Ballistic Missile Early Warning System

The Ballistic Missile Early Warning System, also called BMEWS or the 474L System, was a United States Air Force Cold War radar, computer and communications network built to detect a mass ballistic missile attack launched over the northern approaches to North America. Its twelve radars, built starting in 1958 and operational by 1961, were designed to give fifteen to twenty five minutes of warning and also fed satellite tracking data to the Space Track program. Sites generally paired a long range AN/FPS-50 radar to scan for and detect missiles as early as possible with a highly accurate AN/FPS-49 monopulse radar to track individual targets, with data first processed on an IBM 709 and later on duplicated IBM 7090 processors. BMEWS was replaced by the Solid State Phased Array Radar System in 2001.