There is a very important rule for commercial aircrafts (these include all aircrafts that transport people or goods): They have to be flown by at least two pilots – a captain and a co-pilot. That is because operating an aircraft is not easy: There are many displays, buttons and control units in the cockpit. In addition, there are, of course, other planes in the air and depending on the weather the pilots have to concentrate even harder. There are various devices to help them fly the aircraft, such as the autopilot.
This means the autopilot is not a human, but a machine, or a computer system to be more precise. The term "auto pilot" comprises of two words: automat and pilot. You already know what a pilot is. Automats are machines that can carry out tasks independently – i.e. automatically.
On the plane, it is the task of the autopilot to support the pilot. However, it cannot work completely on its own. The pilots first have to programme it. Then, for example, it can help keep the altitude, or balance out the plane when it is windy or when the plane flies through an air pocket.
The autopilot does not control the plane itself, but actually sends certain control commands to other computers. These then adjust the rudders and elevators of the plane, for example. Furthermore, the plane flies steadily when computer controlled and thus consumes less fuel – this saves money and protects the environment.
Thus, the various systems are interconnected and together they help the pilots reach their destination safely. Some autopilots can also assist with the landing process. Nevertheless, it always requires a human to check and adjust the instruments and also the autopilot. By the way: autopilots are not exclusively used in the field of aviation. They are also used among other things for space travel or on ships.