Create a rescue helicopter (Mi-8) and give it waypoints, make sure one is a decent way from the pickup point and another is the pickup point. On a waypoint some distance away go advanced waypoint actions, perform task, orbit. Put him in a slow circle.
Then at the waypoint next to the pickup go advanced waypoint actions, perform task, land, stop condition, Duration 10 seconds. Move the triangle that appears on the map to the desired landing point.
Next you need a triggered action, go to the triggered actions menu for the pickup helicopter, add, perform command, switch waypoint, and then select the waypoint after the orbit waypoint.
Now create a trigger, once-->Group dead "AA group." (make as many of these as you need-->AI task "Switch waypoint."
What will happen is the rescue helicopter will reach a waypoint some distance from the target and orbit. When you have killed the AA groups he will go to the next waypoint and follow those until he reaches the land waypoint. There he will land, wait ten seconds and leave.
I'll make an example mission. Here you go, a after two minutes the vulcan guarding the wreckage will explode on it's own and the Mi-8 should land.
Example.miz