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Flight Management System
What is the Flight Management System (FMS) and Why it is required in the aeroplane?

The FMS is the navigation system like the navigation that everyone uses in their car. The FMS guides the pilot to navigate from source airport to destination airport.

The FMS also gives the optimized route to the pilot which would save the time and increase the fuel efficiency of the aircraft.


What could be the location of FMS in the aircraft?



Position of Flight Management system in the Aircraft


The FMS is in the cockpit of the aircraft. It is located between Captain and First Officer(FO) in the cockpit. The FMS has three sets of units (L CDU, R CDU and C CDU) used by the captain and first officer(FO).

The left control display unit (L CDU) used by captain and the right control display unit (R CDU) used by the FO. The Center CDU (C CDU) is used for satellite communication and maintenance operation of the aircraft



Function of FMS and its need in the aircraft:


The Pilots use FMS for flight guidance and the control (vertical & lateral) of the aircraft. The flight envelope of the aircraft is also monitored. The optimum speed and safety margins with respect to SM (safety margins) are maintained with the help of FMS.

The aircraft’s engine control also is done using FMS by controlling the cruise speed.

The modern generation aircraft, like Airbus A350 XWB and 777X, can turn on the autopilot after take-off to a certain altitude.



Major parts of FMS:



Typical Flight Management system in the Aircraft


A typical FMS consists of 2 Flight Management Computers and 2 CDUs. The two FMC and CDU are use by Captain and first officer respectively.

The CDU acts as interface between pilot and the FMCs. The Airbus A320 aircraft first used this system. It combines the data from various sources for navigation and performance.

The NAV and GPS data also calculated by the FMCs to find the aircraft position with respect to the destination.



Flight Management Computer



Control Display Unit (CDU)



EFIS (Electronic Flight Instrument System)




How does FMS work in the aeroplane?




Working of Flight Management Computer 



The Flight Management Computer is fetches information from GPS, NAV (Inertial Navigation systems), Flight Control systems, Air data computer, Engine and Thrust management system, Aircraft specific performance like aircraft weights, Route, and Pilot inputs.



 Flight Control System of Boeing KC-46(Also used in variant of Northrop Grumman E-10) 



Autopilot panel used in Boeing KC-46 aircraft



Thrust Management System of Boeing KC-46 aircraft


FMS receives from all the systems and provide the optimum flight plan to the pilot which would enable the pilot to engage autopilot and monitor the critical systems of the aircraft.


Importance of FMS in modern aircraft:


  • Makes easy for the pilot to monitor and maintain the health of aircraft
  • Flight Computer data are more accurate.
  • Weather and air traffic management makes easier when FMS is used.
  • Seamless low visibility guidance.