Closing an F-PLN Discontinuity

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📍 Route: EGLL → DVR → KONAN → LFPG⏱ ~4 minutes📊 4 steps🎓 Flight Plans & Routing

The F-PLN DISCONTINUITY line is not an error message. It is the FMGS telling you it does not know how you intend to join two pieces of route.

What this scenario covers

A discontinuity appears wherever the flight plan has a gap the box cannot fill on its own — typically between the end of a departure procedure and the start of the enroute portion, or between an arrival and an approach. Rather than guess a track, the FMGS marks the join and waits.

Closing it is a clear-and-connect operation on the F-PLN page: remove the discontinuity so the waypoint before it links straight to the waypoint after. The result you are looking for is a continuous route with sensible distances either side of the join.

Route map for Closing an F-PLN Discontinuity
The EGLL → LFPG route this scenario programs.

How it applies in flight ops

Discontinuities matter because managed lateral navigation will not fly through one. Left in place, the aircraft flies to the last waypoint before the gap and then keeps its heading — which is fine if you meant to be vectored, and very much not fine if you thought the aircraft was following the plan.

Real crews leave them in deliberately sometimes: a discontinuity after the last SID waypoint is an honest representation of "expect vectors". The skill is knowing which of your discontinuities are intentional.

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Step-by-step: Closing an F-PLN Discontinuity

  1. 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.

  2. 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."

  3. 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.

  4. 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.

What to take away

  • A discontinuity is a gap the FMGS refuses to guess across, not a fault.
  • Managed NAV will not fly through one — the aircraft continues on heading.
  • Close it on F-PLN so the waypoints either side connect directly.
  • Some discontinuities are intentional; know which of yours are.

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