CFC Meteorological Briefing & Interpretation 3 — Questions and Answers
Question 1: Which type of weather advisory covers severe icing NOT associated with thunderstorms for aircraft en route?
- AIRMET Sierra
- SIGMET
- AIRMET Zulu (Correct answer)
- Convective SIGMET
Correct answer: AIRMET Zulu
AIRMET Zulu covers moderate icing and freezing level information for general aviation aircraft.
Question 2: A Convective SIGMET is automatically issued when a line of thunderstorms is at least how long and how wide?
- 60 NM long affecting an area at least 25 miles wide (Correct answer)
- 40 NM long affecting an area at least 10 miles wide
- 100 NM long affecting an area at least 50 miles wide
- 30 NM long regardless of width
Correct answer: 60 NM long affecting an area at least 25 miles wide
A Convective SIGMET is issued for a line of thunderstorms at least 60 NM long and affecting an area at least 25 miles wide.
Question 3: A PIREP (UA) uses 'TB MDT' in the turbulence field. What does MDT indicate?
- Moderate turbulence (Correct answer)
- Moderate to light turbulence
- Moderate turbulence in deteriorating conditions
- Mandatory data threshold
Correct answer: Moderate turbulence
MDT is the standard PIREP abbreviation for moderate turbulence intensity.
Question 4: AIRMET Sierra (S) is primarily issued to warn of which condition?
- IFR conditions and/or extensive mountain obscuration (Correct answer)
- Moderate turbulence below 18,000 ft
- Moderate icing in clouds
- Sustained surface winds exceeding 30 knots
Correct answer: IFR conditions and/or extensive mountain obscuration
AIRMET Sierra warns of IFR conditions (ceilings below 1,000 ft, visibility below 3 SM) and mountain obscuration.
Question 5: How often are Convective SIGMETs issued in the contiguous US when convective activity warrants?
- Every hour at H+55 minutes, with special bulletins as needed (Correct answer)
- Every 30 minutes
- Every 2 hours with amendments as needed
- Only when requested by ATC
Correct answer: Every hour at H+55 minutes, with special bulletins as needed
Convective SIGMETs are issued at H+55 for each contiguous US area, with unscheduled special bulletins for rapidly developing situations.
Question 6: A PIREP reports 'IC RIME MDT' in the icing section. What type of ice is being reported?
- Rime ice of moderate intensity (Correct answer)
- Mixed ice requiring deicing equipment
- Rain-induced mixed icing conditions
- Reported icing in moderate cumulus
Correct answer: Rime ice of moderate intensity
RIME is the code for rime ice — a rough, opaque type that forms rapidly in supercooled water droplet clouds.
Question 7: A standard SIGMET (non-convective) is valid for up to how many hours?
- 4 hours (6 hours for hurricanes/tropical cyclones) (Correct answer)
- 2 hours
- 8 hours
- Until conditions dissipate
Correct answer: 4 hours (6 hours for hurricanes/tropical cyclones)
Non-convective SIGMETs are valid for up to 4 hours, or 6 hours when issued for tropical cyclones.
CFC Meteorological Briefing & Interpretation 3
Which type of weather advisory covers severe icing NOT associated with thunderstorms for aircraft en route?