Meteorology and Aviation Weather Services
What the exam tests
You must interpret aviation weather products and decide how they affect release, alternates, fuel, and in-flight monitoring. Expect METAR, SPECI, TAF, SIGMET, AIRMET, winds and temperatures aloft, PIREP, and advisories for tropical cyclones, thunderstorms, and low-level wind shear.
Core products
- METAR is an observed routine report; SPECI is a special report for significant change.
- TAF is a forecast with validity, wind, visibility, weather, cloud, and change groups such as BECMG and TEMPO.
- SIGMET warns of significant hazardous weather affecting all aircraft, such as severe turbulence, severe icing, volcanic ash, and tropical cyclones.
- AIRMET covers less severe but still significant phenomena for specified aircraft types.
- QNH is the altimeter setting that gives elevation when on the ground; QFE gives height above a reference datum.
Worked example
TAF for destination: wind 240/12, visibility 8 km, SCT030, TEMPO 1200/1600 250/25G40, 4 km TSRA, BKN012CB. The dispatcher treats the TEMPO period as a real threat: a CB with gusty winds and reduced visibility can cause a missed approach. The alternate must be forecast to meet planning minima for the arrival period, and fuel must cover a diversion. A BECMG group would indicate a lasting change, not a temporary fluctuation.
Traps
Reading TEMPO as a permanent condition or BECMG as temporary; using observed weather for a future arrival; ignoring trend groups; mixing QNH and QFE; and missing SIGMETs for volcanic ash or typhoons. In the Philippines, convective weather and typhoon tracks demand conservative alternate and fuel decisions.