Follow these steps:
1. First give the chopper a name like, myhelo then give the player a name like player
2. In the condition of the trigger put this
player in thislist;
That will make the trigger activate when the player walks into it.
3. In the OnAct of the trigger put what Wolle posted:
myhelo move getPos player; myhelo setCombatMode "RED"
There you go, and Wolle, you beat me to it:p