What is meant by 'cross-control' in aviation?

Cross-control in aviation specifically refers to the coordinated use of ailerons and rudder in opposite directions to manage adverse yaw, which is the tendency of an aircraft to yaw away from the direction of a turn due to differential lift. When a pilot initiates a turn using the ailerons, the upward deflected aileron on the rising wing decreases lift, while the downward deflected aileron on the descending wing increases lift. This differential lift can create a yawing moment toward the opposite wing, resulting in adverse yaw.

To counteract this undesirable yawing motion, the pilot uses the rudder to apply a coordinated input, which helps maintain a straight flight path during turns. This practice not only enhances the effectiveness of the ailerons but also helps maintain directional control and improves the overall stability of the aircraft during maneuvers.

Understanding cross-control is critical for pilots to perform smooth, efficient turns and maintain control of the aircraft under various flight conditions.