When you use spectator mode to follow helicopters they continue to gain height until they reach their ceiling, they also fail to continue to follow their waypoints until you stop spectating them ... after which the AI returns to following its waypoint correctly.
Using ArmA III version 1.68.141205.
In the eden editor place a player unit on a map, place any helicopter with crew in the air with some waypoints, start the map and then spectate the helicopter, you will see the helicopter continue to gain height and not follow its waypoints properly.
Also when spectating a tank, the commander continues to issue waypoint orders but the tank does not always follow them, especially after using first person view on the commander in the tank, this maybe true for other vehicles with a commander, (not tested).