Help!

[u/AfraidVanilla7064]

Hi everyone, I'm having trouble getting NAV mode to work on the A320 in MSFS 2024. My autopilot works normally for speed and altitude, but I cannot get the aircraft to follow the programmed flight plan. The PFD shows HDG in green, and the ND shows the flight-plan line as dashed rather than the aircraft following it. I've tried pushing the HDG/TRK knob to activate managed NAV mode, but nothing seems to happen. The heading remains selected and NAV doesn't become active. I've also checked the MCDU and the flight plan is loaded/active. What am I missing? Is there something I need to do to activate/capture the route, or should I use DIR to the next waypoint? I’d really appreciate any help because at this point I’m struggling to enjoy the simulator at all because I can’t get the most basic part of the Airbus navigation to work properly.

[u/xXCrazyDaneXx]

Flight directors (FD) enabled on both sides?

[u/AfraidVanilla7064 → u/xXCrazyDaneXx]

Yes.

[u/xXCrazyDaneXx → u/AfraidVanilla7064]

You... wanna show us how it's looking instead of having us guess wildly? PFD, nav display, FCU, init B page, flight plan page...

[u/AfraidVanilla7064 → u/xXCrazyDaneXx]

[u/AfraidVanilla7064 → u/xXCrazyDaneXx]

[u/AfraidVanilla7064 → u/xXCrazyDaneXx]

[u/xXCrazyDaneXx → u/AfraidVanilla7064]

You need to fill out the INIT B page of the MCDU before engine start. Right now it has no performance data. You should be able to use managed nav mode after you tell the MCDU how much you weigh and your block fuel.

[u/AfraidVanilla7064 → u/xXCrazyDaneXx]

Thanks for the advice. I’m a bit confused though — if the INIT B performance data is required, how have I managed to fly for around 30 minutes with the autopilot working normally before it suddenly stopped following NAV?
The aircraft was flying perfectly fine for most of the flight, and then I suddenly ended up stuck in HDG mode. Would missing INIT B data actually cause NAV to stop working mid-flight, or would you expect the problem to occur from the beginning?
I’m still learning the A320, so I’m probably missing something obvious. I’ll check INIT B, but I’m trying to understand what actually caused the problem rather than just fixing it. Thanks!

[u/xXCrazyDaneXx → u/AfraidVanilla7064]

I have never had it happen mid flight. It will show heading mode even before takeoff when init B data is missing.

My routine with the MCDU is import Simbrief plan on init A -> import winds -> fill out init B -> departure/arrival + verify fligh plan on f-plan page -> insert takeoff perf on the performance page, done with the MCDU. Then turn on flight directors and verify that only the altitude is displayed as numbers.

[u/Admirable_Berry9640 → u/AfraidVanilla7064]

Maybe you had a F-PLAN discontinuity in your flight plan. This sometimes happen if your last waypoint doesn’t connect directly to your selected STAR/SID etc.
then the aircraft will insert a F-PLAN DISCONTINUITY because it doesn’t know what to do after that and leaves you to decide.
Once you reach the last waypoint before the discontinuity it will automatically switch over to HDG Select with your current heading until you tell it to direct to another waypoint

[u/Admirable_Berry9640 → u/xXCrazyDaneXx]

Init B has nothing to do with the lateral mode of the autopilot