During flight, which control surface is primarily used to initiate a turn?

The primary control surface used to initiate a turn during flight is the aileron. Ailerons are located on the outer wings of an aircraft and are responsible for controlling the roll of the aircraft. When a pilot wants to turn, they will deflect one aileron upwards and the other downwards. This differential movement causes one wing to rise and the other to drop, resulting in the aircraft rolling toward the direction of the turn.

Using ailerons is crucial for managing the aircraft's bank angle, which is essential for effective turning. Although the elevator and rudder also play roles in overall aircraft control during a turn—elevators change pitch and the rudder aids in coordination and yaw—the ailerons are the primary surfaces used to start the actual turn by changing the aircraft's roll orientation. Flaps, on the other hand, are designed to increase lift during low-speed flight and landing, and they do not contribute to initiating turns.