Shyt...
You know what I mean. They spin their heads and the gun moves where they look, is it string, fancy lights, a helmet proximity system. In the video the man is waggling his head from side to side and the gun is waggling in turn (very impressive) Perhaps I should say 'How does the man in the apache aim the gatling gun under the cockpit at the target?. Another thought , how does the marshaller know the gun is not armed when the Apache lands, or do they just wheel out another one?