Once LOC is captured GPS/FMS plays no part in ILS approach whatsoever. So the examiner is not wrong. If you see PRO-ABN-34 P 13/30 NAV FM/GPS POS DISAGREE it says the following:
If the ECAM alert is displayed during ILS/LOC approach (LOC green):
Continue the approach
Off course if you went around you won't be faulted. You can assess the situation and make another approach. One Examiner telling a few pilots is not much of help. It should be incorporated in the SOP.
Last edited by vilas; 22nd Jan 2018 at 03:04.