Definition
A third flight crew member, in addition to the captain and first officer, who operates and monitors the aircraft's mechanical and electrical systems on flight decks designed for three-pilot operation. The Flight Engineer (FE) title is traditional on older aircraft with a dedicated systems panel; Second Officer (SO) is the equivalent role title used by some operators. The position requires an FAA Flight Engineer certificate.
Plain English
A third crew member on the flight deck whose job is to run the aircraft's systems—engines, fuel, electrical, hydraulics, pressurization—while the two pilots fly the airplane.
Context Anchor
Seen in FAA communications material when identifying who on a flight crew may handle or assist with radio and cockpit communication duties.
Derivation
Flight Engineer comes from the engineering role of monitoring and managing machinery; Second Officer reflects naval/maritime crew rank tradition, where the first officer is second-in-command and the second officer is third. Both titles describe the same flight deck position.
Why Pilots Care
Proper use of this role keeps workload divided so pilots can focus on flying and decision-making, reducing errors in complex operations.
Intuition Check
Do not assume “second officer” means the same thing as “first officer.” In this context, FE/SO refers to a separate crew role used on aircraft that require an additional systems-focused crewmember.
Example Sentence 1
On the Boeing 727, the FE/SO sits sideways at a panel behind the first officer and manages the fuel, electrical, and pressurization systems throughout the flight.
Example Sentence 2
On the older jet, the captain asked the FE/SO to cross-check the hydraulic pressure.