What is the function of the Flight Management System (FMS)?

• A. Provides pilot and crew with highly accurate and automatic long-range navigation capability, blending available inputs from long- and short- range sensors.
• B. Controls cabin pressurization system.
• C. Provides weather radar display.
• D. Acts as a manual autopilot override.

Answer: (A)

Automated navigation and flight planning are what the Flight Management System does. It uses a stored route and performance data to build an optimal flight plan, then blends data from long-range sensors (like GPS and the inertial reference system) with other navigation inputs to determine the aircraft’s precise position and the best path to fly. With this fused information, the FMS computes climb/descent profiles, speeds, altitudes, and fuel use, and provides guidance to the aircraft’s navigation and guidance systems in LNAV and VNAV modes, so the aircraft can follow the plan automatically and adjust as conditions change. It reduces pilot workload by keeping the route, timing, and performance optimized throughout the flight. The other functions listed—cabin pressurization control, weather radar display, and manual autopilot override—are handled by separate systems, not the FMS itself.