automatic pilot

Control device that keeps an aeroplane flying automatically on a given course at a given height and speed.

The automatic pilot contains a set of gyroscopes that provide references for the plane's course. Sensors detect when the plane deviates from this course and send signals to the control surfaces – the ailerons, elevators, and rudder – to take the appropriate action. Autopilot is also used in missiles. Most airliners cruise on automatic pilot, also called autopilot and gyropilot, for much of the time.

US business executive Lawrence Sperry first used a gyroscope in 1912 to create an artificial horizon. This entered production in 1924 and was soon linked to aircraft controls to increase stability. More gyroscopes were added later to control altitude and course. The first automatic pilot was introduced in the 1930s using pneumatic power.