For me this seems like a bug. This makes the Helicopter pretty much unusuable for any Mission. Why do I think its a bug? Cause you are immune to Missles. The only thing that can Kill you are Bullets (And even then you have to be lucky to not get the Stuck in the air bug). That Automatic AA mechanic makes no sense in my opionion. It doesnt matter how High or low you fly, or if you set up the IR jammer and all, there is no need. Just get into the Heli and take off, you will be safe from missles forever.