Meteorological Information, Reports, Forecasts and In-Flight Services
What the exam tests
This domain tests decoding and using METAR, SPECI, TAF, trends, warnings and in-flight meteorological services.
Core rules
- METAR is a routine aerodrome observation; SPECI is a special observation. TAF is an aerodrome forecast, with validity, wind, visibility, cloud, temperature and pressure groups, and TEMPO/BECMG change indicators.
- Wind is normally true in forecasts and reports unless stated; visibility is in metres or kilometres; cloud heights are above aerodrome elevation.
- QNH is the altimeter setting that gives elevation; QFE gives height above a datum; flight levels use standard pressure 1013.25 hPa.
- AIRMET/SIGMET warn of significant en-route weather; PIREP is a pilot report; ATIS/VOLMET provide broadcast information.
Worked example
METAR: wind 120° at 15 kt, visibility 10 km or more, scattered cloud at 3,000 ft, temperature 25°C, dew point 15°C, QNH 1013 hPa. The 10°C spread suggests a cloud base near 4,000 ft, consistent with scattered cloud at 3,000 ft. The QNH means setting 1013 gives aerodrome elevation on the ground. The reasoning separates each group rather than reading the whole report as a sentence.
Traps
Using local time instead of UTC; treating TEMPO as a permanent change; confusing QNH and QFE; reading cloud height as AMSL.