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:

Early Missile/Satellite Radar Locations

SAGE ID	Location	State	Equipment	14th MWS	Notes
	Moorestown AFS	NJ	Prototype FPS-49	Det 1
Z-37	Point Arena AFS	CA	Not Modified		Replaced by Mill Valley AFS
Z-38	Mill Valley AFS	CA	Modified FPS-26	Det 3	Replaced Point Arena AFS
Z-65	Charleston AFS	ME	Modified FPS-26	Det 6
Z-76	Mount Laguna AFS	CA	Modified FPS-26	Det 4
Z-l00	Mount Hebo AFS	OR	Modified FPS-26	Det 2
Z-115	Fort Fisher AFS	NC	Modified FPS-26	Det 5
Z-129	MacDill AFB	FL	Modified FPS-26	Det 7
Z-230	Laredo AFS	TX	New FSS-7	Det 8

416N System Diagram.

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.