A flight engineer (FE), also sometimes called an air engineer, is the member of an aircraft's flight crew who monitors and operates its complex aircraft systems. In the early era of aviation, the position was sometimes referred to as the "air mechanic". Flight engineers can still be found on some larger fixed-wing airplanes and helicopters. A similar crew position exists on some spacecraft. In most modern aircraft, their complex systems are both monitored and adjusted by electronic microprocessors and computers, resulting in the elimination of the flight engineer's position.

Aircrew, also called flight crew, are personnel who operate an aircraft while in flight. The composition of a flight's crew depends on the type of aircraft, plus the flight's duration and purpose.