FAA Airline Transport Pilot (ATM)Meteorology and Weather ServicesEasy
A dispatcher planning a flight through mountainous terrain notes that an AIRMET Sierra is currently in effect for the route. What hazard does this advisory primarily indicate?
- AWidespread mountain obscuration in clouds, precipitation, or mist
- BModerate turbulence below 18,000 feet MSL
- CSustained surface winds of 30 knots or greater
- DModerate icing and freezing levels
Show answer & explanationAnswer & explanation
Correct answer: A. Widespread mountain obscuration in clouds, precipitation, or mist
AIRMET Sierra advises of IFR conditions and/or widespread mountain obscuration due to clouds, precipitation, mist, or haze. AIRMET Tango covers turbulence and sustained surface winds, while AIRMET Zulu covers icing and freezing levels.
Why the other options are wrong
- B. Turbulence is covered by AIRMET Tango, not Sierra.
- C. Sustained surface winds are also part of AIRMET Tango.
- D. Icing is covered by AIRMET Zulu, not Sierra.
AIRMET Sierra
An AIRMET issued for widespread IFR conditions (ceilings below 1,000 ft and/or visibility below 3 miles) and/or extensive mountain obscuration.
- Sierra = IFR/mountain obscuration
- Tango = turbulence and strong surface winds
- Zulu = icing and freezing level
Memory trick: S-T-Z: Sierra=Sky obscured, Tango=Turbulence, Zulu=frost/ice