Aircraft systems and instrumentsQuestion 595 of 934

What causes carburetor ice to form?

  1. Cold fuel from the tank cools the carburetor body
  2. Friction of the air against the carburetor walls
  3. Compression of the air by the propeller blades
  4. Fuel vaporization and venturi pressure drop cool the air
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Correct answer: Fuel vaporization and venturi pressure drop cool the air

The sharp temperature drop can freeze water vapor on the inside of the carburetor, including the throttle valve.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Induction Systems — Carburetor Icing, page 169

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Questions last reviewed: 18 October 2026