The Yamaha RMAX helicopter powered by a liquid-cooled 2-stroke, 246cc horizontal engine rated at 21hp, capable of covering a distance of about 10 kilometers or a flight time of 90 minutes with a 30 kg effective load capacity and a 10 foot rotor span. One of the crucial functions to control this revolutionary autonomous-flight helicopter is the YACS (Yamaha Altitude Control System). Mounted on the helicopter itself are an altitude sensor, a GPS (Global Positioning System) sensor and a communications modem. Observation equipment, consisting of a digital camera and a digital still camera, are mounted along with three miniature video cameras for navigation purposes. Images from these cameras are sent from the helicopter to the ground station on a realtime basis, where they are viewed on a four-window split screen monitor.