Closing an F-PLN Discontinuity
beginnerDecode the "F-PLN DISCONTINUITY" line on the A320 MCDU — what it is, why the FMS inserts it between your departure and destination, and exactly how to close the gap so your route is continuous.
Start this scenario
Open the SimTuts A320 MCDU trainer and select “Closing an F-PLN Discontinuity” from the scenarios list to walk through it step-by-step on the simulated keypad.
Open trainer →Step-by-step: Closing an F-PLN Discontinuity
- Enter a route to work with. Type EGLL/LFPG into the scratchpad and press 1R.
EGLL is London Heathrow, LFPG is Paris Charles de Gaulle. As soon as you enter FROM/TO, the FMS has two endpoints but no path between them — so it inserts a discontinuity to mark the gap it cannot connect on its own.
- Press the F-PLN key to open the flight plan and see the discontinuity.
A discontinuity (shown as ---F-PLN DISCONTINUITY---) is a deliberate break in the route. The FMS will NOT fly across it — in the real aircraft, reaching a discontinuity drops the autopilot out of managed NAV and it flies straight ahead. That is why you must close every discontinuity before departure. It is not an error; it is the FMS telling you "I don't know how to join these two points — you decide."
- Close the gap. Type DVR into the scratchpad, then press 2L — the line select key next to the discontinuity line. The FMS replaces the discontinuity with DVR.
To close a discontinuity you put a waypoint in the scratchpad and click the discontinuity's line key. The FMS drops the gap and slots your waypoint in, joining the route. Note the difference from clicking a normal waypoint: clicking a waypoint line with an EMPTY scratchpad opens the LAT REV menu instead — the discontinuity only closes when a waypoint name is waiting in the scratchpad.
- Now extend the route. Type KONAN into the scratchpad and press 3L (the line next to LFPG) to insert it before LFPG. Your route is now continuous: EGLL → DVR → KONAN → LFPG.
Typing a waypoint and clicking a normal waypoint's line key inserts the new waypoint BEFORE the one you clicked — the clicked waypoint slides down. That is the standard Airbus way to build out a route by hand. There is no discontinuity left, so the FMS can now fly the whole path in managed NAV.