Template:SLBM-FSS-7

Responding to contract proposals for an interim missile launch detection system, AVCO Corporation's plan to modify existing FPS-26 height finder radars at six prime SAGE System radar sites and to install a new one near Laredo AFB, Texas was approved in July 1965. Radars were to be located at the following sites:



It was expected that the Avco 474N Submarine Launched Ballistic Missile (SLBM) Detection and Warning System would be operational by the end of 1967. The system included GSQ-89 data processing equipment and the modified radars were called FSS-7's. The radars provided seaward coverage of about 750 nm and with three basic modes of operation: search, acquisition, and track.

In operation, a warning and impact message was generated for trans­mission to the central processor at the Cheyenne Mountain 425L System Complex within 50 sec­onds from the initial detection of a missile. The Cheyenne Mountain Complex then relayed 474N data to SAC, the National Military Command Center (NMCC), and the Alternate NMCC over BMEWS circuits. At maximum detection range, this provided approxi­mately 7 to 10 minutes of warning.