move backwards towards the cabin after the blast,
look at the stairs above the cabin, platform above the cabin doesnt sank and then slip
behind the iron pole and fire the helicopter with the rocket launcher, 6-7 perfect shots
will kill the helicopter

yah. i got stuck to. But i past it. Well, my brother did...

Yeah i got stuck too, all you gotta do is hide in the cabin and keep firing the bazooka
about 7-10 times at the chooper and eventually it will catch fire and go away!