Originally Posted by
rickair7777
Probably not jamming, at least not targeted at you. GPS jamming targeted at you would render it useless. GPS signals are very weak.
It might have been RF inteference, either authorized or unauthorized. Might also have been jamming targeted at something else nearby, depending on where you were when it happened. In the US they issue NOTAMs before they do that.
What he described sounds exactly like GPS jamming where the FMS starts using other means of discerning aircraft position and ANP rapidly rises.