We’ve been running the 10 question daily quizzes on PrepareToTest for the various exams and as part of this we track the overall performance on each question - how many times it was attempted, how many times it was answered correctly, which answers were selected, etc. By looking at the scores its very obvious when people are having problems with a particular question or topic. Based on this Im going to periodically write up an explanation for particularly troublesome questions. Today’s Private Pilot quiz had a good example related to Convective Sigmets.
Private question 3495 had the following results:
“What is indicated when a current CONVECTIVE SIGMET forecasts thunderstorms?”
A - Moderate thunderstorms covering 30 percent of the area. (7 people)
B - Moderate or severe turbulence. (6 people)
C - Thunderstorms obscured by massive cloud layers. (1 person)
14 people answered the question but only one person got it right - the correct answer is C. When a Convective SIGMET forecasts thunderstorms this can be due to any of a number of situations:
- Severe thunderstorms due to: surface winds greater than 50kts, or Hail at the surface greater than or equal to 3/4″ diameter, or tornadoes.
- Embedded thunderstorms (i.e. thunderstorms obscured by massive cloud layers)
- A line of thunderstorms
- Thunderstorms producing precipitation greater than or equal to heavy precipitation affecting 40% or more of an area at least 3,000 square miles
Answer A is incorrect because Convective SIGMETS are issued when there are thunderstorms producing heavy or stronger precipitation affecting 40% or more of an area, not 30%. Answer B is incorrect because any Convective SIGMET implies severe or greater turbulence, not moderate or severe turbulence. See AIM 7-1-6 part d for a more complete description of Convective SIGMETs and when they are issued, try the Aviation Digital Data Service (ADDS) for a look at the current AIRMETs and SIGMETS.
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