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.
In earlier days, most larger aircraft were designed and built with a flight engineer's position. For U.S. civilian aircraft that require a flight engineer as part of the crew, the FE must possess an FAA Flight Engineer Certificate with reciprocating, turboprop, or turbojet ratings appropriate to the aircraft. Whereas the four-engine Douglas DC-4 did not require an FE, the FAA type certificates of subsequent four-engine reciprocating engine airplanes (Boeing 307 and 377, DC-6, DC-7, Constellation) and early three- and four-engine jets (Boeing 707, 727, early 747s, DC-8, DC-10, L-1011) required flight engineers. Smaller twinjets (DC-9, 737) were never complex enough to require a flight engineer, while later large two, three, and four-engine jets (Airbus A300, MD-11, 747-400, and later) were designed with sufficient automation to eliminate the position.
In order to dedicate a person to monitor an aircraft's engines and its other critical flight systems, the position of "flight engineer" (FE) was created. The FE did not actually fly the airplane; instead, the FE's position had a specialized control panel allowing for the monitoring and control of various aircraft systems. The FE is therefore an integrated member of the flight deck crew who works in close coordination with the two pilots during all phases of flight.
Traditionally, the FE station has been usually placed on the main flight deck just aft of the pilot and copilot, and close to the navigator.