Q How does autopilot work, and what is its contribution to science?
— Maggie Tate, Middleton, Wis.
A Chris Johnson, director of the University of Wisconsin-Madison’s Flight Simulation Research Laboratory:
An autopilot is a flight control system that allows a pilot to fly an airplane without continuous hands-on control. This allows the pilot to focus on higher-order tasks such as navigating, communicating with air traffic control, planning for weather contingencies and rerouting the airplane in the event of an emergency.
Autoflight systems work by sending signals to a flight control system. The pilot inputs information like heading or altitude. This allows the plane to hold a specific heading, like 360 for north or 180 for south, or a specific altitude: 3,000, 8,000 or 37,000 feet. More sophisticated autoflight systems can maintain a navigational course. Pilots program a GPS to maintain a specific course, and an autoflight system will take the desired turns to get from point A to point B.
Autopilots actually fly straighter than humans because they can maintain a steady trajectory from one point to another while a pilot has to constantly control the aircraft. This allows the plane to burn less fuel and save the airline money and time.
So you can think of an autopilot as an extra crew member. Pilots do three things when they fly the airplane: They aviate, that is, they provide actual hands-on, stick-and-rudder control. They navigate, or plan a route. And they communicate with air traffic control, monitor on-board systems or mechanical components of the aircraft and plan for weather contingencies.
Autopilot largely frees the pilot from actually aviating, the hands-on control.