What is the primary function of an aileron in an aircraft?

The primary function of an aileron in an aircraft is to change the roll of the aircraft. Ailerons are hinged surfaces located on the trailing edge of each wing and are used to control the aircraft's lateral movement, allowing it to tilt side to side. When the pilot moves the control stick or yoke left or right, one aileron deflects upward while the other deflects downward. This creates unequal lift on the wings, causing the aircraft to roll in the desired direction. This motion is critical for maneuvering during flight, especially when turning.

In contrast, the other choices describe control functions managed by different flight surfaces: increasing lift and drag pertains to flaps; pitch control relates to the elevators located on the tail; and yaw is controlled by the rudder, which is also situated on the tail and affects the aircraft's direction about its vertical axis. Understanding the specific role of each control surface is vital for pilots to accurately navigate and maneuver their aircraft.