How do I load a flight plan into an airliner FMC?

To load a flight plan into an airliner FMC, initialise the aircraft position, enter or import the origin, destination and route, add the departure and arrival procedures, remove only unwanted route discontinuities, then activate and execute the route. Check every leg and complete performance data before engaging LNAV or managed navigation.

In real-world aviation and airliner flight simulators, “FMC” is often used loosely for the whole flight-management interface. Boeing crews normally work through a CDU connected to the FMC, while Airbus aircraft use an MCDU to control the FMGS. The page names and confirmation keys differ, but the underlying process is similar.

Three ways to put a route into the FMC

The best loading method depends on what the aircraft supports and how much of the route you want to verify manually.

A route shown on the simulator’s planning map is not necessarily inside the aircraft FMC. If using Microsoft Flight Simulator, first confirm how the built-in planner transfers routes to the aircraft; sophisticated airliners may use their own import system instead.

Real airline crews use operator-approved dispatch routes, uplinks and verification procedures. Simulator file import is a convenience and should not be treated as a substitute for checking the route.

How do I enter or import the route correctly?

1. Power and initialise the navigation system. Complete the aircraft identification and position-initialisation pages. Some models allow route entry while the inertial reference system aligns, but a valid position is still required before navigation.
2. Choose the route source. Use the aircraft’s company-route or route-request function if it supports your plan format. Otherwise, enter the route manually rather than forcing an incompatible file.
3. Enter the origin and destination. Use the four-letter ICAO airport identifiers and confirm that the displayed airports are the intended ones. Add the flight number or alternate only where the aircraft requires it.
4. Load the en-route section. Enter airways in the VIA field and their exit fixes in the TO field on Boeing-style systems. Airbus entry is usually performed from the flight-plan page using lateral revisions. Direct fixes can be entered individually.
5. Select the departure. Choose the runway, SID and transition that match the expected clearance. Do not add a SID twice if the imported route already contains its fixes.
6. Select the arrival and approach. Add the STAR, transition, approach and landing runway when known. These may be left until later if weather or ATC has not settled the arrival.
7. Review discontinuities. Close a discontinuity only when the next leg should follow directly. A discontinuity associated with radar vectors or a manual leg may be intentional; deleting it blindly can create an unsafe shortcut.
8. Activate and commit the route. Boeing-style FMCs normally require route activation followed by EXEC. Airbus systems normally show a temporary flight plan that must be inserted rather than erased.
9. Check every leg. Step through the LEGS or F-PLN pages while watching the navigation display. Look for route loops, duplicate fixes, unexpected headings, incorrect waypoint selections and implausible altitude constraints.
10. Complete performance setup. Enter the required weights, reserves, cruise altitude, cost index and take-off data. Importing the lateral route rarely completes all the information needed for VNAV or managed climb.

What changes between Boeing and Airbus FMC programming?

Boeing-style systems generally use the RTE, DEP/ARR and LEGS pages, followed by ACTIVATE and EXEC. For a model-specific example, our 737 route-programming sequence shows where each part of the plan is entered and checked.

Airbus aircraft usually build the route through the INIT and F-PLN pages, with departures, arrivals and airway entries opened through lateral revisions. Proposed changes remain temporary until INSERT is selected. The A320 cockpit flow and FMGS setup explains where this work belongs in the wider pre-flight sequence.

Exact labels vary among aircraft generations and simulator add-ons. Follow the simulated aircraft’s documentation when its interface differs from these common conventions.

Why will the FMC not load my flight plan?

• NOT IN DATABASE: the waypoint may be misspelt, absent from the aircraft’s navigation database or drawn from a different data cycle. If several waypoints share a name, select the one that fits the airway and geographical position.
• INVALID ENTRY or format errors: the scratchpad entry is in the wrong field or uses syntax that the FMC does not accept. Check whether the page expects an airway, waypoint, route identifier or file name.
• Only the origin and destination appear: the aircraft may not support that import format, or the planner may have exported an incomplete route. Enter the en-route fixes manually and add procedures in the cockpit.
• The SID or STAR creates a loop: an imported procedure may overlap with one selected manually. Remove the duplicated procedure or transition, then inspect the connecting legs again.
• The route remains modified or temporary: it has not been executed or inserted. Commit the change before expecting the navigation display or autopilot to follow it.
• The route is active but LNAV will not engage: check for an invalid active leg, excessive distance from the route or an unsuitable intercept angle. Our LNAV and VNAV fault checks cover the next diagnostic steps.

How do I know the FMC route is ready to fly?

A route is ready only when it is active, geographically sensible and consistent with the clearance or intended simulator flight.

• The origin, destination, runway and first waypoint are correct.
• No unexamined route discontinuities, duplicate fixes or loops remain.
• The first active leg gives the aircraft a sensible path to intercept.
• The SID, STAR, transitions and approach connect in the expected order.
• Altitude and speed constraints are plausible for the selected procedures.
• No pending MOD or temporary flight plan remains.
• The performance pages contain the data required by the aircraft before VNAV or managed navigation is used.

Do not judge the plan solely by the presence of a magenta line. The decisive check is stepping through each leg on the FMC while comparing it with the navigation display and the route you intended to fly.