What it is: In airliner and some business jet simulations, the FMC is the interface used to enter the flight plan, departure and arrival procedures, cruise altitude, speeds, weights and fuel figures. It works with the autopilot, navigation radios and aircraft sensors to calculate where the aircraft should go and how it should fly the profile.
In practice: During a simulated flight, you will usually use the FMC before departure to load the route from the world map or a planner, select the SID, STAR and approach, then check the legs page for discontinuities or incorrect turns. Once airborne, the FMC drives LNAV and VNAV if the aircraft supports them, helping the jet follow programmed tracks, altitude restrictions and speed targets. Simmers also use it to make direct-to changes, alter cruise levels, enter approach data and monitor top of climb or top of descent points.
Key considerations:
- Different aircraft simulate the FMC to very different standards, so available pages and functions can vary a lot.
- Imported routes often need manual checking, especially procedure transitions, altitude constraints and route discontinuities.
- An FMC can provide guidance, but the autopilot must be set up correctly for the aircraft to follow it.
