Definition
A qualified flight crewmember, separate from the pilots, responsible for monitoring and managing the aircraft's mechanical, electrical, hydraulic, fuel, and pressurization systems during flight. On aircraft certified to require one, the Flight Engineer (also titled Second Officer at some operators) sits at a dedicated systems panel behind or beside the pilots and handles system configuration, troubleshooting, and performance calculations so the pilots can focus on flying and navigating.
Plain English
A third crewmember on certain older or larger aircraft whose job is to run the airplane's systems while the two pilots fly it.
Context Anchor
Seen in multi-crew cockpit procedures, crew duty descriptions, and communication examples where tasks may be assigned to the Flight Engineer or Second Officer.
Derivation
"Flight Engineer" reflects the role's origin: an engineer aboard the flight to manage the aircraft's machinery, much like a ship's engineer manages a vessel's engine room. "Second Officer" follows maritime crew ranking, where the captain is first, the first officer is second-in-command, and the second officer holds the next rank — adapted into aviation use.
Why Pilots Care
On aircraft that require a flight engineer, this role prevents system failures and supports safe operation when pilot workload is high.
Intuition Check
Do not assume a Flight Engineer is the person who designed the aircraft. Here, it means a flight crew member who helps operate and monitor the aircraft’s systems during the flight.
Example Sentence 1
On the Boeing 727, the captain called for the after-takeoff checklist, and the flight engineer reconfigured the pressurization and electrical systems from the panel behind the first officer.
Example Sentence 2
During the approach briefing, the captain asked the FE/SO to confirm hydraulic system status.