Pilot - Co-pilot

The presence of two pilots in a crew is one of the key points to airline safety. Technically speaking, any modern airliner could be flown by a 6 years old, given all the automatics work good.

A common joke says that three things are needed to fly a plane: a computer, a pilot and a dog. The computer to fly the plane, the pilot to feed the dog, and the dog to bite the pilot if he tries to touch the controls.

The crew operates according to the airline standards, and includes a captain and a co-pilot. This distinction only defines who is holding the final autority. There is a second distinction which defines the operational roles of each: pilot flying and pilot non-flying. This is normally defned before each leg, and they normally change for each leg.

The principle is simple: the pilot flying manages to keep the plane in a correct attitude, and to fly it, or manage the auto-pilot. The pilot non flying manages navigation, communication, and monitors the pilot flying.

This split of tasks is something like tactics (pilot flying) and strategy (pilot non flying). One is managing short term, while the other is working on a longer term. This has proven to be a very efficient way to have a crew of two reaching very good safety.

A crash years ago involved a crew having problems with the flight computer, who did not behaved as expected. The normal way to work it out would have been to have the pilot flying to manually fly the aircraft while the pilot non flying would manage the computer problem.

In that case, both pilot and copilot started working on the computer, so no one was flying the plane. This was shortly after take-off, and the plane crashed after flying a barrel.

One other critical issue with the non flying pilot monitoring the flying pilot is that they must have a quite similar experience. In an unbalanced crew, there is a risk that the flying pilot would not listen to remarks from the non flying pilot.

So there are crew of two not because the task can not be managed by one, but to introduce redundancy, and because co-operation, when well defined, makes 1 + 1 greater than 2.