A320 lateral deviation on ND on final approach

[767-300ER]

Flown a few approaches recently on old A320s, (very old editions with the original FMGC). These are non-GPS aircraft.

Flying an ILS, passing the FAF, noticed that the ND shows a course deviation of 99.9L.

Anyone have any ideas on what is happening here? Or how to troubleshoot this? We have managed to get a few photos of this but at this point of the approach, its not the place for trouble shooting.

No other ECAM or MCDU scratch pad messages when this occurs.

Thanks for any suggestions.

[stilton]

Not familiar with the AB ND so its not obvious to me but what you describe sounds a lot like the map shifts we used to experience on our B757's before they installed GPS to provide updating.


Used to happen in areas of minimal or no radio updating and, oddly enough in areas of
massive updating, too much to consider I suppose.

[Capn Bloggs]

ND shows a course deviation of 99.9L.

"Tracking!"

[underfire]

Perhaps I am confused, but a glass cockpit without GPS?

[ACMS]

Yeah amazing isn't it.......how did we navigate before GPS????

I flew glass cockpit 737 and 744 for years before GPS, we didn't get lost either.

I guess you wouldn't know about steam driven classic cockpits then?

[767-300ER]

yes, it is amazing...A320s flying without GPS, WAAS, LAAS, MLS etc.....

[underfire]

I was just wondering why upgrade to glass and not GPS?

[Denti]

Because glass predates the widespread use of GPS? And it doesn't always makes economically sense to upgrade to GPS, especially on airbii retrofitting is very costly indeed.

[Prober]

I am not familiar with the AB display, but it does not seem to be too dissimilar to the 75/76. I presume that one pic is from before the FAF and the other after. Both show 99.9L (99.9L what? Miles? I expect so). Whether its in 'Tracking' or 'Course' would seem to be irrelevant. In pic 1 the ILS shows 267 degs at Victoria BC and in pic 2 298 degs at Edmonton Alberta. This is NOT a map shift - it has to be a software glitch of a fairly large proportion.. Also, there has been a dramatic veering of the wind - maybe there was, but I doubt it. In both cases the applied wind correction would appear to be approximately correct.
prober

[underfire]

Prober..I dont think they are the same approach, but simply 2 examples. (other than CYYJ is 269, not 267)

[767-300ER]

Yes, they are just two examples where I have observed this happening.