film techniques - Is a helicopter used to shoot such scenes?

The Aerial Shot:

An exciting variation of a crane shot, usually taken from a helicopter. This is often used at the beginning of a film, in order to establish setting and movement. A helicopter is like a particularly flexible sort of crane - it can go anywhere, keep up with anything, move in and out of a scene, and convey real drama and exhilaration — so long as you don't need to get too close to your actors or use location sound with the shots.

The following link will give you a complete detail about camera angles and shots

http://www.mediaknowall.com/camangles.html