This may be a bug, I have found a bug similar to this.
I was just goofing off and was trying to make a health script that would give AI extra health, but if the soldier died even for a second the other AI soldiers just say "Oh, well he WAS dead might as well just leave him alone."
Even if he starts shooting them they just look at the sky!
This may be a bug, and if possilble I would try switching chopper with setpos really fast.