Do you know the difference between autopilot and flight director? In the early days of aviation, airplanes only featured manual controls. It wasn’t until 1912 when autopilot was invented, which automated many basic flight controls. In the 1950s, however, flight director was introduced to further assist pilots.
What Is Autopilot?
Also known as Automatic Flight Control System (AFCS), autopilot is an avionics system that automatically controls an airplane’s flight path. Pilots can set targets — altitude, heading, speed, etc. — and the autopilot will respond by making the necessary adjustments to achieve and maintain these settings. Many autopilots can even follow navigation routes or climb and descend automatically.
Autopilot works via servos. Also known as servomechanisms, servos are actuators. They move various aircraft components, such as ailerons and elevators, by converting computer signals into mechanical action.
What Is Flight Director?
Flight director is an avionics system that provides guidance to the pilot. It works in conjunction with the airplane’s primary flight display (PFD). Flight director calculates the necessary pitch and bank angles for a given flight path. It then displays the appropriate commands on the PFD.
Flight director commands typically consist of two horizontal lines or bars. Pilots reference these lines to determine if the airplane is flying at the correct altitude. When the lines are aligned with the aircraft symbol, the airplane is at the correct altitude.
Differences Between Autopilot and Flight Director
While they are both commonly found in modern airplanes, autopilot and flight director aren’t the same. Flight director is a much newer avionics system. It was pioneered in the 1950s, after which it was gradually rolled out in commercial airliners. Autopilot, on the other hand, has been around since 1912.
Autopilot and flight director are used for different purposes. Autopilot mechanically controls the airplane’s flight surfaces. Using servos, it takes computer signals and converts them into mechanical action. Flight director does not control any flight surfaces. Instead, it provides visual guidance to the pilot. The pilot can look at the PFD to leverage the flight director’s assistance.
Autopilot reduces the pilot’s workload. When activated, pilots won’t have to spend as much time or energy adjusting the airplane’s ailerons, elevators or other flight surfaces. Flight director, in comparison, simply helps the pilot by providing key data. It essentially allows pilots to fly manually with precise guidance displayed on the PFD.