I added a simple mission/PBO file:
1) Board the chopper and hover a couple meters off the ground. (side=west)
2) Radio #1 (0-0-1) which will spawn some enemy troops. (side=east).
3) Some troops will aim and track the chopper, but none will fire.
4) Drop and touch the ground. They now open fire and kill you.
5) If you can take off before you die, they will again stop firing.
I ran these tests with no mods. I also tried this with guerrilla troops facing east troops with former set to east-hostile with the same effect. The combatMode and Behaviour are left at default settings.