If anything media has taught us since the 80s, is that it's not giant monster nor other military weapons/vehicles are the biggest threats to helicopters. It turns out the #1 threat to helicopters, or other specific aircrafts, are ninjas.....damn....You read that right. I noticed this trend started with Shinobi (which it does a lot when you stop and think about it), and Ninja Gaiden picked up on this in the 3D titles. Especially in 3:Razor's Edge. Even Yaiba kills a few early on in Ninja Gaiden Z. Then you have Metal Gear Rising and Ninja Blade (the helicopter pilot mutated into a monster) as well. At this point: Ninjas are the natural predators and helicopters are the natural prey.