goes down. What makes low ceilings when it rains? Rain falling into lower air, raising the dewpoint, and causing low stratus and fog. We can go on and on, and finally relate any weather that restricts our visibility to temperature and moisture.

Season and Time of Day In our thinking of temperature and moisture, we should consider two important points: season and time of day. In the summer, things are more phlegmatic, and the weather is basically good, or it tries to be. In winter it is more violent and moves and changes quickly. But fall and spring are the most difficult times to predict. Air masses haven’t decided whether it’s winter or summer; temperatures can be colder or warmer than expected and give unexpected bad weather. The nights are not really long, but they are long enough to produce substantial cooling. A spring day can be mild and docile, or it can blow and be wild. All our weather thinking should be related to the time of day. We must simply ask, is it the full part of the day when it is warm, or are we catching up with the cool night, when temperature and dewpoint get together?

Terrain Terrain is an important ingredient in weather. Terrain that rises presents a chance for air to be lifted. Sometimes this rise in terrain—the orographic effect—can be very abrupt and dramatic. A mountain range may suddenly burst upward from flat ground, like the Rocky Mountains as one approaches Denver from the east, after flying over miles and miles of flat land in eastern Colorado. On the other hand, rising terrain can be subtle, like the gradual slope of the land from the Gulf of

Mexico’s Texas coast to the higher land in eastern Colorado. This rise sneaks up on us and doesn’t clearly display itself, but the silent flow of warm, moist air up this gentle slope can produce widespread fog or kick off thunderstorms. Terrain makes bad weather worse. A cold front being pushed up a mountainside is nastier than a front crossing Indiana, where the terrain is flat. Airmass thunderstorms are kicked off more quickly when wind flows up a mountainside. Fog can form sooner in valleys where cold air collects. But to make things more cheerful, mountains can help clear up weather on the downwind side, where downflow heats the air and dissipates clouds or keeps ceilings up. This effect often takes the clout out of cold fronts, making them more docile on the downwind side of a mountain range. Air can lose its moisture on the upwind side of mountains and be dry and clear on the other side. A vivid example of this appears in the far West, where the Pacific side of the mountain ranges gets a respectable annual rainfall and supports plentiful vegetation, while the eastern side of these same mountains is a desert, because most of the moisture is wrung out of the air on the western slopes. To a pilot over Los Angeles encountering unexpected bad weather, there’s a close escape by flying over the mountains to the desert, where the weather is generally good. All this, in its way, is the adiabatic process at work, with terrain helping it. When we think of terrain, we should not think only of mountains and valleys, but also of wide streams, lakes, and nearby oceans as well. Water and land generally have different temperatures. In winter, the land is colder than the sea— in summer, the reverse. We can see a demonstration of the temperature difference between land and sea when flying through the Intertropical Front along the east coast of South America. During the day the land gets hot, hotter than the sea, and great towering thunderstorms are everywhere—except over the sea, where it’s cooler. So, we fly out to sea in nice clear air. At night, however, the sea is warmer than the land, and more and more showers are found offshore, so now we fly over land for the best ride. In winter, the lee of the Great Lakes has snow and stratus, because the wind blows air across the lakes, where it picks up moisture. Then the air rises as it is blown up the slope of the Allegheny Mountains. The result is zero-zero, with snow and clouds on the mountains; the clouds are full of ice, and it takes 9,000 to 14,000 feet to get on top. Cities are a part of terrain-weather thinking. Cities make smoke and pollution, and those microscopic particles are something on which fog forms. Smoke and air pollution make the formation of fog easier, and a wind carrying pollution toward an airport is a setup for poor visibility. That’s terrain, human made, but still terrain.

Wind

Another important factor in weather is wind, which plays a major role in a pilot’s life. It affects us from the moment we take the airplane out of the hangar until we secure it for the night. Wind tells us how we must handle an airplane on the ground and during takeoff; it tells us how we must think and act while flying close to uneven terrain; it tells us how short we can take off and land and what up and downdrafts we can expect. Wind affects the performance of our airplane. A big jet weighing 290,000 pounds can take off from a certain runway in calm conditions; a 10-knot headwind can increase the gross to 300,000 pounds, but with a 5-knot tailwind, the gross is reduced to 280,000 pounds. The same rules apply for a Cessna 172 too; only the numbers are different. Wind is also important when thinking about large-scale weather. First, on a weather map we notice, almost automatically, that if the isobars are jammed together like tracks in a railroad yard, it tells us the wind will be strong, or if they are wide apart, the wind will be lazy. Then we look at direction. East winds may bring bad weather, west winds sunshine. Wind from a sea such as the Gulf of Mexico brings moisture that can create bad weather. Knowing what the wind is, or catching its changes in velocity or direction, can give us good weather clues. Wind is layered and blows differently aloft than it does on the ground. The wind up high tells a pilot about speed for a trip, and therefore, the required fuel and reserves. Wind just above the ground, within the first 1,000 feet, tells about shear and its hazards during takeoff and landing. While the wind may be calm on the ground, especially true in valleys and at night, it can be blasting along at high speed only a few hundred feet above the ground, which can be devastating to a climb rate as you suddenly fly into an unexpected tailwind. Part of preflight weather gathering should be a close inspection of the gradient wind; the wind above the surface out of the earth’s friction layer. (Another term for this is PBL, which means planetary boundary layer; a fancy name for what we’ve always called the friction layer.)

The tremendous force of wind drove this board (measuring 10 feet × 3 inches × 1 inch) through a palm tree in Puerto Rico during a hurricane. (NOAA PHOTO) An important part of wind action is convergence or, more simply, places where winds from opposite directions bang into each other and pile up. The idea of convergence and what happens because of it is difficult to pinpoint, and the actions it causes are complicated. A convergence area can be very big, like the Intertropical Front, also know as the Intertropical Convergence Zone (ITCZ), where northeast trade winds run into southeast trades and create an area of large cumulus and thunderstorms. Convergence can also be tiny, where a sea breeze meets inland air and forms a miniature front of no special consequence, except for a line of clouds a little way in from a coastline. These are called sea breeze fronts and generally are mild, but just to keep alive the realization that weather’s ability

can surprise us, thunderstorms occasionally will develop along such fronts. Fronts are a demonstration of convergence, and so are low-pressure areas. The important point is that almost any time convergence is present, there will be some sort of weather associated with it, because of the process of air being lifted and cooled. Divergence is the opposite of convergence. Air flows down and away, which again, in going back to the adiabatic process, heats up and generally gives good weather. A high-pressure area is a large-scale divergence, a mass of sinking air. This sinking air in a high, and the rising air in a low, affect flight more than we realize. When I (RNB) began flying the first 747s in 1970, a flight plan filed from New York’s JFK to Europe made it important to note whether we would be climbing through a high or low pressure area. That would determine what altitude to file with Air Traffic Control (ATC) for crossing Nantucket, a checkpoint about 176 miles from JFK. If climbing in a low, the airplane could reach 33,000 feet, because the converging, rising air would help the climb. However, climbing through a high, with its diverging and settling air, the climb would be slower, with 29,000 feet at Nantucket. About all those early, low-powered versions of the airplane could comfortably handle.

The biggest convergence zone: the Intertropical Front, shown in this satellite picture. Thunderstorms show on South America’s northwest coast westward into the Pacific. It’s less active eastward until the central South Atlantic toward Africa. This is temporary as it strengthens and weakens because of activity or time of day.

If you fly between the Northern and Southern Hemispheres, you will have to cross this area and its big thunderstorms—tops into the 60,000-foot range—and heavy rains. (NOAA IMAGE) Of course this effect works on any airplane. No doubt many pilots—especially those flying small, lower-powered aircraft cross-country in a fresh high-pressure area—have noticed how the airplane seemed to fly somewhat slower and worked harder to keep normal cruising speed. This is even worse in mountainous regions, but that’s for another reason—waves—which we’ll talk about later in the chapter on turbulence. A good pilot is wind conscious, aware of its direction and velocity, knowing how it smells and feels, sensitive to a warm, humid wind or a crisp, cold one, where it came from, and what kind of weather it will bring. A good pilot awakes in the morning, looks out the window, sees where the surface wind is coming from, looks up at the clouds, checks which way they are drifting, and learns the wind aloft. All through the day, that pilot is subconsciously aware of the wind, and if it changes, they sense it, then contemplates what this may mean. Any weatherwise pilot puts the wind and flying together, visualizing it tumbling over trees or buildings near the approach end of a runway and what that will do to the airplane. Our pilot tries to “see” the downdraft on a sharp mountainside and relates wind to aircraft performance, as well as to the weather. The good pilot is animal-like in sensitivity to the wind, feeling and understanding its motions by instinct.

Clouds A pilot literally looks at the weather to see what it’s up to. One of the main things observed is clouds. They tell a big story. There are two cloud types, cumulus and stratus, and all cloud designations are some combination of them. There are three classifications: cirrus, nimbus, and alto. Cirrus are high-altitude clouds, and because they occur in high, cold air, they are made of ice crystals; but they still follow the cumulus and stratus designations. Nimbus is simply a name given to clouds when precipitation starts to come from them—like cumulonimbus and nimbostratus. Alto simply designates height; it means a cloud is at medium height, somewhere between 7,000 and 25,000 feet, and again it is used with the basic cloud forms, as altostratus, altocumulus. You never hear “altocirrus,” because cirrus by itself is high. The important part about the two basic cloud types is their action and this, in turn, tells how they were made. Cumulus clouds are bouncy clouds. They were born of instability, born in air that once it starts up, wants to keep on going—for that’s all instability is. Stratus clouds are smooth and flat, or almost flat; their air is basically stable. Heavy precipitation comes from unstable clouds; steady, light rain or drizzle,

comes from stable clouds. Said another way, ceilings and visibilities will be high enough to land during unstable conditions, except we may briefly have heavy rain or snow showers, causing the visibility to be near zero, the runway slick from rain or even flooded, with stopping difficult. Precipitation from stable clouds means low ceilings. Light precipitation can bring zero ceiling, or near it, with the condition widespread and of long duration. So fluffy white clouds are cumulus, and flat, layered ones are stratus. To make it more confusing, they can be in combinations, as stratocumulus, for instance, which is a layer of clouds containing some instability. The precipitation from the clouds of slight instability can be light. The stories clouds tell are varied. Cumulus clouds are generally thought of as pretty, fluffy white things floating in a blue sky. They mean good weather. But they are not all the same. We know that any cumulus-decorated sky will have choppy air underneath the clouds and smooth air on top. If we look at the clouds more closely, we can get an idea of how choppy it will be underneath. If the clouds have a shredded look, like cotton that’s been pulled apart, it’s probably rough; you are slapped around the sky, and it’s a good bet that the surface winds are strong and gusty. When we fly gliders in these conditions, the rising thermals are generally chopped up and difficult to stay in. If, however, cumulus clouds are bulbous and fat, the choppy air will not be so choppy, and the up and downdrafts will be better defined. You rise and descend more like a boat in swells at sea. We also look at these fat cumulus clouds with more suspicion, because they are the kind that may grow large and turn into thunderstorms. We can tell without even looking at a weather map, merely from the type of cumulus present, a lot about the synoptic situation. The first type, the shredded kind, are in an air mass that’s close behind a low, and a front has gone by with fresh, vigorous air flowing into the area. We’re in for a few days of good weather. The fat cumulus clouds say that we are deeper into a high, perhaps on the back side of it, and warmer unstable air is coming in. Somewhere to the west a cold front is probably starting our way. Stratus clouds tell a different yarn. We may be flying in a mountainous area, such as the New England states. There is a high overcast made of altostratus; the visibility is good. Our destination, in the mountains farther south, is reporting 8,000 feet and 5 miles visibility with light rain—good enough. We know there’s a rain area, a warm front approaching, but the forecasts do not make our destination really bad until long after our arrival. We fly on and notice rain on our windshield. The visibility drops some, but there’s enough. We are happy, even though it rains a little harder. But then, looking down in a valley, we see a wisp of stratus below, just a little thin glob of cloud floating along by itself. That should be a red flare signal! Things are happening; enough rain has fallen into the lower air to raise its dewpoint, and stratus is forming; stratus is the cloud low ceilings

are made of. It’s forming faster than the forecasts indicate; the next thing we know our destination will have about a 300-foot ceiling or less. We review our fuel, check the alternate and destination weather, which is going down, and wish we could hurry and get there before it socks in. All this was told to us by a little piece of stratus.

Three layers of clouds and the stories they tell. Looking south, from 32,000 feet, we are flying west. We’ve passed through the jet stream, under which is a cold front—we’re on the back side, the front moving east. Up high is cirrus cloud, the thick band from the jet stream: it was flowing from 221° at 155 knots. Below the jet stream is an altostratus deck, around 20,000 foot. Down low and left is the front’s back and cumulonimbus clouds. To right and behind the front are typical post frontal cumulus and stratocumulus cloud, with average tops about 12,000 feet. It’s November, so maybe there’s ice in the cumulus. Position: mid-ocean, North Atlantic—50° north and 40° west at 1649Z, November 10, 2005. (PHOTO BY ROBERT O. BUCK) We are flying westward on a summer day, on top in clear air with excellent visibility; below, it’s hazy and difficult to see. Way west of us there’s a cold front, which is forecast to arrive at our destination long after we do. But suddenly our eye catches a different shading in the high sky far ahead. We take off our sunglasses to see it better, but we can’t; we put them on and squint a little, trying to pick it out. We fly on and look some more. Then we’re certain. The western sky

holds solid cirrus, white and innocent looking, but it’s a sign that says let’s check that front; it may be moving faster than we thought, or a pre-frontal line squall may be developing. These are a few examples of the many things clouds tell us; they are an entire weather story placed in the sky for us to read. We can study for a long time and never know the whole story, but it is profitable and interesting to try.

1 . Because weather reports (METAR) now use Celsius (C), we’ll do the same, with an occasional reference to Fahrenheit (F) just for old times’ sake.

3 Some Thoughts on Checking Weather Weather is fickle enough to justify checking it prior to any flight. Even when shooting touch and goes at the local airport on a lovely Visual Flight Rules (VFR) day, information on wind changes, some precipitation beginning, or other weather issues can be valuable. Having weather and forecast knowledge cuts down on alarming surprises or can reward us with some great flying that might otherwise be missed, because we didn’t understand weather well enough to see through the questionable sky. Being inquisitive about weather must be part of our flying character, because it creates an awareness that is necessary even when one’s log book shows thousands of hours. It comes down to the fact that the moment a person says, “I’m going to learn to fly,” that person needs to add, “and I’ll learn weather, too.” Flying and weather should be thought of as one skill, one art, never separated. Anytime we fly, weather is part of the game, and the pilot, regardless of mission, should know what the weather is, what it’s supposed to do, and have safe alternatives if it turns sour. We must always be aware, on every flight, that safety is our goal and weather the adversary.

It Isn’t Easy Now where and how do we get this weather information? It isn’t always easy, and there are times we may takeoff feeling the necessary weather questions are not clearly defined. Despite all the available information, today’s systems still leave the weather decisions and their burden firmly on the pilot, a fact that isn’t always recognized. Weather information comes from a plethora of services. The most important— and official—weather information still comes from telephoning the Flight Service Station (FSS ), [also referred to as Automated Flight Service Station (AFSS ), but we’ll use FSS throughout the book], which is overseen by the Federal Aviation Administration (FAA). For those who desire computerized self-briefing, one of the two FAA-approved weather websites—Direct User Access Terminal Systems (DUATS ) or Direct User Access Terminal (DUAT )—also makes sure we have this same accurate foundation of basic weather information. We can also file our flight plans through their services. Away from the FSS or DUATS/DUAT, there are other weather briefing and flight planning sources, many of which source through personal electronic device

applications. A lot of them are excellent, with some providing their information in-flight, through data-linking of everything from maps and approach charts to navigation and weather data. Another source comes from high-end commercial facilitators that offer weather and flight planning services, as well as fuel, lodging, food, and more. Probably everyone, at various times, watches TV weather for a look and study of weather’s general setup—the synopsis—but it is important to realize this is something from which we gain a general plan of the weather picture, and should not use it as detailed weather information for flight. Self-briefings have opened a whole new dimension in flight planning. The quantity of information is extensive, but with its nature of presentation by computer, requires the user to evaluate the information as a lone entity, one who, for most of us, is not a trained weather professional. We need to fathom that weather data is not just information; instead, it requires understanding of not only what it says, but also what it means and what to do with it. We must weave this task precisely and accurately, not on assumption. Only then is it useful to safe flight planning. Weather information should never sway us to accept it passively; a knowledgeable, constant evaluation–decision process is necessary. Weather is one of those things about which we learn basics, but the knowledge is best honed with face-to-face mentorship and subsequent verification by flying experience, done within the limits of our weather knowledge. This is especially important when we are new and unfamiliar with the subject. However, an irony exists in that the task of deciphering weather information has been placed in the lap of pilots with greater magnitude than ever before, but at the same time with arguably less mentor-ship, than aviation has ever experienced. The explanation of this issue is a story we feel worth telling. Back in the late 1920s, the United States Weather Bureau (USWB ), now the National Weather Service (NWS ), was given the task of supplying weather information to the budding aviation industry. By the 1950s, a partnership evolved between the Weather Bureau and FAA by bringing aviation weather and pilot briefings to the new FSS system. Often, the facilities were co-located in the same building; if not, you could brief at either one and call the other. The FSS briefers/specialists* were well trained on providing the now standard weather briefing format, using approved weather information from sources like their neighbors at the NWS and other government weather-related agencies. Conversely, NWS meteorologists were trained to use their meteorological expertise in aviation-related weather briefings. FSS briefers also handled other functions, such as air–ground weather information, airport advisory for uncontrolled airports, flight planning, and helping distressed aircraft. Most FSS briefers were not meteorologists, but they developed a lot of helpful local weather knowledge. Supposedly, they were not to use this, but they did off-the-cuff, and it was usually very helpful. Next door at the Weather Bureau, a pilot could get a meteorologist’s sage knowledge of the weather; they dug into some real nitty-

gritty, explained it to you, and when you were ready to fly, your grasp of sky was pretty good. Not only could we telephone these facilities, but we could also walk in and have excellent face-to-face weather briefings at the FSS and/or NWS facilities. As said in this book’s 1996 edition: “There is nothing better than a human to talk to, ask questions of, and get the picture we need of what’s out there and how it is going to behave.” The real jewel of this whole deal was that we learned a heck of a lot from those personal visits, not only about weather and flight, but also about prescribing sensible limits to weather flying. What happened? The FSS system became the primary source for all pilot briefings, and eventually it was decreed that the NWSs would no longer give pilot weather briefings. During the peak years of the local FSS system, in the early 1970s, there where nearly 400 airport-located facilities nationwide, making it very likely most flying trips had some opportunity for face to face weather briefings, and all they offered in thorough weather analysis, as well as assistance to the less savvy weather pilot. Then, by the later 1990s, with computerized weather data coming up to speed, political powers and budgeting began consolidating the local FSSs, and today, in the lower 48 United States, there are three main centralized facilities, plus as of this writing, three other augmenting facilities which assist the work load of the “big three” centralized FSSs. An exception is in Alaska, where a system of multiple, local FSS stations remains, which is a smart move for that areas demanding weather flying environment. Also, many of the 120 or so NWS offices began relocating away from airports, and today not all are accessible 24/7, whether by telephone or walk-in. So has ended the era of walk-in briefings at FSSs and many NWS offices. The big loss, in our view, was the mentoring that went with it; especially helpful to the new or not too weather-savvy pilot, let alone experienced ones who were old-school smart and respected a good briefer or meteorologist’s input. And this is why we believe the modern pilot needs to understand weather, and its application to aviation, more than ever before. So what is left? Fortunately, the centralized FSSs gives us reliable, consistent weather briefings and in-flight weather data, along with flight plans, assisting distressed aircraft, and so on, through telephone or radio contact with a real human being, the FAA briefer/specialist, and the next best thing to face-to-face contact. Actually, there was originally a bit of a challenge with FSS centralization, as the FSS briefer we’d talk with was the first available one who answered the nationwide phone system; such as chatting with someone on the East Coast, and the familiarity with briefing that area while we were flying in, say, California. The FSS briefers were stuck with that as much as pilots were, but at the same time they’re professional attitude worked hard to fulfill our needs. Today’s FSS system has improved, doing a good job in matching FSS briefers familiar with areas we are flying; that’s why the current phone system asks what state we are flying from. Actually, many FSS briefers/ specialists are general aviation pilots, enhancing their understanding of the important pilot-weather interface. With FSS

communication being human, it is not as fast as our own view on a computer or personal electronic device, so may take a bit longer. However, this trade-off gives us the latitude of human contact, and the briefer’s trained expertise, versus a computer’s pragmatic inability to question and discuss. So with a little patience, phone contact uses the system as it has successfully worked for decades. Maybe our impatience is a by-product of the times. Never the less, whether we get our weather from the FSS or a computer, the task is still the same; the pilot must ultimately understand, apply and make decisions from the data, allowing a safe flight. And the NWS meteorologist? The NWSs can be reached, depending on how proactive we find each office. If we do reach an NWS meteorologist—either by phone or walk-in—while they do not give aviation briefings, they are free to give an opinion of the weather. Usually, they are quite helpful and concerned about our needs. It is worth making an effort to call (their contact numbers are accessed through the NWS website), as well as visit an NWS office, as it is a great learning experience. On the other hand, if we decide not to call the FSS or NWS and are using the very popular computerized weather, we need to have that well-studied understanding of all this weather business, especially what we should have as a minimum for an appropriate weather briefing. With that thought, how many pilots, either new or well experienced, can always say they are on par with well trained weather personnel who immerse themselves in it everyday, solely for our benefit? In a final thought, there are quite a few pilots who feel computer weather is plenty adequate, and that the system could alleviate the FSS human briefing all together, being instead totally dependant on computer-only weather data and flight planning. Of those who feel this way, how many forget they came into aviation in an era where we had face-to-face FSS and NWS briefings, or learned from spoonfed airline or military environments–with superbly equipped and performing aircraft that can handle weather far better than most general aviation operations? By going solely with computer weather, where do aviation’s new pilots find mentorship as was afforded for many of us in years past? And we consider the inability to get computer access, for whatever reasons, were a quick phone call can save the day. If the aviation industry goes this way, it risks creating a whole generation unaware of how delicate and important is the weather-aviation relationship, and how to orchestrate it. A century of honed understanding, shot. Then, how many accidents, rules, and restrictions later before we have to reinvent the wheel of aviation and weather; if there is still someone around who understands it?

It’s Approved and Official A very important point is the difference between getting any sort of weather

information versus approved weather information. The official government term for this is “Primary Weather Product.” These forecasts, actual weather reports, adverse weather statements and warnings, wind products, synoptic analyses, and airman notices are approved by the FAA in conjunction with the NWS and other governmental weather facilities. They are deemed worthy of the regulatory and safety needs, necessary and suitable, for aviation weather decisions and flight planning. When we get a weather briefing from the FSS, or DUATS/DUAT, as well as flight-planning services that reference these same methods and are approved accordingly, it is not only of Primary Weather Products but also packaged into a briefing format called a “Standard Briefing.” This guarantees we get full coverage of adequate data needed for safely planning a flight. The briefing also puts us on record as receiving this data, which basically covers us if there is an incident where, no doubt, the FAA will want to know if we received a full weather briefing. So when we stray from an FSS or DUATS/DUAT briefing format, we are best to know what we’re looking for and also realize we are not on record as receiving an adequate pilot weather briefing. The Standard Briefing looks at its data for complete coverage over the whole route of the flight. Below is a short list of the weather-related criteria of the Standard Briefing: • • • • • • •

Adverse conditions Synopsis Current conditions En route forecast Destination forecast Winds and temperatures aloft Notices to airmen (NOTAMS)

We can find a guide to weather products considered primary, fulfilling most of the above criteria, through the NWS Aviation Weather Center (AWC) website. But wait—that’s not all! If we have already briefed a flight, yet want a final check of things before takeoff, we call the FSS and ask for an “Abbreviated Briefing” that updates things without another long Standard Briefing. On the other hand, if we are more than six hours before a planned flight and want a look at the weather toward what to expect or whether we’ll go at all, the FSS offers an “Outlook Briefing.” Then there is also weather information the FAA calls Supplementary Weather Products. These are weather offerings that by definition offer enhanced situational awareness of the whole weather picture. This is very important to understand, as many of these products are the most user friendly and enticing of all weather products; primary or supplementary. They offer excellent graphical displays, giving layered and sometimes profile views of icing, turbulence, thunderstorm

activity, temperatures, winds and cloud cover. They can tempt us to accept them as primary data, but they are experimental and remain as supplements to Primary data. For a concise explanation of Primary and Supplementary products, the FAA’s book Aviation Weather Services AC 00-45G (version G as of this writing) outlines the whole system. Lastly, once airborne, we continue sourcing Primary Weather Products through the FSS system. Using radio, we either contact the FSS directly or use the excellent En Route Flight Advisory Service (EFAS ), also known as Flight Watch . If we’re fortunate to have electronic flight instruments allowing data-link weather, we can have the data on a snazzy display, right in front of us. So we can see that years back, we lowly pilots didn’t worry about official or legal weather information. It came in standard form from these FSS and NWS professionals. They had what was needed, and walked us through those nuptial years of our relationship between aviation and weather. Now, a lot more is up to us.

How It Works So a scenario might be something like this: We’re going from Burlington, Vermont, to Morristown, New Jersey. We can call the FSS folks by phone, requesting a full “Standard Briefing.” There is also that choice of self-briefing through DUATS/DUAT, whether from a computer or through their application on personal electronic devices. Another slant is to access one of the popular flightplanning applications, also self-briefing. In this example, however, we usually go through the self-briefing, study it, then print it out, and finally call the FSS for a “Standard Briefing.” This way we have heads-up to all the data, which helps us process and picture the FSS briefers’ spoken weather data; this comes up again in subsequent chapters. Again, with the FSS briefer, we have that chance to ask questions and know we’ve covered the minimum data necessary. We’ve also checked some of those Supplemental Weather Products, in this case allowing us a “forecast” picture of possible icing, turbulence, and thunderstorm potential. Also, our destination of Morristown does not issue a Terminal Aerodrome Forecast (TAF), only an Aviation Routine Weather Report (METAR). So we cover this lack of a Morristown TAF by looking closely at the Area Forecast (FA) covering New Jersey, which gives us an idea of conditions during our arrival. We also call up two nearby New Jersey airports that have published forecasts, Newark and Teterboro. However, these two TAFs are only reference, as the area of TAF validity only covers a five statute mile radius from an airport’s center. This process verifies both weather and other flying information, including the NOTAMs, SIGMETs, AIRMETS, and PIREPs. 1 To really verify the weather, especially if it is a real challenging day that leaves us feeling a bit uncertain after the briefing, we can call or, if possible, visit the local NWS office and chat with a

meteorologist. This is where we ask their idea of the weather in the Morristown area, what the weather will be like from Vermont down through the Hudson River Valley into New York and New Jersey, and how confident they are about the prognostications. That gives a better feel for the weather and completes an excellent briefing. What we do with all this information remains the same as it has always been. The key to keep in mind is that a preflight briefing is just what it says: before the flight. Once the wheels leave the ground, the ball game changes. Then it becomes the serious task of keeping up with the weather, watching to see if it’s doing what the forecast said or not. “Not” is the important word and emphasizes the need for being prepared to handle the situation a “busted” forecast will confront us with; go to alternate, turn around, climb, descend, whatever. Weather can change very quickly, and in no way does the currency of information before takeoff relieve us of the responsibility of keeping an eye on what’s going on, watching for weather’s periodic fickle actions. A very important point about all this slick weather information is that it is still weather with all its faults. The clipped, official look that electronic access and airborne data link gives us doesn’t relieve the pilot one iota from watching how it goes, being cautiously cynical about forecasts, and having alternate action well thought out and provided for—this is very important. Another important part of any weather briefing is the “IF” information: if it doesn’t do this, it may do that. This is the kind of information we always got when talking face-to-face with a meteorologist, leaning over a weather map, absorbing the picture of lows, highs, fronts, and the rest. To show how this “IF” information works, read this forecast issued: SYNOPSIS VALID UNTIL 270400 AT 10Z LOW PRES CNTRD OVER THE CAROLINA CSTL WTRS. WILL MOVE NWD DURING PD. 00Z LOW CNTR LCTD IN NEW ENG CSTL WTRS. RMNDR PD LOW WILL MOVE NEWD. [At 10Z low pressure centered over the Carolina coastal waters will move northward during the period. By 00Z low center is located in New England Coastal waters. Remainder of the period the low will move northeastward.] In addition to the synoptic, note the area forecast for New Jersey: NJ CIGS BLO 10 OVC VSBYS BLO 3SW. CLD TOPS ARND 160. ARND 17Z BCMG 15-25 OVC VSBYS 3-5SW. OTLK … MVFR CIG. [New Jersey: Ceilings below 1,000 feet overcast with visibilities below 3 miles in snow showers. Cloud tops around 16,000 feet. Around 17Z becoming

1,500–2,500 overcast with visibilities 3 to 5 miles in snow showers. Outlook is for Marginal VFR due to ceilings.] So our grasp of this situation is that a flight into the New Jersey–New York metropolitan area will have low clouds, but, as we learned from the New Jersey forecast, quite flyable after 17Z, because the real nasty stuff will be tracking off to the northeast. Of course that might affect our flight en route, so we’ll be checking that carefully. Gradual improvement is what it’s saying, because the low will move off to the northeast. However, lows tracking along the coast often have a sneaky way of sliding north, up the Hudson River Valley, slowing down, even stalling, and leaving the weather poor and marginal much longer than forecast. Also, with snow showers in the data, if in the clouds on an IFR (Instrument Flight Rules) flight, the possibility of ice comes to mind. If available, we should also check satellite weather, giving us an idea of cloud cover, and NEXRAD (radar), for convective clouds, even if low-level winter stuff that are not thunderstorms; the radar is, after all, showing precipitation. However, the satellite picture is not for interrupting cloud bases, so we also take a look at the Weather Depiction Chart, as well as Supplemental Weather Product of graphical forecasts for ceilings, icing, convection and turbulence. Ultimately, we need to remember that fronts, lows, highs, and other weather can move differently than forecast, and pilots need be alert to this fact. But what do we do about it?

You Are the Meteorologist Chances were, in the good old days, if we talked to a meteorologist, they would tell you how confident they were about the movement of that low pressure or some other forecast situation. So getting ready for takeoff, we not only knew what the weather was likely to be, but also that a suspicious eye should be kept on the development, making sure that low pressure, or whatever phenomenon, didn’t change its mind. In our present age, however, the weather information we may have written down or seen on an electronic display has no “IF” information, so we have to assume the role. Be that meteorologist. Today, the pilot should be weather-wise enough to know when to be wary of a setup and that it is necessary to keep an eye on it. In the TAF format, there’s a hint of the forecaster’s confidence when you see a statement such as: “PROB30 0120/0122.” Decoded, this says there is a 30 percent chance between 2000Z and 2200Z on the first of the month of something possibly changing—for example, snow showers, visibility lowering, and so on. A percentage like that in the forecast should make us a little more wary, because it admits that a variable exists that the meteorologists are not dead certain about. On the other hand, if there is a better than a 50 percent chance of that something occurring, the statement in a TAF may

say “TEMPO 2812/2816,” meaning the phenomenon may be temporary. That temporary weather is part of the whole weather forecast that encompasses either side of the temporary time frame; the worse weather is that which governs our decisions. A little more complex, we offer an example that is part of a forecast: 2812/2912 03005KT P6SM OVC012 TEMPO 2812/2816 4SM -DZ BR OVC008 [The forecast is valid between the 28th of a month at 1200Z until the 29th at 1200Z. In that time, the wind will be from 030° at 5 knots, with visibility greater than 6 statute miles, with an overcast at 1,200 feet. However, between the 28th at 1200Z until 1600Z, the weather has better than a 50% chance of dropping to a visibility of 4 statute miles in light drizzle and mist, with an overcast at 800 feet.] The deal here is that we have to flight plan for the lower temporary weather; which just happens to bring Marginal Visual Flight Rules (MVFR ) conditions to IFR , because the clouds are a ceiling, and it is below 1,000 feet. As we see, these conditions of probability and temporary are just two examples of science’s complex but fascinating mechanisms. To be good, safe pilots, we should address these challenges with that study of weather— meteorology. Also, we again emphasize this basic importance as being so relevant today, with weather information and briefings coming from automated, impersonal presentations. There are many excellent books and other sources that go into the science and make it painless and interesting. We have quite a few listed in the Suggested Reading section. Historically, however, the study of weather has been hard to sell, even to very active pilots, and possibly this issue would make a fine thesis from psychological study. Maybe it’s the science, possibly weather’s pragmatic nature, or maybe it’s complexity comes to some as something far too abstract; or annoying. Who knows? But the study of weather isn’t all that bad and can actually be enjoyable if properly mentored and taken in stride. The payback for weather knowledge is making aviation work better for us through safer, more comfortable, and enjoyable flying, which is also far less intimidating to accompanying friends and family. We remember that this flying business is not a 100 percent completion operation … we’ll spend some nights in unique motels. Those nights will quickly pass in trade for the many flights we do complete that offer us utility and pleasure from being flown knowledgeably and without angst. Obviously, few of us will be meteorologists enough to know all the situations. A good meteorologist pursues extensive and on-going study of the science, then develops the innate skill of an intuitive investigator. However, we can protect ourselves in two ways: one, never be smug about a forecast, and two, while flying, keep up with the weather by periodically getting current airport weather and then comparing it with what the forecast promised. If there is a difference,

such as lower ceilings and/or visibilities, or the weather is not improving as forecast—anything not as originally forecast—then it’s time to check more recent METARS, get new forecasts, and find out about any new or updated SIGMETs, AIRMETs, PIREPs, and Convective SIGMETs; as well as investigate through satellite and NEXRAD, if we have that equipment onboard our aircraft. When things begin to look poorly and are not working out as expected, it is also a time to review and recompute our fuel supply, at the same time thinking which way we’ll run to stay out of trouble. With weather information a mass of codes and formats, it’s important to remember that they periodically change. Though sometimes subtle, there are also times when big changes occur, as in 1996, when METAR and TAF were introduced and our Fahrenheit world became Celsius. At the time, few liked the change, but it happened, it’s now everyday stuff and life goes on. This is a reminder that with aviation information often critical, we have to go with it and keep on top of things. The constant changes to weather information not only helps pilots directly, it enhances forecasting. One example was the introduction of Automated Surface Observation System (ASOS ) and Automated Weather Observing System (AWOS ). The great part is there are now hundreds of airports reporting weather; a majority of smaller airports considerable distance from larger airports that are reporting METARs and Automatic Terminal Information Service (ATIS ). Checking these many ASOS/AWOS airports by electronic access, listening on radio while flying by, or calling ahead on their individual telephone numbers, (available in the Aeronautical Information Manual (AIM ), the Airport/Facility Directory (A/FD ), as well as off the FAA’s website www.faa.gov ) , can reveal weather issues even before we depart. This data is filtered through the aviation weather system, allowing us to have it in aircraft via data link to Electronic Flight Instrument Systems (EFIS). It is also used by the NWS and affiliates to improve forecasting accuracy, which along with other information leads to the previously mentioned data for icing, thunderstorms, turbulence, and so forth. With all of the data put together in flight-planning presentations, not to mention the model concept of weather forecasting and easily available atmospheric information … well, it goes on and is a book in itself. We think it makes investigating weather fascinating, as well as enhances our use of aviation. However, even with all this, it will still be the pilot’s responsibility to get the weather, interpret it, decide what to do about it, and be suspicious of its fickleness. Of course, a pilot must always be aware that technology can hiccup and miss the weather, tell it wrong, or forget to put it out at all. There are various ways to keep up with weather as we fly, and more on that later, but there are a few methods worth mentioning now—even if we repeat them later on:

1. Through our aircraft radios, we should ask and listen for weather updates on Flight Watch (EFAS)—122.0 MHz. If Flight Watch is unavailable, we can get the information by contacting the FSS. Also, please give PIREPS—they are the only source of real conditions shared for other pilots and can be extremely important as go–no go information or as an alert for imminent weather safety issues. It is especially helpful if we are the first flight of the day. 2. As you fly, listen to ASOS, AWOS, and ATIS for the current weather at airports along your route, noting if they are different from forecast. If so, it’s wake-up time to learn what’s happening. ASOS/AWOS are usually minuteby-minute weather data, whereas ATIS is from observations up to an hour old. There are, currently, nine different versions of the popular AWOS, but most have the key weather data of altimeter setting (pressure), wind, temperature, dewpoint, and density altitude. Better systems emulate ASOS, adding visibility, cloud ceiling, and precipitation identification. High-end AWOS gets into lightning and thunderstorm data. However, because these systems take observations as though looking vertically through a narrow funnel, they can’t tell us what the surrounding weather is (fog bank north, clouds on hills, etc.), nor do they warn of approaching thunderstorms, except when they are directly overhead, and then only in those versions doing so. Some AWOS systems, however, have the ability to inject human observation, which brings us back to the quality of original human-observed weather reports. ASOS and AWOS weather observations are considered good for a 7-mile radius, so in between we rely on area forecasts, PIREPs, radar, and so on. Sometimes the systems can seem inconsistent, with visibility possibly confused by haze, ice crystals, and snow. Fluctuating temperatures can be caused by clouds drifting over. Winds, clouds, visibility, and precipitation seem out of whack due to a passing shower or thunderstorm or even a good thermal or dust devil. However, these anomalies are small compared to the excellent benefit of ASOS and AWOS, and they are improving all the time. 3. Hazardous In-Flight Weather Advisory Service (HIWAS ), available on selected VOR frequencies, gives us a heads-up to contact FSSs or Flight Watch for details. 4. The most important way of gathering the latest information is to look through the windshield at the signs of weather: clouds, sky, precipitation, ice, thunderstorms, wind on the surface, and anything else in the atmosphere. There will be constant improvements allowing better information, userfriendly displays and communication sources. But forecasting will never be 100 percent accurate, so the final weather responsibility will always be ours! In short, as my son said: “the sky is weather and the sky is where we fly … learn it.”

You Are the Captain!

As we’ve tried to make very clear, it is the pilot’s responsibility to get the weather, analyze it, and then take action. It’s more difficult for lower-time pilots to make a decision after looking at the weather briefing material, but regardless, the final decision to go or not must be theirs. FSS specialists have made mention that pilots frequently ask “Should I go or not?” This raises the hackles on experienced pilots who have spent a lifetime protecting the command authority of pilots; take that away and you might as well give up f1ying. It’s the sacred part, because the pilot finally is responsible—attend an accident hearing and see how true this is as the blame is placed on the pilot, as it is about 80 percent of the time. Aside from that, no one knows how a pilot feels, not just the physical feeling for that day, but how the pilot feels about his or her experience level, ability, aircraft, and equipment. If pilots don’t maintain a sense of control over their operations there will be a degeneration of command, and it’s not impossible to visualize a ground-based government “dispatcher” telling us if, how, and when to fly. Worse may be considerable restrictions to our flying, training, and so on. The powers that be measure concerns from incidents, (accidents) and public concern—often the nonflying public. At this writing, this issue needs serious improvement. It is appalling to think of a pilot asking a briefer whether or not to fly. If a pilot cannot make that decision and has to ask someone else to make it, then the decision has already been made, because if there is that much doubt and uncertainty, then the pilot should stay on the ground. The uncertainty is the decision!

*

terms briefer and specialist both used for the same FSS person who provides briefings and information to pilots.

1 . NOTAM: Notice to Airmen. These reports include things like a VHF omnidirectional range (VOR) being out, runway out of service, etc. Obtained during briefing and when requested. SIGMET: Significant Meteorological Information. Issued when significant weather may affect the safety of all aircraft. These reports include severe and extreme turbulence, severe icing, and visibility less than 3 miles in sandstorms, dust, or volcanic ash. Convective SIGMET: Convective Significant Meteorological Information. Issued for thunderstorms (TRW) and imply severe or greater turbulence, severe icing, and low-level wind shear. Some of the criteria include a line of thunderstorms at least 60 miles in length, with TRWs over at least 40 percent of its length. Also, an area of 3,000 sq. miles or more with 40 percent storm coverage, as well as tornadoes, line squalls, embedded thunderstorms with wind gusts of 50 knots or more and hail of ¾ inch or more. This stuff is bad in

any form, so just because it might not be up to the SIGMET criteria, does not mean it’s smart to fly in it. AIRMET: Airmen’s Meteorological Information. These are notable weather phenomena of less intensity than SIGMETs. Also including areas of at least 3,000 sq. miles having cover moderate icing, turbulence, winds over 30 knots, ceilings under 1,000 feet, visibility less than 3 miles, mountain obscuration, and other nasty things. AIRMETs apply more to small aircraft without abundant equipment and performance, but are still worth listening to for the big boys. An AIRMET may be part of an FSS briefing. These all are issued as needed, and you pick them up by warnings on certain VOR stations, Flight Watch, ATC, FSS, as well as NWS computerized products. PIREPs: Pilot Weather Reports. It is just what it says. Call the FSS on radio or telephone, either directly or through the EFAS—radio call “Flight Watch”— and give your flight conditions. PIREPs are solely dependent on pilots’ reporting; the information is often extremely helpful and sometimes critically so.

4 Checking Weather and the Big Picture The flight begins when we start to think about the weather, look over the data, and scrutinize all the information available from the multitude of sources we have already talked about. But in this world of electronic weather information, there are many more places to look. A standard weather briefing aside, what is a basic, commonsense look at what we check and how—before, during, and after flight? 1. The big picture—the synoptic. Start this a day or so before, using computerized weather maps, which make this easy but detailed, and calling the FSS for an Outlook Briefing. Barring this access, we can watch television weather. 2. The forecasts—airports en route, departure and destination, area forecasts, upper air winds and temperatures, and outlooks for ice, turbulence and thunderstorms. 3. The latest hourly reports (METARS) and then past reports—what has it been doing and what is it doing compared with the forecast? 4. In-flight—keep alert to the situation by obtaining current reports—what’s actually happening, forecast revisions, SIGMETS, AIRMETS, PIREPs, and what you see out the window. Listen to other aircraft on EFAS and Air Traffic Control (ATC), being alert to any problems they are experiencing and the weather information they are requesting. Listen to ASOS/AWOS/ATIS for airports you are flying over or near, checking to see if their reports conform to the forecasts. If data-link weather information is available, keep tabs on radar, satellite, and so on. 5. Manage the flight with the information, and be ready to take alternate action. 6. For learning purposes, and to build experience, take a moment after landing to inspect what happened in relation to what you thought would happen before takeoff. If possible, talking about the flight with the FSS or NWS is worthwhile and justified; they may appreciate it, because you can tell them what’s actually up there.

The Big Picture As noted, our number one weather briefing interest should be the big picture—the synoptic—which tells us the orientation of fronts, highs, lows, and other general

weather. Often during a briefing, the synoptic is passed over as we eagerly look toward the “actual” weather. This isn’t smart, as the synoptic should be thought of with care, as it is the foundation on which we build our weather picture. It should pose questions such as: Where does my flight route pass in relation to the fronts, highs, and lows? How would changes in the picture (speeding up, slowing down, or stalling of weather movement) affect my flight? What kind of weather do these fronts and systems have? Ice, thunderstorms, low ceilings—what do they mean in relation to our equipment and ability? And what about the synoptic’s past? Has it been behaving as predicted, or has it been inconsistent? In studying the synoptic, it is important first to see an actual picture. If we do not have maps and charts, 1 it is difficult to try and create a picture by either grasping text descriptions of the weather layout as we read it from a computer, or writing it down and picturing what is being told to us by an FSS briefer. Adding to this difficulty is the special language computers use in describing weather and its location; a language developed for convenience to the computerized system, not ours. Yes, today’s computerized weather information often has the ability to decode its unique language into normal text, but total dependence on this is not prudent. This cryptic jargon is something we must learn well, whether for understanding text weather should it not be decoded—yet may be critical—or also for using it as a kind of shorthand when writing it down, as when heard over the telephone or radio. It’s particularly confusing when the cryptic message “defines” the location of, say, a line of thunderstorms or fronts, by reference to a series of obscure station identifiers that are, at best, only vaguely familiar. For example, try making a synoptic picture in your mind of the following actual message from the Dallas Area Forecast; first will be a synopsis of the general weather setup—highs, lows, and fronts—then a regional forecast for Central and Eastern Oklahoma. (They are copied verbatim from the actual forecast, but we’ll add a translation under each one.) DFWC FA 101945 SYNOPSIS AND VFR CLDS/WX SYNOPSIS VALID UNTIL 111400 CLDS/WX VALID UNTIL 110800…OTLKVALID 110800 – 111400 SYNOPSIS…TROF OVR WRN TX BY 14Z OVR S CNTRL TX. BY 00Z CDFNT WL MOV OVR OK/TX PNHDL-SERN NM-FAR WEST TX BY 14Z OVR SERN KS-W CNTRL OK-W CNTRL TX. [The Dallas area forecast was issued on November 10, 2012, at 1945Z, and is valid until November 11th at 1400Z. (Month and year not in actual data, but added here for originality sake.) The clouds and weather forecasts run until 0800Z on the 11th, but the outlook is valid from the 11th at 0800Z until the

forecast ends on the 11th at 1400Z. Synopsis … at the time the area forecast began, a trough is over western Texas, and by 1400Z it will be over south-central Texas. By 0000Z on November 11th, the cold front will move over Oklahoma and the Texas Panhandle through southern New Mexico and Far West Texas. By 1400Z, the cold front will be over southern Kansas through western-central Oklahoma through western-central Texas.] OK CNTRL…SCT045 SCT150 SCT-BKN CI. 03Z BKN050 TOP FL180. ISOL-TSRA. CBTOP FL400. OTLK…VFRTSRA 09Z MVFR CIGTSRA. ERN…SCT040 SCT150 SCT CI. TIL 00Z WND S 20G30KT. 04Z BKN040 TOP 080. OTLK…MVFR CIG 10Z TSRA. [Over central Oklahoma … clouds scattered at 4,500 feet, scattered at 15,000 feet, and broken cirrus (that’s way up high). At 0300Z clouds broken at 5,000 feet with tops to flight level 180 (18,000 feet). Isolated light thunderstorms and rain (a light thunderstorm is still a thunderstorm and should be avoided—ROB). Thunderstorm tops to 40,000 feet. Outlook is for VFR with moderate thunderstorms and rain. By 0900Z marginal VFR conditions due to ceilings and moderate thunderstorms. Over Eastern Oklahoma … clouds scattered at 4,000 feet, scattered at 15,000 feet, and scattered cirrus. Until 0000Z, wind is to be south at 20 knots. Gusting to 30 knots. AT 0400Z, clouds become broken at 4,000 feet with tops to 8,000 feet. Outlook … marginal VFR due to ceilings and after 1000Z, moderate thunderstorms and rain.] While a rough mental picture can be created, the details are missing, and that’s a lot of information to stuff into our heads. As the old saying goes, there’s nothing like a picture, and in this case an actual surface weather map. If a map has been seen before the above synoptic information is read or delivered to us over the phone from the FSS, the text or telephone description makes better sense. In the text-weather example above, we note that although thunderstorms are not forecast in eastern Oklahoma until 1000Z, they are forecast to begin in central Oklahoma at 0300Z. This is a clue that tells us to check for developing thunderstorms, comparing time of development to the forecast. In the above example, an excellent enhancement would have been Next Generation Radar (NEXRAD) or even a relatively current satellite image. Now we would have a picture of actual weather, making our thunderstorm check easier. But let’s say we don’t have NEXRAD. We’ll say our flight is heading into Oklahoma City (in central-eastern Oklahoma) from the northeast, kind of partially paralleling the approaching cold front. We’re planning to arrive about 0400Z. We are kind of tight on time for missing the thunderstorms, but this evening that’s the way our schedule worked.

Suppose we are flying on instruments without radar or at least a lightning detection system, 2 feeling smug because we expect to get there ahead of the thunderstorms. Then some information from Flight Watch, ATC, or a new Convective SIGMET tells us of an earlier development or weather movement, alerting us to thunderstorms popping up ahead of schedule. It’s a double concern with respect to running into storms; one is the concern of beating them into Oklahoma City, and the other is meeting some activity ahead of the front, which may force us east and away from our course, as well as our destination. Suddenly we aren’t so smug anymore, and it is time to think about avoiding untimely thunderstorms as well as checking our destination weather, consider time en route, fuel, and possible diversion. Also, being on instruments around embedded thunderstorms, without radar or a lightning detection system, isn’t a happy situation! So now that we’ve tested our mental geography, let’s look at a sample surface chart, on page 34, for our above example.

Synoptic Surface Chart valid at 0000Z on the November 11, 2012 … the corresponding map for the forecast above. Now we can run through the synopsis again and see that it corresponds pretty well, especially the 0000Z forecast for the cold front position. The trough (the dotted line into Mexico) seems to be a bit behind and must rotate into Texas to follow the forecast. The weather north of the Dallas Area Forecast is covered by the Chicago Area Forecast, which we’d call up if we were going that far.

With the real picture in mind we see the orientation of the frontal systems, which makes it easier to relate those thunderstorms to an actual geographic location. We would know that the development of thunderstorms “after 03Z” will be dependent on the movement of the fronts, and for that matter, the whole system of fronts, highs, and lows. By obtaining current reports as we fly and keeping tabs on how the weather is actually moving—faster or slower—we can apply that knowledge to the 03Z forecast and determine how we stand. If we do not have access to a printed surface map, we can draw weather maps, crude and simple though they may be, sketching the confused messages of fronts and storms on our navigation charts or a small blank copy on a flight plan form. We have used plasticized Weather Advisory charts, either purchased from pilot supply stores or copied from the NWS website’s “AWC Advisory Plotting Chart.” Those “not for navigation” plasticized maps used for airline passenger announcements have enough aeronautical data to make them useful for grease pencil sketches of convective SIGMETs, turbulence areas, and synoptic setups. In today’s world of easily accessible weather information, it seems oldfashioned and improbable that we would not have some sort of synoptic weather image, or for that matter, any map or chart product. With graphic presentation of maps and charts, thunderstorms through NEXRAD, and all sorts of other information, we can easily form a big picture concept. However, there are times we may not have this big-picture weather information, which makes it harder to have solid planning for options before we begin our flight. We have to become very clever with voice weather information en route and having good old-school “in our head” imagination of geography and the synoptic weather concept, which used to be the only way and, for some, still is the case. That’s okay, as long as we’re sharp in doing so. The problem here is not having the total mental picture correct, then flying up to a “wall” of weather problems, while at the same time being trapped—unable to turn back or escape and in the middle of something we can’t handle.

No Surprises With this big picture in mind, plus carefully monitoring its movement—especially in today’s world of so much available weather information—we should never have surprises, get caught in nasty situations, or have to use that timeworn alibi: “The forecast wasn’t any good.”

Satellites and Some NEXRAD Satellite and NEXRAD weather images can be of huge help. We ought to talk about them as an accessory to the total answer of big picture weather. They are an excellent addition to the many sources of computerized weather information.

First, satellite images are not the actual raw photo but are enhanced by various processes. This isn’t something bad. It actually improves the picture, but different methods make the pictures a little different. Infrared is used to give temperatures of the clouds. That’s how meteorologists tell tops, but sometimes, with snow cover in winter, the information is difficult to interpret. If the image shows no clouds, we’re looking at ground or sea temperatures. Water vapor satellite images display water vapor quantity in the middle to upper troposphere, (700–200 millibars [mb], or about 11,000 feet on up to about 39,000 feet). This is not precipitation, but moisture hanging around in our atmosphere’s make-up; water vapor satellite image’s best use is showing movement of weather systems, jet streams, and thunderstorms. Both IR and water vapor can be seen as a night image, but regular visual satellite, like our eyes, sees nothing at night. Satellite images, like weather maps, have to be related to time, and the most value comes from the latest picture. When we look at commercial TV coverage and satellite images, the time the images were made, which should be shown, is generally unknown. However, with aviation weather services, the image time is given which not only allows important comparison with forecasts, but also function as a check on the time maps and images that were produced versus when they were made available for our viewing. For example, look again at the map on page 34; although a surface map (analysis), this concept is important whether a map or satellite image. It was valid at 0000Z, but was not issued until 0122Z, so the data on the map is an hour and twenty-two minutes old, when we first see it. That delay under a big sleepy high pressure is one thing, but the position of a fast moving front or squall line could be critical. So on surface maps where we are evaluating data for the present, it really isn’t. This time issue is important, will come up again in the book, and is the reason we need to check actual current weather to jump this time gap. With satellites this delay is less, but never the less worth noting. And NEXRAD delay? That’s a big deal, which is discussed in Chapter 15 on thunderstorms. When we add NEXRAD to a satellite image and/or surface map, we’re really getting a complete picture. Since NEXRAD is a “look from above” of precipitation, just as is a satellite image, we get an overall big picture view. However, after that moment of observation, it has changed. More on that will be mentioned next.

What Do Satellites Show? We see that satellite images show cloud cover and, to some degree, how thick the clouds are, but the pictures do not tell cloud bases or ceilings, and they don’t tell the height of cloud tops, although satellite experts say they can tell top heights within 2,000 feet. Infrared image plays the big part in this situation. The images also show convective activity—thunderstorms—as bright white blobs and lines in

daylight or by infra-red at night. However, when this occurs, NEXRAD or Radar Summary charts give a better idea of thunderstorm areas. NEXRAD is timelier than the Radar Summary chart; the latter has worked for years and still can if we don’t have other sources. Both NEXRAD and radar summary charts can give us data on storm heights and directions, defined areas and lines, and so on. The big advantage to NEXRAD is that it’s so easily displayed, from many potential sources, both before our flight begins and in-flight via data link to aircraft with electronic display capability. It should be remembered that this combination of images, charts, and digital electronics is a good reference for planning how to avoid an area of thunderstorms, but in no way should it be used to weave through a mass of thunderstorms; this takes airborne radar, maybe further enhanced with NEXRAD and lightning detection equipment as supplements.

An infrared satellite image at 0200Z on November 11, 2012, two hours after the surface chart on page 34, and valid for the time-frame of the earlier area forecast example.

A NEXRAD image for 0215Z on November 11, 2012, again about two hours after the surface chart on page 34 and respective area forecast. The infrared satellite and NEXRAD images, along with the surface chart of page 34 and the area forecast of page 33, gives us a full picture of what’s going on. In our flight example, we see the cold front is about where it should be per the area forecast and extrapolation of the surface chart, but it is drier into north Texas and on south. That low pressure on the border of west Texas and Mexico rekindles some weather. There are thunderstorms in west-central Oklahoma, verified with tops about 37,000 feet; but that’s then, and could be changing rapidly, because those wind arrows say some storms are moving faster than 30 knots, which is a cause for concern. We’ll talk more about storm velocity versus severity in Chapter 15 on thunderstorms. The satellite image shows some lighter shade cloud near Oklahoma City and a dim echo on the radar; maybe it’s something forming ahead of the front, so we need to keep our eyes open. The bright white of the satellite image into central Kansas and eastern Nebraska indicates a line of thunderstorms. Potential thunderstorms extend all the way north along the front, to that low pressure in western Minnesota. We can see the less dense cloud turning west, probably lesser activity associated with the trough shown on the surface chart, extending northwest from the Minnesota low pressure. There is a lot of moisture slinging counterclockwise northwest of the low, and the brighter the white, the thicker. If cold enough, there is ice potential, and NEXRAD also shows some tops, so there’s convection in one form or another. There is also quite a bit of less dense cloud color—lower tops—maybe a few hundred miles west of the front, over the western Dakotas and Nebraska. That’s typical backflow around a low and

probably a stratocumulus deck, with tops possibly approaching the teens and again, if cold enough, icy. This comes up again in Chapter 16 on ice. We see other activity north of the stationary front to the east across the Great Lakes, and again some higher tops are shown on the radar. That’s another story, and it’s a big country. Overall, with this satellite and NEXRAD data being for the evening, we see most thunderstorm activity as being caused by frontal effects. If it were daytime and warmer, along with frontal effects, it might get real spicy— something to think about if we’re heading back east the next day. The gray scale across the top of the satellite image shows temperature and therefore cloud tops. Dull gray is probably lowish stratus, as mentioned earlier, while bright white indicates very high tops—again, that thunderstorm indicator. What are the best uses for satellite imagery? First, they confirm what the weather map is saying. The clouds of the satellite image should corroborate the weather map’s structure, and it should be easy to pick out front locations as well as post-and prefrontal cloud masses. If the picture and the map do not match, then it’s time to dig deeper and learn what’s wrong. The first thing to check is how close the times are between the satellite image and the weather map. If the weather map and satellite picture have been produced many hours apart, this could account for the differences. If this isn’t the problem, then we should be suspicious that the weather isn’t working as the map and forecast indicated it would. We talk about this concept later, but basically it’s a job of checking actual reports against forecasts. Frequent satellite images give us an opportunity to study a series of them, seeing how the weather has moved over a period of time. With this capability, pilots can see if the weather is moving off course or becoming thicker and clobbering the route we plan to fly. With today’s computerized weather, this issue is enhanced by “looping” of the satellite image. For that matter, modern computerized weather loops everything: satellite, NEXRAD, and just about every map, chart, or graphic out there. That’s also what they show on TV. However, when we loop weather using a computer or personal electronic device, we can slow images down or use stop-action to better analyze whatever we’re investigating. We again look at the fact that satellite looping is what has already happened to the weather and not what will definitively happen in the future. What we see in this past image is the direction of weather movement, trends, and timing—fog dissipation, growth or dying of convective weather, but most importantly the overall flow (winds aloft) of weather systems, high and low clouds, and so forth. It is this visual rhythm of the sky, from which we can sketch a fairly decent forecast, whether on paper or in our heads. This can give us fair judgment of what will influence a flight. Actually, it seems sometimes it is easier to memorize an image in motion rather than a stationary one. A great education is watching the

looping of different weather setups, at different times of day, then comparing them with forecasts and “the big picture.” There are certain sources of “forecast” radar, which could really snare the unwary. It is just that—a forecast—and not to be depended upon as actual future convective weather. It might have fair possibility of accuracy to an overall area of future convection, but the reality is that convection/thunderstorms are where they are when they happen. To guess or assume otherwise is dangerous game. For the VFR pilot, satellite imagery is especially useful, because the pilot can then see where there are clouds and where it is clear. If the flight is over a long distance, the satellite picture can help the VFR pilot plot a course around all clouds, again enhanced by looping, and tells where the weather may be headed or changing. Just remember, we need to be open to change, since it is a guess from the weather’s past movement. If the VFR pilot finds it necessary to go through an area where the picture shows clouds, then it’s a job of checking actual reports such as METARS, ASOS, AWOS and so forth to see what those clouds are doing to ceilings and visibilities, then—very importantly—what they are forecast to do. There is a lot satellite imagery can do for us, whether we are flying IFR or VFR. Besides the previously mentioned convective weather, general cloud structure and air mass flow, we may see areas of fog, lenticular clouds lined up to show mountain wave conditions which give us hint to strong winds producing turbulence, and in cold weather, potential ice-producing clouds, just to name a few. Back in 1974, your two authors used satellite images while flying a Cessna 402 across the Pacific Ocean to Australia. The mid-Pacific stops were exotic atolls and islands, but lousy on weather information. For some reason of South Sea mystery, once beyond Honolulu, we could only get faxed satellite images and some printed weather. At Tarawa and Guadalcanal (yes, for real), the airport facilities were small offices with a lonely fellow who was obsessed with correct completion of the then tortuous International Civil Aviation Organization (ICAO) flight plan; my father was mysteriously absent every time we had to fill it out. This all in between the fellow turning around to a high-frequency radio and working static-infested communications with someone hundreds of miles away, giving an aura of exotic oceanic aviation decades earlier; and exactly my father’s point of the trip! Anyway, the satellite images let us look at the synoptic picture and some wind verification over a time sequence. Fortunately, the mundane weather of the central and south Pacific, during that time, helped make the satellite guesses pretty much dead on. When using satellite images, pilots learn more about them and the techniques for deciphering them. Asking questions of a meteorologist, if we are lucky enough to see a real one, will improve our knowledge of satellite images’ usefulness. Despite the earlier sea story, it is important to remember that these images are normally not the only weather information available and should not be used alone

to make decisions. We still need forecasts, actual current reports, and all the rest, including weather maps and charts.

Valid Old Map Thoughts As mentioned previously, before computerization, hence printable or constantly accessible maps and charts, if you wanted one to carry along on your flight, you had to be creative; this is where one would draw a weather map on a napkin, flight plan, or your navigation chart. Also, if you could not get a forecast map, but had previous maps showing a weather system’s speed of progress, you could estimate its future path. Tracking time of weather movement, which gave a wag on what was ahead. In 1965, I (RNB) stood in a weather office in Buenos Aires looking things over for a flight to Christchurch, New Zealand, over the South Pole. Since that wasn’t a regular route, the weather information was slim. The only weather map covering the other side of the globe was a day and a half old. We made an educated guess. Nieut Lieurance, the weatherman with us, guided our guessing, and he thought a front would go through Christchurch six hours before our arrival. He hit it almost on the nose, and after a 14-hour flight, we arrived over Christchurch in sparkling, clear air washed clean by a recent frontal passage. Not the way we like to do business, but much better than nothing. The big picture had told the story. While again it would seem rare these days to not have some sort of portable weather map, it does happen. I (ROB) have always been an avid user of daily and accurate newspaper surface maps. The New York Times was a favorite, with a mid-week and weekend series of forecast maps, including a jet stream outlook. (The Penn State Meteorology Department still provides the Times ’ fine maps.) Torn out, the little pieces of newspaper lived ready for action in my uniform pocket. Antiquated, yes, but the point is, if we want a map and can’t get to a computer or TV, we can look for good newspaper maps with fronts, highs, and lows, not cute little clouds with sun or lightning bolts. The point we are driving home is not to let our aviation endeavors get too hung up on technological peer pressure or seduction, throwing out proven methods just because it’s oldfashioned, especially when the new era doesn’t produce something we need and the old can provide it. Common sense and simplicity can still go a long way. Anyway, the best part of carrying a newspaper weather map on the airline was pulling it out and giving it a serious study when the FAA or a check pilot was in the jumpseat.

Where We Find This Computerized Weather Today, however, it is more than likely we have some form of graphical weather

display, from traditional surface and upper air charts, to in-flight warnings, area weather, forecasts, convective weather, icing, turbulence, and a lot more. Also, much of this data can have that looping mode to give rhythm to the sky; remembering looped data is what has happened versus what is supposed to happen whether it’s a guess off looped data, or published forecasts. We also remember that the shorter the forecast, the more potentially accurate it is, but not an exact look towards the future. The weather is only exact when we are in it. So where do we get all these weather graphics? There are a lot of computerbased products, from many different sources, whether retrieved off computers, dedicated electronics or personal electronic devices. The most consistent sources, as mentioned earlier, are the National Weather Service and their web-sites of the Aeronautical Weather Center (AWC) and Aviation Digital Data Service (ADDS ). They offer a complete menu of maps (charts) and required aviation weather data. Then, through the menu of these sites, we can dig into an almost endless path of information and tutorials. We also like referencing the Weather Prediction Center (WPC ), formerly called the Hydrometeorological Prediction Center (HPC ), with its website offering more detailed maps and forecasts; HPC supplies a lot of the data that feeds the NWS. The Storm Prediction Center (SPC ) focuses on mostly convective-related weather (thunderstorms), adding detail to what they provide to the AWC/ADDS sources. (Refer to the Suggested Reading section for access to the above websites.) When we access flight briefing websites such as DUATS/DUAT and the many other application-based products on personal electronic devices, they include various maps necessary for our briefings. If, however, we want further detail, we again encourage use of the above references. However, like so much of today’s computerized information, there is extensive data available and numerous sources for it, far beyond the space and scope of this book. This will come along as one delves into the study of weather, but we do recommend the earlier mentioned joint FAA and NOAA publication of Aviation Weather Services Advisory Circular AC 00-45G as the official explanation for the core of the government’s weather maps and data. It’s available on the Web at www.faa.gov , but a printed copy for quick and easy reference is always helpful; these are available from aviation supply sources. A few thoughts on television weather. It certainly is not any sort of approved weather—primary product or otherwise—but it is something many pilots watch, so it seems worth mentioning. With today’s weather-dedicataed TV channels such as the Weather Channel , and many local stations presenting fairly detailed weather, a look at their surface maps, radar information, or satellite images can be a worthwhile, big picture glance. The only problem, as said before, is verifying the time and accuracy of these presentations; this isn’t always easy to do. A good place for TV weather is when you are running around the house or hotel room, getting ready to leave for a flight. It’s best used as a heads-up situation, after

which we research official weather through aviation sources. One day, before the computerized weather era, I (ROB) took off from Atlanta into a summer afternoon filled with happy, low-topped, fair weather cumulus. The weather information had not mentioned any significant Convective SIGMETs; that system was still relatively new. However, when I was packing for the trip, the then-new Weather Channel had highlighted a potential line of thunderstorms percolating to the west of Atlanta. Remembering that black-and-white TV’s afternoon forecast map, we turned on the radar. Just as the radar lit up, a bright red line of weather lay not far ahead of us, and at the same time we popped through the tops of those fair weather cumulus, staring face to face with a wall of water towering into outer space. There was not much time to avoid it, so we told—not asked—ATC which way we were turning and did, avoiding a wild ride. Today we’d most probably be well warned from Convective SIGMETs, a good look at NEXRAD radar through some electronic device, calling the FSS, and yes, maybe the Weather Channel . Without some sort of electronic weather information or a phone call to the FSS, that TV weather might be very useful. A last thought on TV weather. When stations like the Weather Channel run episodes explaining weather phenomena, and all that makes them happen, we can learn quite a bit. They also run synopsis forecasts and long-range outlooks that can be quite helpful to that big picture of the weather; again, not official aviation weather but a good synoptic look. This is a great stride in making the public more street smart concerning weather. Television weather is worth watching, not only for what it has to offer, but hopefully to inspire us to learn more through personal study. For example, the constant discussion, explanation, and TV presentations of “weather modeling” are bringing us up to speed on what’s going on in the backrooms of our forecasting weather world. We can find these models ourselves on the Web at the AWC/ADDS/ HPC and other places.

Get the Picture First As we now realize, there’s lots of data out there to provide a good picture of the general weather. The key point is to get this picture and visualize it before setting up your weather briefing. Then it will be much easier relating to the data we retrieve from a FSS specialist’s words or what is divulged as we pick data off a computer or personal electronic device. This makes it easier for everything to soak into our heads. Now we have a total picture of what’s out there. Another point worth repeating is that if we use weather information that is not an approved product, such as TV weather, it should not take the place of a proper briefing! An important point.

On Days Off, Too

With weather information so readily available, electronically or otherwise, we can look at it daily. We have the opportunity to keep up with weather and be conscious of its movement and development, even on the days when we are not flying. This allows us to better judge weather and hopefully, become more intrigued and curious. A daily look at good weather maps, a decent TV weather station, or if really curious, some of those weather models, we can keep pace with the flow and development of how the sky is behaving, whether it is erratic or reliable. There is a cadence to the sky, so on the days we do fly, if we have been keeping up with things, it will be easier to pick up the action, understand the situation, and be ready for the demands it may place on us. The weather situation will be easier to cope with if we’ve kept abreast of it. This is all part of weather and flying being one skill. Suddenly, the sky opens up to an interesting world previously taken for granted and little understood. Aside from all that, it’s fun.

A Deeper Look at The Map What does a weather map show? First, we remember that the information is old when we look at it, and by the time we use the information, it will be older still. This is all a reminder that weather is always in motion, it moves and changes, and the movement and change are the things that make it necessary for a pilot to keep an eye on the action all the time. How many hours ahead we want the forecast to be is a key factor in determining how accurate it is or will turn out to be. Will the ceiling be above limits for the next hour? A forecast of that can be pretty accurate. Will it be above limits five hours from now? That’s more difficult to call, and the accuracy has moved from near 100 percent to something quite less. Will the ceiling be above limits five days hence? Now the accuracy is way down. So it is important to relate any weather information to the time it was forecast, the time of maps and satellite images, the time of winds aloft, and the time an actual report was made. Time difference directly relates to how confident we are, and the caution needed, in the use of any weather information. As mentioned earlier, a pilot should, as a habit, look first at the day and time noted on any weather information before considering it. We have another example relating to the Prognosis or “Prog” Charts, which are available off the NWS’s ADDS website. They give different forecasts—or prognosis, hence their name—of the surface weather over 6-or 12-hour time periods. We occasionally may see the same map validity time on two different forecast periods. Looking carefully at the bottom of the chart, we see that the “issued” time is different between the two, so one was created later than the other. That later one, obviously, is the important and more valid chart. However, we still look at the old one, comparing the changes, which tell us how the forecast has changed.

A weather map is like a snapshot. If the shutter clicked at 00:00 hours Z time, Universal Time Coordinated (UTC); that was the moment everything stopped, but at 00:01, it started up again, the characters moved in their own way once more, and the map you saw at 00:00 hours is no longer valid.

What isobars mean on a weather map. A weather map reminds us of a work of art; the sweep of isobars and fronts is graceful and pleasing to the eye, as is so much of nature’s work. But there is more than beauty; there’s also an important story. At first it may seem surface weather maps are confusing with all the numbers and meteorological hieroglyphics clustered around the various airport locations; these are known as station models. Actually, that information is mostly for meteorologists. What may be interesting for us in those numbers is found in the actual weather reports; METARS. There are important things we do want from a surface map. Most important is where the fronts, highs, and lows are located, and how the isobars curve, because they picture the wind flow and tell us from which direction it is coming. Isobars also tell us the velocity and source region, telling us from where the air is coming and what it’s like—cold, hot, wet, dry, stable, or unstable—which in turn tells us about the weather. When we see a deep low in the vicinity of British Columbia, with isobars on the westerly and northerly sides that sweep generally in a southeast direction and are packed closely together, we know immediately that cold, wet air is being swept into the area, and that it’s pushed by high-speed winds, because the closepacked isobars tell us the wind is howling. There will be lots of wet weather in the

area: low clouds and rain, with big snow in the mountains, and wind, lots of wind. During winter in New England, a low off the Maine coast will act the same, sweeping inland with easterly winds and blizzard-like conditions. Another day, another map. A northwest flow is over the Midwest, with the isobars coming from continental Canada, and we know the weather will be excellent, with fair weather cumulus and good visibility. A flow from the south and southeast in the center of the United States means hot, humid air is flowing from the Gulf of Mexico, creating thunderstorms. If a cold low of north winds is headed toward the Gulf, then the two air masses will meet as a cold front and that will make for very nasty thunderstorms and even tornadoes. This setup is unique to the United States—the cold winds that can flow southward from arctic regions without obstructions such as a mountain range, and the warm, wet winds from the Gulf of Mexico, likewise flowing unobstructed, toward the north. They meet like two warriors, and the wild mixing of these contrasting air masses makes our Midwest weather famous for its violence and changes. I (RNB) flew around the world looking for bad weather while doing weather research and never found any worse than in the Midwest of the United States. There’s not a geographic air-mass flow setup quite like it. In that first look at the weather map, we should notice the isobar trajectory and learn from where it brings the air and what that air is like—cold, hot, dry, or wet —and how large an area it has crossed that will modify it. The map on page 45 shows some features of a weather map in relation to the isobars. Notice the flow on the east side of the low. The air is coming from the Gulf region and will put warm, humid, sticky air over the eastern part of the country, with thunderstorms, too. Study how the isobars on various parts of the map show where the air has come from: the Gulf, warm and humid; central Canada—called Polar Continental —cold and unstable, bouncy, but good visibility. When inspecting any weather map, be extra wary when the wind flow pattern brings the air from ocean areas or large bodies of water—West Coast, East Coast, Gulf of Mexico, Great Lakes— and be watchful if you’re flying abroad, especially Europe or other parts of the world which have maritime surroundings. Oceans, large bodies of water, and in a micro-sense, even rivers, bring moisture. And moisture makes weather. (The Seine River wraps around the east end of Orly Field at Paris, France. Early-morning fog rising from the river often makes the east end of Runway 26 zero-zero, with the west end of the airport ceiling and visibility unlimited [CAVU].)

Wind flows and isobars above influence of surface.

Where the hot, cold, and wet or dry air comes from to make our weather.

Drift vs. high- and low-pressure areas in the Northern Hemisphere; reversed in the Southern Hemisphere. Isobars connect points of equal barometric pressure, but they also show the wind direction, because the wind parallels the isobars to make a picture of the wind direction pattern. The closeness of the isobars tells the wind velocity; if they are tight—close together—it will be a windy day. If the flight path is toward a lower pressure, drift will be right, requiring a left correction. Toward a higher pressure, drift will be left, requiring a right correction. This can be picked up with altimeter settings; if the setting ahead is higher, then you’ll be drifting left, and the opposite toward a lower altimeter setting. Of course, in the southern hemisphere, it’s all reversed. So it is the winds, along the isobars, that brings air masses to us. Arguments about what causes the wind and how all this movement gets started and pushed really don’t matter to pilots; we simply know that the wind-isobar pattern is transporting air and it will mix, heat, cool, climb, or get pushed to manufacture the weather.

What else do we look at when we see a weather map? There are two basic items: the pressure systems and the fronts. We look at them and visualize their movements and possible changes in relation to our flight path. Unfortunately, sometimes we overlook the pressure systems to study the fronts. We are apt to forget that a high-pressure area, sometimes called a ridge, is also a system, and not just a place between two lows. A high can often put out a lot of bad weather, and we ought to look at it with that in mind. Where the lows are is also important. The fronts are a part of them and move or trail along as the low does. It is important to realize how far we will be from the center of the low. A long cold front coming out of a low in Canada and trailing back to the southwest has different weather in different places along its length. The weather at Burlington, Vermont, will be different from the weather at Harrisburg, Pennsylvania, and that will be different from the weather at Greensboro, North Carolina. Each front has its own character, and the weather is always different as we progress along a front. There can be a lot of weather along a front or none at all—such as a dry front. Sometimes the weather can be ahead of a front or behind it, all of which means you have to study the big picture plus each front’s characteristics on sequential weather reports. Weather is more intense near the low’s center. In winter, the ice is heaviest, the cloud masses thicker, more confusing, and more difficult to top or fly between; in summer, the thunderstorms are wilder. If the flight path will be near a low center, we can be assured that things will be “interesting.” The frontal systems of a low are well known: a warm front, which generally moves south to north; a cold front, which moves northwest to southeast; and, as the low gets older, an occluded front, which rotates backward around the low. If the low moves, so do the fronts. If it keeps moving, its movement is easy to forecast, and a pilot will notice that things are working out as advertised. There are stationary fronts, too, which are what the name says—fronts that don’t move. They bring messy weather of fog and reduced visibility and, in summer, thunderstorms on a sporadic basis. These storms are difficult to see due to haze, fog, and cloud layers. Stationary fronts aren’t violent like fast-moving cold fronts, but they can cause problems due to low visibilities, especially at night, as well as early and late in the day. The thunderstorms, once formed, can be tough. Stationary fronts make a meteorologist’s day trying, because it’s very difficult to say when the front will move or whether it will just sit there.

Watch the Slow Lows Lows that slow down are the nasties that really ruin a forecast. There isn’t anything more difficult to figure out than a stalled front. If a cold front was supposed to go right through the East Coast but instead slows down and stops in the New York area, things go to pieces. Instead of clearing, the skies remain

cloudy; wind hangs limply around the southerly quadrant, getting over to the southeast perhaps, which can cause fog and low ceilings to prevail. With such a situation, a kink may develop on the stalled front, a wave may form, and a new low-pressure area may move up along the coast, following the stalled front’s line and putting out a lot of weather. What this means is that if a forecast calls for frontal passage at 20:00 hours, but the front hasn’t gone through by 21:00, it’s time to be suspicious. Actually, to prevent surprise, a good weather watcher will check a front’s movement as it crosses the country, noting whether it passes other stations on schedule. This way, a slowing or accelerating tendency can be discovered in advance. Which proves the importance of watching past weather to see how things have been acting. Sometimes past weather reports can be as important as current ones. Again, wind is important. If it doesn’t shift as expected, or its velocity changes, the wind has become a warning sign that something different is happening. Winds picking up generally mean things are beginning to move, probably getting wilder; the rain or snow will be heavier and the air more turbulent. The good part is that the front is on the move and finally will pass, but first there is the battle as it engulfs us. If the winds slow down in our frontal system, we can worry about very low ceilings and visibilities—perhaps lower than one can land in, at this stage of weather-flying art. Also, the low ceilings and visibilities can extend over a wide area. Depressingly, the slack winds are also a clue that bad conditions will prevail for a lengthy time.

The Wind Speed Tells a Story The difference between high winds and low winds and the resulting weather is experienced by pilots leaving the United States for northern Europe in the winter, a time when Europe has much fog. If winds are slack and there is little pressure movement, pilots worry and take lots of fuel, but if a low-pressure area is approaching the west coast of France, and Paris is forecasting 300 feet with rain and gusty winds, pilots are quite happy and fly off without much concern; there will be enough ceiling and visibility to get in. We become extra wary in slack winds and bad weather if we have one of the following: an airport near any body of water, such as rivers, lakes, oceans, swamps; flight late in the day toward darkness; flight toward mountainous areas; flight to a place where there is a lot of moisture on the ground from snow cover in relatively high temperatures, which creates a surefire fog condition; ground soaked by previous rain; and flight toward cities and heavy industrial areas.

Highs Are Not Always Nice

As we visualize a low-pressure area, we often have a dark and foreboding feeling; thinking of a high brings sweetness and light and a feeling of well-being. As we said before, it’s not necessarily so. Highs contain, on occasion, fog, ice, thunderstorms, strong winds, turbulence, and low clouds. Highs also bring things we may not worry about directly but should, such as high temperatures that affect our performance or, in winter, very low temperatures that make an altimeter indicate higher than it should. A high has all of these things, and many of them depend on where a low ends and a high begins. Our low ceilings and poor visibility in snow over the Allegheny Mountains come with a northwest wind, which we think of as the front of a high, although you might call it the back of a low. The unstable air that a high brings to western Pennsylvania will build a cloud deck in winter that often extends as far west as St. Louis. On the mountaintops to the east, the ceiling and visibility will be zero; farther west, where the air is older and modified, the tops will be lower and the bases higher. The instrument pilot will have a delightful trip on top, despite battling some degree of ice getting up there and then getting down again; VFR, it’s hazardous, and across the mountains impossible. Some of our wildest turbulence can be found in a high where strong westerly winds flow over a mountain range and cause standing waves—also known as mountain waves. Air-mass thunderstorms occur in highs. Most of them are scattered and easy to detour around, but a single thunderstorm becomes a major problem if it’s sitting right over the destination airport. To make it confusing, air-mass thunderstorms occasionally line up and, for a while, give the appearance of a front. The location where the back of a low and the front of a high meet is an important place. We tend to think that when the cold front has passed, the low is gone, and we’re now in a high, which means fair weather. Well, it isn’t always so, because the northwesterly flow on the front side of a vigorous high may be pumping in wet, cold, unstable air that’s often a continuation of the low and its messy weather. Highs, like lows, move, and when we see a high on a weather map that gives good weather, it’s worth visualizing that it is in motion and will depart. Then, what is behind it, such as a new low, will be moving in to take its place. High-pressure areas are often fog generators. The quiet, clear air near the high’s center will cool at night, by radiation, to its dewpoint; low land and valley areas may well be fogged in from early evening until after sunrise. How early, how late, and how much depends on the season of the year and how long the high has lingered over the area. Be especially wary of snow-covered ground with air temperatures below, but not too far from 0 degrees C. The air above the snow becomes saturated, and as the air cools with darkness, the dewpoint is easily reached, and dense fog forms to stay socked in for a long time. At certain times, Northern Europe is a great fog generator, because in the fall a high settles over it and often stays for many days. (It’s also one reason why

touring in Europe is best in late September and October—no rain.) But the flat high brings nighttime fog, and as the days become shorter, the fog burns off later and later in the day. In October, fog forms in the predawn morning and burns off by 9 a.m. or so, but by December, it forms near midnight and may not burn off until noon. Some days it never burns off, and I (RNB) once sat in Paris for five December days waiting for takeoff minimums! No particular hardship. So, while we’re sitting in the middle of a tranquil high, airplanes are having a difficult time landing and may divert to other European airports that offer better visibility. Many trips to Europe during these fall and winter highs gives their share of approaches below 400 meters visibility and some, at this writing, to 75 meter minimums for automatic, Category III landings. (Aviation minimums are measured in either meters or feet, usually depending on country of use.) However, when flying any approach to these stable but foggy conditions, a good aspect is that in such flat highs the winds are calm or light; there wouldn’t be fog otherwise. So whether automatic approaches or hand-flown to higher minimums, these instrument approaches are easy to fly because there isn’t any drift or shear. Europe is a prominent example, but these conditions have similar catalysts all over the world. The back side of a high—or we could call it the front of a low—has southerly wind flow that kills off the probability of fog, because the air is warmer, doesn’t cool off as much at night, and is moving. This inflow of warmer, moister air is where the afternoon air-mass thunderstorms develop. And this air, moving from the south, runs up over the back side of the colder dome of high pressure and begins the process of the warm front for the next low-pressure area. Milky, high cirrus clouds that dull sunshine tell us, in an upward glance, that this process has begun. So high-pressure areas need serious attention, too; what’s the wind, how old is the high, are we flying in its front, center, or back? It’s all important.

Look Up We are apt to only think of the surface map when, really, that isn’t where we fly. Fortunately there are maps drawn for where we do fly, in the sky above. These are often overlooked, and they should not be. They show wind patterns, velocities, and temperatures at different flight levels. They aren’t listed as altitude maps, but as pressure-level charts expressed in millibars (mb). (Actually, millibars as a name has been changed to hectopascals, which is used in altimeter settings, except for the United States, where we’re still using inches of mercury. However, reference to upper air charts has stuck with millibars.) Sounds complicated, but it isn’t, and all we need to think about is these millibar levels as altitudes. These charts of various levels start at 850 mb, which is roughly 5,000 feet. So, if 5,000 feet is where we fly, then a

study of the 850-mb chart will give a more realistic picture of what the winds are and what’s going on up there. These pressure charts are made for: mb

feet

850 700 500 300 250 200 150

5,000 10,000 18,000 30,000 35,000 39,000 45,000

There are higher charts for 100 mb and 50 mb, but they are not as readily available. Probably it is because we don’t fly up there, especially with the sad ending of that being the relm of the supersonic Concorde, but alas, some very high-end corporate aircrafts are sneaking up that way, let alone some spooky aircraft. The altitudes are approximate, because the maps actually show at what level, in meters, we find 850 mb, or whatever. So the charts, if viewed sideways, would undulate as the pressure levels do, reflecting lows and highs. All we’re doing in this little exercise is showing how the millibar-level charts relate to altitude and saying that if we’re flying near 10,000 feet, we should study the 700-mb chart and others for other altitudes. The locations of highs and lows are different aloft than on the surface. At high altitudes, one may not even see a low, because it’s all down underneath, and the 200-mb chart, 39,000 feet, may have the isobars in a straight line, with the low nowhere in sight. However, if it does show up at the 200-mb level, you can be sure it’s a lulu! The sequence of charts starting on the next page shows the changes between the surface and 300 mb. The surface chart has a deep low on the Canadian border west of Lake Superior. At 700 mb, 10,000 feet, we see the strong wind gradient on the south and southeast side. At 500 mb, 18,000 feet, the low isn’t as intense, and the isobars start to become more west-easterly. At 300 mb, 30,000 feet, the intense, tight circulation has smoothed out and started to join the zonal west-east flow. Most of the action is down low, and the 30,000-foot-plus jet airplanes will have little weather beyond ice-crystal clouds and probably some light turbulence. The charts illustrated here were drawn from actual charts for the same day and time.

Surface chart, beginning a series of four mb charts—same day, same time, different levels. These are available via the AWC and ADDS websites, and other sources. According to the 700-mb chart, if we were flying from Seattle toward San Diego, we’d have a constant left drift, because we would be flying toward a high and would require a plus drift correction, 3 although not much, because the winds are light along that route. We can judge the wind velocity by the isobars or the barbed arrows on the chart. Another point is that the winds at the 500-mb height tend to direct our surface weather movement. In other words, looking at those highs, lows and the front, we want to know where they’re heading, so a look at the 500-mb chart can give direction to our surface weather map. What we’re trying to get across is that those upper-level charts are very important, and not enough use is made of them. We should always consider which chart to concentrate on in relation to the airplane we’re flying: If it’s a small, single-engine we’ll look at the 850- and 700-mb charts, the charts up to 10,000 feet. For a turboprop or turbocharged piston aircraft, the 500 mb is the interesting one, because we’ll fly in the vicinity of 18,000 feet, although some of these airplanes are getting up above 30,000 feet. In a pure jet it is 300 mb and up. Of course, we take a glance at them all to see which way the lows are leaning, how deep they are, and what’s going on at other levels. Again, these charts are

important, because that’s where we’re flying, and we should know what’s going on up there.

700-mb analysis height/temperature (about 10,000 feet).

500-mb analysis height/temperature (about 18,000 feet).

300-mb analysis height/temperature (about 30,000 feet).

A Meteorologist’s Big Picture from the Web In previous chapter, we mentioned how beneficial it can be to have a meteorologist’s opinion of the weather. We also mentioned today’s challenges in getting access to various NWS offices and an audience with one of their meteorologists; again, not of their choice but that of bureaucratic decision. However, there is a computer-accessible product—a forecast—that we feel not only gives a good meteorologist’s view of the big picture, but is often pretty close to having that meteorologist’s personal opinion of the weather which we’ve harped on as being so helpful. Called the Area Forecast Discussion (AFD ), this is a plain language forecast that is produced at each individual NWS office, by their in-house meteorologists. (This is not to be confused with the aviation area forecast (FA). Also, since the acronym A/FD also refers to the Airport/Facilities Directory, in this writing we’ll refer to the area forecast discussion as “forecast discussion”; a term often used for it.) They offer not just a valuable meteorological discussion of the weather as forecast but also the why; this opens up subtle little inputs of phenomena that are causing the weather, giving us a better picture of the day’s sky. Often there is also comment on why the forecast might vary, which gives us that “IF” situation so important to aviation weather. The forecast discussion is usually interspersed with some technical meteorological jargon, but one can pretty easily pick out the meaningful flow of the forecast. At the same time, should we wish to learn more of weather, we can go into the NWS glossary and other sources to seek definitions of and information regarding terms unfamiliar to us—great weather education. A requirement of the forecast discussion criteria is to end with an aviation specific forecast, which is again written in mostly plain language, save reference to some familiar aviation terms and abbreviations. If we want to review each forecast discussion over our path of a flight, we need to call up each weather service’s individual forecast discussion along the route. Their forecast coverages are sometimes quite broad, so unless we’re flying a long-range flight, this isn’t too extensive a task. Also, some forecast discussions can be rather brief, often in areas where the weather is very good and straightforward. However, with the requirement for an aviation segment, we find that portion sometimes of more substance than the main body of the forecast, which is obviously to any pilot’s benefit. The area forecast discussion, in its total form, is not on the main menu of the AWC/ADDS Web site, which makes accessing this helpful resource unfortunately complex. However, typing in the city you wish to access in the upper left of the site will bring up that city’s weather page, and the forecast discussion has a blue link on the right side over a map of the respective NWS’s location. Another source is through the website of the NWS Southern Region Headquarters, which gives a

“click-on” map of the United States that allows us to access whatever NWS office we wish. We can access just the aviation portion of any offices forecast discussion through the AWC/ADDS Web site. In the blue column on the left, with numerous weather data subjects, select “Forecast,” click the words “TAF Forecast Discussion” and you’ll find a map similar to that mentioned above, but again, this one only sources the aviation portion of each weather offices forecast discussion. Lastly, we can also type “area forecast discussion” in the AWC or ADDS website source box. It’s a lot of stuff to just get a forecast, but sometimes that’s what we have to do in aviation. Cutting corners doesn’t work well in the business; and once we’re in the swing of it we’ll be glad we took the time.

1 . “Chart” and “map”: For the purposes of our writing, this refers to the same thing, as pertaining to graphic weather display, such as “surface weather map” or “500 mb upper air chart.” 2 . A “lightning detection system” displays thunderstorm activity by registering lightning discharge. For further information, see Chapter 15: Thunderstorms . 3 . In navigation, when you change heading clockwise, you increase your number of degrees, hence a positive or “plus” correction. The opposite direction, counterclockwise, decreases heading degrees, hence a “minus” correction.

5 Getting That Weather Information When we have the synoptic and map well in mind, remembering that the upper air charts are part of the synoptic, the next step is to study the weather in detail. We want to know what’s actually going on: the actuals (METARs), upper-level charts, satellite images, radar and radar summary charts, pilot reports, and forecasts. There is more, too. We also need to understand where to find this weather information, how it works, and how to keep up with its changes.

Always Learning Where and How As was said previously, there is constant change in the weather dissemination process, but in this day and age, we occasionally go beyond just modifying known products and methods. Today, we are seeing totally different concepts in these areas that not only need to be understood technically, but they also bring new concepts to how we gather weather information and conduct our flying. An example is NEXRAD. It changed the whole way we looked at convective weather, especially having equipment to detect the phenomena in the simplest of aircraft; overall a superb addition to aviation. However, with it came the need to understand not only what the service provided, but also learn how to use it effectively and safely. All said and done, it adds another layer in defining our weather flying. Most importantly, with such influential new products, if not properly understood and used, they can actually increase hazards to our flying. So, it is necessary to ferret through all this weather information, finding out what’s a change in an old product or what’s something totally new that requires extensive study and practice of usage. Either way, when these issues come around to weather services and all they offer, we need to frequently review what changes have been made and the extent to which we need to study and understand these changes. To this end, there are publications that are important in both the regulatory and operational arenas. The Aeronautical Information Manual (AIM ), under the umbrella of the FAA, is a definitive guide of how our aviation system in the United States operates and how we as pilots must function within it. The AIM is not a regulation, but it’s important that we consider it as a common operational practice so that as an aviation community we function with some sense of standardization. The AIM, of course, includes weather (meteorology in their term) which falls under Chapter 7 , interestingly titled “Safety of Flight.” Of course we

cannot forget the all-important Federal Aviation Regulations (FARs ). Both the AIM and the FARs are regularly revised, so keeping up with these changes is important. If we consult an FSS briefer or NWS meteorologist, we can learn how these changes fit into the system, which of course helps our understanding. Also, regular recurrent training with an up-to-date instructor can keep us aware of changes. Reading aviation magazines for a general idea of what’s new, as well as what’s on the horizon with coming technology or changes to regulations and procedures, is not only interesting, but almost a necessity. With that, we refer readers to the FAA’s magazine Aviation Safety Briefing , (either hard copy subscription or online via the FAA’s website www.faa.gov ), as a neutral complement to the many fine publications available. The NWS AWC website offers access to an instructional newsletter called The Front , and a Web-based tutorial on many weather subjects, called Jetstream . We highly recommend them. Also, memberships with national and international aviation organizations are helpful and important, with most offering excellent publications. Saved for last in this subject, but of great importance, is the concept that we have reached a stage of aviation technology and operation, and how weather is woven into the process, that needs more formal education. Arguably, we are late in this area. It would seem a solution is more proactive dissemination of weather education, both theory and how we use it, as well as equipment-and productspecific education. There are quite a few competent sources in this direction— some classroom-based and others via electronic media—that offer excellent and necessary education towards the flying environment, as well as increasingly complex aircraft and equipment. In summary: the responsibility for keeping current in all aspects of the flying world cannot be taken lightly. Those who have only a shallow knowledge will eventually find themselves in trouble.

Some Extra Sources With the advent of computerized weather, we have seen continued improvements of current weather products, as well as new efforts. One thing is for sure, these improvements and new products will just keep coming along. There are a few products we like that are helpful for obtaining weather information, or taking a broader look into forecasting that, until recently, were unavailable. Center Weather Service Unit (CWSU ): This is a weather product designed to assist the air traffic control system. It uses a map of the whole United States to show airports that report weather data; METAR and TAF for those which do so, and ASOS/AWOS airports as well. The airport symbol is a small “plus” sign, and by selecting each airport with computer mouse, we can find history

of past weather observations, TAF and METARs, PIREPS, graphical history of the past weather, Skew-T charts, and satellite images. There is also the NWS forecast page for the city of the respective airport’s location, and on the right side of that, we can reference the Area Forecast Discussion mentioned in the previous chapter. Also, if we click the cursor away from an airport, the national map will change to a more detailed map comprising that ATC center’s area, or hit it again for even more detail in high density air traffic areas such as New York, Los Angeles, etc. With the CWSU map on the computer, we can check various airports along our intended route of flight, getting instant METAR and TAF, as well as the more in-depth details. One of these is called the TAF Tactical Decision Aid (TAF TDA ), which is kind of an all-in-one page, as it relates to TAF and METAR data, with a color underlay explaining how the weather relates to conditions of VFR through Low Instrument Flight Rules (LIFR). This CWSU page, along with a good synoptic surface weather map, is a nice big picture overview. We can also chase around the map in a particular weather phenomenon, learning how it affects the weather at different locations. For more information, access the March 2010 edition of the NWS/AWC online publication The Front . The Suggested Reading section also lists website access for the CWSU. Models: We hear of these products almost daily on radio and television weather broadcasts, the latter often showing these models graphically, with coverage usually extending over a period of days. Models are the core of modern forecasting, along with the old-school sixth sense of sage and experienced meteorologists. Ironically, old-school meteorologists still feel there is a valid place for human input, versus excessive dependence on hightech instrumentation, automation, and data, which is the same argument of old-school pilots. You have heard and will continue to hear that song as our book proceeds. Models are made up of immense quantities of weather-related data that are massaged through extensive computerization. This data comes from satellites, radars, weather balloons, surface observations, aircraft, and more. The aircraft aspect is kind of interesting, with data of temperature, winds, and so forth being automatically transmitted from thousands of daily commercial aircraft operations. These models are revised frequently—sometimes hourly—which, of course, constantly updates their accuracy. As in any forecast, the longer the forecast period of the model, the lower the accuracy; but these things are getting pretty darn good. There are many model products available worldwide, which are linked through computerization. In the United States, a lot of the modeling information is produced through another NOAA affiliate—the

National Centers for Environmental Prediction (NCEP ). We can take a look at models ourselves, on the computer of course, which let us look into the weather crystal ball on our own time. It’s a good education and quite interesting. Model Output Statistics: There is also a model product quite helpful to weather forecasting at airports for which a TAF is not produced; it’s called Model Output Statistics (MOS ) and is part of the Localized Aviation MOS Program (LAMP ). This is a statistical forecast system that, as of this writing, is worked for around 1700 airports in the United States; that’s almost three times the number of airports that produce TAFs. MOS guidance is created through modeling, is updated frequently, and depending on which MOS product can reach out over 24 hours or up to a few days into the future. These forecasts are presented differently than TAFs, in a table-like format, with some data, such as cloud height, sky cover, visibility, and obstructions to visibility, supplied as a coded number relating to a range of visibilities and ceiling heights; the numbers correspond to the various visibility criteria from LIFR through excellent VFR weather. Model Output Statistics considers fluctuations that can occur in flight conditions, which gives us a kind of envelope in planning our flights. Also, graphical presentation of these forecasts, along with some probability input of the data, is also available, as compliment to the numerical product. These MOS forecasts are not approved primary weather product, but their data can be quite good. Their importance is related to the fact that TAFs are only valid for 5 statute miles around the reported airport’s center, and all else must be covered by the rather broad area forecast. With somewhat over 600 TAF airports, you can see there are lots of voids in individual airport weather forecasting. If we’re flying to an airport without a TAF, after we’ve checked the legal primary weather product of the area forecast, we can check our supplementary product of MOS. It effectively puts a forecast into many small airports previously without. Of course, we take it as any forecast, with that “what if” mindset. To learn more of MOS, its use, and how to read it, access this book’s Suggested Reading for websites accessing both MOS data and tutorials on how to read the data. We also recommend the June 2006 and March 2010 editions of the NWS online publication The Front . Skew-T log-P: This product has been around from the beginning of modern weather analysis. It is the core of reading what our atmosphere is doing, taking a vertical look—a snapshot—of temperature and dewpoint in comparison with the atmosphere’s pressure, which of course means altitude; all this is in relation to a specific location on the earth. From this, we can derive where

clouds will form, meaning we can predict cloud bases and tops, as well as the potential for phenomena such as thunderstorms, ice, fog, inversions, and so forth. There is also very concise upper air wind information from the surface to the troposphere. The data is displayed in a graphical, thermodynamic diagram called a Skew-T log-P diagram, also known as a sounding chart; there are others, but we’ll stick with the Skew-T log-P. To get this data, meteorologists launch and track weather balloons from, at this writing, seventy-two NWS locations in the United States let alone other countries. The balloons, which carry a transmitting instrumentation package, rise to upward of 100,000 feet, where they pop, after growing to the size of a small building. A little parachute returns the well-packed instrument package, with identification of its government status, in hopes of return and subsequent reuse. [The voyage of the balloon and its instruments are referred to as rawinsonde observation (RAOB ); they used to be called radiosonde .] The data is transmitted back to the NWS facility, where today it eventually winds up at the NCEP and is analyzed and presented in the Skew-T log-P diagram. Before the computer world, this data and the diagrams, along with the related weather forecasts from this data, were totally derived from balloon data. Now, however, the balloon data is supplemented by other sources, including the many data points from aircraft—mostly airliners—that transmit constantly updated temperature, altitude, and wind data through their advanced avionics. Also, satellites are looking down on us, reading similar data. All said and done, this relates to weather modeling and the ability to create Skew-T log-P information, and forecast data like the above-mentioned MOS forecasts, for those 1,700 airports and locations. With this wider variety of Skew-T log-P data, we can supplement data such as MOS, giving us a look at things like localized thunderstorm potential or cloud formation as it relates to an airport and its surrounding terrain. Another help could be seeing cloud and belowfreezing temperatures at our altitudes of flight; we can then consider icing conditions, and if freezing temperatures reach the ground, we know we’ll potentially be trapped with the phenomenon, with no altitude where we can escape it before reaching the ground! Skew-T log-P wind data is of close altitude spread, and as displayed on the chart, easily allows us to spot wind velocity and direction changes. That’s where turbulence and other wind weather–related issues can form. This is tighter information than from winds aloft forecast data, as that product can spread as much as 3,000 feet and over six hours; a lot can happen in those voids that Skew-T’s more current data can show us. And, if you’re a sailplane pilot, we can predict thermal height and strengths or tell how high we need to climb in our powered aircraft in order to top a good soaring day’s thermal turbulence. There is plenty more. Oh! where did that quirky little name “Skew-T log-P” come from? Well, the story goes

that the temperature (T) is plotted upon reference lines “skewed” at an angle, and the pressure (P) plot is not linear, instead somewhat logarithmic, hence “log.” A good start to learning more of Skew-T is the February 2004 issue of the NWS/AWC online publication The Front . There are also relevant website addresses in this book’s Suggested Reading section. Once we get into the swing of it, MODELS, CWSU, MOS, and Skew-T log-P can add an interesting, helpful and enjoyable aspect to curiosity of the sky. Refer to the Suggested Reading section at this book’s end for further resources on learning about and using these very interesting and helpful resources. National Oceanic and Atmospheric Administration (NOAA) Weather Radio: Lastly, we’ll take a trip back to low-tech, following that philosophy of not chucking out the past just because of what’s new. If we’re not glued to a computer or otherwise and want a feel for the day’s weather, most of us probably recall the NOAA network of radio stations, which continually broadcast local weather on frequencies from 162.40 to 162.55 megahertz (MHz). These are not specifically aviation oriented but give a good picture of the weather over an area of roughly 100 miles. They are changed three times a day, except if there is an emergency or sudden adverse weather development, when they’re changed immediately. There are about 1,000 stations around the United States, so most of the country is covered, and about 90 percent of the nation’s population is within range. Special receivers, some of which have an alarm that warns of any imminent dangerous weather, can be purchased inexpensively. These frequencies are also located on numerous hand-held aviation communication radios. There is one at the local airport where we fly, and it’s paid for itself. With no one staring at a computer and its radar, the alarm alerted us on more than one warm summer afternoon to an approaching line squall. There was mad rush to tie down aircraft, and the warning probably prevented aircraft damage as the wild wind and rain rushed in. Older technology, yes, but it works, prevents problems, and if you have ever been in a real weather emergency without other communications and dead computer and smart device batteries, this will give us timely, accurate information. Besides, like TV weather, if we want to get a feel for the day’s weather, it’s a nice way to connect while we run around our home, getting the day started or whatever.

A Skew-T sounding chart for Cincinnati Covington Airport (CVG) in northern Kentucky, just south of the Ohio River. Of the many lines are the ones from lower left to upper right—the “skewed” temperature lines, representing 10-degree temperature differences. The vertical of the chart is non-linear altitude in millibars left and feet on the right (hidden by wind flags). Wind is the graph on the right, showing typical wind arrows and velocity flags. Upper left of Skew-T log-P is wind path and velocity as compass orientation. The two squiggly lines in the middle of the graph are dewpoint on the left and temperature on the right. The temperature line going left is a decrease; going right it is an increase—an inversion. Other lines represent things like lapse rate, etc. The chart’s top legend says type of sounding, date, and time. Very important is noting where the sounding was taken; along the top legend we read “8.8 miles at 124° from CVG.” This can be an issue if around mountains, bodies of water, etc. Ground elevation is about 830 feet, and where the temperature and dewpoint lines are close or meet, we can expect clouds if there’s enough moisture. First at about 2000 feet above ground then again around 19,000 feet. At the same time, the METAR had a few clouds at 1,600 feet and overcast at 18,000 feet. A picture’s worth of many words.

No One Said It Was Easy It’s difficult to sort out the mass of acronyms, contractions, and coded information that invariably come with weather’s extensive resources and diverse amounts of information. Also challenging are the different and overlapping services. There are

many references to where we can hear weather on aircraft radios and find it on electronic access, both on the ground and airborne, while the sheer mass of data compounds the muddle. Here again, we recommend the AIM, this time the glossary and index, and the publication Aviation Weather Services AC 00-45G . The previously mentioned NWS/AWC website will also lead us to many tutorials and their own glossaries of terms. And the FAA website also addresses weather services, including, as mentioned in previous chapter, that of the ASOS/AWOS stations: where they are and their frequencies and phone numbers, along with the FAA’s airport facilities directory, which we can purchase with a subscription. With these publications and Web pages supplied by the NWS, FAA, and NOAA —the government—we’re dealing with aviation weather’s primary source of data in the United States. Also, with Canada our close neighbor, we should not forget their services, Nav Canada . Regardless of all these problems, the need for weather information is still there, and when you climb in an airplane and prepare to fly, it isn’t any different from the way it was when things were simple. It is important to mentally set aside the “modern” methods of communication—the confusion of frequencies, telephones, computerized sources, and mass of data—to clear your mind and focus on the gut things that count, like fog, ice, thunderstorms, ceilings, visibilities, wind, turbulence … the lot, no matter how it’s packaged. You must dig for information and ask questions until your mind has a clear picture of what’s out there and how it may or may not act. How do we sort it out? As we‘ve mentioned, FSSs give briefings of present weather, forecasts, a condensed synoptic, winds aloft, and any weather warnings in force. The NWS offices can give that important meteorologist’s opinion we talked about. Now, with electronically accessible weather, we can get everything we want, if we know where to get it, what to get, and what it means. However, as also said before, the weather given to the pilot presents a picture of weather straight ahead, down the course line. It tells little of the action off course, where fronts or other kinds of weather may be in motion to eventually create problems along our course.

Hired Help There are private meteorological services, where we pay for the service. These private services, however, are not just meteorological. They are full-service, flight-organizing, and in some cases dispatching services. With today’s complexity of aviation, especially international flying, they will file flight plans fitted to our airplanes, get all the international paperwork and clearances organized, and arrange for the all-important fuel, sometimes at special bulk rates, as well as many ground needs. However, back to weather, they can plug us right in to a meteorologist we can talk with about the weather and our flight.

These services are excellent, especially in packaging the whole works, a big help to busy flight operations with complex demands. Also, when we think of the reduced availability of weather briefers and meteorologists, these organization’s private meteorologists are appreciated professional help. If you are going to use one of these services, it is important to check that the service has meteorologists who interpret the data, massage it, and talk to you about it—just like the good old days. Without that part of it, it’s just a streamlined way of getting the data we can get ourselves; save, of course, the helpful organization of paperwork and facility needs. Of course, these private services cost money, and the average private airplane owner isn’t likely to add the extra costs when the government or our favorite electronic gadget supplies it. Interestingly, even pilots flying very heady aircraft, such as high-end corporate jets, can use their personal electronic devices with flight-planning applications to brief a flight and file the flight plan. If their operations are not complex, this is an astounding state of our industry. One concern, however, is that we hope this self-service ability to get our weather briefings and plan flights won’t inspire some aviation-unaware officials to reduce quality of the government weather dissemination, making the methods more impersonal, of lesser quality, and maybe less accessible, and the whole system less safe. However we do it, private service, computer access, FSS, NWS, or what have you, the game is the same. Pilots must ask the right questions, whether to a briefer or to ourselves, to have the proper picture and knowledge, in order to make the correct decisions to fly (or not) the weather.

Opening Remarks to the FSS—and Ourselves When FSS and NWS were the only weather show in town, the business had a colloquial feel, especially if you had an FSS at the local airport. Often, these facilities were a Saturday morning meeting place talking about weather, flying, and all that goes with it; we learned a lot. However, when away from our local FSS, especially when calling another while on the road, the key was not to glide into the office or pick up the phone and simply say, “Hi y’all, how’s it look to LA?” If we did, many briefers would tell us, just as unceremoniously, “It’s VFR” or “It’s not very good” or whatever. To get the weather we need, VFR or IFR, it was, and still is, very important to open the conversation with a professional sounding sequence of the appropriate information we need for a briefing. In this day and age there is a standard sequence of information the FSS likes in proper order; the big reason is for conformance of how they enter it into their computer, from which comes our briefing. It speeds things up for both ourselves and the FSS. Now the briefer knows what’s needed, not just of the flight, but with some sense of our limits as a pilot and aircraft. So the sequence is:

• • • • • • • • •

Type of flight: VFR or IFR Aircraft identification or our name Aircraft type Departure point Estimated time of departure Altitude Route-of-flight Destination Estimated time enroute

Now we pick up the phone and it might go like this: “We’d like a standard briefing for a VFR flight. Our aircraft is N-whatever, a Cessna 182, and we’re departing from Montpelier, Vermont (KMPV) at an estimated 1500Z, cruising at 6,500 feet and whatever route-of-flight to Elmira, New York (KELM). We’re estimating one hour and forty-five minutes enroute.” It’s important to say and spell the airport identifiers, as with the centralized FSS system we might be talking to a specialist in say California; it’s a big country! On the other hand, we can also request a specialist familiar with, in this case, the New England area, who if available will have better grasp of local weather issues, easing the briefing for both them and us. Also, the “Z” after 1500 means “Zulu Time,” the same as Coordinated Universal Time (UTC) which used to be called Greenwich Mean Time (GMT). So we have asked for the works, which is what we should be asking for, and now it’s time to pay close attention to the briefing. This learned approach on our part is professional, the briefer knows we’re serious and that we want a good picture of what’s out there—from synoptic to sigmet. Doing it offhandedly and informally can invite an offhanded and informal response and, for those very few briefers who might like to tell us how to fly, a chance to editorialize rather than detail the weather. Again, this is most likely an issue of the past, but if it happens we might find the pilot departing with a sketchy idea of what’s really out there. It may sound stuffy, but this is the time to be formal and serious! Since today’s FSS briefings are over the telephone, we again mention three thoughts to make it easier: 1. Check a computer, personal electronic device, TV, or even newspaper weather map to know the general weather setup—the synopsis—before our call to the FSS. 2. We shouldn’t be afraid to ask the briefer to repeat things. 3. Train ourselves to write down weather symbols so we’re using a sort of shorthand to copy what’s being said.

Synoptic Again So where do we start? We start with our old friend the synoptic, no matter where or how we get it. If we have a good mental concept of this big picture, we’ll know whether there are fronts on the move and troublesome weather stirring for our flight. We are trying to learn what to be wary of—weather speeding up, slowing, stalling, and changing to lower ceilings for landing. Possibly thunderstorms or ice are developing, then again they might already be in the picture—things that will seriously harass our flight. An important point is that if our synoptic homework was done well, we are in a position to ask, after the routine briefing, some searching questions about off-course weather that might worm its way onto route, making the day difficult. Where is the front that’s not scheduled to be over the route until after we’ve landed? Any chance it’s moving faster—fast enough to clobber the route while we are flying over it? How about those thunderstorms forecast for tonight—might they mature in the late afternoon, about the time we’re expecting to reach our destination? These are the important questions, and the protective intelligence to ask them comes from what we learn by scrutinizing the synoptic in advance.

Look Ahead Much in tune with the above is the wisdom, when getting a briefing, of asking for future forecasts—forecasts for the next period after our estimated time of arrival (ETA)—so we can keep an eye and ear out for the possibility of weather moving or developing sooner and giving us trouble. Such inquisitiveness backs up the basic fact that one should always approach weather forecasts with a certain amount of skepticism.

The Real Thing Now on to the actual weather reports—what is it really doing? These should be studied along the entire route, not just for the airport of destination, but for each reporting point along the way, so we’ll know what to expect en route. This is especially important for the VFR pilot, and even more important if there is rough terrain—mountains—along the way. The higher terrain will have lower ceilings and visibilities under conditions of poor weather. A scrutiny of the reports will give an idea of what to expect. There’s nothing sloppier or more hazardous than the pilot who simply asks: “Is it VFR?” and, armed with that, and perhaps winds aloft, charges off into the blue, flying from a position of ignorance. The study of the actual reports for airports along, behind, ahead, and to the side of the route for the latest and past few hours, is important for learning how the weather has been acting. To be thorough, a past forecast should also be looked

over and correlated with the actual weather sequences (METAR) to see how the weather has been, compared with what it was supposed to have been; this is far less difficult to obtain than in years past. When in the air, the weather we’re flying should be related to each hourly report, which should be gathered routinely and religiously while flying. The past reports, compared with the new hourlies, can give a strong insight to weather changing, developing, deteriorating, or, happily, getting better. This constant study, while flying, of the latest actual weather reports cannot be overemphasized. Equally important is the wily pondering of what’s changing, which sends signals that not all’s well in the sky. The key point here is that the actual reports should be gathered each hour we fly, then compared with the past hour’s report and the forecast. Obviously, if we’re flying across a big high and it is CAVU all over, we don’t have to check weather every hour, but the more inclement the weather, the more we have to be on top of it. It doesn’t hurt, on that CAVU day, to gather a report or two, confirming it’s really staying CAVU. There is always the possibility for surprises, and if the weather is that good, there isn’t much to do anyway. It’s only natural that our major attention is toward the destination, but there’s much to be learned about development along the way, especially if thunderstorms are in the forecast, as well as ice and turbulence. So again, attention needs to be given to reports for stations along the route as well as the airport we’re headed for. Constantly, however, we check the destination’s hourly actuals—METARS— to be certain the weather is holding up and not starting a downhill slide of ceiling and visibility. There’s little or no excuse for a pilot to arrive over the destination airport and be “surprised” by below-limit conditions. Actual weather reports, either the hourly METARs or Special Weather Reports (SPECI), which are issued when there is significant weather change between the usual hourly observations, are tremendously important. Because weather forecasting is not exact, and probably never will be, we need the actual reports to know how the forecasts are doing—is the weather as promised or something different? The actual METAR is the point of truth. All the forecast charts, maps, and reports we’ve seen are not real . They are only estimates of what will happen, and the radar charts, satellite images, are all what was, not what is, when we’ve seen them. Even data link weather graphics during flight are instantaneous pictures of the time they were taken, and we need to verify that time. With NEXRAD we have a time-delay issue that, as mentioned before, we’ll detail in Chapter 15 on thunderstorms. The METAR is the latest weather information at the moment it’s taken, but then it can be an hour before the next one, possibly significantly different when we arrive. Say we start an instrument approach with the weather reporting 200 feet and half a mile, within our limits, but when we get to 200 feet, the ground

doesn’t show up, and the ceiling has gone down since we started the approach. Now what are we going to do? What we’re pointing out is that finally the flight will be directed by the pilot in command who, we hope, understands that the real conditions affecting the flight are what is seen and experienced, not what charts, maps, or reports say. Now the pilot is in command, performing the best way possible, using whatever experience and skill is in that pilot’s background, to complete a safe flight. But in weather, gathering these things—the synoptic picture, forecasts, and actual reports—is the key. If this book only gets that across, it would be worthwhile. Many years ago, teletype sequences went west to east and south to north, giving actual weather reports in geographical order. To check weather, one read a tape of the reports, like the old stock market ticker tape. That was logical, because weather moves in these directions. You could observe a front moving toward the east as you read each station’s weather report in line. The wind would be northwest at Kansas City, but still southwest at Columbia, Missouri, and you knew where the cold front was—somewhere between the two stations. Or one could see a warm front progress from south to north, graphically, because the reporting stations followed the same path. Computers have taken over, and all this logical order has become history. True, this has been reintroduced in graphical computer displays, from which we want to make sure we conceptualize what’s happening. In other words, when we see changes in weather as it progresses along our route of flight, we ask “Why?”, in lieu of just taking it as an event. Then, of course, there are the times we don’t have that graphical display, of which an example is seeing computerized graphical display for briefing but not having data link graphics in flight. We need to know how to think those weather maps, just as we had to visualize the weather’s lay in the old teletype days. Today, when getting our briefings, we get the actual reports for stations along the route we’ll fly—not too far beyond or before or off course. It’s as though we’re looking down a route wearing horse blinders. However, what is beyond the station and moving toward it, or what’s happening with that front off to one side, and what was the previous weather compared with the forecast? These are all things a pilot should know. The information is available, whether we ask the FSS briefer for it or get it ourselves electronically; then we study the setup and its possibilities. This is necessary, and a pilot should have the discipline to do it. The present system will tend to make the lazy pilot take the route forecast and go with it—a good weather pilot will dig deeper. The pilot must keep digging until satisfied that there is good and sufficient information to tell the weather story. This can be difficult on telephone briefings, because the person on the other end of the phone may be pushed to get on to other briefings, as we ask for more information than the normal briefing gives. This is rare, but can happen. They are busy, but that shouldn’t intimidate us.

Years ago, I (RNB) was talking to a briefer on the telephone about weather from Philadelphia, Pennsylvania to Burlington, Vermont. He said it was all VFR. But from the TV map—no computers then—I knew there was a front to the west that could move on course if it speeded up. Asked about it, he said: “Oh, that won’t bother you. Your route’s forecast VFR for your time period.” Not satisfied, I started asking for actual weather reports at stations like Buffalo, Rochester, and Harrisburg in an attempt to learn where the front really was. The briefer became irritated and said rather strongly, “What do you want those stations for? You’re not goin’ that way. I just told you it’s VFR!” Although such an attitude is rare with today’s professional briefers, this example demonstrates how people get in trouble with a sketchy picture of the weather. That front was moving faster than forecast and did mess up the course, and I eventually had to file IFR later in the flight. Now, what about the VFR pilot new to the game and starting out on that briefing? Would they know enough to land? Turn around? Run east, or press on, getting lower and lower, with less and less visibility in mountainous country, thinking it ought to be okay because the briefer said it would be VFR? It’s the typical setup for a weather accident by pushing VFR too far. This also makes the point that a pilot cannot depend on a briefing being so accurate that the statement “It’s VFR” covers everything. Weather science isn’t accurate enough to do that, but the tendency of the system is to make it appear as though it is, and this means another adjustment in pilots’ thinking; they must not allow the official-looking maps, charts, forecasts, graphics, and briefings lull them into feeling that the statement “It’ll be VFR” is solidly accurate. Once we’re airborne and flying through the weather, in clouds, ice, thunderstorms, fog, or whatever, the authoritative appearance of the weather briefing quickly fades, as a pilot combats the weather and wonders what is this phenomenon that the briefing didn’t divulge—and what to do about it! Preflight study and constant updating will be the pilot’s defense, as well as an aid, when there’s a sudden discovery that the forecast—and the statement “It’ll be VFR”—are inaccurate, with the real world different and tougher! Of course, if we can access data-linked weather in our airplane, we can call it up anytime, easily keeping current. Otherwise, without data link weather in flight, a pilot should feel free to pick up the mike and ask for weather. We need to remember that getting weather information is the pilot’s job, and nobody is going to spoon-feed us. It is easily possible to be flying along feeling good about the world, never realizing there is some tough stuff ahead or at the destination. This euphoric, and dangerous, situation could exist simply because the pilot did not assume the responsibility of keeping up with the weather. Pilots should always remember that the route of flight or destination may have to change with the weather. It is folly to plug along without flexibility of thought and willingness to realize that one may have to fly differently, change route, go

IFR, divert, turn back, or even land. This is a significant point—being flexible. The fixation of plugging toward the destination, even though the weather has turned foul, has killed too many people. One should be ready and willing to toss aside the idea of “getting there,” in favor of turning away to a safe-weather airport. Important! These problems of gathering and studying weather information, we believe, are the genesis of more weather accidents than any other single factor. The system, along with aircraft flaunting equipment that tempts pilots to believe they can fly almost any weather, has seriously threatened the idea that pilots need to make weather judgments and at times respect the fact that their original flight plan is not going to work. As we’ve said again and again, a safe pilot must be a weather person, too!

6 Weather Details—What They Tell Us When we look at weather details, chances are that the first thing we’ll glance toward will be the destination weather. What is it, VFR or IFR, and how close is it to the legal limits? These details come mostly from actual reports like METARs and TAFS. Graphical weather may give us a good overview, but not the finite details of data we discuss in this chapter. So despite our marvelous world of graphical weather, this chapter helps reinforce why we still need clever, old-school analysis of weather reports. It doesn’t take too much soul-searching to judge if weather is within one’s ability and equipment. Basically, the flight can either be made VFR or it requires IFR, and marginal weather between the two can cause trouble. If it is marginally VFR, then the pilot had best be prepared to go IFR in case suddenly, en route, it’s discovered that IFR has become a necessity. Trying to hang onto VFR when things have deteriorated, and IFR weather is becoming more of a reality each moment, is a proven method of getting into serious trouble!

VFR—Not Easy If it’s decided VFR is going to be the way of the flight, then the pilot may have a more difficult decision than the IFR pilot. In many respects, the VFR pilot needs to learn more about the weather setup than the IFR pilot, because the VFR pilot must know if the weather will remain VFR from takeoff until landing at the destination. Sometimes this demanding decision is being made by the least experienced pilot! Either way, experienced or not, pilots should make the decision and not simply depend on a briefer’s statement, or our own weak briefing efforts, that “It’s VFR all the way.” When we do get our briefing from the FSSs, the statement that should get a pilot’s attention and be considered seriously is the briefer saying, “VFR flight is not recommended.” This comment creates a great deal of angst and frustration for pilots, and not being of a fixed criterion, other than the FSS briefer feeling the flight cannot be completed VFR or at least safely so, may sometimes be perceived as an unnecessary legality. However, standing in the FAA’s and FSS’s shoes, we need realize a briefer does not know our experience, how we think as pilots or orchestrate our flying. Second, they see something potentially compromising to the weather affecting our flight. What is most important when hearing the comment are two things. First, the statement is not binding and the final weather

decision is still the pilot’s. Second, “VFR flight is not recommended” should be a warning to dig even deeper for more weather information. Sometimes this will yield nothing, but that one time we do find something sketchy with the weather might just have been that critical event.

MVFR The Weather Depiction Charts, as well as various forecasts, digital presentations, and weather warnings, tell us of areas where conditions for IFR, VFR, and MVFR can be expected. It’s the MVFR portion that should be considered very carefully. It would be more realistic to change the label of MVFR to HVFR, which would stand for Hazardous VFR. Why? Because that’s what it is, hazardous! MVFR is defined as “ceiling 1,000 to 3,000 feet and/ or visibility three to five miles inclusive.” This can be dicey weather for VFR. Poking along, down low, especially in mountainous areas, with such reduced ceilings and/or visibilities is asking for trouble. If precipitation is falling, then it’s much worse, because threemile visibility with rain smearing a windshield reduces what you can actually see to far less than three miles. Imagine. We’re nervously sneaking through this murk in mountainous country, maybe a high peak just ahead, or in the seemingly safe flat lands, missing awareness or warning on an electronic flight display, or that map on our lap, of a communications tower dead ahead that reaches into the sky to a scary height. Suddenly, it appears out of the gray world—a hazardous way of flying. Ceilings are defined as broken to overcast clouds. This means scattered clouds can be floating around in the falling precipitation of an MVFR area below the 1,000-to 3,000-foot ceiling. So as one flies in the rain-reduced three miles, clouds can be encountered almost half the time, because scattered is defined as 0.1 to 0.5 sky cover. Bumping into these wispy pieces of cloud or twisting along trying to miss them can add to the difficulty of struggling to stay VFR. You can also feel nervous when it’s raining and lower scattered clouds are encountered, because they most probably will increase and become broken to overcast as the moisture of the rain raises dewpoint. Then, two things can hap-pen—the ceiling could become well below 1,000 feet with lower visibility, and we might just get stuck on top of this new, lower overcast (undercast) deck.

MVFR Is Not Static An additional and very important point is that MVFR areas are not static. The weather doesn’t stand still very often or very long. Remember, it is always in motion! Poorer weather may be on the increase, or things may be getting better. Either way it is tricky, because things can get worse sooner or better later than expected. The pilot planning to fly into that MVFR area needs to be very aware of

the weather prognosis and study it carefully before the flight, learning which way conditions for the MVFR area are forecast to change, up or down. Then, watch it carefully in-flight by gathering weather reports and looking through the windshield to see how the MVFR is behaving. Finally, what you see, or cannot see ahead, is the moment of truth, the real thing, the actual weather, regardless of the forecast. In VFR, there is little time for decision. One cannot keep pushing in hopes it will get better. The decision to turn and run or go IFR is now! One can lay down a basic rule that anytime you are headed into MVFR areas, you should be willing and able to suddenly go IFR. There’s no way of knowing, but bets are that MVFR displayed on weather charts has suckered people into flying areas where they should never have gone— and never came out.

IFR—Not to Worry The IFR pilot, and a properly flown IFR flight, doesn’t have to worry about clouds and terrain en route, because IFR flight is at safe altitudes above it all. An IFR pilot doesn’t fear flying in clouds—or shouldn’t. But the VFR pilot who does not have an instrument rating has a very strong concern not to get into clouds or areas of reduced visibility that do not give enough reference to fly the airplane and maintain control, as well as see what’s ahead. As said before, and because it is so important we repeat it, once a pilot looks at the weather and decides it’s good enough, the question to be answered is: Will it stay that way? To answer that, we look back at the big picture to see if weather is approaching in the form of a front or if there is air-mass deterioration. On the other hand, possibly and happily, a front has passed, indicating improvement, or the airport is near the center of a high that affords good weather protection on both sides. An exception may be early-morning ground fog, but that will burn off after sunrise. The destination, however, isn’t the only area of interest. We want to consider alternate airports for both our destination and departure points. Either VFR or IFR, we may want to return when still reasonably close to our takeoff point and should know whether the departure field will be accessible. If it isn’t, then we need an available airport where we can go in case of trouble—in the formal world this is called a takeoff alternate. The airlines, obviously flying IFR, are required to have a takeoff alternate if they take off when the departure airport is below landing minimums. This is figured over a maximum allowed time with an engine inoperative, a worst case scenario, but there are many other reasons we might return, most all of which also apply to light aircraft; things like system failures, doors open or more traumatic, fire. Airliners, corporate jets, and some turboprops are very redundant designs, but privately flown lighter aircraft, not as redundant

and of freer regulation, let us decide how far to stretch things; we need to exercise this opportunity with good sense. So, with regard to airport weather, we are interested in destination and alternate, as well as departure and departure alternate. If the destination is too bad, then a pilot wants to know when it is going to improve. What do we look at first? The forecasts. The best way of studying them is to check them over a period of time. We check for the current time—that is, what the forecast predicts for this very moment, then for the previous four hours, and finally for the period of our expected arrival and a few hours after that.

Test the Forecast With all this firmly in mind, we go to the actual sequences (METARS) and see how the forecasts have been performing. What was the weather during the previous four-hour period, compared to what the forecast said it would be? Then the present—what is it actually doing compared to what the forecast says it should be doing? Note how many special observations (SPECI) have been made. Specials show that something is different—changing—and should act as a signal to look closer and be alert to what the changes are. Now we have a feel for the weather, for the kind of weather it is, and whether or not it’s acting according to plan. If it hasn’t been acting as expected, we’d best look again at the big picture and try to decide what’s been going on. Are the fronts moving faster or slower, are the lows slowing, has a flow of air from the sea remained instead of turning around? The important point is to give the weather forecasts a test and see how they have been performing. Good forecast performance can indicate an easily forecastable situation. A bad forecast generally means a tough setup that has the weather folks guessing. We learn to look at forecasts with a degree of confidence based on their past performance. Once we have seen what the weather has done and what it is now doing, it’s only necessary to fill in what it will be doing when we get there.

The Late Weather There’s another point worth considering—what our airport is forecast to do after we get there. We should know the expected weather for a period of four hours after our arrival. This isn’t in case we’re late, although that could be important, but rather to give a picture of the trend. If, for example, the airport is forecast clear and unlimited for a long period after our arrival, we feel more relaxed about the chances of its being good when we arrive. If, however, it’s forecast to begin a gradual deterioration four hours after our arrival, then we keep an eye on the possibility of this deterioration occurring much earlier than expected. What we are doing is bracketing the expected weather for our arrival by getting the forecast for

before and after our arrival. What we do is slip the time of arrival, that we will really use, in between the current weather and the future weather, seeing toward which time, now or future, the weather is developing.

Regulations Aren’t the Important Criteria When checking our weather data, the first things we look at are ceiling and visibility. Are they forecast to be within VFR limits or will an instrument flight be necessary? This question involves the FARs, which say that you need a certain minimum ceiling and visibility to fly. These minimums are determined by regulations, but an important point about legal minimums is that they are a batch of words in a book and aren’t to be considered a substitute for good judgment. An airport may be forecast to be better than VFR limits and still not be a place to fly. Suppose it’s down in a valley surrounded by mountains that are cloud-covered; there just wouldn’t be any way of getting in there VFR. The legal minimums may not always be good enough for some situations. When looking at ceiling reports, remember that the ceiling reported isn’t for the scattered clouds, but for the broken and overcast. So if a ceiling is reported as 800 feet with scattered at 200, realize that you may have ground contact at 800 feet, but there will be annoying scud occasionally blocking your lower visibility. If it’s raining, you can bet that the scattered will become broken or overcast and become a 200-foot ceiling later on. Visibility is an important factor for all pilots, whatever their experience. If ceilings will be at or near minimums and the visibility is good, then we know it won’t be difficult to fly, but if visibilities are low, a minimum ceiling makes flying much tougher. If we are poking around mountainous terrain with low ceilings and low visibilities, we are in a difficult situation. A visibility of five miles with a 1,000-foot ceiling doesn’t sound bad in Indiana, but that same weather between Winslow and Kingman, Arizona, would be very hazardous and difficult. The same applies to the low approach. A 200-foot ceiling with a couple of miles’ visibility isn’t a difficult approach if turbulence and wind are reasonable, but when the visibility drops to half a mile, the approach is much different. Conversely, we can handle reduced visibility if there is a lot of ceiling, allowing us to get up high enough to clear all the terrain we cannot see. In practice, however, we prefer visibility to ceiling if we cannot have both. Whenever we consider visibility, we should note whether or not there is precipitation. Four miles reported by the NWS can be much less when seen through a rain-smeared windshield. Four miles may in reality be only one bleary, wavy mile. Airplane windshields vary in their ability to shed precipitation, and some are really awful. If we have an aircraft equipped with windshield wipers or any other effective system, such as pneumatics or rain repellants, this helps tremendously. When first dealing with this issue of rain on an aircraft’s

windshield, pilots may not think there’s any problem, because they can see through the windshield in rain. However, turn on that wiper or system, and suddenly there is a dramatic increase in what’s visible, making us realize we had been cheated out of a couple of miles of visibility with a rain-covered windshield. So the airplane windshield, and how well you can see through it in rain, becomes an added weather factor. Make this little test the next time you’re flying in rain, straining to see ahead: look out a side window that isn’t getting rain from straight on and see how improved the visibility becomes.

Pollution and Visibility Visibility is also a function of smoke and haze coming from industrial areas. Perhaps an airport is reporting reduced visibility, while the general weather conditions are good. The reduced visibility may not be cause for alarm, because it could be industrial air pollution drifting in from the city. A look at weather reports from other airports in the area that are not downwind of a city will show the real visibility trend. In the days before a lot of industrial pollution and automobile smaze were cleaned up, at New York’s La Guardia Airport with a light west wind, which basically said the weather ought to be good, the visibility could be one mile, while Newark airport, upwind from smoke-producing areas, had seven miles or more. This still plays out in some parts of the world, at times also instigating early and late-day haze—a possible hint to fog. An airport’s location can mean a lot. If Long Island, New York, has a northeast wind and there’s worry about fog and low ceilings, it’s a cinch that La Guardia Field, on the north shore, will have worse conditions than Kennedy on the south shore. The wind has to flow slightly down and over land to reach Kennedy, and this will help to raise the ceiling. Conversely, a south flow in the right conditions will clobber Kennedy, usually stopping about halfway up Queens, to the north, with La Guardia okay. What we’re saying, again, is that we must include the factor of terrain in our weather evaluation. If we are going to fly instruments into an airport, we can accept a forecast that calls for weather within legal limits for an instrument approach. However, these limits, again, are only legal verbiage, and because it’s legal doesn’t always mean you should go. Legal means regulations with fixed numbers like “200 feet,” but numbers cannot cover all the factors in weather flying. Wind and turbulence can affect an approach and may make a 300-foot ceiling seem awfully low. In an extreme example, you might have a legal 300-foot ceiling forecast for Daytona Beach, Florida, during a hurricane! You certainly wouldn’t want to go there. To some degree, these elements enter into all weather judgments. If it’s going to be necessary to descend through a thick layer of icing when a pilot’s experience and anti-ice equipment are limited, the pilot should not be interested in making an

approach, even if it is legal. There are a lot of commonsense factors in judging whether to fly or not, and legality shouldn’t always be the deciding one. It is folly to think that as long as there are legal minimums, everything is okay; there’s more to it than that! Of course, a pilot cannot operate below legal minimums unless ready to declare an emergency or pay fines; and maybe get hurt. There are other times when the legal minimums look too restrictive—for example, a low stratus condition with calm air and little wind. In such a situation, a person could probably cut a ceiling below legal minimums without much effort, but obviously, for reasons that go beyond weather, such is not smart. Generally, however, legal minimums are something not to go below, and there are times when one should remain above them, times when they are too low. Cheating on minimums isn’t clever. It’s well worth remembering that minimums are based on many things, and the important ones are terrain and obstructions under the descent path, to the sides of it, and in the missed approach area based mostly on things like airplane performance, radius of turn at an assumed speed, etc. Sneaking below minimums means we are taking the risk of hitting something. Speaking of not descending below minimums, of course we don’t do so unless we see, by the time we reach minimums, the actual legal airport environment. It is worth mentioning that aircraft with Primary Flight Displays (PFDs ) showing artificial terrain—synthetic vision—should never tempt us to cheat on minimums, and at the same time, we need make sure we do not get target fixation on these displays, slipping through minimums. Once below minimums, we’re visual, with any PFD reference only for primary flight data, which is just basic attitude, airspeed, altitude and heading, as well as navigation indications. These displays are amazing technology, but for whatever reasons, it is not approved, so we don’t do it.

How Do You Feel? Another serious factor in weather judgment—often overlooked—is how a pilot feels. Some days we feel good and very tigerish—we’ve had a good rest, our physical condition is tip-top, and we feel able. At other times we may be tired or have a cold that lowers our efficiency. We may be unhappy because of anything from a bad business situation to a fight with a spouse. It’s an honest fact that we aren’t the same every day—athletes aren’t, and they play, fight, or compete better on some days than others. It is difficult to stand off and objectively analyze how we feel. But some days you’ve got it, and some you don’t, and the ones you don’t should, under some conditions, raise your ceiling and visibility limitations. I (RNB) can remember an all-night flight from Kansas City to New York with stops at St. Louis, Indianapolis, Dayton, Columbus, Pittsburgh, and then Newark. It was back in DC-3 days, and the weather was bad, with an instrument approach

at each station down through an icy overcast to minimums. The flight was a heavy mail flight and at each station, we were delayed while they loaded and unloaded mail. I had a new copilot, too. Finally, 5 a.m. found me in Pittsburgh looking at Newark’s weather, which was forecast poor with precipitation. I turned to the agent, and told him the flight would hold for six hours and quickly added that it wasn’t that the weather was too bad, but only that I was exhausted and didn’t think it wise to fly any more bad weather without some rest. The airline, incidentally, never complained about it, and when I dropped by the chief pilot’s office a few days later to tell him what I’d done, he complimented me on the decision.

More about Wind We’ve looked at the forecast, the ceiling, visibility, precipitation, and at how we feel … what else ? Wind direction and velocity in relation to terrain, such as light winds flowing from bodies of water or strong winds flowing down nearby mountains. Some airports, snuggled beautifully against the side of a mountain, can be a tough place to land with high surface winds. Hidden in the winds can be the rotor from wave action downwind of the mountain, or even flow off low hills or ridges. It may be only a few hundred feet above the ground and have very nasty turbulence, plus areas of strong sink that will have you pouring on power while wrestling with the rough air. The trick is to be suspicious of such things close to mountains, or even those lower hills, and not be caught off guard. There are details, too, of runway alignment. Now and then we may be headed for a field with a single runway, where a crosswind will be too much to handle. This can catch us naked even with simple VFR flying. One day, flying a Piper Super Cub, when young and foolish, I (ROB) approached the old Evanston, Wyoming, airport’s single runway, thrashing in a strong and gusty west wind, only to find it dead across the runway. With the Super Cub’s short field ability, you rarely worried about runways, but this time I should have checked before launching over those long western distances. Thoughts of an across-runway landing were dashed by fencing either side. Fuel was tight but okay for a return downwind to Rock Springs, but I succumbed to destination fixation and landed. It wasn’t pretty, all was safe, but I was not proud of the decision to land. When I tried to leave in haste, having a commitment to be elsewhere, the airport owner made a great statement: “Well, if you really have to leave …” I left the next morning, the winds calm. High wind velocity is an indication of turbulence, made even more spicy and difficult when we are IFR on an instrument approach to low weather. Calm winds and approaches are delightful; they are easy approaches, but again, if we are on instruments, quite probably, because of the calm air, these approaches will be low ones with reduced visibility.

Speaking of airports, we should check NOTAMs for the destination. Has the snow been removed? Are the lights and facilities all working? What other things are affecting the airport’s condition?

Altimeter Setting Altimeter setting is reported on the weather sequences, and as we look at present and past reports, it’s a good thought to make a mental note of the pressure and see if it’s increasing, decreasing, or staying the same. We can catch a weather trend this way and, keeping in mind the pressure, we have a reference for altimeter setting in case we don’t hear one along the way. This is not recommended for IFR flying, for which an accurate altimeter setting is needed all the time, but the information is a little backup “just in case.”

Temperature and Dewpoint Again On those weather sequences, we find our old friends temperature and dew-point. We want to keep them in mind to relate to the present and forecast weather, and as a reference when watching the trend at our destination. It’s important to note, again, that time of day affects the value of temperature and dewpoint: sun coming up, they tend to separate; sun going down, they get closer with chances for fog; they come together when it starts to rain, too.

PIREPs Pilot reports are worth careful consideration, because another pilot reporting the height of the cloud tops, for example, is the next best thing to being there oneself. Like almost everything else, however, these reports must be absorbed with some thought about their validity. A report of the tops is a pretty definite thing, but reports of turbulence can be questionable. How turbulent is it, really? One pilot, being the nervous type, may yell severe turbulence, while old hard-nosed Joe says it’s just choppy. Notice, also, what kind of an airplane the report came from—one with a high wing loading, usually meaning bigger airplanes, wouldn’t be as troubled as a lighter airplane of the two- or four-place variety. So, what do we do if turbulence is reported? Look over the general situation and decide if there should be turbulence; if there should, and it’s reported, that’s that. If there shouldn’t be turbulence, and it’s reported nevertheless, then either a Nervous Nelly was flying the reporting airplane or something has started to move in the weather pattern that’s different from what’s forecast, and we’d better look things over again and decide what it might be. In either case, the turbulence report didn’t hurt and has only caused us to study things a little more and be prepared. As pilots, we should make an effort to report the weather we find, particularly cloud tops and bases, icing, turbulence, thunderstorms, or anything unusual. These

reports not only help pilots directly, but they help the meteorologist, which finally comes around again to better weather information, helping pilots and a lot of other people, too. Meteorologists have information on places that report weather, but they do not know what’s in between. Sometimes weather will cook up something they never knew about. A pilot has a chance to see these in-between places and realize that something different from the report may be happening. This is the time —an important time—to make a pilot report and to let the meteorologist know, too. A report that says, “Snow encountered between Albuquerque and Gallup,” may be an important clue that things are happening faster than expected, and the meteorologist should revise the forecast. It is important to remember that PIREPs only happen if pilots make them. We’ll need to make those calls to the FSSs, either on their specific frequencies in the area we are flying or on Flight Watch’s (EFAS) designated frequency— currently 122.0, if we are flying below 18,000 feet, or on the airport’s appropriate controlling frequency if an airport-area event. If we don’t have time to make a PIREP in flight, say from a cockpit workload situation, and on the ground we feel the information still timely, we can call the FSS phone number of 1-800WXBRIEF and make the report. PIREPs reporting conditions such as wind shear, breaking action, ice on an approach are extremely important and possibly of immediate safety benefit to other aircraft. We’ll bring this up again in related chapters.

On the Ground, Too Report the braking action you find on landing when ice, snow, water, or whatever make stopping an adventure. While a larger airport may offer braking action reports, unless they come from a friction-measuring vehicle, it is pretty subjective, the opinion of a person tearing down the airport’s runway and then slamming on the brakes. Pilot braking action reports are also subjective, but at least they are from an aircraft, with the pilot understanding what is needed in the real environment. At smaller or less-frequented airports, these reports are often the only information available, so your braking action report is important. Remember the opposite, too, and request past pilot braking reports for your own information before landing on questionable winter days and nights or at times when the runway is covered with water, perhaps the result of a thunderstorm or prolonged heavy rain. The control tower may not always give a braking action report. When they get busy, things can get lost in the heat of battle. Once, while checking out a new copilot in a 727, her first jet transport checkout, the temperatures had fallen to around freezing after recent precipitation. A few miles out on final approach, with no braking reports from the tower, we just had “that feeling,” so asked. The tower returned with a braking friction number, necessitating flailing of pages in that homemade, special little binder of

important references we all should carry. The reading translated to poor, and confirming with the tower, we were told they just give the numbers and it’s up to us! In other words, they had no clue it was poor braking and should be advising aircraft. We also had a slight bit of crosswind. Although skilled with many levels of flying experience, the copilot had learned to fly in her father’s two-place, tailwheeled Globe Swift, which meant she’d had a great flying background, including using the rudder. Her inquisitive look, towards pointers on how best to handle it in a 727, inspired an easy response: “Just land it like you would your Dad’s Swift in a crosswind.” She aced it.

Summing Up For the terminal (an old term for an airport), we study forecasts for past, present, and future; we read old and current METARs and check them against the forecasts to see how the forecasters have been performing. We look at other terminals within a couple of hundred miles of our destination and relate them to our destination weather, and most importantly, we study reports and forecasts of airports beyond our destination from which weather might come. If, for example, we are westbound and a front is approaching the field for which we’re headed, we check how the front has been acting as it approaches. Say we’re going from Columbus, Ohio, to St. Louis; in addition to St. Louis, it’s important that we study Kansas City and Springfield, Missouri; Oklahoma City; Burlington, Iowa, and a station or two west of there, such as Omaha. A wide sweeping glance will tell us where the action is, and then we relate it to St. Louis. We need an alternate for our destination airport, even when flying VFR and especially MVFR. We study alternates as thoroughly as we do the destination, and perhaps add a few factors. One is that we want the alternate to be as good and have as little chance of going bad as possible. While we may head for a destination that has a nervous forecast, we want an alternate that has a solid one, and we don’t like alternates that do not have a solid forecast. In tune with this, we should always have, tucked back in our mind, which direction to go for an “out”—a diversion toward improving weather, the safest weather area. This is important for all flying, but especially VFR. Legal alternate minimums are fairly low, and it is possible to have an alternate that is forecast to be above alternate limits for arrival and below them an hour later. This brings about such statements from pilots as, “That’s the paper alternate, but my real out is ____.” They want something that’s definitely going to be good, like an airport that is behind a front and on the uptrend or one that will not be influenced by the destination weather, like Montreal when the New York area has a low moving off the coast. Long Beach, California, may be a legitimate alternate for Los Angeles, but a knowing pilot says that Palmdale is the solid-gold out when those low clouds from the sea start to roll in, or Newark is no good for JFK, as

one thunderstorm can kill the whole New York area. It’s wise to consider that the FARs give numbers to go by, but because weather isn’t a precise, number-specific phenomenon, one often needs extra protection above and beyond the FARs. Paradoxically, or hypocritically, the FARs are often too restrictive and hold us back when it isn’t necessary. However, this is the outcome of interplay between the need for definite rules in the book, and the fact that so much of flying and weather depends on judgment. Judgment is difficult to cover in regulations. I’m glad I don’t have to write them. It’s worth noting, before we leave the thought of terminal, or airport, weather and the ways of looking it over, that we always relate our weather study back to the basics: big picture, time of day and season, temperature change, moisture change, terrain, wind, forecast, and the almighty “IF.”

7 Checking Weather for the Route After considering the destination and deciding it’s good enough, we have to learn what’s in between: the en route weather. What bothers us en route? If we’re VFR, it’s cut and dried: we must have enough ceiling and visibility to stay VFR, and the more mountainous the terrain, the more ceiling and visibility we need. We can fly on top of clouds, but they really should be no more than scattered and very clearly and confidently forecast to stay that way! On instruments, our concerns are ice and thunderstorms, cloud tops, bases, and ceiling underneath, especially if we’re single-engine and want some degree of tranquility regarding the possibility of engine failure. Turbulence is a factor, but is generally related to thunderstorms or mountain issues. Wondering about ice and thunderstorms, the important question is: Are we dealing with them in fronts or only air-mass conditions? This knowledge is very important, because with airmass thunderstorms, your chances of steering around them are good; for ice, you probably can get on top, unless the tops are too high over mountains. Through fronts, however, the thunderstorms will appear as a solid line that’s impenetrable, and ice will be between you and the other side of the front, with strong probabilities of confrontation. VFR or IFR, of course, we want to know about winds—head or tail and how strong. More of all this as we go along. The big picture has its usual importance, and we want to take note of the weather system that may move onto or off the route. The method of looking over en route weather is much the same as for the terminals: we want the same scrutiny of forecasts for before, now, when we get there, and after. We mix in the same factors and emphasize terrain, because it intensifies any bad weather that may lie along the flight path.

Weather Is Mostly Good We talk a lot about bad weather and may put a gloomy look on everything, but we’d like to make two points. One is that if we only talked about clear weather, there wouldn’t be much to talk about. The other is that most of the time, thank heaven, the weather is good. We fly in clear skies more than we do in annoying cloudy ones. We may have cloud cover due to postfrontal conditions, but it is easy to top and fly above. Fronts along the route, with their associated low-pressure areas, are the things

that can make it tough. In these areas, we find the difficult weather, the ice or thunderstorms, thick cloud decks, precipitation, high-speed winds, and turbulence. But this kind of weather covers our routes only a small percentage of the time. I (RNB) spent four and a half years in weather research, trying to find bad weather. I sat on the ground many, many more hours waiting for bad weather than I have ever sat as a pilot waiting for good weather. Often, too, the bad weather that was supposed to be out there wasn’t, and instead of ice or snow, I’d find myself flying disappointingly on top, looking at blue sky or stars. All this is simply to say that things are good more than they are bad, but we have to talk most about the bad. Clouds rarely start at 200 feet and go up in a solid mass to 30,000 feet or so. We can draw a mental vertical section of how clouds are stacked. They are usually in layers that become more complicated, and the spaces between them fewer, the closer we get to a low or front. In their simplest form, we may have a single stratus deck behind a cold front, one layer with a reasonably reachable top, or one layer where warm air is overrunning cold ahead of a warm front—a cirrostratus deck, for example—with a high base and nothing below. Then, closer to the warm front, we find an altostratus layer with a lower base. Closer in still, this lowers further and rain starts, whereupon a low stratus deck forms, adding another layer. At the front, the layers merge.

Something on Fronts A cold front has much the same profile, but its area is smaller. The distance from front to back is shorter, and it does not take long to fly through the front. A cold front can, however, be more violent than a warm front. Warm fronts are slow— and sometimes tormenting—while a cold front is a quick punch in the nose. As we know from primary meteorological study and from picture-book drawings, fronts come out of a low-pressure system. The warm front is a long arm sloping out ahead of the low, and the cold front is another arm pointed down, southward, from the low. The farther away from the low we are located on a front, the less violent the weather, and the closer we are to the low, the tougher the weather.

Occlusions and Zippers A type of front we haven’t talked about is the occluded front. I (RNB) remember when I was a very youthful copilot who hung around the weather office on my days off, and I asked the meteorologist what an occlusion was. He said, simply, “It’s just like closing a zipper.” This really didn’t tell me much, until I learned more and found that his explanation was quite exact. At the center of a low, the warm and cold fronts meet. When, near the center, they get together and one

catches up with the other, they form one front. This process of catching up progresses downward from the low center. It’s as though a zipper pull handle were at the low center, with one side of the open zipper the cold front and the other the warm front; the zipper closes—pulls—southward as the cold and warm fronts come together and become an occluded front. What does it all mean? Generally, it means the low is beginning to fill up and weaken, with cloud bases getting higher and tops lower, until the low is finally a trough with little weather. But in the early stages of an occlusion, things can be rough and tough, with the characteristics of a cold or warm front, depending on whether the cold air is catching up to the warm front and lifting it upward as a cold front or riding up the warmer air ahead to give it the qualities of a warm front. Sometimes the “closed zipper” portion of the occluded front tips and bends over backward. It is then called a “bent-back occlusion” and will act like an additional cold front. Because of the counterclockwise circulation about the low, such an occlusion is fed moisture and can cause some mighty mean weather. With the low near a coastline, a massive amount of moisture is fed back over the top of the low behind the occlusion. The low may move slowly, or not at all, and just sit there spinning around, moving that moisture back around it. Such a low, stalled over the Gulf of Maine off the New England coast, can bring massive snowfalls and foul weather for days. Generally, we think of an occlusion as “occluding out,” which means that the low is starting to fill and die. Like everything in weather, however, you cannot always count on this, and while an occluding low generally spells gradual improvement, it can, on occasion, regenerate itself and create more bad weather. It’s necessary to keep a close eye on occlusions. Visualize from where an occlusion may continue to have a moisture source to feed into it as a hint to what may happen. If it’s in the dry part of the country, and a big moisture source is not available, then the low will fill and things will get better. But near an ocean or gulf, watch out!

Large-Area Weather Some frontal conditions can be very widespread, causing weather to cover a large area. We find this most often in winter, in big lows having large areas of overrunning warm air in their northeast sector. In winter, these can cause large areas of freezing rain. Usually this type of storm is not difficult to spot or predict, and the Weather Service will have it sufficiently well analyzed to make an accurate forecast, but that doesn’t relieve our task of keeping a skeptical eye on it. As far as flying into such an area is concerned, we shouldn’t; it’s better to consider the coziness of a fireplace and a good book, unless we’re experienced, well equipped, and have lots of fuel.

The Important Northeast Corner As we study weather systems, it’s important to visualize where the weather is. In a low, most of it is ahead of the system, in the northeast corner (in the northern hemisphere). This is ahead of and in the warm front. If we were to cross a system starting in the east-northeast and fly southwest, we’d first fly under high clouds, then into an area of rain or snow or possibly freezing rain, and then through an area of heavy precipitation, ice, and thunderstorms. This is the warm frontal surface. Then we would break out in a relatively clear area with a deck of cumulus or stratus or even clear skies. This is the warm sector. Incidentally, a low will generally move in the direction in which the isobars are oriented in the warm sector. Past the warm sector, we’d bump into the cold front: a narrow band of thunderstorms or ice, with lots of clouds and turbulence, but a fairly quick passage. Immediately behind a strong cold front there is a clear area, and we may think all is over, but as the cold air builds in, a stratocumulus deck will develop, and in winter probably will become a solid overcast with fairly high tops and lots of ice in the clouds. But as we fly farther from the front, this cloud mass begins to show breaks, then becomes broken and gradually scattered, with the tops lowering, and finally there will be clear skies. How fast all this occurs depends on our distance from the low’s center. The interesting part of the system, however, is that northeast portion. In this area are the easterly surface winds that cause fog and low clouds. Toward the front, precipitation begins, causing low clouds, and wide areas of poor visibility and ceiling. In winter, rain aloft will fall into cold air and create freezing rain and ice storms. This is also the area of heavy snowfall. This area may often be extensive enough to make finding an alternate airport difficult; it can also take a long time to move off. Although we cannot forget the cold front, the big action is up there ahead of the warm front, and this can be true hundreds of miles away from the low, as well as near it. In Dr. Horace R. Byer’s book, Synoptic and Aeronautical Meteorology , he says, very accurately, “The warm front situation may properly be regarded as the most serious hazard to aviation …”

A weather system—the big picture. Note all the clouds and problems in the northeast sector. Thinking of this picture and then relating it to your location in an actual weather situation can tell you what weather to expect and which way to go. It’s a picture that deserves a lot of study and mulling over. (Note the jet stream, which would be up high, near the tropopause.) (NOAA PHOTO) That’s a good statement, because a warm front has it all, and it’s not simply the frontal surface itself, but also the big area northeast of it that requires study and respect when we look over the weather. While studying the warm front and the NE sector, it’s a good idea to visualize being in various parts of this and which way we’d retreat toward better weather. The warm sector, south of the warm front, generally has the better weather, though we should watch that area for the eventual arrival of a cold front from the west. Running away toward the NE demands care to be certain the weather isn’t running with us and preventing our escape from the lowering ceilings, visibilities, thunderstorms, and increasing precipitation. Warm fronts slope, in a shallow way, from 100 to 300 to 1. So, if the frontal surface—the place where surface reports show wind shifting from easterly to southerly—is at, say, Amarillo, Texas, a pilot will find the warm front aloft anywhere from 100 to 300 miles northeast of Amarillo. That would be the altitude

where warm front thunderstorms begin, or how high we’d have to climb for above-freezing temperatures when there’s freezing rain down low and we want out of it. This warm front slope is worth mulling over at leisure and important to note when checking weather.

Drawing of a low taken from an actual weather map. Note the mass of clouds on the northeast and north side, extending far west. Also note the east wind covering that entire area, bringing in the messy weather. Be wind conscious; where it comes from and what that source region is like and what weather it may breed.

Go the Short Way From studying weather, we tend to get the idea that we are always flying through fronts at right angles. Of course this isn’t the case; sometimes our course is along a front, or at any angle to it, in which case tough weather can be prolonged. So there are times when it’s wise to detour a bit and take on a front at right angles rather than slugging it out for a long period along the front.

The analysis of weather in lows and fronts tells what we may have to contend with en route; this is what we are looking for when we study the big picture. Checking the en route weather, the VFR pilot decides if the ceilings and visibilities are high enough to fly safely under clouds. If the decision says they are, then the question is, will they stay that way? The pilot wants to know if any system is moving in that will make the en route weather deteriorate. If there is approaching weather, but the pilot thinks there is time to complete the flight before it reduces the ceilings and visibilities below a workable limit, then the pilot must decide which way to run and what to do if the deterioration occurs ahead of schedule, with visibilities going down and the ceiling forcing the airplane lower and lower. We must remember, and it’s very important, that the timing of forecasts is not always exact; they cannot hit precisely the moment when a front will pass, or a place fog in or clear, or any other weather will occur. The state of the art is not such that weather can be forecast all the time with absolute accuracy. That’s why we must know weather and watch its movements all the time. We may repeat this theme many times, because it is so important. We may be puzzled by weather’s changes, but we should never be surprised or caught off balance! The instrument pilot looks at the weather en route differently. She or he can accept weather that has ceilings and visibilities well below those necessary for safe contact flying. The question is, how tough will any turbulence, ice, or thunderstorms be in relation to the equipment and pilot ability?

It Takes Time to Know It would be easy to say that if pilots are going to fly instruments, they should know how to fly instruments extremely well and should have all the equipment; but this isn’t very realistic. Even an FAA-rated instrument pilot has to go through a learning period. The rating, though earned after a lot of hard work, is only a beginning. The FAA says, in effect, that rated pilots, new or old hand, may take off, go immediately on instruments, stay on instruments, fight ice and thunderstorms, shoot a 200-foot ceiling in heavy rain at the other end, miss the approach, pull up on instruments, and go to an alternate and make an approach there. That’s a pretty exciting day’s work for the newly rated pilot, especially flying without a copilot, maybe no autopilot, while also busy getting ATC clearances and tuning radios, or the busy workload of constant function for electronic instrumentation. It’s obvious that the less experienced pilot doesn’t want to fight all that (sometimes the experienced one doesn’t either); so what does the new pilot do? Learn to crawl, then walk, and finally run; that is, take on weather a little bit at a time, gaining experience with each flight. This comes up again in the chapters discussing instrumentation and flying proficiency.

Seeing a weather map is an important part of studying en route weather, but at times, a map isn’t available. Then we must get all our information from forecasts. Either way, maps or not, a lot of the weather comes from TAFs, METARs, and other products, so we must learn to read, hear and put together a picture from that time-proven coded data. If we get our weather from the FSS we see example of a proper, systematic briefing, which is what we should replicate if we get the briefing ourselves from computers or personal electronic devices. First, their briefing starts with a synopsis, which demonstrates that the Weather Service and FSS also like to begin as we do—looking at the big picture. Then they go on to tell cloud bases and tops, where icing, thunderstorms, and turbulence will be, and what the outlook is for the next weather period. The forecasts come next, and we listen to them carefully, trying to visualize where all this weather that’s going on. We try to make a dull bunch of words and symbols come alive and paint a picture. It may say “–22020G30KTS 3/4SM SN VV012, TEMPO 1/2SM SW OVC003,” which doesn’t seem to make much of a picture; but it can if we concentrate. The ceiling is going to be indefinite, 1,200 feet, which isn’t bad; but threequarters of a mile visibility gives a gloomy sight of flying in severely reduced visibility. We’ll see only straight down and very little ahead, especially in snow. The ground will be snow-covered and all look much the same; navigation will be difficult. If the terrain is hilly with mountains nearby, we’ll have to be extra careful. It’s not a VFR operation. The report continues to say that the ceiling occasionally (temporarily) will be 300 feet, ½-mile visibility in snow showers. We picture sudden deterioration in conditions, as the wind picks up and heavier snow showers come in gusts. Your skeptical nature tells you that the visibility will not be ½ mile from the cockpit, but more like ¼ mile. We know it will require an instrument approach to the runway, but possibly those snow showers will take it below minimums. Probably one of the most important points in these TAF forecasts is the probability outlook stated, for example, as PROB40 0407—which means there’s a 40 percent probability between 04 hours and 07 hours that something will be better or worse, the “something” being indicated by the coded letters for the weather condition. The TAF might also say, “BECMG 0407 _” [Becoming between 04:00 and 07:00]. What it will become will be expressed in the code; FG for FOG, SKC for SKY CLEAR, and so forth. What the coded expression PROB40 really tells us is that there is some question as to the preciseness of the forecast, that there’s some doubt, which is a signal for us to be extra wary and to watch and keep up with the weather’s action. The statement “BECMG 0407” means that between 04:00 and 07:00, things will change for better or worse. It’s our job to see how that prognostication is playing out; if it’s supposed to become better in that time period, it’s our task to

watch and see that it does, which means the old business of getting the en route weather reports each hour and writing them down in order to compare the latest with earlier ones to learn which way things are going. If we are fortunate to have airborne data link weather, it’s easy to call up these needed reports, but if not, don’t be bashful about asking by radio for the latest forecast or any supplemental ones that may have been issued. Important in our en route flight are the winds aloft. First, of course, we study them to find their direction and velocity for flight-planning purposes, so that we know how long the flight will take and how much fuel we’ll need. Add 20 percent to headwind velocities and take away 20 percent from tailwinds as a “fudge factor.” That’s about as accurately as they are forecast on an average. The winds should be studied at various altitudes. We are generally accustomed to the idea that the winds are stronger the higher we go, but this is not always the case; sometimes we find lower velocities up higher, which could help if we are flying into a headwind. We study the wind at various levels in order to choose the best altitude at which to fly. An old rule used in DC-3 days when flying into headwinds was to fly high in southwest winds and low in northwest to reduce the wind effect. It’s not always true, but it’s not far off. Although the DC-3 is past, the weather at those altitudes isn’t, and that’s where a lot of general aviation still flies, often at similar speeds. Wind is really a secondary factor in selecting altitudes; weather is first. We wouldn’t want to fly in a deck of icing clouds merely in order to have a better tailwind or less headwind. So weather is really the first factor in picking an altitude (besides terrain clearance, of course, which comes before everything), and wind is second. Airplane performance is another factor. We want to cruise as close to the airplane’s optimum cruise altitude as possible; weather and wind will dictate whether we can or not. It’s good to keep in mind the wind at other levels, in case ATC sends you to a different altitude than the one you want. The trip might take longer at a different level. How will this affect fuel reserves? In a jet, this could be quite serious, but it’s also important in a 100-horsepower light plane. The winds aloft also give weather clues. Suppose the wind for the trip was forecast southwest, but as you fly, you find the wind really coming from the southeast. That’s a clue that the weather may be starting to do something different than what was forecast, and it’s time, again, to watch developments more carefully. Especially in the eastern half of the United States, pay special attention when the wind works toward east for generally deteriorating weather changes. Another wag is that if we’re in post–cold frontal conditions and the winds are forecast west to northwest winds, but they swing southwest, a little post-frontal trough may be brewing, maybe kicking up a line of showers. A last important point about studying en route weather regards deviating around weather. We should not look only at the weather on the direct line between

where we are and where we want to go. The old idea that the shortest distance between two points is a straight line doesn’t always apply in flying. We should look well to either side of our route and see what’s going on. Sometimes we can circumnavigate bad weather. Sometimes making an end run is worth it just to get better winds, because we are not interested in how far we fly in an airplane, but how long it takes. Going “off course” to get better winds may actually make the flight shorter. This is especially true for long flights. If we’re flying from the Midwest to California in winter, it’s generally better to go via El Paso than via Denver; the mountains are lower, the weather less violent. Even short flights sometimes can be flown in better weather by a small course deviation. As we said before, it pays, in studying en route weather, not only to look on course, but on both sides, too. This applies particularly when there are thunderstorms rumbling about. The radar summary maps show the basic areas of thunderstorms, while NEXRAD, both on the ground and in the air, gives us tight data of these areas—a real heads-up. We can often go around the entire mess, which usually means less distance and time compared with coming up to weather then having to make a big cut around it; sometimes this latter path is too close and too intense for slower aircraft to escape without being engulfed by the weather! However, we again repeat that the radar maps and NEXRAD are not for use to wiggle through a thunderstorm area; that’s a job for airborne weather radar.

Why and If Forecasts and synopses aren’t enough; we need to know what the weather people are thinking deep down inside behind the official stuff that comes from the computer. We should talk to a meteorologist if the weather setup is dicey, which was why we used to go to, or at least call, an NWS station where real meteorologists live or, if you are subscribing to it, one of the special weather service companies that have meteorological staff. Again, there are NWS offices that will accommodate questions; they just are somewhat challenging to find. The reason we want to get this analysis is to know what the forecaster’s confidence really is. What is the chance of the forecast working out as advertised? Is the forecaster 100 percent sure? Fifty percent? It’s important for us to know. Getting a clue to their thinking not only tells us how cautious to be, but it also gives us a chance to ask “why” questions. If the ceiling is going lower, “why” is it? If the answer is because of an approaching front, then “why” is it approaching? That might result in us being told about a low-pressure system on the move, and then we ask “why” is it moving this way, how fast? The answer might be that a high-pressure area is blocking it from moving in another direction. And we could ask “why” is the high

blocking and not moving? If we ask enough “whys,” we can finally get a feel for how solid the facts are on which the forecast is based and thus how much confidence we want to put in it. Asking “why” is a wonderful way to do this, and a great way to learn more about meteorology, too. Unfortunately, we usually don’t have a meteorologist to talk with and have to rely on the published forecast percentages we spoke of before. If there isn’t any way to ask the “why” questions, we can ask them of ourselves and try to figure out the answers as a good way of evaluating what may or may not occur. This, of course, really outlines the task—both knowledge and ability—for those seeking weather electronically, all by themselves. After “why” comes “if.” As we absorb the forecasts, the big picture should form a background in our mind into which we fit the forecast, and while doing this, we develop our “if” thoughts. “If” thinking is very important, as we say to ourselves what “if” the front slows down, what “if” it speeds up, what “if” the wind stays east, what will it be like and what’s the effect on me “if” the forecast does a 180-degree flip? And we ask ourselves, “if” it does something unexpected, what will I do in flight? Being “if” conscious keeps surprises out of our lives and has us prepared for something worse that might come along. A simple example is a cold front in eastern Ohio. We might be flying from Bridgeport, Connecticut, to Harrisburg, Pennsylvania. The forecast says Harrisburg will have scattered clouds, visibility five miles in haze, and southwest wind. It will stay that way until 17:00, when the scattered will become broken with a risk of thunderstorms. The forecast for later shows thunderstorms and a frontal passage. It’s no problem for us, because we are going to arrive there by 14:00, long before the thunderstorms. But our “if-mind” says, “Keep an eye on it.” The front is out there and moving; a prefrontal line squall could pop out ahead of the front. We would do well to get the latest weather before leaving Bridgeport and current weather as we fly en route. All this example does is demonstrate the kind of thinking a weather-wise pilot does, especially in relation to that synoptic picture. In this simple case, it’s obvious the forecaster based the terminal estimate on the movement of the cold front. It looks as though it will move, but will it move at the rate expected? Best information says it will, but as we know, they cannot hit frontal movement on the nose. The forecaster planned for that a little in the report when warning of a risk of thunderstorms for 17:00 in case things moved faster than expected. In the same weather conditions as above, if we were coming from Dayton, Ohio, to Pittsburgh, we might be expecting Pittsburgh to be in good weather behind the front, but if the front slowed down, Pittsburgh would not clear out, and the front could still be in the area for our arrival. It’s all part of the necessary

suspicion, the constant knowledge that weather forecasts do go sour. So when we look at the weather, we keep in mind several key points: big picture, time of day and season, temperature-change possibilities, moisturechange possibilities, terrain, wind, forecasts, and the big what if!

Don’t Fear Weather … All the emphasis we’ve put on weather so far may make it sound as though the sky, most of the time, is full of fearsome conditions. Well this isn’t so, and even when bad weather prevails, respect, not fear, should be the attitude. Weather makes flying interesting, even though it frustrates us at times. But if we fear it, our flying will be affected; we will not perform as well as we can, and emotions may overcome judgment. It is fun, more often than not, to fly in bad weather. It makes us feel a part of nature again and not a coddled creature living only in soft comforts; it builds our confidence. The point is that to handle weather we must know, again and again, that it is capricious and its movements unreliable. What we are trying to do is make certain that we outguess this uncertainty and when we cannot do that, be prepared to handle it. If we prepare by obtaining weather information before flight, keep up with it in flight, and have alternate action always available, then we have respected weather and can handle it. But if we do not do these things, we may well find ourselves in an alarming position, scared of everything around us and not thinking clearly—a recipe for disaster!

… Or Worry about It Worrying about weather shouldn’t upset our lives, and it doesn’t help to fuss in advance over what it’s going to be like when we fly. In my youth, I fretted about weather days ahead of a cross-country flight: Would there be ice? Thunderstorms? Low ceilings? Using a little extra imagination, it was easy to get all upset. But somewhere along the way, I realized that there wasn’t any way I could confront that weather until the day came to fly it, so there wasn’t any point in stewing about it in advance. It’s good practice, of course, to check weather daily, in moderate fashion, to keep the trend—the rhythm—in hand, but the time to get steely-eyed serious is when first walking into the briefing office (sadly rare these days), sitting down with a computer or personal electronic device focused on a good, thorough briefing, or picking up the telephone to obtain the information. Then, with a good briefing and thoughtful preparation as to fuel, alternates, and how to approach what is out there, we can deal with the conditions in a relaxed and unworried mood. But worry the night before? Never! That’s the time to get some sleep and be ready for what comes on the morrow.

8 Equipment Needs for Weather Flying It is almost impossible to talk about flying weather without discussing the equipment of both the airplane and pilot. The airplane we fly must fulfill certain requirements, not only of instruments and radio, but also of power and range to battle the elements when necessary. This doesn’t mean it has to be a big fourengine transport, or even a small two-engine one, but the airplane should have a decent rate of climb, and more importantly, it must have enough range for the flight, from takeoff to destination, against a strong headwind and along the wiggling course that may be necessary because of ATC. There is an impressive difference between the straight-line distance between two places and the distance measured over the wandering routes of the Federal Airways System.

It’s Farther Than You Think While the shortest distance between two points is a straight line, airplanes, flying IFR routes over the airways, don’t always fly that way. One route we often flew was a 251-mile direct flight from Van Sant airport, a small field in eastern Pennsylvania, to Montpelier, Vermont. If we filed instruments, however, the airways distance was 304 miles, more than 50 extra miles, and in a 172 Skyhawk that’s a lot. Another flight made around the New York area was 60 percent longer by an ATC-cleared route, which avoided the New York airport area, than over a directly filed route. These extra distances take lots of additional fuel and that affects safety. Suppose we were trying to beat darkness and approaching weather—a slightly stupid combination—and then found our ATC clearance was via a modified route that would take 70 minutes longer, not counting possible headwinds. We could easily run low on fuel, fly into darkness, and meet bad weather head on. To plan ahead for this possibility, we can check the many preferred routings—“canned routes” developed by the FAA/ATC folks—not only between defined city pairs but we can also link into these routes from smaller airports near the main pairing ones. We can find data on these routes before departing, either online, from ATC, or by contacting an FSS, as well as publications such as the Airport/Facility Directory. In considering our aircraft’s range, we should also include enough fuel for reasonable holding at the destination and then diversion to an alternate airport against a headwind. Although this holding fuel is not required for noncommercial

aviation, it is a good idea, considering the myriad of surprises we can encounter, from weather to an aircraft with a blown tire blocking a single runway. Furthermore, of course, some fuel should remain in the tanks when arriving over the alternate, legally enough for 45 minutes at cruise speed, but more is not a sin. In summary, this is the needed range: 1. 2. 3. 4.

Departure to destination, (considering wind and weather), plus Holding fuel, plus Fuel to alternate (again, winds, weather, and normal cruise speeds), plus Reserve over the alternate Let’s break these down further. Departure to Destination: Departure to destination, the long way. It is most important to know the en route time, with winds, weather, and normal cruise speed taken into consideration. If we are going through bad weather, the wind may be strong, and we may need to deviate around challenging weather situations. Slugging against the winds of an active low-pressure area may give ground speeds low enough to cause apprehension. We need fuel for departure and arrival wanderings as directed by ATC. You do not simply fly to the destination’s approach point, make an instrument approach, and land. If it’s a busy terminal you may be told to fly vectors that add many miles to the distance already flown over the wandering airways. One route into JFK from the north has an average vector distance of 91 miles! If we’re flying a jet, and doing it at a low altitude to which we may have been cleared, those 91 miles can use up a lot of fuel and make our reserve a considerably nervous, lower amount than we’d like to have. Sometimes, in the vicinity of coastal or lakeside cities, these vectors can also carry us over big areas of water—something to consider in a single engine aircraft. (This makes life vests as regular equipment a worthy thought; they don’t take up much room and weigh little.) During climb, fuel consumption is higher and speed lower, so the altitude to be flown will affect the total fuel needed. This can be determined with knowledge of the average rate of climb, the average true airspeed during climb, and the fuel consumption at climb power. Today, new aircraft manuals provide more complete performance information, such as better climb data, but many of us still fly older equipment. As a ready reference in flight planning, a pilot can make a handy, small chart that will give the fuel burned and the miles made good by the airplane in climbing to various altitudes, as well as for cruise and descent. The one we made is in two places: one in our flight kit for flight planning and the other stuck on the side of our airplane’s headliner, in the pilot’s view, along with the checklist.

Weather uses fuel. For example, in icing conditions, the airplane can lose speed, and because of extra power and/or carburetor heat, the fuel consumption will go up. Wandering around thunderstorms also adds miles and consumes additional fuel. It is difficult to say with precision how much to add for ice or detours around thunderstorms, and pilot judgment must prevail. But awareness of the fact that these things take fuel is a good beginning, and a 10 percent cushion will serve as a start. Holding Fuel: Again, it is difficult to judge how much we need, but there are factors to help us make an educated guess. First, is our destination a busy terminal? If so, the delays can be long. Obviously, if we are going to Chicago’s O’Hare, the delay will be longer than for Reading, Pennsylvania. Time of arrival may also affect holding time. Any big terminal will have much longer delays during their busy times; say, early morning, a midday push, or between 4 and 8 p.m., rather than at midnight. Holding ability also depends on the airplane. A piston-engine airplane’s fuel consumption can be quite miserly when just lolling about at low altitude. A jet, however, uses lots of fuel, and is especially critical at low altitudes. If jets can hold above 20,000 feet, their fuel consumption can be brought within reasonable limits. However, the modern higher-bypass jet engines are less greedy than straight jets, especially at low altitude, but still not like a piston engine or some turboprops. The weather forecast enters into the holding problem. A person doesn’t want to hold, for example, while waiting for the arrival of a cold front. If ATC says the hold will be for an hour, with a cold front due within that hour, and reports indicate that the forecast is accurate, it may be wise to proceed immediately to the alternate and forget about holding. If it is late and fog has formed, there is no point whatever in sticking around. This, again, emphasizes the importance of keeping up with a range of weather reports in flight. As a yardstick for the minimum holding fuel, there should be enough for 1½ hours at a busy terminal and 30 minutes at more out-of-the-way places. Traffic can back up badly at a busy terminal or alternate because of thunderstorms, or even just wind changes necessitating “turning the airport around,” as the saying goes when changing runways, during which landings may cease entirely. Traffic keeps pouring into the area, and stacks up even worse than in winter conditions. We’ve seen busy airports go from 15-minute delays to those approaching two-hours in a matter of minutes, because a thunderstorm hit the field: it had number one priority! Fuel to Alternate: Fuel to alternate is just like fuel to destination and should include the same factors, that is, total “long” distance routing, wind, and weather en route. As mentioned elsewhere, watch out for alternates too near the destination, potentially messed up with the same weather problems.

Fuel consumption can be computed on a long-range-cruise basis to save fuel, but that’s shaving hairs unless we absolutely need to, so if possible, we should use normal cruise. Concerning long-range-cruise, it’s surprising how it will save fuel, especially with larger aircraft, even into a fairly strong headwind, but it may not save much at all in very strong headwinds. A little study using a computer and an airplane manual—at a leisure time—will show this. Speaking of headwinds, they affect airplanes according to their true airspeeds. A 50-knot headwind against the no longer operational, but magnificent, supersonic Concorde was about 3 percent, or something like six minutes extra time on a Paris–New York flight of 3,200 nautical miles. But 50 knots on the nose of a Cessna 172 is 45 percent, which means an hour and nine minutes extra between New York and Washington, about 175 nautical miles. It’s important to explore headwind and tailwind numbers in order to know what they do to range and fuel, on our individual airplanes, at normal and long-range airspeeds at different altitudes. With this knowledge, we can quickly set up for maximum range when we really need it. Reserve over the Alternate: Reserve over the alternate depends on the weather at the alternate. If it’s clear and forecast to stay that way, the reserve can be minimal. If the alternate isn’t clear and instrument approaches are required, even with a fairly high ceiling of 1,500 feet or so, more fuel is needed, because there may also be traffic delays at the alternate. Often, when an airport closes down or becomes unusable, everyone holding at that airport flies off to the same alternate. This moves the congestion from one airport to another, and the alternate can be a madhouse of delay and confusion. Arriving over the alternate with minimum fuel in this situation is a scary proposition. Sometimes weather stays bad far beyond when it was forecast to improve. This can require creative changes to the whole game plan, which can work well and timely if we are checking weather along our flight’s route, far in advance of intended arrival time. One morning, I (ROB) was heading for Seattle and early fog hung around three hours later than forecast, producing below minimums visibility. Although I was flying a 727, the scenario could apply to any aircraft, general aviation or otherwise. The forecast had allowed one of those “paper” alternates of Boeing field, literally down the road, it too still fogged in, as it was from below Portland, Oregon, to Canada. Holding started east of the Cascade Mountains, which was good, as we were not thrilled with the idea of holding over the coast, then, if nothing improved, having to make a fuel-sucking climb back over the mountains. Pasco, Washington, was a safe alternate and lay below in clear skies. Finally ATC said things had lifted to minimums and an aircraft with similar minimums to ours, (which was important, as some aircraft with Category III ability had been making approaches and landings), would try the approach. We cautiously headed west in

kind of a straight line hold, slow and up high saving fuel. That airplane missed the approach, so realizing it would become an iffy situation, with more holding and plenty of aircraft ahead of us, we turned around and dove into Pasco, quickly fueled, then reappeared in Seattle about an hour and change later. Had the aircraft ahead of us made it in or diverted? You know, we really didn’t care, because our decision was safe, with good cushion. Generally, when one decides on making a diversion to an alternate, it’s often best to stick to that decision, even if tempted by suddenly improving weather at the original destination. Unless we have gobs of fuel, or the clearing weather is dramatic and bulletproof, we can easily find ourselves stuck in the middle, with no airport reachable; one due to bad weather, the other from lack of fuel to reach it. Sometimes it’s hard, with ATC telling us the weather has just improved and we can probably make it in, but we may find it best to forget that original destination even exists. As we begin weather flying, of course, we should pick alternates that are clear and definitely forecast to stay that way. When we say “clear,” we mean broken clouds or better and ceiling 2,000 feet above the highest terrain within 50 miles. With experience, as well as thinking far ahead during our flying, we’ll begin picking up on things that will have us making good decisions way before it’s time to do so. It is most important to develop a personal disconnect from pressured temptations, that might have us pushing limits when presented with delays, diversions, and even cancellations.

Fuel and the Law Alternate fuel reserve should be 45 minutes—the Federal Aviation Regulations say at normal cruise power setting—but it’s good to keep in mind that this is the final fuel and when the last of it slides through the engine, all problems become simple. You are going to land, right now, wherever you are! The government regulations spell out fuel reserves, but these certainly should be considered minimums. This is all they ever could be, because it’s impossible to write regulations that cover all conditions—especially considering the fickleness of weather. Having sufficient fuel is one of the greatest safety factors we can give ourselves. It assures the mental tranquility that is of paramount importance in weather flying. A pilot running low on fuel may make a hurried emotional decision that is wrong. It’s worth reflecting that fuel management is a major cause of engine failure. Good management means, for one thing, having enough fuel—not running out! It also means having the good sense to be certain the fuel valve is always on a tank with fuel in it. Airplanes have run out of fuel and made forced landings with the fuel valve on an empty tank, while fuel remained in another tank! The added advantage of being able to accept a wandering route from ATC,

without being unnecessarily concerned about fuel, makes weather flying an interesting, enjoyable experience, rather than a nervous and jittery ordeal. The ability to fly out of the weather area and go where it’s clear is a solid comfort of the first order. A pilot should never be in a position where all the bridges are burned and there is no way out. A fat fuel reserve goes a long way toward providing the necessary out. Desperation due to a dwindling fuel supply has undoubtedly caused more weather accidents, by far, than engine failure.

Fuel Again There are two ways to deal with fuel. One is to have lots of it. Most new airplanes are better in this regard, with some older designs also quite good. However, those lacking are usually designs with less performance, including lower cruise speeds, so we’re back to headwinds taking a bigger cut out of their capability. This issue is also magnified when flying lonely places, like the western United States, as well as in IFR flying needing adequate range and reserve. Certainly, if maximum utility is desired, an airplane’s manufacturer should strive to provide for the greatest possible fuel capacity when the airplane is originally designed. The second is to fly within the airplane’s fuel capacity by limiting the length of flights. This is restrictive, of course, because sometimes weather covers a big area that doesn’t allow a short-range airplane any alternates. Then there’s only one thing to do: sit and wait for better weather.

Instruments and Autopilots What else does the airplane need? Instruments to fly by, arranged in a good, useful fashion. Decades ago, panel layouts had instruments and radios stuck about cockpits in appalling, hit-or-miss manner. Thankfully, however, the industry began to cure this in the later 1950s, with the “basic T” primary instrument layout. So most airplanes today, save some older classics, have their flight instruments, as well as communication and navigation equipment—avionics—in a standard, close together useful placement. Good instrument flying requires constant visual scanning by the pilot, so logically, the shorter the distance a pair of eyes needs to travel to scan an instrument panel, the better. The basic key of instrument flying is to keep one’s eyes constantly roving —“scanning”—over the important flight instruments. When a pilot flies weather, the technique of flying by instruments should be so well developed that almost all attention can be devoted to the problems of weather, air traffic, and flight. However, with today’s integrated avionics and flight instrumentation systems, the workload is even higher. These demands are challenging for a hand-flown, single pilot aircraft, so ideally, an automatic pilot does the flying job. Not all general aviation airplanes are equipped with autopilots, consequently requiring careful

consideration before flying into a busy airspace environment. Even VFR, where basic hand-flying takes excessive workload, keeps our eyes inside the cockpit, not looking out for traffic, and this is especially challenging for less experienced pilots. If one is planning to consistently fly in busy airspace, even a very simple modern autopilot is not only helpful and a great enhancement to safety, it’s pretty much imperative. Autopilots have reached a level of sophistication that can be of tremendous benefit to all aircraft. They are light and reliable because of today’s electronic wizardry. The simplest autopilots, referred to as single-axis autopilots, include automatic roll control, heading select, course interception and following; this can be very helpful in today’s busy ATC environment for both IFR and VFR and in many cases, should be considered mandatory. If we add a pitch function that maintains climb and descent rates, as well as holds altitude, that’s a dual-axis autopilot. Three-axis adds a yaw damper, which helps stabilize yaw control of an aircraft, usually required in jet aircraft due to swept wing and other effects. In a light aircraft a yaw damper prevents sashaying through turbulence like a hula dancer. It facilitates a better flying aircraft and helps reduce the retching passenger syndrome. We now see digital autopilots that combine the current world of integrated avionics and flight instruments, even in light aircraft, and these systems are a pretty close match to many airline or corporate cockpits, except for automatic throttles—at, of course, commensurate prices. These autopilots easily do all the basic flight chores and then add programmed navigation in all phases of flight, including complex approaches. Modern airline and some corporate aircraft go that last step to automatic landings, using automatic throttle control—autothrottles— kicking out crosswind crab, landing, and rolling down the middle of the runway until the aircraft stops with automatic brakes, or the system is disconnected with the pilot back to good old manual taxiing! The autopilot, when operating normally, can do the manual labor of flying, while allowing the pilot to manage the flight, which importantly includes monitoring not only autopilot system function and navigation but the aircraft’s basic flight parameters. This is important, because not only can autopilots totally fail, they can do so partially, offering subtle failures, such as tracking a course improperly, sneaking off altitude hold, exhibiting unexpected altitude captures or failures to capture an altitude at all, and many more combinations. These simpler failures can be easy to miss, which is why we must constantly monitor basic flight parameters and electronic annunciations that verify the autopilot is conforming to what we are asking it to do. Also, some autoflight systems do not necessarily have blatantly obvious warnings of failure. The newer autopilots, connected to integrated navigation systems, are excellent, but now enter the world of the pilot having to program the route and altitudes properly, which feeds the lateral and vertical navigation of these advanced autopilots. This means the autopilot, once

placed into action, chases assigned altitudes with Vertical Navigation (VNAV ), as well as courses and headings with Lateral Navigation (LNAV ), as we have programmed them. Consequently, if we mess something up, the airplane is going to do it—it just reacts to what it’s told. Usually, surprises in automatic flight systems are due to pilot programming errors, whether it be a simple autopilot or the fanciest Electronic Flight Instrument System (EFIS) arrangements. It is important, from the first day we begin learning to fly automated cockpits, that we learn, or develop, some form of single-person redundancy—check and crosscheck—for programming and flying these systems. All this means a pilot should frequently check that the autopilot is behaving properly, whether the autopilot is simple or complex. This is a matter of not only scanning against raw data—attitude, altimeter and indicated airspeed—but also checking that we’re flying the programmed flight paths and navigation. Overall, however, these systems usually work beautifully, offering better pilot awareness as well as safety, because the autopilot relieves the high concentration of manual instrument flying, making scanning of a flight’s overall operation easier and better. In the complex world of instrument flight, an autopilot is almost a requirement; someday, they will probably be standard on all except pure sport airplanes, but we even see quite nice autopilots on homebuilt and Light Sport Aircraft (LSA ). These autopilots are certainly very desirable, especially if we use programmed navigation and fly in crowded airspace requiring precise flight for air traffic demands; they also give us time to look outside for other aircraft, terrain, and, yes, weather. They turn a busy hand-flying task into a more relaxed experience in which the pilot is potentially in better command of the situation and always ahead of the airplane. The lower a pilot’s experience level, when operating in demanding airspace and with more complex instrumentation systems, the more an autopilot becomes a serious need. Of course, a good copilot can also be a clever choice. However, an autopilot should never be a crutch for a pilot who lacks basic flying skills. This, however, becomes an ironic quandary. On one side we need autopilots to reduce the workload from more complex instrumentation and crowded skies, but on the other side they prevent pilots from learning and maintaining proficiency with good basic hand-flying skills. We take a more concerned look at this in later chapters, when discussing instrument proficiency and flying technically advanced aircraft.

Where the Instruments Live Our instrument panel layout has to display itself in some logical and useful organization. Each panel arrangement presents its own problems. The space available, control-wheel location, windshield height, and other such factors dictate how instruments can be arranged, but regardless of these problems, the primary

flight information instruments need to be grouped closely together, and easy to find and comprehend. Almost as important as the type and condition of instruments is their location. The basic T system of layout is used worldwide, no matter if they are good old round-dialed instruments—affectionately referred to as “steam gauges”—or modern electronic flight instruments displaying primary flight data orientated the same way. It has been proven for over half a century of flight and is found, in principle, on every airplane designed for instrument flying from light general aviation to the most modern transport aircraft. This system positions the artificial horizon top center and the directional gyro or Horizontal Situation Indicator (HSI ) directly below it. The altimeter is placed right of the horizon, and the airspeed indicator is to its left. This location of the artificial horizon—the attitude instrument—in the most prominent and easy-to-use location is a testimony to the importance of attitude flying. With round-dial instrumentation, we find the turn coordinator or turn and bank on the lower left, Vertical Speed Indicator (VSI ) on the lower right, and the whole compliment is referred to as a “six-pack” instrument setup. The important point is that the instruments should be as nearly in front of the pilot as possible, and they should be in clear view and not hidden by the control wheel or anything else. Flying the Airbus side-stick system, now seen on some popular general aviation aircraft, leaves a wide-open view of the instrument panel; one can even have a laptop writing desk to keep notes. The basic T instrument location derives from developing an easier to scan instrument panel arrangement, which in past decades referred a lot to hand-flying. However, even when flying on autopilot, we still need to scan and monitor instruments with the same efficiency as when flying without autopilot. As mentioned, the key instruments are the Artificial Horizon, o r Attitude Deviation Indicator (ADI ), for bank and pitch reference, and the Directional Gyro (DG ) for heading. Round-dial directional gyros are fast becoming of sketchy accuracy when flying in action-packed airspace, because we have to constantly worry about resetting the DG. Before today’s digital electronic instruments, the big deal for DG replacement was the HSI, which is a big advance and help, because it has heading and navigational information all together. Also, the heading is slaved to a remote pickup and stabilized, so one doesn’t have to constantly worry about resetting the DG. Airspeed, vertical speed, and altimeter are really reference instruments, and their action is a result of things that appear first on the artificial horizon and directional gyro. If the key instruments are watched closely, the airplane never gets a chance to go very far from the “straight and narrow.” Frequent scanning and immediate correction of excursions from the desired flight path give the feeling that one has the airplane in a narrow corridor, boxed in on all sides, unable to escape and fly off on its own.

Because rapid scanning prevents the airplane from getting far off course, any correction the pilot needs to make will be small and therefore easy. Problems start when a big bank or pitch angle is allowed to develop. If this happens, the heading, vertical speed, airspeed, and altitude go off, and the pilot has a handful trying to get the airplane back where it belongs. Scanning is not difficult if practiced. Small corrections and never allowing the airplane to wander far make flying simple and relaxed.

Clean and capable classic round-dial, IFR-capable instrument panel. This 1965 Piper Cherokee is a nostalgic beauty, but is fully capable today with its clean and concise panel nicely retrofitted with a good communication and navigation radio, transponder, audio panel, and the real gem, a Wide Area Augmentation System (WAAS)-capable GPS/radio combination. This airplane can fly the many new GPS-based instrument approaches and has precise area navigation with top-shelf accuracy. With a good hands-on pilot of sensible cockpit discipline, this airplane offers a lot of safe and enjoyable utility. (PHOTO BY RUSSELL J. KELSEA)

A top-notch, modern electronic Primary Flight Display (PFD). It is clean and concise, with excellent but not cluttered features. Considering the basic T instrument arrangement, this PFD’s clear design shows the same layout for primary instrumentation; compare it with the round-dialed instrument panel pictured above. Far left is airspeed, center is the ADI, with the altimeter to the right and the Electronic Horizontal Situation Indicator (EHSI) below the ADI. The only real difference is placement of the VSI to the right of the altimeter, and the standby instrument gyro is elsewhere in the panel, depending on the design. (PHOTO IMAGE COURTESY OF AVIDYNE CORPORATION) It is very important that the pilot be well versed in attitude flying. There are reams of information and instruction available, and an instrument pilot should take advantage of them to become a good attitude pilot. Attitude flying, in one simple example, is the difference between attempting to maintain a specific airspeed by chasing the airspeed indicator, rather than by keeping the horizon bar in a position that will give the specific airspeed desired. If speed is too high, the nose is raised slightly with reference to the horizon, thus producing a small but positive airspeed correction. Practice soon teaches what attitudes will provide the desired airspeeds, heading changes, descents, and climbs in small, easily controlled increments. More importantly, it will help keep airplane movements small and prevent large oscillations that are difficult to recover from. Well-

arranged instruments, combined with good scanning and attitude flying, make instrument flight precise and simple. For many who learned on round-dial instruments, the VSI was very much in the loop, and today may be an overlooked instrument. Primary instruments were originally a turn and bank, airspeed, altimeter, wet compass, and VSI, but no artificial horizon, so learning those basics made the VSI a useful part of flying. The VSI in today’s high-tech world still has merit, especially when hand-flying without a flight director or if we’re down to basic standby instrumentation from primary instrument failure. If the VSI is steady on zero, there cannot be much wrong with the airplane’s flight; vertical speed cross-checked with the DG is an easy, quick look that things are okay—we’re straight and level. A good vertical speed instrument, whether the “old-fashioned” round-style or one on a modern PFD display, is a valuable instrument to catch your eye. When the VSI starts up or down, we had best take a look at the other instruments and see what’s going on. It is also valuable in judging altitude level-offs, by monitoring excessive climb or descent rates. On approaches with vertical guidance it helps us judge head or tailwinds by comparison to descent rates versus groundspeed. It can also tell us if the air mass in which we’re flying has excessive vertical action, such as in gusty conditions and potential winds-hear issues. Earlier VSIs had some lag time, but the new ones on electronic instrumentation are quicker, like the Instantaneous Vertical Speeds (IVSI ) of higher-performance aircraft, which enhances a VSI’s value. A glance at the VSI and heading, especially in compromised flight, can tell us a lot.

We Can Keep It Simple Despite today’s obsession of electronically displayed and enhanced instrument panels, we need little instrumentation to stay upright and do a fair amount of good instrument flying, if we are properly trained and practiced. A little history helps us dispel any misunderstanding that without the fanciest gadgets we’re doomed. So what kind of instruments does one need? The extent and sophistication of the instruments is determined by the amount and kind of weather a person is going to fly. A pilot can fly some pretty awful weather with quite simple instruments, but that’s a very busy pilot, and the job accomplished won’t be a neat, precise one. My own (RNB) instrument flying began in 1931 with an airspeed, vertical speed, and a turn and bank. I taught myself how to use them by following a little pamphlet-sized book called “Blind or Instrument Flying?” which was written by an airmail pilot named Howard Stark, one of the important pioneers of instrument flying. Charles Lindbergh credited Mr. Stark’s writings as guidance to his learning instrument flying—and one of the key reasons he made it to Paris from New York, on his famous 1927 flight in his “Spirit of St. Louis.” His only attitude gyro

to keep him upright and from losing control, as he flew through hours of clouds and dark over the North Atlantic Ocean, was a little 2¼ inch diameter turn and bank instrument. I flew actual instruments, too, but it was all restricted to climbing up through or flying on instruments toward clearing weather. It was done without radio by simply holding a heading. This wouldn’t be possible today in most parts of the world, because of airways and traffic, but back then there wasn’t any traffic, nor any airways either.

A Little More to Do a Lot From that simplicity, in 1937 I graduated to a Douglas DC2; the only addition to its instrument panel over my little two-place, 90 horsepower Moncoupe’s panel was an artificial horizon and a directional gyro. Along with this, there was, of course, a radio to follow beams and a loop turned by hand to read bearings, which said the station was at one end of the bearing or the other, but not at which one, because the loop didn’t have direction-sensing capability. With this setup, we flew weather, lots of weather. The landing minimums at Newark, New Jersey, in 1937, were a 300-foot ceiling and ½-mile visibility! Takeoff minimums were 100 feet and ¼-mile! It wasn’t done very sophisticatedly, either. We flew the radio beam toward the station, which was down in the Newark meadows near Elizabeth, New Jersey. We crossed over the center of the station, called, in the slang of the day, the “cone of confusion,” at 800 feet, chopped the throttles, shoved the nose down, and descended quickly to 300 feet; then we looked into the black night for a row of red neon lights that led to the black runway. What’s so surprising, in retrospect, is that we did it often and successfully. Of course, a DC2 could fly at 80 miles an hour; that makes a big difference from a jet that you don’t get under 135 knots. All this is to show that a lot of weather can be flown with a primary flight group, an artificial horizon, and a directional gyro. We did, in those times, do a lot of practicing using the primary flight group only; needle, ball, airspeed, vertical speed, and every instrument check we took included an approach using only the primary instruments. I’m afraid this isn’t done as much as it should be today. Personally, I like the turn and bank indicator over the turn coordinator and believe the flight cues more true using the turn and bank, but perhaps that’s all because I was “raised” on a turn and bank. When I bought my Cessna, it had a turn coordinator, which I promptly replaced with a turn and bank. I just don’t feel that the artificial horizon look of the turn coordinator is relating truthfully to turn. Today, however, many light aircraft autopilots are sensed from turn coordinators, so they must stay. Either way, we have to practice and be competent flying whatever backup instrument flying displays we have, whether turn coordinator, turn and bank, or artificial horizon, possibly tucked into an obscure corner or out

of the normal panel scan. Our old artificial horizons did about what today’s can. The directional gyro was the bore, because, like simple DGs of today, it didn’t have any north-seeking ability and needed to be set to agree with the compass. Gyros precess and must be set frequently. They must be set when the airplane is level and not turning, with the magnetic compass settled down so that it’s reading accurately. In rough air, while working on holding a course, this can be difficult to do. Some gyros precess more than others, depending, generally, on the condition of the gyro. If it is well maintained and periodically overhauled, and if the vacuum source, in the case of vacuum instruments, is set to give a constant value of vacuum, a gyro can hold a heading for 15 minutes or more without much attention. A point to remember is that once a gyro starts to precess, the rate of precession increases the more it precesses; so it’s wise to reset a gyro before it gets too far off. It is wise, also, to rate your DG by keeping a record of its precession rate. Set it carefully on a smooth day, then fly for 15 minutes and reset it, noting how many degrees it was off from the previous setting. Keep a record, and when the rate becomes too high —about a 10-degree error in 15 minutes—it’s time to have it overhauled. The manual DG has stuck with us for decades, and again with a round-dial, older panel we may still have a precessing DG. So now we know how to handle it.

Things Can Be Better In modern instrument flying, which requires precise following of airways, a DG may add appreciably to the cockpit workload, and as mentioned earlier, it might not be up to the accuracy we need for more crowded airspace and their precise demands. Instrument designers have cured the problem by wedding the directional gyro and compass so that a north-seeking unit constantly keeps the gyro’s heading adjusted for magnetic north. The important point is that once the gyro is set, the pilot need never worry about resetting it; we call this a “slaved gyro.” The heading information is always precise without the turning error, run ahead, and hold back of a magnetic compass. This intelligent type of gyro has been one of the biggest boons to precise instrument flying, and it reached aviation technology at about the time that heavy traffic and more narrow airways called for better flying. This, now, is the HSI we talked about; it’s one of the first “extra” items we would add to upgrade a traditional, round-dial instrument panel with a nonslaved DG. Today we can take another jump over nice mechanical HSI units with an Electronic Horizontal Situation Indicator (EHSI ) or go further to a Primary Flight Display (PFD ), which includes both the EHSI and Electronic Attitude Director Indicator (EADI ) , with more parameters of information. Their sensing is derived from a nice digital Attitude and Heading Reference System (AHRS ) that replaces the more maintenance-sensitive mechanical gyros, wires, and slaving units. Added to this is

a n Air Data Computer (ADC ), which takes standard pitot and static inputs, refines their errors, and produces very accurate data, allowing more precise instrumentation, autopilots, and related guidance. Sometimes these two devices are combined into one unit, being called an Air Data, Attitude, and Heading Reference System (ADAHRS ); an acronym field-day. These marvelous little computers are what makes the new electronic instrumentation so concise and capable, all with new levels of accuracy, reliability, and lightweight design for smaller aircraft. This type of accuracy has been standard with larger aircraft like airliners and corporate jets, which also use air data computers, but instead of AHRS for their gyroscopic needs they have historically used Inertial Reference Units (IRU); however, to reach today’s average GPS accuracy for navigation, the civilian IRU navigation systems had to be tightened with GPS interface. To sum up at this point: The minimum one needs for instrument flight is the “primary flight group” (the historic name for T&B, airspeed, altimeter, VSI and wet-compass), plus an artificial horizon and DG. With this, one can fly instruments and shoot low approaches; with the addition of a slaved gyro or HSI, however, life becomes easier—and much easier with an autopilot.

Even Better Technology took us further by adding intelligence to the artificial horizon, directing us with a “command” cue in the artificial horizon, to our desired course, usually an ILS’s localizer and glideslope. To explain a bit, if we fly an ILS with a horizon and DG, the localizer needle is located in another instrument, either a separate dedicated one or an HSI. As we fly headings toward the localizer, once we’re on course we try to find a heading that will keep us on it, by a process called bracketing. How much to turn and when to turn is a matter of skill and, to some extent, guesswork. As Dave Little, an American Airlines captain in the early years of the airlines, who had done a great amount of research in instrument flying, said: “Flying down a localizer this way is like following the white line on a road by watching it through a hole in the automobile’s floor.” Now we have command bars in artificial horizons that have computed information fed into them. They discover how far off course one is, what drift there is when an airplane is wandering from the course, and then say, “Turn now and this much.” The information is presented in such a way that one has only to follow a little airplane command symbol or bar, superimposed on the horizon, matching one with the other, and by so doing a pilot stays right on localizer and glide path. It is called the “Flight Director.” The pilot still refers, although only periodically, to the basic localizer/glideslope instrument to make certain that the flight director is doing its job. Occasionally, there are times when a flight director command just doesn’t add

up to what we see on our raw data. (Raw data is what the ILS needles, airspeed and altimeter, plus indications off the basic attitude flight instruments are telling us. This lets us verify if the little computer that guides the flight director is doing its thing properly). When there is any doubt between raw data and the flight director, go with the raw data. This is called “flying through” the flight director; following instead that accurate raw data versus erroneous flight director commands. This can get a little confusing, and requires strict discipline, in that we are fighting the urge to follow the easier to fly flight director bars or cues, while w e must focus and fly the accurate raw data. This, we may add, only does any good if we know the attitudes and power settings necessary for whatever parameters we need. That’s why we need to first fly an aircraft without augmented information such as flight directors, allowing us to establish basic knowledge of what attitudes and power settings give us those needed performance parameters. When equipment of this sophistication came aboard jet airliners in the later 1950s, pilots were allowed to shoot hand-flown minimums as low as 200 feet and ½-mile visibility. The flight director was required for these approaches, but today the hand-flown approaches of professional operations are often limited to ¾-mile visibility; below that the approach is required to be flown by the autopilot, which we call a “coupled-approach.” Obviously, if the flight director and autopilot are not working, minimums are higher and this is one reason why airliners carry duplicate systems. However, when flying privately, we can fly to 200 feet with a ½-mile visibility—assuming the approach is approved for such—with just an ILS indication in a separate VOR/ ILS indicator; an HSI or flight directors is just icing on the cake. These minimums are known as Category I (Cat I ), with 200 and ½ the lowest criteria for Cat I, assuming the approach is approved for these lowest minimums. It is something to think about for our personal flying, considering professional operators with often better equipment, more experienced pilots, and constant currency from operations and training, have more restrictions. In any event, with equipment giving us both lateral and vertical guidance, whether it be an ILS or GPS-based approach, it is easier to fly a 200-foot ceiling with a ½-mile visibility with that equipment than a 400-foot ceiling with a mile-visibility without it. The computer data fed into these flight director systems is often the same as that given to the automatic pilot when it is set up for making low approaches; if the airplane is equipped with both, one system is used as a check against the other. When we start going to lower minimums and automatic landings, such as in airliners and higher end corporate aircraft, there are usually two or three autopilots, with commensurate comparison computers and displays of operation. Three may seem excessive, but when you are comparing two—whether autopilots or something else like an ADI—there’s quandary as to which one is bad. But with three, then you get a majority decision. Outwardly, it seems very complicated, but in reality, these systems work precisely and rarely with a flaw. However, despite

the redundancy, these operations still must keep an eye on raw data information, which in advanced instrumentation is usually displayed on the EADI and/or PFD. The flight director approach combined with autopilot came to our experience with the Boeing 747 in 1970. This reduced minimums at certain airports to Category II (Cat II ) of 1,200-foot visibility and 100-foot ceiling. Cat II is flown with an autopilot “coupled” approach to 100 feet, without the requirement of autothrottles or autoland, which if without upon reaching minimums the pilot disconnects the autopilot and lands manually. This is a successful procedure, and when reaching 100 feet, most of the approach lights are behind us, which is why Cat II/III runways have Touch Down Zone Lights (TDZL ) physically in the runway. The only task was clicking off the autopilot, flare for landing and the procedure works great. However, despite the slight bruise to aviator ego, if an airplane has autoland capability, the best deal is to use it. Category III landings, today, have whittled minimums to no ceiling requirement and 300-foot (75 meters) visibility, but of course they are totally automatic, with autoland and autothrottles; an elegant process. By the way, this visibility is measured along the runway with three and sometimes four Runway Visibility Range (RVR ) devices, called transmissometers. Each unit has little light-sensitive sensors that analyze light reception, which through computerization is processed into an RVR reading measured in feet or meters, depending on where in the unit-world it’s located. Control tower visibility is usually nil, being stuck up high in the fog. There are actually three levels of Cat III operation—IIIa, IIIb and IIIc. All visibility rated, IIIa is 600 to 700 feet or 200 meters, IIIb over 300 feet or 75 meters, and IIIc is plain old zero! One of the reasons IIIc, or zero visibility minimums have yet to happen operationally is a function of finding taxiways and a parking place in the fog. There are required centerline-lighted taxiways, specifically illuminated, that at least guide us off the runway and down the taxiway away from the runway environment. The rest is an interesting game of carefully following airport diagrams, checking headings, and squinting at taxiway markings. It keeps two or more pilots pretty busy and sometimes a bit edgy. One day in Paris, on one of those foggy European mornings, two aircraft came nose to nose as they oozed through the murk. They saw each other, stopped—usually in such lousy visibility we taxi with at least the aircraft’s taxi lights on—then stared at each other for nearly an hour waiting for tow trucks, also lost in the fog, to find them and untangle the mess. The many approaches we’ve made to these low minimums were easier, more relaxed operations than flying by hand to a much higher minimum. The autopilot does the work and we have lots of time to scan the cockpit and double-check instruments. You have an understanding of the entire action, rather than being mesmerized by the few instruments that one uses to keep in the slot when flying by hand. When the runway lights come into view, there’s no worry about sensory illusions and getting too low and below glideslope on the visual part of the

approach, because we’re there! Right at the runway, and in a few seconds rolling down the centerline. It’s the way to do it. However, and again, always remember that during these sophisticated approaches, a pilot should double-check the raw data, checking to see what the approach’s primary guidance needles and the flight instruments are saying, making certain that the fancy electronics are on the ball. Overall, Cat II/III is not usually a general aviation operation, instead mostly for airlines and certain corporate aircraft. However, they are worth understanding, especially because these lower minimums instigate a great deal of the technology, techniques and standards we use in all our instrument approaches. Departures are another area where the FAR’s tell commercial operations they have minimums; usually visibility, but at times ceilings due to terrain issues. What’s important with any instrument departure is having some sort of valid departure procedure that keeps us clear of obstacles and terrain, as we clamber for altitude. This can become a gray-area when operating from some airports, because if not operating commercially we can depart in very poor visibility—for that matter, nil, if one is really that itchy to go. The prudence of this varies with each event, and crosses swords with the real benefit of general aviation which is having the ability to use thousands of local airports. However, when the weather is lousy, the discipline of low-visibility operations is the same, whether an airliner in Seattle or a light aircraft at a local airport on a foggy morning. If we’re taking off in low visibility and don’t have adequate runway lighting, and especially centerline lights, the heading (DG, HSI, etc.) becomes an even more important reference. We reference it constantly as we rush down the runway, eyes in and out between DG and what we can see outside. However, once we rotate the airplane we’re on that attitude indicator, with reference to heading, airspeed, and altimeter to make sure we’re climbing, and under control. As a side note, even in the world of high-end aircraft sporting excellent equipment, initial rate of climb for landing gear retraction is altimeter-referenced, due to post rotation error with some VSIs. In the first years of the big jet airliners, one flight was quick on the gear and instead of climbing away towards another glamorous, early jet-era flight, they ground to a halt at the runways end. Fortunately, nobody was hurt, but it was an expensive lesson that kept the sheetmetal shop busy for quite a while. Around the time I (ROB) soloed our Cessna 120, in the summer of 1965, my father climbed in one day and said we should do an instrument takeoff. Confused—it was a lovely clear morning in eastern Pennsylvania—he explained the process and soon we were at the end of the grass runway at Van Sant Airport, which kind of rolled and leaned, with an instrument hood over my eyes and the WWII-vintage DG and artificial horizon spun up, set and ready. We trundled down the runway and somehow kept the little tail wheeled Cessna straight, gingerly easing into the air, with its 85 horsepower clawing into the summer sky. As those years of innocence turned into an aviation career, when pointed down a fuzzy runway in lousy visibility, with all the formality of

equipment, crew, briefings, and procedures at hand, I’d remember that moment at Van Sant’s, my father and I squeezed together in our little 120’s narrow benchseat.

The Future Will Be Even Better We have reached an era when even single engine general aviation aircraft can match navigation and instrumentation on par with airline and corporate aircraft. Certainly there are performance and environmental advantages to bigger and higher performance aircraft, but overall, general aviation offers impressive utility. With the hopefully successful Next Generation Air Traffic System (NexGen) not far away, these well-equipped light aircraft will fit into the envelope just fine. When the industry honed the integrated avionic and autoflight systems with autothrottles, it allowed ultimate efficiency of fuel burn and flight path orchestrated through the electronic brains of Flight Management Systems (FMS). General aviation EFIS systems, with integrated autopilots, have just about everything these large aircraft offer—and sometimes more—but without autothrottles. For now, however the pilot with a nice six-pack of round-dial instruments (airspeed, attitude indicator, altimeter, VSI, and preferably an HSI, with adequate navigation and communication) has a fine instrument-flying platform. It may sound untrendy to suggest this, but trendy instruments are expensive, so our guess is round-dial panels will be around for quite a while. When an upgrade is possible, it can be done whole hog, with a fully integrated glass cockpit and autopilot, or more frugally, as upgrades to a nice approved GPS–WAAS system and maybe a simple autopilot. (WAAS means Wide Area Augmentation System, which allows IFR accuracy for a GPS equipped aircraft by using remote ground stations to tighten the GPS signal accuracy; at this writing, within three meters 95% of the time.) There will remain limits to the amount of instrument flying possible, just as the pilot with a little more equipment is limited, though not quite so much, and the one with everything is limited even less. The equipment, humble or extensive, must be used properly, with the pilot’s proficiency honed to a fine edge through both knowledge and practice.

A beautiful example of a full-house, Technically Advanced Aircraft’s (TAA) instrument panel, including a good autopilot. The standby instrumentation is behind the left horn of the “captain’s side” control wheel, which would be in clear view of the pilot when seated. (PHOTO IMAGE COURTESY OF AVIDYNE CORPORATION)

The Protected Airplane A new twist available in conjunction with aircraft having advanced autopilots is the introduction of “smart” autopilots that, while the pilot is hand-flying, input increasingly heavier control force inputs and/or corrective pressures, when the aircraft begins to exceed predetermined aircraft parameters. They are not only reminders to the pilot, but also coax a pilot back to normal flight with a selfrighting tendency. Then there is a button that when pushed will “right” the aircraft to straight and level flight, assuming it was pushed before the aircraft was too far out of control. Impressive technology with definite value, but these technologies should not be a crutch for a pilot lacking basic flying ability. However, because these protective systems are autopilot-based, autopilot failure reverts the aircraft to nonaugmented hand-flying characteristics, so the pilot is back to square one; a shock if a pilot is dependent on these systems. There is no way around the fact that we will always need to have competent hand-flying skills. Nor can we fly aircraft assuming failure possibility is so remote we can take the risk they won’t fail. We can’t think that way in aviation—again, we have to be capable of handling the worst scenario

that is controllable with of the lowest common denominator of equipment. As to instrumentation features, we have PFD displays now offering “synthetic vision,” computerized terrain presentation derived from GPS data, and “enhanced vision,” which sees through clouds and dark. These are magnificent additions, and potentially quite useful, but again are usually not approved primary flight information, such as flying over terrain in instrument conditions or finding a runway below minimums. However, on high-end systems of mostly corporate and military aircraft, we see these systems being integrated into low-visibility operations—so, we can only surmise what the future may bring. Oh yes, while not an instrument, we feel the ballistic parachute is worth mentioning. It is a unique and helpful feature, especially for events we can’t do anything about, such as an engine failure at night over bad terrain or mid-air collision; but realizing, for many reasons, the parachute is still not always going to be successful. Most importantly, it is our opinion that a ballistic parachute should not be there to save a pilot from the inability to fly an aircraft in conditions their ratings and judgments place them, be it something as simply inappropriate as running out of fuel, or maybe very demanding such as turbulence, icing, or thunderstorms. In thinking of GPS navigation, if we’re depending on it, and not following with a map, and the GPS and/or display quits, where are we? If it’s a nice, sunny, clear day, we have time to flail around the cockpit for that backup sectional chart or handheld GPS. But dark and IFR, especially if our problem is electrical and we’ve lost that nifty autopilot, among other things, the situation can turn into a real mess. You’ll have to work that one through for yourself, turning on a backup electronic device or using a chart. If your panel doesn’t have emergency lighted standby instruments, you’ll have light from that flashlight between your teeth, as your hands are busy flying the airplane. Either way, in much of our general aviation world, we should consider having a sectional chart nearby, folded to our route and between the front seats. By the way, what happens on the airlines as to IFR charts? With glass cockpits, we went through that chart thing of keeping them in our flight bags. Then, after some interesting fandangos occurred that couldn’t be handled by fast typing on the FMS, the requirement was to keep a chart nearby, ready for action. It will happen—trust me. So, it is imperative for the pilot with the fancy equipment to maintain proficiency with the simpler equipment, namely the minimum we use for a last resort backup. The primary flight group (airspeed, vertical speed, turn coordinator or turn and bank, and in these days an artificial horizon) is the most reliable, always being the standbys if the other instruments fail. For more than 75 years, the turn and bank, and later the turn coordinator, has been found on every instrument panel with which any instrument flying was done, from Cubs up to airliners and jet fighters. They are beginning to disappear, being replaced by a standby horizon and some really nifty electronically displayed units, with self-contained airspeed,

altitude, and longer lasting backup batteries exceeding the anemic 30-minute required minimum. Many general aviation airplanes still have turn coordinators or turn and banks; we weigh in with the opinion that the turn coordinator is goosier to fly than a turn and bank, but both keep working, no matter what the aircraft’s attitude. If a turn coordinator or turn and bank is on your instrument panel— indicative of a round-dial, six-pack instrument setup—it’s a good idea to cover the horizon and DG/HSI now and then, and have a practice session with only that rate-of-turn instrument. Remember that turn coordinators are not artificial horizons, but gimmicked-up turn indicators, and should be flown as such. Without the ability to successfully hand fly our standby gyro instruments, redundancy to controlled instrument flight is totally blown. The result is simple— loss of aircraft control and tragedy, instead of safe landing in a flyable airplane. Besides its necessity for survival, staying current with standby gyro instruments is both an excellent airborne and simulator exercise, its visceral function teaching superb sense of aircraft control while flying instruments. It makes us far better pilots, even when everything is working normally. Today’s computerized glass cockpits with integrated avionics are wonders to behold and do impressive things, but these systems are still subject to failure and, because of their complexity, a human can improperly program the system. Pilots, for a long time, will be required to monitor that all is well and the simple facts of where we are, how high in relation to terrain, and the airplane’s flight condition. It’s wise to remember that the pilot is ultimately responsible for avoiding the terrain and guiding the airplane on the path it is supposed to follow. Some computer people give the impression that airplanes can be flown entirely by electronic systems, doing a better job than humans. This is pretty much true, but not in an unlimited sense. Ask the question, “Would you fly on an airliner without pilots and only flown by computers?” The answer is usually obvious. So we must always be skeptical and double-check our situation.

Power for Instruments Instruments, however, are no better than their power source. Some are vacuumpowered and others electrical. It is required—and for good reason—to have an alternate source for our primary attitude indicator system, in case this critical source fails. This can be supplied in a number of ways, depending on whether the failure is the indicator itself or the source that drives it. If we use a round, vacuum-powered attitude indicator, it would be nice to have a dual vacuum pump system or a multi-engine aircraft. To back up an instrument failure, as we’ve mentioned, we include a standby artificial horizon or turn rate instrument run by electrics, namely the battery. Now, we have the marvelous electronic “glass cockpit” PFD screen, with not only attitude indicator, but also displays of airspeed, altitude, VSI, trends of flight

path, heading, navigation, and so forth, from those separate little computers we’ve mentioned like the AHRS and ADC. They live in the fuselage and use pitot, static, temperature, sense the earth’s magnetic field, and figure out the aircraft’s attitude. Throw in a GPS box and we have navigation. Then there are other little computers to pull it all together, and figure out inputs for things like flight directors. All these devices are little digital wonders, with amazing probability from failure, especially as compared to mechanical gyros and all that’s related to them. However, even with the reliability of these newer devices, the quantity and combination of their installations create multiple opportunities for failure; a field day for statisticians obsessed with failure-probability. The short story is that, it’s nice to have second units of these devices and whatever else makes them tick, but that isn’t cheap and adds weight. If we have a full integrated avionic system of PFD and Multi Function Display (MFD) on the instrument panel, the latter showing us navigation, engine and system indications, weather and is a backup to our PFD, and vice-versa through split screens. Still, we need—by common sense and regulation—redundancy to all the screens and/or little boxes, should they fail in critical combination, so we’re back to the standby artificial horizon attitude indicator; the standby choice for EFIS equipped aircraft versus the turn coordinator or turn and bank. But that’s not all! Because these EFIS equipped airplanes are all-electronic operation, we need two battery sources, and some aircraft even have dual alternators. Without an alternator and totally on battery power for the standby attitude indicator, regulation says we need at least 30 minutes run off battery, but that can go pretty quick if we’re in IFR conditions, need to find an airport and shoot an approach, all on standby instruments and now being hand-flown because the autopilot doesn’t work on standby electrical power. The only time we’ve faced such an event was in the simulator. The most advantageous setup has us in touch with ATC, who we call and declare a total power loss emergency, ask for vectors to the nearest approach, which hopefully is an ILS if we still have such equipment operating (we do in airliners and other advanced aircraft), and indicate we won’t respond unless absolutely necessary. That saves battery. We want to fly a close-in, tight approach, but not get so frantic we overdo it, get high and fast, and then have to go around. If no close-by airport or approach, the process gets very interesting. There have been some dramatic situations and accidents because electrical systems lacked sufficient backup. The summary is that if an airplane is going to be used for instrument flying, its primary attitude instruments, and the electrical system should have a useful backup. It is also worth bringing along one of those fine standby handheld VHF radios, some with VOR navigation, and a small portable GPS; and some interesting back-up potentials off personal electronic devices is coming along but with legality and reliability issues still in flux. All this is quite a contrast to the system on my (RNB) Pitcairn Mail-wing, vintage 1930, which had as my sole instrument flying gyro a turn and bank

powered by a venturi that was mounted on an exhaust stack with five tiny holes in the stack just ahead of the venturi’s entrance. These squirted hot exhaust gas over the venturi and prevented it from icing up; such a rig might not have been a bad alternate source for the vacuum systems we use on our attitude indicators, but the retrofitted electronic glass displays of today have certainly changed that path of thought. These days, people might shudder to think of venturis sticking out, causing drag, and getting iced up. But an interesting comparison is the extendable Ram Air Turbines (RAT) that modern jets have for last-ditch hydraulic, and sometimes electrical power. They automatically extend from the aircraft belly in response to various criteria of total system loss, spinning a prop that drives a pump. They are like the little wind-driven generators seen on some light aircraft from the 1930s into the 1950s—good old common sense in a fancier package. Other than gyro instruments and their power sources, we need to remember the airspeed indicator and altimeter are “powered” by pitot and static tubes that bring in pressure and static air. Because it’s very difficult to extensively fly instruments without airspeed, we need to remember that even modern glass cockpits also use good old pitot and static for their complex systems, so it’s important to keep these sources clean and operating. Careful inspection is necessary before flight to be certain that the pitot tube and static source are free. A bad static source will affect the altimeter, vertical speed, airspeed, and some pressurization systems. Among other things, mud daubers love to make little nests in the end of pitot tubes. I (ROB) had one constructed in a Cessna 182 pitot, just overnight in Far West Texas. That’s why we should cover pitots—which obviously I forgot to do! Among the other things airplanes should have when flying instruments is the previously mentioned pitot heat. Airlines feel that pitot heat is so important that they use it whenever they are flying; it is automatically actuated with engine start on more modern aircraft. It’s important to check our aircraft’s manual on this, as in some aircraft the pitot heat is modulated cooler on the ground (ground sensing switches on the landing gear), while others are either full-on or off, which when on without airflow from flight can burn out the heating elements. Either way, once airborne, whether cloud or no cloud, summer or winter, it’s good habit to always have it on, in case we need it and are sidetracked at a critical time. A temperature drop can take place inside a pitot tube and produce ice or slush if there’s visible moisture. Even water from heavy rain can cause an erroneous reading in pressure instruments. Ice, of course, can knock out an airspeed indicator completely. Pitot heat is a must! If the static source is within the pitot head, then the pitot heat will take care of it; if the static source is flush on the outside of the airplane, as most are today, it will not be closed by ice, but it can be blocked by slush being thrown up from a nose wheel and then freezing, or by human-made things, such as tape put over the static holes during airplane washing or servicing. This can be very serious,

remembering some preventable fatal airline accidents from covered or blocked pitots and static ports, as well as quite a few incidents with happy endings. With today’s general aviation aircraft having complex electronic flight and instrument systems, this is a situation we must heed seriously. Once you break ground with plugged pitot and/or static, where some things are not working, false and conflicting instrument indications show up, autopilots may or may not function correctly, and it’s absolute chaos for the little electronic brains of EFIS-style instrumentation. Then, as we try to figure out what’s wrong and focus on flying very screwed up flight indications, it’s made more chaotic with warning bells, horns, and lights signaling their confusion. In the dark of night or during focused IFR in clouds, the solution is cool over chaos, while flying attitude and power off primary flight instrumentation, until we’re back on the ground. The FAA requires that the condition of these instruments be checked periodically for leaks and deterioration of the tubes in the system. Instrument flying is important in weather flying, and while a person may or may not be proficient, all pilots can make certain the instruments they are using will be in top shape and functioning properly.

Lighted Well It is important to have the instruments lighted properly. With modern glass cockpits, this has become much better, if not nearing moot. Again, however, we still have a lot of fine flying with traditional instruments, so lighting is still of concern. This means that at night the entire area of their dials should be illuminated without any shadows. There should be no glare, and they should be visible in a minimum of light. It should not be necessary to turn the lights up bright or to have excessively bright lights in order to see the instruments. Some airplanes we’ve seen require such bright panel lights to wipe out shadows on the instruments that outside vision is impaired. The pilot is like an actor trying to see the audience through bright footlights. The bright light not only cuts out what can be seen outside, it also deteriorates a pilot’s night vision. Bright lights also have a way of reflecting in windshields, so that as a pilot looks outside, the instrument dials grin back from the windshield or side windows in a most annoying way. On the subject of night flying, it’s worth realizing that night VFR flying is instrument flying to a large degree; while a noninstrument pilot can legally fly at night, a clear night with good visibility and some sort of horizon will be required. It can be an awful shock for a pilot to leave the end of a runway and to be suddenly enveloped by a pitch-black night with no horizon or reference to fly by! If the horizon is not clearly defined, and there is any risk of clouds, it’s easy to slip into a cloud and never realize it until all outside reference is gone and we’re on instruments! An instrument rating is a strong safeguard. The VFR accident rate is much higher during night flying than during day flying.

Paperwork and Gadgets Are Equipment, Too Almost as important as an airplane’s instruments is the paperwork associated with instrument flying. Whether we’re flying older electronic navigation of a VOR, a line on a GPS screen with minimal position features or EFIS equipment with terrain or maps underlaying the route, we need up-to-date maps, radio facility charts, and instrument approach plates as an adequate backup. If we’re VFR, we mean sectional maps that show terrain and important features: mountains, elevations, rivers, towns, airports, and such. A few sectionals backing up IFR isn’t a bad idea, either. Too often the only chart used is the radio facility chart, which doesn’t show topographic features and a lot of other useful information. Reference using real maps is important for many reasons, such as avoiding mountains, locating airports in relation to towns, the water areas that may affect weather—a host of things. For safer flight, maps are needed. Added to paperwork comes today’s world of portable GPSs, personal electronic devices, and numerous other gadgets to complicate the cockpit. With them come wires and plug-in attachments. In short, whether we are using paper data or these electronic items, we need to have a place for them in the airplane. There’s nothing worse than charts, gadgets, and wires scattered all over the cockpit. Good flying, instrument or visual, requires good housekeeping. This means a little preparation in advance, before takeoff. For electronics, it is nice to find good efficient mounts, preferably not blocking vision of the instrument panel or outside visibility. To replace wires, anything we can work from a wireless source is good, as long as the wireless connection is adequate for the level of reliance we need from the device. For charts, we get them out as needed for the flight, stack them in order, folded and secured (little clips are useful for this). We probably use a flight-planning form and that, with the initial maps can be put on a clipboard or some such device and kept close by so they are handy when needed. A little pen/pencil holder is helpful; when the airlines got the then high-tech Boeing 767s, despite all the gee-whiz stuff, an exciting cockpit improvement was a set of pen/pencil holders. Instrument charts should be treated the same way, and a clever pilot will have a clip or some such gadget on the control column where the plate can be displayed for reference while making an approach. It should be lighted. Going into big and busy airports, there can sometimes be five or so charts covering the arrival through the approach and then taxiing to parking. At faraway places, especially overseas, where there are occasionally different procedures, a pad of sticky notes can be helpful. Of course, today’s electronically displayed charts are a true blessing after years of paper charts; but only if we can select them with minimal “heads-inside” diversion. The charts that we fly with, their course lines, frequency boxes, ball-notes, little information boxes with an arrow pointing to where it applies miles away are

confusing and often difficult to read and interpret. There have been serious mistakes made because of the way in which things are sometimes presented. The papers we work from are a built-in hazard and should be treated as such. It is necessary to study routes and terminals in advance, so you don’t have to do it in the cockpit under poor light while bouncing around and trying to fly the airplane. One way to catch errors that may result in using the wrong facility is to always identify what’s been selected before using it. Every time we use a navigational aid that has Morse code identification—such as a VOR or ILS—it should be identified—period! It’s a good plan to have a systematic and consistent procedure for studying instrument approach plates, or the procedure as displayed on any appropriate electronic displays, before flying the actual approach. We’ll talk more about this in Chapter 19: Landing in Bad Weather . With bigger airports, we find standard procedures for departures known as Departure Procedures (DP ), which were called, and some folks still do call, Standard Instrument Departures (SIDs ), their concept being consistent ATC departure paths, crossing altitudes, and speeds for high-traffic density airports. They create another chart that must be consulted before takeoff. It is important not to be rushed into taking off until one understands what the SID/DP says and has it firmly implanted in one’s mind. Similar in concept to DPs are Standard Terminal Arrival Routes (STAR ), except, of course, the STAR routes are for arrivals and again show the proper routing, altitudes, and speeds. Combined with STARs are profile descents for high-flying aircraft. Sometimes profile descents have their own special charts, too. When DPs and STARs are presented and used electronically, like everything else we load and fly electronically, we must verify they are correct as loaded into our electronics. This comes up again in Chapter 14 on flying with technically advanced aircraft. All these are important, because there is lots of “fine print” that makes it easy to miss some ambiguously worded instruction. It’s best to study these documents carefully in advance, on the ground, and at leisure, and then to refresh one’s memory before starting takeoff or descent, preferably in a relaxed, cruise portion of the flight for the later. Rather than hunting all over the chart when busy in flight, felt marking pens to overlay routes, altitudes, or any other important bits of information are a big help. Yellow is a popular color, but orange can work better at night. If you have red cockpit lighting, red markings disappear. When I (ROB) started doing this I’d get kidded that the map would eventually be all yellow. Close, but it seemed to work and looked cool.

Go Fast Slowly

There’s a great tendency at busy airports for clearances to be delivered too fast and followed by a rushed, “Line-up and Wait; be ready for an immediate takeoff !” It comes in fire-hose fashion and tends to make people take off, half understanding how and where to go when in the air. The answer is simple: to heck with the tower. Sit there and study the clearance. If you don’t get it, ask for a repeat. Then, when certain, ask for takeoff clearance. It’s better to delay the takeoff than to rush off half-informed. Admittedly, at a busy airport if we’re not ready we’ll possibly be shuffled out of the takeoff order, instead of holding up everyone behind us, but if that’s necessary, so be it. In the cockpit, we need a place to write clearances and various things that pop up during the flight. We want to copy weather and clearance changes, keep track of fuel used, and write down a lot of other things. We need a clipboard or knee pads strapped on, handy for the job, although today some carry electronic devices tracking course, showing weather and so on, on these knee pads or specialized mounts. A computer (electronic or manual “whiz-wheel”) and plotter, big enough to see and handy at all times, are also indispensable pieces of equipment. When we have electronic cockpits, we can sometimes get weather via data link, but eventually it gets updated with new images and information, so unless you have a super memory, writing things down as to following weather trends, changing METARS for comparison to forecasts, and so forth, is sensible. Despite electronic cockpits, there still is a place for paper and pen.

Good Housekeeping All this is part of instrument flying, and keeping a neat, organized cockpit makes instrument flying much easier. More important is the fact that a disorganized cockpit makes instrument and weather flying much more difficult and increases the possibility of serious mistakes. In setting up a cockpit, it is important to keep it consistent, functional, and organized. Everyone develops quirks that work for them, from clipboards with helpful reminders or checklists taped on them, to where we position charts, writing gadgets, sunglasses, headset, and device wires hopefully in some sort of neat, non-conflicting and organized position. Not only does this keep us from forgetting things, it makes flight preparation and function run smoother and more quickly without being rushed, both on the ground and in flight. This was never better displayed than with pilots rushing through frantic changes of airplanes and gates during airline hub-and-spoke operations. The beginning of cockpit preparation—often referred to as “making our nest”—came from the infamous “black-bag” flight kits disgorging the manuals, maps, sunglasses, headsets, writing pads, breath mints, special fly’n-hats, clipboards festooned with personal checklists, and other personal items. There was even a

time we had our own oxygen mask face-pieces, which clipped into the system’s headbands. Occasionally strings or rubber bands were connected between various items to keep from forgetting them when the flight was over. After about five minutes of flailing around, an unruffled calm began to settle over methodical preflight of controls, buttons and knobs, electronic voices of tested warnings, then the efficient process of monotone procedure review, checklist reading, and radio banter. Suddenly, all was ready, and everyone was sitting there as if nothing had happened, just waiting for the pushback clearance, with all tasks thoroughly completed and understood. A good pilot or flight crew knows the responsibility of proper preparation and restraint over the whole operation; and that they own the parking brake. Fortunately, in general aviation, we have less of this issue, unless we have an impatient boss or fly by the clock instead of common sense. So once organized and underway, a copilot can help reduce an instrument flight’s workload; but even if we don’t have an official copilot (that is, a pilot with ratings), we can often train a nonflying person to look things up and sometimes even to handle the radio. This is best done by sessions at home, with the pilot going over the airways, approach, and navigation charts with the nonpilot and explaining what they are, how certain ones are needed in flight, how to find them, how to add mileage, how to fold charts for pilot convenience and point to where they are, how to dig out frequencies, and many other small but useful duties. This can expand to learning the use of a computer for speeds and fuel calculations, to basic radio work. However, when it comes to navigation, and especially in today’s world of programmed navigation systems, the nonflying person, whether a pilot or well-trained non-pilot, should always check with the pilot flying before changing things, rather than surprising us with sudden route modifications, erasing flight paths we’re flying, and so on. A little training of this type may turn a willing spouse, child, or friend from a bored or nervous passenger into a useful, interested, and relaxed crew member, even if they don’t know how to fly. Unless we have some form of autopilot, a copilot during serious instrument flight in a very busy ATC environment is arguably a necessity—not required by regulation, but without a doubt, hand-flying instruments without a copilot is a very tough job. Flying a light aircraft in serious weather, on instruments and alone, is much more difficult than flying an airliner with a crew. When smaller jets were approved for single-pilot operation, an operational autopilot and boom microphone, among other things, were required equipment. This is a smart choice with any aircraft, automated or not, as is the requirement to advising ATC if the autopilot or other technology we require has failed. Then we can decide if that day’s weather and ATC environment is workable for us, diverting if not.

An Extra Hand

Without a helper, the workload gets pretty heavy. One way to reduce it is by using a boom mike. The wide use of intercoms and headsets, especially noise-reducing headsets on many general aviation aircraft, has automatically brought the boom mike into wide use—a fine advance. In the past, fumbling around to find the mike, getting it off the hook, holding it up and pushing the button, taking one hand out of use was all terribly primitive. With a boom mike and a button on the control wheel, one need only squeeze a finger to communicate. The other hand is free to write messages, adjust gadgets, fiddle with buttons and knobs on high-tech avionics, and do the many chores it may be called upon to do.

Navigation GPS is certainly the wave of the future, even with the times folks must use VORs, and the few ADFs that remain. It’s wise to remember, however, that all the good of GPS and advanced electronic navigation bring with them programming. While this interface is getting better all the time, as of this writing we still must respect that when one deals with this, added effort is necessary to be certain, by care and double-checking, that it has been programmed correctly. Serious errors have occurred because of programming errors, whether in new aircraft or more so our day-to-day programming of electronic navigation systems. This also applies to older, stand-alone navigation systems like non-FMS Inertial Reference Systems (IRS ) and GPS units. Also, remember that low-frequency aids, such as the mostly discontinued LORAN, (which in some ways was unfortunate), or even the good old ADF, can be subject to precipitation static in heavy snow, some rain, and in thunderstorms. The best defense is to be certain the installation is properly done and the airplane has been rigged with antistatic antenna, discharge wicks, and such to minimize “P” static, as it’s called. And realize that there may be occasional but infrequent periods of no reception because of static, regardless of the aircraft’s equipment. The new aids do such a remarkable job that we’re apt to expect them to do everything, but they do have limitations, and one should study the manuals, learn the equipment, and be certain to fly within their limitations and our own common sense. Today’s modern navigation aids have made this task easy. They also have a tendency to lull us into a euphoric state of thinking everything is fine. Unfortunately, we hear too many cases of people crashing into mountains, not knowing where they were and unaware of possible flight path dangers. As we said before, it is still the pilot’s responsibility to know where the airplane is, what kind of terrain it’s over, and the terrain’s height. Maps remain an important part of the cockpit gear; we have not reached the state where electronic gadgetry can be trusted 100 percent of the time. The picture of a pilot flying on autopilot, being guided by GPS and sitting back reading the newspaper or fiddling with nonflying

related issues, is a shocking one. Flying an aircraft should be a 100 percent job. Giving it any less attention is reckless.

Radar and Lightning Detection Systems With all the computerized weather information of today, it’s pretty loose to consider flirting with thunderstorms without either NEXRAD, airborne radar, and/or lightning detection equipment. We get into this later, in Chapter 15 on thunderstorms.

9 Temperature, an Important Part of Weather Flying Temperature is closely related to many things we do with airplanes. It affects performance in takeoff, climb, cruise, and landing. It’s important. Air is the thing we use to make our airplane fly. How much or how little of the air that is available to our airplane relates to the number of molecules. The amount of air striking the wing is a function of speed and of the number of air molecules present. If cold, the molecules are packed closely together, and we say the air is dense. If it’s hot, there are fewer molecules per cubic foot, and the air is less dense. We sometimes say it’s “thin.” If the air is more dense, the better our peak performance. In dense air, engines put out more power; the wing has more lift. When the air gets hot and thin, it’s all reversed, and performance suffers.

Temperature and Density There’s another way of looking at it. At sea level, the air has a certain density, but at altitude, the density is less. We know how this affects performance. When we take off and start climbing, our rate of climb is, say, 1,000 feet per minute. As we climb, the rate decreases until reaching the airplane’s absolute ceiling, where there isn’t any rate of climb. Why did the airplane stop climbing? It’s simple: it ran out of air. The air wasn’t dense enough to feed the engine, and keep its power, so it couldn’t push or pull the wings fast enough to fly in the high and/or hot, less dense air. The airplane’s performance is limited by thrust, or lack of it. If there isn’t enough push or pull, the airplane stops climbing. An unwary pilot may keep pulling the nose up, trying to eke out a higher altitude or stay at a marginal one and get to an angle of attack pretty near stall—and that’s a fragile situation! So without air, an engine doesn’t do its job, wings don’t lift, and humans don’t live. This happens as we climb, because the air is less and less dense at higher and higher altitudes—not because of heat or cold, but because the atmospheric pressure is lower. The higher we climb, the less air there is above us pushing down and creating pressure. It’s always impressive to realize that half of the atmosphere is within the first 18,000 feet of altitude! At sea level, the atmospheric pressure is about 30 inches of mercury. At 18,000 feet, it’s about 15 inches of

mercury. Since hot air is less dense than cold air, hot air acts like air at high altitude, and cold air acts like air at lower altitude. What we’ve said is that air density and effective altitude are related. A sea-level airport on a hot day isn’t at sea level as far as our airplane’s performance is concerned. How high sea level can effectively become is sometimes a surprise. A sea-level airport on a day in summer, when the temperature is 38 degrees C (101 degrees F), has a density altitude of 3,000 feet! The sea-level performance of the airplane will have deteriorated about 20 percent. This figure will vary, especially with supercharged or turbocharged engines. In any case the airplane must not be overloaded; it must be flown carefully, and there must be enough runway for safe operation.

We Better Figure It Out We can easily figure density altitude on any good computer, whether it be an electronic one or a good old manual—and elegantly reliable—“whiz-wheel,” with a density–altitude computation. Density altitude is also broadcast on ASOS and AWOS. It’s worth a winter’s evening to tweak a computer and run out some make-believe situations, seeing how density altitudes can vary. Airplane manuals show performance at different altitudes, from takeoff through landing. Sometimes we’ll have to figure performance on tricky “chase charts,” which we’ll need to practice until they become second nature. The density altitudes we find on the computer can be compared with the airplane’s performance at that altitude to see what performance we can safely expect on hot summer days. In the computations, we must consider load—how heavy we are— and the advisability of reducing load by removing that camping equipment, “stuff” purchased, baggage, even a passenger or two. The airplane manual will show the performance versus load, temperature, altitude, and the lot. It’s important to study and refer to it carefully. Grasping the control wheel with an upward pull, sitting forward on the edge of the seat, dry of mouth and wishing the thing would climb and get over those trees is “too-late”; the manual reference should have come sometime before.

*New nomenclature for millibars is hectopascals (hPa ). However, upper air charts, etc., still employ millibars. You’ll hear hectopascals with altimeter settings, etc. † Note about tropopause: It is where the troposphere meets the stratosphere, which is also where the troposphere’s cooling with altitude ceases or even warms a bit. Above the tropopause, in the stratosphere, the temperature remains constant at −56.5°C, if at standard temperature and altitude as shown in the above table. There can be variations, because the tropopause height will vary widely.

How Hot, How High? If one flies out of high-altitude airports, 5,000 feet or more, with hot temperatures, it’s not unusual to have a density altitude of over 8,000 feet! Some low-powered airplanes will hardly fly at that altitude, and even the best will have impressively reduced performance. Standard temperature at sea level is 15 degrees C (59 degrees F). That’s what all those manual figures are based on. The moment the temperature has gone one degree above 15 degrees C, the performance has started to deteriorate. Remember that on a warm summer day when taking off from a small country airport with trees to clear at the end of the runway! Only 10 degrees F, or a couple of degrees C, above standard can make an impressive difference, and if the wind is light, or almost calm, don’t shrug it off as unimportant then take off on any convenient runway. Be sure, after takeoff, that you will be climbing into a gradient wind that will be on your nose helping performance, not into a tailwind and its sagging shear affect. Avoid the doublejeopardy situation of poor performance from above-standard temperature and soggy airspeed struggling through shear. It is important to consider the lay of the land for the airport. If the wind is calm, or nearly so, with no wind shifts or gradient issues, taking off downhill and/or over low or no obstacles deserves serious consideration. Conversely, landing with similar wind situations, doing so uphill when length is tight, is also an important consideration.

Engines Don’t Like It Hot Heat affects the engine’s running, too—piston or jet. It doesn’t put out as much power, because it is flying, in effect, at a “higher” altitude. Running a piston engine on the ground can excessively heat up heads and other engine parts. Tightly cowled engines need a lot of cooling airflow, and when we are sitting on the ground in hot weather, the engine isn’t getting the flow it may need. We should keep ground-running to a minimum, and if we must sit there with the engine running, be certain our nose is headed into the wind to gather all the air possible. Engine vapor locks can occur quite easily in hot weather, but most modern engine systems are designed to prevent these issues. However, if fuel boost pumps are required to be on for takeoff, it’s worse to forget them on hot days, when vapor locks could occur. If we use that checklist, this will not be a problem. All this suggests that cold days are wonderful. They are, for airplane and engine performance. The airplane leaps off the ground and it climbs like a homesick angel; it’s one compensation for shivering in a cold-soaked cockpit. One of cold weather’s hazards in relation to air density is its effect on the altimeter. In very cold air, the altimeter will read higher than the airplane’s actual altitude.

For example, flying at 10,000 feet with a temperature of minus 32 degrees C (minus 25 degrees F), which is 27 degrees C (49 degrees F) below standard, if the altimeter setting was furnished by a sea-level station, the altimeter will say 10,000 feet, but our actual altitude will only be 9,000 feet! So if we were poking around mountains counting on 1,000-foot clearance, we might not have it. Imagine a low approach to a sea-level airport with a very substandard temperature of minus 26 degrees C (minus 15 degrees F), such as one can get in colder climates, or more insidious, an unusually cold winter in a place where folks normally are not familiar with these problems. When our altimeter says 300 feet, we’d only be at 258 feet . It’s seemingly not a big difference, but big enough when you’re making an approach to a 300-foot-minimum airport. If we are established on a 3.00° glideslope angle, at 70 knots (ground speed) for a singleengine aircraft, we’re losing about 6 feet per second. That’s not a lot of time to delay decisions. (A light twin is around 10 feet per second and a jet about 12 feet per second.) A good rule to remember is that for every 11 degrees C (20 degrees F) the temperature varies from standard, there is a 4 percent lower error in the altitude compared with that indicated on the altimeter (lower temperature, lower altitude). So cold temperatures are fun to fly in, but they can give us erroneous altitude information, which can be disastrous. What this all says is that temperature, like wind, is one of the elements that a good pilot must become aware of, constantly checking what the current temperature is and how it’s going to affect the flight.

10 Some Psychology of Weather Flying Before getting into weather flying, we should talk about emotions. Basically, airplanes get us into places and situations that humans weren’t designed for. The inside of a thunderstorm, for example, where the airplane is battered by turbulence, where there are deafening, rapid-fire staccato noises caused by heavy rain, and sometimes hail beating on the airplane and our nerves. Lightning flashes, thunder is heard, and now and then a flash of lightning leaves an odor like the burning insulation of an electric wire that spooks our inner senses. In clouds, with ice collecting on the airplane and a very low ceiling at our destination, we can feel pretty lonely. With a little imagination, a pilot may wonder if that cozy world is still down there at all. At times, flying weather requires a firm grip on one’s emotions. Emotions have to be subdued by realizing that to lick weather, one needs logical, step-bystep thinking and intelligent use of equipment. Wishing will not make a successful descent through the clouds and landing at the airport. A good job of flying will. Sometimes a pilot’s firm grip on emotions means forcing oneself to control a nervous stomach, dry mouth and shaking hand. It might be fighting to overcome staring at instruments with nothing much registering in our minds; instead we force a hyper focus to cognizant control of the aircraft, and then work back out into the broader range of managing the flight. It’s like rebooting ourselves without turning off our brain’s computer. This isn’t always easy, and anyone who says they’ve never been scared flying in weather either isn’t telling the truth or hasn’t been there! What we have to do is control any tendency to panic, instead keeping everything under control. One can be anything from slightly to completely scared and still think—and think we must. A difficult factor is that sometimes in flying we can be nervous or scared for a long period of time. We may sit on instruments a number of hours with everything under us below landing limits and our destination on the ragged edge as well. This type of operation is known as “sweating it out,” and never was a more perfect description thought of for anything.

Self-Discipline When everything inside us is scared, we have to work harder to do a good precise job of flying, thinking rationally all the time. In this situation, a pilot must do the

utmost to be relaxed. Being relaxed creates better flying and better thinking, which reduces fatigue. So even if hell’s fire and brimstone are all around, we must keep reminding ourselves to sit back comfortably, relax those white knuckles on the control wheel, and think! It isn’t easy, but it’s possible; and working on it, forcing oneself, and practicing make it possible. Surprisingly enough, this effort can develop a control over our emotions that favorably affects the nonflying part of our lives, from driving automobiles with their dangers to personal problems of finance or the heart. There’s a natural tendency for fright to speed things up. If a person is in a jam in the air, and especially on a VFR flight when we have not heeded sense to stay out of a weather squeeze, the basic human desire is to be back on terra firma. If panic takes over, there may follow a desperate, too-fast attempt to get on the ground almost any way that seems possible. This is dangerous, with a doomful prognosis. This is when people try to go lower when they should be going higher; it’s when they try to auger down through a small hole in the clouds below, too low from the ground. It’s when they wait too late, as the sky lowers and the ground rises, at last realizing it’s time to land somewhere before hitting the ground; nevertheless, they try to hasten a landing in a field without looking it over carefully, nor have they checked for trees, wires, and what have you around it. What we must do when fright takes over and panic begins to spread is get up where we are clear of all obstructions. We stay where it’s safe, even in a circle, and then, in both cases, take time to think the situation through carefully, get settled down, and after that act calmly and precisely. We should talk a bit about asking for help, and while it isn’t a part of the emotions from weather flying it is related to being in trouble. A pilot shouldn’t be bashful or reluctant to say he or she is in trouble or getting close to it. The radio is there to aid pilots. There’s plenty of help around, and a good, clear heads-up will bring it running. Say what’s wrong, where you are, what’s needed most. Use the frequency currently being used or the emergency frequency, 121.5 MHz. The calmer one can be while doing this, the easier it will be for someone to help. On the other side, if we get into imminent trouble, the first thing not to do is talk on the radio—we think and fly the airplane. Unlike movies, an airplane in a traumatic state does not switch control from flight controls to the microphone. It is well to remember that asking for help should be in the category of last resort and not a crutch used routinely to help fly weather. Proactive weather flying and communications means calling Flight Watch, the FSS, or maybe talking with ATC for flight-following and weather input, when they have time. ATC is not there primarily to get you through thunderstorms or other bad weather. Their job is traffic separation, and all other services take second place except, of course, in emergencies. However, emergencies should be emergencies, and not thought of as “routine” help for ill-planned flights. There’s another place we need discipline, and that’s when our modern world

of electronic instrumentation and/or autopilots start doing things they shouldn’t, especially close to the ground. We need the discipline to bring our high-tech brain, and the unguided missile we’re flying in, back to the basics, either through expeditious and skillful knowledge of our instrumentation and autopilot, or if that doesn’t immediately work, through skillful hand-flying. Then, once settled at safe altitude and attitude, we should methodically bring our automation back into play. This is repeated in later chapters, and where it may seem we’re over doing this situation, real-world incidents say we’re not.

Think, for Real People rarely get into the situations we have been talking about, and weather flying isn’t a desperate thing at all. One reason people do get into trouble is that they don’t do enough logical thinking in advance. The preflight analysis of weather, the decision to go or not, the planning of fuel, and the cold decision of whether the airplane and pilot are adequate must be done logically and objectively. Do not take on weather beyond the airplane’s capability. A Cessna 172 cannot fly weather of the magnitude a well-equipped high-performance single-or twin-engine airplane can, and this continues on up the ladder of aircraft size and performance. Simply and briefly, we need range, enough power to climb fast and high in certain conditions, deicing/anti-icing equipment, and radar or at least lightning detection for thunderstorms, as well as instruments, avionics, and autopilot to relieve the multiple workloads that weather and the ATC system demands. With respect to how we think, hunches, assumptions, and “that’s close enoughs” don’t have much place here—with the exception that negative ones cannot hurt, such as, “I’ve got a hunch that place will fold up, so I’m going to take more fuel.” Actually, that probably wasn’t a hunch, but a judgment made after studying the weather, and experience we’ve gained over time, creating subconscious sense. But irrational optimism, like thinking, “It’s going to be okay,” on the basis of a keen desire to get where one wants to go, is taboo in this business. If a pilot uses logical thought processes and keeps emotions under control, it will become possible to handle tough problems with composure. Being prepared with proper briefing, keeping up with weather’s changes, knowing equipment, and feeling competent with practiced flying allows one to find that desperate situations seldom seem to occur.

11 Turbulence and Flying It Turbulence comes in all sizes, from a little choppiness to big, hard clouts. It affects us near the ground and up high where jets fly; even U-2s at 70,000 feet find turbulence. Unfortunately, we cannot see the motions of air, and there is still doubt about how, exactly, the air moves when it’s disturbed. Flying gliders close to mountains has taught us much about the interaction between wind and mountains that creates turbulence, sometimes very nasty turbulence. And working gliders in these mountainous areas has also taught us about waves, both how to avoid or benefit from their fascinating action. Flying over the sea, too, one cannot look down on the endless waves, whitecaps, and swells without thinking that the ocean below probably isn’t much different from the one we fly in. They just have different densities. A wave comes toward the shore and hits a line of rocks. The water sprays and tumbles over the rocks, creating a confusion of wild water. Make the rocks a mountain and the water fast-moving air (wind), then the similarity becomes obvious. Is this much different from wind hitting the trees on the approach end of a runway, being pushed up then broken apart, descending in a confused manner toward the ground downwind of the trees? No, we don’t think it is. Way up at 35,000 feet, couldn’t turbulence be a moving mass of air in waves? The wave breaks and, if we could see it, might look like an ocean wave, the kind surfers ride. All this comparison may be amusing to think about, but how does it help? It helps in visualization. Our wave breaking over rocks, which would give us a wild time riding in a boat, can be much like the wind coming against obstructions; it will be disorganized, so our airplane will roll, yaw, and pitch, as well as balloon upward, then descend. We must be prepared to combat this.

Some basic—but important—views of wind effects around an airport. Visualize water rushing down a streambed and then flowing over smooth, downward-sloping rocks. It follows the contour of the rock bed. A runway perched up high, with the ground sloping downward, away from the approach end, is the same thing. Coming in to land, we fly over the sloping area, where the wind flows down the slope, and we sink as we fly into this downward-flowing air.

A marginally low airspeed, plus aiming to land short, may suddenly find us touching down before the runway with a good chance of leaving the landing gear back on the slope as we slide on our belly along the runway. A good pilot visualizes the air motion around an airport, a mountain, or any obstruction near the flight path. As we fly by an airport on downwind leg, we should have in mind the wind direction, velocity, and gustiness. Then, with a crafty eye, we look at the obstructions and visualize how the air is moving over them and how it will affect our airplane. We should be prepared for choppy air, a downdraft, or sometimes an updraft that will make us balloon when we don’t want to. Be aware that the wind direction is not always directly down a runway, but often across it to some degree or other. If obstructions, such as trees or buildings are to the side of the approach path to the runway, then any cross-component of the wind will cause spillage over those obstructions, making the approach a turbulent flight, frequently with strong downdrafts. Mountains can cause up and downdrafts whose effects can be felt over considerable distance, and one should look at the terrain for many miles in all directions and try to visualize its influence. A good example of this was the two of us (RNB & ROB) taking off from Honolulu in a Cessna 402 for Tarawa in the Gilbert Islands, 2,400 miles southwest over the Pacific Ocean. It was a ferry flight, and we were overloaded with extra fuel. Once in the air, after a long takeoff run, we made a right turn and headed out to sea. Our climb was very poor, but after flying away from the island, it suddenly increased to the normal rate for the load we had. Putting it all together, we realized the ground slopes up to about 2,800 feet 6 miles northeast of the Honolulu airport. The pleasant northeast trades were flowing down the slope of this Koolau Range, causing a large area of settling air that we were trying to climb in. It kept us down until we flew out of it 8 to 10 miles from the mountains, after an interestingly low tour of the ocean.

Kinds of Turbulence Turbulence can be categorized according to its location. These are the places and areas pilots find turbulence: • near the ground, in those obstructions we talked about or around hilly and mountainous terrain; • in the convective layer of the atmosphere or, in simpler words, in the haze below the inversion; • in clouds, of course, and the more unstable the cloud, the rougher; • in clear air at higher altitudes. The last one, in clear air at higher altitudes, is not to be confused with the

turbulence in the convective level. It is turbulence in clear air well above the convective level, generally in connection with a jet stream. But there are other things that may cause it, and we’ll go into them later.

How We Fly Turbulence We should talk about the ways we fly an airplane in turbulence. Basically, it’s a matter of not fighting, but rather letting the airplane have its way with the little displacements it wants to make. We don’t sit there and madly fight the stick or wheel. This, of course, has its limits, and there comes a time when we say, “Whoa, baby, you’ve gone far enough.” Then we move controls and make the airplane come back where we want it. Because an airplane pitches, rolls, and yaws, we might look at turbulence from those aspects. Let’s start with pitch, the up and down movement of the nose. A gust will make the airplane’s nose change position. What we want to do is keep the nose where it should be, and that position is the place on the horizon, real or artificial, for the speed we are trimmed. We fly this attitude and keep the nose near that point on the horizon. If we take off, put on power or reduce it, this attitude will change, requiring us to retrim the aircraft. But these trim changes are small. In clear air on a calm day, we can see what positions the nose takes for different speeds and different power settings. What we want to avoid is large displacements of the airplane. One quickly learns that big power changes make big attitude changes. This is a clue, of course, that juggling power during turbulence in large amounts will result in big attitude changes, out of trim control forces, and general confusion in flying. We don’t want that. It’s best to know the speed one wants, trim for it, and then ride it out, keeping the nose very near this trimmed position. On that clear day mentioned above, one should try and memorize pitch settings, on the artificial horizon, versus power settings and trim for everything, from best turbulence penetration speed to climb after takeoff. They will vary with load and altitude, but will be valuable as something to quickly grab when needed —at least as a starter. This knowledge is also useful in the event of airspeed indicator failure, iced-up pitot, taped-over static port, or a mechanical failure. Altitude will vary. If it’s very rough, and you are worried about the structure, let it vary! Otherwise, make the smallest possible power adjustments and keep the flying technique as simple as possible. Roll and yaw are mixed together to different degrees in different airplanes. Push a rudder pedal and the airplane yaws; as it yaws, it will begin to bank, sloppily, but it will. In a swept-wing jet, this tendency is very strong. Push the rudder and immediately it starts to bank, too. Bank the airplane, on the other hand, without moving the rudder and its nose will eventually start to yaw around.

Another thing that happens with bank is that the nose goes down. Bank the airplane, and the nose starts down; unbank it, and the nose rises. The important time, however, is when the nose goes down. That’s how spiral dives begin if a pilot is on instruments in rough air and is not experienced. The airplane banks, and the nose wants to go down. If the pilot pulls back without doing anything about correcting the bank, the bank steepens, the nose drops more, and the speed goes up. It’s a spiral dive off and running! It happens very fast. Many airplanes in this condition will, when improperly flown or not corrected, reach redline airspeed in something like five seconds or less! So, keep the wings level! It’s simple, really, to keep the wings level and keep the nose where it should be on the horizon. Do it in a relaxed way with easy pushes and pulls, not jerks and shoves.

Convective-Layer Turbulence Now let’s talk about turbulence in the convective layer, the stuff below the haze level. We’ll say that today’s a day for it. A front passed yesterday, and from our study window, across the rolling country, the visibility is good in a brisk northwest wind. There are small, widely scattered cumulus—CU—drifting rather fast across the sky. Just a glance at all this says it will be rough from takeoff until we get on top of the CU—probably only about 5,000 to 6,000 feet, because it’s November, and in colder weather the tops are lower than in summer. There are mountains in our country with farms, fields, and woods. As we takeoff and climb, it will be rough. Turbulence will start pushing us sideways as soon as we leave the ground, jolting and jarring. That will last until we reach 800 to 1,000 feet, because of the turbulence from the unstable air being joined by the turbulence of that strongish wind bouncing over the hills, trees, and fields. So there are two types of turbulence: orographic turbulence caused by terrain, and instability turbulence within the air mass. Above 1,000 feet it will still be rough, quite rough, but some of the small, jiggling, jolting, fox-terrier kind of action will be gone as we get up out of the orographic influence. We reach the level of the cumulus, climb up above that, and suddenly, like flipping a switch, it is smooth. The haze is below us, and at our level, visibility is truly unlimited. It’s the place to be. But let’s go back and wallow around in the rough air below. How rough it is depends on the air’s instability and is the strength of the wind. The fresher the air mass (that is, the first day or two behind a front), the stronger the turbulence. The air is colder than the ground, which heats it and sends the air upward in fastclimbing thermals. These are the days glider pilots become giddy. The sky is full of lift, and they make records and go long distances.

But in an airplane, each thermal we go through is a bump. Some of them are pretty strong bumps. Out West it’s not uncommon to fly a glider in thermals going up more than 1,200 feet per minute. Hit that column of rising air at airplane cruising speed, and it’s a good jolt. With well developed, wider thermals, bumps become surges, at times requiring us to pull the power back as we work to keep the airplane level and our speed approaches limits. Conversely, coming out of the thermal, there is sink and the process reverses. If we don’t mind pounding around below the cumulus, we can save fuel and maybe increase the cruise speed by picking a path under cumulus, especially when they line up in what are called cloud streets. Now we’re flying with that efficiency a good sailplane pilot knows. Of course, not all days of good thermals have cumulus, because the air mass is too dry. Then, as we say in soaring, finding thermals is more like walking through a forest blind-folded; well, not totally, because we can look at terrain as a catalyst to lift, so we can weave our course a little, picking potential areas of lift.

This beautiful cumulus-filled sky is a perfect West Texas summer’s soaring sky. The cumulus form from thermals, which begin having clout later morning and may not end until the sun is quite low in late day. If the atmosphere is too dry, the thermals are still there but no cumulus to mark them. Flying through these conditions we will find turbulent jabs and jolts, transitioning to a dramatic surge in thermal cores, their lift sometimes over 1000 feet per minute, with similar sink once out of the thermals; in such conditions, one should consider flying slower airspeeds for turbulence. In such arid country cloud bases can easily reach 15,000 – 18,000 feet! To find smooth air we fly above these CU, but we’ll need an airplane with high-altitude performance and oxygen or pressurization. The other trick is to fly early or late in the day. (PAUL BRADY/AOL INC. USED WITH PERMISSION)

It’s Rougher Than You Think I’ve often thought, while bouncing along in the convective layer, that if I were on instruments near a thunderstorm, hitting bumps this hard and certainly no stronger, I’d be quite concerned. We’d have the airplane slowed down and be using our best turbulence flying technique. But because it’s clear and sunny, we don’t think much about it. Sometimes we should, because the airplane’s structure is taking a beating. A special time to consider this turbulence is during descent. We often see pilots push the nose down for descent, letting the airspeed increase until the airspeed needle is tickling the red line. This usually starts above the turbulence, where it’s smooth, and the airplane is making impressive time. Then they descend through the inversion into the convective layer and suddenly it’s like hitting a brick wall, with really solid bumps. The combination of very high speed and the strong jolts are certainly putting a heavy load on the structure. An alert pilot will reduce airspeed before whamming into the roughness below the haze level and then, after the intensity has been felt, make decisions as to the best speed for the descent, considering comfort and the airplane’s structural integrity. High performance aircraft have turbulence penetration speeds, while other aircraft, such as lighter general aviation designs, maneuvering speed.

Fly above this kind of cloud. Like the image above, beneath these cumulus it will

be rough and uncomfortable, while on top the air will be clear, smooth, and cool. In less arid climates we may find tops around 5,000 to 10,000 feet. (NOAA PHOTO) There’s little reason to stay down in the convective layer and bounce around if you can top it. In the East this is generally fairly easy, because the top of the layer isn’t much over 7,000 in winter and 10,000 in summer. In the far West, as pointed out in the figure on the previous page, it’s another matter. Because of the high ground and strong heating from the arid land, the haze level will often be above 15,000 feet. Then you need oxygen or pressurization. Flying in the constantly bouncing air is fatiguing, and it’s uncomfortable for passengers. The bouncing kind of wears on the aircraft structure, too. This isn’t a serious point, unless we really push the old bird, but it is worth considering.

Dust Devils On windy, rough days, especially in the West, where there is less grass and more dirt, dust devils form. These look like miniature tornadoes that work across the countryside, kicking up dust and dirt in a swirling cloud. They are easy to avoid, and it’s a good idea to do so. On landing, one can get roughed up near the ground, settle drastically, or flat lose the airplane, hooking a wing as one is tossed around. The action feels much like prop wash or jet vortex; it has that uncontrollable feeling. Even after one is on the ground, the dust devil can lift a wing or flip an airplane over. Big dust devils are obvious, but smaller ones may only look like gossamer, funnel-shaped ghosts skittering along. If we aren’t looking carefully, we might fly into it. These things are not always made of dust; we’ve seen them as clumps of swirling grass from cut fields, among other things, and one day while flying a good thermal in a sailplane, these clumps of hay wafted by the canopy at 6,000 feet. When dust devils are forming, it’s important to have airplanes on the ground well tied down, again because a dust devil can easily turn over a parked airplane.

Turbulence Near Mountains and Ridges Flying during strong wind conditions in mountainous areas, as well as ridges, particularly when the air is unstable, can result in some very rough rides. The windward side of a these ranges will have predominantly rising air. It will not be consistent, but rather choppy and gusty. The gustiness will show itself in great ballooning climbs that will make you feel you’d like to reduce power, followed by sinking feelings as the lifting air diminishes. Often this variation will simply be the result of flying from one contour to another. Mountain ranges and ridge lines

are rarely ruler straight. They have cuts, twists, and pockets, so the wind hits the ridges at different angles. Also, the slope angle will differ which further complicates matters. All these irregularities create variations in the effect of the winds over the mountains and ridges. Glider pilots who have done a lot of ridge soaring learn this, and an experienced one can often look along a ridge and tell what kind of lift and turbulence will be found and where. However, they also learn there can be surprises down low that can be quick and dramatic. Sailplane pilots who know and respect the eastern United States’ Allegheny and adjoining ridge systems have set records in excess of 1,000 miles. These are dawn to dusk flights, flying at low level and high speeds, paralleling the ridges in turbulent lift from strong, northwest winds! On the downwind side (lee side) of a mountain or ridge line, the air will mostly be going down. It will be chopped up, spilling, and rough. The place to fly is well away from the side of the ridge or mountain. In unstable air, ridges and mountains—especially the upwind and sunny sides—will produce thermals, which up higher might be rising shafts of air, but down low are often torn and inconsistent bubbles that add to the confusion of turbulence. In powered aircraft, we don’t always fly along mountains and ridges, but often cross them at right angles. Never approach the top of a ridge or mountain at a 90degree angle, make it 45 degrees, then if you’re having trouble getting over the top, it’s a shorter turn to get back to the valley. When we approach a ridge, it’s important to be aware of the wind. We’d like to know whether it’s a tailwind or a headwind, which varies closing speed, and of course how will it hit the ridge, creating rising or sinking air. Say we are flying low, 500 feet or so, above the ridge tops. With a tailwind, the airplane will theoretically climb as we approach each ridge. We are being “zoomed” by the air flowing up the slope. But when we pass the ridge and fly to the downwind side, the airplane will sink, and we’d better be prepared for it. Flying the other way, toward ridges into a headwind, has the opposite effect and is hazardous, because on approaching the ridge or mountain, we enter its downwind side. We could also call this the downslope side. We will sink, often below the mountaintop, and need power to keep us from getting too low and too slow. We shouldn’t just pull the nose up and let airspeed drop while trying to climb. Use lots of power and get up, but it’s usually best to turn away from the condition with sufficient airspeed and bank angle—control—running to the valley where we came from and reevaluate the situation. However, it is best never to fly low near mountains, especially the downwind side, particularly if the wind is strong. Again, we should be particularly careful flying toward them into a headwind, because of that sinking problem, which can put us in a dangerous position. Speaking specifically of mountains and larger ridge lines, never approach a mountain ridge from the downwind side, except with lots of altitude: a good recommendation is to use half the height of the mountain you’re crossing,

with 2,000 feet above the ridge or mountain a minimum. If it’s a big mountain and the wind is strong, this is a good start, but sometimes it’s just not the place to be, and finding a different route or maybe not going at all is the solution. A hazardous place to fly is between two ridges so closely spaced that downward-flowing air from one ridge is turning to climb up the next ridge. The air movements will be confused, and there will be lots of sink. The other issue here is that airflow over the top of the first ridge may strike the upwind side of the next ridge downwind, creating sinking air where you expect lift. Those are real micro-terrains and micro-weather issues, best heeded cautiously and left to those who are local and well experienced. Things can also get really strange when wind strikes a knoll or lone peak, the downwind side can be chaotic when split airflow rejoins. When flying along or across a mountain range, realize that the wind speed will increase where cuts and passes go through the range, because of venturi-like action, and the turbulence will become worse. The wind speed over the top of a mountain increases in much the same way that airflow increases over the curve of a wing. In the extreme, many of us have heard of Mount Washington in New Hampshire recording winds over 200 mph! It wasn’t the general wind going that fast, but rather the wind accelerated by the curve of the mountaintop. Almost any mountain will have this effect to some degree. Where the wind speed increases, there will be shear and turbulence on the top and the downwind side. Of course, what all this means is that we shouldn’t fly close to mountains when the wind is strong and the air unstable, especially on the downwind side. If you are close to a ridge or a mountain, never, never make a turn toward it. Always turn away. To really respect and learn about flying in mountains, we strongly recommend ridge and mountain flying in a glider, taking a mountain flying course, or at least perusing some writings on the subject…and the sailplane flying is fun, too.

Mountain Waves Mountains create another type of turbulence that extends above the convection level; it’s connected with mountain waves, sometimes called lee waves or standing waves . Fast-moving air—stronger winds in an air mass with a lower stable layer— hitting the side of a mountain causes waves in the air downstream of the mountain. They are like waves in a river behind a submerged rock. Waves in the sky sometimes extend to great heights. The front side of the wave is going up, and glider pilots like to hunt for this area and make altitude flights. The world altitude record in a glider, at this writing, is 50,721 feet off the Andes in Argentina, in a two-place sailplane flown by Steve Fossett and Einar Enevoldson. In the United

States, it is 49,009 feet by Bob Harris, off the southern half of the Sierra Nevada Mountains in California. From the 4,000-foot Green Mountains in Vermont, the state record exceeds 27,000 feet, and to the east over the White Mountains of New Hampshire, folks have exceeded 30,000 feet. We’ve felt wave influence at 7,500 feet from a 700-foot hill in eastern Pennsylvania, and admired world record distance flights from high-speed cruising parallel to mountain waves. Just about any ridge or mountain area will, with the right conditions, have waves that affect our flying. Even over the North Atlantic Ocean, on the east side of Greenland, with the correct air mass and wind conditions downwind from that island’s tall mountains, airliners have experienced severe turbulence from waves off the mountains on that dramatic land. Let’s visualize these waves. They form downwind from the mountain, not very far from, in fact almost over, the peak of the mountain. The waves repeat downwind with second, third, and fourth waves, and often lots more. The waves go up on one side and down on the other. We often discover them by noticing the airplane wanting to go up, then as we push the nose down to hold altitude, our airspeed increases without our adding power. We are in the up part of a wave. The air is generally glassy smooth. On the other side we get a smooth downflow. We have to pull the nose up and add power to hold altitude. This area is smooth, too, and maybe we feel a little choppiness transitioning between the lift and sink areas. So far, so good. However, under the wave, we find turbulence in an area called the rotor, where the wave air conflicts with the undisturbed normal air below and causes a tumbling, rolling, chopped-up, confused mess. It is rough, and how rough depends on the strength of the wind, the mountain, and how much of a wave there is. It can be very rough! In severe cases, this rotor has torn an airplane apart. It’s not a thing to fool with.

This shows two types of mountain turbulence: one is the tumbling air in the lee of

a mountain; the second is the rotor under a wave. The little cumulus on top of the rotor, a small shredded wisp-like cloud forming, is the cue telling where the air is very rough. The two types of turbulence can occur at the same time or separately when there is no wave action but lots of wind spilling over a mountain. How do we know it’s there? First, with strong wind flow across a mountain, especially after a front has passed, we can expect wave action. Looking up into the sky, we may see lenticular clouds. These are a characteristic sign of waves. They are long, slim, lens-shaped clouds, but the real key is that they do not move as normal clouds do. The reason for this is that the rising side of the wave cools air to its condensation temperature and forms the cloud. As the air starts down the backside of the wave, the pressure increases, the air gets warmer, and the cloud disappears. Because the mountain doesn’t move, neither does the wave and its lenticulars, except for minor variations due to atmospheric conditions. So the lenticular cloud forms and disappears on the wave, staying with it and not drifting along with the wind. If near the level of the mountaintops, it is very turbulent under lenticulars, or where they would be if the atmosphere is too dry for the lenticulars to form. When there is not enough moisture to form a lenticular cloud the wave is there, lurking invisibly. We should not be lulled into thinking there is no wave because there are no lenticulars! Any time the wind direction is across a mountain range or within an arc of about 70 degrees of perpendicular, the wind maintains this direction with height, and the velocity increases with height, you should be suspicious of wave action. In the valleys downwind of the mountains, the rotor often extends almost to the ground; the air near the ground is rough, and one can see clouds of dust swirling into the sky, if it’s a dry, dusty area. We’ve seen rotor off the seemingly gentle Green Mountains of Vermont that was almost down to the runway of our local airport. Descending to land, all the way through the landing pattern, was wildly turbulent. In more extremely mountainous areas, when it’s very windy it may be best to stay on the ground or avoid the area. Flying downwind of mountains, we want to be especially careful when the possibility of a wave exists. Sometimes we can get the combination of air-mass instability and wave-rotor action together, and it makes for a mighty interesting ride! Rotors can lie fairly high in the wave structure, but the most turbulent rotor will be found at the mountain level and below. If the mountain is 4,000 feet high, then the rotor will potentially be roughest from 4,000 feet down. To be on the safe side, we should again add 2,000 feet or so to the mountaintop altitude, in an attempt to avoid the worst part of the rotor. If you can see the rotor clouds, fly above them. For bigger mountains, it would be advisable to add extra altitude above the mountain height, say 5,000 feet more. But the best way is to avoid the area altogether.

Waves can be created by just about any size of a mountain, but as we’ve explained, they are not always visible. The rotors, however, will sometimes show themselves as little pieces of shredded cumulus-like cloud. There may be moisture in the lower levels that will support, or almost support, small cumulus, while there is not enough aloft to make a lenticular. So if you see cumulus on the downwind side of a mountain, generally not much higher than the mountain, and when you study them carefully you see a shredded, moving, turning-over appearance to the top side of the cloud, look out! That’s probably a rotor. Sometimes there will only be a few small, half-formed, gossamer-like wisps of cumulus that you almost “feel” rather than see, but if we’re watchful and see them, they can tell an important story. Those innocent-looking wisps may signal a very rough rotor. Any atmosphere like that downwind of a mountain should be cause for suspicion and, if one must fly through, it is time to prepare for flight in turbulence. Any flight downwind of a mountain, even a small ridge only 500 feet high, can have a nasty rotor if the wind is strong and the air unstable. Flight down low is not the thing to do. It’s no time or place to be circling a friend’s house or doing other foolish, low-level flying.

An idealized illustration of a mountain wave system and related atmospheric aspects. The wave is illustrated on the right, including classic placement of clouds related to waves that, depending on atmospheric conditions, may or may not form. Turbulence is also noted. Wave strengths, both of lift and sink, can vary from very little to thousands of feet per minute, as do variations of wave height, wavelength, number of downwind harmonics, and rotor turbulence level; these all depend on terrain height, shape, wind velocity, and atmospheric stability. On the left, we see

the relationship of temperature and dewpoint vs. cloud formation. Note the atmospheric stability at mountaintop height (temperature no longer decreasing with altitude). Far left is wind information, indicating similar direction and increasing velocity with altitude, as advantageous for wave formation. (COPYRIGHT: METPANEL OSTIV—THE INTERNATIONAL SCIENTIFIC AND TECHNICAL ORGANIZATION OF SOARING)

Beautiful lenticulars that tell a wave is working in the sky. They are smooth and peaceful looking, which can be the case, if our aircraft is snuggled in front of a lenticular’s upwind side, or there may be smooth sink on the downside of the wave, often more than an aircraft’s climb rate. However, getting to and from smooth areas usually means passing through significant turbulence, the worst being in the rotor below the wave system. Below the lenticulars pictured, we see innocent wisps of cumulus, but such is an indication of rotor turbulence and a rough ride. Depending on the wave system’s severity, this turbulence can threaten aircraft control, or worse, cause structural failure. (PHOTO BY ANDREW LAWRENCE) When getting in the lift of a wave, the air is smooth and might fool a pilot flying an aircraft with low power and no oxygen. It’s possible, but not likely if you are alert, to go up at a fierce rate to a high altitude where oxygen is needed. The way out of such lift is to turn downwind. But the aircraft would then get in the down part of the wave, which is also generally smooth. The descent rates may be high, more than one could overcome with the engine. Pulling the nose up and pouring on power is not the way to fight the downflow because it’s a sucker setup to get into mushing, stalled flight and not gain anything in the fight to combat the severe downflow. It would be best to keep up speed and fly fast downwind to get out of the wave condition. You might be going down fast while doing this, but the

combination of airplane high speed and the tailwind will get you out of the down current of air quickly. The pilot might go through a number of waves in the downwind dash, but that’s the fastest way possible. Waves do not have a very long wavelength in miles of distance, so it’s easy to turn and get out of the down and fly into the up part. With our 4,000-foot mountains here in Vermont, the wavelength is seldom over a few miles wide. It would be more for larger mountains, but still not a big distance. However, if there is strong wind at our altitude, the upwind push could take longer than we’d like. If you’re on a flight plan when encountering the down part of a wave and have trouble holding altitude, tell ATC the problem and that you’re turning around or can’t hold altitude. With marginal performance, never try to outclimb a wave’s downside by, as mentioned a bit ago, pulling the nose up with consequent speed loss; stall is never far away, unless the aircraft has enough power to climb and maintain good airspeed.

This iconic photo was taken by Sierra Nevada Mountain Wave pioneer Robert Symons in the early 1950s, looking south over the Owens Valley, on the east side of California’s Sierra Nevada Mountains near Bishop, California. It is over similar location to Gordon Boettger’s picture later in chapter, allowing a look at

the diversity of sky such conditions can produce. With the wind from the west (right to left), the clear air immediately east of the Sierra Nevadas is a significant downdraft through which even the most powerful aircraft would have issues and a wild ride. The dust (and smoke of local fires) is rising to the east (left) on combined rotor action lifting into strong wave lift; the region below the lower rotor clouds would be extremely turbulent. Worth noting is that this picture was taken from a WW II–era Lockheed P-38 twin-engine fighter, with both engines shut down, as Symons soared the P-38 to conserve fuel and wait for the surface winds to abate. This also may have been the day Symons made his famous soaring flight to 30,000 feet in the P-38, again with both engines shut down. In these types of conditions, pilots should avoid the entire area. (PHOTO BY ROBERT SYMONS AND COURTESY OF NATIONAL SOARING MUSEUM) A special situation is a single mountain that sticks up alone, like Mount Rainier in Washington State or Mount Fuji in Japan. Under strong wind conditions, the downwind side can have a combination of wave and vortex. The air spills over the top and around the sides, setting up a great whirlpool action downwind of the mountain that has severe turbulence. A Boeing 707 was torn apart in this condition near Mount Fuji. So it’s well to be very wary downwind of peaks that stand alone enough to create this situation; go around or pass any lone peak on the upwind side. Mountain waves are interesting, and playing with them in a sailplane is not only fascinating, but a good education for the airplane pilot. I’ve (RNB) landed many times in Milan, Italy, which is snuggled against the southern side of the Alps. Because of glider experience I was wave-conscious, studying and learning which conditions made the biggest waves in the area; generally, a quick look at the winds-aloft pattern told me if I had to be extra careful while descending into Milan, because of the possibility of wave penetration. Incidentally, the strongest waves there came with southwest winds from the direction of the French Alps. The point is that whether it’s Milan, the Rocky Mountains around Denver, Colorado, a little airport in Vermont, or countless other places, understanding terrain and wind can give us suspicion, if not a direct warning, that there is potential wave and all that comes with it.

Photo taken at about 11,000 feet, looking south, over Vermont’s Green Mountains. Wind right to left. Lenticulars above right are the primary wave, with the secondary to the left, and further cycles downwind off the picture. Below, stratocumulus is nearly overcast, but openings reflect airflow of each wave cycle’s downwind side, causing cloud dissipation, then reforms on the upward flow of the next wave cycle. These clouds can be at mountain height and are turbulent from rotor action—not a safe hole to “sneak” through. With enough moisture, it becomes totally overcast, causing us to be “trapped on top,” unless IFR capable. (PHOTO BY ROBERT O. BUCK) Wave action is something we can use to our advantage on cross-country flights if we’re paralleling mountain ranges, on top, when conditions are right. We feel periods of descending air, and our airspeed drops way off as we try to maintain attitude, then at other times, we seem to get a great boost and an increase in speed way over normal cruise. What happens is we’re flying in and out of waves, perhaps only mild ones. If we watch the top of the clouds, we’ll see undulations like swells on an ocean. Eyeballing these, we try to stay on the upwind side of a “swell,” where we’ll be in rising air and going fast. Moving our course around to fit these upflow areas may well be worth small detours and, as we said, the wavelengths aren’t very large in miles, so “fishing” upwind or downwind may quickly get you out of sinking air into lifting air and an airspeed boost. At times we may feel this condition in clear air when we cannot “see” the waves. If so, do that “fishing” by cutting up-or downwind at subtle angle to find “up” air. A great picture of this beautiful, high altitude world from a sailplane is seen in the figure on the next page.

A single peak has lots of disturbed air downwind caused by vortex around both sides and wave action over the top. A sign of vortex is an isolated oval or round lone lenticular downwind of the peak. If there wasn’t enough moisture to form a cloud, this condition would not be visible and one might fly into it unexpectedly. Lesson: stay away from downwind of lone peaks by many miles, going around the peak’s upwind side when winds are stronger than light.

A unique photo of difficult resolution; nevertheless an important story. Taken from about 35,000 feet, we’re over Greenland, looking down on a stratus deck of clouds. The white dots left, center, and lower right are higher snow-covered mountain peaks that have popped through the strato-cu deck of clouds. Wind from left to right, behind the peaks we see turbulence churning up the stratus clouds. At the same time, a wake spreads out on either side of the vortex center, very possibly causing the rippled wave-like undulations in the stratus. This shows the issues of vortex turbulence described in the text. (PHOTO BY ROBERT O. BUCK)

One day, when heading to Atlanta, Georgia from the Northeast, somewhere above 30,000 feet and nearing the Great Smoky Mountains, we popped out of what we thought was a deck of cirrus, quickly realizing it was a long, long lenticular, unusually high for waves in that neck of the woods. We felt a kind of gentle surge and soon reduced the power as our Mach built up. We settled at about Mach .84, and about 20 percent less fuel flow than normal. In a bit, we began to slow and felt a tiny bit of light choppiness. Telling ATC we wanted to head a little right off course, this put us upwind, back into the wave, as we would fly in a sailplane. Speed (Mach) picked up again, and we wandered on in lift for about 20 minutes, until south of Asheville, North Carolina, when ATC asked: “Hey, where you going, anyway?” The fun was over, and we turned back to the arrival route. Arriving in Atlanta, we had beaten time and fuel of the flightplane by a small but enjoyable bit. So, you can soar a 727—sort of. So this awareness of the air’s motion may save both fuel and time. It’s the stuff glider pilots work with and offers an exciting new concept and knowledge of the sky. It can also signify conditions to stay away from, depending on severity of conditions, both from wind, atmospheric stability and terrain considerations.

Lenticular clouds from above. Taken over the Owens Valley, east of the Sierra Nevada Mountains (lower left), looking north near over Lone Pine, California. Taken by soaring record pilot Gordon Boettger, the altitude is 26,000 feet, heading northwest (right to left) in a Glasflugel Kestrel sailplane. A very significant photo —Mr. Boettger is on the last portion of a multiple-leg, 1,400-mile U.S. national record flight, on May 31, 2011; the longest recorded sailplane flight in the northern hemisphere. With the wind from the left, or west, the smooth, strong high altitude lift lies on the upwind side of the lenticulars pictured, allowing highspeed running north and south along the wave. Commensurate sinking air is on the downwind side of the lenticulars. Below the clouds was extreme rotor turbulence and very high surface winds. Beautiful, yes, but not the place for most of us; instead, just a handful of highly experienced and locally familiar pilots. (PHOTO BY GORDON BOETTGER)

Turbulence Up High Sometimes turbulence that is not Clear Air Turbulence (CAT) is felt well above the convective layer, at 12,000 feet and up. This is generally light and associated with overrunning warm air preceding a warm front. It may also be there because of other air-mass changes. Often a look up will show altocumulus clouds. Big, High-Altitude Turbulence This sort of turbulence obviously relates to high altitude and high performance aircraft. Maybe a distant subject for the general aviation pilot grinding along way down low, but it still relates to the idea that all aircraft have performance limits. Also, with the increase of owner flown turboprops and jet aircraft, this realm is no longer just the world of professional aviation. We also give thought to more high performance, turbo-charged piston aircraft, with many sporting higher wing loadings and more sensitive aerodynamics towards better performance, to which high altitude flight can have an effect. So let’s talk about this CAT business—Clear Air Turbulence. This type of turbulence has been a bogeyman in high flying for some time; it’s been popular in the press and is often called the “airman’s enemy,” which it isn’t, but it does bear watching. Let’s look it over calmly. Most clear air turbulence is associated with the jet stream. The jet stream is a hose-like band of high-speed wind at high levels. It is one manifestation of constant movement in the atmosphere as the unequal temperatures of the earth— hot tropics and cold arctic—try to balance, with warm air working north and cold air south. There are also fronts high aloft that are part of this process. That is where jet streams wander, squeezed tight under the tropopause, with high winds and turbulence that influence flight, as well as the movement of surface weather. Because the temperature balance isn’t regular and neat, the jet stream doesn’t string out exactly east and west very often. Generally, it wanders in a serpentine fashion, so if we fly east or west, we may cross it a number of times. The jet stream is usually up in the high latitudes in summer, 60 degrees or so, and down south as far as 20 degrees in winter, but just to be difficult, it wanders north and south during both seasons. The hose-like part is the area of maximum winds that sometimes blow at 200 knots. There are also strong winds for hundreds of miles to the side of this special high-speed jet. The high-speed winds spread over a wider area to the right of the jet stream, looking downwind and in relation to the jet stream’s direction, than they do to the left. Where these high-speed winds rub against lower-speed winds, there is tumbling, turbulent air. Where air-mass densities change, as in a high-level front, it’s rough. Where a jet stream slams into slower-moving air ahead of it, it’s turbulent, too. Meteorologists can locate the jet stream rather accurately, but pinpointing

exactly where the turbulence will be has always been quite a challenge. They can tell you where turbulence will be in general terms, and turbulence forecasting is getting better, especially with today’s uplink–downlink systems in transport aircraft that constantly send wind, temperature, location, and turbulence data, among other things. After the two of us (RNB and ROB) have spent over 20,000 hours above 30,000 feet, we can be assured that sometimes it will be rough when they say it won’t and smooth when they say it’ll be rough. How rough is it? Moderate at times, perhaps severe by some people’s standards. Most of the time, the danger of the turbulence itself—CAT—is severe. It’s uncomfortable, at times very disturbing, and has hurt people in the aircraft that did not heed wearing a seatbelt. This brings up one of the toughest decisions of a pilot in command with an airplane carrying passengers—the seat belt sign. However, despite the trauma and discomfort, the aircraft comes through, so most of the time it isn’t anything that can’t be handled. It is possible, however, to get into trouble because of control problems. Up very high, the airplane has low thrust; it’s mushing along at a higher-than-normal angle of attack. It’s squirrely, as the expression goes, because its Dutch roll tendencies become more pronounced, then add some turbulence and it further antagonizes the process. “Dutch roll” is a coupled lateral (rolling) and yawing back-and-forth tendency of an aircraft; kind of a corkscrew fashion. It’s most pronounced with swept-wing aircraft, and especially those of earlier design, but is much improved in modern swept-wing designs; much due to better aerodynamics, less wing sweep and augmented flight controls. What helps stabilize a Dutch roll is a yaw damper, which makes automatic yaw (rudder) inputs to counteract the tendency. In some earlier jet designs, once above about 25,000 feet, a yaw damper was required, the aircraft possibly becoming uncontrollable with the yaw damper inoperative; hence, dual yaw dampers in some older jet aircraft. The industry has also realized yaw dampers make just about any aircraft’s stability better, which, as mentioned in previous chapter, is why we see this augmentation offered on even single-engine piston aircraft. The yaw damper is, in a small way, an early fly-by-wire concept in which electronic gadgetry makes flying easier. This is all part of the trend of these augmentations doing great things, making airplanes fly better than we can, allow more performance in design and they’ll be more in the future! But, we’ll still have to know how to fly because being electro-mechanical, these things can fail. In upper air turbulence, almost all of which is caused by shear, in extreme conditions airplanes can approach stall and may want to fall off on a wing. Where most aircraft flying such altitudes and conditions are on autopilots, the CAT has to be pretty wild to compromise autopilot operation. Never the less, in extreme situations older autopilot/aircraft combinations may begin excessive pitch excursions while trying to hold altitude, so we may benefit from disconnecting, and definitely any airspeed-hold mode, of the autopilot. Then, let the altitude float

a bit (and of course advising ATC of this condition) in trade for constant pitch control. However, hand-flying the airplane at high altitude—which is admittedly rare—takes careful flying to keep level and under control, especially in pitch, where a one-degree change can take us from level to hundreds of feet per minute climb or descent. Also, if one is flying an aircraft with both autopilot and autothrottles in excessive turbulence, disconnecting the autothrottle system prevents the surges, and pitch changes especially problematic with wing mounted engines, as the throttles/thrust levers chase airspeed. Usually these systems have better autopilots, which we can leave in full operation, the auto throttles being a separate entity. These considerations are especially valid at higher altitudes as the aircraft approaches stall or high Mach issues. These high altitude concerns are not a desperate situation if the pilot is on top of it and realizes that it may be necessary to give up some altitude to keep control. This nervous area is why it is best not to operate above any altitude where the airplane is close enough to stall, such that a 1.3- or 1.5-G bump might cause the airplane to exceed the stall angle of attack. In the past, this data was stored in performance books with graphs and tables relating weight and temperature to the aircraft’s performance, which we’d reference during flight. Today, with advanced aircraft, it lives in onboard computers—FMS systems—that read the aircraft and environmental data and then tell us maximum altitude for our current weight. Basically, a 1.3-G altitude is good for light turbulence, and anything more is 1.5G, which translates into a lower maximum altitude. If we’re flying higher than these altitude limits, exceeding turbulence maximums means the aircraft could exceed the critical angle of attack that threatens normal flight. The only problem is what really is light, moderate, or more turbulence, again, a pilot’s subjective decision, often made with only PIREPs from other aircraft as a resource. When fiddling with high altitudes, we’ve probably heard about the “coffin corner” where, between a very small envelope of speed—our only indication if we are without an angle of attack indicator—the aircraft is at either too high an angle of attack and risks stall or is going too fast, where the wing’s shockwave slides too far back on the wing, resulting in a kind of high-speed stall, from aerodynamic issues near the speed of sound. Often one wing is affected before the other, causing a wing to drop. We also need to remember a turn increases G loading, which increases the angle of attack, so we need to be gentle in turning at critical altitudes. Some of the old book data was based on 15° banks on the 1.3-G chart, which didn’t give much margin. In the early days of jet operation, when less was understood, such was cause of a few incidents and accidents from mostly stall excursions. The fortunate events included wild didoes followed by skilled handflying, along with the very rugged designs of those early jets, that saved the day. We can run into the above issues either by climbing higher than prudent for the aircraft’s capabilities or cruising in cooler air, then sliding into warmer tropopause air (we talk about the “trop” in a bit), where one can feel the airplane’s

mushiness. When struggling at these altitudes, the pitch angle is a bit higher, as the airplane claws for lift in the less dense air. Amazingly, even though this pitch difference is only a degree or so, an aware pilot can feel this “leaning back.” If the air gets the least bit choppy, an airplane can begin a slight wallow in that Dutch roll situation, even with a yaw damper. It’s not comfortable and a lousy place to be. Conversely, when you’re experiencing a positive dynamic, such as lifting air, and the airplane has the desire to “go”—it’s lighter in the seat and kind of like leaning forward a bit, which is really happening—that pitch attitude now a degree or so less, but we feel it, too. When flying an airplane with passengers potentially loose and wandering about, and you suddenly feel that pitch forward, and then a surge, like a gentle swell in a boat, it’s time to put that seat belt sign on, as usually in a moment the airplane will enter the staccato choppiness of turbulence. And so enters the terminology differences between “chop” and “turbulence,” which is study of criteria in pages of the AIM and other sources. Once in a while, it’s significant, and you only hope no one gets hurt. These events are not always in an area where there is warning of turbulence; a good lesson that we can’t fully predict the sky. Fortunately, however, modern aircraft and their improved aerodynamics have reduced quite a bit of these aerodynamically sensitive issues. But again, airplanes still fly by the same laws, and still have their limits, so the basic concepts should not be pushed aside as passé. So we heed the formula in flying CAT, which is to fly the recommended turbulent speeds and procedures, flying as one would in any turbulence, by attitude, with wings level and pitch and power changes at a minimum. Doing all these things will make CAT a nuisance and not a disaster.

Where Is It? Despite the difficulty in forecasting CAT, there are some cues the pilot can watch for to tell where CAT may be. Before takeoff, the pilot should have a look at a high-level pressure chart, the 300-mb one, which is about 30,000 feet. Its wandering isobars will show where the jet stream is apt to be. It’s like any pressure chart, with the distance between isobars telling how strong the wind is: the closer the stronger. In studying the wandering curve of the isobars, the pilot should note especially where the isobars bend and change direction. A trough, for example, will have the isobars oriented from northwest to southeast on the west side; then they will turn a corner and orient themselves southwest to northeast farther east. In the area of the corner, where the wind changes direction, you can almost count on finding CAT. Then check the isobar pattern. Let’s say the isobars are all crowded together in an east–west direction; the wind is moving fast. But farther east, the wind slackens, and the isobars fan out. It will be rough in the area where the wind

velocity changes and especially if the upper flow diverges. If the velocity changes faster than 40 knots in 150 miles, it’s a sign there will be considerable rough air. Jet streams above mountain wave areas have extra turbulence, and the choppy type found in the rotor will be found at high altitude, but not with the viciousness of the lower rotor. There is also wind data telling velocity change with height. Generally, it is considered that if one sees a wind change of 4 knots or more per 1,000 feet, it will be a rough area. This we find hard to count on. Sometimes it seems to work, but we’ve seen occasions where the 4 knots and everything else said it was going to be rough, only to fly through and never hit a ripple. If this figure coincides with other turbulence cues, like bends in the isobars, it seems more valid. At any rate, we watch these areas with suspicion.

The Tropopause and CAT Perhaps the most interesting thing to study in advance is the height of the tropopause (trop), which tells us a lot. The tropopause is the place where the troposphere, in which we live, ends and the stratosphere begins. The tropopause is a narrow band separating two different kinds of air. The most noticeable characteristic difference between them is temperature. As we know, the temperature decreases with altitude in the troposphere and keeps right on doing so until we reach the tropopause, where the temperature stops getting colder. This, theoretically, is at about 35,000 feet in the average latitude of the United States. Above the tropopause, in the stratosphere, the temperature is considered to be about −56 degrees C, but all this can vary considerably. To make life more interesting, the trop, as the trade calls it, wavers up and down with the passage of lows and highs under it, and can actually range in altitude from the low 20,000s to the 40,000s right over the United States. It also varies in seasons, usually lower in the cold of winter and higher in summer. The taught standard says the trop is high over the equator, at about 55,000 feet, and low near the poles, at about 24,000 feet.

The Tropopause Is Important A couple of things happen at the tropopause. The temperature goes up or holds steady, as we said, and there is a choppiness as you go through the torpopause into the stratosphere. This temperature change is an inversion, just like one 1,200 feet above the ground early in the morning. The inversion makes sort of a lid, and if there’s a jet stream, it will be fastest right under the tropopause. If this band of strong wind contains turbulence, it will be roughest right at the trop and for a few thousand feet below it. The depth of the region where the turbulence and wind are strongest is a point of argument, but personally we like to give turbulence at the

trop a 4,000-foot berth, that is, fly 4,000 feet under it. This doesn’t avoid all the turbulence, but makes it less bothersome. Above the trop, in the stratosphere, the turbulence dies out within a very short altitude range, usually 1,000 feet or less. If you get up out of the trop, it generally becomes smoother quickly, and the wind decreases, too. If one has a strong headwind, it is often possible to see it drop off dramatically as soon as one climbs into the stratosphere. So if we’re trying to avoid headwinds, the temperature is low enough, and our aircraft light enough for its given power to operate up there, the place to fly is above the trop, and it’ll probably be smooth, too. You’ll also be above much of the air traffic, allowing more direct routings. Pilots flying the many superb modern corporate jets, with cruise altitudes commonly above 40,000 feet, usually can smugly relax in serenely smooth air, as they listen on the radio to the rest of the flying world thrashing about in turbulence below, and who are begging for altitudes to alleviate it. Because jets fly between 28,000 and 45,000 feet or so, it’s simple to see that they wander in and out of the tropopause as they cross over high- and lowpressure areas. This means that our current jets generally fly at the most annoying altitudes. Every time you pass through the trop, it’s bumpy, and if there’s a lot of wind or turbulence, it may be very bumpy. Nuisance number two in the trop is the temperature change. You take off for a long trip with a heavy airplane and plan to cruise at 33,000 feet. The weather charts say it’s cool there, and the trop is well above you. Then, once in the air, ATC says to climb to 35,000 feet. As you go through 34,000 feet, there’s a little choppiness, and you can see a slight haze level. Your eyes dart to the outside air temperature gauge just in time to see it go up to a “warm” -44 degrees C. The airplane feels mushy in the “warm” air, and life is no longer beautiful. You are above the trop.

A simplified view of a tropopause chart and visualization of its effects on a Seattle-to-Chicago flight at 39,000 feet. This is usually an inconvenience, and you may be able to stick it out and stagger until the weight lowers through fuel use. On the other hand, the airplane’s performance may become too compromised, either by “running out of power” or we’re clipping the trop and it gets choppy. Then we’ll call ATC and tell them we just cannot fly up there. Then they have the problem of squeezing us back into the lower air traffic. All this makes studying the tropopause charts (trop charts) very important before a jet flight way up high. We’re looking for these things: 1. Trop heights

2. Trop temperatures 3. Trop wind direction and velocities 4. Vertical shear values We are interested in the trop level, especially in the area of takeoff and where we’ll reach climb altitude. For example, if the trop is supposed to be 33,000 feet and its temperature is at the warmest our aircraft can handle, we may not be able to climb higher immediately, even if we’d like to, because the temperature above the trop will be at least the same, if not warmer. We may have to stay lower until we fly into a higher trop area, or until we burn off fuel, are lighter, and have better altitude capability. Believe it or not, in today’s computerized weather, it is hard to find a trop chart or data. A lot of that data, which one could eye for a look at potential turbulence, is just published as potential turbulence areas. This is the dilemma of our new world of computerized forecasts versus seeing the data as an experienced pilot, applying it to previous experience, and then making our own wag at things. Admittedly, these forecasting methods are becoming quite good, but it seems these processes are encouraging pilots to be more responders to information, than curious and knowledgeable participants of where, why and how they fly. What was helpful on older charts was the vertical shear. It used to be on the chart, in little boxes with numbers. We might see a value such as “4,” shown in numeral form. This means the wind velocity changes 4 knots each 1,000 feet. We remember that the value of 4 or more is generally considered enough shear to call for turbulence, but as we said, it doesn’t always happen. A trop chart has many characteristics similar to other pressure charts. If the trop levels, shown in millibars, change greatly over a small distance, the winds will be high speed, and it’ll be rough. In a steep slope like that, the temperatures will change quickly and, as in a lusty cold front, there will be rough air. If the trop levels make a sudden change in direction, it will be rough there, too. With today’s computerization, if we find a trop chart, it’s worthwhile overlaying the trop chart on a turbulence forecast chart for respective altitudes, giving us something we can easily flick back and forth between, comparing and learning. There is an event known as “tropopause break,” where the trop steps with two different heights, no longer a connected portion of the atmosphere. That will be a trop height change just about on top of itself. This is a potential turbulent area worth noting. In summary, the trop information shows how high we’ll have to climb to be out of rough air and strong winds, as well as where it might get turbulent as we fly at trop altitude or transition through it. If we can climb above the trop, it gives us a better envelope in which to operate our flight. For high-flying jet aircraft, trop information is as important as the surface chart in telling weather. These aircraft spend their time either near, in, or above the trop, and familiarity with the phenomena is of utmost importance. We should

not plan such a flight without trop information, if at all possible, whether we get it from computerized data, a phone call to the FSS or a flight-briefing service. Pilots who fly at high altitudes should not be surprised by sudden turbulence if they have studied the weather carefully, especially the trop charts information and high-level pressure charts. After that, close observation in flight will show how the forecast charts are working out and, if they are not, how to modify one’s flight. Close monitoring of outside air temperature in flight provides further clues that changes are about to occur. There’s little excuse for “surprise” turbulence.

Shear Shear is an effect created by winds of different velocities and the cause of almost all turbulence. We feel it when flying from one wind strength to another. Flying from a strong headwind into a lighter wind, the airplane loses airspeed and must get it back. At cruising speed, this isn’t much of a problem, but at low speeds during an approach to landing, it can be significant. At landing-approach speed, we are not too far from stall. An abrupt airspeed loss, caused by flying out of a headwind, suddenly brings us much closer to the stall. We sink. If we don’t do anything about this, it will take a long time to get the speed back, many seconds, even a half-minute or more. In that time, we might get too low and hit short of the runway. We’re not only talking of the infamous thunderstorm wind shear events, but even a wind gradient issue on a seemingly nice, but somewhat windy day. When this speed loss occurs, we have to do something about it right away. We pull the nose up to keep from sinking and put on more power to overcome the drag from the pull-up. We can’t be bashful about quickly adding lots of power— all of it if necessary. The pull-up can be quite severe in an extreme condition, more so with highly powered aircraft like jets. In an event with severity, such as a thunderstorm wind shear event, it may be necessary to pull up almost to the stall angle of attack to get up and away from the ground. If the wind shear is strong, the airplane’s initial angle of attack will be low, because of the downward airflow from the storm. It is therefore necessary to change that to a big angle of attack, by raising our aircraft’s pitch-angle, in order to get the necessary lift. The pitch angle, what you see on the horizon, be it true or artificial, will be quite large, and it may look pretty desperate, but the actual angle of attack, the relative wind, will not be that extreme. During an event of this magnitude, maximum power must be used, with throttles right up to the limit! The task is not to exceed the stall angle of attack, and one will have to rely on one’s sense of feel and the stall-warning device on the airplane. This later situation usually has us flying so that we’re tickling the stall warning with an occasional beep of the aural warning. There are instruments available today that are specifically designed to help us fly through shear; they are usually found on

higher-end turbine aircraft, but with our rapidly changing technology they may filter into smaller aircraft. It is important to note that certain shear and vortex turbulence near a thunderstorm cannot be flown. The airplane cannot handle it, special instruments or not! The only positive, safe answer is not to attempt landing with a thunderstorm on or near the airport! If strong shear is encountered, requiring large attitude and power changes to combat it, a serious hazard then arises as the shear stabilizes and the pilot attempts to continue the landing, instead of initiating a missed approach. Where the shear avoidance maneuver is best done without trimming for the high attitude/angle of attack and power situation, one can inadvertently do so. When this happens the airplane is trimmed for this steep pitch attitude and excess power. To continue the landing, retrim, get the power off the right amount, and slide back into a decent approach slot for a safe landing requires some very difficult flying. This is magnified in airplanes that require large stabilizer travel or have higher performance characteristics, such as jets. Shear can also have a crosswind component, which will quickly push the airplane away from the runway centerline. So the pilot not only has to do some difficult trim, power, speed, and rate-of-descent juggling, but also has to turn the airplane and get it lined up with the runway, generally at low altitude. All this is very difficult flying and is possibly where shear accidents are sometimes caused. So if a pilot is fortunate enough to recover from the shear, it’s no time to press one’s luck and try to get lined up and land. The smart maneuver is a go-around! Shear is easier to cope with in a propeller airplane than a jet. The propeller airplane, when we pour on power, gives thrust quickly; it also can produce an immediate increase in airflow over the wing, depending on the aircraft’s configuration, from the propeller wash, and therefore adds lift almost immediately. The jet engine provides thrust only, which, if the throttle has been pulled full back and the engine spun down, will take time, and a long time if it is an older straight or low-bypass jet engine, in coming back to full power, so will take longer to regain speed. While all pilots have to be alert for shear, the jet pilot has to be particularly so. Also, lighter propeller aircraft, especially singles, don’t have the power to weight ratio of turboprops and jets, so we can’t depend on the same escape ability we hear of with turbine aircraft.

Where Is Shear? Shear happens in various ways. With winds usually stronger aloft and weaker near the ground, wind velocities change as we descend, producing shear. Shear also occurs due to shifts in wind direction. In thunderstorms, when a front is approaching an airport, we can easily get a wind change from southerly to northerly in an instant that will make landing an exciting adventure. This can also occur from winds spreading out from a later-stage thunderstorm’s down-flowing

air, which can happen quickly both in a storm situation and in a consequential rapid wind shift. More subtle, however, is a wind shift as we descend that changes a headwind into a crosswind and effectively makes the airplane’s velocity lower. A few hundred feet above the ground, the wind follows the isobars. That’s gradient wind . But the surface friction of the wind running over the ground causes the wind to flow more toward the low pressure, so the wind near the ground, instead of being easterly as the gradient wind might be, will swing toward the northeast and north as we descend. This, of course, cuts down its effective velocity and so produces a shear effect with an airspeed loss. It’s a good idea, when landing in a crosswind, to be conscious of the gradient wind direction. Is the wind aloft more of a tailwind in the direction we’re landing or a headwind? If it’s a tailwind, we may land too long or, worse, overshoot. For example, we are landing to the west. There’s a north wind on the ground. The wind aloft is east at about 40 knots at 1,000 feet. We are making our approach with a whopping tailwind. Our ground speed is high. As we descend, the tailwind decreases, but we only have a short period in which to get rid of a lot of ground speed before we get to the runway. We tend to overshoot, and so we push the nose over to get down to the runway’s end. Our speed increases, and lift becomes excessive. It’s difficult to touch down on the runway; it would be wise to abandon the approach. So we pull up and try landing to the east. Now we have a headwind aloft, but as we descend we lose the headwind and some airspeed. Now we’ll have to correct for sink and overcome the tendency to get below the glide path. It’s obviously important to consider the gradient wind as we let down to land. It will give us an idea of what to expect during the approach. Will we be scampering and diving to get down and land within the airport—a tailwind condition? Or will we be pouring on power, hoping to lift ourselves back on glide path, in order to keep from undershooting—a headwind condition. The similarity of these two examples is the decrease of either the headwind or tailwind, before reaching the runway. Sometimes the difference between the gradient wind and the surface wind can be quite high, even more so at night than in daytime. A nighttime inversion makes things seem still on the surface, but just above the inversion, the wind can be swishing along at 50 knots if there is a strong pressure gradient. We must therefore be wary of large differences between surface winds and winds aloft when the gradient is tight and there is a strong inversion. Warm fronts can create strong shear conditions when things on the ground seem tranquil. First, let’s review the wind directions on both sides of a warm front, as well as above and below the frontal surface. The frontal surface slopes generally toward the north, about 300 to 1, which says that 300 miles north of the surface front the front aloft will be at 5,280 feet above the ground. North of the front and below the frontal surface, the winds are light from the northeast. South

of the front, and above the frontal surface, they are south to southwesterly and often quite strong. Now let’s place a warm front 30 miles south of Kansas City, Missouri, where we will land. The surface wind at the airport is a gentle 10 knots or less and northerly, but above 600 feet, the wind is southwest at 50 knots! So as we descend toward 600 feet, we have a tailwind of 50 knots. Our rate of descent will be high to stay on the approach path and so will our ground speed. We’re all set for an overshoot. This isn’t just hypothesis. It has actually occurred at Kansas City. A warm front situation is not especially bad, because we may have to go around. It becomes serious when the pilot doesn’t go around and tries to make a landing, touches down well along the runway, and goes off the end into who knows what! Overshoots may also put us in a position to undershoot. Descending fast, trying to get down to the glideslope, we pull off all power. Then we run out of that strong tailwind. Our ground speed slows, but airspeed increases from an effective headwind, and we go above glideslope. In our effort to get back down, our power is still reduced to idle. Then, sooner than we realize, the airplane goes below glideslope, and we are undershooting! Now it’s pull the nose up and pour on power. This can be quite a juggling act, especially on instruments. The main thing we need to remember is that winds only a short distance above the earth can be very different from winds on the surface. Tailwind-to-headwind, wind reducing in descent, wind increasing in descent, or headwind-to-tailwind, they all require different recovery techniques and aren’t restricted to warm fronts, but can be experienced with cold fronts, nearby thunderstorms, mountain downdrafts, and anything that can give the wind different vectors and velocities. All this theoretical talk isn’t much good if we don’t know where fronts are or if we suddenly run into shear conditions and don’t know why they are there. Then what? First let’s recall the two basic things about shear: • A headwind on landing tends to make us land short when wind velocity decreases. • A tailwind on landing tends to make us overshoot. What we want to know is how strong the conditions are and how much the wind will change during descent. In fancier language, what is the wind gradient? This is part of our weather briefing, giving thought to wind changes with altitude near the ground at takeoff and landing. Once in the air, the sophisticated way to know wind gradient is by having wind information on our instrumentation that tells wind direction, velocity, and aircraft ground speed. We find all of this on glass-cockpit aircraft, and at least ground speed on individual GPS systems and older IRS-equipped aircraft. The wind direction needles allow us to see the wind direction change as we feel the

little choppiness in the air. The digital velocity tells us the magnitude of the wind and the “watch out” factor. With only a ground speed reading, if we are on final approach and our ground speed is lower than indicated airspeed, which is a headwind, and the surface wind is not very strong, there’s a steep wind gradient. This means we’d better be ready for that undershoot situation when we fly out of the headwind lower in the approach. A high ground speed means a tailwind and an overshoot. With actual wind direction and velocity available to the pilot, one can compare it with the latest reported surface wind and know how much change there will be in descent. If we are without this helpful wind data, and we’re on an ILS or any precision approach of normal three-degree glideslope, it’s fairly easy to get an idea of what’s going on by our rate of descent. Let’s say our approach speed is 120 knots. To make good a three-degree glideslope, without wind, we’ll descend about 600 feet per minute. So, if we find that it only requires 400 feet per minute to stay on the glideslope, we’ve got about a 40-knot headwind; in other words, an 80-knot ground speed needing a 400 feet per minute glides-lope. If the surface wind is 10 knots, then somewhere during descent, we’re going to lose 30 knots and have to get power on and scramble to keep from getting too low. On the other hand, if our necessary descent rate to stay on the glideslope is near 800 feet per minute, then we’ve got a 40-knot tailwind, and it’s going to be a scramble not to overshoot. Required descent rates versus ground speed often are listed on the bottom of approach plates, but if they aren’t, there’s a formula to help decide what the ground speed should be. Half the ground speed times ten equals the descent rate, or nearly so. Take our 120 knots; half of that is 60, which times 10 equals 600 feet per minute. This is 36 feet per minute short, but is pretty close as the VSI reads. This, of course, is for a normal three-degree glideslope. We can do it backward: if we’re coming down the glideslope at, say, 900 feet per minute, we can divide that by 10, which equals 90, and multiply that by 2, which comes out 180, and that’s our ground speed. If our normal speed is 120 knots, we’ve got a 60-knot tailwind! These numbers are for true airspeed, which if we’re near sea level and the temperatures aren’t wildly off standard, will be pretty good. If we’re landing at a 5,000-feet-above-sea-level airport, however, we’ll have to compute what the true airspeed (TAS) is for our 120-knot indicated airspeed (IAS) approach speed. A wag is 2 percent increase over indicated per 1,000 feet above sea level: at 5,000 feet that’s 2% × 5 = 10%, and for 120 knots, that’s 12 knots. So we have a true airspeed of 132 knots, give or take. Formulas, put up somewhere handy in the cockpit, will also be useful to help figure ahead of time the descent rate you’ll have to use coming down on the ILS when you have a rough idea of the descent winds. For one’s particular airplane, with which we always use a certain approach speed, it’s possible to mark the ground speeds opposite the appropriate descent rates next to the vertical speed

indicator—if we’re flying a good old round-dial instrument system. With a glass cockpit, despite the myriad of guidance, you’ll still have that low-level wind dance that is cured only by good flying ability—and judgment of whether it won’t work and it’s smart to go around. A visual approach is more difficult, because there isn’t any exact glideslope guidance, unless there’s a Visual Approach Slope Indicator (VASI ) or Precision Approach Path Indicator (PAPI ), and other types, which are all grouped as Visual Glide Slope Indicators (VGSI ) in this acronym world, which you can pick up well out from the runway. Staying on a VGSI glide path, and seeing what rate of descent is needed to stay with the glide path, is the same as coming down an ILS glide path of three degrees, if the VGSI is matched to the same angle—and most of them are. An all-visual approach, without a visual or electronic glide path reference to help, means getting back to basics. If we can pick a spot on the ground we want to land on, and then watch it in relation to our descent path, we know how we are doing. If the spot climbs in the windshield, we’re undershooting, and if it descends, we’re overshooting. So it’s a sort of visual glide path. If we notice it’s taking lots of power and a higher-than-normal nose attitude, we’ve got a headwind. However, if the nose is down, and we keep wanting to pull off power, we have a tailwind. It isn’t always possible to pick a spot in poor visibility or way out from the airport. If it isn’t, then it’s eyeballing the situation and using one’s good seat-ofthe-pants feeling and visual cues that come naturally over years of experience. If we’re dragging in, there’s a headwind, and vice versa. Another type of shear is caused by gusty winds. It’s obvious that a wind blowing 10 knots and gusting to 20 can give one a very quick airspeed change of 10 knots. That’s why, on gusty days, it is wise to carry extra airspeed to take care of these “sinkers” on approach, as a gust dies down and leaves one low on airspeed. One popular correction factor takes the normal approach speed and adds half the gust velocity as a cushion during gusty conditions, plus another 5 knots if the wind is above 15 or 20 knots. Shear is often overlooked as a takeoff hazard, but it’s as important then as in landing. There have been cases where a takeoff was made into a headwind with a strong opposite wind (tailwind) whistling along just above the ground and resulted in an accident. If flying from an airport with ATIS information saying “wind shear advisories in effect,” we take it seriously and plan our takeoff accordingly, even if it means reconsidering the departure altogether. This, of course, applies as a heads-up to arrivals, as well. If there is a front of any sort near the departure point, we should carefully consider a wind shift, looking for information of frontal location, NEXRAD, if we have it, (considering a 10 to 20 minute delay in the data), or possibly an ATIS/ASOS/AWOS from a nearby, upwind airport as to timing of a wind shift,

any precipitation, and so on. If really close, it’s worth looking upwind for blowing smoke, dust or dirt, its direction and ferocity, before taking off. With a thunderstorm nearby, we should be prepared for a wind direction change after takeoff, let alone the turbulence and all else that makes a close thunderstorm departure something to reconsider. A thunderstorm, realistically, is the weather most likely to be violent enough to make the dramatic wind shift that causes trouble. To be pedantic and repetitive, a thunderstorm near the airport, landing or taking off, is a very real danger, and sometimes one that cannot be flown successfully. To say it as emphatically as possible, do not land or take off close to thunderstorms. Our present use of radar, both in the airplane and by ATC, tends to have airplanes cutting in too close to thunderstorms. Often a mild-looking storm just off the approach path can suddenly, in moments, reach the point where it dumps water and wind in violent fashion. Thunderstorms are not static; they are constantly changing. They are something to give wide berth. The accidents that have occurred on approach to landing and takeoff are a gruesome enough proof. What do we do about all this? If the front or thunderstorm is close and strong, let’s wait until it passes. If we get caught, because we didn’t think it was that bad, then consider that a loss of 50 knots, or a severe downdraft, is going to require an excess of speed as soon as possible after getting airborne. We want to get that excess quickly, remembering, of course, not to fly back into the ground or get too low when we’re taking off into the unseen abyss of night, or on instruments, while in the process. Sudden airspeed changes due to shear, bumps, or whatever affect the aircraft’s pitch attitudes. Two points: when getting a positive airspeed increase, or rising gust, the nose will pitch up; when going from a headwind to a tailwind, or descending gust, the nose will pitch down. So we’re taking off into a headwind and suddenly, right off the ground, we get an airspeed loss from a descending gust. Airspeed drops, and so does the nose. We should be prepared for this and, as in all flying, hang on to the pitch attitude we want. This is also why we do not want to chase these pitch changes with trim. Having flown a lot of these scenarios in simulators, you want to just fly the airplane with whatever force you need and as much finesse as possible, so when things return to normal, the airplane isn’t all screwed up with wild control forces, which, as said before, only adds to the event’s problems.

Thermals There’s another effect that isn’t strictly shear but acts in much the same way. It comes from thermals, the kind glider pilots look for: rising pieces of air. On a summer day, we approach a runway. Perhaps there isn’t much wind at all, but before reaching the runway, we get a bit of sink and have to pull the nose up and add power. Then we cross the runway and suddenly seem to have excess lift

and float for a long distance before the airplane will touch down. What happened? Chances are that this was an approach to a paved runway surrounded by grass or other vegetation. If we could see air circulation, we’d notice lifting air coming up off the paved runway and then (because when some air goes up, some other air must come down to replace it), we’d probably see air sinking over the grass adjacent to the runway. On our approach we’d fly through the sinking air over the vegetation; then, over the runway, we’d fly into the lifting air that would want to keep us up. The opposite will occur at night, with lift over the warmth-retaining vegetation and sink over the cooling runway. That’s why we sometimes go clump in a hard landing at night and wonder why. We flew into sinking air. The night effect, however, isn’t as strong as the daytime effect. This also works approaching a runway right at the end of a body of water; sometimes even more so. One day, (ROB) approaching Boston’s runway 27, in a 727, on a very windy day with lots of thermals, this sink–lift–sink routine added another sequence at about touchdown, but we didn’t touch—we kissed and ballooned. It felt like a J-3 Cub, buoyantly floating along, so much so that milking the 727 down before running out of runway seemed very unlikely. Blasting off in a go-around, we caught a glance overhead of a glider pilot’s dream—a beautiful dark-bottomed summer cumulus, full of lift. The important part of all this is that when sink occurs short of a runway, be it due to speed loss from shear or a thermal, we must be ready to use power and keep our airplane flying on the approach path which we have selected, either visual or instrument, and not allow it to land short. Conversely, if you run into lift and find yourself floating along like you’re sitting on a cloud, without excessive runway length, make that go-around.

12 VFR—Flying Weather Visually Some of us fly VFR because we don’t know how to fly instruments. There isn’t any doubt that a pilot who is serious about using an aircraft for transportation should learn instrument flying and obtain a rating as soon as possible. It makes flying safer, more useful and offers the enjoyable satisfaction of learning a new level of challenge and proficiency. Knowing instrument flying makes for safer flying because a pilot doesn’t get trapped in bad situations. If cornered, you pour on power, pull up to a safe height, and think over what is best to do. It isn’t necessary to poke along between mountains or duck communication towers, windmills, and other skyward intrusions when ceilings and visibilities are low. Most of the time, an instrumentrated pilot can be on top, in sunshine, enjoying the flight, rather than nervously and dangerously picking along in reduced visibility. In the early days of airmail—the days of open cockpits, helmet, and goggles —the pilots didn’t fly instruments; they dangerously stayed “contact” and strained eyes and nerves trying to see what was coming up. That was when the Allegheny Mountains were called Hell’s Stretch. Pilots plowed into them regularly, leaving broken bodies and airplanes on the rugged slopes. In the first year of the airmail service, as many pilots were lost as were employed by the service. It pays to be instrument qualified, and every day it becomes more necessary, as the airway system grows in complexity. Modern aircraft equipment has become more sophisticated and compatible with weather flying, so that instrument flying is an integral part of all flying. To restrict oneself to VFR flight means one will have less and less area to fly in, and someday VFR flight may only be possible in limited zones under strict control. It also means we are not using general aviation to its full potential. Aside from all that, an instrument-qualified pilot is a safer pilot, and it is difficult for us to visualize being in the sky without the ability to fly by instruments. Night flying, surprisingly, is often instrument flying. Take off at night, down a lighted runway, then, as the runway falls behind, we are suddenly in a black hole with no visual reference. We’re on instruments! Whether right after takeoff or for that matter in any phase of flight, seconds of disorientation from improper “blindflying” instrument response can be fatal. Also, as said before and will continue to be harped upon, an autopilot is not an acceptable bridge for the pilot unable to manage a hand-flown aircraft in instrument flight. Overall, the record shows that more VFR accidents occur at night than in the daytime. If we’re going to fly at

night, we need to know how to fly by instruments.

VFR There’s still a lot of VFR flying, and as a matter of fact most flying is VFR. There isn’t anything wrong with it, if the limitations are known and followed. First, always, is the fact that in flying VFR one must see! Low clouds and poor visibilities make this difficult. Rough terrain makes it worse. A key to safe VFR is not to get in a position where the visibility is so bad we cannot see enough to make a normal 180° turn and get out. It’s worth trying on a clear day, noting points on the ground, to see how much room it takes to turn. Then, at least double that distance for a cushion in actual weather. However, that is still pretty lousy visibility, and hopefully, we do not let ourselves get into such a predicament, but at least we now have sense of when that visibility is too low and we had better turn around.

The Famous 180 Two things are important. One is that the weather will not always have a nice, clear-cut edge that separates VFR from IFR, so a 180° turn may not always bring us right back to VFR conditions. While we’ve been sneaking along VFR, the IFR weather may have been sneaking along right behind us, and when the 180° turn is accomplished, we’re still face-to-face with marginal to below VFR. Keep an occasional watch behind to see what’s sneaking up on us. Point two is that limited instrument flying ability, which came with that minimum of instrument instruction when first learning to fly—including being shown that 180° turn to get us out of bad weather—is not sufficient to get involved with IFR flying. That minimum instrument flying instruction was for a dire emergency only! With rapidly deteriorating weather, a simple 180 can turn into a full instrument workout and we’d better be able to handle it. If committed to a 180° turn, and the visibility reference is poor, concentrate on the instruments: holding altitude, maintaining airspeed, keeping a proper bank angle until the return heading is achieved. But remember, without full instrument flying ability, this is very dangerous stuff!

Flying into the picture: IFR yes, VFR no. It’s obvious the weather ahead is worsening. This was near Tulsa, Oklahoma, with a summertime warm front and thunderstorms. A pilot should have a good picture of the weather and actual reports before poking around in this. In VFR flying, it is especially important to be flying toward better weather. VFR flying demands a good knowledge of the weather situation, and a VFR pilot should study weather in advance as much, if not more, than an IFR pilot. A nice day at the takeoff point doesn’t mean it will be nice for the entire route. The VFR pilot must be especially aware of any possible weather deterioration. If it goes sour, staying “contact” is a must, and this can mean getting too low in reduced visibility—a perfect formula for trouble! The IFR pilot is interested in trends, but deterioration may mean simply shooting a low approach or going to an alternate. When the weather goes sour, the IFR pilot does not get into trouble as deeply or quickly as the VFR pilot. So the VFR pilot needs a good look at the synoptic situation: where fronts are and their expected movements, plus the en route and terminal forecasts, as well as a good look at satellite, radar, and weather depiction data. We also remember our admonition about areas marked MVFR— Marginal VFR. Unless the trend is for improvement, stay out of these areas and, at best, keep a sharp eye on what the weather is doing when flying through MVFR areas. Basic weather rules for a VFR flight are these: Fly toward improving weather; do not fly toward approaching fronts. Especially do not attempt to “beat” a front to your destination. Be extra conscious of destination forecasts when flying

toward evening, shorelines, heavy industrial areas, and mountainous regions. Also take special care in spring and fall, when the days are warm and the nights cool, particularly if there’s a lot of moisture on the ground and in the air near the ground. We get this when lots of rain has fallen, and particularly when there is snow on the ground that has been rained on or subjected to melting during the day. We all know the feel of those clammy, cold nights and moisture-laden air; they easily make fog. If there isn’t any frontal condition, but cloud decks are forecast because of postfrontal air masses, be alert to the fact that clouds in mountainous areas will tend to be overcast and close to or on the mountaintops. If the air mass is vigorous, there will be showers and low visibilities. The weather will be as difficult as a front. Flying in mountainous regions requires more visibility than in flat terrain, because clouds tend to hang on mountains and blend in, so mountains and clouds often look alike. The slopes are difficult to see, and one comes up on them fast, even at 100 miles an hour. A good rule is that if you cannot see the mountaintops, with space between them and the cloud bases, it’s a poor time to be flying. There are, however, some conditions where there is excellent visibility, 20 miles or more, and we can fly down valleys with the mountaintops in cloud. But the forecast must be solid gold to stay good! The first snowflake or raindrop and it’s time to find a place to land. And always be certain there’s an entry and exit to the valley, because you cannot climb over the mountains to get out. Flying into a cul-de-sac—a dead-end valley —is bad, bad news. When checking weather for flight across mountainous areas, be aware that the METARs or an ASOS/AWOS may show adequate ceiling and visibility at departure and destination airports, but lack reports for areas en route that may be much higher terrain than departure or arrival airports. There might be adequate ceiling and visibility at the departure and arrival, but zero-zero in high terrain en route. Such was the case in our picture that looks on top of valley fog, a bit further in the chapter (on page 190).

A Point to Remember A VFR point worth thinking about is that the closer one gets to the cloud base, the worse the visibility. As the ceiling squeezes a pilot lower and lower, the tendency is to try and stay as high as possible. In doing so, the airplane crowds the base of the overcast. (If we’re not careful, this can become illegal, in relation to regulations of VFR flight and cloud separation.) Also, the base of a cloud isn’t clean-cut; mist and shredded hunks of vapor, like a gossamer veil, hang down below the solid part. Pilots can be flying in this area and see the ground straight down, but ahead, because we are looking through a lot of ragged stuff hanging

from the cloud base, the visibility is low or nil. Descending a little, sometimes only 50 feet, the visibility may suddenly improve. If it doesn’t improve in 50 to 100 feet, then the bottom of the cloud isn’t the problem, and it will not pay to go lower; it might actually be dangerous because of getting too close to the ground. We may be boxed into real trouble.

Snow Is Different This idea of going a little bit lower to improve the visibility doesn’t hold true in snow. Often, in snow, the ceiling is quite high. Snow generally forms directly from water vapor without any cloud process, and one doesn’t get “in” a cloud. In professional jargon, this process is called sublimation . Because there isn’t cloud in this kind of snow, there generally isn’t any ice. It takes the supercooled water in a cloud to make ice: no cloud, no ice (except in the case of freezing rain). Therefore, if a pilot is in snow with the ground visible, he or she can pretty well relax as far as ice on wings and propeller is concerned. Snow can come from nimbostratus clouds and snow showers from cumulus. These clouds are easy to avoid—generally by flying on top. Nimbostratus, or stratocumulus, is the kind we find over mountains after a cold front. Snow showers in cumulus would be in unstable air, so on top is again the place to be, but the tops may be high. The clouds that have snow must contain supercooled water, and they get that by the lifting caused by strong instability or in air that’s been lifted mechanically by wind pushing it up a mountainside. Generally, however, there isn’t ice in large areas of snow. If ice forms, you are either in a lower cloud deck—and hopefully finding this out during an IFR flight—which you can top, or you are near the frontal surface. More on that later. The heat of the engine and windshield may cause snow to melt and refreeze as slush, just as on an automobile windshield on a snowy day. Because of this, a pilot flying a piston-engine aircraft has to keep an eye out for carburetor ice all the time and for engine intakes getting plugged up after a long period of flying in snow. Flying in snow caused by overrunning air ahead of a warm front, which is usually a general area of snow, one can see the ground straight down from quite a few thousand feet. Of course, the visibility ahead will be very poor, because we’re looking through a lot of snow. Because the snow forms aloft and falls to the ground, the restriction in visibility caused by the snow takes in all the sky, so going lower will not improve visibility. People are sometimes fooled by snow and fly lower and lower, because they can see the ground straight down, thinking they should be able to get “under” the stuff. In fact, they cannot get “under” it and sometimes get hurt trying to do so. A pure VFR pilot had best stay out of snow areas, because the visibility will be poor regardless of the ceiling. Once snow starts, even light snow, the visibility will become poor in a short time.

A VFR pilot prowling along under leaden skies will often have good visibility, but when snow starts and the first white streaks go by, it’s time, right then, to think about going elsewhere or finding a place to land. The first flakes of snow are almost always a loud and clear signal that things are going to get worse. It’s no time to keep poking ahead and hoping for better. Sometimes, ahead of warm fronts, snow begins to fall very quickly in a fairly wide area, 100 miles wide or more, so that one must consider the unpleasant possibility that a 180° turn will not get us out of the condition, because the snow may start, at the same time, all around us and for many miles behind. All this relates back to the point that we should study weather in advance and know, in our mind, what could happen and which way to duck if it does. When precipitation begins, especially snow, a pilot shouldn’t sit fat, dumb, and happy until things get worse. It’s time to do something before that, whether trying to turn around or go somewhere else and land. This potential situation is another good argument for excellent navigation, keeping sharp awareness of our position and where the nearest airport is located. This means geographically—terrain, built-up areas, obstructions, air-space restrictions, and so forth—from sectional charts, whether paper or electronically displayed, and not just a line on a featureless GPS screen, or heading and distance to a point.

Keep Calm When we say go somewhere and land, we don’t mean to do so in a panicky fashion. The worst thing we can do, in any situation, is get frantic, dash for Mother Earth, and land in the first field that comes along. If possible, we ought to stick to airports, and ones that fit the airplane. Of course, this isn’t always possible, and more on that when we discuss “Not Only Airports” in a couple of pages.

More Snow Just to confuse things, snow can also be found falling out of clouds. This condition is generally found in air-mass weather, such as a stratocumulus deck behind a cold front. Snow falls from the clouds, and the clouds have ice in them. In mountains, the higher ridges are in the clouds, and these are conditions a VFR pilot should avoid. The mountains of Pennsylvania, after a cold front passage in winter, are generally cloud-covered and get lots of snow, with the visibility poor to zero. It’s not a frontal condition, but nevertheless it’s a tough one for VFR. It’s not a place to try to fly VFR underneath the clouds. The only way is on top, and that will require an instrument climb with ice in the clouds, their tops 8,000 to 12,000 feet, or even higher over tall mountain terrain, such as the western United States.

Low stratus clouds, giving poor ceilings, increase as one gets closer to a front. In these clouds, there are snow and ice; the snow, however, will be falling through the clouds from someplace above them. A pilot will be in snow, but this time the ground will only be occasionally visible through breaks. There will be ice in the stratus clouds. At best, this isn’t a good place for VFR flying. We’ll talk more about it later when discussing instrument flying in weather. We can say, in passing, that an instrument-rated pilot can pull up and get on top of these iceproducing clouds, assuming the aircraft can handle ice, both physically and legally, in order to climb through it. Such IFR flight will be between layers but mostly on instruments, because the snow will cut visibility practically to zero. It will be a white-gray world without reference—for instrument pilots only.

Towers VFR pilots sneaking along over flat country have to be wary of television (TV) and radio transmission towers. They stick up dangerously high, not uncommonly to 1,000 feet above the ground, and some reach 2,000 feet. Add their supporting cables, extending way out to their sides, they are skinny and nearly invisible, even those with strobe lights—at least until they are suddenly right in front of us, with no place to go. Also, the communications folks have a way of putting them on mountaintops. Lower towers, such as those for microwave and cell phone service, usually under 1,000 feet above ground, are everywhere—especially on the peaks of hills and mountains. There is a proliferation of seemingly innocuous towers under 200 feet above ground. Used for meteorological and other information, their “under-200” height falls outside the FAA’s regulations for tall structures requiring strobe lights, brightly painted structures, and, worse, notification of their installation. That means they are not on the maps and the GPS units that display obstacles. They spring up overnight, at the whim of those desiring their utility. In flat lands, these towers have been fatal to agricultural aircraft and helicopter operations, but consider when these towers under 200 feet tall, as well as other towers, even if taller and noted on maps and GPS units, are placed on that hill or mountaintop you are grimly sneaking over in lousy visibility and low-hanging scud that also may be hiding those towers. We may think sneaking around so low to the ground is not our style, however, it is amazing how quick and desperate things can get when we push into compromising weather. Suddenly, we’re stuck, knowing we can’t stop in mid air, but the sky and ground are rapidly squeezing together.

VFR Navigation—and the Important Map On any VFR flight, the pilot should know, at any time, the accurate location of the

aircraft, preferably down to the mile. Yes, its old-school precision, but this theory will eventually prove its worth. We can’t afford it any other way. This means any VFR pilot must be sharp with themselves navigating by a sectional map—or chart if you wish—even if an electronic one, and not through dependence on a GPS or VOR navigating for them; instead, finger on the map and looking out the window. If a pilot isn’t well honed at precise VFR navigation, one should consider raising their ceiling and visibility requirements to a higher value; say 3,000 feet and 10 miles as a starter. With the advent of GPS navigation, we know where we are at a moment’s glance. Or do we? Not all GPS navigation systems are created equal; in this case, meaning how the information is displayed. Depending how fancy our GPS is, it might just have a line on a screen, or it could be the animated display of terrain, obstacles, airports, airspace, and even weather information. However, for VFR flight, we should have all the information we need, for the navigation process, located in one place. The best, most user suitable and complete source for this official information is a sectional chart, whether a good old paper one or an electronically displayed version. Probably the most ideal arrangement for VFRflying is one of the GPS displays that show our position on a moving map display, over an official electronically displayed sectional chart. Anything less than current sectional chart information, whether paper or electric, is really not an adequate choice for VFR flight. As mentioned earlier, the system of VFR navigation is different than IFR because we have to maintain at least legal visual conditions, with better than legal as more prudent. VFR also means it’s our responsibility to avoid unauthorized airspace intrusion, but most important is not running into anything, whether it is terrain, obstacles, or other aircraft. Our reference to all this, except for other aircraft, is off a sectional chart, but ultimately must be seen for real, by our eyes looking out of the aircraft, not at an electronic display. Up high on a lovely clear day, our VFR flight may be following IFR routes with ATC flight-following, which can give us terrain clearance and helps avoid other aircraft. This means we’re probably navigating with either VORs or a GPS. But since we’re VFR, an airway facility IFR chart is not an adequate VFR chart, just as a line on a vague GPS screen isn’t either. One reason is obvious lack of VFR information, but also because we can’t guarantee the weather will let us stay high and in the clear, instead the weather deteriorates, forcing us to descend into the many concerns we reference from sectional charts. Let’s say our clear VFR day has caught up to a weather system. Or, maybe we started the flight earlier in the morning, then in a couple of hours the sun has caused thermals to form cumulus, and they have gone from scattered to broken and now we have to get below them before we’re trapped on top. All of a sudden we’re down below the haze layer, the visibility is less, we’re at conflict altitude to airspace, and below IFR altitudes that give us terrain clearance. Down low we

don’t see as far and there aren’t as many clues available to help interpret a map. Our area of vision takes in a smaller area, even with good visibility, but even worse in poor weather where the visual range is even less. Now those cumulus start to spit rain or snow showers, the ceiling lowers further because we’re in hilly terrain, and we’re spooking around no more than a couple of thousand feet above the ground in visibility pushing the three mile VFR limit. At best, we’d better have an accurate altimeter setting, which we find by making ourselves even busier in the cockpit, looking for ASOS/AWOS or VOR frequencies and tuning them, or fiddling with electronics to call them up data on an MFD. If we’re really not clever, and things get really tight with visibility and ceiling, we may have little if any time to fly the airplane, check the map for information, and not hit anything—let alone fiddle with electronics. I (ROB) will tell you this is not a conjecture. I’m not proud of it, and the unacceptable disclaimer is that it was decades ago where fleetness of imprudent youth, coupled with a docile Cessna 182, being over home country, and undeserving luck, saved the day. Obviously, if the visibility and/or ceiling is that lousy, we’d best be on top of our navigation and terrain awareness, heading for a nice airport, where we land and wait out the bad weather. But let’s say the weather is okay to press on, although not stellar. This is where we must have that sectional chart information. The list of the chart’s offerings is huge, but again key items include terrain, towers, airspace issues, navigation and communication information, as well as that ever important airport to where we can run if things get tough. And constantly knowing position also means knowing where that nearest airport is located; it might be one recently passed, off to the side, or not far ahead, but we ought to know where it is. With GPS we have some help with this closest-airport process. One is the button we can push to find that closest airport. However, that will give us a direct routing to the airport, which might be over unapproved airspace (also usually shown on GPS) or more importantly terrain we’re above and can’t see because of poor visibility or darkness. Again, we have to know where we are! Another goodie of GPS is the terrain function, which warns us of terrain, towers and other intrusions into the sky in front of us. And that “synthetic vision” displayed on a PFD? It’s great reference too, but none of these warnings are approved for terrain navigation! Again, our eyes need to identify what’s outside, not what’s on an electronic screen. And the accuracy of these GPS-displayed terrain features is only as good as the currency of the GPS’s databases. So again, reference to that map is golden, but then they have to be current, too! A theory worth considering concerns navigating by paper sectional chart versus GPS moving map. Using the map means we’re looking in at the map, out at the sky and terrain, flying the airplane, then back inside to the map and so forth. Done correctly, we’re really on the ball! With a GPS moving-map display, a lot of

the work is being done for us, breading temptation to “follow the bouncing ball,” instead of the proactive event with navigation awareness. Also, it’s temptation that entices us to look inside more, not just at the moving-map but for button pushing and fiddling with electronics, taking just quick glances outside for aircraft operation instead of overall awareness or sky and terrain. And where are we with that within-a-mile navigation accuracy…referencing outside, not that little point on the moving map? This doesn’t mean we shouldn’t use the moving map, but make sure we discipline ourselves to be, when VFR, outside-pilots. We might want to think about using autopilots when down low and dirty, VFR in lousy weather. It can give us time to better manage the whole situation, spending more time with navigation and other stuff. On the other hand, if the weather is getting really poor, we should fly mostly with our eyes outside, both for flight and location reference; especially if we don’t want that fancy autopilot driving us into a hill or tower. So, down low and in poor weather, there’s argument to it being a hand-flown, navigating, and terrain avoiding issue, being able to maneuver efficiently and relatively quickly; not putting delay in our maneuvering by twisting a knob, then wait for that command to manuver the airplane through autopilot-servos. Handflying can arguably function almost subconsciously, with imminent reaction. On maneuvering in tight quarters, it’s one thing to be doing it in a very docile, “old-wing” type of airplane, especially if you had big fowler flaps that could slow you down in tight situations. Like any airplane, you have limits and can’t get lazy about them but it’s more forgiving than some of the newer, thin-fast wings, which with their faster speeds also have wider turning radius; a consideration if in tight quarters. In high-terrain we need to keep in mind high-tension wires that may cross valleys, following railroads that may go into a tunnel of terrain hidden by cloud, or those towers we’ve mentioned. Crowding a mountainside too closely could possibly cause one to clip the wires of a ski or utility lift that may be difficult to see, summer and winter. A number of glider accidents have occurred in the Alps in exactly this manner. This kind of flying is desperate, not to mention illegal, and no one should be doing it. We mention it only in case we get ourselves in such a fix and, illegal or not, wanting out in one piece! A few last thoughts on sectional charts. One is to have a current set—and as said before and will come up again—that is organized and folded to our route, easily accessible whether it’s primary reference, or backup to electronic sectional information. The biggest reason—if that GPS quits, we’d better pick up with that paper chart right away, because, unless we know the country we’re over, in just minutes we’ll be far enough down the road to being very lost. Another benefit of sectionals is that they are excellent for planning our flights, spreading them out before the trip, looking at the terrain, airspace and consider our weather briefing information in relation to the geography and route. And lastly, handing a sectional

chart to our passengers, with the route drawn on it, can engage them in the flight. This is beneficial whether they’re curious, a bit nervous, or prone to airsickness… it can keep them occupied. So flying cross-country as a VFR pilot? Use that sectional information, practice navigation, be smart, then humble enough to accept a modest motel in strange port-of-call, as an appreciated alternative to flying VFR in risky, bad weather.

Not Only Airports If we’re in a jam, stuck with IFR and no place to go, there may be relief right under us. It isn’t always necessary to land on an airport, and the “gotta get to an airport” fixation may work us into a deeper jam than picking a field and landing in it. Landing at other than an airport may seem well outside the box, but it does not have to be. Realizing that many of today’s aircraft are the same designs, or at least have similar landing speeds, of those decades ago, when field landings were not such a distant idea. I (ROB) remember a day when just a kid, where my father said we should drive to the golf course and check out a Globe Swift—a neat twoseat, low-wing little airplane. The weather was low in bad visibility, and the VFR pilot was smart enough to pick the long par 5, 15 th hole, as his “ace-in-the-hole” (pun intended), for safe landing. He must have known the alternative was to risk running into the fog-shrouded Watchung Hills of central New Jersey. The next day, in clear skies, he got the okay to takeoff, weaving around the 15 th tee, going safely on his way. When one considers many fields are just unpaved runways, off-airport landings seem more palatable. This is a place to use short and soft field-landing techniques. Glider pilots land in fields, and learning how is part of their training. In glider talk, it’s called “off-field landing,” meaning off-airport. Admittedly, gliders—or sailplanes in this day and age—have the advantage from somewhat slower landing speeds and usually having excellent dive brakes to get us down over obstacles; and less mass to get stopped. General aviation aircraft like a Cessna 172 with big flaps can slow down and land pretty short. In any event, knowing how to do this is another reason for power pilots to consider some glider training and experience—plus it is fun; the soaring, that is! Of course, landing in a field or pasture does need care and some planning, with the realization that there are cases that might lead to a bit of damage, such as messing up a nose wheel. However, we are making a choice of getting on the ground safely in lieu of flying along until we can’t see where we are going, running into something, or losing control of the airplane in instrument conditions. The accident reports, often fatal, state the cause as “continued VFR into Instrument conditions.” Let’s take a look at picking a place to land “off-field.”

First, take it easy and take your time. Don’t rush! Look the field over for rocks, ditches, large wet areas, and severe undulations. Check its slope, both the long way and side to side. It is usually best to land up a slope, even with some tailwind, versus your airplane’s glide angle chasing the slope and eventually running out of room to land. Side slopes can be tricky for these, we should plan to land in a gently banked, arched diagonal to the slope, starting uphill and ending the landing roll before starting back down the hill. As to what we look for in an off-airport landing, our favorite is a nice stubble field of cut hay or wheat, and hopefully not wet; darker areas in a field hint of moist areas. Beware after rains and snowmelt. Plowed field issues depend on how deep the dirt is, or again, if it’s wet. If in furrows, whether plowed-field or crops, land with them—not across—trying to put the wheels in the furrows, especially the nose wheel. (Stubble and plowed fields cause little if any crop damage.) Higher crops can grab a low wing and possibly cause a ground loop, so we want to keep our wing’s level and be slow but still under control. Mature corn with ears does not do favors for leading edges. High grass and uncut fields are unknown quantities as to possible gopher holes, rocks, and so on. Hidden ditches and fences are unwelcome surprises, especially barbed wire. With low canopies, as in gliders, barbed wire acts like a horizontal guillotine. Deeper snow, especially with a crust, is a natural arresting hook, but you risk gear damage and maybe flipping the aircraft; beautiful snowy countryside is suddenly not so pretty if an engine quits. Roads with lots of traffic, lights, signs and so forth are grim choice. Out West, with wide right-of-ways, roads are great runways; just avoid culverts and curves, as that’s where signs and reflector posts go, and keep a sharp eye for any along the straights. If at all possible, land down the centerline, for wingtip clearance; don’t depend on it, so land between stakes and signs. Interstates can be good open spaces, but we know vehicles are plenty, are going fast, and least expect an airplane to land in front of them. Keep an eye out and plan accordingly. The benefit to an off-airport landing for avoidance of bad weather is that we’ll most likely be under power, have time to check things out, and maybe even make a quick low pass, as long as we don’t get sidetracked and spin in on the go around. Check carefully for obstructions, especially wires that may be concealed by trees, or be suspicious on seeing a telephone pole in a field; look for where wires connected to the pole pass across the field. Then, when you decide it’s time to land, do a proper and normal pattern: downwind, base, and final, all the while looking the field over for any further obstructions and rough surface that may become apparent as you get lower. Again, landing away from an airport in a field may be far safer than trying to work along in bad visibility and ceiling with the ground getting closer and the visibility ahead poorer. It can also be an out if we’re boxed in with thunderstorms or can’t outrun a squall line; in lieu of flying into such violent conditions,

especially VFR. In any event, landing in fields can be a far better alternative. Just don’t rush; stay cool and fly the airplane!

Where Is the Wind? Flying VFR, a pilot must be constantly aware of the wind, where it’s coming from, and how fast. In mountains, it’s helpful to realize that there will be more cloud on the upwind side of a ridge, and it doesn’t have to be a steep ridge. Even a gently sloping hill will give enough lift to the air to cause clouds. This somewhat reviews part of Chapter 11 , but we feel it’s worth it. On the downwind side, there will be downdrafts, and if the wind is strong, they’ll also be strong and turbulent. One needs to be flying in clear air, with good visibility, when wrestling downdrafts, so fly a fair distance from the mountain on the downwind side, where it will be clear or the ceiling will be higher. The airplane’s altitude should be above that of the range, if clouds will allow. The worst downdraft spillage on the downwind side of a ridge will occur at or below the level of the mountains or perhaps a little higher than the ridge, but not by much. There are areas where winds converge. This can cause turbulence and, sometimes, enough lifting to make clouds. If the wind is flowing down a valley and there’s a ridge in the valley, the wind will be split as it goes around this ridge. On the downwind side, the wind comes back together again, pushing against itself, creating an area of convergence and vortex. We have to consider those cuts in mountains, ridges oriented in different directions, peaks, and valleys all cause moving air to tumble and eddy in very irregular ways that are difficult to visualize. Wind coming down one valley and flowing into another will give turbulence and convergence. Caution is called for in mountainous areas, especially in areas where the mountains are arranged in hodgepodge fashion and not neatly lined up. There can be areas of cloud in unexpected locations because of mountain irregularities.

Near Cities If one is approaching an industrial area, town or city, a detour around the upwind side will give better visibility. This rule will often apply to bodies of water, too, where a light wind can give more fog and lower visibility on the downwind side.

Summertime While summer is a nice time to fly, it sometimes brings serious visibility problems to the VFR pilot. The sky may be cloudless, but the summer haze makes a crosscountry flight by map reading a difficult chore. This is an especially good time to be on the upwind side of cities, because the polluted air mixes with the haze and

makes the visibility much worse. Even if using an electronic sectional chart display, with moving-map position of our aircraft, we have to look out and relate the map to what’s down on the ground, searching for places we might go should an engine failure or similar fix suddenly occur. And, of course, hazy weather makes spotting other aircraft more of a challenge. An inversion causes all this, where the temperature aloft suddenly gets warmer. The hazy air can rise no higher than this altitude where the temperature increases. Climbing, we come out of the mass of glop and find ourselves in clean, clear air with miles and miles of visibility. Looking down, however, we see almost nothing, and navigating is difficult. An occasional river glints through the smaze, the white ribbon of a highway, a piece of a mountain. It’s all difficult to put together in the jigsaw puzzle of map reading. If we are VOR, ADF, or GPS equipped—especially with a GPS sectional chart moving-map display—we can use this equipment for navigation and, by looking at the occasional clues below, know where we are, where that nearest airport is, and what the countryside really is like, should we need to descend or find a place to quickly land, say from an engine failure or similar dire mess. Without these navigation systems helping us, it’s a job of super concentration, and often it’s worthwhile to swallow pride and fly a slightly longer course to follow a visible highway or other geographical feature.

Thunderstorms and VFR Summer brings thunderstorms, and depending on where we are flying, reduced visibility in summer’s haze makes them difficult to see. On top of the haze level, the big cauliflower clouds can be seen clearly and are easily avoided. Down low, in the smaze, one doesn’t know if the bad visibility is smaze or darkness from a nearby thunderstorm. Flying high, above the haze and ducking thunderstorms, a pilot needs to also watch below, because clouds may sneak underneath us if we’re close to a storm. To avoid thunderstorms, we need to see them. For VFR flight, this usually means visually, but radar and lightning detection equipment can help, as long as we remember our VFR limitations. This process begins before takeoff, during our weather briefing. With all the sources of NEXRAD, we can usually get some sort of look at thunderstorm activity, so we can plan our VFR far around any convective weather areas. If we are without radar, a call to the FSS can give us radar data, as well as Convective SIGMETs. We need to ask plainly for what their radar is showing, as a supplement to the broader look by Convective SIGMETs, but once we have this data and are underway, we’re remembering data that is now untimely. We use this information for avoiding the areas, not for squiggling through them. Once airborne, Flight Watch, FSS, or ATC may be able to help us

with radar data. However, ATC may not always be able to do so, because of traffic demands, and Flight Watch is again our vision from their words, rather than a direct picture. So we don’t take off planning to fly through thunderstorm areas by getting help from the ground. If we do have NEXRAD, lightning detection, and/or airborne radar, because we’re VFR, we use this information to totally avoid the area. Thunderstorms, at best, are things to avoid. This is especially true for the VFR pilot. A good look at the weather before flight will show if thunderstorms are going to be of the air-mass types or ones caused by frontal activity, and therefore, how to plan around them. Air-mass storms are scattered enough to tour around, staying in the clear. If they are frontal storms, the VFR pilot’s place is on the ground! Ducking around thunderstorms means staying out of them, and it also means giving them a wide berth. Turbulence outside a storm can be as rough as that inside. There’s also danger of hail falling from the high, overhanging, anvil portion of the cloud into clear air. A general rule is not to fly over lower clouds or under higher clouds in the immediate vicinity of thunderstorms. While weaving around, it’s best to keep working upwind of the storm, because most action is on the downwind portion. Also, an eventual return to course will be shorter with faster ground speed. Compass headings should be noted: knowing the time on various headings is a help in guesstimating how far off course one may be going and which way. Obviously, a GPS makes this scenario a lot easier, but we emphasize still keeping this mental picture of things. This is our redundant system when depending on electronics. An important point about headings is that if one seems forced to keep working in one direction, say southwest, and is unable to work back northwest because of storms, it’s obvious that one is making a big end run. This means that the storms are pretty well lined up, and there isn’t any clear path on the desired course. It may be a front, a prefrontal line squall developing, or a bunch of air-mass thunderstorms that have lined up in a pseudo-front. It’s time to land, or turn around and go back. A pilot must consider that the storms being circumnavigated may be right over the destination. If so, it may be necessary to go elsewhere or fly around out in the clear until the storm drifts away. This means there must be enough fuel on board and daylight remaining. Flying VFR at night around thunderstorms isn’t a recommended procedure; it is very difficult to see where the clouds are located, and in early evening, the storms are probably at their worst, with the clouds more extensive. Even with NEXRAD, we need remember that what’s on radar is rain. It does not show surrounding clouds, and we will not see them in the dark of night, until suddenly everything disappears, and we are on instruments! One simply should not be out there unless instrument-qualified; it’s an instrument environment.

A point to remember about air-mass thunderstorms is that they occur mostly in the afternoon. If a pilot gets an early-morning start, it’s possible to avoid a lot of air-mass thunderstorm activity. Depending on our journey’s length, we may be able to reach the destination before afternoon storms have built up and covered a wide area that is difficult to get through. There is much more to be said about thunderstorms, which we’ll do in the chapter on thunderstorms. But right here, while talking about VFR, these points are important, and the most important of them is to stay in the clear, always having a wide avenue handy for hasty retreat.

VFR on Top Flying VFR doesn’t mean one has to stay under clouds. If there are scattered clouds with a top that’s not too high, it’s better to be on top in clear air than down in smazy air worrying along in reduced visibility. It’s also more pleasant, because the air is smooth and cool. We must be certain, however, that those scattered clouds stay scattered and don’t become broken or overcast. A non–instrument qualified pilot must be able to come down without going through clouds. A good study of weather before takeoff can assure the pilot that the flight isn’t toward frontal conditions or into mountainous areas, where clouds tend to be broken and at times overcast instead of scattered with higher tops. Also, over higher terrain, cloud tops can rise, and suddenly one is stuck with cloud tops just below our cruise altitude, and the inability or prudence of climbing higher due to aircraft performance or pilot physiological limits. Even if we are legal to file an IFR flight plan, if the sky is cold enough, we’ll be entering IFR into ice potential; as discussed more in the chapter on icing, if the temperatures are freezing to the ground or our minimum en route altitude, we’re stuck in any ice without potential escape. VFR on top, for the non–IFR rated pilot, becomes a trapped situation when issues occur, such as an engine problem, something starts smoking, and so forth. However, all said and done, if the clouds are scattered, there’s no sense in sitting down low working and worrying unnecessarily.

VFR on top, in northwestern Montana. Nice VFR at 11,500 feet, but the 2,500foot valley floor, with landable fields and some airports, was fogged in. That lasted about 60 miles, or a half hour of flying; it was clear either side into skinny, mostly treed valleys. There were a couple of choices; one was turning back and waiting for it to clear, but with the concern that the dissipating fog would provide lifted moisture from the warming day, risking a cumulus-clogged valley. The other choice was to go, and for a half hour hope the engine didn’t quit—or that anything else would happen that required a quick landing. What is your decision? (PHOTO BY ROBERT O. BUCK)

Using Electronics When VFR Today, most airplanes are well equipped as to communications, navigation and weather data, much of which comes from some sort of GPS-based navigation system, even if simply pocket sized and portable. So now, a simply equipped VFR-aircraft can, with a good aircraft radio, transponder and GPS unit offering data-link capability, have excellent communication, navigation and weather information ability, far in excess of any earlier generation jet aircraft; even if a 70 mile per hour Piper Cub. The VFR pilot can use this equipment as an extremely accurate aid to navigation, communicate with ATC, and of course, if so equipped with data link, keep an eye on the weather—be it text reports or digital images; and all on a simple VFR flight. A big benefit of this data-link weather information is through images of radar and satellite, as well as station reports and warning information, the VFR pilot now has a top-shelf “big-picture” look at their flight.

This allows end-runs of weather which increases utility of general aviation, even if just VFR. This is also good training for the future when working towards an instrument rating. There are three basic parts to this related instrument capability. One is knowing how to fly by instruments, keeping the airplane under control without outside visual reference. The second part is navigation, handling radio communications for ATC purposes, and obtaining weather information. The third, if our airplane is equipped with high-end electronics is managing all these systems for a functional flight. The pilot who cannot fly instruments can nevertheless learn and develop proficiency in navigation, ATC communications, and weather-gathering, and yes, managing it all, while flying VFR. We practice obtaining weather information by using the radio to contact Flight Watch and the FSS, listen to HIWAS broadcasts, as well as to use any data link information we have mentioned above. We learn where we can get this information, on what frequencies and from which electronic sources. We can navigate using our full house of equipment, but we should also use sectional charts, time and distance, following a track, crossing checkpoints, and checking speed, using a handheld computer. This teaches us how navigation works and gives us a sixth-sense for what’s really happening, which is a very important asset, when using the latest electronic navigation. I (ROB) have seen this countless times, and also am concerned of a new generation of pilots who have never been taught navigation without some sort of augmented assistance. Also, having raw old-school ability makes it non-event when the fancy stuff fails and we’re far from home. We should file VFR flight plans and keep in touch with Flight Service Stations or Flight Watch as mentioned above, which should include obtaining the altimeter setting of the nearest airport, so height is correct, giving an estimate for destination, and offering PIREPs of our flight conditions, helping other pilots. These efforts, along with using our radios for airport altimeter and sky condition information from ASOS, AWOS, and ATIS broadcasts from airports, by obtaining the frequencies on our VFR charts, keeps us current with the system in lieu of flying in isolation through data link information and being disconnected from the total environment. If VFR pilots do all these things, they will develop a facility that will be useful in instrument flying. Practicing and learning VFR will make passing the instrument test easier and, most important, will mean that when starting to use a newly acquired instrument ticket, things will be familiar, useful, and safer, sooner. There’s a lot of value, present and future, in using many IFR procedures while flying VFR, those within legal bounds, of course.

Without Radio

Pilots without radio can fly VFR and certain types of weather, too. I (RNB) flew my first seven years without radio of any kind, and this included flights coast to coast, to Mexico, and to Cuba. That was admittedly in the 1930s, but in 2010, when the next generation of family flew across the United States and back in a Cessna 170, had we chosen not to fly into radio-required airspace areas, we could have gone without radio, having a safe and great time. Ironically, one can have, through battery-powered GPS and data link, all those benefits of excellent weather data, radar, satellite, lightning data, and needle-threading navigation without having radio communication; but that’s hypothetical, and a nicely rigged handheld radio and headset combination completes the basics; and admittedly is more prudent in the long run, especially in our ever-increasing air traffic world. However, if we’re flying old school for some reason, without the availability of en route information for navigation or communication, the preflight study must be thorough. In-flight observation of clouds and their type, visibility, wind, and any other phenomena that may signal changing conditions becomes a constant and crafty task. Occasionally, it may be necessary to land and check just what the heck is going on. But the game is interesting, and a pilot may learn much, so that someday, when instruments and radio are available, that pilot will be a better weather pilot. Two points not to be forgotten when flying VFR are the legal minimums and where one can and cannot go. Like all minimums, they should not be our only guide; there are times when it isn’t comfortable flying, even though legal minimums exist. Comfortable means just that. When we are a little tense, wishing things were better, our psyche may be telling us it’s time to quit, VFR minimums or not. While flying VFR, there is a strong responsibility to look for other aircraft. Often VFR flying is putting us where many IFR aircraft are flying: on top, sometimes between layers, in traffic areas where instrument approaches may be coming out of a legal VFR ceiling or departures popping out the tops of clouds we’re flying over. Some of the IFR pilots, unfortunately, have a mistaken idea that because they are in the system, on a flight plan, they are protected from all aircraft. Well, they aren’t protected from VFR traffic in many places, and this puts a burden on the VFR pilot to keep alert, looking for that other aircraft that could spoil your day. Oh! what did we do with that foggy valley in Montana pictured earlier in the chapter? We went, figuring an emergency landing to a side valley would be slow and workable in the lighter wing-loaded 170. We cleared the fog in about 20 minutes, and it was clear all the way to our destination of Helena, Montana. So now, on to the pilot with an instrument rating, a piece of paper that doesn’t necessarily mean one is a weather pilot because, at first, it’s only a learner’s permit.

13 About Keeping Proficient Flying Instruments We may have an instrument rating, but unless we stay proficient, the rating isn’t any good. In 1970, when this book was first published, that proficiency was proving we could adequately hand-fly the aircraft on instruments, as well as dealing with avionics and navigation. Today, we fly to the same requirements, but have added the need to demonstrate understanding and management of any advanced systems. Sometimes called Technically Advanced Aircraft (TAA), this reflects those sporting combinations of any or all technologies such as Electronic Flight Instrument Systems (EFIS), GPS-based programmable navigation, informational displays, advanced autopilots and so forth. For years, it was a common event to fly IFR without autopilots in single-and twin-engine aircraft—all hand-flown. If one had an autopilot, it was pretty basic. The idea of automation that could follow programmed navigation was a rare concept and limited to aircraft such as the just-introduced Boeing 747. Electronic displays, as we have today, showing fully programmed routes with autopilots following both horizontal and vertical path, were still a backroom concept— especially for light aircraft. Even airliners had their fair share of hand-flying, and not just takeoffs and landings. In the 1960s, as a young teenager sitting jumpseat on several Boeing 707 Atlantic crossings, I (ROB) witnessed two with inoperative autopilots. Yes, the two pilots hand-flew the whole trip of nearly eight hours, swapping off each half hour; at cruise, where jets are sensitive to fly by hand, the altimeters hardly budged. As a budding young pilot, it was both humbling and impressive to watch. However, all is not lost. Even now in 2013 there are still quite a few general aviation pilots doing a fine job flying instruments without autopilots, or maybe with just a simple, single-axis one. There are a couple of important aspects that make this work. First, we should have instrumentation and avionics that are not complicated or of high workload. Second, we need to be proficient at flying instruments. Today, this concept can be overshadowed by all the buzz of technically advanced aircraft. Yet basic instrument flying teaches golden lessons that will always serve us well, especially when one suffers failure from an allencompassing electronic flight system. As alluded to in previous chapter, there is a potential misconception that once one graduates to these highly automated

electronic aircraft, redundancy and reliability allows less necessity for raw flying ability versus more proficiency with system management. The truth is, they are both are required, so our work is cut out for us. One of the biggest challenges to a pilot’s instrument flying proficiency is overreliance from even basic autopilots. In all fairness, this problem came along far before technically advanced aircraft, as automatic flight has been around for a long time. However, we realize today’s programmable technically advanced systems, when fully used, really demand autopilots; especially if we fly them single-pilot. The main reason is they defeat rule number one above: they are complex and demand a high workload. So, we have a conundrum of pilots needing to stay proficient with hand-flying, while flying aircraft that really should be flown with automation. There is also a trend toward integrating autopilots and flight scenarios into initial flight training, instead of solely concentrating on learning basic flying skills. Our experience shows that learning the flying skills first, and then applying these to advanced avionics and scenarios, creates a more well-rounded and capable pilot. Either way, these days a good instrument proficiency check, especially in technically advanced aircraft, is an integral process of both adequate (although stellar is better) hand-flying as well as managing all the electronics, automation, and scenarios. The reason we need adequate hand-flying skills is simple. Even very reliable and redundant equipment will break—we just never know when or on whose watch. To put it bluntly, hand-flown instrument proficiency is the lowest common denominator of skill that will save our bacon, if we lose the fancy stuff but still have that bare minimum of standby gyro instruments to keep us upright and bring us home. Ballistic parachutes, in our opinion, don’t count for this scenario, as they should not be there to compensate for inadequate pilot ability. So this chapter discusses keeping pilots as pilots, whether our aircraft is technically advanced or not, and at the end of a leash that is held by the pilot, not the other way around. Although we have been discussing instrument flying proficiency, let’s throw in a little zinger for VFR pilots. When we fly VFR, with technically advanced aircraft, the programming and monitoring is the same as if we’re flying instruments; namely, our heads and eyes are inside, taking care of all the system management and orchestration. If anything, except a minimum of electronics, this also means we should probably be on an autopilot. So here we go again, we’re not keeping current with hand-flying, and are not adequately looking outside for other aircraft and, in the case of VFR, the ground! So how do we keep sharp? Professional aviation uses simulators to check pilots at regular intervals, in what most of us know as recurrent training. In aircraft of complexity, this is imperative. The simulators allow more thorough and diverse training than one can achieve in a live aircraft, let alone being far safer. It is also a lot less expensive. Professional pilots are also observed on actual flights by check pilots, to see how they handle not only flying but also management of

the entire job. This level of training is finally filtering into personal general aviation, including light aircraft. It is gratifying to see this discipline in place, especially as an important compliment to the high-performance, new-generation light aircraft, and their superb but task-extensive technically advanced instrumentation. Recurrent training is valid whether we are flying the fanciest equipment or a light aircraft with good old round-dial, basic instrumentation and navigation ability. There are many fine organizations that provide this training. Some are manufacturer-based or aircraft-specific, which is very important in properly qualifying new customers before they fly away with their shiny new airplanes. The more advanced the airplane and/or avionics, the more important it is to consider predelivery training. Then, hopefully, pilots return for regular recurrent training, with every six months a popular time frame. It’s worth noting this is often required by insurance companies, for pilots of technically advanced aircraft. Both check flights and some form of recurrent training are a very smart idea. And often there are professionals right at home, as well as ways we can stay at top level and test our own abilities. Our professional at home is a good flight instructor, and for many pilots a fine method of staying current; whether self-imposed proficiency or that required by regulation. Instructors can pick up on undesirable habit patterns and present us with abnormal events of both aircraft and instrument flying that keep us sharp and safe. If at all possible, it is very important that we receive our checking and/or instruction in the actual aircraft we will fly, especially if it is technically advanced and a custom, retrofitted electronic system. Where in the past round-dials, radios, and VOR receivers were pretty much just that, the many electronic flight system vendors and combinations of installation can make each aircraft and its system unique, in both operation and capability. Another venue is flying a simulator at a flight school, where again we have the benefit of an instructor’s mentorship to allow a professional training environment. These simulators do not have to be highly complex, device-specific arrangements, although those that are offer a superb environment. There are many excellent computer-based systems with flat-screen display over instrument panel and controls; sometimes it’s an understandable matter of cost. Because a great deal of instrument training deals with orchestrating instrument procedures, flying approaches, and related abnormal aircraft issues, as well as time to practice handflown operation which also improves our instrument scan, these simulators do a great job. At home, computer-based flight simulators offer a lot of similarity to what we have just mentioned, but of course, without the professional mentorship and follow-through with the training experience. When we don’t have time or resources to do actual flying or extensive simulation, these home computer-based simulators still improve our ability to handle complex ATC procedures and

approaches as well as help us stay proficient with hand-flying and our scan. This is an especially good combination if our actual flying normally has the autopilot doing much of the work. In the 1970s, we had a spell of time without much instrument flying. We used a very simple desktop simulator, with its almost toylike appearance making us skeptical. However, after several hours of flying and procedures, it really sharpened instrument skills, which was proven when we finally got back in the air. It was also a lot cheaper than grinding around in a real airplane. It continued to be helpful during those bad days of Vermont winter, when we were not flying very often. We can also use some simulation systems to keep current with minimum IFR currency, as dictated by FARs.

An excellent desktop simulator that is FAA-approved for partial instrument training and recurrency. Not only is it an excellent way to stay current with handflying skills, but its modern EFIS instrument display allows both initial familiarization and a refresher to these excellent, yet task-focused, systems. (PHOTO BY ROBERT O. BUCK. COURTESY OF VERMONT FLIGHT ACADEMY, INC., AND REDBIRD FLIGHT SIMULATIONS, INC.)

The instrument panel and vision system of an economical yet extremely capable motion simulator that can provide a large portion of one’s FAA-approved instrument training. It consists of a little cab with seats for pilot and instructor, the instruments, controls and vision system offering an excellent instruction platform with a valid sense of motion. (PHOTO BY ROBERT O. BUCK; AND COURTESY OF VERMONT FLIGHT ACADEMY, INC., AND REDBIRD FLIGHT SIMULATIONS, INC.) In relation to technically advanced aircraft, simulation, or at least electronic media recurrent training, is a natural fit and arguably required; if not by regulation, at least by common sense. Being out of currency with these systems not only reduces their utility, it can create a degraded flight environment, as we tend to spend excessive time fiddling with electronic system protocol and management, because we’re rusty with the task. This keeps us heads-down in the cockpit, with all the commensurate risks, not the least of which can be loss of our aircraft’s primary control. This world of media training is taking serious hold, even to the extent that many professional aviation operations, including airlines, are going the way of home computer–based material to cover ground school aspects of training, leaving simulation of procedures and flying as the majority of their in-house training. Of course, this media need not be limited to just aircraft training. There are many diverse media tutorials that can keep us sharp with things such as GPS navigation, ATC practices, and yes, weather.

The ultimate of simulation. A Boeing 777 simulator, it’s an identical cockpit replica, with perfect duplication of operation, including extremely realistic outside vision and motion. These simulators allow all training from first lesson to type-rating, and the pilot’s initial airplane flight on a revenue trip with a checkCaptain. In this image, as the pilots set up their instruments and systems, the instructor—in this case a qualified captain—prepares his challenges. (PHOTO BY ROBERT O. BUCK)

Practice The first thing to consider is how we fly every day. We need to fly precisely, practicing in good weather or bad. If we fly as though an FAA inspector was looking over our shoulders, we’ll fight off complacency and sloppiness. Surprisingly, trying to fly the best possible way will finally become our normal flying character, making us better pilots all the time. This means holding altitudes and headings as closely as possible, flying precise airspeeds in climb and descent, and making corrections smoothly and exactly. If we do these things, they become a habit. An important part of this is to use an instrument approach as much as possible, every time there’s one available for the runway we’re landing on, good weather or bad. The more practice, the better. In today’s world of technically advanced aircraft, we’ll alternate between flying them manually and automated. That way, we stay sharp not only with hand-flown approaches, but also with the complexities of programming and monitoring the automatic ones. The reason for this is obvious—the autopilot is going to take us where it’s told to go, and being close to the ground gives us little if any time to deal with mistakes and quandaries.

We should also throw in a missed approach now and then, as we don’t often do them, but when they are needed we’re low and slow and must quickly transition to climb; the margins are slim. Statistics show missed approaches, along with takeoffs and landings, to be a very weak area of flying skills—in other words, too many accidents occur in these areas. That says something about needing to keep basic flying skills sharp, because these phases of flight are usually hand-flown. These practice approaches, depending on our currency and ability, are usually best flown in weather that is better than actual IFR minimums. However, we play the game as if it were real, including all the normal approach review, briefings, and system setup, then follow all the appropriate protocol. Finally, in the real world of low weather, if we have the equipment, we’ll fly that approach coupled to the autopilot, allowing full attention to monitor the whole event and with the confidence that if we must assume manual control, it will be workable and safe. It is also important to sneak up on actual minimums, setting them higher for a variety of reasons, such as being a new pilot, not current, having new equipment, or maybe not feeling so sharp that day. However, when we practice approaches in better weather as mentioned above, we should fly the approaches to actual minimums. This helps a neophyte lower those higher minimums, but either way, if we’re stuck with the real deal, it’s a more doable task. As a side note, when an airline captain first checks out in the position, or in a new aircraft, regulations require instrument minimums to be increased, sometimes for as long as 100 hours, depending on the type of approach. On one side, we tout the necessity of manual practice, but on the other we say doing so in technically advanced airplane can be extremely demanding. Fiddling with buttons and knobs while hand-flying is not a good combination. One way to help this issue is to use a spotter pilot. Obviously this is a no-brainer, and is also regulation, if we practice IFR by flying “under the hood,” which duplicates instrument conditions. Another help is to have as much programming as possible taken care of before takeoff, or if in the air, as a prelude to disconnecting the autopilot for the practice session. If at any time in our make-believe world real problems occur, we should immediately discontinue the training and revert to normal operation. However, in the real world, if we have a real problem that compromises airplane or equipment, we need to advise ATC of our condition, maybe request things like vectors, direct routings, a diversion to better weather, or even land to get the equipment fixed or at least wait for better situation. When flying ILS approaches on a VFR basis, it’s interesting to see where the ILS takes us. One learns about bends in both localizer and glideslope when flying an ILS, or quirks of other approaches, and what sort of terrain they thread us through. It gives us a chance to see what various altitudes and terrain clearances look like along the approach path. We can learn how far “off course” it’s possible to be at minimum altitude in order to have enough room to turn and safely make it

to the runway—without aerobatic maneuvers close to the ground. And if we want to really see what a circling approach is like in reference to terrain, try one at minimums when the airport is clear and quiet; it can be an eye-opener. GPS approaches tend to be pragmatically consistent, whereas ILSs and VORs act in different ways. They have their own characteristic bends; they have personality. Also, glideslopes are not good all the way to the ground. Usually, their signals become useless at some altitude near 100 feet. I’ve found that this altitude varies with individual glideslopes; some are good down to 80 feet, while others “come apart” at 150 feet. Category II and III runways obviously have excellent ILSs, but that is predicated on having no aircraft within the ILS critical area. When conditions are better than Cat II/III, aircraft usually taxi closer to the runway, which can add interference to lower ILS accuracy; so, if we’re practicing a low approach in better weather, that ILS may wander or become inaccurate before we reach minimums. So while practicing ILS approaches, we can see where the glideslopes, especially at runways we frequently use lose their accuracy. All this can be handy knowledge on some stormy night when we really have to shoot a tough one. It’s good to know the peculiarities of each approach we normally use. Proficiency is a matter of practice, and that is a matter of doing. We really should practice these situations in all phases of flight; not just approaches, takeoffs, landings and go-arounds, but also climbs and descents, where we need be dynamic in three dimensions, versus just grinding along straight and level. With automation in general aviation at levels that mirror large aircraft, these different venues of flying are closer than ever before in emulating the quandary of staying proficient. In professional flying, staying sharp with “stick and rudder” skills isn’t easy, with occasional hand-flying and 6-month simulator checks the only way we can stay sharp. Recent statistics of a professional flight operation showed the average hand-flown time per flight of literally just minutes; we’ll brashly say this is typical throughout the whole industry, including personal technically advanced aircraft! With today’s ultra-long haul airline flights having multiple crews for rest regulations, just staying legal with landing currency is a big problem; trips to the simulator just to make three take offs and landings for maintaining currency are not uncommon. The pilots we’ve seen that seem to have trouble on instrument checks are the ones who get in the habit of doing only the necessary flying and no more. If it’s VFR, they just go in and land. They don’t make use of flying’s opportunities. We’ve seen pilots have trouble and then, when awakened by the jolt of a down check, get to work and come back to top-level proficiency. Generally, one jolt lasts a lifetime. It not only raises the ugly idea that maybe we shouldn’t be doing this flying routine, but even worse, if we’re professional pilots, we could find ourselves without work. It’s also a real injury to one’s pride.

Managing Flying Workload When flying instruments, especially when hand-flying, we’re balancing a lot of balls. The ability to fly the airplane, manage all the gadgets, and deal with weather, ATC, and so forth can be overwhelming. Throw in an abnormal system problem, and things can turn into a real goat-roping event. A real trick to relieving some of this chaos is not to press ourselves to function faster with more multitasking, but instead to prioritize what’s important and what we can put aside for later, or maybe throw out altogether. This is not knowledge that can be simply taught; it comes from good instruction, practice, and experience. When we get overstressed, it is amazing the stuff we’ll do while at the same time having no clue we are doing it. Video cameras in simulators were a humbling but effective concept, where the lesson was to load up the crew and see what they did. We’d swear we didn’t do this or that, but by gosh, we did! Our career dovetailed with development of what was called Line-Orientated Flight Training (LOFT ), which is also scenario training. It’s not just about learning to do things related to flying, but also helps us learn about ourselves and how we function in the flying environment. This, of course, was an adjunct for pilots who’d spent many years first developing good basic flying habits. In due respect, a fair portion of old-timers kind of figured this out long before LOFT. In 1969, while seeking an instrument rating and well before my aviation career, I (ROB) met a marvelous man named Charlie Gress. Retired from Douglas Aircraft, he had run the instrument training that kept the Douglas flight department up to snuff. Charlie’s retirement job was operating a little instrument flying school at Santa Monica Airport in California. However, he did not use airplanes; instead, he used two WWII–era Link Trainers. Their stubby and boxy little wooden fuselages, with one seat covered by a wooden hood, sat about four feet off the ground on a pedestal in which pneumatic bellows hissed the ersatz motion of these humbling little trainers. With a set of real aircraft instruments, controls, and lighting from the Link’s time period, you sat in the aroma of wood, glue, varnish, leather, and oil for mechanisms, feeling about 1943. This was no toy operation; these things trained an era of superb aviators, and Charlie was an old-school master with old-school expectations. We started with the Link sporting a basic panel of turn and bank, compass, ADF, and so forth, practicing standard instrument maneuvers. Then we’d go to the fancy Link with the artificial horizon, directional gyro, VOR with ILS, and yes, another well-used ADF. Sadly, we just missed the era of low-frequency, range navigation. And before a session was over, to that aroma of wood, leather, and oil, we added a lot of sweat. So in my aviation life the concept of reducing cockpit chaos, by prioritization of what’s important, began from a few of Charlie’s rules. One was not to write down any clearances and the same for figuring holding patterns: listen, think and remember. Another insisted anything requiring timing to navigation was done in

our heads, remembering basics like a 360° standard turn took two minutes, holding legs were one minute, and we cruised two miles per minute. You threw in descent rates for altitude clearances. Lastly, the big one was to never, but never, distract ourselves by picking up that magnificent WWII–style microphone and talk during climb, descents, or turns. He usually arranged things so we’d not have long periods of time from his mock ATC commands and our communication, but the idea was to fly the airplane first, navigate second, and talk third. As a side note, if you tried sneaking that mic off its hook before you were level, somehow Charlie knew. His monotone and disciplining voice would say: “Put the microphone down and flyyyy the airplane!” How he knew remains a mystery, but more importantly, Charlie taught as much confidence as he did the gift of old-school instrument flying basics. Obviously, in these later years, especially with boom mics and good autopilots, we can do a fair amount more in other than straight and level flight, but certainly not without keeping an eye on those primary flight instruments; autopilot or not. Also, in reality to today’s complex ATC world, it’s really necessary to write down and understand all clearances; but Charlie taught one to think! (And those years with Charlie were over forty years ago, when young enough to have a memory.) Still, it’s important to focus on seeing our airplane capture an altitude, course, complete a turn, or confirm a mode-capture on an EFIS display, and so forth, before fiddling with something or worrying about ATC. This is sometimes difficult when there is something creating an issue that can suck our eyes and brains away from basic flying. Throughout a fortunate and safe aviation career, whenever things got hairy, you could hear Charlie saying “Flyyyy the airplane.” Even in fancy equipped, high-performance airplanes, his lessons were never outdated.

Self-Checking We are always interested in how good we are, and what sort of situation we can handle. Well, in the absence of a check pilot, let’s be our own check pilot. And yes, this is hand-flying! Because we will be flying under the hood, the first thing we need is someone to ride along who will look out for traffic. That person must also be able to recover the airplane, if we don’t fly instruments so well and it gets out of control. Two pilot friends can ride for each other and learn a lot in the process. Once in the air and at a good altitude, say 4,000 feet or above, put on the hood that prevents us from looking outside. We’ll fly these following exercises on the primary flight group: needle-ball or turn coordinator, airspeed, VSI, and a wet compass. If our backup gyro is an attitude indicator that will obviously be what we’ll use, but the rest is the same except many glass cockpits don’t have a VSI for backup. That’s where we need to know what attitude and power setting gives “X”

speed and rate of climb or descent, or count seconds while reading the altimeter. The exercises should be done without any appreciable altitude loss, overshooting or undershooting altitudes when descent or climb is called for, nor any great airspeed fluctuations. Any indication that we don’t have the airplane under control or are unable to keep it from stalling or exceeding high-speed limits, means instruction and practice are needed before we do any instrument flying. Remember, we must be able to fly the lowest common denominator of instrumentation for an otherwise perfectly good airplane. All the good stuff could quit on our next instrument flight. So here we go: round-dial ADI and DG/HSIs get covered; glass panels go dark. We’re off to the rodeo! Here are the test maneuvers, under the hood, primary flight group: 1. Straight and level for 5 minutes. 2. Climb at 300 feet per minute, airspeed 50 percent above stall. Climb like this for 1,000 feet. Level off at an exact altitude. Then descend at 500 feet per minute, same airspeed, for 1,000 feet and level off at the altitude where we started the original climb. 3. Do a straight-ahead stall and recovery. A real stall! Not an approach to stall, but one that makes it shudder and shake and want to duck a wing. 4. A standard rate turn to right for 360°. Maintain altitude within 50 feet. Roll into one-needle-width turn to left for 360°. Hold altitude. 5. Stall from 30° banked turn. 6. Establish three-needle-width—or similar off the turn coordinator 1 turning to the left for 360°. Keep turning and start descent, allowing airspeed to build up to 30 percent above cruise indicated airspeed IAS. (Don’t exceed any limits.) Descend 1,000 feet. Stop descent, level off, and come out of turn. 7. Following the above, immediately roll into three-needle-width turn to right. Do one 360° turn and then climb in the turn at 70 percent above stall lAS for 1,000 feet. Level off and stop turn. If we can do all these things neatly and with precision, being a master of the situation all the time, we’re a pretty good instrument pilot.

With Full Instruments Now uncover the DG and horizon, reignite the glass panels and fly with a full panel. However, this is still all hand-flown—no autopilot, flight director, or augmenting indications on a PFD. Now we do the following exercises. They are to show the precision demanded when flying in a traffic area and executing an approach and go-around (missed approach). They should be done with great exactness: airspeeds within a few knots, altitudes exact and not varying over 50 feet, headings hit on roll-out within 3°. Here we go:

1. Straight and level. Hold exact heading and IAS. 2. Reduce speed to 50 percent above stall. No altitude gain or loss. 3. Reduce speed to 40 percent above stall. Turn 45° to right. No altitude change and hit new heading within 3° on roll-out. 4. Maintain the above speed and descend at 300 feet per minute. Turn left 170°. If we have a retractable landing gear, lower it. 5. Level off, lower flaps to landing configuration, reduce to approach speed. Hold this for 2 minutes. 6. In the above configuration, descend at 500 feet per minute to a preselected altitude 1,000 feet below. 7. At that altitude, do a go-around. (Tune a VOR to a new station, set in a different radial, select a waypoint, or do some other demanding task.) Turn left 90° as you do. Establish climb speed and clean up gear and flaps. Climb 1,000 feet and level off. These exercise maneuvers are to check our sharpness. They aren’t an instrument pilot’s final exam. They are simply something to go back to now and then for an appraisal. The degree of precision obtained tells us our capability. The maneuvers on the primary group are really designed to make certain we can keep out of, or recover from, a spiral condition with increasing airspeed and recover from a stall. We can vary these maneuvers and design more. The basic thing in the fullpanel maneuvers is to try and load ourselves up with all the things that might be required, and see whether they can be done with the precision demanded by the ATC system and, of course, safely. This means one needs the ability to change speeds while climbing or descending, turn to headings, lower flaps and gear, adjust rates of climb or descent, and hit altitudes and headings exactly. There’s also a requirement to remember these altitudes and headings and keep them after leveling off. One could do all these things and toss in an extra job of consulting charts and worrying about carburetor heat, as well as talking on the radio. It can be quite a load, and we’d better face the fact and be prepared to handle it, because that’s the kind of load one can encounter in the system. It is a handful for a neophyte instrument pilot, especially alone and without autopilot. We should check ourselves periodically—every few months. An honest selfappraisal is often more severe than a check pilot’s. This isn’t the place to kid ourselves; if we’re not up to snuff, we should practice more, or go back for help from a professional instructor, or both. A Clever Gift of Flying Basics When I (ROB) began flying as a teenager, it was in a wonderful little 85

horsepower Cessna 120—for no special reason, named Sam. It had two friendly seats, a tail wheel, and no flaps. Fun to fly, Sam made one learn to enjoy slipping an airplane, cruised a decent 100 mph, but was gutless enough to build humility at a short airport. My father also loved the little airplane, reminding him of his Monocoupe during the 1930’s. In his eyes, the only drawback was a basic VHF radio with VOR navigation. Such led him to emphatically tell me it was okay to talk on the radio when I had to, but leave that “Omni,” as he called it, alone until “later on.” Vague time frame, but I liked to fly—stick and rudder stuff—so didn’t think much about it. After my ever-patient and superb instructor, Jim Frankenfield, left me free to roam beyond local solo flights, I began exploring either side of the Delaware River, from Van Sant airport in eastern Pennsylvania. I was to use a map, and if lost, figure it out or go land somewhere—even if a farmer’s field, before running out of gas or getting stuck in bad weather. Pretty straightforward; I think Jim and my father were in cahoots. Yes, I occasionally fiddled with the VOR—probably just because my father said not to touch it—but mostly ignored it, because flying that nice handling 120 was more fun. What was happening, however, without gadgets to fiddle with, I looked out the window at weather, terrain, a place to go if the engine quit, and for other airplanes. It was shooting landings—sometimes of fair crosswind at Van Sant’s single grass runway—and don’t spin-in circling everyone’s home. Later cross country trips kept me thinking about where north was, how much fuel was needed, and what’s going on with the airplane and engine. Of course “Omni” came into the picture, as did different airplanes, a diversity of flying, and the process of gaining pilot ratings, including that instrument one. We also said a sad goodbye to Sam, as a fully equipped Cessna 182 came along that was festooned with the works, except for one thing—an autopilot. The instruments were plenty, capable, but simple round ones. This Cessna was also a marvelous airplane, and I flew it hundreds of hours, crossing the country three times, and like so many others of the era didn’t think too much about not having an autopilot. Decades later, just after retiring from the flying career, my father and I were talking about—what else—airplanes. He asked me what was most memorable in my career. The best flying had been with Air North’s Twin Otters out of Burlington, Vermont, then on the Shuttle out of La Guardia in New York; a favorite was hand-flying between Washington or Boston in the 727, during the quieter times of a day. That Boeing was fun to fly, the weather diverse, and the Shuttle was a fly’n operation! We talked about flying the later “electric-jets,” and how despite the fancy instruments you always had the itch to know if the airplane was working okay and aimed in the right direction. And that retirement flight’s last landing, kicking out the crab from the crosswind on 22L at JFK; I’d felt a flashback to Sam at Van Sant, and it was a fine landing. Then he said: “You

remember when I told you not to use the Omni in Sam, and there was no autopilot in the 182?” He and Jim had a plan and it was a very clever one.

1 . Three-needle-widths refers to older Turn and Bank instruments originally used by first author, in 1930’s. One needle-width was a standard rate turn of 3 ° per second. Three widths is three times standard rate or 9 ° per second/40 seconds for a 360° turn. For use of standby-ADI’s we recommend at least a 45 ° bank for this maneuver.

14 Thoughts on Flying Technically Advanced Aircraft Technically advanced aircraft (TAA ) are the new high bar for weather flying, and they are marvelous. However, to the uninitiated or poorly prepared, these aircraft and systems can be overwhelming. It’s not just about learning how to operate the equipment; it’s also about learning how we merge their huge quantity of information into our flying, and how these systems affect the pilot. So we need to make a disciplined investment of time and patience in learning how to fully use whatever flight instrumentation and automation we have, and do so before trying to use them in-flight! The learning curve can be steep, requiring our restraint as we climb that hill. This means that even after learning the buttons and programming, we tread carefully, developing experience in their use. Maybe it means more time with an instructor or simulator, even flying conservative day-VFR for a bit, despite the temptation to jump right into instrument flying—the home court where these technologies shine. So we take the time to learn our new equipment, but we’ll tell you flat out this book is not going to broach that huge subject; it’s too big, too rapidly changing, and frankly isn’t within the context of the book. Instead, our comments of this chapter are from personal use, as well as operational concepts that developed in early use of these systems, which became standards of procedure or helpful technique. There are many fine publications and media tutorials on operating electronic flight systems and automation—we recommend all you can get your hands on—but the most important are those specific to the equipment you use. This point is really important, especially with older aircraft retrofitted with electronic flight systems; each one can have minutely different but operationally influential variations. One publication that we consider to be highly recommended reading, and certainly neutral ground, is the FAA’s Advanced Avionics Handbook (FAA-H80836 ). There is a quote from the book that we feel is very worthy, its subject related to a fair amount of TAA incidents and accidents, in both personal and professional flying: “Many studies have demonstrated a natural tendency for pilots to sometimes drift out of the loop when placed in the passive role of supervising an FMS/ RNAV and autopilot.” 1 We can plug in any combination of

available technically advanced flight systems for FMS/RNAV, 2 so either way it’s the same idea. This “in the loop” situation is a big deal in the world of technically advanced aircraft. With these aircraft, we add a lot of stuff to the “loop,” both in system operation and information output. This increases the risk of becoming passive in a couple of dangerous areas. One towards less monitoring of basic flight parameters, due to excessive programming and function innate to these systems, which keeps us heads-down, hence not watching what the airplane is doing and where it is going. The other issue is because of this excessive programming and monitoring, we rely on autopilots; hence hand-flying skills deteriorate. When electronic flight instrumentation, programmed navigation, and advanced automation were synced together and first introduced with the airlines (and probably where the term “glass cockpit” began) professional training was necessary and helped, but there was a lot the industry didn’t know about the interface between pilot, airplane, and the glass cockpit; there was a fair amount of on-the-job training. Fortunately, having two experienced pilots with old-school flying sense usually meant someone finally said: “I’ll fly and you fiddle with the thing.” Either way, there was enough excitement to convince everyone that this new equipment was great, but could be distracting in ways never before experienced. Disciplined flying had a new meaning!

Single-Pilot Operation in a Two-Pilot World Whether in a single or two-pilot aircraft, the concept of operating a technically advanced cockpit is pretty much the same, and depending on how fancy your equipment is, technology has tightened the gap between small and large aircraft systems. The obvious benefit of a two-pilot operation is that extra set of eyes, which supposedly ensures someone is always tending to flying basics, including looking outside in visual conditions, but also very important is having redundancy for just about everything going on in the cockpit. Another more subtle advantage of a two-pilot cockpit is being able to observe how a multitude of pilots—and personalities—interact with the electronics, programming, and automation. With a good crew relationship, constructive suggestions or warnings are welcome and frankly necessary. The single pilot of a general aviation TAA operation obviously has their work cut out for them, and we admire the majority who do it well. No matter how you skin the fruit, an autopilot does not totally make up for a second pilot, so in single-pilot operation we need to keep our minds thinking and eyes busy—and not fixated for very long. That’s hard to do with longer tasks, such as extensive programming of technically advanced flight systems. This increases the reliance on autopilots, again reducing those hand-flying skills. And redundancy? There is none, so we better get it right.

Dependence on Augmented Indications As well as autopilots, some electronic flight instrument systems have a lot of augmenting indications in the instruments to assist the pilot with flight guidance. We like to call them “cues.” These cues think for us, by displaying computerprocessed information, derived from raw-data and aircraft inputs, as guidance cues on an EADI, EHSI, or PFD, as to where we should aim the airplane. Flight directors, trend indications, course “noodles” showing the projected path of our airplane, guidance boxes that lead us through a flight path, and so forth, are superbly done and most helpful. They are really helpful when we’re hand-flying the airplane, so when they fail, we’re back to basic instrument thinking, and obviously, if we’ve been overly dependent on cues, we have our hands full. Now let’s go a step further. We have a total failure of our electronic flight displays—all of them! Now we have to fly using the standby attitude indicator, airspeed, altimeter, and compass. Whether it’s an EFIS-equipped Cessna 172 or a Boeing 777, the situation is pretty much the same. The screens go dark and even in a simulator training situation, where in theory we can’t get hurt, that moment can be a dramatic transition period, depending on how sharp we are with basic instrument flying skills. We can’t dwell on the issue, but instead relax, as we decide the electronic screens are gone forever. Now it’s fly the standby ADI, using good old attitude and power (pitch + power = performance), with airspeed, altitude, and heading just for reference to confirm the airplane is doing what we want it to do. If we know those attitudes and power settings, it works fine and is actually kind of fun. Now, with the above lesson completed, we have a reversed and less traumatic situation. It’s an experienced analog instrument (round-dial) pilot new to flying a cockpit with a full electronic flight display, including all the extraneous electronic indications and cues. That old-school pilot initially tends to avoid all the fancy stuff by flying “through” all the cues and seeks out the raw data of attitude, airspeed, altitude, rate of climb, heading, and navigation information. Then they will add the extra “cue” information when time allows, understanding control of the aircraft comes first, with the cues and goodies just icing on the cake. As a side note, learning to read electronically displayed, tape-style instrument indications, such as airspeed and altimeter, we’ll find we must read the digital indication, instead of taking a quick glance at the needle position of a round-dial display. Yes, there are trend and “you’re there” indications, but that’s derived secondary data; the primary numbers are the real deal, especially if cues or the whole system goes south. Old-school pilots tend to have their eyes scanning around in search of some primary indication reference, even if subconsciously. Thinking again about cues as secondary information, let’s consider, as an example, the flight director, also mentioned in an earlier chapter; this could be displayed in an EADI, PFD, or a mechanical, round-dial ADI. We remember from

discussing equipment that the flight director is working off computer-derived input from primary navigation information, which is most helpful during instrument approaches. When using the flight director, we should always be taking a glance at the primary, raw data indications, confirming the flight director is commanding a flight path that follows the primary navigation; it doesn’t work the other way around. If there is any question, we ignore the flight director—or turn it off—and fly the accurate, raw data information.

Electronic Seduction Sometimes in the cyber world, it seems we risk beginning to function more like a computer, and less like a visceral, thinking human. A potentially lighthearted example could be approaching an airport and listening to the ASOS or AWOS weather, but not looking at the windsock. Then we make a brake-screeching landing in a good tailwind, because a thermal came through, swapping the wind. In days past, without ASOS and AWOS, you really had to look at the windsock or wind-tee at an uncontrolled airport, because few gave wind reports, other than those where Flight Service Stations provided airport advisory. But today’s world of taking data from inhuman electronics seems to develop a kind of seduction away from human thinking. On the other hand, this could really be serious, such as fixation on and/or belief in instrument cues or maybe an autopilot operation that is not going as planned. Rather than referencing raw-data indications, and either redirecting the autopilot with immediate success, or hand-flying to safety, buttons are pressed until the airplane loses control or hits the ground. Melodramatic? No, say the accident records. When we fly an aircraft with a totally integrated electronic flight system, sometimes folks don’t fully understand—or remember—that the aircraft flies fine without this full integration of programmed navigation, autopilot, and EFIS displays. This situation might be from initial training issues, or insufficient recurrent training, but can be aided by diversity in using the advanced aircraft’s systems; either automated or hand-flying, and of course dependent on operational prudence. I (ROB) distinctly remember my first jet check-out as a Boeing 737 copilot. A round-dial panel, nevertheless it had a very advanced autopilot. From the first simulator lesson, the process was to integrate the flight director operation, which used functions from the autopilot system. The curriculum was busy, and time for basic familiarization with the airplane’s flying characteristics was constantly overshadowed by inputs from the autopilot and flight director. Unless one already had a similar background, it was a training environment out of a fire hose. Fortunately, once out of training, many of the captains knew the issues and when the weather was good, encouraged us to practice hand-flying the “raw” airplane. It

was enjoyable, built confidence and made better pilots. Sometime later, when checking out in the 767, things had changed. With its fancy autopilot and now an FMS and electronic instruments, the first simulator session was configured with just an EADI, EHSI, and VOR/ILS. Then, after some air work, VOR navigation tracking and an ILS approach, the flight director, autopilot, and FMS interface were introduced individually. That cemented understanding of how the various electronics worked together, or could work independently, building confidence that the airplane was still an airplane, and not a device. Someone had listened to many suggestions. There are also varying opinions on training new pilots in this age of technically advanced aircraft. With the TAA environment, new curriculums at some flight schools, which have been carefully and professionally created, begin flying the airplane integrated with all the advanced equipment, as well as scenario-based training, pretty much right from the first flight. Others, however, still prefer students’ initial instruction and solos with only basic instruments and well-developed hand-flying skills, then add new technology after basic flying foundation is firm. This all circulates around the concern of developing pilots who are dependent on technically advanced aircraft systems, and lacking basic flying skills, as well as confidence to use them; they will always be needed, whether in abnormal situations, or just normal takeoffs, landings and go-around—which happens to be the most demanding phases of flight and is chalking up too many accidents. Another issue relates to pilots who were initially confident and capable handflying pilots, who turned rusty because they became over reliant on an aircraft’s advanced instrumentation and/or automation. This is something we’ve witnessed when airlines had mixed-technology fleets of aircraft, as pilots moved from advanced digital aircraft back to the older analog airplanes; these moves between different aircraft came from seniority progression allowing moving up in position; and more pay. We saw it not only as a check-airman, but also feeling the threat, and fighting it, in our own flying. The simple answer was to hand-fly as much as we could, and frankly on days off I’d find time to do some good basic general aviation flying; and personally I’d add some enjoyable sailplane flying. In technically advanced cockpits, even very capable pilots can get sucked into fiddling with unnecessary electronic function, and forgetting the basics; it’s usually worse when we get pressured. In remembering, from previous chapter, video cameras in simulators, a favored training event was to set the simulated flight onto an arrival and subsequent ILS approach. When close to the airport, the instructor issued a parallel runway change. Cleverly, enough time was given to do a quick review of the approach and set it up through the ILS receiver and EHSI, but not enough time to sanely set it up through FMS programming. With the plane usually on autopilot, what happened was two very experienced aviators often went heads-down into their flight bags for charts (these were the days before

electronic charts) and then heads over the other way to load the FMS. Usually someone suddenly had their brain light up and mentioned one of them ought to monitor the flying, but the deed was already done. The correct answer was, of course, have someone pay attention to monitoring the airplane flying on autopilot, while the other tuned and identified the ILS, set the EHSI to ILS mode, and then the approach was flown without FMS interface. Even the autopilot could couple and fly the approach just fine, not caring if the FMS was even there; the ILS just talks to the autopilot. It was a heck of a lesson and really helped tighten things up. Today, with GPS and LNAV/VNAV approaches, we do have to use programmed information, but the point is most airplanes can still be flown with controls and throttles only (thrust-levers to some), and we must always pay attention to the flying first. An interesting aspect of those distraction exercises was that we’d seen it numerous times before, well before the days of advanced electronic flight systems, in high-profile accidents from crews fiddling with systems or problems and ignoring the flying. Great emphasis was placed on these accidents, and it improved cockpit discipline. Then, when glass cockpit operations appeared, it was as though crews were seduced once again by this totally new distraction. We still have a lot to learn. There are more and more pilots who have only experienced flying with technically advanced aircraft; some with a full-house complement. Intrinsically, if these pilots initially learn with only the basic electronic flight instruments, no cues or autopilot, it’s similar to learning on round-dial instruments where they fly maneuvers from the same basic inputs, requiring the same “seat of the pants” thinking. It also means one becomes skilled with hand-flying. However, whether a pilot learns with full electronics and autopilots, or in later use becomes technically advanced dependent, they are equally hooked, and can become overreliant on automation. An example occurs when a problem develops with an aircraft flying on automation, no matter whether the problem is due to system failure or pilot-induced error. Those who are automatic-style pilots invariably try to fix the problem while the airplane stays on automation. More often than not, things get more screwed up, with situational awareness easily lost. Throw in automatic throttles with lots of power that cause substantial aircraft pitch excursions, or on occasion lag in necessary power application which requires immediate hand-flown thinking and intervention—despite flying in automated state—we see a myriad of potential “gotchas” developing. This is worth thinking about as new pilots, some with professional flying in mind, learn to fly; their training may integrate automation from the beginning, until they are on their own, supposedly competent and confident to fly both automated and manually . On the other hand, pilots who have the ability and confidence to hand-fly, especially with basic flight instrument information, usually disconnect the autopilot, stay on course, and get everything organized. Then, if not continuing an

approach to landing, they wait until things settle down and attempt to reintroduce the automation simply and methodically. There are times when we can solve an automation problem through a quick selection of a new mode for the autopilot’s operation, and subsequent easy selection of new target information; airspeed, altitude, heading, etc. It is, however, a fine line that varies with things like how high we are, phase of flight, and so on. An important part of this relates to how well one understands the autoflight and electronic flight system. By the nature of their computerized design, it’s pretty difficult to learn every little aspect of these systems or remember it if we did. It’s important to realize that fixing a problem while flying on automation has the same goal as when we fly manually: keep the airplane flying normally, staying on course and altitude. A simple example of fixing a problem while staying on automation could be the aircraft failing to follow a programmed course or vertical flight path. It might be easily fixed by selecting the “heading” mode or a nonprogrammed verticalpath mode of the autopilot. We can then use that mode to stay on course from primary navigation information or control the climb and descent ourselves. Then, when we have time, patiently try to figure out what’s wrong with the programmed information. If that route excursion is near the ground or in hilly terrain, we don’t have time to fiddle with buttons and knobs or contemplate what’s wrong. Instead, we take over manually and seamlessly continue the required flight path, using primary instrument indications. Other critical examples might be autopilot issues, such as capturing erroneous altitudes due to some strange programming issue or flying through a preselected altitude. To be aware of these things, it means we have to know what the airplane is supposed to be doing, and what it is doing. That’s being “in the loop.” Again, when single-pilot, without that second set of eyes, we have to discipline ourselves and pay attention, especially when our autopilot is following programmed lateral and vertical flight paths, and pay careful attention when the aircraft is supposed to level at an altitude. When automation fails during an instrument approach, unless we’ve caught the issue early on and are within parameters, it’s pretty much like a manually flown approach that gets out of bounds; it’s often better to make a missed approach. After we’ve completed the miss, we again methodically set up the approach, and then fly it only when we are ready. With the nature of an approach being an operation close to the ground, it’s not the time to be racking an aircraft up, down, back, and forth, trying the save an approach that we can easily try again.

Programming Thoughts Compared to aircraft with simpler avionics, preflighting and programming a

technically advanced airplane takes a lot more time. When these systems first emerged, if we were rushed before departure, the idea was to program enough information to get airborne and a fair piece down the road. The rest was to be done in-flight. Whether airline or general aviation, this idea more likely increased workload, especially if something happened after takeoff that kept us distracted. If we can, programming our complete route before beginning the flight is a good idea, especially with an FMS-type system that calculates fuel and time planning. Unfortunately, some systems, whether from design or capacity, can’t always program complete flights; if so, we need to do our clerical work in unhurried times, and especially try to avoid such distracting work during climbs and descents. During flight in a true two-pilot, EFIS, FMS, and advanced autoflight operation, the airplane is flown on autopilot while one pilot programs and the other monitors the flying. Then, with roles reversed, the other pilot independently reviews the whole flight plan loading operation, verifying the route. Obviously, this isn’t much help for a single pilot, with an autopilot not making things equal. This highlights, again, our need to be on the ball when programming in-flight. Do we need maps? You bet, and as said before, even if not right in front of us, we want them close by and easy to fetch. A big issue when flying single-pilot in a busy cockpit is traffic avoidance; unfortunately, it usually takes a backseat to everything else. Having collision avoidance equipment is a very good idea, but it is not the total answer, especially around busy VFR airports; not all airplanes have transponders, or they may not have them on. Eyeballs are current and important technology. Programming electronic flight systems, whether in a single- or two-pilot operation, demands exact information that is entered totally correct. All numbers, letters, and spellings must be input with zero error. For example, “GLYDE” intersection just west of Worchester, Massachusetts, is about 1,210 nautical miles east-northeast of “GLIDE” intersection, which is just west-northwest of Salina, Kansas. In a hectic moment or on the tired side of a day … well, the idea is obvious! There are plenty more examples. That’s why we hear experienced pilots asking clearance delivery or ATC how to spell certain navigation fixes. If we don’t catch these mistakes, especially as the airplane turns off-course for Kansas, it could be a real problem from ATC and/or terrain avoidance issues. How can we check a routing to see if it goes where it should? Depending on our system, we might check total programmed mileage, time, or course directions versus our flight plan. In other words, if a flight-planned 200-mile flight shows total mileage of 1,200 and six hours flying time, or one segment of the flight goes in the opposite direction, we’d better look into it; but it’s not always so obvious. If we can “page through” the route and watch it on our EHSI or MFD, we’ll see whether the course heads off into the boonies or disconnects between navigation points. That’s called a “route discontinuity.” If not caught, and we’re asleep at the

wheel (hopefully not literally), the airplane will usually take up the last route’s heading, flying along until we run out of fuel—or we wake up to the problem. Again, think traffic and terrain. Now add programming of vertical navigation to include crossing restriction altitudes. There was one situation where a crew, in vague state for whatever reason, saw a planned altitude change in their screen and made the climb without contacting ATC. Brain up and locked; nobody got hurt, but it didn’t go over so well! If we use things like Bluetooth-transmitted flight planning, we should still check our final EFIS routing. As a side note, think about this routine when a bunch of passengers are babbling or asking questions or an entertainment system is singing away in our headsets. And do we really need our cellphone in the loop? This seems a time for restraint, kind requests for quiet, or offering simple crew tasks to keep passengers busy. Obviously, when we fly a single-pilot, technically advanced operation; we have our work cut out for us. We need to be well trained and current, with the personal discipline not to get lazy, even when tired or hungry. We need to develop personal systems that give us the best next thing to being in a two-pilot crew, not just for redundancy but for knowing when things are not up to par and we need to back-off accordingly. We have to be on the ball, and many do it well.

Summary of Flying Basics in a Technically Advanced World These are suggested thoughts that have served well for us and many others. • Learn good basic hand-flying skills. • Learn good basic hand-flown instrument flying skills, with only primary instrumentation—mechanical or electronic. • Then introduce equipment such as programmed navigation, electronic instrumentation cues, and automation, with an understanding of their operation and management before attempting to use them in-flight. • Be capable and current with whatever level of equipment and conditions one plans to fly. • Practice hand-flying with regularity, as allowed by one’s ability and the conditions, especially during climbs, descents and approaches. • Before any flight, be well prepared and fully organized, with as much electronic programming completed as possible, before the flight begins. • If at any time during a flight we are pressing our limits, or feel uncomfortable, turn around or divert to a safe destination. • Have the ability to comfortably and safely hand-fly the flight with the lowest common denominator of instrumentation. • Throughout any flight, at the least bit of confusion or distraction, always check the primary flight instrument indications, whether we’re flying with automation

or by hand. • Always fly the airplane first .

1 . Federal Aviation Administration. Advanced Avionics Handbook, FAA-H-80836 . Washington, D.C.: United States Government Printing Office, 2009, chap. 1, p. 3. 2 . FMS/RNAV: Flight Management System/Area Navigation, which requires programming and attention away from basic flying of the aircraft.

15 Thunderstorms and Flying Them Thunderstorms are thunderstorms, and while they may come from different beginnings, they all turn into the same thing. Once a pilot is in one, he or she wants to know how to fly through it and come out safely. Even more important, however, is keeping out of it in the first place; and no matter how old or bold a pilot may be, the primary thoughts about thunderstorms are concerned with staying out of them. To stay out of thunderstorms, or fly through if we must, we should know what thunderstorms really are and the different backgrounds from which they come.

What Are They? Simply a cumulonimbus (Cb), thunderstorm, TRW, or T, or whatever one wants to call it, is a concentrated mass of very unstable air in violent motion up, down, and sideways. It has strong, gusty winds that generally extend to the ground and make landing or takeoff difficult or impossible. It has thick clouds, heavy rain, and sometimes hail. Electrical discharges occur frequently. Some thunderstorms have tornadoes associated with them, but most don’t. Tornadoes, however, never occur without thunderstorms. Tornadoes are associated with thunderstorms, but they do not always come out of the big, bunched-up cumulonimbus clouds with the highest tops. They often come from much smaller clouds that hang back in a line from the main storm center. So it’s wise not to duck under or fly through clouds close to a thunderstorm just because the clouds look smaller and have lower tops. To make a thunderstorm, we need conditionally unstable air. What’s that and who cares? Well, it’s air that is stable as long as it doesn’t condense … that’s the condition. When it does condense, the release of heat in the condensation process makes the air warmer, and the air wants to go upward. Then more moisture condenses, more heat is released, and it goes up more. It’s almost like perpetual motion, and the energy released is tremendous. The normal places we go for weather information do not tell us the analytics that determine whether an air mass is conditionally stable or unstable. That is learned from upper air soundings, such as the previously mentioned Skew-T log-P information, taken in many places over the country and other factors, then analyzed by computers at the National Weather Service and Storm Prediction Center, as well as other sources. The result is the forecasts we use, and if they call for thunderstorms, it means the air is conditionally unstable or will be, and that’s

all we need to know.

What Is Tough about a Thunderstorm? What really bothers us most in a thunderstorm is the turbulence. Lightning discharges are a minor danger, and few airplanes have been knocked down from lightning. There has been concern of flame going up fuel tank vents and then igniting a near-empty tank loaded with explosive vapors. Redesign of vent systems, plus a method of discharging inert gases into the offending vent system when any ignition occurs, is intended to alleviate the problem. As for lightning hitting a plane and knocking it down, there is evidence years back of the previously mentioned and corrected fuel vent issues, but overall, metal aircraft as well as composite aircraft properly protected do not have catastrophic issues. This protection to composite aircraft is usually provided by thin metallic conductive strips or webbings molded into the aircraft skin, which also may connect metal parts. The protective conductive layer is typical on today’s allweather composite aircraft, which includes the popular single-engine aircraft of this category, but not all lighter sport aircraft and sailplanes. The process, at times referred to as bonding, also has used internal wiring between metal parts of composite aircraft, this being typical of the earliest composite aircraft from decades ago—those made of wood. Lightning strikes to composite aircraft seem quite rare, and does not necessarily mean the end. However, in one documented case, a fiberglass sailplane was struck by lightning, in visual conditions under cloud, and was basically blown apart. The strike hit the left wing at the aileron pushrod and exited out the right wingtip area; the transiting “overpressure” from the electric charge did the rest, destroying wings, controls, and fuselage. Fortunately, the pilots wore parachutes and exited accordingly, both being okay. Of thought is that a ballistic parachute would not have helped, as there was no remaining cohesive structure to support. Again, a very rare event, but interesting. I (RNB) spent a number of years looking for and flying through thunderstorms in research work and saw a lot of lightning. Numerous electrical discharges were experienced, where the aircraft was at one end of the lightning cycle—four in one day—and the worst damage was a hole about the size of a half-dollar burnt on the trailing edge of control surfaces. Bigger holes have occurred, but they generally aren’t caused by lightning. When I had a discharge in a Boeing 707 out of London, England, a 3-foot-long piece of the black radar nose was torn out. The lightning actually made a much smaller hole, but the high-speed air from our forward motion got inside the nose and then tore out the bigger piece. There wasn’t any special problem, but I dumped fuel and returned to have it fixed before crossing the Atlantic.

Damage to a Boeing 707 from an electrical discharge, often called a lightning strike. The point of discharge is small and near the point where fuselage and radome meet. Large, torn pieces were probably ripped out by airstream wind. None of this affected the airplane’s flying ability.

Tornadoes Flying into a tornado, of course, would be catastrophic for an airplane. The winds are unbelievably violent. But tornadoes can generally be seen if one is outside cloud, flying VFR. The big hazard is sneaking under thunderstorms at night or down low in and out of cloud. There is always the chance that while you are sneaking under clouds near a thunderstorm, a tornado may form, perhaps where you don’t see it. I (RNB) was lucky one night, in a DC-3, flying from Chicago to Indianapolis while trying to squirm my way through a line of thunderstorms. Flying low, as we often did in preradar days, the idea being to stay “contact.” Ahead I saw a strong glow that turned out to be a large field on fire, probably started by lightning. But the shock was to see this fire lighting the sky enough to show a tornado with its scary funnel right on course! I went around it, somewhat shaken, because what if that handy fire hadn’t lit up the sky! It’s always useful to have a little luck around. It is potentially possible that we could pass above a tornado, at an altitude above the base of the thunderstorms, perhaps 8,000 feet or more. It will be a ride to remember, but the violently destructive part of the tornado may be missed. However, by far, the best decision is to avoid the entire area. In those many years ago of low flying without radar, a friend passed over the

Pittsburgh, Pennsylvania radio-range station in a DC-3 at 8,000 feet while a tornado was going by on the ground at almost exactly the same place and time. He didn’t have a bad ride and flew on to Washington, D.C. There have been numerous cases of this sort, so there’s more than just theoretical evidence that the violence of a tornado is only in the low levels, but still, this is not reason to make an assumption and fly in these situations. In those days, there were also a lot of airplanes lost; why repeat history? Part of the reason for my friend’s good ride was that he probably missed flying through a cell. Tornados can potentially come out of both high and low cloud base convective weather. One wild West Texas summer day in 1967, during a national soaring competition, a spiny little tornado touched down out of a confused area of thunderstorms, their bases about 12,000 feet. It was not raining, and just a few miles to the north the sky was clear. I (ROB) was circling in lift well below base, when one glider called the tornado. Miraculously, there was only one incident concerning the ten or more gliders in the same area. That pilot suddenly found himself in extreme turbulence, was flipped inverted, then fell in totally dead air with no control action. As he worked on a way to bailout while upside down, the controls “bit,” and he was able to roll out and fly back to the airport. Fortunately, he was flying a strong metal sailplane, which no doubt helped. What’s interesting about that day is, with about ten gliders in a few mile radius of that one pilot’s dramatic event, we had a kind of data-plot, with the gliders sampling the air under the storm. It shows how localized, unpredictable, and hazardous thunderstorms can be. In retrospect, that one pilot may have been in a dry microburst, which we’ll chat more about later in the chapter. One criterion, developed by Dan Sowa of Northwest Orient Airlines, is that if the reported radar top of the thunderstorm pushes up above the tropopause by 10,000 feet, the storm has tornado potential. One can get thunderstorm top reports from computerized data, the FSS, Flight Watch and NEXRAD. If we have found our source for tropopause data, we can keep an eye on things, but even without tropopause data, seemingly excessive tops should have us heeding things carefully. We should not put precise accuracy into top reports, but knowing the tropopause height gives us a better indication of how high the thunderstorm tops will be—the height of the tropopause plus a few thousand where the storm’s energy pushes severe thunderstorms into the stratosphere. Not all thunderstorm tops are greater than the height of the tropopause; it’s the only inversion to shut them off. However, when they do exceed the trop, those storms should get serious respect!

Hail Hail is always a problem, but compared with the number of airplanes flying in and around thunderstorms, not many are hit by hail. As for aircraft actually being

knocked down by hail, some have been pretty well beaten up, but still flew to safe landing. There is a problem with hail damaging a jet engine, so it loses its effective power, with some previous incidents resulting in catastrophic forced landings. Operationally, it’s important to know our aircraft’s procedures for dealing with hail. Jet engines seem more affected, and usually procedures recommend turning on the jet engine’s ignition source, then make little if any power changes. Of any power changes made, we make them slowly. Most hail comes out of the big overhang cloud that is downwind of a thunderstorm; if it’s visible, this is the place to stay away from, even if it looks clear and pleasant there. You might get right under it when the hail dumps, and again, does so unpredictably. Thunderstorms demand a wide, respectful berth! Heavy rain can cause engine problems in the form of carburetor icing, and all precautions must be taken. Sometimes the rain seems so heavy in a thunderstorm that the engine should simply drown. There is still some question about jet engines in heavy rain, so it is important to follow recommended procedures meticulously, which pretty much emulate the hail procedure above.

What hail can do to an airplane. But it flew! (NOAA PHOTO) On a side note, hail does not do favors to aircraft, whether flying or not. It can be especially damaging to composite structures, which are different from metal, especially in repair. If an aircraft has had a hail encounter, either in the air or on the ground, we should have someone qualified to inspect and repair these structures, and take a good look at the aircraft, not only for deformation that affects aerodynamics, but the structure as related to the load-bearing composite

surfaces; composite damage can be less obvious than metal. On composites, even very subtle dents can mean more than they seem. This came about in the 1960s, when beautiful fiberglass sailplanes were new concepts, and suffered hail damage around thunderstorms.

The Bad Part The big problem with thunderstorms, as we’ve said, is turbulence of sufficient severity to make airplane control difficult. The turbulence may be severe enough to tear an airplane apart, but most likely that structural failure follows loss of control and subsequent high airspeeds that may reduce the airplane’s structural integrity. Also, flying ham-handedly will not help matters. Airplanes are pretty tough and, if flown properly, will probably traverse a thunderstorm safely. This isn’t meant, in any way, to suggest that pilots fly through thunderstorms on purpose. It is, and always will be, best to stay out of them. There is some evidence that if certain severe thunderstorms are encountered at the point of their most potent growth, it may not be possible to maintain control or keep the airplane in one piece. Landing with thunderstorms near or on the airport is a hazardous operation. Most landing shear accidents have occurred with thunderstorms nearby, but some not so close to the airport as well. Near the ground, as on final approach, is the most difficult area to handle thunderstorms. There’s no altitude buffer in which to recover, as we’d have up high, where altitude can safely be lost during a rough ride. Close to the ground, an uncontrolled altitude loss is disaster. In the past we’ve always known, through observation and experience, that winds close to a thunderstorm are squirrely, gusty, unpredictable in direction, pushy, jerky, violent, and sometimes cover a bigger area than imagined. We learned it wasn’t smart to get too close, especially in landing, and definitely not to takeoff into such situations. Today, research has analyzed and put names on all this: microburst, macroburst, gust front, downburst, and so on, but this hasn’t changed the action; it’s all out there, just as vicious as ever. There has been progress in predicting these conditions, both from ground-based systems as well as on-board aircraft, but mostly at larger airports through ATC communication or more advanced, larger aircraft, especially airliners. When we fly our nice general aviation aircraft into smaller airports, we’re back to the way it was, finding it difficult in locating these conditions precisely, quickly, and then getting the information to the pilot. Quickly means a matter of seconds in some cases, so that no matter what system may come in the future, Doppler radar-based for instance, it’s of no use unless it gets to the cockpit, and fast! Ideally, the sensing and warning system which finds wind shear should be located on the airplane, displayed and announced right in the cockpit, such as we find in predictive wind shear systems on larger aircraft.

This is far more sensible than information from ground-based warning systems, their warning delayed through intermediary communications from the control tower at the airport. Of the onboard aircraft systems that provide wind shear escape data, and are found mostly on larger aircraft, they should not be a panacea for landing in or near thunderstorms. There are some storms and conditions the airplane, instruments or not, cannot handle! The classic wind shear profile is first a headwind, which boosts airspeed and tends to make the pilot reduce power, followed by a sudden loss of airspeed, which then requires scrambling to get lots of power back on, plus an increase in angle of attack—pulling back on the wheel or stick—to combat the severe sinking. The trick is to pull back to get maximum lift, but not so far as to stall the airplane. The power of jets makes their “escape” maneuvers dramatic and usually successful if properly flown. The procedure applies full power—thrust levers to the stops—as we rotate the aircraft nose up, usually tickling the stall warning; whether a stick-shaker or otherwise. The target for pitch attitude, on jet transports, is usually about 15° nose-up. With power-to-weight ratio around 3 to 1, we will not get this performance from most light aircraft. The cockpit wind shear avoidance instrument systems help the pilot fly through the shear with precision, but without this instrumentation, the pilot is just searching for something in the dark. Another aspect of the instrumentation is that it defines the event through its sensing of many parameters, then blares an aural warning, saying, “Wind shear … Wind shear,” to which we react. Without such a warning, we have to be the parameter computer, and sometimes these events are not cut and dry, nor easy to define. Either way, we don’t want to get the idea these instruments find and announce the condition far in advance. When they sound off, you’re already there! There’s another important aspect of nasty winds, and that’s the vortex part of a strong downburst, microburst, macroburst, or whatever you want to call it, which often is encountered after the classic shear. This vortex area is where the wind currents are turning and tumbling without any organized pattern or sequence and can best be described, again, as squirrely. This in turn means the airplane can be battered up, down, and sideways in a matter of seconds in no comprehensible order, and there aren’t any instruments for that! The pilot just pushes, pulls, and twists, trying to handle what’s happening so fast it’s almost impossible to analyze and fly it. Although fortunate to have only flown such a drastic event in a simulator, nevertheless, it is a time when we truly feel we’re on the edge of losing the airplane, requiring efficient and quick response to the attitude indicator; we realize we’re on the brink of hitting the ground, yet have little, if any, time to glance at an altimeter or outside. If you ever get the chance to fly these events in a simulator, it will give any sane person a reason not to get into the predicament in the first place. Just before finishing this book revision, I (ROB) had the opportunity to

observe a wind shear event in a simulator, but it was flown on a Boeing 777’s extremely capable autopilot, which in the real world is not normal procedure. It was a rare chance to relax and watch these otherwise frantic, hand-flown events. The footprint for the microburst followed that of an actual microburst /wind shear accident, years ago and with an older aircraft design. During our simulator event, the aircraft settled to eight feet above the ground, as read off the radio altimeter, then recovered. Most interesting was display of angle of attack—finally displayed on an airliner—that thrashed between -2° to +21° degrees, at a rapid pace that could not be followed if one used the angle of attack for hand-flown guidance. However, what allowed the escape, was the computed data of the aircraft’s wind shear-guidance system, which the autopilot followed precisely, as seen through the flight director pitch-bar and what we would fly in a real event. The success of the event was the warning system and the very powerful airplane; anything less would not have made it, and even this simulated, very powerful airplane came close to not doing so. When approaching to land, it also isn’t likely that Mother Nature has politely set the microburst, shear, or what have you exactly centered on course. So we may hit the side, corner, or who knows what part of the violent winds. This will, of course, confuse the action pilots think they are taking. What all this says is that in some cases we are at the mercy of the tempest. Obviously it is best to avoid it, and we repeat: do not land or takeoff with a thunderstorm on or near the airport. This brings up the negative side of technology. In this case there’s a mistaken idea, conscious or subconscious, that modern radar can show thunderstorm boundaries well enough so that we can fly close to them and ATC can also vector us close by the storm. Not true! Distance required from a thunderstorm hasn’t changed, and detection has not improved enough to show the sharp demarcation between smooth and turbulent air. In addition, both pilots and controllers generally have not grasped the fact that a thunderstorm can develop, become vicious, and do nasty things in minutes. Consequently, shaving the edge too close is not only basically hazardous, but there is additional danger in that the air can change from smooth to impossibly rough in moments! Even if the airport we are dealing with has a Low-Level Wind Shear Alert System (LLWAS ) and Terminal Doppler Weather Radar (TDWR ), we should not drive blindly into compromised, convective weather. There have been times when an LLWAS didn’t work, because wind sensors are located away from the localized, 1 mile or so diameter microburst, missing the event. There is also big improvement with the Doppler radar systems, but we still need to be careful. Also be skeptical of ATIS weather information; it can be very old, sometimes up to nearly an hour, compared with the urgency of rapidly changing thunderstorm activity. ASOS/AWOS is quicker, but again cannot see approaching weather, although some of the systems detect thunderstorms at the automated observation

site. It is up to the pilot to be cautious and vigilant, using any means to get the news, regardless of outside help. How? Of course, know the general weather situation, use our own aircraft’s airborne weather radar, if we’re fortunate enough to have it, or data link displayed NEXRAD with time-lag caution (more on this time-lag later in the chapter). Most of all, we should use our eyes to watch carefully for fast developments and consider proactive deviation to wait things out before a shear event can happen. Fast development means big cumulus (cu or Cb) becoming thunderstorms within minutes. If an airport weather report says “towering cu and Cb,” be careful to check that they aren’t turning into thunderstorms—especially in the afternoon or with approaching fronts. This can happen so fast that the airplane landing ahead of you may fly through an innocuous rain shower on approach, but when you come in, minutes later, the storm may have developed fully and dumped its heavy rain and the downbursts, micros, and so forth with it. This has tragically occurred, just as we tell it here. If there are towering cu and Cb with rain showers in the area, be extra suspicious and alert for sudden thunderstorm development. Again, as a reminder, ASOS/AWOS fails here, in that the automatic airport weather reports do not tell you of towering cu or building Cb. They have to be supplemented with human observation of the weather for that information, or we need to use our own eyes. If we fly an approach—or departure—near thunderstorms and encounter wind shear or other indicative issues, we should broadcast a PIREP to the tower or appropriate ATC facility. A timely PIREP can literally be a life saver, even to an aircraft minutes behind us! These wind shear and microburst situations are, again, ones in which the pilot had better remember that ground-based weather data isn’t going to be fully dependable for getting the information into the cockpit fast enough; it’s up to the pilot to be on top of it. Incidentally, the first mention of downbursts, as a result of thunderstorm rain, was by C. E. Buell in the July 1945 issue of the Journal of Aeronautical Meteorology .

Their Life Cycle Thunderstorms, like everything else, are born, live, and die. They do it faster than one might think, but as one dies, another forms. You do not see all this when approaching an area of thunderstorms. Large clouds pile up in great masses, and unless there’s just one lone thunderhead of an air mass or orographic type, there will be high, intermediate, and low clouds, as well as the cumulus. All these clouds aren’t wild and rough; most of them are not and contain only light to moderate turbulence. But buried in those clouds are thunderstorm cells, their width anywhere from a few thousand feet to miles across. In these cells, things

are rough and wild. They are the heart of a thunderstorm. The storm may have started as a snappy, jolty little cumulus that formed and started to grow. It continued to grow and finally became so high that it passed the freezing level; there it stopped being a simple cumulus and became a thunderstorm. This is the cumulus stage, and during it, the cloud is almost all updrafts, some going up 3,000 feet a minute and sometimes more; there isn’t any anvil or rain. When I (RNB) was doing weather research, we measured electrical fields and flew a lot of cu and thunderstorms doing it. One early afternoon, over the Pocono Mountains of Pennsylvania, I flew into a large, growing cu that was going through about 14,000 feet but didn’t show any signs of being a thunderstorm. It turned out to be one of the roughest rides we ever experienced, and the electrical field strengths were tremendous, which says it doesn’t have to be a full-blown thunderstorm to be dangerous. The building and early stages are the roughest. This is not necessarily a rare occurrence. Airplanes have flown through similar low-topped, but growing cu only to find their ride pretty spicy. One event, in a wide-body jetliner, had the aircraft pass through an innocent looking cumulus with tops not much higher than 11,000 feet, but things were thrown around the cabin and a few folks were injured. The main point here is that if a cumulus is growing with real clout, it will be rough, most likely well before any precipitation has developed, which means there is nothing to paint on radar. The way to study a growing cumulus is by careful scrutiny of the very top part of the cloud, the shreds and pieces. If one can see a spilling, growing action, and if it’s “busy,” there’s lots of action inside, and it’s growing. Any indication of a small, flat, thin cloud around the edges, near the top, is strong indication that this cumulus is becoming a thunderstorm. The mature stage follows the cumulus. It begins when rain commences. The cloud develops downdrafts as well as updrafts, along with heavy rain. It’s still very rough because of the added conflict of air moving up and down. After the big anvil has formed off the top, the thunderstorm enters the dying stage, the wild currents decrease, and it calms down, although it still looks pretty bad. That’s the way thunderstorms come and go, but from a cockpit, we want to know more practical things: Where are the tops, the bases, how far through, what’s in there, and very important, what kicked them off in the first place? Because if we know that, we have a start in knowing how to combat the particular storm we’re facing. There are three basic ways thunderstorms are created: 1. By heating. 2. By a front. 3. By orographic influences, such as air moving up a mountainside or sloping

terrain. All of these can unite and produce thunderstorms faster and more violently than usual. When a thunderstorm occurs because of air-mass moisture and instability, the air mass will be heated faster and rise to its condensation level quicker on the sunny side of a hill, where glider pilots would look for thermals; a flow of wind up the mountain will also add impetus to the process.

Three stages of a thunderstorm (from left to right): 1. The early or building stage. Lots of updrafts and rough. 2. The mature stage. Heavy rain, possibly hail; up and downdrafts; chopped-up, rough air; and strong surface gusts ahead of the storm. 3. The drying (dying) stage. Mostly downdrafts. Rain diminishing and not very rough. But it still looks that way. (NOAA IMAGE) A front shoving air aloft on its own will do it faster and with more “oomph” if that front is climbing up sloping terrain, and even more so if it’s doing all this during the hot part of the day. So hills and mountains make thunderstorms tougher, as they do other weather, and the rule of extra care in mountains applies again.

A Clue When the weather services report actual thunderstorms, they give the direction from which the storm is moving and its velocity. This velocity should not be confused with the general speed of the weather system, such as a cold front. The speed is strictly of the individual storm. There is a definite correlation between this rate and the storm’s severity. If it’s over 20 knots, the storm will be strong, and if over 30 knots, it will be severe. In one of our worst airline thunderstorm accidents, the cells were traveling more than 60 knots. If a rain shower—not a

thunderstorm—is moving over 50 knots, it will have strong turbulence and deserves caution.

The Different Kinds Now what do the different thunderstorms mean to us? Air-mass thunderstorms are generally scattered, and theoretically we see them and wander around, getting where we are going without flying through any storm.

Isolated thunderstorm. Note overhang extending from the storm. Under the overhang is not the place to fly! Hail often falls from there, even in the clear air, if upper winds are strong which blows the hail downwind of the overhang. Also, close in under an overhang can be quite turbulent. If deviation is started far from the storm, the miles added to the flight can be insignificant. (PHOTO BY ROBERT O. BUCK)

Bright spots ahead, but very risky flying through those openings. Both overhang turbulence and hail potential, as well as lower cu growing and closing up the hole, potentially trapping us into flying through a thunderstorm. Go around the area! (PHOTO BY ROBERT O. BUCK) We see this in the Far West, where thunderstorms occur in classic form. The visibility in the semiarid areas is excellent, and if anything less than 50 miles is reported, one looks at it with suspicion. Here, it is easy to waltz gracefully around the big Cb, watching its dark, foreboding rain and flicks of lightning from a safe and interesting position. However, away from these regions of unlimited visibility, air-mass thunderstorms become more of a problem as we fly in midwestern and eastern summer haze. If we are working our way through air-mass thunderstorms in reduced visibility, the place to be is on top of the haze level, where we can see the thunderheads. It’s worth repeating that when doing this it is important to make certain that broken to overcast clouds do not creep in under us and that we keep track of the general weather situation. Air-mass thunderstorms do occasionally line up in a sort of fake front if the condition favoring the thunderstorms is strong. This generally occurs in the late afternoon.

How High? Thunderstorm tops are high—35,000 to 80,000 feet—depending on the part of the world. Except in rare situations, any Cb worthy of the name doesn’t stop at 25,000 feet. Almost any fully developed thunderstorm will keep right on climbing until it pokes up into the stratosphere. The tops are generally lower in far northern and far southern latitudes, and so

is the stratosphere. We’ve flown over the top of thunderstorms at 33,000 feet above the North Atlantic, but in southern Italy, I flew next to thunderstorms at 35,000 feet that looked as far above me as I was above the ground. Thunderstorm tops don’t extend much into the stratosphere, because the stratosphere is an inversion: the air is warmer than the rising storm’s air, and so it’s stable and shuts off a thunderstorm, even though momentum may drive it up into the stratosphere for a few thousand feet or so. In the United States, the tops are rarely below 35,000 feet. It’s obvious that small aircraft don’t try to top thunderstorms and big airplanes don’t do so too often. There are problems for both kinds. If a pilot does try to top a thunderstorm, or a line of them, that pilot should be prepared for turbulence, even in the clear; rough air often extends above the storm’s top. On occasion, we’ve passed over rapidly growing, towering cu—ones you can just see boiling away as it lunges skyward—but they’re still a few thousand feet below. They gave us a good solid wallop, as we passed over quickly in a fast jet, from the rising air currents exceeded cloud development. I’ve heard slower aircraft doing high-altitude research have felt this lift as a wave-like surge. In any event, it’s worth avoiding those tops, just as you would any Cb.

A thunderstorm taken at 33,000 feet. There are several things to note: an overshooting top on the right of storm, possibly sneaking through the tropopause, meaning a strong storm; and the wispy cloud-like part is possibly hail. In the lower right, a rain shaft is coming out the storm’s bottom, along with a lower shelf cloud left of the rain. This storm was moving northeast (right to left) over 30 knots, ahead of a strong cold front. It is not only important to avoid these storms by considerable distance, it would be foolish to try and top any such weather in the area. (PHOTO BY CHRISTIAN O. BUCK)

Years back, with sporadic areas of uncontrolled airspace in the United States, it was not uncommon for folks to soar sailplanes right into the cumulus clouds. In the early 1960s, an acquaintance did just that in West Texas, entering the cumulus at around 12,000 feet, with cloud tops estimated in the high teens. The sailplane was equipped with gyro instruments, oxygen, and the pilot had an excellent instrument flying background. The climb rate smoothly increased to dramatic level, later measured off his barograph, in one point of the climb, as 8,000 feet per minute! He passed through rain, snow, and ice, finally popping out the top near 30,000 feet, out climbing the cloud’s growth. Heading out into the clear, he wove a dramatic and scenic descent between beautiful cumulus, landing with the last water drops from melted ice dripping off his wings. This cloud climb was just at the right time, with not much turbulence, but many such climbs have become harrowing rides—for those who desire doing such things. Also, sailplanes are built to stronger limits than most general aviation aircraft, and the folks who did these things were excellent, old-school instrument pilots. However, returning to our world of powered aircraft, if an airplane is staggering along at a high angle of attack, struggling to get on top or stay there, it may be close to its thrust limit. If an upset or stall occurs from, say, clipping a Cb top when trying to top one, there’s not enough power to help recovery, and thousands of feet may be lost in the attempt to get the airplane flying again; if successful at all. An upset with a jet is a particularly tricky thing from which to make a recovery. The airplane generally pitches up first, and the natural reaction is to trim forward; then a dive follows, and big control forces are needed to overcome the nose-down trim and dive. It’s probably impossible! Very possibly, the heavy pulling back, plus the speed, will load the stabilizer and “stall” the trim motor from actuation, and without returning to nose-up trim, there is not enough elevator authority to allow recovery. There’s nothing to do, except unload it by letting up on the hard pull and then try to trim. This is one of those theoretical but highly counterintuitive and maybe impractical tricks. The upset is a complicated area having to do with speed of sound, shock waves, and air density. The recovery is often a matter of diving wildly toward the earth, sitting there pretty much helpless until the speed of sound changes with the temperature increase and the air becomes more dense, because of lower altitude and higher pressure; then the airplane gets enough control force for the pilot to recover. A number of these didoes have occurred, and it’s a testimony to the structural strength of jets that mostly held together, albeit some were stretched and strained.

A very unique shot of an overshooting top of a thunderstorm, well into the tropopause. The “flowering” top is probably cloud and hail from extreme updrafts. We were farther from the storm than it looks—it was serious business— so with our height about 35,000 feet, this storm was thousands of feet higher. Because most general aviation flying will be lower and not in view of such a tops image, it’s more reason to heed and avoid high tops, especially if they’re reported through the tropopause. (PHOTO BY ROBERT O. BUCK) Either way, it’s difficult to overstate the danger of trying to top storms, and even going over them with apparently good speed and control is a more risky flying condition than one may realize.

The Cloud Layers If we are flying around storms, trying to stay on top of lower clouds, we can get into a bad situation. Let us say we are on top of the haze level. We see numerous cumulus poking up through; they look like bunchy, thick cauliflowers. They are easy to wander around, but finally they seem to be connected by lower clouds, and the tops of these lower clouds approach our cruising level. This can happen, depending on the stage of development, anywhere from 8,000 feet to more than 30,000 feet. Almost without realizing it, we’ve been climbing to stay on top, and our airplane is grunting to do the job. We are being suckered in, as the blunt expression goes. Big cu tower to either side of our course. Ahead is a lower spot with bunchedup cu. We head for the lower place and hope we’ll get over and beyond before it builds up to our level.

They Grow Fast Something we should realize, however, is that those cumulus can build very fast and turn into thunderstorms. I (RNB) watched one build in Texas. At 11:30 a.m., it

was a pleasant-looking cumulus, and at 11:45 a.m., it was a big, solid, bunchedup-looking cu, and at 12:00 p.m., it towered to tremendous heights, its bottom was black, rain poured down, and lightning crashed to the ground! (If you remember the story about the tornado at the glider contest, it was the same day.) When one stops to consider that thunderstorms in the cumulus stage can have updrafts of as much as 8,000 feet per minute, with 2,000 to 3,000 feet per minute fairly routine, it’s obvious that a growing thunderstorm can out climb an airplane of average performance. So as we sneak through that “low” spot, we should realize that there’s an excellent chance that the “low” spot will come up to us, around us, and envelop us. One cannot try to top growing cumulus unless willing, able, and prepared to fly through a thunderstorm, because that’s what it may finally come to! A VFR pilot flying on top of the haze level to spot Cb development hasn’t any business flying on top of clouds that are bunched-together masses, poking up to higher altitudes in places, with the ground only occasionally visible. When the cumulus surrounds us, and the only path ahead is over some other cumulus, or through low spots between them, then it’s time to turn around or land. The instrument pilot who feels it’s okay to flirt with growing tops and try to slide over the “saddles” between them had best remember that no matter how experienced one is, a stalled airplane in a thunderstorm is in a desperate situation, and the cleaner the airplane, the more desperate. This isn’t just a jet aircraft issue, as higher performance, turbocharged single-engine piston aircraft flirt with high altitude flight. As we said, if this kind of flying is going to be done, then one must be willing and able to fly in a thunderstorm. What’s willing and able? First, one must be a competent instrument pilot who can fly the airplane well in heavy turbulence. Then, one must have enough instruments, good engine-heat capability, and at least airborne radar. That pilot must be able to hand-fly while flying in instrument conditions, as an autopilot cannot always handle very turbulent conditions. Lastly, this is not the place for a ballistic parachute—parachutes do not do well in thunderstorms and, as we keep saying, a parachute should not be a crutch for compromised flying ability or judgment.

Cumulus building. Although we’re looking from over 30,000 feet, if we were down in the area of, say, 15,000 feet or lower, we’d be facing canyons of growing cu. These clouds will probably produce thunderstorms, but for now, as they grow, they probably don’t show on radar, because they’re not wet enough: no rain. So we would not know they end to the right or see other open areas. For VFR pilots, it’s a situation requiring calm work to get down and out of it. For IFR, it may mean an instrument clearance or climbing on top if the airplane can get high enough— 15,000 feet plus—and then wiggling between these towering cumulus. (PHOTO BY ROBERT O. BUCK)

What’s Inside All Those Clouds? Let’s go back to our line of towering cu with the lower spot between. As time goes on, the lower spots will be higher, and finally a solid line of massive cu and Cb cuts across our course; they may be lined-up, air-mass thunderstorms in the afternoon, or a genuine front. Either way, it looks impressive and has the appearance of one big line of thunderstorms. If we could really see inside that line, we’d find a row of heavy clouds with numerous thunderstorm cells inside. If we barged through and missed the cells, we’d get light-to-moderate turbulence and light-to-moderate rain and possibly hail. If we barged through and encountered a cell, we’d have a wild ride, and if it’s a cell just growing, young, and vigorous, we’d have a terrible ride. This has often been demonstrated by two airplanes going through a husky cold front on the same airway, same altitude, and perhaps only a half hour apart. One pilot says the ride was horrible, terrifying all the way. The second pilot looks a little doubtful and may think the first pilot an alarmist, because the second airplane’s ride had been pretty decent. The difference in rides wasn’t due to a

difference in fortitude between the pilots; it was simply that one missed the cells and the other didn’t.

What’s Outside All Those Clouds? It could be smooth, then suddenly a lot of turbulence, some as bad or worse than in a thunderstorm. It could be the air mass ahead of a front, cold air flowing out from a nearby storm, and many other possibilities. It often isn’t raining, so we do not see a radar return. This can be a real issue at night, as with no radar return or daylight to see what’s outside the windshield, one can be in for a great shock. One of the worst turbulence events I (ROB) have experienced was at night out of Albany, New York, in a Twin Otter, when flying for a small regional airline. We were headed for Saranac Lake in the Adirondack Mountains. There were some thunderstorms supposedly about 25 miles north of the airport, pretty much on our course. This was before NEXRAD, computer weather, and our radar was pretty anemic. Just after takeoff, there was some vague blob of yellow fuzz on the old black-and-white radar, about 15 miles away. Passing about 4,000 feet, still in the clear with good visibility, we hit turbulence that was equal to almost any thunderstorm cell. It hurled and twisted us on every axis. The captain told me to work the throttles, as he used both hands to fly. In what seemed like forever, but probably no more than about five minutes, we turned around, descended, and flew out the bottom of the turbulence, landing back at Albany. The rest of the evening was cancelled, as thunderstorms came into the area, shutting things down. Never were we in any clouds or rain; there were always lights of ground contact. When we shut down at the gate, all we could say was: “Where did that come from?!” Later, we visited the NWS facility and their only guess was outflow and a gust front from the oncoming weather, still quite a distance away. The moral is that we can find very bad turbulence outside a thunderstorm and that de Havilland builds good airplanes. Where we often learn, in textbook form, about airflow and turbulence inside, around, and outside thunderstorms, the most important thing to remember is that things aren’t always by the book, and we should approach thunderstorm weather as though we are walking on thin ice.

Thunderstorm Detection Systems This brings us to devices that allow us to look at thunderstorms from our aircraft. Today, this includes not just airborne—or onboard aircraft—radar, but also NEXRAD, from the nationwide National Weather Service Doppler Radar sites, that is transmitted to electronic aircraft displays or portable electronic devices. There are also devices that read thunderstorm electronic activity—lightning—and display these areas of lightning on instrumentation in the aircraft; there are various names for these systems, including spherics, lightning detection systems, and,

because they map lightning on a display, lightning mapping systems. We’ll call it Lightning Detection. For years, airborne radar was the only game in town, but many lighter general aviation aircraft could not fit or afford airborne radar. However, the advent of NEXRAD and Lightning Detection allows excellent information from which the masses can now avoid areas of convective weather. This availability reinforces the statement that we should never flirt with thunderstorms, especially at night and on instruments, without at least one of these three devices. This is especially true when we can display NEXRAD on personal electronic devices, whether on the ground or in an aircraft, giving us a very affordable visual look at what’s out there. The best of all possible worlds is combining some or all of these systems in the aircraft, which is now possible through the many combinations of electronic displays. However, each of these convective weather–seeking devices has advantages, disadvantages, and limitations in the information they provide, which we must understand for best usage, as well as for safety. We must also stress that the intricacies of each system must be studied and understood before using them in flight. To do otherwise is unproductive, distracting, and frankly could get us into more trouble than not. Most of all, we must have the discipline not to be mesmerized into thinking the information is 100 percent accurate. We’ll take a very basic look at each system, in lieu of definitive details, as there’s a book worth of information on each one. However, before doing so, let’s chat about some basic points of dealing with convective weather, applicable to all of these systems. We want to use our radar for a look at the thunderstorms as far in advance as possible. We then attempt to fly around the entire area, or the biggest area of cell congestion, rather than getting in close and using airborne radar to squirm between cells. A good look, with planning in advance, can mean missing the entire mess. NEXRAD does nice work here, because it looks at weather from above, along with coverage that can literally be nationwide down to local, so we have superb strategic-planning ability. Lightning Detection also gives us an overhead, area-to-avoid scenario. There are more advantages to reading any radar picture in advance of reaching an area of thunderstorms. For one, it allows time to tell ATC what kinds of headings are desired to circumnavigate the weather, well in advance of arriving in the area, when we very possibly have to compete with everyone else doing the same thing. (Also, we are saving miles, hence time and fuel, by making that diversion far away, instead of making a longer mileage jog up close.) In any event, ATC will be in a much better position to cooperate and give the needed course changes. Another point is that once in close to the cells, all will not be easy. New cells tend to generate close to old cells, so being in an area of cells, and close to them,

means that more will develop, and getting through it all without getting roughed up, even with tactical use of airborne radar, isn’t going to be easy. Being in close to the cells doesn’t give much room to avoid them by the respectable distances that good procedures dictate; we’ll talk about that in a moment. But all in all, the best way to use either airborne radar, lightning detection or NEXRAD is to duck the entire area. Remembering that any kind of radar or lightning detection is a device to help us miss cells, with airborne radar more capable in close, it’s apparent that when radar fails to show storms, it’s a useless device. All radar and lightning detection is fallible; there are times when it doesn’t do the job, and we’ll talk about them here. Before we do, however, let’s make a point clear: if we are going to enter a thunderstorm area, depending on radar or lightning detection to lead us through without getting into a cell, odds are we had better be able and willing to fly through a cell. However, putting ourselves in this predicament is not a good idea, especially in a light aircraft; past history shows that over half who do so don’t come out in one piece. Radar and lightning detection will take us places we should never go without it. Suppose we get into this forbidding place and the radar or detection system fails; now what? Real simply, we are either lucky and fly through without running into a cell, or we bang into one. If we hit one, let’s hope both we and the airplane can handle it! Another area that we need to stay away from, while sneaking around thunderstorms, is under the higher-altitude “blow-off” clouds on the downwind side of a thunderstorm. Even though it is clear, and you can see around the storm, and on to happy storm-free skies, it’s a sucker area, where hail is apt to be, and often clear-air turbulence as well. In a confused mass of cells and, of course, at night, we cannot see this area. The blow-off drifts a long way downstream, so a rule is: avoid a cell’s downwind side, go around on the upwind side, and clear it by one nautical mile for each knot of wind at the flight level. That may be a lot of miles, but it’s worth all of them. These wags are well known and heeded by many. One day, while deviating around a vivid thunderstorm southeast of Kansas City, Missouri, the upwind side to the weather was south, with not much wind aloft. We (ROB and son COB) were low, in our Cessna 170, with a few other light aircraft sharing the same deviation. As we listened to ATC Flight Following, a turboprop was deviating south as well, pretty much above us at middle altitudes, and way up high, also above us, a contrail showed a jet changing its course to avoid their high-altitude needs of storm avoidance. The moment was a great lesson on how these basic rules of sky and airplane work. While it is best to go around on the upwind side and avoid the downwind blow-off area, one should not just skim by the cell on the upwind side, because there is wind shear in the area caused by a speeding up of the wind close to the cell. That means turbulence. Give the cell wide berth, and remember the rule of

one mile for each knot of wind at your level. However, there is no definitive criterion that guarantees what will happen, so again we must be prepared for surprises.

Airborne Radar This system, installed onboard an aircraft, sends out a “beam,” which is more like a skinny cone-shaped signal, that bounces off precipitation—rain—as well as ground, and returns to our aircraft, being displayed on an electronic screen. The response time is, for practical matters, instantaneous, so what we see on a radar screen is not delayed. (This is very important when comparing to NEXRAD, which has time delay in its signal.) The signal is sent from a round, plate-like antenna, looking flat-side forward, mounted in the nose of an aircraft or sometimes in a pod on the wing. The bigger the antenna, the farther and more accurately we can see weather, which is more of an advantage for big airplanes. The range of these systems can be adjusted from as little as five miles ahead to usually no more than 320 miles on bigger systems, with smaller ones usually 100 miles or less. The antenna searches left–right, in a 90° to 180° range. To deal with a combination of aircraft and cloud height, as well as signals bouncing off the ground, a pilot can control the up-and-down “tilt” of the left– right searching antenna. This allows analysis of weather through a broad range of storm and airplane heights. So, with airborne radar, we have an excellent way of seeing the cells and avoiding them, although it takes learning, experience, and radar equipment in good condition. We should never be on instruments when tactically weaving about nearby thunderstorms, unless we have airborne radar and know how to use it. Airborne radar is a tremendous aid in thunderstorm avoidance. What it does is let us see cells on a screen that we cannot see by eye, because of other clouds and darkness. How does it do this? The signal is reflecting off the rain inside the cell. However, radar isn’t a total cure, because it is not showing all turbulence, instead only that which is associated with rain. There’s lots of turbulence, often the most severe, outside the rain area! So it’s showing us a “core” of problems surrounded by turbulence, but the turbulence not shown is something we cannot discern. We have to “guess” how far away to stay. So, schooling and experience is needed to get the most from radar; one just doesn’t buy one, turn it on, and go fly thunderstorms. We strongly recommend that you attend one of the seminars or radar-schools available, or at least use a home-study curriculum on how to use radar before going out and trying it. However, a classroom environment with experienced instructors is very important for picking through the nitty-gritty of this delicate art; but the best classroom is flying in an airplane with a good radar system, around real live thunderstorms, with a pilot-mentor who is very experienced in this fine-art.

The fact that airborne radar bounces off rain also causes a problem, in that it bounces off the rain of a cell ahead but doesn’t always get through that cell to reveal one just behind it; the signal is attenuated (weakened). The stronger the initial cell we are looking at, the more it can attenuate. What does that boil down to? Example: we are avoiding a cell the radar shows and go around it, only to find that, when turning the corner, there’s another cell, or cells, facing us. It’s a great way to get trapped in a blind alley of thunderstorms, the only way out being to fly through one of them! Modern airborne radars have tried to improve on this, but systems that offer improvement are still usually for larger aircraft and quite expensive. Here, if we can augment our airborne radar system with NEXRAD, we now look down on the weather, which helps us see what is behind the cell that might be causing attenuation. Also, the use of a Lightning Detection can do the same thing, but only if there is lightning being registered from the farther storm. Radar’s important feature is that it reflects from rain, but at high altitudes, the cloud doesn’t have rain. It has snow and ice crystals instead, and sometimes hail. We can find, on occasion, “wet hail”—hail not totally frozen in that it has a coating of water outside its frozen core—which along with any rain thrust high in strong lift, will give some reflection. However, up high we’re usually in frozen precipitation, and the radar beam doesn’t reflect as well from this frozen stuff, and the cell becomes difficult to see on the screen. The way to try and overcome this is to point the antenna down toward the rain area for a picture. The trouble is that airborne radar then bounces off the ground too, the picture becomes confused, and individual storms are more difficult to see, in that they show as blobs amidst ground “clutter” on the screen, with a dark area behind known as a “shadow.” It takes a lot of experience to read a scope under these conditions, and even with experience, it doesn’t always work. To help the ground clutter issue, if we know the terrain and rough distances from it as we are flying along, we can anticipate mountains, valleys, cities, and bodies of water that allow us to anticipate what is ground clutter and what is not. New radars are just coming into play that use GPS information to know where we are, and along with vastly improved computerized and automatic antenna tilting, figure in terrain and help alleviate attenuation problems. It’s new, but an excellent improvement. Airborne radar maintenance problems are not always just a simple matter of whether the radar works or not. There are degrees of radar maintenance, and this makes thunderstorm reading difficult and less clear. The radome itself, its special paints and coatings and structural condition, also play into this equation. It is necessary to get all the information possible from the manufacturer and learn to recognize when radar equipment is not putting out its best performance. There are various ways of doing this; one is to note how much “gain” (signal strength) the system requires for a picture. However, this is best learned for each system we operate. If we do turn down gain, which for example can be used to verify a storm’s intensity, we must remember to return it to normal position, as

forgetting about it can hide weather we may need to see, consequently running us into a cell that the radar couldn’t detect at the lower signal strength. Let’s list some airborne radar limitations: 1. 2. 3. 4. 5. 6. 7. 8.

Failure. Equipment deterioration. Attenuation. Poor reflection from frozen particles. Difficulty reading in mountainous terrain. Pilot experience with radar. Radar only shows rain areas. Ice or damage on a radome causes false or poorly defined targets.

An important point is the general guide that most professional flying operations use in determining how to miss cells. It’s based on temperature and altitude. They say to miss cells, when using airborne radar, by the following distances: • When the temperature is above freezing—5 miles • Temperature below freezing—10 miles • At altitudes above 25,000 feet—20 miles Also, the above are minimums, and it’s better to give the cells a wider berth if possible; 20 miles minimum, at all times, which can also be considered for NEXRAD and lightning detection systems. If a thunderstorm is approaching the severe category—which the weather service defines as 50 knots of surface wind and ¾-inch hail—we should consider a 50-mile deviation. Again, remember that radar only shows rain areas, and even the new radars that boast turbulence detection by use of Doppler techniques are only telling you whether a rain area is turbulent or not and how much. It isn’t revealing anything about the turbulence outside the rain area, where some very tough stuff can lurk.

NEXRAD NEXRAD, the acronym for the National Weather Service’s NEXt Generation RADar, is convective weather information homogenized from, as of this writing, 155 WSR-88D Doppler radars at NWS facilities across the United States. These radars read precipitation rate, measured in decibels (dBZ or dB) between zero to 75, and are presented as 16 levels of dBZ, as well as in color. NEXRAD data also shows velocity and direction of convective weather, and sometimes storm height, and that, along with the dBZ color criterion mentioned above, is what we mostly use in aviation. As previously mentioned, we remember

the orientation of NEXRAD is as if we are looking down on a weather map, rather than horizontally ahead, as in airborne radar. We again recall that precipitation rate is not a definitive measurement of storm intensity, with a severe thunderstorm requiring at least that 50 knots of wind and ¾-inch of hail or a tornado. However, a lot can happen that will make flying miserable or maybe impossible, including microbursts, without a thunderstorm being rated as severe. NEXRAD has a lot of other modes we don’t use in aviation, but that weather services use to analyze the sky. It is the system for ground-based thunderstorm evaluation, whether for aviation or the many other concerns the weather service uses radar to detect. Also, where we think of radar showing thunderstorm information, NEXRAD picks up rain in all sky-conditions, so it could be precipitation out of a far more mundane weather situation. Hence, another reason we have to understand weather systems, so we know what NEXRAD is looking at. With recent upgrades to what is called dual polarization, it allows better detection of freezing levels (which could help us in aviation with respect to icing), wind analysis, severe weather issues, and more. A mode we can see on the NWS website is Relative Velocity, which leaves out a storm’s movement over the ground, instead exhibiting the storm’s internal directions, which is helpful when looking for tornados, among other things. NEXRAD can even see swarms of birds, bats, insects, and sometimes windmill farms giving false vorticity/tornado indications from the complex airflow around them. As we fiddle with NEXRAD in aviation, it’s worth remembering that weather service folks take months of training to learn these systems; something to ponder should we get heady in thinking we are experts in using NEXRAD. The process of creating the mosaics of NEXRAD entails collecting each individual radar’s return, sending it to and through computerized processing, then transmitting it through services to our viewing preference: television, computers, personal electronic devices, or an aircraft’s instrument display. This processing of radar data takes time, sometimes nearing 10 minutes or more, from when local radar sites begin to process what we are looking at in an airplane. This time delay is very important to remember, especially in comparison with airborne radar’s instantaneous presentation of convective weather. The obvious big gain to aviation from NEXRAD is not only do we get an efficient radar display for preflight planning and trend analysis, we also can use it in the air, which pre-NEXRAD was only the lofty world of those privy to airborne radar. But as we said, there are limitations and knowledge we need to fully know and understand before smugly heading off into a sky full of weather. The delay issue of NEXRAD information is probably the most important restricting feature of the product. This is why NEXRAD is best used in strategic avoidance of weather—avoiding the whole area in lieu of closely sneaking around cells, which, if you have to and as mentioned before, is better done with airborne

radar’s instantaneous information. The reason is simple: the delayed presentation can have a thunderstorm farther downwind than the radar shows, and if at night or in cloud, you can run into it. For example, if a cell is moving at 30 knots and we assume a 10 or more minute delay of the NEXRAD data, the cell is a minimum of five nautical miles farther along. If we are closely deviating around this weather, on the downwind side for some unfortunate reason, we may run smack into the cell. So, when using NEXRAD around convective weather, the time delay makes it even more important to deviate on the upwind side. However, in an area of thunderstorms, even upwind, we can have another storm right behind the upwind side of the one we are avoiding. Most dedicated NEXRAD displays show time-delay information, but it is not —at least as of now—the total delay amount. It shows only the delay between transmitted data and not for the whole process if creating the NEXRAD mosaic. So, for example, looking at two minutes on a screen may actually be that 10 minutes or more we mentioned above. This example is taken from a fatal accident, where the pilot was downwind of convective weather moving at 45 knots and ran into a thunderstorm cell, where the aircraft came apart. In that accident’s case, a turn away would have cleared the whole thin line of the area, where the pilot could have either found broad space to pass by the weather or to land somewhere safe until the weather passed. This is not the only incident, and enough have occurred for the National Transportation Safety Board (NTSB) to issue a Safety Alert in 2012, warning about the NEXRAD time delay, although many had realized and warned of this before the NTSB Safety Alert. Another aspect of NEXRAD is the type of radar search data that is presented. The search that sees precipitation, hence convective weather, is “Base” and “Composite” reflectivity. Reflectivity refers to the radar mode that reflects off rain. Base reflectivity means the radar searches at a low angle with the beam center at a half of a degree above the horizon. It’s a more concise signal, doing a very good job of reading a storm’s intensity and movement. Some base reflectivity mosaics might underestimate a storm’s intensity. If interrogating a rain-bearing cumulus or thunderstorm thousands of feet high, this dedicated beam slices through only part of it, and depending at what height the heaviest rain is located, may miss this precipitation altogether. Or, it could go under or over the storm altogether, depending how far away the storm is located from the ground-based radar facility. Composite reflectivity interrogates by taking multiple beam scans of the sky, between half a degree up to 19½°, allowing a look at a storm in a vertical column. It’s a more three-dimensional view of reflectivity, giving a more complete view of a storm’s precipitation. Composite reflectivity can overestimate a storm, but this more complete look at the storms development, hence structure, can indicate storm severity that otherwise would not show in a base reflectivity image.

Consequently, one needs to take the conservative view and consider any NEXRAD indication of precipitation, in a potential thunderstorm area, as the real deal and a place to avoid. An important area where base or composite scans can make a difference is in mountainous terrain, and particularly in high mountains. Terrain will stop any radar signal dead in its tracks, hiding precipitation returns that could be very important for us to see. This effect is more susceptible to base reflectivity, because it’s a low beam, but can happen with composite if faced with really tall terrain and weather a fair distance behind it. A great example is looking at the Burlington, Vermont, NWS NEXRAD site on a day there is precipitation to the east, where about 20 miles away the Green Mountains stretch north and south. Base reflectivity will show little or no precipitation east of the 3,500-to 4,000-foot mountains. That is a real setup as we happily head off over the mountains, only to bash into weather that had its rain hidden from the blocked radar signal. To get the best idea of what a storm area is up to, we should compare base and composite reflectivity. This gives us a more thorough look at the weather. One important variation is the more sensitive read of precipitation in composite scan which could mean serious issues developing such as high-level hail or a potential microburst that, before long, may be pouring out of the storm. Overall, it could expose a thunderstorm issue far more intense than previously thought, but then again, we should consider all thunderstorms as something to avoid. At this point, it’s important to confuse the issue and point out that having a choice of seeing base or composite reflectivity is usually a function of looking at radar data from weather sources such as the NWS ADDS site. You can switch between base, composite, static, or looping mode. However, when we receive radar information through a weather source, be it data link to our aircraft, a personal electronic device, or TV, we are usually offered only one reflectivity: base or composite. It is important we understand what we are looking at and make the necessary compensation for how the NEXRAD mosaic is presented.

Base Reflectivity NEXRAD image, with its low half-degree beam, from Burlington, Vermont. Note the weather’s farthest eastern reach stops about Middlebury in central Vermont, up against the Green Mountains, the highest of which is about 4,000 feet. (Refer to composite reflectivity image below.) On some of the more dedicated aircraft presentations of NEXRAD, other bits of data will be available, such as storm direction, intensity, possible tornado activity, lightning, and echo (cloud) tops among others. This data comes from other analysis of NEXRAD by the NWS and other sources. It is then packaged with the data-linked weather for our aircraft. These highlighting enhancements should provide further impetus for us to avoid the whole area and not weave through it. Also, in referring the dBZ ratings of precipitation rate, anything over 40 dBZ is considered something we really need to avoid, and if we see colors relating to over 60 dBZ, that is when we are looking at potential hail or microburst. In reality, few if any aircraft NEXRAD systems, let alone the majority of pilots’ amateur use of this equipment, either airborne or ground-based, will allow us to analyze if there is hail, microbursts, certain turbulence levels or

whatever. And if we see dBZ ratings of any level, knowing it’s an area of thunderstorm potential, in lieu of an area producing non-convective rain, we need to avoid the area. Again, if a Cb is developing, but not yet raining or raining of light intensity, it can still give us a wild ride. Radar is not the whole story!

Composite Reflectivity from Burlington, Vermont, with its higher radar scans, at the same time as the base reflectivity image above. Now we find out there is activity over and beyond the mountains to the east. Taking off at night or in cloud IFR, heading east, thinking no weather was beyond the mountains, we could be in for a real surprise! Lastly, when NEXRAD system data is presented to us, its smallest resolution is a little two-kilometer square on the mosaic presentation. So if we have a radar display that can hone in real close, we’ll see little two-kilometer squares and nothing tighter. A lot can happen in that little square, including things like a microburst that can knock us flat out of the sky. Let’s list some NEXRAD limitations:

1. Time delay in NEXRAD mosaic presentation causing false assumption of the weather’s position. 2. Terrain blockage of signal can miss or underestimate important storm data. 3. Should know the type of reflective signal, base or composite, and respective limits. 4. Mosaic accuracy is no smaller than a two-kilometer square. 5. Lost signal possibilities. 6. Pilot experience with NEXRAD 7. Only shows storm precipitation.

Lightning Detection Systems Before radar, we avoided thunderstorms by experience, witchcraft, and tricks. We didn’t avoid all of them, because we couldn’t “see” the cells, so we unknowingly flew through them, from time to time experiencing very rough rides, and we lost airplanes, too. Coming up on a line of thunderstorms, we’d watch the lightning closely and try to avoid going into the mass of clouds where the lightning was “hot.” It didn’t always work, because the lightning frequently seemed to cover the sky due to reflection within clouds and the general bombardment. We also tried to tune our ADFs to a low frequency, away from any station, and then watch the needle, thinking it was pointing out thunderstorms and where not to go. Some claimed considerable success with this technique. My own success was of very low order, and I (RNB) never thought much of the idea. We looked up to the tops, picked the lowest, and went through under that. For a time there was a theory that flying through the heaviest rain was the smoothest way, but that didn’t work either. One thing we all agreed on was not to land or take off with a thunderstorm near or on the airport. Decades later, research found these basic “gut-thinking” rules had validity. It was revealed the intensity of updrafts and electrical power increase exponentially with storm height. We have also learned that landing and taking off in thunderstorms is not only unwise due to violent turbulence, including excessive vertical air currents, but also due to wind, heavy rain, and disastrous microbursts. A few decades back, Paul Ryan of Ohio was flying his Cessna Skylane across one of the Carolinas when he tangled with a thunderstorm that almost did him in. The turbulence was wild, and he felt lucky to get through it alive. Mr. Ryan, an electrical engineer, decided that something needed to be done about thunderstorms and avoidance for the single-engine “little guys” of aviation, because most couldn’t afford radar, and even if they could, installing a radome on a small singleengine aircraft was a unique challenge. He started, much as we did, with ADFs and eyes, to “see” the electrical discharges—lightning—that go with all thunderstorms. After much research and

development, he created what’s now known as Stormscope. This device reads the electrical discharges (lightning) and displays them either on a dedicated distance and direction display or on electronic instrumentation of aircraft so equipped. The ideal situation is when we can compare this lightning data with other weather and navigation information. Unlike airborne radar, there are no movable antennas or radome, rather, just a small, fixed antenna and the instrument panel display showing “+,” “x,” little lightning bolts or dots and colors—depending on the system and intensity—that are electrical discharges, hence thunderstorms. Also, the lightning data can often be displayed through a 360° range, so one can “see” the storms all around before takeoff, which can be very handy. Along with Stormscope, here came a competitor called Strike Finder, and now, years later, we have further iterations of this technology through various avionic manufacturers. The technology detects and displays lightning, indicating convective weather to be avoided. This science is really a lightning detection system that maps the lightning on a display, and another term for the often used spherics or sferics— a word derived from radio atmospherics. Most accurately, it is a lightning mapping system, but that term is also used for systems that display lightning derived from a long-range, ground-based detection network, which we’ll talk about after this section. So, in some hope of commonality, we’ll refer to this type of unit, formally known as sferics, as a Lightning Detection System (LDS ).

An actual in-flight, split-screen MFD display of lightning detection (left) and NEXRAD (right) for the same time and place: heading north–northwest on 200mile scale at 8,018 feet. Dots at the top of the right split screen are airports. On the left split screen are “X’s” indicating lightning/thunderstorm activity, but NEXRAD shows nothing in the same area, except a 20,000-foot precipitation

return. Fifteen minutes after this picture was taken (second image unavailable), more precipitation appeared in the “X” area. These time differences are indicative of NEXRAD delay issues. The large precipitation area in the NEXRAD image’s lower right shows no lightning, for whatever reason, but with 30,000-foot tops, moving over 30 knots, it is a place to avoid. Overall, we see the benefit of having both lightning detection and NEXRAD—the only thing better would be adding airborne weather radar. Most important is realizing all the variables make weather “strategic” deviation—avoiding the whole mess—the prudent choice. (PHOTO COURTESY OF L-3 AVIONICS SYSTEMS) In basic explanation of how lightning detection works, we are going to refer between two basic types of lightning: Cloud-to-Ground (CG ), its nature being obvious by name, and Intracloud (IC ), again pretty obvious as to where it lives. These two types of lightning tell us different stories. Research has shown that intracloud lightning begins early in a storm’s development, often as much as 10 to 30 minutes before cloud-to-ground lightning. Also, intracloud lightning can be active as much as 10 minutes or so after the cloud-to-ground lightning stops. Intracloud lightning generally occurs more frequently than cloud-to-ground, sometimes upward of ten times. So in theory, intracloud lightning is well in place during the earlier and more intense, updraft development phase of a thunderstorm, often before significant rain begins. And we remember rain is required to show weather on radar. Now when a lightning detection system shows lightning, we must consider it as a real thunderstorm, and should avoid the area. There is debate, however, as to how early in a storm’s development we are seeing it. This is because lightning detection systems are seeing, as a majority, only the later cloud-to-ground lightning, as they supposedly only work at the very low frequencies of cloud-toground lightning’s radiation. Intracloud lightning is of higher frequency radiation, which can sometimes be picked up randomly if we are really close to an area of lightning. What this all means is that if we are not receiving indication of the earlier intracloud lightning, then we are also not seeing a thunderstorm in its early, developmental stage, which can be that most turbulent time. Hence, like any thunderstorm detection system—radar or lightning—we do not have total guarantee of avoiding all related turbulence and everything that goes with it. However, no matter the issues mentioned above, lightning detection is a very sensitive indicator of storm activity, so a real key is lightning rate; if there’s a high lightning rate, the storm has serious clout, and we should absolutely stay away . In reality, any lightning means a thunderstorm, and we should avoid it no matter the intensity. Lightning detection systems also offer accurate azimuth (direction), but can vary in distance accuracy. This latter issue is called “radial spread.” It’s caused by what we see as one lightning strike really having multiple strokes of lightning

during that supposed single strike. The strokes can vary in intensity, so a weak stroke seems far away and a strong one close by. Also, a lightning signal’s “bounce” can be affected by bouncing off the ionosphere, kind of like an AM radio station, where you hear a station 1,000 miles away at night, but not in the day. As lightning detection systems must make assumptions of cell strength from the data received, there can be variations in distance accuracy, but supposedly, newer systems have modes where algorithmic software improves this issue of radial spread. A lightning detection system aircraft installation can, on occasion, show lightning display that isn’t from lightning, but instead things like an airport’s underground electrical lines, say for runway lights, or strobe lights in the air. This is of minimal concern versus the benefit of lightning detection, but a quandary if looking at lightning data on our detection screen, before we takeoff in suspiciously clear air. Manufacturers of these systems are claiming dramatic improvements of detection capability, and these systems often see lightning a fair time before radar, hence rain, which is also usually when cloud-to-ground lightning is prevalent, so one wonders what’s really being detected as to CG and/or IC lightning. If there is eventually an airborne system that accurately reads both intracloud and cloud-to-ground lighting—referred to as total lightning—we’d have a pretty exciting system. There are ground-based versions of this today, but they are only used in specific situations or are not adequately promoted for their potential benefit. However, even if a ground system became available to aviation, we’re probably back into a NEXRAD-style “ground to eventually airplane” transmission delay issue, which, with total lightning’s benefit of showing rapid storm change, kind of reduces the benefit of the whole idea. With an aircraft installed system, which has appropriate calibrations and indications, we’d possibly have, for the first time, a system to sense the excessive turbulence in developing thunderstorms, before rain is visible either by eye or radar; a potentially helpful new addition to tactical weather avoidance There are also indications that total lightning may give accurate prediction of microburst and tornado activity. A last point is that as intracloud lightning trails on a bit after the CG lightning ends, so we’d potentially avoid a late in the event surprise of unwanted turbulence. But again, as no lightning detection system has definitively shown data that proves their system can always detect both intracloud and cloudto-ground lightning, we must assume these are not full total lightning systems. The obvious big benefit of lightning detection systems is that without any form of radar on our aircraft, either airborne or NEXRAD, lightning detection is our ace in the hole. If our aircraft has a combination of airborne weather radar and lightning detection, but no NEXRAD, the lightning detection system will have considerably more range than all but the best airborne radars being flown at high jet altitudes. The obvious benefit here is excellent advance warning of weather

and subsequent long-range planning of deviation. Also, as said before, with this convective weather detection combination, lightning detection lets us see around airborne weather radar’s attenuation; we recall that attenuation is where a cell painted on airborne radar blocks detection of further weather behind that cell. If we have confusion on airborne radar between weather and ground return, lightning detection can help us decipher what’s weather and what isn’t, which is especially helpful in mountainous terrain. Going back to NEXRAD, there are places where the NEXRAD system does not offer coverage, be it beam blockage from terrain, the NEXRAD mosaic being out of range of radar facilities, or distant parts of the world where no such system exists. The NEXRAD data may suddenly end, deceivingly allowing us to think any convective weather did the same. However, because lightning detection is aircraft-specific, it will still show convective weather out of NEXRAD’s reach, which could really save our bacon. Of course, airborne weather radar will do the same, but that is the only commonality between airborne weather radar and lightning detection: they are working from the aircraft and are not ground system– dependent. Now if we have lightning detection, airborne weather radar, and NEXRAD onboard, we can work these systems as complements to each other for excellent convective weather avoidance. Because radar reveals the rain area and, one thinks, turbulence, radar leads us around the rain, hence supposedly the turbulence. Lightning detection shows the lightning, which says the rain is a real thunderstorm and we should stay out. If we see lightning detection data outside a rain area seen on radar again, that’s a place to avoid. In theory, if there is rain but no lightning return, it isn’t a thunderstorm, saying there’s little or no turbulence in that rain, awful though it may look. Numerous tales are told of pilots seeing dark, foreboding rain, but Stormscope or Strike Finder not showing lightning. Brave souls have flown through these areas and had good rides. Similar stories are told of paralleling a front that looked mean, nasty, and impenetrable, but these systems showed an area without electrical discharge and a way though. However, like so much of aviation weather, this is not a 100 percent perfect solution, so all such events should be approached with caution, experience, and common sense. Putting all this together, it seems that if a lightning detection system is showing us lightning, the storm is the real deal, and we should avoid it accordingly, which is the most conservative—and sensible—choice. So where does it come out? Lightning detection no doubt shows the location of thunderstorms and can help us avoid the storms, but not closely enough to weave through a mass or line of them, unless a clear, wide path is revealed. Ideally one would like to have lightning detection, airborne radar, and NEXRAD merged together on one display. Some people have remarked that they use lightning detection more than airborne radar. Lightning Detection Systems are there for all aircraft, but are an especially helpful option for single-engine and less

expensive aircraft. This is lightning detection’s role. We can be thankful that Paul Ryan took the initiative after his thunderstorm encounter and did something about it. As with all convective weather detection devices, be it radar or lightning detection systems, there are pros and cons that can get us in trouble no matter the system. In using these systems, we need to understand how they work, how to use them, and the quirks each will have in their individual installations. As said earlier, and certainly worth repeating, any of these devices should ultimately be used to avoid the areas of convective weather, when at all possible, and lightning detection systems are a very worthy player in convective weather avoidance. Let’s list some Lightning Detection System limitations: 1. Use in weather area avoidance, not for close-in tactical weaving. 2. Systems only show lightning data, not precipitation. 3. The systems only show mostly cloud-to-ground lighting, which occurs later in a storm’s development than intracloud lightning, hence still not consistently revealing early and turbulent storm development. 4. Pilot must be familiar with each aircraft-specific lightning detection system installation, both with the system in general and effects due to aircraft installation.

Data-Linked Lightning Mapping Information We need to understand that Lightning Detection Systems should not be confused with lightning information that is data-linked or vendor-supplied for display on an aircraft multi-function display, GPS unit or portable electronic device. As said earlier, this data comes from other lightning detection sources, including the National Lightning Detection Network, and is cloud-to-ground lightning data. This is the lightning information most colloquially related to the term “lightning mapping.” This data is displayed like NEXRAD, so we are looking at it from above as we fly along, unlike lightning detection systems or airborne weather radar, which is from the aircraft. Lightning mapping, as shown on aircraft data link, is also subject to NEXRAD-style time delays, but the delays are not as long due to quicker processing of multiple data feeds. Since lightning mapping information is cloud-to-ground lightning, like the lightning detection system onboard our aircraft, we approach it with the same understandings of what cloud-to-ground lightning tells us of a storm. Like our aircraft-installed lightning detection device, there is a worthy use for this information, and usually when we’re using lightning mapping, we have other information displayed, such as NEXRAD, satellite data, and so on. Another benefit is this lightning data covers a broader area than NEXRAD, again giving us

an indication of convection should NEXRAD be out of range or unavailable. What we often see displayed through data-linked lightning mapping and vendor lightning data are little lightning bolts on our display, and wherever they are present, even if isolated from radar data, we should fly clear of the area. A Summary of Convective Weather Detection 1. Even with airborne radar, NEXRAD, and/or lightning detection systems, don’t fly into cloud areas containing embedded thunderstorms, especially if you can avoid them in the first place. 2. If in cloud or darkness, and avoiding thunderstorms with any avoidance system, give them as wide a berth as possible. Don’t just skim around the edge of cells; use at least the minimum mileage rules. 3. It’s best not to think light precipitation in the vicinity of known thunderstorms is not too bad. If the storm is growing, it can change very fast. They are all thunderstorms; some are just worse than others, but we can never be sure how bad … until we are in them. 4. Know your geography; terrain knowledge allows an understanding of what airborne radar may see as ground clutter and what NEXRAD does not see due to beam blockage caused by terrain. 5. Take courses and/or seminars on each thunderstorm detection device we use, then practice and stay current. 6. Look out the windshield; learn to visually evaluate convective weather, especially as it develops to thunderstorms, not only the storm’s character and state of life, but the direction it is moving. As those old-timers would say, thinking of that airborne radar antenna sweeping back and forth: “One look is worth 1000 sweeps.”

ATC and Thunderstorms Thunderstorm intensity is graded for ATC purposes. The four terms “light,” “moderate,” “heavy,” and “extreme” are used when ATC tells us what they see on their weather information. Air Route Traffic Control Center (ARTCC ), which is enroute or center ATC, only gives moderate through extreme, not light precipitation. Terminal Route Approach Control (TRACON ) facilities, which are local airport (approach and departure) control facilities, give all four. These four terms are honed down from the 16 dBZ levels of precipitation intensity , previously discussed as NEXRAD’s measurement and display of weather. ATC’s weather data is collected from NEXRAD and is also subject to the processing delay and other issues. But overall, there is improved convective weather presentation on ATC radar, and controllers are better equipped to help pilots. As a majority, ATC controllers seem very concerned about and accommodating of our

weather needs. The four levels of precipitation, in relation to dBZ, are as follows:

Weather radar echo intensity

dBZ level

Light Moderate Heavy Extreme

< 30 dBZ 30–40 dBZ > 40–50 dBZ 50+ dBZ

There are still some potentially misleading aspects of the system that need be understood and taken into consideration. For example, what ATC may call light precipitation can be in a cumulus that’s just about to become a full-blown thunderstorm, rapidly increasing to heavy or extreme when it suddenly dumps its water. Remember, the rain area of a thunderstorm is not the only place severe turbulence can be found. A situation that can be misleading is being told something like: “an aircraft ahead of you went through that area of light precipitation and had a good ride.” If things were quickly moving and growing, we could have a real surprise. What would improve this system of ATC weather information would be a trend of the weather’s status; for example, light precipitation with increasing areas of moderate precipitation, and so forth. This is tough to do from ATC weather information and would have to come as supplemental information. There are inhouse NWS meteorologists at ATC facilities who can be consulted, but again, the time for discussing and introducing this information to aircraft is limited to traffic level. Ultimately, we as pilots need to have a feel for the weather we are dealing with, such as if it is isolated, air-mass thunderstorms or a more serious frontal/squall-line situation. This, of course, is necessary not only in our preflight briefings, but by following weather en route. With respect to the ATC system, a controller’s primary job is air traffic separation, in an ever busier sky. They are not required—and sometimes do not have the time—to volunteer weather information. If we, as pilots, need this assistance, we should let ATC know. Remember, they do not know our experience level or needs unless we tell them. In the case of thunderstorms, it might be vectors out of weather, an altitude change, and so on. If ATC can’t comply without our declaring an emergency, then we may have to do so; it’s better than putting ourselves up against a wall. However, we should strive to make sensible and well-planned flight decisions ahead of time and not use a declaration of emergency as a crutch. Unless a pilot understands the workings of thunderstorms and radar and ATC’s

limitations, this dissemination of thunderstorm intensity levels can be misleading, creating further hazards, rather than avoiding them. The information should be used with caution and respect.

More about Air-Mass Thunderstorms We were talking about air-mass thunderstorms; it’s important to realize that these come in several different kinds. The simplest is the convective kind. They are an eventual development from a thermal source, a hot spot on the earth. Obviously, when the sun goes down, the heating does too, and the storm dissipates. If it doesn’t, then the storm isn’t just a convective storm; something else is creating it. The real thermal convective storm may take a while to die and doesn’t disappear as soon as the sun goes down; a big bunch of clouds hangs on into the darkness with an occasional flicker of lightning, but it’s on its way out, and one can see and feel that it isn’t holding or increasing in strength. Thermal convective storms are easy to run around when they are scattered or isolated. Sometimes, however, they aren’t so scattered. Whether they are scattered or broken depends on how much moisture is in the air mass and how unstable it is. This is pretty difficult for a pilot to judge, except that forecasts give an idea simply by the number of storms they predict. Our old friend the temperature– dewpoint spread is another indicator; if the dewpoint is high, the air is moist and more likely to produce storms. You can “feel” this too, and because weather appraisal is inexact to begin with, one shouldn’t laugh off old sayings like those about rheumatism that hurts when it’s going to rain. On a hot, muggy summer day, any weather-conscious person can sniff the likelihood of storms. We are still basically animals, and despite years of sophisticated city living and separation from the primitive state, we have a feel for weather, feeling it in our bones, as the saying goes. Naturally, we don’t use instinct for our basic weather judgment. Science is the important thing, but that old instinct is worth using, particularly when it raises suspicions that all is not as good as a forecast may say it will be.

A Cloud Base Hint Incidentally, temperature–dewpoint can help in finding the base of cumulus clouds, or how high one will have to climb to get up out of the lower-level convection. Take the temperature–dewpoint difference in degrees Celsius and multiply it by 400. The answer is the altitude above the ground, in thousands of feet. For example: temperature = 35 degrees, dewpoint = 20 degrees. The difference is 15 degrees. This times 400 is 6,000. The base of the cumulus will be about 6,000 feet. (If dealing with degrees Fahrenheit, obtain temperature– dewpoint difference times 2, plus about 400 feet for the bases. For example:

temperature = 93 degrees, dewpoint = 67 degrees, difference = 26 degrees; 26 × 2 (add two zeros) = 52(00) + 400 feet makes the bases about 5,600 feet.) That’s one reason, during the day, cloud bases are lower over valleys and higher over hills and mountains.

Other Air-Mass Thunderstorms To sum up, air-mass thunderstorms are generally isolated and occur in the afternoon, when heating has had a chance to work on them. They can also occur in overrunning air, not necessarily from a warm front, but from slopes acting like a warm front. This will carry thunderstorms into the night, but probably their bases will be high. Air-mass thunderstorms can bunch up and look like a front, but we can generally fly around them. In the parts of the world where visibility is good, such as in the far western United States, this is easy. In the more moist sections, where haze reduces visibility, it’s more difficult; a pilot is best on top of the haze level, where the cumulus buildups can be seen. It’s important, of course, not to get trapped on top when doing this. It is also important not to try to top thunderstorms. As said before, it’s dangerous to sneak around underneath high, overhanging anvil clouds, because that’s where hail falls from. It falls more outside the storm than inside it. It is dangerous to sneak under thunderstorms where visibility is reduced and there’s a chance of flying abruptly into clouds, rain, and turbulence. Mountains may be buried in the haze, too, as are communications and other types of towers. Also, if a pilot runs into turbulence down very low, the situation is more hazardous than flying a bit higher, where there is room to wrestle the rough air. While trying to get past a line of thunderstorms when flying down low, we sometimes see the clear-cut black edge of the storm’s base, but then beyond, happily, the pleasant sight of unlimited visibility and clear sky. We become eager to pass this line and go lower to stay “contact” and fly under. The nose is pushed down and the airspeed goes up, so that we’re apt to start under the storm’s edge going fast. However, under this edge will be some really rough air with hard, sharp-edged gusts, and high speed will be dangerous. So patience is needed to keep us slowed to turbulence-penetration speed as we sneak under this dark shelf of storm. We should realize there’s tough flying yet to be done before our peaceful sky is won. In early airline days, a DC-3 was flown under such an area in a flat but highspeed dive by an overeager pilot. The jolts resulted in injury to 10 passengers and some wrinkles in the airplane!

Dry Climate and Thunderstorms

In dry climates, like the western United States, days with a low dewpoint and hot temperatures create very high-based cumulus clouds; assuming there is enough moisture when temperature and dewpoint meet. It is not uncommon to see cloud bases of 12,000 feet or higher, and one glorious soaring day heading north up the Rio Grande Valley toward Albuquerque, New Mexico, they were 20,000 feet. There was a bit of light snow, while a hot July day lay far below. If there is enough moisture and instability above the cloud base, we can see Cb develop. How dry it is below the cloud base will decide how much rain makes it to the ground. Dry enough, and we may see nothing but a little gossamer curtain right below cloud base called Virga, it’s evaporating precipitation. More moisture, and there are gossamer shafts of rain reaching toward the ground. This precipitation comes out inconsistent of time and location, which shows things are pretty inconsistent in that cloud. The other aspect of these storms is that they can cover a large area, spreading larger as new Cb develop. In this virga/gossamer rain stage, it’s a bad time to go underneath. Remember, we’re in dry climate, the gossamer rain might be what’s left from evaporation of serious rain. Rain means the storm has matured, with cold air headed down. This is a real setup; it’s getting ready to unleash itself, but we don’t know when or where. In soaring events, when young and foolish, we would drift under these developing thunderstorms, their lift quite good until they began to rain. With flatland soaring being convective-dependent, it was an interesting education. Let’s just say that weaving around and under these spooky shafts of rain is rolling the dice. A great example of how fast things can change happened over the flats of eastern New Mexico under a darkening line of building Cb. Seemingly okay, because nothing was coming out of them, I (ROB) was climbing nicely in good lift. Suddenly, there was a loud slap of huge raindrop splattering on the canopy, then another, but nothing continuous. At the same time, the 800 feet per minute thermal I was working turned to 800 feet per minute sink in less than a few seconds. We escaped, found lift a couple of miles to the side, then flew on, but it was a great lesson in how fast things can change; I never forgot it, and it influenced quite a few weather decisions throughout my aviation career. Decades later, my son and I (COB and ROB) were faced with the decision of crossing the Sandia Mountains east of Albuquerque in our Cessna 170. A huge thunderstorm hung over the Sandias, with clear blue over Albuquerque. We could easily see through the few gossamer rain shafts, and even thinking back, it seemed tempting to slide through. But the airplane was gutless in that high country, and memories of those soaring years’ past told us we knew better. Then my son pointed out a swath of virga, way above, white as in snow or maybe hail. Moments later a nice zap of lightning flashed a few miles away. We turned around and landed at Moriarty, then in sun, but by the time we’d tied down, the wind had swapped 180° from the storm’s falling air, bringing rain then hail. The locals said it never hailed—figures.

A great picture of a line of thunderstorms along a cold front. The “open” places between the storms are very high and will tend to close up as other cells develop. This isn’t a front to try VFR. It’s an instrument flying job with airborne radar equipment required. (PHOTO COURTESY OF NOAA) These are storms that breed microbursts, and we rarely know when they are ready to fall, even by fiddling with radar, lightning detection or dark-magic. That cold air and rain heads down from the cell, then spreads out as it hits the ground, giving us that dreaded wind shear we talked about earlier. If it’s a wet microburst, we see the rain and don’t fly into it. On the other hand, if we see dust and junk rolling up in kind of a vortex ring, it’s a dry microburst. Either one is bad news, especially, as said before, when landing or taking off. The problem is, if we are there when it happens, it’s too late. There are a few danger signals that might indicate microbursts: Wet microbursts: • • • •

Heavy rain or lightning Rain shaft Strong storm outflow (wind), blowing dust and debris Clouds with a bowl-shaped underbelly

Dry microbursts: • • • • •

Surface temperature above approximately 24 degrees C (75 degrees F) Temperature-dewpoint spread of 15–25 degrees C (30–50 degrees F) Convective, high cloud bases that may also be bowl-shaped Virga or scattered light rain Radar returns of weak cells with high bases

These are helpful criteria, but not cast in stone. They can vary, as should our thinking and creativity, in dealing with thunderstorms and related convective

issues.

Frontal Thunderstorms We visualize frontal thunderstorms as part of a dark, vicious cold front moving across the countryside with high winds, pouring rain, and much lightning, and that’s a pretty accurate picture. But there are warm front thunderstorms too, and they are different. What’s the difference? Well, it’s mostly in the height of the storm’s base. A cold front’s storm base will be close to the ground, with no room to fly under without getting the full force of the storm. But warm frontal storm bases are generally aloft. How far aloft will depend on the frontal slope. We’ve seen thunderstorm bases as high as 16,000 feet, which is unusual. But I’ve seen lots at 4,000 and 6,000 feet. Between Chicago and Kansas City, Missouri, for instance, there are often thunderstorms reported over most of the route. However, by closely examining actual weather reports, one could see that the bases were high, which indicated a warm front condition. A flight at 2,000 feet put the airplane in smooth air, although there were clouds, stratus from falling rain, lots of rain, and frightening lightning all the way.

The Surface Wind Tells How do we learn if it’s a warm front kind of condition? First, as always, is a look at the big picture. Where are the fronts and what kind are they? Next, a careful study is made of the surface weather reports, with particular attention paid to surface wind. If the storm bases are high, the surface winds will not be strong and gusty at stations reporting thunderstorms. The wind will pretty much stay normal for the general circulation. This is the best clue that the storm is a high-based one. A warm front will also have storms over a large area with extensive cloud cover. A cold front, in contrast, will show up as a line of thunderstorms and can be seen on surface weather reports by the strong ground winds and a dramatic wind shift as it passes a station. A warm front is of special interest to the turboprop and light pressurized twins, because their normal altitudes may put them near the warm front surface aloft, where the thunderstorms are wildest. The pure jet will get on top of all this, or up where it’s easy to dodge around, and the little guy will be lower and probably under the thunderstorm bases.

How to Tell a Front’s Toughness The intensity of a cold front can be learned by studying the sharpness of the wind angle ahead of and behind the front. If the wind in advance of the front, for example, is from about 210°, and the winds behind the front are from 340°, we

can bet that the front will be a wild one. Also, the larger a low pressure’s warm sector, the more violent a front. The bigger the temperature difference between the warm and cold side of the front, the tougher it will be. It is also important to check the speed of a cold front by looking back over the sequences to see how fast it has been moving. If it speeds up, you can bet it’s getting stronger. And, of course, there is our old friend orographic influence; if the front is moving up sloping terrain, that too will make it worse.

Prefrontal Squall Lines Cold fronts have a phenomenon associated with them that complicates the picture: the prefrontal line squall. This is a line of thunderstorms that breaks out 100 to 300 miles ahead of a cold front. They occur mostly in the afternoon, when heating adds to the zip of instability, along with the lifting effect of convergence in advance of the front. All this is difficult for the day-to-day pilot to analyze; simply always be suspicious of a prefrontal line squall when a cold front is on the move. This squall line ahead of the front is where the toughest thunderstorms are found. It is where most tornadoes occur. It is where most hail is found. It is a good thing to avoid! As a prefrontal squall line develops and intensifies, the cold front behind it tends to diminish and sometimes can be difficult to find on the weather sequences. As evening approaches, the prefrontal squall line will diminish, and then the real cold front will regenerate and make itself known again. What this means is that if we negotiate a prefrontal squall line, we may think we have finished with its violence, but it may turn out that 300 miles along, as night approaches and we fly toward the dark, our cold front has perked up, and we find ourselves facing another line of thunderstorms. A good rule of thumb is that prefrontal line squalls are generally not active within 150 miles of a low center, nor more than 500 miles out from the center. They show up in an area 50 to 300 miles ahead of a front and roughly parallel to it. The breaks in a prefrontal squall line are sometimes larger than in a solid cold front line, but this is a flimsy thing to depend on.

Some Rules The same rules apply to cold fronts and prefrontal line squalls: 1. Flight on instruments should not be attempted unless we are equipped with airborne radar in good working order, and with it a knowledge of how to interpret what the radar shows. A look at NEXRAD and a lightning detection system in advance will show how active the front is, and if there are any clear

places through it. 2. Low flight underneath should not be attempted, because of extreme turbulence and the possibility of heavy hail. 3. The best procedures are to fly well around the line of storms or to land and wait for it to pass. Landing isn’t too great an inconvenience. First of all, these sharp lines of weather pass fairly quickly. Second, in a year of flying, most pilots don’t encounter such conditions more than a few times. Of the total year’s time flown, those rare couple of hours sitting relaxed on the ground is well worth it.

If We Fly Through Now, of course, comes the time when, for some hard-to-imagine reason, we barge ahead determined to go through that cold front. Where should we take it on? As we’ve said before, down low isn’t good. Another place to avoid is the area where temperatures are (minus) -7 degrees C to +4 degrees C (20 degrees to 40 degrees F). Research has shown that this is the area where most lightning discharges occur. It’s also an area where carburetor ice will be at its maximum. A logical place to go through is just above the haze level, at the inversion. Here there is a minimum effect from heating, and that may be a place where the violence is a little less, and we emphasize little. We can visualize flying toward a front. The sky is hazy and visibility poor in the hot mugginess. Cumulus clouds dot the sky. To avoid them, see better, and be in smooth air, we climb above the haze level. As we climb, the temperature decreases, but just as we come up out of the haze to where the visibility is unlimited, the temperature rises. That’s the inversion. Now we can see the cumulus sticking up through the haze. We are over Ohio flying at 10,000 feet. We should be updating weather along our route, which is easy if we have data link weather, otherwise we use Flight Watch or the FSS radio contact, noting which stations have southerly or northerly winds as an indication of the front’s location. The wind velocity, the abruptness of the wind direction shift, and the temperature difference across the front are checked as well, along with the presence of thunderstorms at various stations en route. Flying farther west we note that the tops are climbing. We are at 12,000 feet and ahead is a line of cumulus from one end of the horizon to the other. That’s our front. This line of cumulus reaches very high. At first, we have hopes of topping it, but experience says we’re kidding ourselves. The line has higher places with anvil tops. These are the cells of the storms. With either type of radar, we can see them and begin to plan a route through, but hopefully we’ll be using airborne radar if we have any thoughts of picking our way through. Lightning detection would show the hottest electrical areas, and NEXRAD the layout, but with time delay

leaving unknowns. Flying without radar, if one (incredibly) does so in this day and age, we’ll make an educated guess. Close to the front there will be a towering cloud wall extending to neckstretching heights. Below will be stratus and low, boiling roll clouds. At our level, just above the haze, we’ll see some stratus and layers. The wall of the front is a solid mass, bulbous in places; its color is eerie, anything from misty white to a black yellowish-green, depending on the sun’s position in relation to the front. We study the complex picture before us and try to decide how to take it on. We don’t want to descend and try to get under that roll cloud, because the air is wildly rough right there; it is probably the roughest part of the storm. It’s tearing up in tremendous currents, as well as chopped up and inconsistent. Close to the ground, the wind over the surface adds to the thunderstorm’s normal drafts. Progressing through this roll area, we’d run into heavy rain and zero visibility. The rain might affect our airspeed, and there are also localized pressure changes that will affect the altimeter’s accuracy. (No one can tell you how much for certain, but some knowledgeable researchers think it may be as much as 1,000 feet.) So let’s forget low down as a place to go through. We look up, way up. We’ve probably studied this area for a long time as we approached the front. What we are looking for is the lowest point in the top of the long line of clouds, a saddle between towering Cb. When we find it, our first tendency is to climb right up there and slide over between the Cb. But as we’ve said, this is risky business, because just as we are approaching the saddle, the clouds will build up in front of us and suddenly there isn’t any saddle or it’s much higher than it looks. The risk, to repeat, is that we’ll find ourselves struggling up high, at a mushing, high angle of attack ready for a stall. Unless we can zip over this saddle between the Cb with good speed and control, we shouldn’t fool with it.

At Night Finding the right place at night is more difficult, but the flashes from lightning help. Approaching the storm area, we study the cloud structure in the briefly lit periods as flashes occur. We can often spot the individual storms by the concentrations of lightning. It is well to do this from as far away from the cloud mass as possible, because close in, the origin of the lightning becomes confused as it reflects and lights up all the clouds. Lightning can be seen from a long way off at night, and storms that may seem on top of you can still be 50 or 100 miles away. Close to the storm area, when looking out, care must be taken that a nearby lightning stroke doesn’t temporarily blind you. When you’re that close in, it’s time to have the cockpit lights up bright and the decision made as to where to penetrate the mess.

Where to Bore In

We’ve decided that we cannot top the line anywhere. So we’ve picked a point under the lowest place in the top of the line confronting us. We’re above the haze level and eye-to-eye with the solar plexus of the storm. Before barging in, we ought to study the color of the precipitation ahead. If it’s white and fuzzy, with a gossamer look, it may be hail. If so, then we’d better wander up and down the line some more and find another spot that looks darker, like rain, and not whitish, like hail. Let us restate, before going into this line of thunderstorms: WE DON’T RECOMMEND IT . However, we have our spot picked and are about to go in. Now the problem changes from weather judgment to flying technique.

How to Fly It First, we prepare the airplane. We pull down on the safety belt and put on the shoulder harness. We make certain that loose items are fastened down and passengers well strapped in. Put on heat for the pitot, carburetor, or jet inlets. Now, establish the airplane’s best rough-air penetration speed and note what the power settings are for that speed and where the stabilizer trim is set. Note the airplane’s heading. However, we should pause here and talk a little about the penetration speed. Basically it’s the slowest speed possible without danger of stalling. We want it slow, so that the airplane will be in its best condition to take heavy gust loads. Too slow, however, has proven to be almost more dangerous than too fast. As we’ve said before, when airplanes come apart in severe turbulence, the problem begins with loss of control, and an easy way to lose control is to stall or to get a wing down and into a spiral dive. Clean, swept-wing airplanes are worse in this respect than slower, straightwing airplanes. If they lose control, they gain speed quickly. A swept-wing airplane isn’t as straightforward in its elevator-control system as a conventional airplane, because the amount of elevator control available is dependent on the stabilizer setting. On certain jets, pitch trim moves the whole horizontal stabilizer, and one runs out of elevator control unless the stabilizer setting is correct. In effect, because of the large surface area, the stabilizer is the elevator, and the elevator is like a trim tab. A more conventional airplane doesn’t run out of control, because the horizontal stabilizer is fixed, and the trim is what we find on, say, a Cessna 172—the little trim tab “flying” the elevator. It just gets harder to pull or push. It’s best not to fly too slowly with any airplane. Most aircraft manuals recommend the proper speed for turbulence, and it will be something like 60 percent above stall. A 100-mile-per-hour stalling airplane may have a rough airspeed of 160 IAS. Jets may have higher speeds, but again, it’s best to consult the airplane manual. Know your airplane’s best turbulence penetration speed; get

it from the manual. The airspeed we’ve picked is important, but equally important is how we fly it. What we do not want to do is chase speed with the elevator control and the airspeed indicator. The key to rough-air flying is to maintain a level attitude and do it by flying the artificial horizon. Note where level position on the horizon bar is with the airplane stabilized. Then keep it there. We do this with gentle pressures and not big pushes and heaves. Airspeed will vary, often wildly, and if we attempt to chase it by pushing or pulling, we’ll soon get into some pretty extreme attitudes. The trim and power settings should not be moved to any large degree. The proper pitch attitude, power setting, and stabilizer position are important to know in advance, so one can set these up quickly and not fight an out-of-trim airplane while trying to settle down to the proper airspeed and power setting. These settings should be learned, as we’ve said, on a clear day, by trying them for various altitudes and weight conditions. But the best insurance is to get down to turbulence-penetration speed, power setting, trim, and attitude before one enters a turbulent area. Of course, there are times when we hit turbulence unexpectedly; that’s why the clear-air experimentation is useful to give us guidelines to shoot for when things are suddenly wild! We have to face the fact that it is difficult, often impossible, and generally undesirable to maintain a given altitude when flying through the business part of a thunderstorm, ATC or no. Of course, we try to maintain the proper altitude, but only as long as it doesn’t require appreciable power or attitude changes. Too diligent an attempt to maintain altitude will result in the extreme attitudes and/or power changes that lead down the path to loss of control.

Are We Scared? A thunderstorm line is a pretty awesome sight. It’s scary, and any honest pilot, no matter how experienced, will tell you so. This fear is a factor to consider. We’ve mentioned that, scared or not, a weather-flying pilot has to control emotions and keep imagination subdued or use it only to advantage. The pilot has to fly carefully and thoughtfully, even though scared to a knee-knocking state. The toughest place to keep this fear under control is in a thunderstorm. It is dark, it is turbulent, rain comes down in a deluge, lightning flashes close, sometimes we can hear thunder, and occasionally we smell ozone from a nearby lightning passage. A lightning discharge may make a brilliant flash and loud bang. An irritating, hashy noise may be tearing at our eardrums from static in the radio. It’s a hell of a place for anyone to be! It takes a strong will to say, “I’ll watch the horizon and keep it level. I’ll hold that heading, keep the wings level, and it will all turn out okay.” But that’s it, and the only way to do it. To help our situation, we should have the cockpit lights turned up full bright. If a lightning strike occurs, this will prevent temporary blindness. We should drop

the seat as low as possible and keep our eyes inside the cockpit for the same reason. Bright lights and a low eye level help protect from a blinding flash, and they help psychologically, too. The bright cockpit lights keep us from seeing out, as does the lowered seat, and this helps shut out the terror. It puts a “protective” barrier between us and that awful world out there. It’s a phony barrier, to be sure, but if it helps subdue panic, who cares? So we come closer to the actual clouds. The first thing that makes us feel something’s about to happen will be a strong updraft. It probably will be smooth but powerful. The airplane wants to go up, and if we push ahead to maintain altitude, the airspeed will also go up. We can pull power to keep the speed low, but then the engines may cool so there won’t be enough heat for carburetor or jet inlet anti-icing. If we don’t pull power, then we get a nose-high attitude that’s undesirable. We are probably best off leaving the power set at our best rough airspeed setting, keeping the horizon on the position of pitch for level flight, and the devil with altitude. If we are using an autopilot, the altitude hold may want to be off and the airspeed hold, if there is one, should definitely be off. The human pilot should keep the nose on the horizon bar with the manual control. The autopilot will only be doing the heading and lateral work, which is a help and important, but it is stupid in its handling of altitude–attitude–airspeed relationships. (Older autopilots were more of a problem in the altitude hold situation, but newer ones can be much better. Auto throttles can cause excessive pitch changes, especially with engines mounted on the wings, so it may be best to deactivate them as well. However, we want to consult the aircraft manual on the recommended autopilot/ turbulence procedures, as well as try it on a turbulent, VFR day. This knowledge may be important in many turbulence situations.) Whether we’re on autopilot or hand-flying, the wings should be held as level as possible, even if it takes big aileron movements and a lot of work. Nonlevel wings hurt speed control, because an airplane wants to descend when it’s banked, and level wings help to keep us going straight. The last thing we want to do in a thunderstorm is wander. We start in with a heading that we feel is the shortest way through, and then hold it tight to quickly get through. The biggest updrafts occur outside the cloud. Rain hasn’t started, but we don’t like the feel of the updraft, because we know that when it stops, there’s going to be a jolt. Then, just as we start into the cloud, our updraft stops with a jolt, and the air becomes very turbulent. Side gusts, downdrafts, updrafts … it’s wild. It’s dark, and as the airplane is jolted and jarred, heaved up and squashed down, the rain begins with slaps of big drops at first, then, suddenly, inundation. The rain flows over the windshield like a river, and it is noisy. Most people would say it is hail. There may be soft hail, and it may make a frightening noise, but it isn’t big, solid hail. Solid hail is a noise to end all noises. It’s unforgettable, tremendous, and no one ever mistakes it for heavy rain once they’ve heard it. And what if it is hail? There isn’t much to do. Keep a firmer grip on emotions,

but above all hold the heading! Hail is confined to a small area. Turning back will probably result in a longer time in the hail. Also, a turn will expose the side of the airplane and break out windows. In years past, when even large aircraft had fabric-covered control surfaces, the amount of up-elevator needed for the turn may have exposed enough fabric to tear it open. I (RNB) saw a DC-3 once that had flown into heavy hail in Kansas, and the pilot had turned around. I looked at the airplane as it sat in the hangar, a battlescarred wreck. The leading edges were beaten in, the landing lights broken out, and the windshield, too. But most interesting was that every window on one side was broken! Fortunately, it was a cargo flight without passengers. The fabriccovered elevators had numerous rips and slashes. So don’t turn around in hail. There are some interesting points about hail. Most of it in the United States occurs between the Mississippi River and the Continental Divide. April, May, and June are the worst months, and the worst time of day is between 2 p.m. and 10 p.m. Cold front and prefrontal thunderstorms are more apt to have hail than airmass thunderstorms. Hail forms in the storm’s building stage and falls when it’s in the mature stage. It is largest near the freezing level. Flight well above or well below the zerodegree C point decreases the risk. Looking again at the tropopause and thunderstorm heights will give a clue to the possibility of hail. If the radar reported storm tops pushing up above the trop by 5,000 feet, one can expect to find at least ½-inch hail. In the black, heavy rain, the turbulence keeps up, but there is a feeling that it is diminishing. It’s still wild and rough, but we feel more in control of the situation. There was probably a point in the early part when it was so rough that we doubted our ability to keep control if it got any worse. Now, in heavy rain, we feel that the out-of-control threshold has been lowered in our favor. The rain does dampen the turbulence to some degree.

Something to Be Said for Rain There was a time, before radar, when pilots said that if you must go through a thunderstorm, pick the blackest part with the most rain. When radar arrived, this became taboo, and we learned the error. The reason, of course, is that radar shows where a cell is by reflecting from the rain. So radar says, “There’s the heavy rain, that’s the storm’s cell. Avoid it!” This is essentially correct. But the most severe turbulence isn’t exactly in the middle of the rain. It’s close by, however, and if you miss the rain area by a good margin, you’ll probably miss the worst of the turbulence. Don’t be sold on the idea that the center of the rain is the wildest part of the storm, although it may have the most violent downdrafts or microbursts as they are called today. The roughest place is probably in the area just ahead of the

storm, near the roll clouds, before you go on instruments.

Fly! Now, back to the storm. Our job is a simple one, really: just fly the airplane. Fly attitude; keep it level and under control. We need a certain attention to the engines to make certain the carburetor heat is sufficient and that they are not icing. With injected piston engines, we’ll be considering alternate air sources. There’s little navigation to do. We can glance at our course and try to stay with it or consider radar deviations, but realistically, we shouldn’t do any excessive squirming, especially with large bank angles. It isn’t going to be far enough through the roughest part to make much of a difference.

Electrical Discharge Lightning will flash in this darkness, and some of it seems close. The sky is lit up for moments, and its brightness is scary. Between flashes, when it’s dark, we can see small flicks of fire-like miniature lightning dance across the windshield, and a quick peek at the propellers, if we have them, shows a neon-like band circling their tips. This is Saint Elmo’s fire, more formally called corona discharge. It means that the airplane has been flying through electrical fields, absorbed energy, and is charged. If it collects enough charge and passes through an area in the storm that has a big charge of opposite polarity, the energy may jump between airplane and cloud in a type of lightning. It goes off with a loud banging plop and a brilliant flash of light. If you were looking out you’d be temporarily blinded, but looking in or out, it will scare you. It’s over in a second, and we are surprised to note that the airplane still flies, and the wings haven’t fallen off. If we could see the damage, we’d probably find a half-dollar-sized hole near the wingtip or at the tail cone or in some other smallradius area. The side of the fuselage might have very tiny, rough, bubbly imperfections, as though it was partially melted; it was! A radio may have been damaged, and we should look with suspicion at the magnetic compass. In some aircraft a generator/alternator may have fallen off-line, so that may need resetting; usually it comes back. What happens to electronic displays is potentially varied, but usually they are fine. However, this is a great example of when the glasscockpit and autopilot-dependent pilot may quickly need to hand-fly raw data from a small standby horizon or, hopefully not, a turn coordinator; if this happens in all the turbulence, we don’t have time to fiddle and troubleshoot, instead we just fly until we’re out and all calms down. Beyond this we are okay. Thousands of these discharges have occurred with few serious results, except as noted in the beginning of this chapter. These are commonly called lightning strikes. They are the only kind an

airplane gets. Airplanes aren’t “hit” by lightning as we visualize a person on the ground being hit. There is always an electrical discharge between airplane and cloud. A person on the ground, actually, isn’t really “hit” either, but is a point where electrical potential jumps from earth to cloud through the person. Though we always think of being “struck by lightning,” the person “struck” is a part of the process of discharge. The chances of a discharge can be lessened, as we said, by staying out of a temperature region that is 4° degrees C either side of freezing. The majority of discharges happen where the precipitation is rain mixed with wet snow. There are little tricks, too, that may help; they certainly will not do any harm. One is to turn on propeller alcohol/deicing fluid, if available; another is to flick the mike button now and then. What these two things may do is help carry away part of the energy that’s been built up on the airplane. It’s a slim possibility, but may be just enough to keep the charge below the critical point. The important thing, however, is to stay away from the freezing-temperature area. Incidentally, the faster the airplane, the more likely we will get a discharge. Also, while keeping away from the freezing level is best, it’s not a guarantee. The discharge I (RNB) had out of London, resulting in that big piece being torn out of the 707 radome, occurred between two cumulus whose tops were only 11,000 feet at a temperature of 14 degrees C. The electrical charges come in two ways, and they are worth talking about. One we have explained: accumulation of charge caused by flying through electrical fields. These are huge, with tremendous voltages, and are part of the thunderstorm instability process. I always visualize thunderstorms as big waterfalls of electrical energy; you fly through them, and the airplane is covered by the energy, of which a great quantity is absorbed. The other kind of charge arises from flying through precipitation. This, crudely, is a friction process, like the crackling one hears when combing one’s hair with a plastic comb on a dry day. This type of charging doesn’t affect things nearly as much as the field type. It’s easy to see that when flying through a thunderstorm we get the field-type charge, and if we are flying in the wet snow area, we also get the friction type in its worst form, so we are getting the maximum. Getting away from wet snow deducts part of the charge—unfortunately the smaller part.

Static and Radio All this charging causes static, which knocks out radio reception on certain frequencies. Fortunately, it rarely affects reception in the VHF ranges. It offends most seriously in High Frequency (HF ) frequencies used in long-range communications, as well as the ADF 200–400 kilohertz range, for those who still have ADFs. An electrical charge looks for the easiest way off the airplane. This will be any

small area, like a copper antenna wire. Of course, when the charge bleeds off an antenna, it makes a terrible noise in the radio. Although long-wire antennas are pretty much things of the past, the solution was to use a large wire with a polyethylene coating, the entire thing being about the diameter of a pencil. Also, the insulators and attachment hardware are large and smooth so that no wire end sticks out in the air. The big wire and smooth insulators discourage discharge, but this was impractical for smaller aircraft and, as said, are today more of historical fact than use. The other part of antistatic hardware is the little wicks we see sticking out from the wing, stabilizer, the rudder, and sometimes, the tail cone. Today, some are less similar to wicks and more like little prongs. These are designed as a place where the charge can bleed off quietly and easily. All this helps, but only for the “friction” type of charging; it doesn’t impress the electrical-field type of charge at all, because the charge is so big the wicks cannot bleed it off, nor could large-diameter wire antennas when they were in vogue. If they could, we’d never have a big-bang discharge. This was a major problem in the low-frequency, radio-range, and HF days. The issue is now much less of a problem because of VHF, but electrical fields are so strong, at times even VHF will start to howl and squeal in thunderstorm conditions. It generally doesn’t last long, but when you hear it, a discharge may occur. For long-range airplanes needing HF for communication, precipitation static discharge can be a problem. The ADF is becoming somewhat extinct, but where it is still used, we need to remember it will be knocked out by precipitation static, with ADF bearings becoming unreliable. Following an ADF indication could easily take one off course and perhaps set up a dangerous situation, particularly in mountainous areas. We should look at all ADF bearings with much suspicion when flying with excessive static.

The Noise Is Annoying While we are tossing around in the dark, wet, and rough inside a storm, we can use radio noise in a couple of ways. If we have HF frequencies, or are using low frequencies, the noise will be so continuous and loud that nothing else will be heard. At that point, all the radio is doing is aggravating our condition of apprehension. The best thing to do is to turn it off. It’s surprising how calm things become, even in the turbulence, to suddenly have that infernal noise go away. If we are using VHF, we leave it on. The occasional squeaking noise we hear may tell us a discharge is close. While at this point we cannot do much about it, it will at least have us prepared and not so startled when the bang and flash occur. Squinting, clenching your teeth, and pressing the mic button are about all you can do.

Almost through the Storm As we continue, the rain slackens, the turbulence quiets down, and patches of lightness bring encouragement. We may fly out of the storm quite quickly and dramatically, finding ourselves in brilliant sunshine. While we breathe a sigh of relief, it’s a good idea to remain fastened down and alert until well away from the area. We have traversed this storm from front to back. The worst part was first, because the roughest part is the front, or leading part, of a storm. Had we been coming the other way, the sequence would be reversed. The rain would begin, and turbulence would start; it would become darker and darker, and the rain and turbulence would become heavier. Toward the front side, light spots would appear, but it is then that we’d get the real rough stuff, that wild updraft and turbulence even after we have broken out of the clouds. Flying back to front, we want to be well through and ahead of the front before we relax. Now, suppose we are flying a jet and hit all this up high, at 25,000 or 30,000 feet. What’s up there? Lots of snow, for one thing, and turbulence, probably not as rough as down lower, but still very rough. There is more chance for hail, and electrical discharge—lightning—is quite possible. The massive amounts of snow, some of it in the form of very large flakes, may cause icing, especially inside warmer intakes, where the snow is melted only to refreeze later in a colder area. In jets, we might inadvertently clip thunderstorms if we have been flying in cirrus cloud, which sometimes is from thunderstorm blow-off. Yes, we are not supposed to do that, but if, for example, we are crossing the Rocky Mountains on a later summer day, there can be thunderstorms and blow-off just about everywhere. With no rain up high, we have to tilt our airborne radar down low, at the same time trying to find storms by shadows on the radar screen displayed behind the storms, as ground clutter in mountains makes things difficult. NEXRAD gives us good idea, but not without figuring delay and possible terrain issues. Lightning detection, if onboard, may be our indication. The best deal is keep glancing outside, looking for the bulges of tops through breaks in the cirrus. Eventually we’ll nick something, but unless we are hanging on up too high, it’s a brief period of pretty good bouncing around, and that’s it. In these conditions, it’s a good idea to have everyone seated with their belts on; maybe the engine anti-ice on too, all just in case. By the way, turning engine anti-ice on will reduce our power, and hence our altitude capability. While doing thunderstorm research, I (RNB) barged into one at 35,000 feet in a B-17. It was impressively rough, but most impressive was the size of the precipitation. The snow looked like big snowballs being thrown at us. This stuff got into the intakes, clogged them up, and, by restricting the airflow, caused supercharger ducts to squeeze in. The result was four very weak and helpless engines and a big, not-so-good glider! Fortunately, the high altitude made it

possible to glide away from the storm, get lower, and reorganize things so that we could limp to an airport. Up high or down low, a thunderstorm is potent. Even over the top of one, as mentioned earlier, turbulence will extend upward into the clear air a few thousand feet.

Warm Front Thunderstorms When flying warm fronts, we will be on instruments most of the time, and it will be difficult to see individual storms. Occasionally, the airplane will break out between layers, and then it may be possible to see the Cb towering up from the bottom layer into the higher layer. Because we cannot tell, without radar, where the storms are in a warm front, we should be prepared to fly into a thunderstorm at any time. And while they may seem a little less violent, they are still thunderstorms and can be as rough as any.

Low Down The best rule, in warm front conditions, is to fly low. Keep down, near the minimum instrument altitude. Because we are dealing with turbulence, it’s best not to fly too low, and we personally prefer 2,000 feet above minimum instrument altitude. This is dependent on terrain. If it’s all flat, we’d feel secure 2,000 feet above the ground, but in mountainous areas, we want more. This low flying in warm front thunderstorms is due to the fact that warm front thunderstorms generally have high bases. The air has to crawl up the warm front to have enough lifting to set off the thunderstorm. If we are flying a jet, we don’t fly at 2,000 or 4,000, although I’ve known of this being done with considerable success—if fuel isn’t a problem. With its highaltitude capability, a jet will sometimes top an entire warm front—over the ocean, most certainly. But if a warm front with thunderstorms cannot be topped, then it’s best to come down to an altitude where the airplane is flying well and to use airborne radar for sneaking through it. The best altitude will depend on the jet’s performance; generally speaking, about 33,000 feet is good. At high altitude, the storms seem more widely spaced and easier to weave through. If you’re in a highflying corporate jet, you may just be above it all. Have a nice day.

Thunderstorms as We Arrive and Land Sometimes we are faced with the problem of our destination being covered by a thunderstorm or having them so close that they affect our landing. What do we do? First, we must approach the area and dodge any cells near the airport. We can do this by VFR procedures if we can see, or preferably by airborne radar. The

complication, of course, is ATC. If we wander around dodging storms, we have to keep ATC advised and get their approval prior to commencing our weaving around the weather. It’s only logical that two airplanes from opposite directions might be headed for the same good area. A deviation might also put us on another airway or arrival route, which will then put restriction on how far ATC might let us deviate. ATC will sometimes help lead one through a thunderstorm area. This can be a mixed blessing, but as mentioned earlier, ATC’s weather radar abilities have improved. We recall that ATC’s primary job is to separate aircraft, so if they are busy, they may not have time to help as much as they’d like. The best plan is to ask the controller, before entering an area where we may need weather avoidance, if they have time to assist us. If not, then we need to decide if we can adequately and prudently do this ourselves, whether visually or with whatever thunderstorm avoidance devices we have: airborne radar, NEXRAD and/or lightning detection. Again, if the thunderstorm situation is no worse than a few isolated cells, we might consider continuing. The best would be that arrangement of airborne radar supplemented with NEXRAD and/or a lightning detection system. If at any time on the arrival we risk losing path to escape the weather area, we had best consider turning around right then. Otherwise, there is a good chance we may have to fly through a thunderstorm! Suppose we made all the conservative decisions, but still got stuck in a tight avoidance situation with a lightning detection system or NEXRAD. We have to remember limitations of no precipitation indication (heavy rain, micro-bursts, hail) if only using lightning detection, or the time delay issue with NEXRAD; base or composite scan knowledge can be helpful as to the cell potential. If we have airborne radar, we should be competent in using it to the fullest, otherwise it might make things worse. And what if we have nothing to help us? Well, hopefully ATC can help out, otherwise we are walking blindfold in a forest. If we are dealing with frontal, squall line, or severe weather, we shouldn’t be there anyway, and hopefully we have kept open an avenue for breaking off the arrival and going somewhere else. Lastly, all this deviating as we approach an airport is one thing, but when we get there and the airport is under or near raining Cb, or under ones that look just about ready to let loose, hopefully we have not cornered ourselves in the weather so we can’t land or escape the area. We need to be the judge—and boss!

Don’t Race Thunderstorms A real hazard is a pilot trying to beat a thunderstorm to the airport. There’s nothing wrong with trying to get there first, but there are a couple of possible pitfalls. One is diving and allowing the airspeed to get too high, and then suddenly flying into the rough area just ahead of the storm at this high speed. Another is

racing to get to the field and then landing as the storm arrives, or even when it’s 5 or 10 miles from the airport. The wind shifts abruptly with gusty force, and a cross-tailwind suddenly makes landing difficult, perhaps impossible. This, again, is where severe shear occurs. With the wind shift comes heavy rain that obstructs all vision, and one may suddenly go completely on instruments—zero-zero—anywhere along the approach. At 100 feet, for example, the pilot will suddenly be unable to see the ground. Even if the rain arrives just at touchdown, the visibility will be so poor that it will take luck to make a straight runout and stay on the runway. It’s a terrific shock to suddenly learn how bad visibility is in heavy rain. Braking will be poor, possibly nil, on the wet runway. The airplane can hydroplane and not stop. With a strong crosswind, it can also slide off the runway sideways. And always remember that thunderstorms on or near airports are the classic recipe for shear accidents. Maybe a fair rule of thumb: if we have to either land in, risk landing in, or pass through on approach any heavy rain areas, especially when we are unable to see through it, we should discontinue the approach or landing, stay out of the weather, and go somewhere else.

Missed Approach In Thunderstorms Now, an important point. Let’s say we are racing a line of thunderstorms to an airport. The line arrives just as we do. We decided to pull up and abort the landing, because it is impossible. Now, which way shall we turn, right or left? In the northern hemisphere it’s best to turn right. Why? The wind has probably changed to northwest. Making a left turn, we will have a momentary drop in airspeed, bringing us closer to stall; the sudden, new, side component of wind will also tend to overbank the airplane; an intense downdraft will be present as the cold air arrives. It all spells an airspeed loss that’s difficult to regain. There have been accidents that were caused by loss of control when turning away from a thunderstorm. Of course, if you are still in the southerly wind part of the approaching storm, you’d best turn left. The point we are trying to make is that if you get in close to a storm, particularly where the rain has started and the wind has shifted, then decide to turn around and get out, it is best to make a right turn. Another variation worth watching is an isolated cell near an airport, yet to rain. The wind very likely will favor going toward the cell; it is being sucked in. However, when the rain begins, it will spread out as it hits the ground, just like a microburst, even if not a classic, full-fledged one, with the wind now rushing away from the storm, totally opposite from before the rain. In smaller sense, a good soaring sky full of fair weather cu is susceptible to this same event, usually of smaller magnitude, but nevertheless worthy of

mention, as a wind swap may affect our aircraft’s performance. That’s why it is important to look not only at the windsock, but the sky as well. There isn’t always time or circumstances to do the correct thing, but right or left, remember the air will be gusty and shifty, and it’s very important to maintain enough airspeed above stall to take care of downdrafts and wind shears. If power is needed to accelerate the airplane, this isn’t a time to be bashful about the amount. Pour it on, lots of it. It takes an airplane longer than you think to gain airspeed by power alone when pulling out of a low-airspeed condition.

After the Missed Approach and Other Thoughts When we have hopefully made that missed approach and are away from the storm, what then? If it’s an air-mass storm, we may want to hold out in a clear area until it leaves our airport, and then go in and land. If it’s a front, we’ll have to pass through it before we can get to our airport. This case calls for a retreat to some still-clear airport where we can land and wait until the front has passed. Then we fire up and complete the flight calmly and pleasantly. Let’s say we have put ourselves in a pickle, either on this missed approach or flying anywhere around a thunderstorm area, and find ourselves boxed in, unable to escape getting into the storms. If we’re flying a light aircraft, and especially without the capability to fly in such conditions, it maybe time to swallow our pride and consider an off-airport landing, just as was mentioned in the VFR chapter. In hopes we have given ourselves time, we look over our landing spot, plan the approach, and methodically fly to landing. Even if we ding our bird, it’s better than losing it in a thunderstorm. Once you get on the ground, no matter where you are, give careful consideration to running around the airport in the middle of a thunderstorm. Years ago, two aspiring, aviation-loving young fellows ran to tie down an aircraft in a thunderstorm. They were struck and killed by lightning. Aircraft are expensive, but hardly worth that much. In summary, the first thing in any airplane at any time is to stay out of thunderstorms! If you must fly through fronts or heavy cloud cover that contains hidden thunderstorms, don’t do it without radar and/or a lightning detection system. If the radar fails while you’re in the middle of the mess, or for some other reason you get caught, fly the best speed, fly attitude, and hold a heading. Remember power settings and stabilizer settings, so if excessive dives, climbs, or upsets occur, you’ll know where things ought to be for the best chance of flying through the situation. Don’t fly very low or very high! And most importantly, keep emotions under control—fly smoothly and coolly.

16 Ice and Flying It What’s it like when an airplane picks up ice? It begins by forming on little corners of the windshield, and on the wing we see a polished look at the leading edge, if it’s clear ice, or a fine line of white, if it’s rime. If the windshield isn’t heated, a smear of ice will cover it. Ice will begin to accumulate on pieces of the cowling, antenna masts that stick out, and other un-deiced places. When icing conditions are possible, and before getting into ice, an aware pilot knows what the indicated airspeed (IAS) should be and the right power settings for it, whether we’re flying a propeller or jet airplane. Then, once in ice, these settings are observed carefully for any changes. Change in IAS is a sure way to know the ice is affecting the aircraft, and power changes say engine heat had better be applied quickly. However, the all-important point is that at this early stage of ice accumulation —right now—a pilot should work to get out of the condition! Don’t cruise along hoping for better or grind around in a holding pattern. Let ATC know immediately that you want out. Get a different altitude. Go down if there are above-freezing temperatures below. Get on top if you know where the tops are. Be careful about climbing, however, if we don’t know what’s up there. If it’s a warm front condition, we can climb into worse conditions and climbing along the slope of a warm front is really asking for a load of ice. As a rough rule, we climb in a cold front and descend in a warm front, but this is variable. Each weather condition should be analyzed and studied by the pilot before deciding what to do. Unfortunately, we cannot make hard-and-fast rules about each weather condition. We know things in a general sense, but have to look at the flight as an entity, with all the parts that may affect the outcome: preflight weather study, fuel remaining, terrain below, availability of places to land—the entire jigsaw puzzle of flight, with each part influencing the decision of what to do. Fortunately, fronts take up a relatively small portion of our weather time. The lesser weather, such as air-mass conditions, makes up most of it. We can come closer to rules for flying in these conditions, and they are covered in various places in this book. Let’s imagine we got into ice and didn’t do anything about it, but instead just sat there and let it grow. We would begin to see an airspeed drop. This is always a little alarming. A couple of knots doesn’t impress us much. Five knots begins to, and when ten knots have gone we get edgy. The thing to do is pour on more power. We want to keep the airplane at as low

an angle of attack as possible. We don’t want to get in a tail-draggy situation, with higher drag and ice forming back under the wing. If we do not see much or any ice on the wings and can see our stabilizer leading edge, it may already have a nice buildup. That’s because the aerodynamics of surfaces that are thinner, and have a sharper leading edge, build ice earlier and quicker. Beyond our tail, think antennas, streamlined landing gear legs, and propellers, too. About the time our airspeed loss is bothering us, we develop a bad vibration. It is a hunk of ice breaking loose from the propeller. We check to make sure the propeller heat or fluid is functioning properly. If our airplane has fluid anti-ice with a variable flow, we’d want it on the highest rate. Now another vibration begins. The unheated windshield gets a thicker coating, and we can’t see ahead at all. On the corner of the windshield a big hunk of ice has built straight ahead into the airstream, and it’s four to six inches thick! The vibration gets worse, and now a howling starts. The howling is probably an antenna mast vibrating from ice, disturbing the airflow around it. The wing is going to have a good coating, so hopefully the airplane has a deice or anti-ice system, which should be in operation. With deice boots, we have them working as recommended for our aircraft; some systems use manual actuation, while others apply multiple actuation through timed sequences. The ice may break off in chunks, leaving pieces that sit in the airstream and go up and down with the boots. We watch the leading edge, hoping the chunks go away with further actuations. A fluid anti-ice system should be weeping over the wing at the maximum level needed to remove the ice we have. A heated leading-edge surface system should be on and hot. The engine cowls of a propeller aircraft now have a large coating of ice on their leading edges. The scoops have ice around their openings. The propellers periodically heave off hunks of ice and the vibration increases. The antenna mast howls and shakes. With boots, the removal may not be so efficient, and the wing can have more ice, so we try the boots again, or if we have a good automatic system let it keep the boots pulsating. An anti-ice system of fluid or hot wing should have things cleaner, but if the ice becomes severe, we are reaching the limits of a certified system. Boots may see hunks break off, but some hunks don’t, and there’s a messy collection of ice pieces behind the boots. The airspeed has dropped more, and we apply more power, resetting the carburetor heat as we do. The throttle is open an alarming amount. The ice on the engine cowls is almost out to the props. The vibrating and howling from masts is eerie, and then it suddenly stops. So does one of our radios. The antenna mast has been carried away.

A radio mast, about 12 inches high, loaded with drag-causing ice. Where some antennas can be deiced, not all are, like this one. The more of these “ice catchers” on an airplane, the less time one can stay in ice—ice-protected or not. (NOAA PHOTO) The wing boots are only doing a partial job, and bigger hunks of ice go up and down with the boots. The airspeed continues to decrease, and the throttle is wide open. The only way we can maintain speed is by losing altitude. The only way out of this mess is down, and we hope there are above-freezing temperatures down there, before we get to the ground. The situation is pretty desperate, but was unnecessary, if we had done something about getting out of the ice when that little bit first formed on the windshield corner. Ice affects the flying qualities and characteristics of an airplane. The most serious thing it does is destroy smooth flow and make a different airplane of the

one we know. The weight of ice is of secondary importance. Ice affects the wing section. It affects the propeller in the same fashion. It collects on things sticking out that create parasite drag like antennas, wires, landing gears, and cowlings, which creates more drag. Even with relatively clean, deiced or anti-iced flying surfaces and propellers, if enough stuff sticking out that isn’t clean, it turns into an anchor. Drag of these unprotected areas can increase certain aircrafts’ total drag over 30 percent. Ice will also cause an object like an antenna mast to vibrate and howl severely and finally to break off, or half off, which may be worse. The first experience I (RNB) ever had with ice was in the early 1930s, flying my Pitcairn Mailwing biplane. Cockily, with a newly learned ability to fly instruments, I barged into a large midwinter cu. In a few moments, I had an appreciable load of ice. It collected on the wires that held the wings on. The wires started to vibrate wildly up and down at least a foot each way. I expected them to break at any instant. I didn’t have a parachute. I quickly flew out of the cu, the ice shook off, and the wires didn’t break. I had become much older and wiser. My next serious ice experience was in the early 1950s during the heyday of the big piston-engine airliners, which involved flying a Lockheed Constellation across the North Atlantic. At 18,000 feet, I encountered light ice, which covered a long, thick wire antenna that went from a mast up front to one of the three fins at the tail. The antenna vibrated and finally broke near the fin. The long wire, with a big antistatic insulator on the end, whipped around and kept beating against the fuselage. I tried different airspeeds in the hope that the wire would “fly” out straight and stop beating the fuselage. Nothing helped and finally the insulator gave a sound whack to a window, breaking the outer pane; fortunately there were two panes. But this meant reducing the cabin pressure and descending. The descent took us into a worse icing condition. It was a moment of relief when we finally landed at Gander, Newfoundland. The point is that often the gadgets on the airplane are the worst offenders. If a pilot expects to fly a lot of weather, the airplane should be as clean as possible, with a minimum amount of stuff sticking out. Flying a 747 or any jet leaves little ice and none of the howling, vibrating stuff from gadgets that collect ice. The jets are “clean” airplanes and the “cleanness” reflects in their resistance to icing. There’s also a temperature rise over a jet’s surfaces, due to ram air at their high speed, but that’s another story, and certainly not an issue for our general aviation operations down low and in the weather. However, jets have to land and takeoff just like every airplane, and in severe icing, a jet operation still needs to be concerned, despite their efficient heated anti-icing systems. Most important is that no matter what we are flying, we must realize that deicing or anti-icing equipment does not allow us to fly indefinitely in ice. It cannot do this job for all conditions. It will help and give us time to work out of

icing situations, but it will not allow us to sit there all day long. There are a lot of reasons why it isn’t good enough, and one of the main ones is that deicing equipment doesn’t cover the entire airplane. Another is that it doesn’t completely clean off all the ice. So we have an important first rule: When ice is encountered, immediately start working to get out of it. Generally this means a different altitude, after a request to ATC. Unless the condition is freezing rain, it rarely requires fast action, and certainly never panic action, but it does call for immediate, positive action.

About Ice Now let’s talk about ice in detail. First, there are officially three kinds: clear, rime, and mixed, but the latter is a combination of the primary two: clear and rime. They are what they sound like. Clear ice is a smooth, hugging type that is tough. Rime is crystal-like and pretty. When it forms in windshield corners or other places where airflow patterns change, it takes on weird shapes and sometimes sticks out ahead as long cones into the airstream. Rime ice breaks off fairly easily with deicer boots that pump up and down. Anti-ice systems of heat or fluid should be actuated when we expect ice or when it initially begins, theoretically keeping it from building up in the first place. Clear ice doesn’t always break off with boots, and one difference between rime and clear is that clear ice cannot be as easily removed by deicer boots as rime can. This is an oversimplification, however, as other problems can develop on unprotected surfaces, which we’ll talk about further in the chapter. Ice comes in four classes: trace, light, moderate, and severe. These are difficult classifications that depend on the pilot’s judgment; one person may think a certain degree of icing is light, while another calls it severe. Even aircraft that are FAAcertified for “Flight Into Known Icing Conditions” (FIKI) reach a point where the system can’t defeat the ice. That starts at the severe category, but again, it is not easy to determine what sort of ice we’re in. If our aircraft is not FIKI-approved, our plan should be to depart into conditions where we can stay out of ice. Modern forecasting is getting better, but still the sky is full of changing pockets and altitude levels of various moisture and temperature variations, making total forecasting accuracy impossible. Consequently, in a sky with potential ice ingredients, we have to assume it will happen, despite what a forecast says, and have workable alternatives in our bag of tricks or don’t take off. Generally speaking, the categories refer to the rate at which ice forms. In flying through freezing rain, ice accumulates very quickly and is called severe. Because it’s rain, it has to be falling from an area warm enough to have water. The cue in freezing rain is to climb. If our equipment and aircraft ability is limited, then it’s best to quickly turn back or land. At any rate, we must do something fast, because it forms fast!

I (RNB) remember a DC-2, flown by a friend, approaching Chicago’s Midway. At the McCool Beacon, about 30 miles southeast of Midway Airport, he ran into freezing rain. Midway seemed so close he decided to make a run for it. He landed with almost full power dragging him in. There was so much ice on the airplane that it was necessary to chip it off the fuselage to get the door open! A few more minutes, and he would have spun in. This was during the time, before we knew better; when we thought a DC-2 could fly through any weather. We learned differently. In retrospect, many of these clear ice episodes of the past may have been what we call today Supercooled Large Droplets (SLD ). These supercooled droplets of drizzle and freezing rain can range beyond 500 microns in diameter, give or take ten times the diameter of a previously considered 50-micron maximum that was considered the biggest problem relating to icing accidents. This really didn’t come into operational consideration until the investigation of a fatal regional airline icing accident in 1994, also south of Chicago, which confirmed that the larger droplet issue was a problem. These larger droplets were always up there, but when droplet measurement research took place in the 1940s, the device used for measurement could not pick-up SLD-sized droplets. Scientists knew these larger droplets were up there, and a few worried about it, but the concerns were ultimately brushed aside as minimal, especially from not fully understanding how SLD formed on an aircraft. SLD is, in comparison to all icing issues, still a minority of icing-related accidents, but it’s not a minority problem if we’re the ones in serious trouble! There is a lot of available information on SLD that, as pilots, we need to understand; NASA’s SLD and In-Flight Icing Training media (reference this book’s suggested reading section) is our recommended viewing for understanding, recognizing, and dealing with these icing issues. There’s a lot of excellent, devoted work in those tutorials. The reason SLD is particularly bad comes from the aerodynamics of SLD’s bigger droplets, which causes them to not only stick to a wing and tail’s ice-protected leading edges, but also farther back on the surface, aft of those areas protected by the deice and/or anti-ice systems. This clear ice is bumpy and lousy for our flying surfaces, and then matters get worse when the protected leading edge sheds or melts its ice, forming a ridge behind it, that changes the wing airflow, which effects flight control function. It causes the ailerons to “snatch” into a full deflection of input, with commensurate aircraft response. Because this occurs at higher angles of attack, hence closer to stall, the airplane effectively enters an extreme, aerobatic-like roll maneuver, and is headed down! Only alert and very capable stick, rudder, and instrument flying skills, which includes pushing the nose down—as long as the airplane is still upright—to reduce the angle of attack, and having the altitude to do all this, may save the situation. Also, it is worth realizing that the criterion that certifies aircraft for FIKI does

not consider droplet sizes bigger than about 50 microns. Consequently, even aircraft certified for FIKI conditions are not ultimately designed to deal with SLD. New rules for icing certification in SLD are on the drawing board, but they will not affect the aircraft we are currently flying. Knowing about SLD is a very important piece of the icing puzzle. Realizing this data did not come along until decades after 1940s icing research, it is worth noting that common sense developed from experience, taught the pioneers of this business to stay out of freezing rain, and if we get into it, get out immediately. The real help of knowing about SLD is what it looks like, so we can get a jump on it. SLD indicators include clear icing significantly aft of a wing leading edge; formation all over a propeller spinner, not just the tip; ridging ice on the windshield and along the cockpit’s side windows. We also need to know ways of dealing with SLD operationally, such as flight characteristics and how to fly them, in case we can’t get out of the weather fast enough. Again, we refer to NASA’s excellent media on these issues. A point to consider is that despite new advances in icing forecasts, which include SLD reference, there is still a primary need for the pilot to determine how much ice is up there and to have enough weather knowledge to sense where it will be. We’ll find that if things are turbulent, there will be moderate to heavy ice (big droplets). The same is true for weather that’s intensified by upslope conditions and, of course, flight through fronts will have heavier ice, as will thick stratocu clouds in the lee of lakes. Simply being a good student of the current weather conditions—whether or not it’s turbulent, orographic, or frontal—is the way we decide how tough the ice will be and, of course, the forecast’s prognostication. The task is to take our own look and superimpose that judgment on the forecast, assessing what will be up there waiting for us, and how it may change our flight’s route and progress.

Dealing with Ice A trace or light ice would be found in a thin stratus cloud in very cold air that doesn’t have much moisture. Light ice can, of course, become moderate if we sit in it long enough. We can continue our flight in light ice, assuming we have FIKI equipment, but not unless there is a quick way to get out should it become moderate by forming faster. There should be ceiling below so we can duck under the clouds, or a known and easy to reach top, or a better weather area behind us. The speed with which ice forms is the thing that counts, because it affects what we’re going to do about getting out of it. If it’s light, we can move slower, talk it over with ATC, and have time to work. If it’s severe, however, we might be in an awful hurry, and just tell ATC what we are doing and that it’s an emergency. Before we go any further, let’s talk about deice and anti-ice systems. First, what’s the difference between them? Well, anti-ice prevents ice from forming and

should be on before entering the conditions. Deice takes away ice that has already formed. Now, what do we deice and anti-ice? Key items include pitot heads and other instrumentation probes, static ports, some antennas, and for engines the carburetor, or in the case of a jet engine, the engine inlet cowl, guide vanes, and other appropriate areas. This is obviously important, because if the engine doesn’t run, we don’t fly. We need protection on the leading edges of our wings and tail, as well as some antennas, and the all-important propellers. Everything that heats or dribbles fluid along leading edges is considered anti-ice and should be functioning before we get into the conditions, or immediately upon noticing ice. Deicers are mostly rubber or similar “boots” along the wing leading edge that inflate and deflate by pneumatic operation; we operate these after the ice starts accumulating. We’re going to talk more about these things as we go on, but let’s start with an important look at keeping our engines running. Carburetor heat can be tricky. First, one should have a carburetor air temperature gauge, and then know exactly where the temperature bulb is located in the carburetor system. The reason is this: If the bulb is located in the coldest part of the carburetor, one only needs to pull on heat until the temperature gauge reads something over freezing, like 35 degrees F. If the bulb is located in the scoop, it may be necessary to carry as much as 85 degrees F indicated, to be certain that the coldest part, farther downstream, is above freezing. There is about a 30 to 40 degree F temperature drop from the air scoop to the coldest part of the carburetor. This can lead to trouble if there is not sufficient heat. A pilot might be flying in a condition of cold, dry snow, for example. Generally, this condition doesn’t cause carburetor ice, because the cold ice crystals zip right through the engine and don’t get up to a slushy, freezing stage. But if, in this very cold air, a person puts on heat as a precaution until a temperature bulb in the air scoop reads just above freezing, the temperature would rise just enough so that the ice crystals would begin to melt and then refreeze in the colder part of the carburetor system, causing ice and trouble. I (RNB) learned about this by having a serious double-engine power loss in a DC-2. Fortunately, there was enough altitude to get the engines going again, by leaning and backfiring them to break the ice loose. It’s therefore important to learn where the carburetor temperature bulb is located and how much temperature drop there is through your system. Then we can use carburetor heat accordingly, always having it above freezing in the coldest part of the carburetor, if conditions require heat. Under most conditions, it’s obvious that heat is needed. It’s used, for instance, during wet snow, in rain, in cloud with a near-freezing temperature, even in clear air with high moisture content, if the carburetor is a sensitive one. A sunny summer day may produce carburetor ice, because warm air can hold a lot of moisture. So, if it’s warm and humid, carburetor ice is a real possibility, especially at low power, such as when idling during the glide on an approach to

landing. Sometimes it is difficult to know whether heat is needed or not. A close watch on engine performance will tell. If the airplane has a fixed pitch propeller, watch the RPM carefully to see if it’s decreasing. When doing this, a pilot has to know the RPM previously set and also be certain the airplane isn’t climbing. This is because even a small climb angle will decrease the RPM. If we get an RPM drop, it’s a good indication of ice. Put on carburetor heat, and all of it; if we delay and the engine quits, we’ll not have any heat to do the job. The RPM will drop further, because the mixture has been upset with the addition of heat. Leave the heat on for a minute and then take it all off. The RPM will bounce back to its original value if the ice has melted. This shows, of course, that ice was the problem. Naturally, we don’t want to operate with this off–on procedure. Now, knowing there is ice, we pull on enough heat to get our carburetor temperature above freezing in the coldest part of the carburetor. When we do this, the RPM will drop, because the mixture has become rich. The hot air we are now using is less dense, so there’s effectively less air in the mixture. We lean the engine with the mixture control, and when we do so, most of the RPM loss should come back. If we haven’t a carburetor air temperature indicator, then we put on heat by guesswork, lean out, and keep a close eye on the RPM. If it holds, we’ve got enough heat. If another drop occurs, we should pull on full heat to clean out the ice, and then apply heat again, except this time a little more. We don’t want too much heat; we ought to try and use only just enough. Generally, if too much heat is used, leaning the mixture will not bring back the original RPM. If excessive heat is used, the engine may run rough and lose power. If our propeller is the constant-speed type, we’ll never notice any RPM change, because as the engine loses power, the propeller pitch changes—gets flatter—and keeps the same RPM. The way we tell, then, is by watching the manifold pressure gauge for a drop. That will tell us there is ice. Then we go through the same procedure as mentioned before, except that we use the manifold pressure gauge, instead of the tachometer, to judge power loss or gain. If we change altitude, we’ll have to reset the heat–mixture relationship once leveled off at the new altitude. Most engines use rich mixture for climb, too. With high-powered outputs, as at takeoff, carburetor heat isn’t needed. If one used it on takeoff, there would be a big power loss, and even a chance of engine damage. So we clean out the ice before takeoff, take off without heat, and once in the air watch closely for any signs of engine icing. During climb, most engines do not use heat, but under severe conditions it might be needed. Any deviation from normal climb performance, on instruments, is a hint of carburetor ice. We hear a lot about non-icing carburetors and fuel injection systems being

non-icing. These systems don’t have a venturi, like a carburetor does, with its temperature reducing action, so they don’t ice very easily. However, icing can nevertheless occur in them, because it is still necessary to bring air in from the outside for the engine to breathe. If this air has the proper moisture content and temperature, there is still the chance freezing may occur somewhere in the induction system, even if it is very rare. However, fuel injection depends on air entering from an intake that can get plugged in serious icing conditions; this is known as impact icing. If this occurs, a pressure difference causes an alternate air source to open—or it must be opened manually—which, although it reduces engine performance, nevertheless keeps it going. Clever duct design has reduced this hazard to a minimum, but icing can and does occur. A pilot still has to keep the possibility in mind. Because advertisements say “nonicing,” we should not go along innocently believing it as 100 percent true. In the awful condition where there isn’t enough heat to clear out the ice, a desperate trick might help. The trick is to try to make the engine backfire in the hope that the backfire will clear out the ice. Generally this can be done by leaning the mixture until the engine runs rough and backfires. If it’s successful, the engine will come back in with a great roar as you enrich the mixture again. I’ve done it twice under desperate conditions, once, as mentioned, in a DC-2 and the other time while flying a little Culver Cadet in wet snow. Both times it worked. Jet engines are a much simpler matter. There isn’t any carburetor, and so there isn’t any carburetor ice. However, the air inlets, cowling, and guide vanes can collect ice just as a wing does, and sometimes even when the wing doesn’t, because there is a temperature drop in that big, venturi-like cowling that can occasionally cause ice. It can even cause icing issues in clear air, if the air is very moist, and the temperature just right. Ice affects jet engines seriously, as the inlet airflow is disturbed and cut down. Fortunately, the engines are equipped with hot-air passages within the cowls, guide vanes, and so on. The pilot simply flips a switch, and hot air from the engine is routed through the passages to keep them warm. The only effect on operation may be a slight power reduction from air loss in the engine. Jet inlets may form ice on the ground during a long ground hold waiting for takeoff during high-moisture with low, but not necessarily below-freezing, temperature conditions. The jet inlet causes an air temperature drop, and ice may form on its walls and other areas in the above conditions. The airflow into a turbine engine is very critical; a relatively small amount of ice can disrupt it to the point that when we’re finally cleared for takeoff and advance the throttles, we may get irregular engine action or a compressor stall. So, while holding on the ground, it’s wise to use cowl heat periodically to prevent ice accumulation if the temperature–moisture setup is conducive to ice formation. There doesn’t have to be visible moisture, such as rain or snow, but

simply high humidity; cold fog and wet airport surfaces would be suspect, too. Individual aircraft operating manuals address this with anti-ice usage criteria. There is also a problem with ice crystals and jet engines, usually at the tops of convective activity. In the past, it had been felt there is little if any aircraft icing potential while flying in cloud at temperatures of -(minus) 40 degrees C or below. However, investigation of recent events having power loss at these altitudes indicates enough moisture can be lifted by convective activity, such as thunderstorm tops, causing icing issues. Ice forms at the back of jet engine compressor sections where there is not any anti-ice capability, causing engine surging or even complete power loss. There is also some indication this has an effect on pitot tube icing. The obvious solution for now is avoiding these thunderstorm tops, have our anti-ice on, and abiding by the respective procedures for the aircraft we’re flying, including restarting the engines or loss of pitot systems. Although we talk of radar and avoiding thunderstorms, there are times we’re surrounded in a confused combination of cirrus and storm blow-off, with nothing reflecting for radar. What does help, as mentioned in the thunderstorm chapter, is tilting airborne radar way down, looking for rain down low in the storm, below the freezing level. And yes, it can rain way up high, above that freezing level. This obviously does not affect general aviation operations, more at home in lower altitudes, but does include corporate jets. The main point is to be certain that heat is used whenever there is a possibility of icing. All engines, piston or jet, get their deicing power from heat generated by the engine, so it’s obvious that if the engine isn’t running, there isn’t any heat. Don’t let it lose power. We now have pitot heat on to keep the necessary instruments working, and engine heat. Next in importance is the propeller. Jets don’t have this problem, of course, and that’s a very nice part of the jet world.

The Propeller Is Important Propellers get ice, and when they do, their efficiency drops quickly and then the engine we’ve kept running is just slinging an icy club, beating up the air but not doing much pulling. Ice can also unbalance a propeller, creating enough vibration to shake your teeth. There are two ways to clear propellers of ice. One sprays fluid on the leading edge of the propeller to melt ice, and the other method anti-ices the blades by applying heat to the leading edges. Without either of these systems, there are silicon-based chemicals available that can be spread on the leading edges of a propeller to help keep ice off. This is a stopgap method and not what we should depend upon over the option of a mature propeller deice/anti-ice system. These same products, when rubbed into the surface of the wing deicer boots, make the ice come off more easily, because

pieces of ice don’t tend to stick to the boot. The preparation doesn’t have a very long life and is washed away when the aircraft flies through rain, necessitating renewed application. There are two ways to use deicing equipment. One is deicing, and the other is anti-icing. In the first case, one waits until ice has formed and then turns on the fluid or heat to get rid of the ice. Unfortunately, the ice never comes off evenly, and when it comes off one propeller blade and not the other, the unbalance makes a terrific vibration. Also, on a multiengine airplane, the ice slinging off often hits the fuselage with a loud whack that’s disturbing to one’s nerves. It doesn’t hurt the airplane particularly, but any old DC-3 will show dents on the side of the fuselage next to the propellers, where hunks of ice have beaten on it through the years. More currently, we see abrasive plates over the fuselage skin, their paint often the worse for wear. Sometimes, however, the prop ice sticks well and will not totally clean off. The better method is to use the equipment as anti-ice. This simply means to get fluid or heat on before entering icing conditions so as to keep the ice from ever forming. If there is ice on a propeller, and the deicing method used is having trouble getting it off, try running the RPM up and down in surges to give extra, and irregular, centrifugal force to help sling the stuff off. Propeller ice will often form before visible wing ice, and if one is flying in cloud and an airspeed loss occurs without wing ice, it may be because of propeller ice. I saw this when doing research work with a B-17. We had a stroboscope to look through. It “stopped” the propeller visually while it was spinning at its normal RPM, and you could look at the prop as though it were standing still. A B17 was convenient for this, because you could see the props closely from the navigator’s station in the nose. It was amazing to me to see ice on the leading edge of the blades when we didn’t have a bit anywhere else on the airplane. And this happened quite often. So don’t be bashful about getting the propeller anti-icing gear into action well in advance or under any suspicious condition. The propellers are most important, and in decades past, with less-efficient and functional boots, if one could have either wing deicers or clean propellers, the choice would be propellers. If they were doing their work efficiently, we could pull a lot of those old thick-winged, lower wing-loaded, ice-covered airplanes around the sky—most of the time. However, today, we’ve learned this should be considered a last-ditch situation, and it’s better not to get ourselves into these predicaments in the first place. We should have an approved ice protection system before even considering we’ll seriously fly ice.

Wing Deicers and Anti-Ice

As mentioned earlier, we have three kinds of devices for removing ice from wing and tail leading edges: pulsating boots, weeping fluid, and hot wings. The boots are always deicers, while hot wings and weeping fluid are considered for antiicing and are most efficient when activated before entering icing conditions.

Boots Years back, there was question of how much help deicer boots really offered. Thousands of hours of weather flying was done without boots being very effective. A good example of this occurred in the B-17, in which I (RNB) did a lot of research flying. The boots, during those difficult times of WW II, were made of something less than the best rubber and we continually had problems with them developing tears. Each time we had to replace the boots, it was a long maintenance job. Finally, we had a bad tear and couldn’t find replacements. We had the crew chief take them all off and finished 18 months of weather research flying, a lot of it in ice, without boots on the airplane. I was particularly fussy, however, about keeping the propellers clear of ice and the engines running. An aspect worth considering is that the research B-17 was much lighter than one prepared for a real bombing mission, so it had a more favorable power-toweight ratio. Having power to pull through ice is a big help, although this is not a conclusive concept, and certainly nothing on which we can pin accurate criteria of operation. Consequently, it’s not a reason to stay in icing conditions. Despite boots being far better these days, unless we are in light or a trace ice, they or any other ice protection should not be considered as a means to fly continuously in ice. At the risk of boring the reader, we repeat that the worst ice offenders on the airplane are the antennas, landing gears, probes, and places where we cannot place ice protection, let alone heated fuel vents so the engine keeps running. A concern was to have the ice break off clean, instead of having a leading edge with ragged pieces of ice sticking out. This can be worse than a smooth coating of ice. In years past, we’ve seen cases where the airplane had a smooth coating of ice when the boots were turned on. Then the ice broke up in chunks, with pieces left on the airplane, even big hunks that stuck on the leading edge and went up and down with the boot, but never blew away. Sometimes the airspeed fell off 10 knots after the boots were turned on and the ice cracked. This leads into techniques for operating today’s boots. In the past, it was felt ice should be allowed to build up to ¼ inch to ½ inch before the boots were actuated. It was felt that as the boots pulsated up and down, a thicker accumulation theoretically broke off in a manner that allowed the airflow to blow it off and away. Then when the boots did their job, it was time to turn them off and wait until another coating of ice formed, repeating the process.

Today’s boots seem to be effective even as the ice begins to form, which is why many manufacturers recommend turning the boots on at the first signs of ice. Many systems have automatic off–on scheduling, which not only seems to do a good job, especially if related to an icing sensor, but also keeps us from forgetting them if things get busy. These systems seem pretty clean, and any hunks of ice tend to blow off from continued actuation. One other concern is that if an aircraft is near a critical angle of attack for its contaminated wing, that ¼ inch, give or take, of ice, could be the critical amount needed for stalling the ice-altered wing. This is, of course, variable due to many factors, including power-to-weight ratio, type of aircraft, and how we’re flying it. In other words, unpredictable. Also, an aircraft’s stall warning works in relation to a clean wing—one without ice—so possibly, it will not warn us before stall when in an icing situation.

An airplane that flew through a lot of ice! The black deicer boot worked hard, but still had pieces of ice stuck to it. The ice on the wing’s bottom is thick, and a ridge of ice sits aft of the deicer boot. All of this is an aerodynamic nightmare. The ice as seen indicated SLD-type icing or maybe an aircraft struggling along at a high angle of attack or maybe both. Even with approved FIKI equipment, this was a dangerous situation. We should not consider this picture as a reason to fly in icing conditions. (PHOTO COURTESY OF PURDUE UNIVERSITY) Today, deicer boots are bonded to the aircraft making a cleaner, more aerodynamic fit, as compared to days past of screwed metal strips holding them in place. Also, better designs of inflation tube have seemingly made deicer boots a much better benefit for today’s aircraft. It’s also worth mentioning no aircraft has been approved for FIKI (known icing conditions) without some form of wing anti-ice or deice; the latter being boots. Overall, the recommended procedure for

operating deicer boots is to consult the aircraft flight manual, then do what it says.

Hot Wings Hot wings are something different, as the leading edges are heated, usually from jet engine bleed air, although some are electrically heated through boots containing heating elements. They are best used as anti-icing. In other words, they are turned on and the wing is heated before getting ice, so the hot leading edge never lets ice form. When used as deicers—that is, turning them on after ice has formed—they either melt the ice, or break the bond which lets the ice blow off. Sometimes, when the ice melts, the water can run back on the wing and refreeze, forming a spoiler-like ridge on the top of the wing. In theory, a ridge forming behind the heated leading edge may affect airplane performance, or roll-control issues. This varies with each aircraft’s design, and ultimately tests approving certification are reflected as operating procedures prescribed from that aircraft’s flight manual. Overall, on jets, melted-ice ridge issues seem rare, if at all. Also, a hot wing, when using bleed air for its hot air source, is dependent on a certain level of heat. Consequently, a bleed air–dependent system often requires a minimum engine power level during its use for anti-icing; bleed air temperature increases as a function of increased power. Another reason hot wings are best used for anti-icing is that with this adequate heat, the ice is not just melted, but vaporized; hence no water to run back on the wing. However, if we turn on heat after an accumulation of ice, as the heat process reaches normal temperatures, there is a brief period where it passes through the melt-only temperature, creating water, before enough heat for vaporization is produced. This water could run back on the wing, and may leave a small ridge, but a good hot wing works well and quickly, so “ridging” is usually a minimal issue. Again, following the aircraft’s certified procedure of anti-ice use is the way to go.

Fluid Anti-Icing This system pumps a glycol–based antifreeze solution through panels having many tiny, precisely drilled holes. These panels are mounted on the aircraft’s flight surface leading edges. It also is distributed on the propeller and windshield, similar to when alcohol was used for this same means as far back as the 1930s. The fluid forms a protective film over flight surfaces, which according to manufacturer data chemically breaks down the bond of ice to the airframe, where airflow and aerodynamics remove the ice. The system can be used as either an anti-ice or deice system, depending, of course, on whether it is turned on before ice formation or after. The fluid’s flow over the wings and tail has the benefit of coating the surface aft of the leading

edge dispersal, which in theory assists in preventing run-back ridges, as well as potentially helping prevent SLD icing on wing surfaces; however, we caution that this is not considered a viable reason to fly in SLD icing conditions. As a matter of fact, the manufacturer data states their system, like any good deice/anti-ice system, buys us time as we seek nonicing conditions. The system has a successful operational lineage since the 1960s, as the approved system for the DH-125 business jet. Many say it worked very well. Known as TKS, this system is available today on quite a few new aircraft, including single-engine piston airplanes, as well as being retrofitted to many older designs. There are FIKI-approved aircraft that have TKS and some that do not, so if one seeks such a system, one must research this through the aircraft flight manual and other paperwork. The only limitation seem to be fluid capacity, but most airplanes seem to hold about two to three hours’ worth at continuous operation; like fuel, this just requires attention and common sense. And what does TKS mean? It is the initials of three partners who came up with it in the early 1940s. Tecalemit was a pumps and valve expert, Kilfrost came up with the fluid (and we see their products today squirting over aircraft in hideous, frozen weather), and Sheepridge Stokes figured the aerodynamic magic. Considering this system is well appreciated by many users today, one again asks what really is new in the flying business.

We Have to See An important item that needs deicing, or anti-icing, is the windshield. If we make a low approach through icing conditions and get the windshield covered with ice, we cannot see to land. The ways to solve this are: 1. Hot windshield, either through the whole thing like jets and turboprops or a dedicated heated unit mounted over the windshield, in front of the pilot. 2. Alcohol or TKS fluid to squirt over the windshield. 3. A window one can open to see out. Historically, we have handled the windshield ice problem in the reverse order. Back in DC-2 and early DC-3 days we (RNB) all carried a putty knife in our flight kit. It was used when ice covered the windshield. We’d open the side window, reach out into the icy blast around to the windshield, and scrape off enough ice to give a small clear area to peek through while landing. Then we got alcohol. This would squirt across the windshield and as it melted the ice, the windshield wiper would carry the ice away or knock it off. It was smeary and partially effective. We still carried putty knives. An occasional heavy coating of ice wouldn’t yield to either putty knife or

alcohol, and there were cases where the pilot bashed out the windshield with a fire extinguisher to have a place to look out! Now we have heated windshields that seem to do the job well. All the trying days of fire extinguishers, putty knives, and alcohol are taken care of by flipping a switch.

Windshield ice! It’s an older picture, but ice does the same, new or old airplane. This aircraft had fluid deicing (alcohol), which we see only made a futile dent in the issue on the left lower side and under the eventually stuck windshield wiper. Landing would be a big issue! You might see enough out the curved front of the side window, or maybe not. However one does it, keeping the windshield clear is a very important part of ice flying. If the methods available are marginally adequate, then a window that can be opened for viewing is a must! Flying any airplane that does not have a window that can open, or at least enough of a look to land, is something to ponder. On a single-engine aircraft, a covering of oil from a bad leak can make a windshield no more transparent than a solid wall, let alone a coating of ice. Some general aviation aircraft, as we know, have generous side windows that open, like high-wing Cessna’s. But when we’re down to those small side windows that open, which are located in the main side window, windshield icing, and for that matter previously mentioned heavy rain, is an issue to contemplate. In kind of an interesting story of habit patterns, the 747s, which your first author flew when they were new, didn’t have a window that opened; it was possibly the first transport ever certified that way. The old timers who first flew it

—most who learned to fly in biplanes and started airline flying in DC-2s—got itchy about no window to open, but soon realized such was not a problem, due to excellent heated windshields and good wipers. Most other Boeings do have windows that opened, and although there we’re never issues of seeing out the windshield, it was helpful for quite a few things, including views of the wing, engines, and airport surface in lots of lousy winter weather. You could also run your hand over the outside of the fuselage to see what the precipitation was doing. The only personal window complaint was in the 727; on the ground, and obviously not pressurized, a good deicing would leak around the frame, dribble on us, the flight kit, wrinkle some charts, and drip into your coffee, making it taste weird. In summary, we’ve taken a look at the protective devices against ice. They don’t cover the entire airplane. Even if propellers and wings are kept clean, ice will build up in other places, causing drag that eventually will be very serious, which gets us back to the original statement that the first rule of flying ice is: do something to get out of it as soon as it occurs .

How We Fly Ice Ice flying begins before we ever leave the ground. A number of things need checking. First and most important, is there any frost or ice coating on the wings? If so, we have to get it off before takeoff. The rough surface of the ice or frost can ruin the airflow over the wing, so that the takeoff run is very long and liftoff likely to be impossible. A Bonanza tried to take off here in Vermont on a lovely fall morning. There was a slight coating of frost, thin enough so the pilot evidently thought it would not affect the aircraft’s performance; he elected to go. The airplane never got off, piling up at the end of the runway and burned—three people dead. Probably everyone is aware of high-profile accidents because of frost or sticking precipitation on wings. It’s a no-win situation and so unnecessarily sad, because when we’re safe on the ground, we have complete control and can get the stuff off before trying to take off. It isn’t a matter of being in a situation; it’s a matter of creating one by impatience. Remember, the most innocent-looking thin coating of frost is dangerous, and flight should not be attempted until it is removed! Removing frost, frozen rain, snow, or whatever has dirtied up the wing has two aspects: one is deicing, and the other is anti-icing. If it’s a nice day, and we want to remove the contaminates, to use a fancy word, we wash it off with a glycol–based deicing fluid, very often mixed with water and generally available at the FBO. This process of removal is deicing. If, however, it is precipitating, and we are going to take off, then anti-icing is necessary, because the glycol–water mixture used for cleaning the wing will only prevent falling precipitation from freezing on the airplane for a limited time. So

now, after clearing our aircraft of frozen contamination, we have another application of fluid applied to prevent further contamination, which must do so over the time it takes us for taxing to the runway and taking off. The kind of fluid we use for this anti-ice process varies with precipitation type, intensity, and outside temperature, as well as the type of fluid used. There are currently about four fluid grades, often known as Type I through IV, offering different viscosity and subsequent “hold-over” times, again depending on precipitation type, intensity, and outside temperature. The hold-over time is how long we can sit there in whatever type of frozen precipitation, having it absorbed and melted by the fluid, with the flight surfaces supposedly clean for takeoff. When we takeoff, we want these fluids to shear off the flying surfaces before our takeoff speed. Some of the thicker fluids require higher jet rotation speeds, so slower aircraft will be using thinner fluids; it’s something to look into before operating in these conditions. Depending on the fluid type, dilution (realizing some fluids must be diluted, some can go either way, and some can only go full strength) and all the other factors mentioned, these fluids handle almost all freezing precipitation as well as rain on cold soaked wings, except freezing rain; that’s a no-go item. Frankly, taking off with freezing drizzle or light freezing rain isn’t such a fuzzy and warm feeling, but then again, we evaluate if we’re a light single or big jet. So if the taxi is long, and takeoff delays are in progress, you may be on the ground for considerable time with “stuff” falling and collecting on the wing. Depending on the extent of one’s evaluation procedure, it can become complex, with iffy factors still prevailing. On determining your precipitation type and temperature, intensity comes into play. That may cross-reference reported visibility. Then we look at the type of fluid used, not just in number but manufacturer. Is it diluted or not? Finally we look at guidelines, which can be a whole section in our operating manual. It is there that we find out how long we can theoretically wait in the same type of precipitation, and still have a clean wing. For example, a generic Type II table, using the stuff at 100 percent, shows that on a −2 degrees C day with light to moderate snow we can sit in a range of 40 minutes to an hour. If somehow light rain is mixed with light snow, we must revert to the light freezing rain table, which now says we are good for just 40 minutes. However, if it was applied as a 50/50 mixture of water and fluid, that 40 minutes slips to 8 minutes. All these numbers mean the same or less precipitation, temperatures staying in range of the criteria, and so on. If an aircraft in front of you is blasting snow all over your airplane, or the wind increases, doing the same thing, the fluid may be sheared off before we start our takeoff roll, let alone the blowing snow coating our airplane. Then comes the moment of truth; we’re ready for takeoff and wonder where we are in that time range of 40 minutes to an hour. If it’s longer than that time envelope, we usually return to the ramp and have it checked; reapplying fluid and

starting the process all over again. So, the responsibility is dumped on the pilot, realistic or not, to be certain the wing, tail, and engine inlets, are clean before taking off. How are we sure of this? Taking a look at the wing, under strong light if at night, can give a false impression, because the ice might be clear and the wing may look free of it, when it really is not. Using a flashlight through a cabin window is almost useless, as the light glares back in your face. The only sure way is an inspection from the outside, which is tough to do at a busy airport just before takeoff. Imagine climbing out to do that at runway’s end, airplanes waiting behind you, wind blowing, wet snow falling, and you commence a methodical walk around inspection. Kind of unrealistic, but it is your responsibility, so if you are uncertain, then the only thing to do is taxi back, inspect the airplane from outside, and deice it again if necessary. Unfortunately there’s no pat procedure or method, and, as said, it’s the pilot’s responsibility. As the FARs say in Part 91.3(a), “The pilot in command is directly responsible for, and is the final authority as to, the operation of that aircraft.” And that goes, be it a Piper Cub or a Boeing 747. An important point we feel worth emphasizing: don’t think you can blow snow off the wing! If it’s super dry and just resting there, perhaps you can, but if it sticks at all, or there’s something sticking under the dry snow, we’ll never blow it off. This idea is an invitation for trouble. Try it on a car someday; even going like crazy down the highway not everything comes off, which is about the takeoff speed of a single engine airplane. Another issue is when we brush snow off an airplane and think it’s clear, but under the snow was frozen contamination stuck to the wing. If we don’t run our hand over the surface we’ll never know, so we need to inspect the wing carefully, running our hand over it, getting a ladder if we need to, seeing what’s under the dry snow. So, if it’s only dry snow, get a broom and sweep it off! If, for some dumb reason, we try to take off with frost on the wing, or other frozen precipitation, we may become airborne, but will probably be unable to climb out of ground effect. The airplane will become very unstable laterally, and it will want to roll side to side, as though falling off on a wing at stall, because that’s what is happening. Fly as best you can, you might fly out of it, but chances are you’ll never get out of ground effect, which is about half the wingspan high. Most times, the airplane will not even get that high, but will just charge off the runway’s end into whatever awaits. This is all very dangerous business.

Is Your Airplane Equipped to Fly Ice? One may ask questions such as, “How much ice can a Cessna 172 carry?” How much an airplane can or cannot carry isn’t the question. The real question is, “Does FAA say the airplane can be flown in ice?” If it isn’t FIKI-approved, then we don’t have any business flying it in ice. Just because an airplane has deicer

boots and heated propellers, that does not mean it’s FIKI approved; we dig into the paperwork and find out. The FAA approval for an aircraft to fly ice isn’t simply a test of how much ice it can stagger around with, but it is an examination of the entire aircraft and its systems. Do the fuel vents stay open, do controls ice up, do air intakes become clogged with ice, can the windshield be deiced? A host of questions, and if our airplane isn’t FIKI-approved, we may not simply get in trouble because of the ice on the wing. What if the controls ice and cannot be moved, or a fuel vent clogs with ice? Think about all those things and realize if the airplane isn’t ice-approved, one hasn’t any business flying ice in it. A lot of things could happen.

Propellers, Jet Inlets, and Other Fixtures As previous mentioned but never too many times, the propellers should be clean. On damp, misty, coldish days, it’s wise to use anti-icing on the propellers right from the start of takeoff. There is some evidence that one can get propeller ice in clear, but very humid, cold air. Under similar conditions, a jet engine inlet may ice, and so engine heat may not only be wise, but is most likely required as standard procedure. The criterion for this usually includes temperatures that are above freezing, because, as also mentioned earlier, air expansion at the engine inlets causes a cooling process; kind of like the carburetor routine. Depending on the engine and aircraft, anti-ice is usually required between +6 to +10 degrees C or less, and when visible moisture is present. That definition includes individual or combination amounts of rain, snow, frozen anything, wet airport surfaces, and fog; this latter criteria is based on airport visibility of a mile or less. Obviously, we consult the aircraft flight manual for the definitive word, but if stuck with nothing, these are some things to think about. Back to our bad weather checks, the airplane’s controls should not have any ice obstructing their movement, and the landing gear should be clean, especially if it’s retractable. Check the pitot head and static sources closely to be certain they are not blocked by ice or frozen slush thrown up by the wheels during a previous landing or by precipitation that stuck on the airplane while it was standing. If it’s very cold, be certain there has been heat applied to warm the instruments. A cold gyro may be slow in coming to speed, and its action will consequently be sluggish, which would be bad if one took off and went on instruments quickly. The windshield may fog up during takeoff, and we’d best be prepared to defog it with whatever means are available. After an engine is started it’s important to warm it up thoroughly, so that when we take off, it will put out its normal power and continue to do so at its maximum power.

Ice Flying Starts on the Ground

Taxiing can be quite an interesting experience on icy, frozen, and snowy surfaces. First, if there’s snow and it has been plowed, it is important to be certain that when turning, wingtips, and the tail will clear the snow banks, especially if we are in a low-wing airplane. The runway surface may be ice-covered and slippery, so a combination of slick surface and strong wind trying to weathercock the airplane makes taxiing an adventure. First, taxi slowly, really pussyfooting along. The most important point is to use the brakes carefully. Use them in little bursts, but don’t lock the brakes. If we do, as soon as they lock, the wheel stops and slides, ice-skate fashion, over the surface. Tapping the brake on and off at short intervals will give braking for an instant, each time the brake goes on and then is released just before the wheel would stop and become a sliding ice skate. I (RNB) operated my B-17 in the Aleutian Islands of Alaska. The weather there often causes sheet ice to cover the runways and taxiways. The winds blow hard, the taxiways are narrow, and a B-17 with its big fin wants to swing around like a weather vane. I had excellent luck getting around by using the quick onand-off braking method. Although weather cocking is usually thought of as a problem for aircraft with conventional (tail-wheeled) landing gears, we can feel the tendency in any aircraft. Even larger airliners get a noticeable shove in a healthy crosswind and if we’re taxiing on a slippery taxiway, there can be issues. It’s a goosey feeling when a gusty wind keeps trying to shove a big airliner sideways, while each stop gives a little slide and tiny weathercock; especially someplace where we taxi right next to a body of water or an embankment. Sometimes, on slick taxiways, it’s impossible to get the brakes to hold while running up the engine, so one might have to run them up while sliding. This takes thought and planning and careful observation of where one’s sliding. The start of takeoff can be swishy as a crosswind tries to slide the airplane around before there’s enough airspeed to make the rudder effective for steering. It takes care, and the winter isn’t any time to do things in a rush–rush fashion. This is an other example of where the modern world still needs good old-fashioned stick-and-rudder skill. We need to roll our ailerons into that upwind wing and work the rudder in small but timely corrections, just like one should do when flying a tail-wheeled aircraft. Turning onto a slick runway at high speed for a running takeoff is a very poor practice. The nose wheel will not have any traction, only skidding as we use it to straighten out the airplane and aim down the runway. The nose wheel may turn, but the airplane will not, and everything will slide sideways out of control, headed for the boundary lights.

Where We Find Ice

Let’s look at the places we find ice and how to get out of them. As always, we are back to our first look at the general weather picture. With today’s icing forecasts, especially the graphical ones, we can get a good look of expected ice along our route, both from overhead and a profile view. However, it is still important to see where the fronts are, because we find the most ice in the fronts and lows, and being the most difficult ice, it’s what we want to avoid. Ice can be found in large amounts out of fronts, too, but it’s easy to avoid if a pilot understands the weather picture. Again, forecasts are aids to the more important understanding of the weather’s big picture. Should we pick up on the weather systems moving, say, at different speed or magnitude, we’ll have an idea where changes to the icing may be, because we understand the original synoptic makeup. Ignorance can find a pilot desperately in trouble when it isn’t necessary. The classic case of this is the Allegheny Mountains after a low and its associated fronts have gone off the East Coast, out to sea. Although the fronts have gone, we find the country from Harrisburg, Pennsylvania, to Columbus, Ohio, cloud-covered. The mountain weather-reporting stations are grim: low ceilings, snow falling, and visibility nil. A pilot flying low, trying to stay VFR, would have a desperate time. It would be impossible to cross the ridges, as they would be in cloud. A pilot flying a few thousand feet higher, on instruments, would find they were getting ice at an alarming rate. A clever pilot would know that all this was an air-mass condition, with reachable tops above, and it is possible to be sitting in sunshine on top of a seemingly endless blanket of white, relaxed and comfortable. Countrywide, such air-mass stratocumulus decks are common in winter after fronts pass. The more notorious of these occur not only in the Allegheny Mountains but in all the area downwind of the Great Lakes, sometimes for hundreds of miles, the mountainous Northeast, and the Pacific Northwest, downwind of the ocean. What’s happening is the new cold air is unstable, has moisture, and builds a cloud deck. On the ground, after a front has passed, we are often under clear skies. Then cumulus start to build. At first they are pretty, white, scattered cu, then they become broken and dark, finally turning into a gray overcast sky that spits snow in blustery cold winds. This is the real cold air mass moving in. That cloud layer has ice in it. The only decent place to be is on top. The tops will vary in height, depending on a number of things. Tops are higher in mountainous areas or to the lee of large bodies of water, such as the Great Lakes, where the air picks up moisture. The tops will be higher when we are closer to the frontal system, though not directly behind it, because there is often that clear area where the new unstable air hasn’t had enough time to get in and start its action. This clear area isn’t very wide. It often fools people into thinking everything is wonderful ahead, that the front has passed, and now it’s clear. These hopes fade at 100 miles or less along the way, as clouds begin to

form, the bases get lower, and cloud tops get higher. As we get farther and farther from the weather system, the tops are lower, the bases higher, and the showers less frequent, until they die out altogether. This happens because the air has been in the area long enough to be modified, and its instability is reduced as the air temperature and ground temperature become more nearly the same.

Temperature Again This temperature difference between ground and air is the reason why we often see beautiful, clear, cold, winter nights and, as we look at the sparkling stars, decide tomorrow will be a lovely day. Tomorrow turns into an overcast, cold, gray day. Why? Simply because when the sun came up, it warmed the ground; maybe it didn’t feel warm, but it was warmer than the air, and this started the air rising and triggered the same process that makes cumulus clouds in summer.

Where Are the Tops—and the Bottom? If we are going to fly in the area of the heavy deck with its ice and snow, we should try to learn what the tops are before we take off and start climbing to find them. Area forecasts give us an idea what they as a general area, and graphical ice forecasts let us search altitudes where ice begins and ends. We talk with the FSS, asking for PIREPs or searching for them on computer weather sources. A phone call to a local approach control or even an ARTCC facility can access aircraft already up there. And of course, ask around the airport, whether of a pilot who just landed or an arriving aircraft on the radio, even an airliner. The airline pilot is happy to help out. Once airborne, we can ask aircraft ahead their conditions or contact Flight Watch for PIREPs. Most importantly, we shouldn’t keep what we are experiencing a secret. Call Flight Watch or FSS, and more locally, use the current ATC frequency to give a PIREP. This is especially important if we are the first ones out there, maybe early in the day. We tell them what ice we found during our climb and what we have for the tops. If we are climbing to top a deck, it’s best to climb quickly—not at a nosehigh, staggering angle so that ice will form back under the wing and hurt, but at high airspeed, with plenty of power. Stratocu clouds have the most ice near the tops, especially the SLD type of ice, so don’t struggle along clipping through the tops; get up and out of the clouds. Occasionally there are bits of trickery in getting on top. Out of Pittsburgh, Pennsylvania, headed east, the highest tops and toughest ice are located in the mountains east of Pittsburgh, over the Laurel and Chestnut Ridges. Taking off and then climbing toward the east means one climbs through the thickest clouds. To the west of Pittsburgh, of course, the land is lower. Back in DC-2 and DC-3 days,

we often got a clearance to take off and climb toward the west. The tops would always be lower that way. Once well on top, we’d turn back east for New York. It was a way to get up through the minimum amount of cloud. The tops to the west would often be 7,000 feet, while the tops over the ridges might be 12,000 feet. We can still use this today, when flying many types of general aviation airplanes. Flying in winter over the mountains of the far Western United States can be difficult, with a combination of moist Pacific air being lifted up the mountains of the coastal ranges, the Cascades and Sierras. It can be a problem, at various times, from the Canadian border to Mexico. The fact that the airplane must operate at extreme altitudes because of the high mountains—higher than those of the eastern states—adds a trying factor. In fact, with certain lower-performance aircraft, it is an impossible one. While the West Coast is generally blessed with good weather, when it is bad, it is very bad: be certain to check what the tops are before takeoff. If planning to fly on top, we don’t experiment and find ourselves still trying to climb with lots of ice on the aircraft and no tops in sight! Descending through icy decks should be done quickly without being wild and panicky about it. Ice raises the landing speed, covers windshields, and makes a low approach tougher. We don’t want to get any more ice than necessary during the descent. ATC will often hold or dawdle you about in the icy deck, and when they do, it’s time to tell them that you are getting too much ice and you don’t want to sit in the deck any longer than you have to. They’ll generally help if you let them know you have a problem, especially if you request an altitude change and are willing to accept a heading change to give ATC a broader range of options to clear traffic and get you down. We need to know where we’ll break out; in other words, where are the cloud bases? If it’s a long way down, through icing conditions, we may want to request staying on top as long as possible, then making a “slam-dunk” down through the mess, on to the approach and landing. Obviously, we don’t want to get so hyped about the “slam-dunk” that we are late in slowing down and setting up a stabilized approach. These types of descents can be an issue with piston-engine aircraft, where we are concerned about carburetor icing during low power and rapid engine cooling. Also, descent can be helpful PIREP time; both for us and sharing our conditions for others. A good example is the northwest approach to Burlington, Vermont. The upslope from Lake Champlain can create a quick but significant clout of ice as the approach passes over the Green Mountains before starting down the glideslope. A good PIREP to the tower and approach control can be a big deal to someone unaware, who may suddenly find a nice chunk of ice buildup just before landing; especially if they are flying an aircraft that is not approved for icing conditions. Their option might be letting down away from the mountains on another approach, where there is usually better ceiling, or maybe even scattered clouds, and entering the landing pattern for a nice VFR event.

These are times that having really good hand-flying instrument skills are a big help. Hand-flying may facilitate a quicker approach—hence less time to build ice —than using an autopilot. One day I (ROB) watched my father shoot a step-down VOR approach into Montpelier, Vermont, in a Cessna 172, with a stratocumulus deck hovering over the higher hills of the area. The deck was not too thick, but nevertheless he wanted to get through it quickly as he suspected some ice, despite no reports in the area. He’d been retired from the airline for quite a few years, but had kept his flying sharp. Hoping to find a hole in the clouds from downflow of the local mountain wave, there wasn’t one—wave or hole. At least it wouldn’t be too turbulent, a fact my mother would appreciate, as she sat trustingly in the back. Neither of us were thrilled about getting ice, and considered overflying Montpelier for Burlington with somewhat better weather. However, after a chat, we agreed the bases were well above minimums, and the deck not too thick, so he said: “I’ll fly it like a DC-2 getting a load of ice.” I figured this ought to be interesting, and down we go. We entered the cloud tops with our speed up, a good rate of descent, carburetor heat out, window heat full (and fairly useless), quickly crossing the final approach fix outbound. He pirouetted through a timely procedure turn, yet with sensible bank angles and precise flying, then made the “dive and drive” to breaking out of the clouds and a nice landing. We had maybe ⅛ inch of ice, but the disclaimer says that he didn’t fly ice much, if ever again, in our trusting 172. Overall, despite all his experience, he was a really conservative aviator. Truth is, years later, in his late 80s, he used to practice this stuff under the hood in VFR conditions, using just the turn and bank, steep turns and all. So, all said and done, it’s important, then, to know if cloud decks are air mass or frontal, and where both the tops and bottoms are lurking.

Fronts and Ice Knowing the front locations is the most important factor in foreseeing ice, but there are other hints, too. If a cloud deck exists, and the surface reports show a good, solid wind of at least 10 knots (not a light, variable wind) from a direction we normally associate with good weather (like northwest in the East Coast area), we can feel pretty certain that the clouds are air mass and not frontal. If we are on top, it should be clear above us, or perhaps we may have only a very high, thin cirrus deck left over from the system to the east. If, however, thicker high clouds are overhead, and we are between layers, we’d better check to be certain that something isn’t stirring in the general weather picture. The first thing to do is look westward, or in the direction away from the weather movement. If these high clouds thin and decrease in that direction, with perhaps blue sky peeking through and a general clearing “feeling,” then the clouds above us are probably leftovers from the past weather system. If, however, it looks just as cloudy to the west, we must be suspicious of

another weather system moving in, or the one to the east being stalled, or perhaps an occlusion bending back. With this gloomy outlook, it’s time to check surface reports in all directions and try to get any new or revised forecasts, and if we have the instrumentation, look at a satellite, surface chart, or radar. Once I (RNB) carried blank maps in my flight kit and would draw up a crude weather map from weather reports received in the air. I could quickly see a change in wind circulation and begin to notice a change in weather patterns. This proved to be useful in a number of ways, like seeing a trend for deteriorating weather or for better weather, and it was excellent training to develop a deeper awareness of what weather does. But you know, if we are still flying an airplane without electronic displays or portable electronics, this is a perfect example that good habits of the past are still quite valid. Air-mass clouds may have snow showers, but they don’t have large areas of steady snow. Steady snow or rain indicates that something more extensive than air-mass weather is in progress. This we can see from surface-weather reports. An exception is in mountains with unstable air being lifted. Then the snow might be steady with very low ceilings on the upwind side, but just snow showers elsewhere. The steady snow is the result of the wind constantly lifting the air up the mountain. The same effect can be found in the lee of lakes, especially the Great Lakes. Even Lake Champlain in Vermont and New York can cause heavy snow downwind from it and is given a further boost from upslope against the mountains to the east. This is commonsense stuff we learn from weather study, and something we won’t get from electronic weather; it will tell us what it’s doing, but if we know why, we can often spend less time staring at weather information and more time looking out, making overall go–no go decisions, and flying the airplane.

An Ice Airplane When we fly fronts that have ice in them, we need the proper equipment. This time, the equipment is the airplane itself. It should have the ability to climb at a good rate to a fairly high level without much trouble, 15,000 feet for example, and it should have a good enough cruising range to give a wide choice of alternate airports. If it has a piston engine, it’s likely turbocharged, and whatever the power source, it’s approved for flying icing conditions.

Not Always in Clouds on Instruments We have to define something before we can go much further in ice flying. That something is the difference between being on instruments in a cloud, and being on instruments but not actually in solid clouds. Sounds a little complicated. Say we are flying in dense haze or smoke with a lower cloud deck that obscures the earth.

In this condition, we are not really flying in a cloud, but we can’t see anything, so we’ll have to fly by instruments. Now, take this condition and make the haze snow, and we have the same thing: We are not really in a cloud, yet we are on instruments. This occurs very often in winter instrument flying. It’s not a question of cloud density; it’s just that we are either below a cloud deck or between layers of clouds in snow or haze. Whenever this occurs, we do not get ice! The only time we’ll find ice without cloud is in freezing rain or drizzle, whether it’s the sole precipitation or mixed in with the snow. Otherwise, ice is in an actual cloud, where we find those supercooled liquid droplets. We can fly at times for hours in such cloudless instrument conditions and not get any ice, even though it’s below freezing.

Warm Front Taking it from the ground up, as if we’re taking off and climbing out of an airport, the structure of a warm front, and any condition that involves warm air overrunning colder air, is something like this: At first there probably will be a low cloud deck, its base at perhaps 500 to 1,000 feet. This deck is caused by the precipitation falling into the colder air, and its thickness will depend on how long the precipitation has been falling and how close we are to the frontal surface. It may be scattered and only 1,000 feet thick, or it may be solid and 8,000 feet thick. It will have ice in it, probably light rime ice, although it can be moderate at times. As we climb through this layer, it will be snowing, the windshield will get ice on it, and so will the wings, as will other parts of the airplane. We’ll need to have our anti-ice and deice systems working. The wingtips will appear fuzzy, and we will see the shredded cloud slipping over the wing. At night, the running lights will be a fuzzy glow. Then, suddenly, we will notice that the fuzziness on the wingtip has gone, with the running light bright and sharp, and if we look closely, we’ll notice that ice has stopped forming. We are still on instruments and in snow, but we’re on top of the lower deck and between layers. Staying here, we will not get any more ice, just snow, which doesn’t bother us, because we are not actually in a cloud. The air will generally be smooth. Occasionally, we may feel a slight bump, and looking out the window, we may see a slight fuzziness on the wings and realize we’ve picked up a little ice. What happened was that we went through a portion of cloud. In doing so, we probably encountered temperatures that were fairly close to the freezing point. This little cloud is just a piece floating around in a whole mess of temperature change and moisture, trying to form a large cloud mass, but it hasn’t quite got the right formula, so the water vapor turns directly into snow. The lower the air temperature, the truer this will be; that is, the colder the air, the less cloud. Thus we can form another rule that says, “If the temperatures are near freezing, warm fronts are dangerous things and should be considered very

carefully before being flown.” At higher levels in this vertical cross-section we may find another cloud deck; but it will be high, 14,000 feet or more, generally composed of ice crystals, and will have only light rime ice. If this deck has more than light ice, you are probably in the slope of the frontal surface. Go down to get back in the unclouded snow, or if the airplane climbs well, go up to where it’s too cold for much ice. This will be above 18,000 feet, perhaps 25,000 feet. It’s wise, also, to keep the surface and lower-level temperatures in mind, knowing that if they are a region of above-freezing temperatures, there will of course be no ice; and a place to escape. It’s pretty silly to sit up high fighting ice when one could be lower in above-freezing temperatures. Sometimes this other cloud deck actually doesn’t exist. I (RNB) remember one time flying in moderate snow at 8,000 feet, on instruments but not actually in a cloud. For curiosity’s sake I climbed on top. The top was 25,000 feet, and at that altitude there was only blue sky above. During the entire climb, the airplane never went through any actual cloud, but once on top and looking down, the stuff below seemed to be definite cloud, like the top of a stratocu deck. Descending back into it again, I saw it was only snow and haze, with no cloud and no ice. Now, as the frontal surface approaches, cloud becomes more frequent. If there is a top deck, it will eventually merge with the lower deck, resulting in a fairly thick cloud deck. Here is where the front becomes interesting, the ice problem is in that wall of cloud. The lower the temperature, the less ice; but just for meanness’ sake Nature fixed it so that we can get ice at pretty low temperatures. It’s the moisture content that really counts. In days past, we could have received that information from a meteorologist, who would take a look at the radiosonde observations, giving a pretty good idea of how much moisture there is aloft. Of course, as we’ve said, the chances are slim that we can talk to a meteorologist, so what then? It will be in the forecast, whether text or graphical, which will simply tell us where and at what altitude ice is expected. If there’s lots of moisture and conditions are right for ice, the forecast may call for severe icing. That’s the modern, computerized way of saying how much moisture is in the sky. It doesn’t give us a “feel” for it, and they may include a fanny-saving fudge factor to be conservative, but we cannot count on that. Anyway, it’s on the safe side, and if the forecast says ice, it will probably be there. Lastly, if we do have any interest with in-depth weather analysis, today’s computerized world gives us access to radiosonde data with the Skew-T log-P charts. That’s where we can find relationships of temperature and moisture helpful for predicting where enough moisture may exist for ice; however, it’s localized data for each location where the Skew-T log-P is located. Generally, the distance through this walled area isn’t very great, but it can be far enough to give a load of ice that’s very troublesome. The easy way is to go on top of it all, climbing until it’s CAVU above. Unfortunately, the tops of these

conditions are very high, in the area of 30,000–40,000 feet, where we obviously need a high-performance airplane. The more laborious way is to barge on and see what happens, but first the pilot should be pretty certain not to be flying along the front, instead through it via the shortest distance. We get this information from either the weather map before takeoff or onboard our aircraft through data link. Then we study the location of the fronts and the probable direction we’ll go through.

Fishing to Get Out of Ice In flying up to the front, we’ve stayed at a level that is pretty much cloud-free. That comes from old Rule Number One: do something about ice when it first forms. If we are flying in snow without ice and then ice suddenly forms, we start a fishing expedition by climbing if we’re at a low altitude, and perhaps descending if high, carefully watching the wings during the climb or descent until we’re out of cloud, noted by the lack of fuzziness. This climbing and descending will depend on the temperatures. If it’s very cold, it will only take a little altitude change to get out of the cloud, perhaps as little as 500 feet. As the temperature increases, that cloud will get thicker and perhaps run into thousands of feet. When we learned these things, and experimented with them, it was the era of DC-2s and DC-3s. There was very little ATC anywhere, so one could change altitude and fish up and down, sometimes only a few hundred feet or so, without asking for or getting a clearance, a happy time. Today, of course, we need ATC clearances before changing altitude, unless it’s an emergency, and then we must announce it as soon as possible. So now, back to the frontal surface. As it is reached, climbing or descending will be a waste of time, because things are pretty much total cloud, unless we know that there are above-freezing temperatures below. The pilot ought to know where the frontal surface is apt to be in order to avoid climbing or descending when it is useless to do so, and by the same token, not just sitting at one altitude in ice-producing cloud before getting to the front. All this again means a careful study of the weather map and weather reports before takeoff, then keeping updated in flight, so the pilot can decide where the front is, what its past movement has been, and where it will actually be when we finally get to it. Another way of telling when we reach the front is by the precipitation—it will probably increase considerably and the clouds will also be more turbulent. If the precipitation becomes heavier, the air rougher, and the cloud thicker, you have reached the front. Now it’s a question of going through and hoping it isn’t too far. The best out now (an out is something no sane aviator takes off without, having it carefully thought out before departure) is a 180° turn. We can poke on in there and start getting ice. We know what’s behind us and where to go in order to stay out of ice.

Now it’s a question of deciding how much ice we are willing to take on before turning around. This amount must be divided in half, because if we go in and then decide to turn around, we’ll have to go back through that much again. Most times it isn’t too far through, but it’s something that makes us sit on the edge of the seat. Once through, there will be an abrupt change of some sort, the turbulence will stop, the precipitation will let up, or we may break out between very definite layers, maybe even on top. Once a pilot feels they have crossed the front, it’s time to fish again for a top, a layer, or something ice-free.

Taking Off in a Front It can be dangerous to take off when a front is very close to the airport. We are apt to climb right into a mess that we don’t know much about. It’s best to wait until the front passes, then sneak up on it knowing a little about the stuff that defines its character.

Learning Time All this talk has been about fronts that have below-freezing temperatures throughout. In spring and fall, however, fronts have above-freezing temperatures in various places, and while this sometimes helps, sometimes it makes matters worse. If there are above-freezing temperatures in lower levels, it’s a good time to play a little. That way, we can descend and melt off the ice. It’s a good day to fly high and find out what makes up these fronts. Before takeoff, a close study of the weather maps, METARs, and icing forecasts will give us a good picture of what is happening and where we’ll find the above-freezing conditions. Now we can go play. However, above-freezing temperatures can also be dangerous. Suppose the overrunning air is above freezing and it’s overrunning below-freezing air. The precipitation will be rain, except in the lower levels. Then it will be freezing rain, and that’s nasty stuff.

Orographic Effect Again The thing that complicates all the frontal business is local-effect orographic lifting. With the extra help of air being lifted up mountain slopes by the wind, the air can hold lots more moisture. When air is lifted that way, it can produce severe icing at very low temperatures. Take a cold front over the Allegheny or Cascade mountains. It collects lots of extra moisture that is pushed up the windward side of the mountains. That means more ice. These orographic effects are peculiar to various regions, and unless we know the region, we must guard against them. This is where meteorological help comes

in, whether from asking a weather office or even local pilots about orographic effect. With no meteorologist or local pilot knowledge, we inspect the prospects on our own, using personal knowledge of meteorology and its basic rules: One, are there mountains to cross? Two, is the wind flowing up the mountainous terrain? Three, is the wind circulation coming from a source of moisture like the Pacific Ocean or Great Lakes, and even smaller bodies of water, such as Lake Champlain affects Burlington, Vermont? If all the answers are yes, we can be certain there will be lots of ice in the clouds and either be prepared to cope with it or sit on the ground. Always be extra cautious with ice and fronts when in mountainous terrain. If we’re in a part of the country that’s new to us, here’s where a broad look at a sectional chart can give us a feel for terrain and weather, as can a good chat with a local pilot.

Cold Front In flying fronts, the problems are pretty much the same whether the front is cold, warm, or occluded. A cold front is more violent, quicker to get through, rougher, and has more ice. The warm and occluded fronts are a little slower but cover a larger area and make you sweat longer. Ahead of a cold front there is a high deck, with some layers below, but it’s generally easy to maintain a position out of the clouds and, of course, out of the ice. As we fly into the front, ice will be plentiful. Cold fronts are unstable, with air being lifted quickly, and therefore carrying considerable moisture. Consequently, the ice can accumulate on the aircraft in heavy amounts and can do so quickly. However, the distance through this area is relatively short. The danger, or rather the mistake often made, in passing through a winter cold front is staying in the stratocu deck that forms behind it. The front itself may have been passed through, but the airplane remains on instruments, getting ice. Actually, a couple of thousand feet higher might put the airplane on top, in the clear. To avoid ice, cold fronts can be flown higher than warm fronts. We remember that the lower the temperature, the less potential there is for ice, so flying up high will help. Then, when the actual solid part of the front has been traversed, there’s a better chance that the airplane will be on top of that lower stratocu deck on the backside of the front. Flying weather of this type is like learning to play the piano. It takes time. A pilot must study the weather carefully and then begin crawling before walking. There are certain days when we can poke into these things, seeing what they are made of, and still leave an out or two. For example, when overrunning air causes an altostratus deck, the weather is simply high overcast, with the weather at the airport good. That’s the day to go on up there and poke into that altostratus, then fly a while toward the frontal surface, eventually turning around to return home

and mull it over. When any opportunity like that presents itself, we should use it as a valuable learning experience.

Flying to Feel Ice Let’s summarize a bad situation we have picked at throughout this chapter. We stayed in icing conditions too long, and the aircraft has too much ice. When ice begins to change the important aerodynamic shapes of our aircraft, it not only increases drag that affects things like stall speeds, but also influences the aircraft’s stability and control, as well as related handling characteristics. Because each ice experience can offer different changes to our aircraft’s shape, we are faced with an undefined variety of flying characteristics and handling. This issue leaves us in the dark as to what we can expect from our airplane, but we add speed to landing in hopes of counteracting poor stall characteristics or maybe use less landing flap to avoid stability and control issues. What else can we do or do we need to think about? First, it’s obvious that if we have a lot of ice, we have that undefined airfoil shape and all sorts of drag. Our airplane needs more power than available, and probably stalls at some lesser angle of attack with unknown characteristics, and very possibly before the stall warning will work. The airplane has to come down. If we keep enough speed, which really means keeping our angle of attack below that of stall, we can at least crash under control; if we break out of cloud with enough altitude to find a place to go. Grim prospect. Another consideration is that many icing accidents seem to occur in descents or landings. In these phases of flight, we’ll slow for a holding pattern, and eventually the landing itself. This means we are increasing our aircraft’s angle of attack, approaching that unknown stalling point. The airfoil change may also cause an asymmetrical stall, so the airplane will fall off on a wing, heading for a spin. Remembering the explanation of SLD icing, the aileron “snatch” is a result of too high an angle of attack. If we had been using flaps and then retracted them, the angle of attack will increase and possibly cause at least stall buffet, if not a total stall; if there’s time, we may be able to put the flaps back to where they were. In all these stall events the recovery is still the same; get the nose down and the airplane flying, but if we go off on a wing, we’re probably looking toward a spin recovery technique, hoping the ice-covered airplane will still respond as it would clean. Also, we hope we have enough altitude, as well as instrument flying ability, to do this on the gauges. Another event that is rare, but does occur, is stalling an iced up stabilizer. Usually this occurs with flap extension. With the horizontal stabilizer normally lifting downward, the flow off the flaps creates an angle-of-attack increase on the stabilizer’s top, it stalls, and pitches the aircraft down, usually quite violently. Low to the ground, the chance for recovery is slim. This stall is totally different,

requiring us to pull back on the control wheel or stick—often with very strong force—and immediately retract the flaps. Adding power is not always helpful, depending on an airplane’s power-pitch effects. If that solves the problem, leave the flaps up. This is a main reason we consider leaving flaps retracted for landing an iced-up airplane, especially light-to-medium general aviation designs. For more on this tail-icing issue, we again recommend NASA’s SLD and In-Flight Icing Training media, as referenced in the Suggested Reading section. Aileron snatch and tail stall aside, a more normal concern is flying in icing conditions with an autopilot. It can hide two important things. One is any major handling characteristic changes. The autopilot will mask these changes, or it will until the autopilot cannot handle any excessive control pressures, and then disconnects. At that point, the airplane is off and running, and we’re grabbing for controls that are racked to some limit; at the same time, the airplane may be off on some aerobatic event. And we are on instruments, where no autopilot, Flight Director, or guidance boxes will do us any good; we only have basic instrument indications and hand-flown response. If we hand-fly the airplane in ice, or at least off and on during cruise, we feel the airplane; both in handling as well as its stability and control tendencies. If our controls tell us of vibration or lightness in any axis, we need to define which controls and think accordingly. For example, ailerons may be an ice ridge problem, requiring us to keep that speed up for less of an angle of attack. Or a pitchy, light elevator that is hard to control and tends to pull forward may be warning of potential tail-stall issues; don’t put the flaps down for landing and keep the speed up. Overall, hand-flying lets us feel the whole airplane: Is it mushy, or does it yaw, or roll back and forth? Maybe it feels like we’re sitting on a greased flagpole, on a windy day, with springs tied to our rear ends. Sounds inappropriate, but when you’ve flown an airplane that feels like this, it’s a very graphic description of an uneasy condition. So if we have been flying in ice, it’s a good idea to hand-fly for at least occasional periods during cruise and initial descent, allowing us to feel any changes to our aircraft’s handling characteristics. However, when it comes to the later part of the descent and landing, it’s also a good idea to consider hand-flying the whole event, minimums weather allowing. And the same goes for takeoff into icing and the climb through it; if we really want to do so in the first place. Such is another reason to stay sharp with our hands and feet.

Coming Home We’ve flown through ice, made a letdown, and now have the runway in view. The flight is about over, and we’ve got it made. Well, we really haven’t, of course, because that runway may be contaminated with ice or various types of new or old snow cover, and maybe a gusty crosswind, too. Now what? First, we find out as

much as we can about the runway condition, especially braking reports. We define that in Chapter 19 , but let’s assume the braking is supposedly lousy. We’ll land short—or at least hit our touchdown spot and not float—in order to have as much runway as possible for braking, but not so short that we undershoot. It also is worth touching with a bit of firmness, especially if there is standing water to help prevent hydroplaning. If there’s a crosswind, we’ll use proper technique, including rolling into that upwind wing and making the same timely and concise rudder movements, as we did taking off on a slippery runway. Once on the ground, we want to try the brakes gingerly, feeling what’s there. This needs to happen early in the roll-out. Without an anti-skid brake system, as in most general aviation aircraft, the best braking comes from the on-and-off method talked about earlier. Larger aircraft that are equipped with anti-skid brakes allow us to push on the brakes and allow the system to take care of this off–on business automatically. Modern automobiles have anti-lock brakes, which, to a degree, are the same thing. The moral is don’t try to cycle the brakes, because it messes up the anti-skid, potentially making things worse. Just lean on the brakes, and if you feel and hear the “thump-thump-thump” of their cycling, stay on the brakes and let them do their thing. Really high-end aircraft have automatic braking that goes into action on touchdown and brings the airplane to a stop without the pilot doing a thing. There’s always a question about how far to go with aerodynamic braking; that is, using flaps during the landing roll or trying to keep the nose wheel up in the air and the tail down so that the entire airplane is creating drag and slowing down. This is worth investigating in our aircraft’s flight manual or fiddling with it on dry runway days. There is concern that not having the nose wheel on the ground and helping to stabilize the landing rollout, especially in a crosswind, makes things dicey. It’s a known, established fact that the fastest braking comes from wheels in contact with the ground. This means that one should get the nose wheel on the ground gently, and the airplane’s weight on the wheels, where the brakes can take over. Of course, if the aircraft has spoilers, especially jets, they need to be extended. Some like the idea of retracting the flaps to reduce lift, hence more weight on the wheels. The flap-retraction issue meets with serious debate, and frankly we feel is a bad idea on a retractable landing gear airplane; you guessed it, moving the wrong lever in the heat of battle. In fixed-gear airplanes, especially if that is all we fly, it may be worth considering, especially if a classic old-timer with quick-operating, manual flaps. Another benefit of flap retraction on contaminated runways, especially slushy ones, is protecting the flaps from stuff being thrown off the wheels and onto the flaps. And remember the appropriate braking technique. Lastly, this is usually not technique for higher end aircraft, especially large and turbine powered ones. If the runway is sheet ice, there may not be any brakes at all until one is moving quite slowly, and then braking will be marginal, at best. So it would seem

that aerodynamic braking would be best; that is, we should get as much as possible from it. But if a runway is that slick, then we really don’t have any business landing on it. We should go elsewhere, if possible. The facts say to get the weight on the wheels and get stopped, but there may be a few times when this won’t work. We cannot make a rule. This is where judgment backed with knowledge takes over. Pilots, hopefully, will always have to make judgments; it wouldn’t be a very interesting game if they didn’t. Of course, we must not forget the luxury of reversible thrust, whether jet or propeller, making a safe and graceful stop more likely. In the case of a jet, remember the reversers are most effective at higher speeds, so get them in action as soon as possible after touchdown and don’t be bashful with the thrust. However, in crosswinds, it is important to remember that crosswinds can make an aircraft laterally unstable, especially ones with tail-mounted engines. What happens is that some configurations of tail-mounted engines find the reverse thrust blanketing the fin and rudder, effectively reducing its size and stabilization. The crosswind starts us weather cocking, then the aft thrust vector also develops a side vector in same direction as the wind’s effect. Good old vector-analysis from math. Usually the solution is taking out the reverse thrust; if this is not done quickly, we’re very possibly going for a sideways ride down the runway. If we do get into one of these “excursions,” but through some fancy footwork get the old bird straightened out, we want to keep it straight from where we are on the runway, and not steer back to the centerline. That effort may set us off on another wild ride. Let’s say we are well slowed down on the runway and feeling pretty good about it. Now another little hazard creeps in: turning off the runway. It’s often tempting to turn off as soon as possible if there is landing traffic behind us that we don’t want to hold up. Too fast a turnoff on a slick surface may find us going sideways into a snow bank. One must proceed slowly on icy surfaces. Generally speaking, we may be rolling along at a faster rate than thought. The bigger and higher off the ground the aircraft, the more this effect occurs; thinking we’re only doing 20 miles per hour may actually be 40. We turn off the runway onto a taxi strip slowly, even if the tower is yelling at us to clear the runway; if runways are slick, then ATC had better give a little extra spacing between landing aircraft. Normally, however, they don’t, especially at bigger airports, so if on our landing roll the turn off looks dicey, especially if we’ll miss a taxiway they asked us to use, we need to let them know as soon as possible; that airplane on short final behind us will prefer a goaround at 300 feet, instead of 50 feet. As we park the airplane, it’s important to be certain the surface is not so slick that our airplane will start sliding after we’ve left it. Surprisingly, too, pilots sometimes hurt themselves when getting out of the airplane and setting foot on an icy surface. Our minds are apt to be full of reflection on the flight, and the landing

just made, so we are not mentally back to earth with enough sense to think about such details as ice on the ground. An undignified fall with a broken bone or two would be too bad, especially after flying safely through all that weather and ice!

17 Taking Off in Bad Weather Now let’s talk about the three parts of a weather flight: takeoff, en route, and landing. We have studied the weather in earlier chapters. We’ve made a flight plan, picked a surefire alternate, and decided on fuel. The airplane has been preflighted. It’s ice-free, and the pitot static ports are free of any obstructions. The charts we need, whether primary navigation or backup to electronic, should be arranged in order and placed where we can reach them easily in flight. Our portable electronic devices have been efficiently arranged, without wires hanging everywhere or blocking out the windshield. These portable devices, along with any programmable aircraft electronics, have been loaded with necessary information and carefully verified; if we have someone flying with us who is willing and capable, we can have them verify this data input is correct. We’ve studied our flight’s routings, including departure from the terminal, en route, and arrival at the destination. There’s a pad and paper handy, and perhaps a kneepad. If the airplane has an intercom system, we are wearing a headset with a boom mic. We do our normal checklist and again verify our navigation, and that each radio is set for the departure. If there’s an ASOS, AWOS, or ATIS, we’ve listened to it, set the altimeter, and brought pertinent information into our departure plans.

Altimeter Setting If there isn’t an ATIS or ASOS/AWOS, we try to get the wind and altimeter from any official source, otherwise as accurately as possible to the airport’s elevation at the point we’re located. Altimeter setting is very important and should be set before takeoff. If there is an official choice, we don’t just set the altimeter to the field elevation and think that’s okay; we prefer that official altimeter setting. This checks the altimeter’s accuracy by noting whether it reads the field elevation. If it doesn’t, then our altimeter’s accuracy is suspect, and we’d better dig deeper. First, get a repeat of the setting, and if that doesn’t correct the problem, it’s time to go back to the shop. If we are depending on VOR navigation, and there’s a VOR Test Signal (VOT) on the field, the ship’s receivers should be tested for accuracy. We want to make sure the GPS system has sufficient satellite coverage, accuracy, and a current data base. If we are using an ADF, we should be certain to check all its functions: antenna, manual loop, and pointing to the station when in automatic.

Be Prepared When we take off, especially at night or in instrument conditions, it is nice to have a navigation aid quickly available to aim us back toward the airport. In years past, when ADFs were still commonly used, unless part of the departure procedure we’d tune the ADF to the Nondirectional Beacon (NDB ) at the outer locator of the ILS runway being used for landing; assuming, of course, the airport had one. Or we could have something set up on the second VOR/ILS. Today, using GPS or IRU systems, it’s a “direct to” selection to find the airport, or an instrument approach is stored and ready for hasty return. All this is for an emergency situation, in case something serious happens right after takeoff, such as a fire or engine failure, and we want to quickly return. We would know which way to head while telling the tower we’re in an emergency and need immediate return. Unfortunately, the FAA is removing the NDBs, so no matter how diehard we may be on flying old-school, the end of most NDBs is on the horizon. And for all this, we have checked which runway and approach is being used for landing, as well as the approach’s inbound heading and altitudes. This is all planning for, we hope, a far-fetched possibility, but it’s this kind of detail that is part of aviation’s nitpicking. Like so much of this thinking and preparation, it may be rarely needed, but can make the difference between an interesting event versus an unfortunate one.

Let’s Go Now we start up, set up whatever is left in preparing our aircraft, and only then do we call for our airway clearance. Of course, we might want that airway clearance before start, if it will take time for the clearance to come through, or will cause the fiddling with route programming typical of electronic cockpits. When the ATC clearance comes through, be ready to copy it on a piece of paper—the kneepad again. Never leave it to memory, even though there are useful acronyms to help us make sure we have all that is required. After it’s copied, we read it back. After that’s done, let’s absorb the clearance. First, mentally picture the route. Be certain the avionics and navigation systems are set up and ready with the correct courses and modes of operation. Then, we firmly implant in our minds the altitudes and headings, as well as any unique departure procedures and initial selections needed for electronic navigation. There are a couple of benefits to getting our airway clearance before engine start. One reason is that electronic navigation, instrumentation, and aircraft preparation tends to keep our heads down in the cockpit, while programming and checking our clearance’s routing, which isn’t clever sitting on the ramp with an engine running; especially, if there is only one of us on board. A quiet aircraft lets us concentrate on all the clerical stuff without a nagging, running engine. Worse is

being rushed then taxiing the airplane while trying to do all this stuff. Nor do we want to set up an initial routing, betting on finishing the job once airborne. It is very important to understand the routing of our flight, whether using maps or electronically displayed routings. We want to know where we’re going and have our maps folded, marked, and in sequence. This is especially important when flying in unfamiliar areas. Once while a new and “adjusting” captain, the airline had sent me (ROB) to fly an intra-European trip, the routes recently acquired through a merger with another airline, and an area where I had never flown. We were leaving some place in Eastern Europe, where getting all the procedures and maps together was extensive; we were in a 727 with basic instruments, which was nothing more than any analog-instrumented light aircraft. On the taxi to takeoff, the departure procedure and initial routing still felt vague, despite earlier review, especially the navigational aids of mysterious names and location. Even though the copilot and flight engineer were more familiar with the area, it was important to have the whole crew on the same page, especially the one who gets yelled at if something goes wrong; the pilot in command. So, we pulled over on the ramp and reviewed the whole fandango one more time. To heck with schedule. So, after we have our clearance and everything is ready to go, it’s worth having a departure briefing; not a taxi or before-takeoff checklist, but a briefing that goes over key items affecting a departure. Years past, much of this kind of fell in with our before-takeoff thinking, but those simple days are gone; there is a lot of stuff to remember these days, and it is easily confused or missed. Some departure briefing items we like are below; obviously folks will hone them for their needs: • Weather: • Winds, temperature, and density altitude. • Takeoff and return landing minimums. • Sky—wind direction, shear, turbulence, and thunderstorms (radar use, deviations, should we takeoff). • Environmental—cold/icing or hot weather. • Taxi: • Review taxi route and congestion issues. • Runway: • Length, surface type and condition. • Slope and initial obstacles. • Terrain: • As effecting takeoff and climb to cruise. • Takeoff Procedure: • Initial turns, headings and altitudes. • Aircraft clean-up.

• Automation—when planned to engage and initial functions. • Abnormals: • Engine loss; • Return procedures and navigation; • Aborted takeoff criteria and procedures. The idea of the departure briefing, maybe at best a short but concise checklist, is to pull the whole takeoff and initial flying event into a homogenous package. The above example may seem lengthy, complex and time consuming, but like so many things, once it’s a habit, the process is much quicker. This departure briefing would best be reviewed before we start the engine/s and begin to taxi, if at all possible. Also, even though many of today’s aircraft, especially single-engine ones, are not intrinsically complex as just basic airplanes, we’ve made them so with all the electronic systems and ATC environment. For such aircraft, the days of “kick the tires and light the fires” are over.

Radio Thoughts Usually, we will change frequency after takeoff, so we want that set up beforehand. If we don’t have a dual frequency preselect on our radio, we need a firm note of this frequency; the best is to write it down as part of the clearance. Right after takeoff is a busy time, especially for a single pilot hand-flying IFR, and if we somehow miss that frequency selection, it’s a bad time to be chasing around for the correct one. Also, once in the air, when new communications frequencies are given, if we do not have those preselect radios, we should still write the frequencies down. In this way we’ll always have the last frequency. If we then call on the new frequency and there isn’t any response, we’ll know what frequency to go back to. There’s nothing more frustrating than tuning to a frequency, discovering it’s a dud, and then asking yourself, “What the devil was that frequency I just left?” We had to do this when I (ROB) started my career, and after a long flight you’d have 30 or more down the list, but this saved us from moments of wrong frequency or slipped numbers, more than just a few times. It’s an old technique, but not everyone has all the latest equipment. Once we do take off, if we have a choice, let’s not be hurried about changing to departure control, or talking with whomever we need to. Today, a tower will usually tell us when to switch frequencies. If for some reason the tower takes a long time in advising us, we should ask them before switching; they may have a plan for us based on the ever more complex ATC system. If for some reason the frequency switch is at our discretion, there’s a tendency for pilots to feel they must change as soon as the wheels leave the ground. Well, the most important thing right then isn’t departure control; it’s flying the airplane. Before changing frequencies and talking on the radio, let’s get squared away; power set, flaps and

gear cleaned up, electronics selected and aimed correctly, all settled in a peaceful climb. A copilot, of course, makes all this easier and faster. But always, as in everything we do, the first thing is to fly the airplane. Good use of radios will make frequency changes easy if we plan in advance; but we’re all human and occasionally dig ourselves a hole. What we do is have that preselect frequency selection, and/or two communications radios, with one set on the tower and the other on the departure control frequency, and so forth, throughout the flight. After takeoff, when they say to change to departure, simply flipping the control panel switch to the other radio gets it done with a minimum of distraction. When no one is home on the new frequency, we go back to the old one and tell them no one loves us on their new frequency. Every once in a while, after a really long day, we’ll screw up and tune the wrong window, then about the last digit of the number we’ll forget it—and also the frequency we were just talking on. Now we grab maps looking for ATC sectors or fiddle on an MFD screen; of course not paying attention to flying the airplane. It happens so easily … Taxi Time As we taxi towards our departure, we’ll eventually run through a checklist that reviews, among other things, the altimeters, flight instrument, and navigation aspects of the departure; extremely important items that aim us in the right direction and keep us from running into things. Call it part of a taxi-checklist, as was the case in more complex aircraft, or maybe it’s all part of the before-takeoff checklist for our personal airplane. We can do it while we’re taxing, but for a single pilot, if we can run through the list while the airplane is stopped, it’s a much better deal. Even in two-pilot operations we’d hold off when the taxi process was hectic. A technique for reading this checklist first came my (ROB) way from a superb mentor years back. Our checklist said: “altimeters/flight and navigation instruments.” Although we were supposed to say something like: “Set and crosschecked,” after quietly looking things over, instead he’d point at each respective instrument, selection window and radio, check it with the written clearance, and finally verbalize the correct setting; and end the process with the required correct checklist response. (Remember, everything we say in an airliner is recorded.) This would include: altimeters, initial altitude, departure control frequency, transponder code, initial heading, and initial course, as referencing from whatever instrument needle and radio. As we went from the analog simplicity to electric jets, we’d discuss what was going to happen with electronic mode selections and related navigation; and time proved this verbalizing, especially in the glass-cockpit world, is a needed standard. These are important checklist basics we deal with on departure, as well as other phases of flight, which allow one to verify not just an item, but by confirming that it was set and verified off written clearance. It also helps it sink into our minds. A lot to say for a checklist, but when the process is

habit, it doesn’t take long. Also, right after takeoff is not the time to be trying to read written clearance and fumbling with selecting a frequency or whatever, because it was not verified before departure. The taxi-checklist also covers certain system operations, such as the important flap and trim settings, as well as having things like the pitot heat on. As mentioned in another chapter, the pitot heat is important, especially in aircraft with EFIS equipment, and it could be critical to forget it. We also remember that some pitotheat systems are not approved operation while still on the ground, so we need a reminder, such as a “final items” checklist, that’s used just before we start our takeoff roll. Lastly, during the taxi, check to see that the DG, heading and attitude reference, as well as the turn indicator, are working and indicating turns in the proper direction. After the checklist we then mentally review the flying process we’ll follow during and after takeoff. This means visualizing the takeoff and departure, then making a quick review of the basic stuff like, “Lift off, up gear, climb at ____ indicated. Change to departure control. Up flaps at ____ speed (or before ____ maximum flap speed), set power. Right turn to one five zero. Level off at three thousand,” and so on. Here we have taken the data from the pragmatic taxi check, and brought it to life. The point is to mentally preplan, to know in advance. We don’t just fling ourselves into the air and then begin to think what to do. It’s all part of the important rule about flying; plan well ahead of the airplane.

Don’t Be Bashful! Of course, the tower, departure control, or en route ATC may suddenly change the routing or altitudes, and we have to be quick and flexible. Write it down and then visualize it; this, of course, is made easier if we’re looking at an MFD with graphical route display. Verify waypoints, route continuity, and so on. If there is the slightest doubt, ask ATC for clarification. Don’t be bashful! A neat cockpit with handy charts, whether for primary navigation or backup to electronic navigation, is also important. It makes it that much easier to look up some intersection, VOR, or waypoint that’s unknown to us. There isn’t anything wrong, either, with asking ATC where the heck the intersection or station is, especially if we’re trying to figure out some waypoint’s spelling that we’ll put into a digital navigation system. As mentioned earlier, if we can’t find it or make the assumption it’s spelled one way, but we’re wrong, that wrong direction turn, even for a short time, could spell big trouble in mountainous terrain or crowded airspace. High-profile and tragic accidents have been caused this way. When we use VOR as it used to be, each time we tune to a station we’ll use, we must be certain to identify the station’s Morse code identifier and to have the identification sink in; we should not just listen to random dots and dashes.

Embarrassing things have occurred due to a failure to identify, such as a pilot I (RNB) knew who tuned Orly Airport’s ILS in Paris, France, shot an approach to 300 feet, and landed, only to find he was at Le Bourget, all the way across the city to the north! He failed to identify the ILS. Sadly, things have happened with more serious consequences, so identification of any aid before use is very important. With modern GPS navigation systems, we can be so easily swayed that all the past is gone and forgotten, but if we use any part of older systems, then the past is still here. If we are flying an older instrument panel using VOR navigation and maps, it is very easy to become complacent about this, because the numbers on radio dials are clear, and there isn’t any fishing and tuning; we simply turn the dial to the number, and that should be the station. Mistakes can be made: we looked at the charts for a frequency and set it up, but in the chart confusion we read the frequency for a different station; frequencies are changed, and we may have missed the NOTAM that supersedes the map; or we may not have the latest chart revision in hand. Another one that will get us is an airport using the same frequency for opposing ILSs on the same runway, the only differentiation being a different identifier. If we just happen to be the lucky folks who show up when the landing direction is swapped, but the control tower forgot to swap the ILS frequency, it can turn into a real mess. We’ve had it happen, but fortunately the identification caught it. All these, and more, have caused wrong tuning and accidents. Even our home station, which we know so well and, perhaps, are looking at right over the nose, should be identified. It’s a habit, and once it’s ingrained, it isn’t a big deal. Altitudes are also tremendously important. When given an altitude clearance, we should write it down or place it on an altitude reminder. Having an altitude reminder with a warning sound alert is very advantageous. We get the warning approaching and leaving the altitude, so this helps when the altitude is approached, or if we wander off a selected altitude. These are good gadgets, but the pilot still should keep altitudes firmly in mind and not count on the gadget alone to do the job. If we are low-tech, there are altitude reminders with numbers we can set, mounted on the control wheel or instrument panel. It’s a substitute for writing them down—a good one, too. One technique that came about was pointing at the selection just made and saying it out loud. Whether altitude, heading, course, speed, or whatever, the idea is to force us away from the habit of just setting something without thinking; instead, we take a second look and think about what we’re selecting, and what will happen next in flying to it. Although designed for two-pilot cockpits, it isn’t a bad idea when flying single-pilot, aiding awareness of what we are doing. One day years back, in a Cessna 182, while weaving through a VOR approach into Montpelier, Vermont, I (ROB) took to verbalizing the headings, altitudes, and letdown points. It seemed a good idea as the approach progressed through the

procedure turn, then down between hills that were still hidden by cloud. My companion was a nonpilot, on kind of a first date. Out of the corner of my eye, I saw her staring at the nut who was flying her through the clouds and talking to himself. Even when explaining the reason she seemed skeptical, but the approach had successfully threaded us between the hills, and that’s all that counted. Just about all aircraft have Mode C transponders, and now Mode S, that read altitude. The later Mode S also gets involved with more data, collision avoidance devices, and the oncoming, at this writing, ADS-B Next Generation air traffic system. With a transponder’s altitude reporting capability, ATC can catch any diversion, but obviously the idea is to paying attention to altitudes and not counting on our Mode C or S, and ATC’s watching altitude for us. However, checking altitude and the Mode C gives the redundancy desired in all flying, especially if we are a single-pilot operation. Another aspect of altitude-reporting transponders is when we fly above 18,000 feet in the United States, and varied altitudes in other country’s operations. Above these altitudes, we set our altimeters to standard: 29.92 in. hg. or 1013.2 hectopascals. Then, below these transition altitudes we set the appropriate altimeter setting. If we don’t, we’ll fly the previous altimeter setting and level off erroneously. For example, the difference between 29.92 and 30.22 is 300 feet. That’s not good; we probably won’t hit anything, but we are getting into violation territory. The words you hate to hear from ATC are: “Say your altitude.” Busted. One should anticipate altitudes. If, for example, we’re cleared down to 6,000 feet, we ought to be thinking, at 7,000 feet, “I’m leaving seven; remember, level off at six.” In other words, climbing or descending, be at least 1,000 feet ahead of the airplane. If it’s a fast jet descent, be 5,000 feet ahead. In the airline, we had to verbally say “passing 7,000 for 6,000.” Pedantic, maybe, but history has proven such is a valid task. When ATC clears us to a new altitude, we should get right at it and leave the present altitude as soon as possible, unless, of course, ATC says we can leave at our own discretion. This is important, because if the cleared pilot fiddles along for some time, or makes a little halfhearted effort at some minuscule rate that vacillates between 100 fpm and 300 fpm, it can create a real traffic conflict, especially in busy airspace. It’s important to get at it, right away. When we fly with a Traffic Collision Avoidance System (TCAS ), it is a creepy feeling seeing an airplane slowly changing an altitude, knowing the altitude change they were supposed to be leaving is where we are going, or may be a crossing traffic issue. In summation, when cleared, one should descend, climb, turn, slow down, or speed up smoothly but promptly. If for some reason we can’t, such as when we are waiting for our aircraft to reduce speed when given a speed reduction, ATC should be informed.

Off We Go

The tower clears us on to the runway, either for “line-up and wait” or “cleared for takeoff,” and we swing into position. As we do, it’s time for what some call “the final items,” relating to where the airplane is supposed to go: heading, altitude, and airspeed. These items climb and guide our airplane safely through the critical takeoff and early departure event. These little memory calls not only refreshes our minds on these important items, we physically and visually should check that flight-guidance systems have them set in place: altitude warning window, heading bug on an HSI, and airspeed selected, if the parameter is used. This is very important with the flight guidance systems integrated into today’s aircraft. Without proper programming when we takeoff, things can come unglued pretty quickly, especially if one tries to engage the autopilot at low altitude; if things are not correctly set, it’s going to take you for a ride. At that point, we either have a quick electronic fix, or need to disconnect the autopilot and hand-fly through screwed-up flight guidance indications, remember the heading, altitude, and airspeeds, make sure the airplane is cleaned up, and talk to ATC, as well as select and respond to further clearances; like it used to be done! Later, at prudent altitude and moment, we fiddle with sorting everything out and trying to engage the autopilot. If we are departing into low ceilings, we hesitate a moment and let good old mechanical gyros settle on the runway heading, and with an old DG, we reset the heading. We’ll check the wet compass, too, but no matter our instrument system, even the newest slaved electronic ones, we’ll see if they agree with the runway heading. (This is a good check when landing, too, being certain you’re headed for the correct runway.) If the time from startup to takeoff is short, and especially if it’s a cold day, we may have to delay the takeoff in the run up area for five to 10 minutes, making sure all the gyros are up to speed. If it’s night, we should be certain the cockpit lights are set to the most comfortable level, and that our eyes have acclimated to them. As we start the takeoff, we’ll make a last-minute check of the few items some call the “killer” items. The regular checklist should have prepared us well, but it doesn’t hurt to have a few, most important items that can be checked almost in one glance. The last check in most all airplanes—from light single to jet, takes a second or two and really isn’t any different; fuel quantity, pumps on, flaps at takeoff, trim set, spoilers down, heading in agreement with runway; for a general aviation aircraft we may add carburetor heat off, prop low pitch, pitot heat on. Maybe a bit different for a Cub at a country airport, but not much. It’s a habit that ensures us things that cause serious flying problems are set okay.

In the Stuff Quick We should have in mind that once we lift the nose and leave the ground, we’ll be

on instruments. It’s no time to worry about flying VFR first and then transitioning to instruments; be ready at once to be on solid instruments. If there’s good ceiling and visibility, then, of course, we want to keep an eye out for traffic, but let’s suppose the ceiling is low, 200 feet or less. Also, most night departures, low ceiling or not, require reference to instruments more than an outside horizon that’s poorly defined, if at all. Going on instruments means going to attitude flying immediately; it means looking at the artificial horizon. With the ADI pitch bar set on the appropriate nose-up attitude, at takeoff or climb power for our aircraft, we must be going up. One should know the pitch attitude for the aircraft at initial climb out and all the normal phases of flight, then fly them on the artificial horizon as needed. This is also useful if, for some reason, airspeed indication is lost or obviously erroneous. So that’s the first step: fly attitude. If the wings are level, we are going straight, and if one is down, we are turning, unless we’re handling the rudder like a new student, which we shouldn’t be. So the position of the wings on the artificial horizon is the other thing we look at. With wings level and the nose where it produces climb, we are on a straight course and climbing. It’s really very simple. If we have to turn, we lower a wing: 30° is enough. ATC doesn’t expect more, and making a steeper turn means more up-elevator and more concentration that may divert you from other tasks. Keep it simple. We first set the attitudes we want and then cross-check the airspeed, heading, vertical speed, and altimeter. Close to the ground, the pressure instruments briefly give erroneous readings. On some clear day, watch the vertical speed and altimeter just as you lift off. Chances are the vertical speed will show a descent and the altimeter will start down until you are 50 feet or so above the ground. Airflow over static ports is getting organized, initially giving this descending input. Once away from the ground, the pressure instruments settle down, but even then attitude is the primary guidance and the other instruments a crosscheck. This cross-check is frequent, however, as part of our constant scanning process. There is an interesting instrument flying takeoff story we thought you might like. Ted Hereford, a TWA captain who mentored your first author, was taking off from St. Louis one night, in a DC-2, during the mid-1930s. St. Louis weather was low and lousy. His destination, Indianapolis, was clear—thank goodness. Not long after takeoff, every flight instrument went dead, except the turn and bank. No airspeed, altimeter, rate of climb, or artificial horizon, just needle-ball. It was not good weather for a return to St. Louis, and Ted knew the cloud tops were around 4,000 feet. He kept the airplane straight with the turn and bank, then, by recalling the sound of the RPM appropriate for the two-speed propellers, Ted knew he was in climb. Once on top, he set the props and their sound for level, flew until it

cleared, then landed safely at Indianapolis, in VFR conditions. The combination of instruments that failed didn’t make any sense, and TWA could never duplicate the problem. But you could still see the twinkle in Ted’s eyes, at 95 years old, when he told me the story in 2001; he was sharp as a tack. Ted’s flown west, and we sure miss him, as well as his kind, but hopefully folks like Ted inspire us to really learn how to fly.

How about the Weather? We are off and away, but so far we’ve talked about flying the airplane; so let’s go back now and talk about the weather part of the takeoff. Before takeoff, if we think it’s cold enough for ice, we should have the propellers slicked up with fluid or hot from electric heating. The pitot heat is on, as mentioned earlier. If we are flying a jet, engine anti-ice is on, even if the ice may be in a stratocu deck a few thousand feet above. This takes away something we’d otherwise have to fiddle with in climb, or maybe forget if we get busy. With piston engines, we’ll clean out the carburetors with heat just before takeoff and then remove the heat as we start to roll. But once in the air, we must watch for engine icing conditions. Before takeoff, we check the wind direction and velocity. We’re learning about any crosswind and planning our takeoff compensation. The wind velocity says not only how fast we’ll get in the air, but if it’s gusty, it tells us whether we can expect turbulence once we’re airborne. This also makes us think about the wind just above the ground, reminding us of any shear possibility. The runway surface is of interest. If it’s winter, and the runway is covered with standing water, snow, ice, or slush, our ability to stop if the takeoff is aborted will be reduced, sometimes drastically. The V1 speed is out the window if the runway’s slippery. V1 is our takeoff “go–no go” safety speed, mostly used with multiengine aircraft, but a concept worth thinking about, even if not of formal calculation, when considering an abort of any takeoff. One airline criterion restricts takeoff to standing water, slush, and wet snow no deeper than ½ inch, and four inches or less for dry snow. Dry snow is such when the temperature is equal to or less than 30 degrees F/ −1 degree C. “Wet snow” is obviously above that temperature, and can be darn near like ice. Another way to unscientifically judge snow is if we can make a nice firm snowball, it’s wet snow. On larger aircraft with the data published, we need to recalculate our takeoff distances required, making sure we have enough runway. With light aircraft at small airports, the concept is the same. Without published runway contamination data, however, we should leave a healthy margin: 100 percent of minimum, if we can. The combination of a strong crosswind and icy runway calls for care in taking off. Until enough airspeed is obtained to give rudder response, we’re dependent

on nose wheel or tail wheel steering. Neither has much traction on ice, so the beginning of the takeoff is a little dicey. This can be an anxious moment, but things can be improved by lining up on the runway before starting the takeoff. Swinging onto an icy runway on a running takeoff is an almost sure way to be partially out of control right from the start. Getting lined up, stopped, and all squared away before starting to roll is the way to do it. Don’t let the tower push you into a quick takeoff just because they are trying to move traffic faster. Any takeoff, even in very reduced visibility, is started visually. We need something to grasp with our eyes. If the visibility is ¼ mile or less, we need a good centerline stripe or, better, centerline lights. Without these, the visibility must be sufficient to see the runway far enough ahead for guidance. In the commercial aviation world, their takeoff minimums vary depending on the lights and markings of runways; and as mentioned before, that’s something worth considering when flying under FAR 91, where we can blast off into extremely compromising conditions.

Once in the Air We need to keep the runway heading, or track, if required by procedure and available through advanced flight systems, well in mind, and once in the air, fly that heading until a turn is required. Both landing and taking off in snow, we find the air choppy and turbulent for approximately the first 1,000 feet. This is almost always true in snow, because of an unstable condition caused by the release of heat during nature’s snowmaking process. It isn’t dangerous turbulence, but it makes an instrument approach or a precise departure procedure more difficult.

Thunderstorms Again In summer, with thunderstorms in the area, we think in other ways. Thunderstorms mean turbulence and the possibility of sudden wind shifts. They mean heavy precipitation, downdrafts, and shear. All this during takeoff, at low speeds and close to the ground, makes us quite vulnerable. If storms are very close, it’s best to sit on the ground until we have some maneuvering room to take off, clean up the airplane and get organized in climb, and then deviate around the storms. When we take off with thunderstorms in the area, these are some things to think about: If we have airborne radar equipment, it should be warmed up and ready for action. With NEXRAD and/or a lightning detection system, before takeoff, we can inspect the entire area for thunderstorms, developing our plan to avoid the area. Most airborne radar equipment has a “standby” position in which the equipment is ready to go but isn’t actually putting out signals until the control

is flipped to an “on” position; that’s when the antenna begins to search and the screen lights up. We don’t want it on in the ramp area, where fueling equipment, people, or other airplanes are nearby, as the radar signal is potent enough to cause issues. Fiddling with airborne radar right after takeoff is not the best idea, as our attention must be centered on the flying business. Takeoff and early climb demand a pilot’s primary care, so we want to analyze the radar before takeoff, then leave it be until things are settled down and we have time to fiddle with tilt, range, and interpretation of the radar data. A good place to park an airborne-radar’s tilt control, after ground interrogation but before takeoff, is +5°; it’s a good angle for the radar to start searching at low altitude, when, just after takeoff, we have little time to adjust it. This discipline applies to any weather-avoidance device. A two-pilot operation helps, obviously, with the nonflying pilot taking on the task of radar guru. Such a comment seems sarcastic, but the point is that proper understanding and use of radar is really a practiced art. If we’re lucky to be flying an aircraft with the radar data displayed on the PFD or next-door MFD, it’s an easy display to read, while still flying the airplane. As we look at radar before takeoff, we’ll often see an escape route around thunderstorms that is different from where the normal departure takes us. We should have a chat with the tower before takeoff, negotiating our needed path. It’s so much more relaxed to do these things on the ground, than in the air while trying to fly on instruments. While we are ducking thunderstorm cells, ATC has to be kept advised and give us advance permission for deviations, so we don’t create an air traffic conflict. This is especially true in a terminal area, where traffic separation can be tight. On takeoff, when considering how close the thunderstorms might be, we have to think about the wind, as we could fly into a hefty, gusty wind shift with shear and downbursts. Suppose we are taking off south into a strong wind. A thunderstorm arrives and snaps the wind to northwest; our takeoff run is lengthened, and once in the air, if we get there, we’ll probably be in downdrafts that will make the climb sluggish at best and more likely dangerous. It’s a silly time to be taking off, of course, but sometimes it is difficult to tell just where the thunderstorms are, if they are hidden in lower clouds. However, we shouldn’t be taking off or landing with a thunderstorm any closer to the airport than our rules for normal avoidance in the air. They were 10 miles minimum, and 20 is better. Right after takeoff, the airplane is in poor condition, accelerating from slow speed after takeoff all the way through initial climb; a strong shear during this regime of flight is indeed dangerous, being at best difficult to cope with, or altogether impossible. Once in the air, we may get some pretty wild turbulence. We want a good workable airspeed as soon as possible, but of course, we don’t want to shove the nose down and fly into the ground. It all takes care and judgment.

We should have in mind a direction to run away from the storms if things get too tough. This refers to an area farther than the terminal area, more so as we work toward the route of our flight. This knowledge comes from a careful study of the weather before takeoff, in order to know how the weather is moving. In the past, we would study the sequence reports for stations in the area, in a 100-mile circle at least, as well as radar summary charts, to see what was actually happening. Today, we can look at NEXRAD, even on a personal electronic device, but also remembering that once we leave aviation weather information, it’s theoretically not official, and we need be careful of the weather information source’s currency. This thunderstorm weather is tough, and it shouldn’t be taken lightly.

Thinking Now we are in the air on instruments, encased in the tiny world of our airplane, everything outside ending at the windshield. Let’s not worry about relating ourselves to the outside, trying to see out there or holding on to that world we left. It’s best to forget it, settle down, and watch the instruments. We concentrate on the rather simple job of flying instruments. It is simpler the more we relax. Lack of worry makes us relaxed, while uncertainty makes us worry, so let’s not be uncertain; let’s know what we are going to do next, be prepared, and plan ahead. Our thinking is in layers. The top layer is flying instruments. But this is easy and doesn’t require much of our thought. If we’ve practiced enough, it’s almost automatic. The second layer is the airplane. Are we doing the right things to keep it running? Carburetor or engine heat? Power settings, pitot heat on? Fuel on proper tank, the gear and flaps cleaned up? In other words, all the things that will ensure the airplane is managed as it should be. If this orchestration stops, so does the flight, which isn’t a healthy option. The third layer is navigation. What’s the course we are trying to follow? Is the station identified, if we’re flying a good old VOR, or is our navigation and autopilot properly selected and captured, if we have technically advanced system? What’s the altitude? Are we level or approaching it? That intersection coming up, are we tuned, identified, programmed, armed, or whatever to have our airplane properly follow the route? We review all the items that are a part of our navigation, including flying that heading ATC may have given us. Layer four is the weather. Turbulent? Fly turbulence methods. Ice? Is all the anti-icing or deicing equipment being used, and what does the clearance ahead do for getting out of the ice? Thunderstorms? Are we ready for turbulence, is the radar or lightning detection equipment working, and do we know a way out if we want to run?

Layer five is a quick thought toward emergencies. If we want to return, how will we do it? If we cannot return to our takeoff airport, where’s the nearest place we can get into? These layers of function are not precise, nor are all the items listed, but the thoughts for building your own are there. The layers intermix at times, but once we get the airplane and engines set, we don’t have to constantly think about each thing. If the weather equipment is on and working, allowing us to plan far ahead, this makes the weather issue a source of referenced information, not constant concern. Emergency action, once it’s implanted in our mind, doesn’t require attention; it’s there if we need it. Each layer has a priority based on how often we need to refer back to it. As we navigate or follow radar vectors, it’s wise to visualize where we are and what’s under us. We shouldn’t concentrate on this to the extent of neglecting anything else, but it is particularly important in connection with terrain height. How high is the terrain and are we clearing it with enough margin? The charts and routings give minimum altitudes, and we should pay attention to them. This is a part of preplanning, having a good idea before takeoff of where things stick up, be they TV towers or mountains. All the fancy equipment and radar vectors should keep us above the terrain, but in the final analysis, missing the ground is our responsibility. In the back of our minds should be an awareness of what a topographic map of the region looks like, especially the heights of terrain, and then what our actual altitude is; this is now referred to as situational awareness . Before we had the many electronic devices that give us navigation displayed over electronically created terrain, and ATC to lead us around, it was prudent to have a sectional chart along, even if we were on instruments, navigating with an airway chart. The airway chart, at best, has a few higher obstacles, rivers, lakes, and airports, but if we had a serious problem, such as an engine quit or smoke in the cockpit and so forth, having terrain, geographical, and aeronautical data right in your hand could save the day. Even today, if our technically advanced instrumentation runs out of electrons, and despite possibly having a backup handheld electronic device, just having a sectional tucked down between the seats, folded along our route, isn’t going to hurt, and it may really help someday. Maybe a pedantically old-fashioned rant, but that’s our story, and we’re sticking to it. A good friend of mine (ROB) recently took a check ride with his light twin, which is all decked out with an EFIS system, technically advanced navigation, airborne radar, NEXRAD, lightning detection, you name it. The first thing he did on his check ride was open a sectional chart, fold it along the route of flight, and slip it innocuously between the seats. His instructor lit up and smiled like a little kid at Christmas, exclaiming: “I ought to pass you right here and now!” Radar vectors for departure, en route, or landing, and the altitudes the person on the ground provides, are supposed to keep us from hitting anything. Don’t

count on them 100 percent. Although truly professional and caring of their responsibility, no one is 100 percent perfect, and neither are we. There have been accidents relating to bad vectors, a mistaken altitude call, and so forth. Like a good crew relationship in a multiple-pilot aircraft, we can work the concept with ATC and vice versa, which they usually do. Very few incidents have occurred, but it has happened. When we fly, we’re all interestingly diverse humans, functioning in an inhuman setting. In the final summing up, the person flying the airplane is responsible for it, and missing the ground is a paramount part of the job. In today’s busy air traffic and regulatory aviation world, ATC folks and pilots alike are constantly being tugged from aviation’s once simple concepts. However, the ultimate responsibility is still the pilot’s. Never take anything for granted, and especially not the idea that a certain heading and altitude given from the ground will clear all obstructions. This is not always related to just the ATC clearance. For example, a standard instrument departure we may be flying in a mountainous area may not give us safe altitude clearance if the aircraft’s climb performance is lower than required, due to ice, turbulence, wind flowing down mountain slopes reducing our climb, density altitude issues, and so forth. It’s important to look over the departure carefully in regard to terrain and not just assume that it’s okay, instead relating to the departure route versus your airplane’s climb ability. This is published to a certain point on departure procedures, but eventually we’re out of the area and possibly still trying to reach minimum en route altitudes with these compromising conditions. We must, by any means possible, keep up-to-date on where we are. We must not simply sit there, wandering hither and yon, following the vectors, and not knowing where we are in relation to terrain. The controller may be giving headings, but the pilot is responsible for the navigation. Navigation is made up of many things, and one of the biggest is keeping position information and knowing where we are. A heading is simply directional information. Where the aircraft is and keeping it clear of all terrain is always the responsibility of the pilot in command.

18 Weather Flying En Route Now we level off at cruising altitude; sit back, and relax a little. The intense concentration of an instrument departure is over. This is the time to look around the airplane, checking that all is in order. We glance at all our systems; especially things like the fuel setup, making sure things are functioning as needed, such as pitot heat, engine heat, and deicing equipment. It’s a good idea to start on one side of the flight deck and cover everything to the other side, going across the instrument panels, and occasionally taking a peek at those obscure places, like hidden circuit breakers. If we are navigating with charts, they and numerous papers from takeoff preparation and event are probably mixed up, and this is a good time to get them organized and neat. The same goes for those charts we had between the seats, ready for backup if we are using electronically displayed navigation. Now there is an opportunity for writing down the takeoff time and the time a fuel tank was switched on as well as the other bookkeeping jobs. Knowing when fuel tanks were turned on, takeoff time, and maybe even with EFIS systems, some reference to time over checkpoints, is important. If we are flying with older instrumentation and maps, doing so is obvious and necessary, but why with EFIS? Again, if the electronics have a problem, we know how far along we are and where to start looking if we’re back to the basics. A lot of this theory is based on redundancy of aircraft. Admittedly, some of the higherend equipment is so redundant it’s right up there with high-end turbine aircraft, and it’s hard to imagine total failure with nothing from which we can navigate. However, in the airline, on those highly redundant airplanes, we still kept a “howgoes-it” log, at the side of the flight plan, comparing each checkpoint passed with estimated time as well as planned fuel versus actual. With all the snazzy electronic flight-planning systems out there, we can make up some pretty good flight plans, from which we can easily keep track of time and fuel. Or, if we want to exercise our neurons, we can get out a whiz wheel and figure one out. Either way, whether we do this paper and pencil or by following electronically, we need to keep track of time and fuel and whether we are running over or under our targets. As to navigation on cross country flights, we always want some basic reference to course headings, as corrected for the day’s winds aloft. A well planned flight log, which we update with actual time and heading reference, can easily present this information. The obvious reason is incase our electronic navigation has a problem, we have something to work with, especially if IFR

and/or night. Even flying highly redundant jet airliners over the ocean, with multiple IRU/GPS systems, the flight plan had a little chart that gave checkpoint, true heading, variation, magnetic heading, and wind correction angle based on forecast wind. It was rare odds that we’d be down to wet compass and who knows what, but that’s the way this business is; we plan for the lowest common denominator from which we can get down safely. We don’t know if anyone has ever had to use this information, but for kicks you could watch the course and wind data; it was very accurate. All that aircraft-transmitted weather data helps provide good wind forecasting. By the way, the gadget used for that is called an Aircraft Communications Addressing and Reporting System (ACARS). During all this, of course, we’ve been watching the weather. En route it’s a clear-cut problem of being, or not being, in an area of instrument flying, with possible ice or thunderstorms. Turbulence can be mixed with either. Turbulence is natural around thunderstorms, but if it’s rough in an icing area, the ice will be forming fast and heavy, with our problem being the need to get an ATC clearance out of there. Such a situation generally means unstable clouds, and up is often a good way out. The clouds, probably embedded cumulus in a general overcast, will occasionally be visible as we bounce in and out of them between layers.

Think Ahead We’ve talked before of the different weather conditions and how to cope with them, but here we should talk about what to think about while flying from one place to another. Of course, we are navigating, listening to the radio, working ATC, and keeping track of ground speed and fuel usage. We need to know if we’ll not only make it to where we want to go, but with enough fuel remaining if it becomes necessary for a diversion to our alternate. As we do this, our background thinking is doing the important job of keeping ahead of the airplane. This is a tremendously important part of flying, in or out of weather, but especially in weather. What do we mean by keeping ahead? We have the charts for the next leg of the trip in hand. As we fly toward one VOR or waypoint, we have the new course well in mind before ever getting to the station. If our route is electronically displayed, does it go where it’s supposed to and connect to the next waypoint? We are mentally prepared for a number of courses ahead. We have the terrain and altitude clearance well in mind, too. No matter if we’re using VOR navigation with maps or Area Navigation (RNAV) with GPS routing displayed in front of us, we should be anticipating well ahead of our route and airplane. If we are running separate fuel tanks, we need to know when the one we are on is due to run out. This means we’ll be calculating fuel flow versus tank quantity, then noting the time of each tank’s depletion, as a reminder so we can switch tanks before the one in use runs dry.

Other than good basic flying and operation of our aircraft, the most important task is tracking the weather. We keep up with weather sequences for our route, destination, and alternate. It takes more than one hour’s weather watching to catch the trend, seeing if it’s doing what was forecast. If it isn’t, then what does it seem to be doing? Is it getting worse or better? So we copy weather each hour and compare it with the last hour. It’s wise, as we fly, to listen in on Flight Watch. Hearing weather broadcast to others, PIREPs, and requests can give us an idea of what’s going on with many aspects of the weather. By listening to other pilot voices, one can pick up a feeling of urgency or tension in the back-and-forth conversations alluding to the weather turning sour or not acting as forecast. We can also learn a lot of what’s going on while paying attention to the ATC frequency we are on, whether we’re on an IFR flight plan or using Flight Following while VFR. And we can always ask what’s going on ahead of us. Better weather, of course, isn’t a problem. Worse means we have to plan for alternate action. What might that be? First, we should check deteriorating weather against the weather at our alternate. Is the weather holding? Can we feel confident that it is still a safe place to go, if we cannot get in at our destination? If it is, we keep going to our destination, make an approach, and if we can’t get in, proceed to the alternate—just like the book says. If the alternate is also going down, then we need a new alternate. If our study of the big picture was complete before takeoff, any change from the forecast should be understandable. We should be well equipped to take action. A good weather pilot has this secondary action in mind well before takeoff, action that fits the day’s weather setup. Again and again, knowing the big picture is imperative! Being ahead of the airplane means having early plans to handle unexpected situations. Not being ahead means being the person who faces a changed situation unprepared, in a panic mode, unsure of what to do next.

What’s It Like? What’s it like en route, as far as our flying condition is concerned? Well, we are either on instruments or not. We can be under clouds, on top of clouds, or between layers. We can be in and out of clouds. Piston-engine airplanes, especially if they are not turbocharged, will be in cloud more than any other type, but even so, most “instrument” flights will be between layers or on top. Clouds rarely stack up from the ground to some great altitude. When they do, it is in a front or near the low center. These are not far across, nor do they stay in one condition for long periods. A big portion of weather flying occurs in postfrontal conditions, and that means flying on top. Prefrontal conditions will be largely under an overcast that may gradually squeeze down on us. What we are saying is that most instrument flight isn’t on instruments. When it

is, it’s because we are flying in a front or low, as we said, or we’ve made a bad choice of altitude—like being in a stratocu deck when we could be on top of it. This allows us to sum up and list the conditions. We’ve said we’ll very often be either on top, under, or between clouds. In these conditions, we are staying out of ice and are able to see thunderstorms, making it easy to avoid them. When the clouds get together, we can get ice or fly into a thunderstorm. We are near the frontal surface. If we aren’t, then we’ve just slipped into clouds that are higher or lower than the ones we’ve been flying over, under, or between. If we understand the weather situation, then we should know if it is best to go up or down. Should the clouds have enveloped us, and we’re near the front, then perhaps it’s time for ice. This isn’t a reason to feel all is lost. Many times there are abovefreezing temperatures at a lower level. Then it’s simply a matter of getting a clearance to go lower, remembering terrain clearance. If the temperature is below freezing all the way to the ground, then the job is to be certain we are above the lower stratus clouds. This means a higher altitude. But in getting this higher altitude, we are not trying to get on top; we are just fishing for an area where there’s little or no cloud; it will probably just be snowing. We can pick the altitude above the lower stratus clouds and go into the front knowing we’ll very likely run into higher cloud, where we’ll get ice. If we do, and remembering the temperatures are below freezing all the way to the ground, the only sure way out is turning around, we must not dally in these conditions. Doing so risks going in so far that we cannot safely turn around and get out. If we are crossing the frontal surface at right angles, it shouldn’t be too far through, so let’s be certain we are crossing it the fastest way. If we fly along the front, then we’ll really ice up. We have talked about thunderstorms earlier in the book. We recall they are either air-mass types that allow us to wander around them, or they are frontal, and we are on instruments, probably near the storms and needing radar. Without radar or lightning detection, we have no business being in there! If the radar breaks down once we’re in the weather and playing hide-and-seek with thunderstorms, we need to be prepared for a rough ride. This points out that we shouldn’t fly fronts—winter or summer—until we have a lot of instrument experience. So en route, we watch weather at our destination and alternate, but we also watch to see if any fronts are getting in the way of our route. Generally, precipitation and easterly winds make us suspicious of a warm front. Out there somewhere is the frontal surface, where the winds go from easterly to southwest. Ahead of that is the large area of precipitation. That’s where the weather is and where we’ll find embedded thunderstorms in the summer, and sometimes in winter, too. In the winter, we’ll find snow, and in a more or less narrow band, we’ll find freezing rain. Until we’re experienced, we simply run away from this area, either by making an end run, if we have a long flight and this is even

possible, or by landing and waiting it out. We pick up a cold front more easily, because its wind shift is more dramatic. It swings from southwest to northwest, with heavy rain, thunderstorms, or heavy snow and snow showers. It’s rough in summer or winter, with ice in winter, thunderstorms in summer. Are you equipped to take it on? Equipped in skill and knowledge and airplane and gadgets? If we have been flying on autopilot, should it fail in the middle of the front, can we successfully hand-fly through the rest of the weather? No, not by depending on a ballistic chute, but hand-flying a perfectly good airplane. If not, we beat a retreat and wait for it to go by. Flying en route is a crafty time. We watch the weather; how is it doing for our destination and alternate, as well as developments along the way, deciding if they mean something different, that something is on the move—again, the big picture. Watch the ground speed and its relationship to fuel and distance. These, together and interrelated, are the budget, and we cannot afford to overspend.

Forced Landing with Little Time to See Suppose we are faced with a forced landing while flying on instruments, especially if the weather is low, meaning there will not be much time from when we break out of clouds until we’re on the ground. What then? The first thing is fly the airplane, then take care of any abnormal or emergency procedures that may help the situation. Next, we need to consider the terrain under us, and if there are mountains or ridges, turn so we descend parallel to them and not across. That way there is a chance of coming down in a valley and at least not banging head-on into the side of a hill. In about the same time frame as checking electronic terrain information, if we have a “nearest airport” selection we hit it! If we can make it, hopefully it has an instrument approach we can easily access. As mentioned before, we do need to be careful in just heading to the nearest airport, as this may take us back across the mountains instead of paralleling; it’s better to ding the airplane in a field than destroy it and us against a mountain. But again, we want to fly the airplane first, before fiddling with buttons or getting mesmerized with electronic displays. With the airplane under control and aimed for somewhere hopeful, let’s call ATC, declare an emergency, and if we don’t know, ask them about the nearest airport, if it has an instrument approach, and about the terrain as well. If we have electronic flight instruments with terrain display, and maybe synthetic or enhanced vision on the PFD, or even some personal smart devices, (if their use doesn’t cause too much fiddling versus flying), we’ll have fair idea where we are headed. No, it is not legal terrain-following data, but if we have no choice because of an engine failure, it’s a time for the better choice of uncertainty. If we are flying without technically advanced electronics with all the information talked about above, and have backed up our airway maps with sectionals, we’ll have an idea

where things are, possibly even an airport. If we’re on top of things, we’ll have a navigational aid or airport in mind that can help us out. On top of clouds, one often can see a wavelike pattern in the clouds below. If so, we descend in the low part, the trough of the wave, and we will possibly be over a valley. As the time nears when we’ll pop out of the clouds and face our quick landing, we slow down to a maneuverable, minimum airspeed, but not so slow as to stall until ready to touch. There are pretty good odds that we’ll see something before we hit, possibly having a chance to maneuver and pick a softer place. So our maneuvering speed should allow us to make some last-minute steeper turns without stalling. If we are going to stack an airplane, it’s best to do it under control. Full flaps and gear down. The gear will help the airplane to decelerate as it tears off, and the flaps, of course, will give the lowest speed. If we are wearing a shoulder harness and have maybe placed pillows in front of ourselves (if we can still see and fly) and our passengers, things may not turn out badly at all. The trick is to hit under control. It all sounds pretty desperate, but it isn’t quite that bad. We hope it never happens, and it probably never will. With all the above in mind, now we see the real potential of a ballistic parachute. Those who have developed and/or used them will know all the factors better than we do. However, it would seem whether to use it or not will take consideration of factors such as one’s experience and flying ability, versus what we know or don’t know about the weather, terrain, damage of our landing versus the parachutes’, parameters of the chute’s operation, and seemingly most important, the probability of all factors versus the well-being of those involved. In such an unavoidable situation with potential dire straits, the ballistic parachute seems a very appealing option.

All Is Normal and It’s Time to Get There Of course, en route flying is also handling navigation and ATC. It is also, during the not-so-busy cruise portion, a chance to plan the arrival, to get out the arrival airport area charts, study them for routes and holding points, and then program our electronic flight systems. It’s the time to study the instrument-approach procedure and firmly fix in our minds the key points of the approach, including the lowest altitude we’ll go to (minimums) and what the missed-approach procedure is, if we don’t get it.

19 Landing in Bad Weather As we approach the destination, weather takes on a more realistic feeling. Ceiling, visibility, wind, turbulence, and runway conditions become real, because we are about to cope with them. First we try to visualize the weather in relation to our descent. Is there ice or are there thunderstorms? If ice, as we’ve said, the job is to get well prepared (heat, props clean, etc.) and descend quickly to a landing before too much ice covers the airplane. With thunderstorms, we have to detour around them. Now let’s look back at the basic concept of approaches. There are basically two kinds. One is an approach providing both lateral and vertical guidance, with the most precise, called “precision approaches,” guiding an aircraft to the center of a specific runway. With these approaches, when we are on course and reach the minimum altitude, we either see the runway or not; consequently landing or making a missed approach. At current, most of these are flown off the ILS and GPS, with some larger aircraft using Inertial Guidance, augmented with GPS for higher accuracy. The other concept offers only lateral guidance towards either the airport or runway, depending on the design of the approach. They mostly function off VORs, Localizers, GPS and the few ADFs that are left, as well as Inertial Guidance. Without vertical guidance these approaches take us to a specific point at precise altitude, so we must see the runway and/or its environment, and from there we finagle an appropriate visual descent to landing. Because these approaches lack vertical guidance, they have higher minimums and are more demanding to fly. They are referred to as “non-precision approaches.” However, the name is kind of a misnomer, because all approaches offer some level of precise navigation. Most important to remember is that all of these approach types, whether precision or non-precision, should be flown with the same discipline and respect.

Flying the Approach We follow approach courses precisely, as prescribed on the approach plate, with absolutely no fudging. The altitudes on the approach plate are to be complied with accurately, which without vertical guidance means after we pass the approach’s final fix, we descend to the minimum altitudes, as referenced to distance along the course towards the runway. This is measured by either time or distance. Time is

more prevalent with approaches off VORs, Localizers and ADFs, although they can have distance reference as well. When using times for the approach, they must reflect our aircraft’s groundspeed . Using distance, instead of time, is much easier, and usually is the case with the rock-solid GPS approaches that are rapidly becoming the most popular; and being independent of ground-based electronics, provides ultimate utility for general aviation. There are three phases of an instrument approach: • The all-instrument part. • The transition period from instruments to visual. • The visual part. The instrument part is the easiest. This is a mechanical thing we learned when earning our instrument rating. But there are a few tricks and points worth talking over. First of all, it’s important to get the airplane settled down and ready for the approach. That means getting all the approach and landing checklist items out of the way well in advance. We shouldn’t be worrying about changing fuel tanks, throwing the flaps out, slowing the airplane down, and extending the landing gear, while trying to center the needles on any approach. That’s a frantic sentence and so is an instrument approach that we try to fly without planning ahead. We need to have everything set for landing before the approach is started.

The Instrument Part The following scenario is written as if we are hand-flying the approach, which we should be able to do easily and confidently just by using raw data indications. This is necessary, as mentioned earlier, even if we often use an autopilot for approaches, because if the autopilot fails at its job we need to take over immediately. If we are weak at hand-flying, it probably means we have a weak instrument scan, which makes it hard to follow the autopilot and consequently we’re unaware of what’s supposed to happen next. Then, if we have to suddenly take over and hand-fly, we’ll be way behind, which is a very bad predicament. If we are close to the ground, this rapidly becomes a very serious problem. The most important part is to keep on top of things at every moment. We are talking again of scanning and keeping headings where we want them, along with monitoring altitudes, descent rates, and airspeeds. Let’s remember the simple method of keeping a heading by watching our bank on the artificial horizon. If we never let a bank go unnoticed, we will not get far off the heading. Part of this is promptly changing the heading when it should be changed. In other words, if you think a heading change is needed, make it now! The idea is to keep a short rein on the entire process and never let the airplane get

far from the desired path. Scan often and act quickly but, of course, smoothly. Glideslope on an ILS, a GPS’s glidepath, or altitude change from approach without vertical guidance is mostly a matter of descent rate. A localizer needle is not flown; the directional gyro is flown to a heading, and we refer to the localizer needle, seeing if that heading keeps us on course. In descent, the vertical speed indicator, hopefully an instantaneous type, is the key. You set up a certain rate of descent and see how that keeps you on the glideslope. If we go below, the descent was too fast, and so we get back on the glide path and try a slower rate. We bracket the glideslope using the vertical speed instrument, just as we bracket the localizer with the directional gyro. So the two important instruments are the gyro and the vertical speed: one for course control and the other for descent. The artificial horizon, showing attitude in roll or pitch, is the instrument by which we make our heading or vertical speed change. If a bank occurs, the heading will change, and we stop it or bank to put our heading where we need it. If the horizon shows our nose down more than it has been, we bring the nose back where we want it; if we want to go down, we make a forward movement that shows on the pitch bar of the horizon. We should know about what pitch attitude and power setting it takes to come down a 3degree ILS, as well as what attitude and power settings are needed for different descent rates and airspeeds, should we need to fly a stepped-approach without vertical guidance. All this will vary depending on the wind. We refer to other instruments, too: airspeed to keep it within bounds and the altimeter to see how we are doing with our altitude. We often hear arguments concerning whether we control airspeed with the elevators and rate of climb with the throttles, or vice versa. Well, when tweaking the little corrections of an approach, it’s a silly argument, because what we’re managing is energy, and we do it the best way for the conditions we’re experiencing. If we’re below the glide path, our natural reaction is to pull back and get up to it. We zoom a little and get back, but if we’re quite low, and our zoom takes a long time, we will lose energy and slow down. Any experienced pilot knows this, and when pulling back automatically puts on some power. If it’s a little pull-up, and there is some extra speed, not much power is needed—maybe none. If the airplane is slow and quite low, a lot of power may be added right away, because pilot experience, subconscious, or whatever, tells the pilot that additional energy is required. Stopping to think which to do, add power or pull back, just isn’t the way to fly an airplane. It’s a smooth coordination of whatever it takes to get the job done under present conditions, and if a pilot doesn’t understand that, a lot of practice and learning is needed before trying to fly down an ILS, looking for the bottom of the clouds at 200 feet or less. To do it all, we scan and scan often. If we are flying a good old VOR or ADF approach, we’ll need to remember the course needle gets more and more sensitive as we are near the station. Many of these approaches cross the station, then continue on a course to the missed

approach point, and over the station the course needles briefly flail around in their sensitivity. As the airplane flies over the station, inexperienced pilots start making big turns and deviations, chasing the confused course needles, and the approach turns into a disaster. We don’t have to do this. Instead, as we approach the station, we should have things pretty well nailed down as to what the drift is and the required heading. After station passage, just apply that much drift to the next heading and cool it; wait a moment or two for things to settle down, and then resume tracking. When we go to the world of GPS, this issue goes away, and things become less mysterious. When we fly these approaches not having a glide path, we simply leave one altitude and go to another, with time or distance-derived fixes telling us when to do so. The approaches are usually designed so that there is rarely need to dive for it, but we should get on with the descent. The supposed smooth transition we make from starting and stopping the descent rate adds a little time and distance, so we don’t want to dawdle. The vertical speed indicator shows us how fast we’re descending and gives us a target. Obviously, we don’t want a descent rate so fast that it will make recovery at the desired altitude difficult; that’s dangerous. What our descent rate should be depends on a few easy problems of altitude to lose versus ground speed, giving a minimum rate of descent between the letdown fixes. This becomes our rate of descent. If it’s a minute between fixes, or from the final fix to our missed approach point, and we have 500 feet to lose, a 500-footper-minute rate of descent is the theoretical answer. But because we don’t really know our exact groundspeed—unless we have GPS—we should add a little. For that 500-foot-per-minute descent rate, we should probably use about 700 fpm, making sure we’ll get down in time. If we come up with one power-pitch setup giving us no more than 1,000 fpm, it will usually fit most approaches and keep things simpler. Our rate of descent during these approaches is also a guide for leveling off at the desired altitude. If the rate of descent is high, then we begin to level off farther above the altitude than we would with a low descent rate. We don’t want to go below our target altitude! Be positive when leveling off and don’t delay. Smoothly but concisely pull the nose up and get it done. A little practice in hitting altitudes from various descent rates will soon let us know what is needed. It’s good stuff to know before we start making approaches. The problem with stepped approaches, which we often call “dive-and-drive,” is they are not as safe as those with a glide path. If we plan to fly dive-and-drive approaches, we need to stay sharp and practice them. Fortunately, this is taking a marvelous change for the better, with GPS allowing glide paths to be created for so many approaches. Unless we are really sharp with stepped approaches, we probably should set higher personal minimums or stay away altogether. When we fly an ILS approach, the closer we get to the missed-approach point, the more sensitive it gets, even more so than for the VOR approach mentioned

earlier. Consequently, we want to get it tied down as far out as possible to reduce the need for excessive maneuvering closer in. An ILS approach is a little like a funnel. Well away from the runway, both the localizer and glideslope are wide, and as we get close in, they become narrower. This creates a tendency for us to be a little less precise near the outer marker, and then as we get in closer to the runway, if we don’t have our headings and sink rates organized, we begin chasing the localizer and glideslope indicators. The way to make a good approach is to get on course and stay there as soon as possible. A good portion of missed approaches don’t happen in the last part of the approach, although it looks that way; the miss probably started way back at the beginning of the approach, when the pilot didn’t get on track right away. The wind will change as we descend, and this will affect our drift and descent rate. We will have to change headings and descent rates to keep up with it, but the earlier we have these things under control, the easier it will be to pick up a change. And remember, the descent rate to stay on the glideslope is a clue to shear. One winter evening, an interesting event happened in Montreal. A cold front’s blast of chilly air and shifting wind lay between the airport and the beginning of our ILS approach. Checking weather just to the west showed northwest winds and snow. Their ATIS still was southwest and a little drizzle, but the report was nearly an hour old. Starting the approach to the southwest runway, it was smooth, light rain and the wind pretty much straight on our nose. Suspicious, we asked the tower for a weather update—gusty northwest wind with so-so visibility from snow. A few miles from minimums and just under 1,000 feet above the ground, it got pretty choppy, and the localizer needle quickly started to drive right. The weather update had our triggers cocked—quick 30-degree right turn, then immediately back left, settling on a good right crab. Kind of an airborne hula dance. It worked, and we broke out about 400 feet, snow blasting across the runway. That warm room at the Chateau Champlain hotel was very welcome. What we are trying to do all down the approach is to keep the changes as small as possible, but always within the limits of what’s comfortable between pilot and airplane. Close in, the ILS is narrow and the VOR station is small, so at those approaches’ ends, corrections need to be pretty small as well. It’s the time and place for maximum concentration.

Close in, Things Get Tight There’s a lot of pressure when we get in close on the approach; everything becomes tighter and tighter, and we must watch each instrument intensely, scanning the important ones frequently. This is the place where hands get sweaty. It’s the place, too, where the pilot has to be relaxed but alert. We must feel like a good athlete, intense in concentration but smooth in coordination and relaxed enough that we move freely. This comes by practicing, by getting the approach

under control early, and by talking oneself into the right mental attitude. When we get this ironed out, a good instrument approach is satisfying and frankly fun to fly.

Stick with It As we anticipate breaking out and seeing the ground, we should remember one of the most important parts of an instrument approach: stay with it! All approaches are not to the minimum altitude before seeing the ground, and actually most are not. The ground comes into view in various ways: through breaks in clouds, or a clean break out of cloud but into poor visibility, perhaps straight down in snow. We often see the ground before we have sufficient visibility to see the airport or runway. Seeing the ground—good old Mother Earth—whom we may not have seen for hours, doesn’t mean the approach is finished. It isn’t finished until we land and turn off the runway. Inexperienced pilots may attempt to continue the approach visually, thinking they know where they are, but with poor visibility and the field not yet in sight, things look different. Even an approach at an airport we know well will suddenly be as foreign as the moon when the visibility is only straight down. About then, the ground may disappear and that’s a profound shock! During ground contact navigation, the pilot probably has wandered from the approach course, but now, with visual references suddenly gone, there’s a wild attempt to get back on course, but it’s too late, and the approach is missed. When a pilot leaves the approach guidance and begins to navigate visually, the tendency is to begin a sneaky descent. It’s a natural reaction to get lower and have a better look, or it’s done because one isn’t scanning back to the instruments enough to check that altitude and airspeed are in safe territory. This pilot has entered a very dangerous domain! The altitudes for an instrument approach are set up to clear all obstructions along the approach path. It is best, by far, to follow these altitudes precisely and not be “suckered” into letting down below them because one can see the ground and gets the false impression that this makes everything okay. If there is enough ceiling, the approach altitude will put us in the best position to land. This descent to landing should be, if at all possible, about a three-degree glideslope, which is the same as an ILS. Visual glideslope reference is about the same. A fair wag for this is 300 feet per mile. If there isn’t enough ceiling and visibility, you shouldn’t be landing anyway. Why deviate from the procedure? There isn’t any good reason, so don’t. We cannot stress this enough. Whatever the approach, it is designed to lead us to the runway at the proper altitude, so why deviate from it? No, hang right with it until landing is assured. All this is especially important at night, even in fairly good visibility. The lack of a good solid reference can cause sensory illusions that will lead a pilot into the

ground when thinking all is well. A few lights or, in daytime, a dimly seen building or tree clump, combined with a wing being down and off-level nose position, can easily give the illusion that one is higher than appears. Lots of airplanes have piled up because of this. When the runway or approach zone slopes up, we think we’re higher than we really are. When runway lighting is set to an intensity lower than normal, we seem higher as well. Snow cover does the same thing, as do conditions of haze, smoke, and darkness; all of this makes us seem higher. These sorts of illusions have caused accidents. The answer is to trust instruments, not what we think we see. Stay with the instrument approach procedure until the runway is in view and it’s definite that we “have it made.” It is the dangerous place, when one casts aside instrument reference and uses only one’s eyes for guidance. Again, and again, we must not descend below the final altitude until the runway is well in view. What we can do is adjust our descent by reference to the runway, using our instruments to maintain proper attitudes and power settings for normal sink rates until we’re certain of our landing. Even at the point where we cross the runway’s end, we should be checking instruments—airspeed and especially altitude. With the runway in view, it is still possible to get too low, because our eyes play tricks; a look at the altimeter will sometimes be startling! But if one has taken frequent, quick looks at the altimeter during descent, even though “contact” with the ground, these surprises will not happen. During an ILS approach, keep in mind how much crab angle has been necessary to stay on course. Let’s say the ILS course is 50 degrees and it has taken about 60 degrees to stay on the localizer. This means that when we break out and see the runway, we’ll have a 10-degree crab angle. The runway will come into view favoring the left side of the windshield. The instinctive reaction is to kick out this crab and line up with the runway. We shouldn’t do this, because the airplane will then drift off the centerline, and it’s surprising how fast this happens. If the ceiling is low, we’ll probably not have time enough to maneuver around and get back on the runway before we reach it. Don’t attempt to get lined up with the runway once off to its side by any appreciable amount. It’s a case of, “You can’t get there from here.” The geometry and dynamics prohibit wild maneuvers that will get us back on the runway, unless we need only a small correction. It is time to swallow pride, pour on the coal, and do a missed approach. It’s a lot better than hooking a wing or engine pod or maybe crossing the runway to wind up in the boondocks. So on the ILS, note the drift and visualize where and at what angle the runway will come into view. Then, don’t be too quick to kick out the drift. See how you are doing first. You may have to hold it all the way to the ground.

When We See Again

Now we’ve made an approach with vertical guidance—ILS or otherwise—and have broken out of the clouds where we should. What happens? Unfortunately, and just like the approach without a glideslope, there’s a great tendency to push over and “go” for the runway. They call this the “duck under” maneuver. What it does is puts one too low, and it’s dangerous. There’s more than one way to duck under. So-called experts blame pilots for shoving it over to see the ground. Well, there are probably some cases of that nature, but I have more faith in pilots’ intelligence and will to live. Another reason for the duck under, as we’ve said, is flying contact and forgetting to scan the instruments frequently, because, basically, even though we see the ground, it is still IFR flying in low visibility. There is another reason for getting below the glideslope, and that’s shear. Normally, as we descend to land, the headwind becomes less during the descent. This causes airspeed loss and the aircraft’s nose therefore lowers, which, if we’re not right on top of it, will cause us to slide under the glideslope either on instruments or while trying to maintain visual contact. It’s one of the main reasons we’re startled to see an altitude loss when we look back at the altimeter. This isn’t dramatic shear, but simply a few knots of wind reduction during descent. It’s a subtle thing, but one to watch for. It emphasizes, again, the importance of scanning those instruments. To go back a bit, we were on instruments following the glideslope and had established an appropriate rate of descent. But the moment we look up and see the approach lights, we lose glideslope information. The approach lights let us see, but don’t do much for vertical guidance. The glideslope indication is inside on the instrument panel, not outside where we are looking. Unless there’s a Visual GlideSlope Indicator (VGSI ), we haven’t any glideslope reference. Looking back inside at the glideslope indicator doesn’t help, because the glideslope deteriorates as we get lower. ILS runways approved to CAT II and III have accurate glideslope indication almost to the ground, but others are not that precise. Their glideslope accuracy deteriorates as we approach the ground. How high this happens depends on various things, but terrain has a lot to do with it. Some glideslopes are good to 50 feet, but I’ve seen others that dip or become erratic as high as 150 feet. So at low altitudes, if the glideslope isn’t a CAT II or III runway, and the course bar suddenly makes a fast and pronounced excursion, don’t chase it. Simply hang on to the rate of descent that’s been taking you successfully down the glideslope; that’s your new one. This is a dangerous area. Enough airplanes have landed short under these conditions to prove the point. The airplane condition at that point aggravates the situation. It is going slowly. The pilot pushes over. The airplane goes through a shear zone. It sinks to a dangerous level before the pilot can catch the cue visually, if ever. That is why it would be nice to have those VGSIs on all instrument

runways, but such is not always the case. There are variations of VGSIs, and one should study and know them all. Equally important is to study the various lighting systems for approach, runway end, and runway lights before doing serious instrument flying and approaches. In relation to seeing in poor visibility, the availability of synthetic vision and enhanced vision is rapidly being added to electronic flight instrumentation. Synthetic vision creates an animated terrain image representative of where we are flying at any time. This terrain image is referenced from GPS position, and the wizardry that can relate actual terrain to a GPS position; then displays it as an animated image for our instrumentation. That image is usually presented on an aircraft’s primary flight display. Enhanced vision uses Infra-Red technology to see through night and cloud for an image of what’s out there. This is often displayed on aircraft MFD screens. Both give a good idea of what’s out the windshield, but for now, except for some military, government, and select civilian use, it’s reference-only for our personal aircraft. Again, we should not rely on it for an IFR approach, but it is a nice reference as we transition from electronic navigation to visual. Stay tuned; the future moves fast. Certain airline, military, and higher-end general aviation operations use headsup display, which offers images of basic aircraft parameters and attitude, as well as electronic guidance, on a see-through display in front of the pilot. It can allow lower minimums over comparable approaches without it, because of the ability to observe aircraft and navigation data while also allowing visual contact with where we are going. Years ago, the French airline Air Inter used it continuously and successfully with hand-flown, low-visibility landings. I (RNB) flew many approaches with it in Air Inter’s simulator, with some to zero-zero minimums, then making go-arounds; it is a beautiful, simple way to fly. Air Inter was a French airline with a marvelous weather record using the heads-up system. For now, however, we still have to deal with that transition zone between leaving electronics for visual guidance, unless we are making an automatic landing in a high-end operation. In summary, we first remember the rate of descent you have been carrying on the approach. On breaking out of the clouds, we take occasional quick looks at the instruments to see that we’re holding nearly the same rate. If we are, the descent path should be nearly correct, unless there is bad shear. An important point when flying an ILS is verifying that the altitude of our aircraft at the Final Approach Fix (FAF ) is the same as that published on the approach plate for the FAF. This confirms the correct altimeter setting. If it is off, we should verify the altimeter setting. If there are any uncertainties, we should discontinue the approach and get the altimetry organized before starting again. At minimums, there is not much room between us and the ground, so our altimeter has to be correct. What we’ve said in all this is not to trust our eyes for glideslope guidance

when visibility is low, especially at night. This applies to the VFR pilot under fairly good conditions, too. We’ve also said that an approach doesn’t end just because we can see the ground. And when we see the ground, we must kill the desire to push the nose down and duck under!

Autopilots Doing the Work As we have mentioned before, many aircraft have autopilots that make the approaches and do it magnificently. As also alluded to before, this doesn’t relieve the pilot from constantly monitoring how the autopilot is doing. It’s important to know the heading it’s flying, descent rate, and power in relation to what’s normal and what it is actually, whether our throttle is manual or automatic. Knowing all this will be very handy if the autopilot should suddenly disconnect or fail, and this does happen. And, of course, it’s a check that the autopilot is doing its thing properly. Careful observation of the approach has the pilot informed and ready to take over manually, for any reason, with minimum fuss.

Circling to Land Sometimes an approach is made but the wind is on a different runway, or the approach itself is designed to put us over the airport instead of lined up with the runway, and it is necessary to break off and maneuver, to an appropriate runway. This maneuver is referred to as “circling to land.” It is a dangerous procedure and requires higher minimums, generally 1,000 feet or more. In rain or snow, with poor visibility, perhaps at night, this is not easy. The tendency is to look out at the ground and runways, forgetting the instruments inside. It is very easy while doing this to have altitude slip away unnoticed and, with bank giving illusions, get far too low. How to do it? By instruments! Fly headings and maintain altitude with occasional looks outside to see how we’re doing until lined up on the heading of the desired runway and we can see it for landing. It is a watching-in and glancing-out procedure with constant reference to the necessary instruments. If at all possible, don’t do a circling approach under poor weather conditions, even though the minimums might allow us to do so. Also, if we have a choice between a circling approach and one straight in, take the latter.

To Touch the Ground So we’ve made a proper approach and now see the runway. What’s next? Actually, we continue with the descent and approach problem. We cannot get too low until the runway pavement is under us. While we want to get on the ground, we also don’t want to cut it so short, leaving the wheels on the last row of approach lights. It’s one of aviation’s many compromises in that you don’t want to land too long,

with the danger of going through the fence at the other end, and you don’t want to land too short, either. This brings up an important point about landing the airplane once the runway is securely under it. The point is to get it on the ground. This isn’t the time to float along with a little excess speed trying to gently slide the airplane on the ground and impress those riding along. Even if the landing is a little rough, get it on the ground where the wheels and brakes can begin to get it stopped. And in doing this, we want as much runway ahead as possible, in case we start aquaplaning on a water-covered surface or sliding on ice. So there’s a nice, delicate balance required in the approach. It starts with airspeed before the runway. We need enough to take care of gusts and shear, but not so much that we come screaming in over the runway, float halfway down it, and leave valuable runway behind, instead of using it to stop. These are the kinds of judgments pilots make alone and without help.

Low Visibility Now a few points about low visibility. It’s interesting to note the following table of the percent of missed approaches versus visibility, as taken from records at London airport for three years: Runway Visual Range (feet) 1,970-2,300 1,620-1,970 1,475 1,312

Missed approaches (%) 22.2% 30.6% 40.5% 45.5%

The above is older information, in an era when most landings were not automated. However, since most general aviation operations do not go below Category I minimums, this information still simply says that it is sometimes tough to make a successful landing when you cannot see. It says there isn’t any point being a hero, trying to get in under conditions that are just too tough. These low visibilities are generally there because of fog. During this condition, the visibility-measuring device may only see a portion of the runway area, although many runways at larger airports now have RVR measurement in two and possibly three or four areas along the runway, which give roll-out area visibility values. However, without RVR, one may roll out into a zero-zero fog patch. Very low visibilities are touchy and require objective analysis about whether or not it’s worth trying before doing so.

Ground Fog There’s another fog condition that deserves attention, and it doesn’t have to do with an instrument approach. We can fly in clear weather, day or night, and note that our destination reports zero-zero in ground fog. We get over the field and are surprised to see the runway and airport below us well in view. This is simply because we are looking down through a very shallow layer of fog, rather than through it horizontally. But if we say, “Heck, I can land in that,” and make an approach, we’ll get an awful shock as we descend and suddenly, about the time we start to flare the airplane for landing, go on solid instruments. What then? Pour on the coal and get out. If it’s too late for that, hold a steady descent rate and attitude until you touch. Then get stopped as fast as possible and hope you do before running out of runway.

On the Ground Okay, let’s clean up the last parts of our approach and landing. We’re on the ground and stopped; is the approach over? No. The next order of business is to quickly clear the runway. There’s an airplane a couple of miles out about to land, and the tower cannot clear it until we’re off the runway. So the obvious routine is land and clear the runway, as soon as possible. As mentioned in earlier chapter, if we are on an airport with high-speed turnoffs, sometimes they aren’t as high speed as they sound. If the runway and taxiway are wet and we start to turn off at fairly high speed, we can be shocked to find that the nose wheel may have turned toward the taxiway, but the airplane hasn’t. The nose wheel, without much weight and traction, is just skipping sideways, while the airplane is going somewhere between the runway and taxiway, which is in the boondocks! Find the speed at which our airplane can make that turn on a slick surface, and be there before trying to turn off. As to slippery, we chatted in the takeoff chapter about wet and dry snow and slipperiness and its effects on an aborted takeoff. On landing, we obviously have the biggest stopping concerns. With general aviation aircraft operating from smaller, and at times less fastidiously preened airports in adverse weather conditions, it’s worth considering some braking action criteria. The International Civil Aviation Organization (ICAO) has criteria for this: • Good braking = Dry snow < ¾ inch, water depth of ≤ ⅛ inch, and compacted snow with an outside air temperature (OAT) ≤−15 degrees C. (Good is the best braking criterion.) • Medium (fair) braking = Dry snow > ¾ inch and compacted snow> −15 degrees C. • Poor braking = Wet snow, slush, water > ⅛ inch and not melting ice. • Nil braking = Melting and/or wet ice. (This shuts down a commercial airport,

so one PIREP of nil braking can have interesting results.) • Unreliable braking =Wet snow, slush, standing water. (A potential legal quandary for the pilot in command, if they elect to land with this braking report.) As explained before, larger airports make braking-action tests, and report that versus just the coverage of water or frozen precipitation. However, if we’re at an airport that doesn’t make reports, this gives us a guide of what to expect and plan our operation accordingly. When you are operating on a hard-surface runway with a very thin coating of snow, at just freezing temperatures, it can be pretty much nil braking. Landing one night at Boston, with the temperature right at freezing −32 degrees F—and a very thin coat of snow, our brakes did little if anything. With anti-skid, one applies the brakes and holds them there, which that night resulted in nothing, except the “thump-thump-thump” of cycling anti-skid. Reversers were used gingerly, because aft engine jets tend to weathercock on slippery runways with any crosswind. We were light and landed accordingly, but used about twice the normal runway: at least 8,000 feet. As said in previous chapter, another thrill is weather cocking when barreling down the runway. The deal there is not to try and return to the runway centerline; instead, just realign with the runway direction. This prevents chasing the centerline, which risks starting an excursion all over again. By the way, frost and moisture on a grass runway is like greased lightning, with almost nil braking.

An Approach Briefing Before we go to work and fly one of these approaches, we should leave time to pull the whole arrival and approach into perspective. Just as we homogenize the takeoff with departure and takeoff briefing, we should have an approach briefing. Again lengthy at first, but when we do this as a habit, it becomes simpler and quicker. Below are some suggestions, open for individual preference: • Weather: Its affect on: • Descent and arrival • The approach (visibility, ceiling, winds, what we’ll see at minimums). • Airport/runway conditions. • NOTAMS: • Review them for airport and approach. • Standard Arrival Procedures: • Limitations and restrictions. • Terrain:

• Approaching the area and around the airport. • Approach Chart Review: • Approach used (type, limitations) • Chart date (currency but mostly comparison for two-pilot operation) • Navigation aid/system used (frequency/identification or programming verification) • Approach course (direction, any transition to it and altitude) • Final Approach Point/Fix (FAP/FAF) height • Minimums • Altimeter bugs/reminders • Missed approach point and procedure • Minimum sector altitude and navigational aid on which it is based • Highest obstacles within 50 miles • Small operational notes scattered around chart (radar required, descent limitations due to obstacles, etc.). • Figure any rates of descent and time of segment for non–glide path approaches. • Airport: • Runway, lightning, markings, length, surface, turnoffs, and so on. • Automation: • How we will fly the approach; automated or hand-flown? Lastly, if we are flying a technically advanced aircraft, we need to understand the system well, and make sure the approach is properly programmed. There are a couple of thoughts we feel worth mentioning. One is to carefully cross-check that we have programmed the proper approach; with so many different types, especially multiple choices to one runway, we can easily mess this up, especially if we are busy or sidetracked. Second, we need to have all the programming and related briefing done well before we are in the airport environment, preferably before the descent. If we have paper approach charts and other similar stuff, it’s a lot easier if they are held by a handy clip on the control wheel or instrument panel, so we can see them easily and without juggling them on our laps. There are nice ones in some airplanes, as well as ones we can buy. If we’re on the cheap, a good metal clip with a rubber band on each side hooked over the control wheel horns works well. With all this done, we are ready for descent and landing.

The Toughest Case Suppose the worst happened and for some difficult-to-explain reason one got caught with no alternates, no fuel, and a fog-covered, zero-zero airport as the only place to go. I (RNB) did this in Alaska on the Aleutian chain during World War II.

It wasn’t zero-zero, but it might as well have been. The ceiling was essentially zero, and the visibility was about 200 feet in snow and fog. Fortunately, I was over a good airport, Shemya, which had a long and wide runway. I came down the ILS (ILSs were new gadgets then) and carefully checked the descent rate needed to follow the glideslope. I flew the ILS as tight as possible. When we were under 200 feet and the glideslope started to wiggle and deteriorate, I just held the rate of descent until we touched. Then, control wheel forward (the B-17 is a tailwheel airplane), I slammed on the brakes and tried to stay on the localizer and get stopped before hitting something. We made it. Incidentally, I made a few practice approaches and go-arounds to get an idea of drift and descent rates before doing the one for keeps. What really impresses you is that with near zero visibility, you really don’t see! A few fuzzy lights aren’t enough for guidance, and you are helpless and feel helpless. This feeling can occur with visibilities up to 1,000 feet or so, depending on how fast you land. It’s an excellent lesson to make one realize that there are human limits, and we shouldn’t try to exceed them. Too many things happen too fast. In the airlines, we trained to 300-foot visibility in simulators, but in the real world rarely saw anything below 600 feet. It’s all done automatically, and your task is flying through it mentally, hand on wheel and throttles, waiting for something to go wrong; if rarely it ever does, but by nature of the business, we have to be prepared. The more interesting of automatic approaches were Cat II to 100 feet and 1,200-foot visibility, where you disconnected the autopilot and landed manually. That was the 727 world, which we mentioned earlier in the book, but at 100 feet and a third of a mile it was basically a trajectory to the runway, including superb in-runway lighting. Arguably a general aviation ILS to a 200-foot ceiling and 1,800-foot visibility, flying about 80 knots, is a more demanding task. That gives us around half a minute to the runway, which is plenty of time to break up a stabilized approach, if not disciplined with sink rate and drift correction. This returns to that concept of still referencing the attitude indicator, while also having visual contact with the runway environment. If we can fly the approach automatically, especially when the weather is at minimums, it is the best way to go. It allows us time to constantly check all phases of the approach, while computers and servos do the manual labor. However, when the approach is flown with the autopilot, by the time we reach minimums it is necessary to disconnect the autopilot, and immediately be capable of competent hand-flying. Without this capability of flying a coupled approach with the autopilot, a pilot flying very low approaches by hand, especially a single pilot, will be concentrating so hard on flying that there will be little if any time to check other important things. With the constant scanning of all parameters for the basic flying of the approach, it is hard to focus on peripheral aspects, such as looking for ground contact, airport environment indications, focusing on radio transmissions,

and transitioning to the ground contact scenario. It is hard to do, unless we are really current, on our game, and overall a very capable pilot. One reason really good pilots are quite capable is because they know when to admit something cannot be done to its best performance or safely, and accept limitations based upon this modest judgment. When we fly non-precision approaches, the world gets more difficult and inconsistent, because these approaches do not bring us as close to the runway, as does an approach with vertical guidance. There, we have to be even more disciplined. If, however, we take some lead from automatic approaches, where the autopilot takes the aircraft right down to landing, we find that accidents don’t seem to happen. This seems to prove the point that if folks stay with the approach right to the runway and overcome that desire to finish it by just eyeball, rather than staying with instrument reference, there will be a lot fewer accidents.

20 Teaching Yourself to Fly Weather With the idea that one crawls before walking, we can teach ourselves to fly weather. It’s a progressive, self-taught process that uses our own program and we set the challenges and pace. In the work of getting an instrument rating, we made practice IFR crosscountry flights, getting clearances, working the radios, managing navigation, gathering weather, and all the rest, even though we weren’t flying actual bad weather. Now it’s time to start our “home study” weather program. Each day, in our advancing times, the complexities of air traffic control, navigation, and communications grow, so that all the experience we can get in this area is important. If, on each flight, VFR or IFR, we are on a flight plan and doing all the work required, we will become facile with this part of the job and do it smoothly, almost automatically. Once this has become an easy task, we will have time to think about the weather.

Where’s the Emphasis? The balance in flying between ATC and its communications, versus the actual weather, has tipped toward ATC as a major challenge. Weather accidents can occur when pilots become so engrossed with an ATC altitude or route clearance that they get into trouble with ice or thunderstorms because their attention wasn’t on the weather as the primary problem. Pilots, especially new ones, tend to be more afraid of authority than of weather. This, of course, is illogical and perilous. If the route or altitude assigned doesn’t fit, it’s time to tell ATC that you want something different. If we are battling a difficult situation and ATC keeps pressing us with complex routings or unworkable requests, we should be prepared to tell them that we have urgent weather problems and need help, not hindrance. They will help if at all possible. All this comes more easily if we are prepared by being able to handle the ATC complexities, having a well-organized cockpit, knowing our aircraft and its systems, understanding the regulations, and having concise communications with headset and boom mic, not fiddling with a hand microphone. We need that hand for tuning and programming today’s avionics systems, with the other either flying or ready to, if we’re depending on autopilot. It is sometimes a challenge to find realistic weather when we’re either learning to fly or practicing, but ATC is always there as the real deal, not knowing whether we’re practicing or not. We

should practice as much as possible.

Learning the Weather Now let’s get on with learning to fly weather. The actual weather part we sneak up on by flying a little at first, more as we gain experience. Let’s take a look at a step-by-step method. These steps are flexible guides, and one’s own judgment will vary them as our ability grows along with our degree of comfort in the different stages of weather. The idea is to fly weather with safeguards that relate to our experience. After we feel comfortable flying weather conditions of the first step, we take on a little more in step two, and so on. The steps are: 1. 2. 3. 4. 5.

Fly good weather to good weather on top. Bad to good. Good to bad. Bad en route. Thunderstorms. Now, let’s talk about them.

Step One The first step, good to good , means we leave a point that has broken clouds or better and fly toward a point that has the same conditions and is forecast to remain that way or improve. The ceilings should be 2,000 feet or higher, the tops 7,000 feet or lower. No fronts should be moving toward the destination. Temperatures should be above freezing, and there should be no thunderstorms. This flight will mean climbing up through clouds for an on-top flight and descending through them at our destination. It will require watching weather to be certain things stay as we want them, and, of course, a flight plan and working the ATC system. This condition will generally be found in the stratocu cloud decks behind passage of a low pressure or front. It gives an opportunity to take on more or less weather, depending how close behind the low, or front, we take off. At first we might wait a day after the low passage for the stratocu deck to become thinner. Later, as we gain experience, we can take off closer and closer to the departing weather, until we are taking off with a ceiling that’s quite low, climbing to a top that’s quite high, or flying on instruments to a destination that’s overcast. Step Two This leads into step two, bad to good. It’s simply a continuation of the first step, but departing closer to the low and front until we are taking off just after its

passage. We should be careful not to take off before the front has passed or while it’s passing, because that can be a very demanding experience. The key thing in both these steps is that we are always flying toward good weather. We want to be certain it’s forecast to stay that way, too—no fronts moving in, as there might be if one took off from an airport that just had a warm front passage with weather improvement and then flew across the warm sector of the low to come upon a cold front. In this case, one should realize that out west somewhere there’s bound to be a cold front coming along that we don’t want to get involved with. When starting these first steps, it’s best to take off after a cold front has passed. Then there should not be any more fronts for quite a long distance. There are special situations, like the Los Angeles basin, that are excellent for bad-to-good flight experience. The frequent low stratus allow for an instrument departure and a climb to on top, where it’s CAVU, and then a flight to someplace in the desert, like Palmdale, where the weather is good. This generally can be done without running into the problem of fronts. We can back up and start these two steps over, but with some ice. The first sight of a smear of ice across the windshield is quite interesting if there’s a way out nearby. We can do this by climbing through a thin, below-freezing stratocu deck, 4,000 or 5,000 feet thick that has a good base, 2,000 feet or better, at both departure and destination. As we get more accustomed to ice, we can take this deck a little thicker and a little lower. (The airplane should be certificated for flight into known icing conditions, which admittedly is hard to find with most light general aviation aircraft.) Another good method of learning about ice is to fly in a stratocu deck that has ice, as well as in a freezing level at some safe altitude below, so one has the chance to descend below the clouds and melt any ice. This means the freezing level should be at least 2,000 feet or so above the highest terrain. This condition is often possible in the spring and fall. Step Three Step three is good to bad . This means to fly toward a destination that has weather approaching. The departure should have solidly good weather. Doing this, we can go to an area of low ceilings, shoot a low approach, and if there’s trouble, turn around and go back to where it’s good. We should plan, at first, on getting to the destination well ahead of any difficult weather, but be prepared for surprises. It may move faster than expected. This way, you’ll learn how foolish it is to fly to a destination that calls for deteriorating weather without having a safe place to run. As experience is gained in this step, one can fly to destinations with worse and worse weather. The key is to have that out—that safe place to run—which in this case is good weather behind us. This step should be tackled first without any

ice, and then we gradually work into ice as we’ve done in the previous steps. Step Four Step four is bad en route . This means we’ll take on a situation that has a good destination but something in between that is tougher than just a stratocu deck. It will be some kind of front. To start this, we should be without ice and thunderstorms, just as we begin each step. The destination should be forecast good and to stay that way or improve. Any front should be well past the destination before we take off. The takeoff point should be 1,000 feet or better and forecast to stay that way for at least two hours after takeoff. We progress in this step by taking off with the weather closer to our departure point. This requires thinking about a takeoff alternate—where to go if you must return and the takeoff airport has gone below limits. We develop this step until we are taking off with bad weather, flying through it en route, and landing at a point that has recently cleared. At this point, you have reached a pretty sophisticated level in weather piloting. But there still remain thunderstorms. Step Five To begin thunderstorms , we should fly with only air-mass types en route. They should be forecast as scattered, so we can wander around them and look them over from a safe vantage point. There shouldn’t be any fronts forecast within 500 miles of our route or destination. We should have lots of fuel. The destination may be covered by a heavy shower when we get there, and we want enough fuel to wait it out or go on to a thunderstorm-free destination. We want to arrive at the destination with lots of daylight remaining, three or four hours. Don’t go on instruments with thunderstorms in the vicinity. Don’t try to top them. Don’t cut too close between two of them. Don’t fly under the anvil overhang. The progression of learning weather around thunderstorms is difficult, because any thunderstorms beyond air-mass types will be frontal, and that may mean flying into instrument conditions while being unable to see any thunderstorms. Don’t do this without airborne radar and knowledge of how to use it. We could fly under high-level warm front thunderstorms as a progressive step, but this is flirting with heavy rain and low stratus clouds, which again means instrument flight. After air-mass thunderstorms, therefore, the next step is a big one, that of flying through fronts. As said before, even using radar and lightning detection equipment, it isn’t 100 percent guaranteed we’ll miss everything, so one may be forced to fly through a thunderstorm. Flying amongst thunderstorms in fronts and lows is the big time, and unfortunately has to be learned the same way we sometimes do in swimming, by diving in over our heads. A person should at least know how to fly turbulence

before dealing with fronts. Again, if in amongst thunderstorms, airborne radar, as always, is a must. And this, again, isn’t to help you fly through thunderstorms but is just an extension of your tools for keeping out of them. Lightning detection equipment and NEXRAD systems will be a big aid in avoiding thunderstorms in what we might call a “wide” sense. What we’re saying is don’t go into a heavy thunderstorm area, on instruments, counting on lightning detection and NEXRAD to help us weave through as we would with airborne radar. The learning steps outlined are not hard-and-fast rules. They are guides to start from and think about. But there are a few firm points that should be rules. 1. Always have an out. Fly toward good weather or from good weather that you can return to. 2. Take on ice only after other experience has been gained. 3. Don’t fool with thunderstorms for a long time. 4. Don’t get on instruments near thunderstorms without airborne radar or at least a preview with lightning detection and/or NEXRAD, so we can avoid the area. 5. Have lots of fuel. 6. Have lots of daylight remaining after the ETA. There are other rules, and they are in the book in many places, but if we summed up one weather rule it would always be: Have an out! And know the big picture! Looking back over these steps, we can see that weather flying experience isn’t gained quickly. We need several seasons, years, to see the things we should see, and experience the things we should experience. We must face the facts of weather flying. A total ability cannot be loaded into us as we would a computer or by reading a book, nor is it learned quickly. We must remain humble for a long time—for that matter all of our flying lives—and know when to quit or when not to go. An instrument rating is a beginning, not an endorsement that one can fly off into any kind of weather. During the learning of weather flying, we should be careful about reverting to VFR flying, instead of remaining IFR. If the weather remains bad, we are again back to flying down low and trying to weave in and out of mountains or even over flat terrain with minimum visibility, which is a sure way to trouble. Remember, VFR in marginal weather is the most dangerous way to fly!

21 Something on Judgment It is important to realize that in weather judgment, more determination is required to sit and wait than to fly. The press of wanting to get somewhere will overshadow the gumption it takes to drag the luggage back to town, miss a trip we really want to make, or delay getting home. Sadly, these reasons, and more like them, have caused many accidents. In judging weather before takeoff, then skillfully assessing and flying it once airborne, our attention and action should not be influenced by other factors, unless they become a part of the judgment, such as a mechanical problem that requires an immediate landing. As said before, it is not necessary to remain riveted to the idea that we must land at the airport of desired destination. There shouldn’t be a fixation on that. Weather changes and conditions may well make it prudent to go elsewhere, with personal and emotional influences not preventing us from tossing the desired destination aside in favor of a good, safe one.

Limitations The technical world of our day has put a lot of impressive equipment in airplanes to combat weather and make flying tempestuous stuff easier. We see the electronic flight instruments and autopilots that precisely fly programmed routes from nearly start to finish, at the same time offering warning and protection against pilots losing control of their aircraft. Electronic instruments that think for us, giving computerized cues for flying all phases of flight, including the toughest instrument approach. There are displays and warnings of obstacles in our flight path or being too low to the ground. We see artificially rendered terrain from accurate GPS location, thunderstorm information on the smallest electronic device, and airborne weather data that constantly updates. These systems offer greatly improved redundancy and reliability from the era of spinning gyros and mechanical interfaces. Approved deicing and anti-icing systems tempt us into the mysterious world of flying ice, then on landing, we have anti-skid brakes and reverse thrust on turbine aircraft. There are even a few aircraft offering ballistic parachutes that bring down a whole airplane. There is more coming, and with it a challenge toward defining what levels of basic ability and knowledge future pilots will need to be called qualified. But first, let us clearly and forcefully remember that all this equipment will

not fly all the weather. Mother Nature will periodically dish out weather that we simply cannot manage. We’ve gained much—the ability to land with little or no visibility if the airport and airplane are equipped. We can top much of the weather we once bounced in and worried about. There’s a long list, but no matter how superbly equipped an aircraft is, the inside of a thunderstorm is still harrowing, and severe shear on landing, instruments or no, can do the airplane in. Running low on fuel can menace flight. Landing in a hurricane can, too. Periodically, we are presented with weather of a most savage kind, and saying we’ve reached the age of “all-weather flying” is akin to the folks who said the Titanic was “unsinkable.” With our equipment has come the need for pilots to use it properly. We must program computers with the correct data. Keep close watch that all is working as desired and the aircraft is headed in the right direction, high enough to miss all terrain and avoid undesirable weather. This doesn’t come easily, because the sleekness of the airplane and its near perfection lull one into feeling that nothing can be wrong. Here’s where that overused but potent word, complacency, reaches its peak. The fact is that our modern aircraft demand more attention, not less, plus plenty of that old-time pilot’s belief that things can and will go wrong and you’d better have a skeptical eye roving the cockpit, and weather, on a regular basis. The equipment and smoothness of aircraft, the quiet shirtsleeve environment, and digital readouts flicking away easily give a false sense of security, which tends to overlook the basics. How very treacherous this false sense of security can be! This automation and potential false security makes it easy for pilots to either lose previously well-honed basic flying ability, and the thinking that goes with it, or, as new pilots, never be equipped with these basics in the first place, being taught to fly solely in conjunction with automated aircraft. As said before, there will be a day and time when we’ll have to fly and think with the raw basics, with no automation to help us. The reasons may be a blatantly obvious system failure, or even more insidious, a simple little issue that may lure us into staring at warnings or fiddling with buttons, ignoring basic flying indication and sense, while at the same time not realizing we’re headed for the ground. There is a chance it may also be dark, turbulent, of poor visibility but if we have learned the disciplines of knowing when to stop fiddling and successfully fly the aircraft, even from the raw basics, we can meet most tricks the new age throws at us. But without such skills, how treacherous this false sense of security can be! All this has sounded like talk of modern airline and corporate aircraft, leaving light aircraft out of the picture. With an up-to-date technically advanced general aviation aircraft, as far as instrumentation and “avigation” are concerned, the operation and discipline is little different than airline or corporate operations. However, there is still another false sense—that of what the airplane can do. It would be wise to remember that while well equipped, the airplane isn’t always of turboprop or jet performance. These turbine aircraft have real benefits, not the

least of which is zooming through ice and turbulence or other situations in a flash of high-performance ability—but again, as we well know, even they have their limits. Up until the recent past, the personal general aviation pilot had far less opportunity and mentorship to be as consistently well trained, current, and well equipped as professional flight crew members. Today we have more opportunity for this than ever before, which is a very good thing. We have also been affected by the complexity of the ATC system and the bureaucratic stifling of aviation that has required and produced training of a rote nature that misses out on judgment. We all wish there was a way to teach judgment, but it is difficult. Some people seem to have it naturally—horse sense —and a feeling for weather that intuitively tells them, “it just ain’t smart to go.” Others develop judgment by accumulating flying experience known as “fright time.” In flight, weather often takes a backseat to the system, the system being ATC, with the pressure of fast talk, keep ’em moving, land one right close after another, and don’t miss any instructions or make errors. With this comes the frustration of delays, holdings, long vectors, and reroutes. For the most part, this is not the fault of ATC controllers, but instead we are all stuck with the same challenges of the ATC system’s design and concept. Hopefully, the planned future improvements, designed to orchestrate through automation, will come forth and do their magic. In the area where most accidents occur, approach and landing, when operating at busier airports, there’s an element of being too engrossed in the fact that one airplane is landing right after another. We’re part of that and don’t want to interrupt it, so we continue our approach, sort of mesmerized by the idea of landing, without really thinking about weather. The pilot ahead landed or departed, why shouldn’t I? It’s a form of competition, too. We may not be willing to be the oddball, the one who couldn’t make it and had to pull out, disrupting everything. Unfortunately, it takes courage to break out of the “norm,” to say there’s a thunderstorm too close and I’m going elsewhere, or the crosswinds are too strong and I want a different runway. But we must remember that weather is the first priority—not ATC, not the airplane ahead or the airplane behind, or the fact that ATC may send us off to Lord knows where if we want to stray from the routine f low. But the law of preservation and the rule of safety first must be the way. Despite all our modern equipment, weather will, from time to time, humble the structure of aviation. The pilot’s task is to be aware of these times, be responsive to them and have enough grit to take action. This applies whether the pilot has 30,000 hours or 10. We have all heard the talk of our world’s weather becoming worse. Some ask how that will affect aviation. One indication is that we are seeing stronger storms, both as low pressures and thunderstorms. With this, there have been indications of larger water droplets, which will affect both rain and icing conditions. Maybe more changes are out there. However, it would seem still knowing the tried and

true theories of weather, and how it tells us its story, will still allow us to apply it to our flying, with the same prudent decisions that have worked since flying began. I (RNB) was fortunate to fly with pilots who showed me what command meant. We were flying DC-2s and DC-3s then. On one of my first copilot flights, the captain was Jim Eischeid, a veteran with a special reputation for being an excellent weather pilot. We were going to fly Flight 7 from Newark to Chicago. It was a rotten night, with Chicago forecast low, ice en route. I stood next to Jim in the dispatch office, discussing the weather with the meteorologist, somewhat in awe, anxiously awaiting the flight to see how this man, whom no weather could stop, would handle it. Imagine my surprise when he turned to the dispatcher and said, “It’s no good. I cancel!” He knew when not to fly. Jim retired after a long career that went from open-cockpit mail planes to Connies 1 , and he never scratched one of them. Now we fly in an era that comes closer to all-weather flying. We can fly more weather far safer than we did back then and, after all, we want the airplane to work and deliver people and goods reliably, but we have not truly reached the stage of total all-weather flight, from general aviation to airline, and we probably never will. In revising this book into the 5th edition, now 2013, it’s been about 75 years since Jim Eischeid cancelled that flight. Thousands more flights have been cancelled since then, and despite different combinations of pilots, equipment, and conditions, the ultimate concept of looking it all over and making that decision has been the same. There will always be some time when it will be wise for a pilot to say, “I cancel” or “I’m diverting!” The thing is to know when it’s that time for each of us, and then have the guts to do it.

1 . Connie is a nickname for the elegant, four engine, Lockheed Constellation, which represented the peak and end of the piston-engine airline era. The next step was the jet age, but Jim Eischeid, and many of his mailpilot-era pioneering compatriots, reached retirement age before the jets came into service.

Suggested Reading and Websites Books about Weather Anderson, Bette Roda. 1975. Weather in the West . Palo Alto, Calif.: American West Publishing. Bradbury, Tom. 2004. Meteorology and Flight , 3rd ed. London: A & C Black. Byers, Horace Robert. 1937. Synoptic and Aeronautical Meteorology. New York: McGraw-Hill. Dunlop, Storm, and Francis Wilson. 1987. Weather and Forecasting . New York: Collier/Macmillan. Edinger, James G. 1967. Watching for the Wind . New York: Doubleday. Federal Aviation Administration (FAA) and National Oceanic and Atmospheric Administration (NOAA). 1975. Aviation Weather, AC 00-6A , rev. ed. Washington, D.C.: United States Government Printing Office. Lester, Peter F. 1994. Turbulence: A New Perspective for Pilots. Englewood, Colo.: Jeppesen. Lester, Peter F. 2007. Aviation Weather , 3rd ed. Englewood, Colo.: Jeppesen. Pagen, Dennis. 1992. Understanding the Sky: A Sport Pilot’s Guide to Flying Conditions. Spring Mills, Penn.: Sport Aviation Publications. Petterssen, Severre. 1968. Introduction to Meteorology, 3rd ed. New York: McGraw-Hill. Wallington, C. E. 1977. Meteorology for Glider Pilots . London: John Murray. Whelan, Robert F. 2000. Exploring the Monster: Mountain Waves, the Aerial Elevator. Niceville, Fla.: Wind Canyon Books. Williams, Jack. 1997. The Weather Book , 2nd ed. New York: Vintage Books.

Books on Weather Information Chaston, Peter R. 2002. Weather Maps: How to Read and Interpret All the Basic Weather Charts , 3rd ed. Kearney, Mo.: Chaston Scientific. Federal Aviation Administration (FAA) and National Weather Service (NWS). 2010. Aviation Weather Services, AC 00-45G. Washington, D.C.: United States Government Printing Office.

Books on Flying the Weather Collins, Richard L. 1999. Flying the Weather Map , 2nd ed. Newcastle, Wash.: Aviation Supplies and Academics. Collins, Richard L. 2002. Thunderstorms and Airplanes . Newcastle, Wash.: Aviation Supplies and Academics. Federal Aviation Administration (FAA). 2009. Advanced Avionics Handbook,

FAAH-8083-6 . Washington, D.C.: United States Government Printing Office. Horne, Thomas A. 1999. Flying America’s Weather: A Pilot’s Tour of Our Nation’s Weather Regions. Newcastle, Wash.: Aviation Supplies and Academics. Newton, Dennis W. 2002. Severe Weather Flying , 3rd ed. Newcastle, Wash.: Aviation Supplies and Academics.

Digital Media Collins, Richard L. 2002. Advanced Weather Flying. Batavia, Ohio: Sporty’s Academy. Collins, Richard L. 2008. Flying Weather . Batavia, Ohio: Sporty’s Academy. Dennstaedt, Scott C. 2012. Best of AvWxWorkshops.com. Chesapeake, Va.: Chesapeake Aviation Training. Fovell, Robert G. 2010. Meteorology: An Introduction to the Wonders of the Weather. Chantilly, Va.: The Teaching Company. National Aeronautics and Space Administration (NASA)/John H. Glenn Research Center at Lewis Field. 2005. NASA In-Flight Icing Training for Pilots. Cleveland, Ohio: NASA. National Aeronautics and Space Administration (NASA)/John H. Glenn Research Center at Lewis Field. 2004. Supercooled Large Droplet Icing. Cleveland, Ohio: NASA.

Web Access National Weather Service (NWS) Sites http://www.weather.gov —NWS main website http://w1.weather.gov/glossary —NWS Glossary http://www.aviationweather.gov —NWS Aviation Weather Center http://www.aviationweather.gov/stdbrief —NWS Aviation Weather Center Standard Briefing Guide and related weather information access. http://www.aviationweather.gov/adds —NWS Aviation Digital Data Service (ADDS) http://www.crh.noaa.gov/dtx/afdterms.php —Terms of the NWS Area Forecast Discussion http://www.srh.noaa.gov —NWS Southern Region Headquarters site. Userfriendly map of the United States from which one can access each NWS office’s dedicated website. Also a source through which to link into the Area Forecast Discussion (AFD)/Forecast Discussion. http://www.nws.noaa.gov/view/states.php —NWS source to access weather data that is state-specific. http://www.wpc.ncep.noaa.gov —NWS Weather Prediction Center. Part of the National Centers for Environmental Prediction (NCEP), a primary center for NWS weather processing. Excellent source of detailed weather maps and data.

http://www.aviationweather.gov/general/pubs/front —NWS AWC publication The Front . Articles that inform of NWS products, including their operational use to aviation. http://www.srh.weather.gov/jetstream/index.htm —NWS AWC Jetstream online school for weather. Numerous and excellent tutorials covering weather phenomenon. National Oceanic and Atmospheric Administration (NOAA) Sites http://weather.aero —National Center for Atmospheric Research–specific web-site for ADDS experimental data. http://www.wrh.noaa.gov/zoa/mwmap3.php?map=usa —Central Weather Service Unit (CWSU) National Map for Air Traffic Control that allows access to nationwide METAR, TAF, and further detailed information. http://www.spc.noaa.gov —Website for the Storm Prediction Center (SPC). Model Analysis—Including Model Output Statistics (MOS) and Skew-T Data http://rucsoundings.noaa.gov —Website to access atmospheric soundings/ SkewT data. http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller —National Center for Environmental Prediction. Weather model analyses and guidance. www.nws.noaa.gov/mdl/synop/products.php —Current Model Output Statistics (MOS) Forecast Products (all MOS products—long range, short range and graphical), as well as descriptions to read the data. Federal Aviation Administration (FAA) Sites http://www.duats.com —FAA-approved weather and flight-planning source. https://www.duat.com —FAA-approved weather and flight-planning source. http://www.faa.gov/pilots/safety/media/ga_weather_decision_making.pdf General Aviation Guide to Weather Decision Making.

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Other Weather Sources http://www.radar4pilots.com —Archie Trammell’s airborne weather radar school and related newsletter. http://www.rtiradar.com —Radar Training International, which offers customized airborne weather radar training seminars. http://weather.unisys.com —Unisys weather service, which offers a plethora of weather data, including atmospheric modeling forecasts. http://www.flightplanning.navcanada.ca —Excellent weather data for Canada and nearby portions of the United States. http://airfactsjournal.com —An online journal that emulates the unique offerings of the original Air Facts magazine. The writings provide diverse information, education, and enjoyment. Through the journal’s philosophy and encouragement, a great deal of the material is written by the readers, making

Air Facts a journalistic home for the general aviation pilot and participant.

Acronyms and Contractions A/FD ACARS ADAHRS ADC ADDS ADF ADI ADS-B AFD AFSS AHRS AIM AIRMET Altocu AOPA ARTCC ASI ASOS ATC ATC ATIS AWC AWOS C CAT CAT I CAT II CAT III CAVU Cb CG Cu CuNim CVG CWSU

Airport/Facility Directory Aircraft Communication Addressing and Reporting System Air Data, Attitude and Heading Reference System Air Data Computer Aviation Digital Data Service (website for NWS/AWC weather data) Automatic Direction Finder Attitude Direction Indicator (Artificial Horizon or Horizon) Automatic Dependent Surveillance–Broadcast Area Forecast Discussion (Forecast Discussion) Automated Flight Service Station (same as modern FSS) Attitude and Heading Reference System Aeronautical Information Manual Airmen’s Meteorological Information Altocumulus cloud Aircraft Owners and Pilots Association Air Route Traffic Control Center Airspeed Indicator Automated Surface Observation System Air Traffic Control Air Transport Command (World War II military air transportation organization) Automatic Terminal Information Service Aeronautical Weather Center (aviation division/website for NWS) Automated Weather Observation System Degrees Celsius Clear Air Turbulence Category I approach minimums Category II approach minimums Category III approach minimums Ceiling and visibility unlimited Cumulonimbus cloud Cloud-to-ground lightning Cumulus cloud (CU or cu also used) Cumulonimbus cloud Cincinnati/Northern Kentucky International Airport Center Weather Service Unit

DG DME DP DUAT DUATS EADI EFAS EFD EFIS EHSI ESRL F FA FAA FAF FAP FAR FBO FD FIKI FMS FSS G GPS GS GSD HF HIWAS hPa HPC HSI HUD HVFR IAS IC ICAO IFR in Hg INS

Directional Gyro Distance Measuring Equipment Departure Procedure Direct User Access Terminal Direct User Access Terminal Service Electronic Attitude Direction Indicator En Route Flight Advisory Service (also known as Flight Watch) Electronic Flight Display Electronic Flight Information System Electronic Horizontal Situation Indicator Earth System Research Laboratory Degrees Fahrenheit Area Forecast Federal Aviation Administration Final Approach Fix Final Approach Point Federal Aviation Regulation Fixed-base operator Flight Director Flight Into Known Icing Conditions Flight Management System Flight Service Station “g-force” Global Positioning System Glideslope Gridpoint Statistical Interpolation High frequency Hazardous In-Flight Weather Advisory Service Hectopascals Hydrometeorological Prediction Center Horizontal Situation Indicator Heads-up display Hazardous Visual Flight Rules (nonofficial term to emphasize risky state of MVFR) Indicated airspeed Intracloud lightning International Civil Aviation Organization Instrument Flight Rules (criteria between 1,000 feet ceiling/3 statute miles visibility to LIFR) Inches of mercury Inertial Navigation System

IRS IRU

Inertial Reference System Inertial Reference Unit

ITCZ IVSI JFK LAMP LF LIFR

Intertropical Convergence Zone Instantaneous Vertical Speed Indicator John F. Kennedy International Airport Localized Aviation Model Output Statistics Program Low frequency Low Instrument Flight Rules (ceiling less than 500 feet/visibility less than 1 statute mile) Low-Level Wind Shear Alert System Lateral Navigation Line-Orientated Flight Training Light Sport Aircraft Millibar (in relation to altimeter settings, same as hectopascals) Aviation Routine Weather Report Multifunction display Model Output Statistics Marginal Visual Flight Rules (criteria between ceiling of 1,000 feet and 3 statute miles visibility to VFR minimums) National Aeronautics and Space Administration National Center for Environmental Prediction Nondirectional beacon Next Generation Air Traffic System Next Generation Radar (ground-based Doppler radar) National Oceanic and Atmospheric Administration Notice to Airmen National Weather Service Outside air temperature VOR (an old term) A 180° turn International Scientific and Technical Organization of Soaring Precision Approach Path Indicator (type of VGSI) Planetary Boundary Layer Primary Flight Display Pilot Weather Report Probability (as referenced in written aviation weather information) Rawinsonde observation (tracking of radiosonde equipment on a weather balloon) Ram Air Temperature

LLWAS LNAV LOFT LSA Mb METAR MFD MOS MVFR NASA NCEP NDB NexGen NEXRAD NOAA NOTAM NWS OAT Omni 180 OSTIV PAPI PBL PFD PIREP PROB RAOB RAT

RAT RNAV RNB ROB RPM RVR SID SIGMET Skew-T log-P SLD SPC SPECI STAR Stratocu T T&B TAA TAF TAF-TDA TAS TCAS TDWR TDZL TEMPO TKS TRACON Trop TRW TV TWA USAAF USWB UTC VASI VFR

Ram Turbine Area Air Navigation Robert N. Buck (Weather Flying’s first author, editions one to four) Robert O. Buck (Weather Flying’s second author, fifth edition) Revolutions per minute Runway Visibility Range Standard Instrument Departure Significant Meteorological Information Thermodynamic diagram for weather (atmospheric) analysis Supercooled Large Droplets Storm Prediction Center Aviation Selected Special Weather Report Standard Terminal Arrival Route Stratocumulus cloud Thunderstorm Turn and Bank Indicator (Turn and Slip) Technically advanced aircraft Terminal Aerodrome Forecast TAF Tactical Decision Aid True airspeed Traffic Alert and Collision Avoidance System Terminal Doppler Weather Radar Touchdown Zone Lights Temporary (as referenced in written aviation weather information) Tecalemit/Kilfrost/Sheepridge Stokes (last names of developers for TKS anti-/deicing system) Terminal Radar Approach Control Tropopause Thunderstorm Television Trans World Airlines (pre-1946, Transcontinental and Western Air) United States Army Air Forces (World War II name, before it was named U.S. Air Force) United States Weather Bureau (now known as the National Weather Service) Coordinated Universal Time (also known as Z-Time or “Zulu”) Visual Approach Slope Indicator (type of VGSI) Visual Flight Rules

VGSI VHF

Visual Glideslope Indicators Very high frequency

VNAV VOR VSI WAAS WPC

Vertical Navigation VHF Omni-Directional Radio Range Vertical Speed Indicator Wide Area Augmentation System Weather Prediction Center

Index A/FD. See Airport/Facility Directory Abbreviated Briefing ACARS. See Aircraft Communications Addressing and Reporting System ADAHRS. See Air Data, Attitude, and Heading Reference System ADC. See Air Data Computer ADDS. See Aviation Digital Data Service ADI. See Artificial Horizon, or Attitude Deviation Indicator Adiabatic cooling process Advanced Avionics Handbook (FAA-H-8083–6 ) Advective cooling process Adverse conditions Advisory Plotting Chart Aerodynamic braking, ice and Aeronautical Information Manual (AIM) Aeronautical Weather Center (AWC) AFD. See Area Forecast Discussion AFSS. See Automated Flight Service Station AHRS. See Attitude and Heading Reference System AIM. See Aeronautical Information Manual Air: cooling of moisture in mountain wave and movement visualization sinking temperature influencing molecules of unstable mass of Air Data, Attitude, and Heading Reference System (ADAHRS) Air Data Computer (ADC) Air-mass thunderstorm cloud base hint for flying under occurrence of Air Route Traffic Control Center (ARTCC) Air Traffic Control (ATC) clearance given by controller’s job at

flight plan deviation and frequency switch and help from ice accumulation advised of in-house meteorologists at learning to fly weather and NEXRAD used by precipitation levels of rushed takeoff and system design of thunderstorms and Air Traffic Control-cleared route, distance and Airborne data link weather Airborne radar frozen precipitation and ground clutter with limitations of maintenance of rain detection and signal of on standby thunderstorm avoidance and Aircraft Communications Addressing and Reporting System (ACARS) Airmen’s Meteorological Information (AIRMET) Airplane: boots bonded to cockpit preparation and deicing of FIKI certification of high-altitude turbulence stalling in lightning strike on protection of retrimming of self-righting tendency of wind shear and yaw and banking of Airplane performance: at density altitude ice influencing range and in tropopause vortex influencing

wind influencing Airport alternate choice for identifiers landing place other than late weather at location of takeoff rushed by weather at Airport/Facility Directory (A/FD) Airspeed drop in for forced landing thunderstorms and Airway clearance, calling for Alternate airport Altimeter accuracy of setting of Altitude: adjustment of clearance density mountains and temperature and turbulence and world soaring record of Alto clouds Antistatic hardware Approach, missed in thunderstorms Approach and landing: altimeter and airspeed for autopilot and in bad weather braking action reports and briefing for circling clearing runway lining up for descent rate and glide path

glideslope GPS ground fog and groundspeed and guidance for gyro heads-up display for headwind and ICAO criteria for ice and ILS instrument lights for low visibility and minimums and at night non-precision runway minimum practices and sticking with it during thunderstorm touch down vertical guidance for vertical speed and visual approach wind shear and winds and Area Forecast (FA) Area Forecast Discussion (AFD) ARTCC. See Air Route Traffic Control Center Artificial Horizon, or Attitude Deviation Indicator (ADI) ASOS. See Automated Surface Observation System ATC. See Air Traffic Control ATIS. See Automatic Terminal Information Service Attitude and Heading Reference System (AHRS) Attitude flying example of instruments for Augmented indications, dependence on Automated Flight Service Station (AFSS) Automated Surface Observation System (ASOS) Automated Weather Observing System (AWOS) Automatic Terminal Information Service (ATIS)

Autopilots: approaches and landing checks against as crutch departures and double checking of dual-axis failure of managing of high-altitude turbulence and instruments and overreliance on programming of reliance on requirement of single-axis smart sophistication of three-axis thunderstorms and turbulence and during VFR Aviation Digital Data Service (ADDS) Aviation Routine Weather Report (METAR) Aviation Safety Briefing (FAA) Aviation Weather Center (AWC) Aviation Weather Services AC 00–45G (FAA) AWC. See Aeronautical Weather Center; Aviation Weather Center AWOS. See Automated Weather Observing System Ballistic parachute Barometric pressure, isobars connecting Base reflectivity Basic-T Instrument Display Bent-back occlusion Big weather picture computerized weather and en route weather and meteorologist and from satellite and NEXRAD Black-bag flight kits Blind-flying

“Blind or Instrument Flying? ” (Stark) Blow-off clouds Bluetooth-transmitted flight planning Boeing 777 simulator Boots, pulsating Bracketing Braking action reports Briefing. for approach and landing Byer, Horace R. Canned routes Carburetor icing CAT. See Clear Air Turbulence Category I minimums Category II minimums Category III minimums CAVU. See Ceiling and visibility unlimited Cb. See Cumulonimbus Ceiling and visibility unlimited (CAVU) Ceilings Cell generation, in thunderstorm Center Weather Service Unit (CWSU) Charts and maps electronic compared to paper felt marking pens for paper presentation of pressure-level sectional special language for studying of surface Checking weather: before, during, and after flight self-briefing and Circling approach Cirrus clouds Cities: terrain influenced by VFR near Clear Air Turbulence (CAT)

flying through forecasting of isobars and jet stream and tropopause and Clearance. See also Air Traffic Control altitude studying of Cleared for takeoff Closed zipper Cloud streets Clouds. See also Thunderstorms blow-off creation of en route front characteristics and lentricular snow from stacking of story told by tops types of weather influenced by Cockpit: formulas stored in glass good housekeeping of preparation of Code language rough mental picture created by weather briefing and Coffin corner Cold front flying through ice and rules for thunderstorms along weather characteristics of Command bars Composite reflectivity Computerized weather big picture and

from television websites for Convective-layer turbulence Convective SIGMET Convective weather detection Convergence, area of Cooling by radiation Copilot, necessity of Coupled-approach Cowel heat Cumulonimbus (Cb) Cumulus clouds building of as thunderstorm predictor turbulence and Current conditions CWSU. See Center Weather Service Unit Data, raw Data-linked lightning mapping information Deck, ice Density, temperature and Density altitude Departure and takeoff: bashfulness and briefings for concentration and equipment and functional layers of ice and instrument flying and last minute checklist for minimums and programming for radio and runway surface and in snow taxi time during thunderstorms turbulence during visibility and wind and

Departure Procedures (DP) Departure to destination, range needed for Descent: ground speed and ice and turbulence during Descent rate, for approaching landing Destination forecast Dewpoint DG. See Directional Gyro Direct User Access Terminal (DUAT) Direct User Access Terminal Systems (DUATS) Directional Gyro (DG) Distance: ATC-cleared route and range and between two points Divergence Downdraft DP. See Departure Procedures Drift Dry climate: precipitation inconsistency and thunderstorms and Dry microburst Dual-axis autopilot DUAT. See Direct User Access Terminal DUATS. See Direct User Access Terminal Systems Duct design Dust devil Dutch roll EADI. See Electronic Attitude Director Indicator EFAS. See En Route Flight Advisory Service EFIS. See Electronic Flight Information System EHSI. See Electronic Horizontal Situation Indicator Eischeid, Jim Electrical discharge on airplane chances of emotion and protective materials against

types of Electronic Attitude Director Indicator (EADI) Electronic charts, paper charts compared to Electronic flight displays, failure of Electronic Flight Information System (EFIS) Electronic Horizontal Situation Indicator (EHSI) Emotions: control of electrical discharge and en route weather and fright as irrational optimism and requesting help and self-discipline and during thunderstorms during VFR En route: clouds and duties during EFIS systems and flight log and forecast fuel consumption relaxation in thinking ahead during what it is like En Route Flight Advisory Service (EFAS) En route weather: aloft winds and asking why and if questions for big picture weather and clear, good weather and detour for deviation of emotions and experience and forecasts and fronts and hourly report and IFR and meteorologist consulted during occlusions and zippers and

pilot’s view of VFR and weather reports for Engine failure: fuel and ice and Engine vapor lock Engines: backfiring of temperature and Enhanced vision Equipment and instrumentation approach plates autopilots and Basic-T Instrument Display comparative checks against complexity of condition and type of constantly scanning of for departure and takeoff departure procedure for electronic seduction and emergency lighted standby failure of hazards increased from housekeeping needed for layout of lighting for limitations of in location with pilot minimum needed of modern technology influencing for navigation paper and clipboard needed as paperwork and gadgets as pen/pencil holder as periodic checks for power for preparation of proficiency of development of radar and lightning detection systems

reliability of scanning of simplicity of six-pack round dial Basic-T location of turn and bank upgrade of for wind shear wires and plug-in attachments for FA. See Area Forecast FAA. See Federal Aviation Administration FAF. See Final Approach Fix FARs. See Federal Aviation Regulations FBOs. See Fixed-base operators Federal Aviation Administration (FAA) Federal Aviation Regulations (FARs) Field, as landing place FIKI. See “Flight Into Known Icing Conditions” Final Approach Fix (FAF) Fixed-base operators (FBOs) Flight Director checks against flying through raw data not matching with “Flight Into Known Icing Conditions” (FIKI) Flight log Flight Management Systems (FMS) Flight planning: ATC deviation Bluetooth-transmitted self-briefings and sources of for VFR Flight Service Station (FSS) briefings from consolidation and centralization of human communication from opening remarks to pilot briefings by on VFR Flight Watch (EFAS)

Fluid anti-icing formula for precipitation and success of types of FMS. See Flight Management Systems Fog ground turbulence and of windshield Forced landing Forecast accuracy of destination en route weather and future during holding for ice inaccuracy of prediction of testing of time limits of of wind shear The Front Frankenfield, Jim Fronts: cloud characteristics close to en route weather and ice and in Northeast Corner stalled surface wind and thunderstorms and toughness of types of weather along on weather map winds and FSS. See Flight Service Station Fuel: airplane capacity and engine failure and

Fuel consumption: during climb en route headwinds and tailwinds influencing during holding planning for by weather Fuel reserve Glass cockpit Glide path Glider pilot Glideslope Global Positioning System (GPS) navigation sectional chart compared to VFR and Government regulations, on fuel reserve GPS. See Global Positioning System Gradient wind, surface wind and Gress, Charlie Ground clutter Ground fog Groundspeed Gusty winds Gyro. See also Directional Gyro approach and slaved Hail damage from location criteria on Hand-flying: ice and by pilots skills for in turbulence Hazardous In-Flight Weather Advisory Service (HIWAS) Hazardous Visual Flight Rules (HVFR) Haze. See also Pollution Heads-up display, for approach and landing Headwinds: approach and

fuel usage influenced by hazards of ridges and Heavy rain HF. See High frequency High-altitude turbulence airplane stalling in autopilots and High frequency (HF) High pressure areas. See Ridges Highs HIWAS. See Hazardous In-Flight Weather Advisory Service Holding: range during unpredictability of weather forecast and Horizontal Situation Indicator (HSI) Hot wings Hourly reports HPC. See Hydrometerological Prediction Center HSI. See Horizontal Situation Indicator HVFR. See Hazardous Visual Flight Rules Hydrometerological Prediction Center (HPC) IAS. See Indicated airspeed ICAO. See International Civil Aviation Organization Ice accidents from aerodynamic braking and airplane performance influenced by airspeed drop from approach and landing and avoidance of cloud tops cold front and cloud deck departure and takeoff and descent and drag created from engine failure and fluid anti-icing and flying away from

forecast advances for formation of fronts and hand-flying and heat for kinds and classes of mountains and 180 degree turn away from orographic effect and propellers covered in pulsating boots breaking up radio mast covered in snow haze and taxiing and ATC advised of temperature and vibrations from warm front and windshield and IFR. See Instrument Flight Rules ILS. See Instrument landing systems Indicated airspeed (IAS) Inertial Guidance Inertial Reference Systems (IRS) Inertial Reference Units (IRU) Instantaneous Vertical Speed Indicator (IVSI) Instrument. See Equipment and instrumentation Instrument approach Instrument Flight Rules (IFR) alternate takeoff requirement for en route weather and MVFR and safety of VFR compared to Instrument flying: departure and takeoff and limitations of Instrument landing systems (ILS) approach Instrumentation. See Equipment and instrumentation International Civil Aviation Organization (ICAO) Intertropical Convergence Zone (ITCZ) Intertropical Front IRS. See Inertial Reference Systems

IRU. See Inertial Reference Units Isobars: barometric pressure connected by CAT and on weather map wind and Isolated thunderstorm ITCZ. See Intertropical Convergence Zone IVSI. See Instantaneous Vertical Speed Indicator Jet inlets Jet stream: clear air turbulence and location of above mountain waves Jetstream Journal of Aeronautical Meteorology LAMP. See Localized Aviation MOS Program Landing. See Approach and landing Landing gear retraction, rate of climb and Landing place. See also Airport fields as other than airport roads as Large-area weather Lateral Navigation (LNAV) LDS. See Lightning detection system Learning to fly weather ATC and bad en route bad to good rule good to bad rule good to good rule thunderstorms Lee waves Legal minimums Lentricular cloud Lieurance, Nieut Life cycle, of thunderstorms LIFR. See Low Instrument Flight Rules Light Sport Aircraft (LSA)

Lightning. See Electrical discharge Lightning detection system (LDS) accuracy of benefit of cloud to ground and intra-cloud detection by false reporting of improvements of lightning rate and limitations of range of spherics used by as supplement visual detection compared to Lightning Mapping Lindberg, Charles Line-Orientated Flight Training (LOFT) Line-up and wait Link Trainers Little, Dave LLWAS. See Low-Level Wind Shear Alert System LNAV. See Lateral Navigation Localized Aviation MOS Program (LAMP) LOFT. See Line-Orientated Flight Training Logical thinking Looking for pilot reports Low Instrument Flight Rules (LIFR) Low-Level Wind Shear Alert System (LLWAS) Low-pressure system Low-visibility operations Lows: large areas of occlusion and slowing down of weather map of LSA. See Light Sport Aircraft Maps. See Charts and maps Marginal Visual Flight Rules (MVFR) ceiling and IFR and as not static METAR. See Aviation Routine Weather Report

Meteorologist: asking why and if questions to at ATC big weather picture and confidence of consulting during en route weather local knowledge of NWS training private pay for satellite knowledge by MFD. See Multi Function Display Microburst: dry compared to wet indication of Midwest wind flow Missed approach autopilot failure and pilot’s practice with in thunderstorms Mode S Model Output Statistics (MOS) MODELS Moisture, instruments predicting MOS. See Model Output Statistics Mountain wave action of air and awareness of distance wavelength of flying out of jet stream above visualization of Mountains. See also Ridges altitude and ice and rotor around single peak of turbulence near VFR and wind speed increases around Multi Function Display (MFD) MVFR. See Marginal Visual Flight Rules

National Centers for Environmental Prediction (NCEP) National Lightning Detection Network National Oceanic and Atmospheric Administration (NOAA) National Transportation Safety Board (NTSB) National Weather Service (NWS) Nav Canada NCEP. See National Centers for Environmental Prediction NDB. See Nondirectional beacon NexGen. See Next Generation Air Traffic System NEXRAD. See Next Generation Radar Next Generation Air Traffic System (NexGen) Next Generation Radar (NEXRAD) aircraft presentations of ATC use of base reflectivity big weather picture from composite reflectivity of image of limitations of modes of mosaic accuracy of readings from thunderstorm areas identified by time lag of upgrades for Night flying approaching and landing horizon view and instrument lighting and thunderstorms and VFR for Nimbus clouds NOAA. See National Oceanic and Atmospheric Administration Non-precision approaches Nondirectional beacon (NDB) North Hemisphere, pressure areas in Northeast Corner, fronts in Notices to airmen (NOTAMS) NTSB. See National Transportation Safety Board NWS. See National Weather Service

Occlusions Off-airport landing Old map thoughts, valid Orographic effect ice and Outlook Briefing Overshooting landing Paper charts electronic charts compared to from newspaper PAPI. See Precision Approach Path Indicator PFD. See Primary Flight Display Pilot Weather Report (PIREPS) Pilots: action plan of air movement visualization by alert bashfulness of capability of competition among distraction exercises and electronic seduction of en route weather view of equipment and ability of experiences of feelings influencing performance of flexibility of flying basics and glider hand-flying by instinct of instrument flying proficiency of investigation by limitations of logical thinking of meteorological duties of missed approach practice by mistakes of passiveness of plane monitoring by practice by

responsibility of self-checking by sense of control needed by simulators used by spotter stress of test maneuvers for training of weather knowledge of weather philosophy of as weather-wise wind consciousness of workload of PIREPs. See Pilot Weather Report Pitot heat Planetary boundary layer (PBL) Plasticized charts Polar Continental Pollution, visibility and Power source, for instruments back up for batteries electrical failure of glass cockpit PFD screen vacuum-powered Precipitation: anti-icing needed for ATC levels of in dry climate frozen visibility and Precision Approach Path Indicator (PAPI) Preflight briefing Prefrontal squall lines avoidance of development of rules for Pressure-level charts Pressure systems, on weather maps Primary Flight Display (PFD) Primary flight group

proficiency maintenance needed for test maneuvers for Primary Weather Product Prognosis Charts Propeller anti-ice blades for fixed pitch ice and Radar. See also Airborne radar; Next Generation Radar top of thunderstorm Radiation, cooling by Radio: departure and takeoff and frequency of ice covered mast static and VFR without Rain: airborne radar detection of avoidance of turbulence and Ram Air Turbines (RAT) Range: airplane performance and departure to destination distance and fuel to alternate during holding reserve over the alternate RAOB. See Rawinsonde observation RAT. See Ram Air Turbines Rate of climb, landing gear retraction and Rawinsonde observation (RAOB) Reflectivity Reserve over the alternate Ridges: headwinds and sinks around tailwinds and turbulence near Roads, as landing place

Rotor: around mountains turbulence in visibility of Rough-air flying Route: ATC-cleared canned discontinuity Runway: alignment clearing minimum practices and surface of Runway Visibility Range (RVR) Satellite: best use of big weather picture from images shown by infrared looping of meteorologist knowledge of time stamp for VFR and water vapor display and weather movement images from Sea breeze fronts Sea level, temperature at Season, weather influenced by Sectional chart accuracy of GPS navigation compared to Self-briefing, flight planning and SIDs. See Standard Instrument Departures Significant Meteorological Information (SIGMET) Simulators: Boeing 777 media training and used by pilots for wind shear Single-axis autopilots

Single-pilot operation, in two-pilot world Sinking air Situational awareness Skew-T log-P Slaved gyro SLD. See Supercooled Large Droplets Snow: blowing off wing from clouds departure and takeoff in haze VFR in visibility in before warm fronts SPC. See Storm Prediction Center Special Weather Reports (SPECI) Spotter pilot Standard briefing Standard Instrument Departures (SIDs) Standard Terminal Arrival Routes (STAR) Standing waves STAR. See Standard Terminal Arrival Routes Stark, Howard Static, radio and Static tube Storm Prediction Center (SPC) Stormscope Stratus clouds Strike Finder Sublimation Supercooled Large Droplets (SLD) Supplementary Weather Products Surface charts Surface wind: flow fronts and gradient wind and temperature of Synopsis studying of weather information and Synoptic and Aeronautical Meteorology (Byer)

Synoptic Surface Chart Synthetic vision TAA. See Technically Advanced Aircraft TAF. See Terminal Aerodrome Forecast TAF TDA. See Terminal Aerodrome Forecast Tactical Decision Aid Tailwinds: fuel usage influenced by ridges and Takeoff. See also Departure and takeoff airport rushing IFR requirement for wind shear hazard for Taxi time: checklist read through ice and visualization and TCAS. See Traffic Collision Avoidance System TDWR. See Terminal Doppler Weather Radar Technically Advanced Aircraft (TAA) approach and landing of augmented indications dependence and charts and maps need programming verification of electronic seduction and flying basics and learning curve for flying manual practice with pilot training and programming and VFR with Technology: equipment and instrumentation influenced by thunderstorms and weather information influenced by Teletype sequences Television weather Temperature air molecules and altitude and density and dewpoint relationship with

engines and ice and inversion of at sea level surface wind and water and land differences in Terminal Aerodrome Forecast (TAF) Terminal Aerodrome Forecast Tactical Decision Aid (TAF TDA) Terminal Doppler Weather Radar (TDWR) Terminal Route Approach Control (TRACON) Terrain: adiabatic process influenced by cities influencing weather influenced by Test maneuvers: in dark with full instruments variance of Thermals Three-axis autopilot Three-needle-widths Thunderstorm detection system Thunderstorms air-mass airborne radar and airspeed and approach and landing during ATC and autopilot and avoidance of bad part of blow-off clouds of cell generation in cloud layers in clouds surrounding along cold front creation of departure and takeoff during detection of don’t race dry climate and flight diversion from

flying over frontal fronts growth of how to fly isolated kinds of landing and learning to fly weather and life cycle of lightning rate and missed approach in NEXRAD identification of night flying and prediction of prefrontal squall lines and radar top of surface winds and technology and tops of turbulence from as unstable air mass velocity of VFR and warm front and wind and wind shear and Thunderstorms, flying through almost through electrical discharge and emotions during entrance to noise during potency of radio static and Time lag, of NEXRAD Time of day, weather influenced by Tornado: flying above flying around unpredictability of Towers, VFR and

TRACON. See Terminal Route Approach Control Traffic Collision Avoidance System (TCAS) Tropopause airplane performance and CAT and charts for data passing through studying of temperature inversion and Turbulence: altitude and autopilots and convective-layer cumulus clouds and during departure and takeoff during descent flying in fog and hand-flying in high-altitude kinds of near mountains and ridges as ocean waves power changes during rain and in rotor from thunderstorms upper air velocity and Turn and bank instrument Turn coordinator Two-pilot world, single-pilot operation in Undershooting United States Weather Bureau (USWB) Universal Time Coordinated (UTC) Updraft Upper air turbulence USWB. See United States Weather Bureau UTC. See Universal Time Coordinated

VASI. See Visual Approach Slope Indicator Venturi Vertical Navigation (VNAV) Vertical speed Vertical Speed Indicator (VSI) failure of as overlooked instrument VFR. See Visual Flight Rules VGSI. See Visual GlideSlope Indicator Visibility: approach influenced by departure and takeoff and location influencing low pollution and precipitation and reduction of of rotors in snow VFR and Visual Approach Slope Indicator (VASI) Visual Flight Rules (VFR) autopilots during electronic use during emotions during en route weather and flight planning for frequency of FSS on GPS navigation and ideal arrangement for IFR compared to information lacking with limitations of minimums and mountains and navigation with near cities for night flying 180 degree turn and without radio recommendation on

responsibility of satellite imagery and sectional chart for in snow in summertime with TAA thunderstorms and on top towers and visibility and wind and Visual GlideSlope Indicator (VGSI) VNAV. See Vertical Navigation VOR navigation VOR Test Signal (VOT) Vortex, airplane performance and VOT. See VOR Test Signal VSI. See Vertical Speed Indicator WAAS. See Wide Area Augmentation System Warm front climbing into hazard of ice and retreat from sloping of snow before surface of thunderstorms and weather characteristics of wind shear and Water vapor Weather. See also Big weather picture acceptance of at airport bad, approaching landing in bad, taking off clear, good clouds influencing as complicated continuous watch over daily look at

flying influenced by along fronts fuel usage by intensity of judgment of large-area late meteorologist’s local knowledge of pilot’s knowledge of pilot’s philosophy of respect for season and time of day influencing study of terrain influencing tracking of VFR and wind influencing Weather briefing: abbreviated accuracy of for approach and landing changes in code language and example of format and code changes from FSS “IF” information and investigation and official outlook preflight self sources of synoptic television weather and vague Weather Channel Weather Depiction chart Weather information: learning where and how need for regulations on

sources for synopsis and technology influencing Weather map: information from isobars on of lows pressure systems and fronts on as snapshot Wet microburst: dry microburst compared to indication of Wide Area Augmentation System (WAAS) Wind shear airplane and approach and landing and avoidance system for from gusty winds instruments to help fly through location and forecast of overshooting and undershooting with profile of simulator for stalling from as takeoff hazard thunderstorms and warm fronts and Winds. See also Turbulence airplane performance influenced by aloft approach and landing and from bodies of water departure and takeoff and force of above friction layer in frontal system gradient gusty isobars and Midwest flow of ocean waves compared to speed of

surface flow of thunderstorms and turbulence, due to types of velocity change with height velocity of VFR and weather influenced by Windshield: fogging of ice and openings of Wings: deicers and anti-ice for hot snow blowing off Yaw damper Zippers, as fronts