+1
Probably easier to implement than trucking as well as there's only 4 airports (5 if you include the runway at Area 51?)
Some ideas:
Flying aircraft to abandoned airport at Verdant Meadows (Aircraft Graveyard). This aircraft will be damaged with very low HP and need to be flown carefully.
Passenger flights between LS, SF, LV (Shamal, Andromeda, AT-400, Beagle, Nevada)
Cargo flights between LS, SF, LV (Andromeda, AT-400, Nevada, Beagle)
Military cargo flights to Area 51 (Andromeda, AT-400, Nevada, Beagle)
Skydiving passengers - Take off at any airport, fly into a marker at high altitude. Starts cutscene of NPCs skydiving from plane. Return to base. (Dodo, Nevada)