To my understanding, most aircraft use a combination of INS and GPS for both redundancy and spoofing resilience.
This actually makes spoofing attacks very difficult, since you'd need to target each receiver individually and in a very precise way (e.g. a reasonably filtered system would reject a GPS signal indicating that the plane just by a couple of kilometers and changed direction by 90 degrees without any measurable acceleration).
This actually makes spoofing attacks very difficult, since you'd need to target each receiver individually and in a very precise way (e.g. a reasonably filtered system would reject a GPS signal indicating that the plane just by a couple of kilometers and changed direction by 90 degrees without any measurable acceleration).