Well, thanks for the reply. Actually, I am having a A320 transition training, and everytime I turn the ADIRS off on the simulated device, then "GPS PRIMARY LOST" will appear in the bottom of the ND , which give me the impression that GPS could not be used when the ADIRS are off.
Does this phenomenon comply with the real flight?
One thing else is that if all IRS go off during flight, can GPS still be serviceable for locating position?
