Which PROBE/WINDOW HEAT pushbutton position will only activate the Probe and Window heat if at least one engine is running or the aircraft is in flight?

Which PROBE/WINDOW HEAT pushbutton position will only activate the Probe and Window heat if at least one engine is running or the aircraft is in flight?

• A. ON
• B. OFF
• C. MANUAL
• D. AUTO

Answer: (D)

In AUTO, the Probe and Window heat are controlled by the aircraft’s operating state. The system automatically turns the heaters on only when it’s actually needed—when at least one engine is running or the aircraft is in flight. That means during flight, or when the engines are powering the aircraft, heat is applied to protect the probes and windshield from ice and frost, ensuring accurate readings and clear visibility. On the ground with no engines running, the heaters stay off to save electrical power and reduce wear, since the immediate icing risk is lower and power is limited. Choosing ON would keep heat on all the time, wasting electrical power and potentially stressing components in safe ground conditions. OFF disables heating entirely. MANUAL requires pilot intervention regardless of flight state. AUTO provides automatic protection exactly when the sensors and windows need it during flight or engine operation.

In AUTO, the Probe and Window heat are controlled by the aircraft’s operating state. The system automatically turns the heaters on only when it’s actually needed—when at least one engine is running or the aircraft is in flight. That means during flight, or when the engines are powering the aircraft, heat is applied to protect the probes and windshield from ice and frost, ensuring accurate readings and clear visibility. On the ground with no engines running, the heaters stay off to save electrical power and reduce wear, since the immediate icing risk is lower and power is limited.

Choosing ON would keep heat on all the time, wasting electrical power and potentially stressing components in safe ground conditions. OFF disables heating entirely. MANUAL requires pilot intervention regardless of flight state. AUTO provides automatic protection exactly when the sensors and windows need it during flight or engine operation.