Meteorological Observations, Reports and Forecast Products
Observations
Candidates must decode METAR and SPECI. Key groups: wind (direction/speed/gusts, VRB), visibility (metres), runway visual range (RVR), present weather (intensity, descriptor, precipitation, obscuration), cloud (amount FEW/SCT/BKN/OVC and height in hundreds of feet), temperature/dewpoint, QNH, and trend. CAVOK means visibility ≥10 km, no cloud below 5000 ft or below the highest MSA, and no significant weather. TAF is the aerodrome forecast with validity period and change groups (BECMG, TEMPO, FM).
Other products
SIGMET warns of severe weather (thunderstorms, icing, turbulence, volcanic ash, tropical cyclones); AIRMET covers lesser hazards. PIREPs give pilot reports. GAMET and area forecasts cover en-route conditions. METAR trends and TAF change groups must be interpreted correctly: BECMG means gradual change, TEMPO temporary fluctuations, FM an abrupt change.
Traps
Questions confuse BKN and OVC, misread cloud height (hundreds of feet), or confuse BECMG with TEMPO. Remember CAVOK excludes significant weather and low cloud. Wind direction is true in TAF and METAR (magnetic in ATIS and tower reports).
Worked example
METAR: 24015G25KT 9999 SCT030 BKN080 18/12 Q1015. Wind 240° at 15 kt gusting 25, visibility ≥10 km, scattered cloud at 3000 ft, broken at 8000 ft, temperature 18°C, dewpoint 12°C, QNH 1015 hPa. Spread 6°C suggests no fog risk.
Rule of thumb
Cloud height in METAR/TAF is in hundreds of feet: BKN080 = 8000 ft.