What is the FMS?

“A computer system that automates a variety of in-flight tasks, reducing the workload of the flight crew” to the point that modern civilian aircraft no longer require flight engineers or navigators. It’s main function is the flight plan.

Jobs it replaced:

• Flight Engineer
  • Was responsible for engine and fuel management, as well as the other systems onboard (E.G. electrical & hydraulic)
  • There was usually an additional seat in the cockpit for the flight engineer, located in front of the “Engineers Station”
• Navigator
  • Plan route and constantly check the aircraft position, ensuring the pilots were flying in the right direction.

Main Functions

• Providing route guidance to the pilot and autopilot system
  • AIRAC data (Aeronautical Information Regulation And Control)
• Constantly check the position of the aircraft (see Navigator), using one of or an average of:
  • Using GPS
  • Cross check multiple VOR or NDB stations
  • Using the onboard IRS (Inertial Reference System)
• Interface with engine management system to optimise aircraft performance
  • Calculate efficient engine performance and fuel usage (weather, weight etc.)
  • Optimal rate of climb and cruise speed for fuel efficiency and engine lifespan.

How is it used?

The pilots  interface with the FMS using the CDU (Control Display Unit)

• The numberpad and keypad
  • Used to enter data into the CDU
• Navigation buttons
  • Takes you to different screens and menus in the FMS
  • Allows to navigate in the GUI
• GUI (Display)
  • Displays information
  • Further broken down (from the bottom, left to right) with corresponding “soft keys” for each section for copying and pasting as well as additional functions:
  • The scratchpad
    • Allows the pilot to see the information they are entering into the display to check for any errors
    • Displays some messages
  • CRZ FL/TEMP
  • TROPO
  • COST INDEX
  • [BLANK]
  • LAT/LONG
    • Updates the aircraft latitude and longitude, starting with the departure airport entered (AIRAC data)
  • FLT NBR
    • Allows for the flight number to be entered
  • [BLANK]
  • ALTN/CO RTE
  • ALTN
  • CO RTE
  • FROM/TO (Departure and arrival airports)
    • Expects 4 digit airport codes, will respond with “BAD FORMAT” if a mistake is made