Which control surface is responsible for pitch movement and longitudinal stability?

The elevator is the control surface primarily responsible for pitch movement and maintaining longitudinal stability in an aircraft. It is typically located at the rear of the aircraft, either on the horizontal stabilizer or as part of a stabilator. When the elevator moves up or down, it changes the angle of attack of the tail section, which directly influences the pitch of the aircraft, causing it to climb or descend.

Longitudinal stability is crucial for an aircraft's ability to maintain a consistent flight path in the forward and backward direction. By adjusting the elevator, pilots can effectively control the center of gravity's relationship to the lift generated by the wings, ensuring smoother flight and more controlled maneuvers. This is essential for achieving balance and stability during various phases of flight, such as takeoff, cruising, and landing.

While other control surfaces like the rudder and ailerons play important roles in directional control and roll stability, they do not directly influence pitch movement in the same way that the elevator does. The stabilator can function similarly to an elevator, but it is not as commonly referenced for traditional aircraft designs. Thus, the elevator is the definitive answer for controlling pitch and maintaining longitudinal stability.