The evolution of autopilot

In 1914, autopilot was demonstrated for the first time. This year, Airbus achieved the first ever automatic take-off. One of historic aviation’s greatest inventions has come a long way in the last century…

There were just nine years between the first powered flight in the Wright flyer and the introduction of autopilot. The need for the technology arose with the continuing sophistication of aeroplanes, leading to the ability to conduct longer flights. Relentless concentration was required to pilot early aircraft, and therefore longer flight times were tiring – occasionally fatally so. The demand for a technology to relieve the pressure from piloting was crucial. As a result, autopilot was developed to introduce an element of control on the trajectory of aeroplanes. Allowing the pilot to concentrate on broader aspects of flight, the autopilot assists in the control of the aircraft while the pilot takes care of aspects requiring judgement.

Curtiss C-2 Foatplane
The first autopilot was tested on this Curtiss Floatplane, France 1914. Image source: WikiMedia Commons

Developed by Sperry Corporation, the gyroscopic design was the first successful autopilot. Released in 1912, it incorporated a gyroscopic heading indicator and attached an attitude indicator to hydraulically operated elevators and a rudder. It utilised the inputs from several other instruments to allow an aircraft to automatically maintain a desired compass heading and altitude. Put simply, it permitted the aeroplane to fly level and straight along a given path while reducing the pilot’s workload, resulting in safer flying. Lawrence Sperry demonstrated the autopilot in France, June 1914. The technology was widely accepted as the Sperry family was known for having an impeccable credibility, so much so that Elmer Sperry (the son of Lawrence) chose to continue working on its development after the war.

Post-war development of the autopilot saw the introduction of a technology referred to as a ‘pilot’s assister’. Unlike the initial gyroscopic design, the pilot’s assister used a pneumatically-spun gyroscope to move the flight controls. The technology was introduced by the Royal Aircraft Establishment in the United Kingdom in 1930. Further developments of the first autopilot designs included improved control algorithms and hydraulic servomechanisms. The addition of increasingly complex instruments also began to allow for flight in more difficult conditions, such as through bad weather and at night.

The modern autopilot known to aviators now was introduced in the mid-20th Century. Contrary to popular belief, not all passenger aircraft of the modern day incorporate an autopilot system. Smaller and older airliners are still hand-flown on short duration flights, as the need for the technology is obsolete. A commercial airliner must contain 20 or more seats in order to warrant the installation of autopilot. There are three levels of control in modern autopilot:

  • A single-axis autopilot controls an aircraft in the roll axis only
  • A two-axis autopilot controls an aircraft in the pitch axis as well as roll, limited pitch oscillation-correcting ability. It may receive inputs from on-board radio navigation systems to provide true automatic flight guidance once the aircraft has taken off until shortly before landing; or its capabilities may lie somewhere between these two extremes
  • A three-axis autopilot adds control in the yaw axis and is not required in many small aircraft

These three levels of control are ascending in their level of vehicle control. Generally, it is only three-axis autopilot that are used in the more modern and complex aircraft. Unlike historic autopilot, the modern technology embraces computer software in order to control many aspects of the aeroplane. The process of flight can be divided into seven crucial stages: taxi, take-off, climb, cruise, descent, approach, and landing phases. Until recently, modern autopilot using computer technology has been capable of automating all these stages except taxi and take-off. However, on January 16, 2020, Airbus successfully performed the first fully automatic vision-based take-off using an Airbus Family test aircraft at Toulouse-Blagnac airport. The advanced technology of the aircraft was fully manipulated and the pilot was able to take advantage of it, while simply monitoring the performance.

Modern Autopilot
A snapshot of the many switches and instruments which make up a modern computerised autopilot. Image source: Key Archives

The advancement of autopilot from a gyroscopic-based instrument to modern day computers that are capable of manipulating phases of flight is a transition that many are in awe of. In just over 100 years, the capabilities of technology have seen pressures relieved from pilots in order to continue improving the safety of flight. But with milestones such as the first automated take-off having been achieved, where could autopilot lead aviation in the future?