The AN/ASG-18 Fire Control System produced by Hughes Aircraft was a prototype airborne fire control radar system for the planned North American XF-108 Rapier interceptor aircraft, and the Lockheed YF-12 for the United States Air Force. It was the US's first Pulse-Doppler radar, giving it look-down/shoot-down capability, and was also the first track while scan radar. This was paired with an infrared search and track (IRST) system. Range of the radar was estimated at between 200–300 mi (320–480 km), with reliable detection of bomber-sized targets at 100 miles (160 km). The installation itself was massive, weighing 2,100 pounds (950 kg), and taking up most of the nose of the aircraft. The system was to be used with the Hughes AIM-47 Falcon missile, which also had a range of about 100 miles.