FAA Flight Instructor Airplane (FIA)Aircraft Systems and InstrumentsEasy
A student pilot notices during preflight that the pitot heat switch is illuminated but the pitot tube feels only slightly warm to the touch. The CFI explains that pitot heat is designed primarily to prevent which condition from affecting airspeed indications?
- AExcessive ram air pressure during high-speed descents
- BMoisture freezing inside the airspeed indicator instrument case itself
- CIce formation blocking the pitot tube opening and drain hole during flight in visible moisture
- DCondensation buildup inside the static system during ground operations
Show answer & explanationAnswer & explanation
Correct answer: C. Ice formation blocking the pitot tube opening and drain hole during flight in visible moisture
Pitot heat is an electrically heated element that prevents ice from forming on and blocking the pitot tube opening and drain hole during flight in visible moisture at or near freezing temperatures, which would otherwise cause erroneous or lost airspeed indications.
Why the other options are wrong
- A. Pitot heat has no effect on ram air pressure.
- B. The instrument case itself is not heated by pitot heat.
- D. Static system icing is addressed by alternate static source, not pitot heat.
Pitot Heat System
An electrically heated pitot tube element that prevents ice from blocking the pitot opening and drain hole in icing conditions.
- Controlled by a cockpit switch, powered by the electrical system
- Protects only the pitot tube, not static ports (unless heated static ports installed)
- Should be checked for warmth during preflight and used anytime in visible moisture near freezing
Memory trick: Hot pitot, no blocked shot (of air pressure)