The Weather Briefing
Check these elements for a good preflight decision
By Jack Williams
Imagine that soon after earning your private pilot certificate you're taking a friend—who knows nothing about aviation—for an airplane ride.
Both of you are belted into a Cessna 152 and you've just started going through the prestart checklist when your friend says, "I thought you have a pilot's license. Why are you reading how to fly?"
Making a quick recovery from your surprise, you tell your friend that aviators use checklists to ensure important tasks aren't missed during busy times. You point out that even the most experienced airline crews use them.
What you tell your friend about the virtues of aircraft checklists applies just as much to obtaining a preflight weather briefing as it does to what you do while you're in the airplane. The federal aviation regulations require you to learn about the weather that might affect any flight. A weather briefing checklist ensures you don't miss any important information while doing this.
The best way to obtain a briefing is to call or visit an FAA Flight Service Station (FSS). The briefers employed there are trained to help pilots obtain and understand weather information. Unless you ask for something different—more about this later—the FSS briefer will give you a standard briefing. The items covered in such a briefing make a perfect checklist for any time you obtain a briefing, whether it's from a flight service station, an online service such as DUAT, or any other source.
Let's take a look at the list of items to check. (The numbered paragraphs below are those that together comprise a standard briefing as defined in the FAA's Aviation Weather Services advisory circular.)
- Adverse conditions. You begin by learning about conditions—either existing or forecast—that might make you want to cancel the planned flight. If things look really bad, you can call off the flight before you and the briefer invest a lot of time.
The quickest way to discover whether any dangerous weather is likely to affect your flight is to see if any National Weather Service sigmets or airmets have been issued for where you plan to fly. A sigmet is an advisory for weather that could be dangerous to any aircraft.
Convective sigmets alert you to the dangers of thunderstorms, while the National Weather Service issues other sigmets for conditions such as severe turbulence or icing. An airmet alerts pilots to weather dangers that are more likely to affect smaller aircraft than large ones, such as moderate turbulence or icing, and widespread areas of low clouds or poor visibility.
- VFR flight not recommended. At this stage, the briefer could tell you, "Visual flight rules [VFR] flight is not recommended" if you are planning such a flight. This item reminds both briefers and pilots to consider whether the proposed VFR flight is a good idea.
If a briefer tells you "VFR flight not recommended," it does not mean regulations forbid the flight. If you think that your flying expertise is adequate to make the flight safely and legally, you can continue the briefing. But, "VFR not recommended" should prompt you to take a very close look at the weather while making sure you don't kid yourself about either your abilities or the atmospheric conditions (see "Aviation Speak: VFR not recommended," September 2003 AOPA Flight Training). A go/no-go flight decision should depend on a brutally honest analysis of your experience and ability to handle any weather you might encounter.
- Synopsis. This is a description of the general weather situation, including the kinds, locations, and movements of any weather systems that might affect your flight. With this big weather picture in mind, you're ready to take a more detailed look at what the weather is doing now and expected to do during your flight.
- Current conditions. Even though you might not expect to arrive at your destination for two or three hours, you need to find out what the weather is doing now at your destination, at your takeoff point, and along your route. Knowing what the weather is doing now will help you understand how it could change by the time you arrive at your destination, and help you to recognize if it is changing.
The regular, hourly METAR weather reports from your departure and destination airports—and airports along your route—will give you a good idea of what's happening on the ground. Satellite and radar images will help you to round out the picture.
Now you're ready to see what forecasters think will be happening along your route at least an hour or two before and after you expect to take off, pass weather-reporting stations along the way, and land. In fact, as you look at all of the forecasts to follow, you should be asking, "When is the weather forecast to turn into something I'd rather see from the ground than from my airplane?" For example, if thunderstorms are forecast at your destination three hours after you expect to arrive, you should be on the lookout for signs, such as nasty-looking clouds ahead of you, that the weather is running ahead of schedule.
- En route forecast. Here you are looking for a general picture of the weather along your route of flight. Text forecasts that will help are area forecasts, which describe general conditions over large areas of the United States, as well as route forecasts issued for routes between various airports. Weather maps known as significant weather prognotic (prog) charts give you a general picture of what's forecast to be happening at the surface and aloft.
- Destination forecast. Here you are looking for a text product known as a terminal aerodrome forecast (TAF) for your destination. These give you the anticipated conditions that could affect aviation, broken down by time periods.
- Winds and temperatures aloft. You need the information about wind speeds and directions to help you pick the best altitude at which to fly and to calculate how long the trip should take. Temperature-aloft information is also used in flight calculations, as well as to determine the freezing level.
- Notams. Notices to airmen, or notams, refer to information from the FAA about a host of things that could be important for you to know. For instance, a notam might be your early warning about a closed runway or taxiway at your destination airport, or about a radio navigation beacon that's shut down for repairs. Even more important, a notam can alert you to the sudden appearance of a temporary flight restriction along your route—a critical concern for pilots today.
- Air traffic control delays. Here the briefer will tell you about any air traffic delays that might affect your flight.
- Request for pireps. A pirep is an in-flight pilot report of weather conditions encountered aloft. The FAA, the National Weather Service, and aviation organizations such as the AOPA Air Safety Foundation are encouraging pilots to file pireps because they help both other pilots and weather forecasters (see "The Weather Never Sleeps: Pirep plea," January 2003 AOPA Flight Training magazine). When you read a pirep, be sure to check the date and time the report was made—pireps can be hours old. Obviously, the more current the pireps, the better the information. If you're uncomfortable making pireps, brush up with the AOPA Air Safety Foundation's free SkySpotter online course.
- EFAS reminder. The En route Flight Advisory Service, usually called flight watch, is a radio service (122.0 MHz) that allows pilots to obtain updated weather information from specially trained flight service briefers and submit pilot reports. After you take off, you should use it to make sure you learn about any changes in weather conditions or forecasts that might affect your flight.
- Other information. Before finishing, you can ask the briefer about things such as military activity in the area where you plan to fly.
In addition to a standard briefing, you can request an outlook briefing when your departure time is more than six hours away. Such a briefing might help you evaluate your chances of making the flight before planning it out.
You can also ask for an abbreviated briefing if you want only specific kinds of information, such as a terminal forecast. Don't think of an abbreviated briefing as a shortcut to save time, however; you could miss important information. But, if a couple of hours have gone by since you received a standard briefing, an abbreviated briefing is a good way to see if anything has changed.
You can get a good idea of what's involved in a standard briefing on the Web by going to the National Weather Service's Aviation Weather Center Web site. On the left side of the page you'll see a link to "Standard Briefing." On this page you'll find links to the various products needed for such a briefing.
Using the standard briefing "checklist" is a good way to ensure you won't have to answer passenger questions such as, "Shouldn't you have known low clouds would keep us from making it to that great airport restaurant?"
Jack Williams is weather editor of usatoday.com. An instrument-rated private pilot, he is the author of The USA Today Weather Book and The Complete Idiot's Guide to the Arctic and Antarctic, and co-author with Bob Sheets of Hurricane Watch: Forecasting the Deadliest Storms on Earth.