FAA Instrument Rating Airplane (IRA)Weather and Weather ServicesEasy
A pilot receives a preflight briefing that includes an AIRMET Sierra for a route crossing mountainous terrain. What weather conditions does this AIRMET most likely describe?
- AExtensive mountain obscuration in clouds, precipitation, or mist and/or IFR ceilings and visibilities
- BWidespread areas of moderate turbulence below 15,000 feet MSL
- CModerate icing conditions between the freezing level and 18,000 feet MSL
- DSustained surface winds of 30 knots or greater over a large area
Show answer & explanationAnswer & explanation
Correct answer: A. Extensive mountain obscuration in clouds, precipitation, or mist and/or IFR ceilings and visibilities
AIRMET Sierra advises of IFR conditions and/or extensive mountain obscuration due to clouds, precipitation, or mist, which is especially hazardous in mountainous terrain where terrain clearance margins are already reduced.
Why the other options are wrong
- B. This describes AIRMET Tango, which covers turbulence and strong surface winds.
- C. Icing conditions are covered by AIRMET Zulu, not Sierra.
- D. Sustained strong surface winds are part of AIRMET Tango, not Sierra.
AIRMET Sierra
An AIRMET advisory for widespread IFR conditions (ceilings below 1,000 ft and/or visibility below 3 SM) and/or extensive mountain obscuration.
- Sierra = ceiling/visibility/mountain obscuration
- Tango = turbulence/strong winds
- Zulu = icing/freezing level
Memory trick: Sierra = 'See through mountains? No!' (obscuration)