Plain English Meaning

A central flight computer that handles navigation and flight planning for the pilot. The pilot enters the route and key information, and the system tracks position, calculates the path, and feeds guidance to the autopilot and cockpit displays.

Full Definition

An integrated onboard computer system that automates a wide range of in-flight tasks, including navigation, performance calculations, and flight planning. The FMS combines inputs from sensors such as GPS, inertial reference units, and air data computers to determine position, calculate , and provide guidance to the autopilot and flight displays.