The Weather Never Sleeps

The reason that pilots need to learn about weather is straightforward. They need to be able to make sound decisions about whether the weather is likely to be too bad for them or their airplane to handle. Discovering exactly what weather knowledge you need to make sound go/no-go decisions is anything but straightforward.

A second reason pilots have to learn at least a little about weather is that FAA knowledge tests for certificates and ratings include weather questions. You've got to pass the FAA test before you can get into an airplane and demonstrate your skills to an examiner. Unfortunately, the second reason - passing an FAA test - often drives how flight instructors select the kinds of things pilots learn about weather.

This is unfortunate because the tests don't ask questions about some important aspects of aviation weather. Instead of encouraging pilots to learn what they'll need to know as they begin making preflight and in-flight weather decisions, the FAA test questions require them to learn such things as memorizing a formula that no one uses in real life.

Many FAA test questions, says a 1995 National Research Council report, "focus on the ability of students to decipher the abbreviations used in standard weather messages instead of their ability to use weather information to make safe operational decisions regarding the weather. As a result, it is not uncommon for general aviation pilots to ask flight service specialists if it's safe to fly, even though it is the pilot's responsibility to make that determination."

The report, Aviation Weather Services, was written by a panel that included experienced pilots and atmospheric scientists, including some members who are both. It looked at all aviation weather forecasting, how pilots obtain and use weather information, and weather training that pilots and others receive. In its look at training, the report argued that "... traditional methods of teaching weather concepts during initial and recurrent pilot training do not always adequately prepare pilots to make consistently safe operational decisions."

One reason for this failure is: "The classroom training of many student pilots is focused on passing the FAA's (Federal Aviation Administration's) written examination." This complaint wasn't new. In 1986 the National Center for Atmospheric Research Aviation Weather Forecasting Task Force described the FAA knowledge test weather questions as "simplistic, vague, and qualitative" and said they fail to evaluate students' "ability to assess quantitatively the impact (of weather) on aircraft operations."

Yet, the weather questions on the 1998 edition of the FAA's private pilot and instrument pilot tests are virtually the same as those on the 1985 and earlier versions of the FAA's test. The biggest changes in weather questions since the 1980s are in the questions that require deciphering weather reports and forecasts. These had to be changed because METAR reports and Terminal Aerodrome Forecasts (TAFs) replaced the old reports and forecasts.

In the real world of flying, pilots rarely have to translate the codes. If they use the Direct User Access Terminal System (DUATS) to obtain weather briefings via computer, they can have the messages translated. If they visit or call an FAA flight service station, a trained weather briefer will do the translating.

Because the FAA doesn't seem likely to heed the advice of the experts who would like to improve the knowledge exams, it's up to instructors and students to find out what pilots really need to know about the weather. As a start on this task, let's look at the questions on the FAA's private and recreational pilot tests to see how they can send an instructor or student off on the wrong course toward mastering practical aviation meteorology.

Anyone who looks at weather presentations on television notices the letters L for low pressure centers, which are storms, and H for high pressure centers on the map. They must be important because meteorologists make so much of them, especially their movement.

The formation, growth, movement, and weakening of low-pressure and high-pressure areas are a key to understanding the weather across the middle latitudes, which includes all of the U.S. except Hawaii. Yet, the FAA's private pilot test does not include any questions about low- and high-pressure centers.

Pilots need to know how storm systems affect the general patterns of the weather over periods of hours to days. Time spent mastering the parts of any current meteorology textbook covering extratropical cyclones is time well spent. It's also a good idea to watch television weather or obtain complete weather reports from the Internet and compare the information with what the weather actually does.

The private pilot examination asks no questions about upper-atmospheric weather. Pilots should be familiar with the flow of winds above the ground and how they affect the weather. They also should know about upper-air highs and lows.

Air stability and instability are extremely important in predicting what kinds of clouds and precipitation are likely and whether the air is likely to be smooth or turbulent. The FAA private pilot questions on this topic aren't bad. Anyone who can answer them all - because they know the subject, not because they memorized the answers - has a fair grasp of the topic.

But the private pilot questions also require a pilot to know questionable facts - for example, that you can, in theory, find the approximate base of cumulus clouds above the ground by subtracting the surface dew point from the surface temperature, dividing the result by 4.4 and multiplying the answer by 1,000. Knowing this formula is of no use in flying. Real pilots obtain information about the forecast height of clouds above the ground by consulting weather forecasts.

Learning enough about air stability to answer exam questions has one pitfall.

Several questions require you to know that stratus clouds, steady precipitation, and smooth air are associated with stable air while cumulus clouds, showery precipitation and turbulence come with unstable air. All of this is true enough. But just saying this could leave a student with the idea that a sharp divide exists between stable and unstable air and the conditions associated with them. The student quickly learns by flying and by even looking at the sky that this isn't necessarily so. Many times you see both flat, stratus clouds and lumpy cumulus clouds in the air together. This happens, of course, because different layers of the air can have differing degrees of stability. Furthermore, the dividing line between stable and unstable air isn't always sharp. One can fade into the other.

Questions on the FAA tests are based almost entirely on FAA advisory circulars; Aviation Weather, which covers basic meteorology; and Aviation Weather Services, which describes the various kinds of weather reports and forecasts.

Aviation Weather represents essentially a 1970s' knowledge of meteorology. Its shortcomings as a source of weather questions shows up in exam questions about thunderstorms. Any in-depth discussion of spring and summer weather in many parts of the U.S. today is likely to include the terms "super cell," "mesocyclone," "Doppler radar," "multi-cell storm," "outflow boundary," and "mesoscale convective complex." Often you hear television weathercasters use such terms. Yet, none of these important weather phenomena appear in Aviation Weather or on FAA exams.

Although exam questions miss many important concepts that pilots need to know about, some exam questions require you to know things that few pilots will ever use. For example, one question says, "Low-level turbulence can occur and icing can become hazardous in which type of fog? A - Rain-induced fog; B - Upslope fog; C - Steam fog. The answer is almost surely "C" because it's almost a direct quotation from the "Arctic Weather" chapter of Aviation Weather.

Steam fog forms when cold air flows over relatively warm water. The only kind of steam fog that most pilots will ever see up close is the small wisps that form on fall days when cold air flows over ponds, lakes and rivers. It's hardly ever deep enough for an airplane to fly into. To fly into the kind of steam fog the question describes would require flying low and far out over one of the Great Lakes in early winter, when cold air blasts down from Canada to create "lake-effect" blizzards along the southern and eastern sides of the lakes.

By the way, a test question or two about lake-effect snow would be a good idea. In the U.S. it occurs mostly near the Great Lakes and sometimes near the Great Salt Lake. Mentioning it in pilot training could alert pilots from other parts of the country that lake-effect snow is something they ought to know about if they ever fly to the Great Lakes region. In fact, a few questions about weather in different parts of the country, such as over the western deserts or in mountains, would be a real service to pilots from other parts of the country. An airplane will take you anywhere, including regions where you'll encounter weather you've never seen before.

The private pilot test has as many questions about reading coded reports and weather maps as it does on basic weather. Pilots obviously need to understand basic weather reports and forecasts, but a more realistic test would have more questions based on plain-English briefing texts than on coded reports that few of today's pilots ever have to try to read.

Also, questions based on the radar maps many pilots see on the Internet or on television should be added to those based on the Radar Summary Chart, which few pilots ever see. Any pilot who has access to the World Wide Web can call up charts such as the U.S. Radar Summary from Intellicast at www.intellicast.com/weather/usa/radsum/.

Finding a radar summary chart on the Web is a challenge that probably isn't worth the time it would take. For a pilot who has a basic understanding of meteorology and weather radar, the Intellicast chart has more information than the radar summary chart. And, it's almost sure to be more current.

If the FAA's tests aren't a good guide to a pilot's weather education, what is?

Students in almost all college or university flight training programs don't have to worry about this question. Most programs require meteorology courses that lay a good foundation for continuing to learn about weather over a long flying career.

For other students and their instructors, the best starting points are up-to-date books on aviation weather and meteorology in general. Two aviation weather books worth obtaining are:

Peter F. Lester, Aviation Weather, published by Jeppesen Sanderson, Inc., Englewood, Co., in 1995. If you order this book, make sure you don't get the FAA's Aviation Weather. Lester's book has enough basic science to help you understand what's going on. It is strong on aviation weather hazards.

Terry T. Lankford, Pilot's Guide to Weather Reports, Forecasts, and Flight Planning, 2nd edition, published by The Tab Books Division of McGraw-Hill, Inc. in 1995. Lankford's book does a much better job of helping pilots understand reports and forecasts than Aviation Weather Services. In addition, Lankford explains quite a bit of meteorology as he shows you how to understand written material and charts. For example, he includes a good discussion of upper air weather systems to help you understand upper air charts.

The right text books are only a start. Students should become weather watchers. Even when you aren't flying you should obtain weather reports and forecasts, try to decide whether you would want to fly that day, and then see how the weather actually turns out.

Instructors could incorporate weather discussion into part of each pre-flight and post-flight briefing. Even if the lesson is going to be an hour in the pattern doing touch-and-go landings and takeoffs, the instructor could have a student obtain a weather briefing and discuss it with the instructor.

Flight schools or individual instructors also could write their own weather exam questions that address the real-world concerns of their students. These questions should come from information found in up-to-date text books and from the experiences of instructors and their students.

For example, any instructor who's had the experience of sending a student off on a cross-country solo flight that ended prematurely because of unexpected bad weather could save the preflight forecasts and information about what the weather actually did. Such a scenario could be the basis for a good discussion of the real-world problems of coping with the weather.

Student pilots who learn what they really need to know about the weather should have no problem with the written exam even if they do have to waste a little time learning things such as the formula for the base of cumulus clouds. And when they do take to the air, they'll be better prepared than students who let the exam set their weather curriculum.