For the elevator to move the nose down, what must occur?

The correct answer is that for the elevator to move the nose down, the elevator must move down. This is based on the principles of flight control surfaces and their functions.

In the case of the elevator, which is located on the horizontal stabilizer of an aircraft, its movement determines the pitch attitude of the aircraft. When the elevator deflects downward, it increases the angle of attack of the tailplane, which subsequently lowers the air pressure above the tail and increases air pressure below it. This difference in pressure creates a downward force on the tail, resulting in a nose-down attitude of the aircraft.

Understanding the dynamics of how the elevator interacts with airflow is crucial for pilots and flight engineers. When the elevator moves down, it effectively pitches the nose of the aircraft downward, making it essential for maneuvers that require descent or maintaining a stable flight path at a reduced altitude.