METEOROLOGY FLIGHT PLANNING
The FA consists of two sections, the synopsis and VFR clouds/weather. Additionally every FA
will always have the following three lines listed after the heading, before the synopsis and
SEE AIRMET SIERRA FOR IFR CONDS AND MTN OBSCN.
TSTMS IMPLY SVR OR GTYR TURB SVR ICG LLWS AND IFR CONDS.
NON MSL HGTS NOTED BY AGL OR CIG.
A six-hour categorical outlook follows each 12-hour specific clouds/weather forecast. At a
minimum, the category of the expected prevailing conditionIFR, MVFR, or VFRand the cause
of the condition is stated in the outlook. These categorical terms correspond with those used
elsewhere (such as the Weather Depiction Chart, Chapter Two), and they are not used otherwise
in the FA.
The FA is generally straightforward and easy to understand. Each uses only approved
abbreviations and contractions, and the weather and obstructions to vision abbreviations are the
same as those used in METARs. All times in the body of the forecasts are stated in two digits
using whole hours of UTC and qualifiers such as BY, UNTIL, AFTER, THRU, and BYD
(beyond). All distances are in nautical miles, speeds in knots, and visibilities in statute miles.
Locations are described by using geographical locations, two-letter state and Great Lakes
identifiers, and three-letter location identifiers. The altitude reference is MSL unless otherwise
noted by the terms AGL or ceiling (CIG).
IN-FLIGHT WEATHER ADVISORIES
The Aviation In-Flight Weather Advisory program provides information for pilots of en route
aircraft via voice communications of the possibility of encountering weather phenomenawhich
may not have been forecast at the time of the preflight briefing of sufficient extent and/or intensity
as to be potentially hazardous to aircraft operations. It is intended to serve the needs of both
civilian and military aviation as a "common-system" aviation weather safety program.
There are five types of in-flight messages:
Severe Weather Forecast Alerts (AWW)
Convective SIGMETs (WST)
Non-Convective SIGMETs (WS)
Center Weather Advisories (CWA)
SEVERE WEATHER WATCHES, MILITARY ADVISORIES, AND PIREPS