The core functionality of the Flight Management System (FMS) is the creation of a flight plan and of the four-dimensional aircraft trajectory. The Flight Management System helps to reduce the flight crew’s workload by providing the following major functions:

• Aid for fuel management - improve fuel efficiency and performance optimization:

The FMS has the ability to provide correct fuel computations even in engine-out configuration. This greatly reduces the flight crew’s workload, especially under such stressful conditions.

•  Aid with navigation - lateral and vertical flight plan management:

The FMS calculates the aircraft trajectory so that it respects any inserted constraints (altitude, speed, distance, etc.

• Aircraft position computation:

The FMS computed position along the flight plan is derived from the data provided by the IRS, DME, VOR, and GPS. A monitoring section is provided in the MCDU where you can actually check the accuracy and integrity of the GPS signal and select the desired position computation method.

• Autotuning – automatic tuning of the radio navigation frequencies.

The autotuning function automatically tunes the radio navigation facilities based on the available signals in terms of geometry and strength. The workload is greatly reduced because the flight crew only need to cross-check with their charts that the correct frequencies are automatically inserted.