How Does An Autopilot Work On Airplanes?

An autopilot is an airplane feature that controls or directs the aircraft without any pilot input. Autopilots have been installed in most civilian and military airplanes since the 1940s. Autopilots are used for takeoff, landing and cruising flight by using automation to provide control of aircraft speed, heading, pitch and roll. In modern aviation systems the autopilot is typically the primary method of controlling a commercial airliner.

Airplanes are complicated machines full of sophisticated technology that takes years to learn how it all works. That’s why autopilots exist — they help reduce stress on pilots. Here’s how an autopilot works and why it’s so important to modern air travel.

The autopilot is a control mechanism that takes over some of the workload from a pilot. The autopilot is typically installed in the cockpit, but on larger aircraft it may be located elsewhere on the plane. The autopilot’s sensors help it track certain parameters, like altitude and speed as well as what direction the plane is going in. It also controls other simpler elements of flight like pitch, roll and heading (where the nose of the plane is facing). Typically there are several autopilots on each of the airplane’s wings and fuselage, but sometimes only one is installed in the tail section of the plane. Airplanes have so many parts, however, that some planes require multiple autopilots to prevent pilot inattention from disrupting flight — for example, when one pilot takes control of two out of three autopilots to check things out.

The autopilot is what pilots call a “slave” autopilot. It doesn’t take over the flying of an airplane itself. Instead, it acts as a “slave” to the pilot. That means the airplane’s autopilot helps make decisions on where to go and how to get there, in addition to introducing less-stressful elements into the flying process. Some of these include:

Direction . The autopilot controls heading by calculating where the nose of the plane should be pointed, sometimes involving inputs from other parts of the plane’s flight system, like engine torque and airspeed.

The autopilot controls heading by calculating where the nose of the plane should be pointed, sometimes involving inputs from other parts of the plane’s flight system, like engine torque and airspeed. Speed . As an aircraft climbs, it increases airspeed — that is, until it reaches cruising altitude. At that point a pilot adjusts throttle to stabilize speed. The autopilot then controls a constant airspeed (drift) and methodically brings altitude down as the airplane heads toward its destination airport.

As an aircraft climbs, it increases airspeed — that is, until it reaches cruising altitude. At that point a pilot adjusts throttle to stabilize speed. The autopilot then controls a constant airspeed (drift) and methodically brings altitude down as the airplane heads toward its destination airport. Control. The autopilot also controls pitch, roll and thrust — allowing most of the plane’s other systems to be controlled manually by the pilot. This helps reduce pilot stress and fatigue, making their job easier than if they had to control each system independently. You can read more about how autopilots help reduce pilot stress in our article on how pilots fly.

Most modern airliners have two or three autopilots and most pilots train with a minimum of four because they are expected to handle an airplane’s systems — including the autopilot — even while flying manually. Pilots can also adjust the number of autopilots they use depending on the complexity of their airplane. Pilots who work with bigger jets must learn to use more than one or two autopilots at a time, and those who fly smaller airplanes typically don’t even need one.

Here are some of the ways a pilot can adjust how many autopilots they use:

Autopilot Engagement . A pilot can engage one or more of the autopilots at any time, allowing them to have a lot of control over the aircraft if they need it.

A pilot can engage one or more of the autopilots at any time, allowing them to have a lot of control over the aircraft if they need it. Autopilot Disengagement. In most cases, pilots fall back on their autopilot when there’s an emergency situation with another system on their aircraft or during takeoff and landing due to spatial disorientation.