FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

The correct answer is A. Elevator. In an autopilot system, the elevator channel is responsible for detecting and controlling changes in the pitch attitude of an aircraft. The elevator is the primary control surface that is used to pitch the nose of the aircraft up or down, affecting the aircraft's pitch attitude. The autopilot system uses the elevator channel to make adjustments to maintain the desired pitch attitude set by the pilot or the autopilot system itself.

Options B, C, and D are incorrect because the aileron is responsible for roll control, the rudder is responsible for yaw control, and the throttle is responsible for controlling the engine power, none of which directly relate to detecting changes in pitch attitude.