Simple controls for a helicopter

I have a helicopter that moves using the wasd keys. Horizontal to move left and right, vertical to move forward and backward. I have the game camera attached to a child object of the helicopter.

Now how would I have the copter's Y rotation equal to the camera's Y rotation when a vertical key is pressed?

Also having the Y rotation perpendicular to camera's Y rotation when a horizontal key is pressed?

EDIT: Sorry I forgot to mention I would prefer using C#.

The second questions is really hard for me to explain, It would probably be easier with a picture I suppose but I'm not even sure how I would do that. Hmm.

I think you're thinking to hard. You might just want to try putting the camera-control `Smooth Follow` on your camera, and setting the transform variable in the inspector to be your helicopter. Anyway, here's your script:

var cam : Transform;

function Update () {
    if (Input.GetButtonDown ("Fire1")) {
        transform.rotation.y = cam.rotation.y;
    }
}

Put that on your helicopter, and you should be set to go. Not sure what you mean by

having the Y rotation perpendicular to camera's Y rotation when a horizontal key is pressed

though. If you're more specific on that, I'll see if I can help you some more.

You can take screenshot by pressing Prt Scr button and starting paint and pressing ctrl+v. If you need more material for studying vehicles like helis check this page InfiniteUnity3d