The helmet used for the Apache has an IHADS (Integrated Helmet-mounted Aquisition & Data System). Three sensors situated around the cockpit pick up the helmets relative position by sensing the movement of pencil lazers attatched to the helmet. All the pilot has to do is look through the monacle mounted on his helmet (target sighting and flight information are projected on to the monacle), look at a target and (hopefully) the cannon will follow. (please excuse any inaccuracies!)
