Meteorology and Weather Services
Meteorology questions test decoding reports and forecasts, then applying them to a light, wind-sensitive rotorcraft. Expect METAR and TAF decoding, AIRMET and SIGMET interpretation, wind and density-altitude reasoning, and recognition of hazards such as wind shear, turbulence, and convection.
Reports and forecasts
- METAR: wind, visibility, weather, sky cover, temperature/dew point, altimeter. Example: KJXN 121953Z 27015G22KT 10SM SCT035 18/09 A3002 means wind 270° at 15 gusting 22 kt, 10 statute miles visibility, scattered clouds at 3,500 ft AGL, temperature 18 °C, dew point 9 °C, altimeter 30.02 inHg.
- TAF: valid period in Zulu time with FM, TEMPO, and BECMG change groups.
- PIREPs report actual conditions aloft, including turbulence and icing.
- AIRMETs cover moderate hazards: Sierra for IFR and mountain obscuration, Tango for turbulence and strong surface winds, Zulu for icing. SIGMETs cover severe or extreme conditions.
- Winds aloft forecasts give direction, speed, and temperature at altitude.
Flight categories
VFR ceilings above 3,000 ft and visibility above 5 sm; MVFR 1,000–3,000 ft or 3–5 sm; IFR 500–1,000 ft or 1–3 sm; LIFR below 500 ft or below 1 sm.
Gyroplane sensitivities
A gyroplane cannot hover, so strong or gusty wind complicates the landing rollout and can push a slow machine sideways. Low-level turbulence, dust devils, and thermals produce sharp pitch changes, and rotor RPM responds quickly, so keep a margin above minimum speed. Density altitude hurts rotor and engine performance at the same time.
Worked example
Wind 270° at 15 kt, runway 240°. The angle is 30°, so crosswind = 15 × sin 30° = 7.5 kt and headwind = 15 × cos 30° = 13 kt. A 7.5 kt crosswind is manageable in most trainers; but with gusts to 22 kt the gust crosswind reaches about 11 kt, and a different runway may be wiser.
Traps
Confusing AGL and MSL heights in a TAF; forgetting times are Zulu; treating an AIRMET as a prohibition; and ignoring the gust spread, which matters more to a light gyroplane than the steady wind.