Flight mechanic

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 rotary wing helicopters. A similar crew position exists on some spacecraft. 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 (DC-6, DC-7, Constellation, Boeing 307 and 377) and early three- and four-engine jets (Boeing 707, 727, early 747, DC-10) required flight engineers. Later three- and four-engine jets (MD-11, B-747-400 and later) were designed with sufficient automation to eliminate the position.

Not all large aircraft were designed and built with a flight engineer's position, and in many, if not 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.

Historically, as airplanes became ever larger requiring more engines and complex systems to operate, the workload on two pilots became excessive during certain critical parts of the flight regimes, particularly takeoffs and landings. Piston engines on an airplane required a great deal of attention throughout the flight with their multitude of gauges and indicators. Inattention or a missed indication could result in engine or propeller failure, and quite possibly cause the loss of the aircraft if prompt corrective action was not taken.

In order to dedicate a person to monitoring the 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.

...
Wikipedia