Jump close to it and use air kick followed by grab. You can also use whipfist to hijack it after you've purchased the "long shot grab" ability; just equip whipfist and press grab when you're close enough to the helicopter.
when you get the mechanic, you'll get a grappling hook. When you want to hijack a helicopter, point the cross hair at it and if your close enough, it will come up with an option to grapple it. Click...
When your character awakens in the prototype EMP hardened helicopter, look to your left and you will see a red button on the left side of the door. press it and you should be ejected from the...
The AH-1 Cobra was the first attack helicopter that saw general combat service in 1965/66 (not a proto-type experiment).The AH-56 Cheyenne gunship made it's first experimental flight in 1967.