While playing around with that feature, I realised, that the aiming from the bench of the choppers or seats from the other vehicles is too limited.
I know, that you are strapped to the chopper but that doesn't mean, that you can't aim to the sides, straight up and down. It should be possible to shoot straight up-, down-, and sidewards in the WY-55 Hellcat.
The same for the Hummingbird. The soldier is not able to shoot straight downwards. In real life you are able to lean your upper body a little bit so you won't shoot in your own foot.
If you sit in the Assault Boat on the left side, you only can aim your weapon to the front, but not the right side (same from the right side). If there is an enemy near the boat (1m) in the water, you can't shoot him because of limitation.
Please think about that limitation and give us a little bit more possibilities. Every passenger should pay attention to not shoot the teammates in the vehicle or himself.