Stability Augmentation System

An autopilot is a system used to control the trajectory of an aircraft without constant 'hands-on' control by a human operator being required. Autopilots do not replace a human operator, but assist them in controlling the aircraft, allowing them to focus on broader aspects of operation, such as monitoring the trajectory, weather and systems.

The autopilot system on airplanes is sometimes colloquially referred to as "George".

In the early days of aviation, aircraft required the continuous attention of a pilot in order to fly safely. As aircraft range increased allowing flights of many hours, the constant attention led to serious fatigue. An autopilot is designed to perform some of the tasks of the pilot.

The first aircraft autopilot was developed by Sperry Corporation in 1912. The autopilot connected a gyroscopic heading indicator and attitude indicator to hydraulically operated elevators and rudder. (Ailerons were not connected as wing dihedral was counted upon to produce the necessary roll stability.) It permitted the aircraft to fly straight and level on a compass course without a pilot's attention, greatly reducing the pilot's workload.

Lawrence Sperry (the son of famous inventor Elmer Sperry) demonstrated it in 1914 at an aviation safety contest held in Paris. At the contest, Sperry demonstrated the credibility of the invention by flying the aircraft with his hands away from the controls and visible to onlookers of the contest. Elmer Sperry Jr., the son of Lawrence Sperry, and Capt Shiras continued work after the war on the same autopilot, and in 1930 they tested a more compact and reliable autopilot which kept a US Army Air Corps aircraft on a true heading and altitude for three hours.

In 1930, the Royal Aircraft Establishment in the United Kingdom developed an autopilot called a pilots' assister that used a pneumatically-spun gyroscope to move the flight controls.

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Wikipedia