Weather and Meteorology
The Weather and Meteorology domain asks you to read an observation, judge it against VFR minimums, and recognize the conditions that turn a routine flight into an emergency.
METAR and TAF
A METAR reports wind (direction true, speed, gusts), visibility in statute miles, weather, sky condition, temperature and dewpoint in Celsius, and altimeter in inches of mercury. Sky coverage runs FEW (1–2 oktas), SCT (3–4), BKN (5–7), OVC (8). The ceiling is the lowest broken or overcast layer; a scattered layer is not a ceiling. A TAF is a forecast for a stated period and is organized in time groups.
VFR minimums
Class B: 3 SM and clear of clouds. Class C, D, and Class E surface areas: 3 SM with 500 below, 1,000 above, and 2,000 horizontal. Class E above 10,000 ft MSL: 5 SM with 1,000 above, 1,000 below, and 1 SM horizontal. Class G at or below 1,200 ft AGL by day: 1 SM and clear of clouds.
Hazards and products
Density altitude, carburetor icing, structural icing, thunderstorms (give cells 20 nm), wind shear, and fog. When the temperature–dewpoint spread is 2 °C or less, fog or low stratus is likely. AIRMETs cover moderate hazards: Sierra for IFR and mountain obscuration, Tango for turbulence and strong winds, Zulu for icing. SIGMETs cover severe or extreme conditions.
Worked example
METAR: 27012G20KT 6SM -RA BKN012 OVC025 14/12 A2985. Wind 270° at 12 gusting 20 kt, 6 SM visibility, light rain, ceiling 1,200 ft broken, overcast at 2,500 ft, temperature 14 °C, dewpoint 12 °C, altimeter 29.85. In Class E below 10,000 ft the flight is legal, because 6 SM and a 1,200-ft ceiling beat the 3 SM and 1,000-ft requirement, but the 2 °C spread warns that the ceiling is likely to come down.
Traps
Counting a scattered layer as a ceiling. Missing the gust factor in the wind group. Reading a Q-group hectopascal value as inches of mercury. Treating a TAF as an observation, or assuming an AIRMET means the flight is prohibited rather than hazardous.