A flight engineer is a flight crew member who is responsible for monitoring aircraft systems in flight and for checking the aircraft before and after each flight. In civil operations and some military aircraft the flight engineer sits behind the pilot and co-pilot in the cockpit, facing a side panel of gauges and indicators. In other military aircraft, flight engineers sit between the pilots (P-3 Orion and C-130H). The flight engineer is the aircraft systems expert onboard and responsible for toubleshooting and suggesting solutions to in-flight emergencies, as well as (in civil aviation) computing take-off and landing data.

Modern airliners do not require flight engineers, although they are still found on older models such as the Boeing 747-100 and -300, Boeing 727, Lockheed L-1011, and McDonnell Douglas DC-10. Newer aircraft monitor systems automatically, by computer, and report malfunctions directly to the pilot-in-command and the copilot.