You can't put beacons on vehicles. Well, at least not empty ones. I tried to jump on top of an empty APC in a practice mode game, and when I set the beacon, it just froze in one place. I moved the APC, and the beacon stayed where it was...yes, it floated in the air. An eerie effect if any.

So, my guess is that if you tried this with the plane, it would just freeze in one place. I haven't tried to place a beacon on a vehicle with people in it though, maybe things would happen diffrently...