The Hughes AN/ASG-18 Fire Control System was a prototype airborne radar/combination system for the planned North American XF-108 Rapier interceptor aircraft for the United States Air Force. The US's first pulse doppler radar, the system had look-down/shoot-down capability and could track one target at a time. This was paired with an infrared search and track (IRST) system. Range of the radar was estimated at between 200 and 300 miles (322 to 482 km), with reliable detection of bomber-sized targets at 100 miles. The installation itself was massive, weighing 2,100 lb (953 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.