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Hail size criterion for a Convective SIGMET

Remote Pilot (Part 107) practice question 21 of 25 on Weather / Effects on Performance. ACS element UA.III.B.K1h · difficulty: recall. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONA Convective SIGMET is issued for severe thunderstorms with hail at the surface of what size?

  1. AGreater than or equal to 3/4 inch in diameter
  2. BGreater than or equal to 1/2 inch in diameter
  3. CGreater than or equal to 1 inch in diameter, or any size with tornadoes
Show the answer and explanation

Correct answer: A. Greater than or equal to 3/4 inch in diameter

  • A — correct The study guide lists hail at the surface greater than or equal to 3/4 inch in diameter as one of the Convective SIGMET criteria.
  • B — incorrect The stated threshold is 3/4 inch, not 1/2 inch.
  • C — incorrect The hail threshold is 3/4 inch; tornadoes are a separate criterion and do not change the hail size.

BACKGROUND

Thunderstorms can produce large hailstones that are hazardous to an aircraft. The Convective SIGMET is an in-flight weather advisory issued for severe thunderstorms with surface winds greater than 50 knots, hail at the surface greater than or equal to 3/4 inch in diameter, or tornadoes. It is also issued to advise pilots of embedded thunderstorms, lines of thunderstorms, or thunderstorms with heavy or greater precipitation. Remote pilots can use these advisories in flight planning to avoid areas of hail.

STUDY TIP

Memorize the three Convective SIGMET numbers together: winds above 50 knots, hail of 3/4 inch or more, tornadoes.

KEY POINTS

  • Convective SIGMET hail criterion: 3/4 inch or greater at the surface.
  • Other criteria: surface winds above 50 knots, or tornadoes.
  • Large hail is one of the thunderstorm hazards named in FAA guidance.

SOURCES

  • remote_pilot_study_guide.txt ch3a "Convective Significant Meteorological Information (WST)"
  • remote_pilot_study_guide.txt ch3b "Clouds"
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MORE ON WEATHER / EFFECTS ON PERFORMANCE

SkyDrill is not affiliated with the FAA. This is an original practice item based on 14 CFR part 107, 14 CFR part 89, and the FAA Remote Pilot – Small UAS Study Guide (FAA-G-8082-22). Regulations and handbooks are revised; confirm details against the current edition.