If the flap indicator fails, how can flap extension be confirmed?

The correct answer indicates that flap extension can be confirmed by observing a slight nose-up tendency of the aircraft. This phenomenon occurs because extending the flaps alters the aerodynamic characteristics of the aircraft, resulting in increased lift at lower speeds, which typically causes the nose of the aircraft to pitch up slightly. Pilots are trained to recognize this behavioral change as an indirect confirmation that the flaps have been deployed.

In general aviation and flight training, understanding the aircraft's response to flap extension is crucial, especially in scenarios where direct indicators or gauges might fail. The subtle shift in the aircraft’s attitude can help pilots maintain situational awareness and ensure safety during critical phases of flight, such as approach and landing.

While manual checks and secondary indicator gauges are indeed options when addressing an indicator failure, they aren't as immediately actionable as recognizing the aircraft's behavior through its pitch attitude. Listening for changes in engine sound is not a reliable method for confirming flap extension, as those sounds can be influenced by various other factors unrelated to flap position. Hence, the confirmation through the aircraft's nose attitude is the most practical immediate response to flap indicator failure.