The SAGE system was a network linking Air Force (and later FAA) General Surveillance Radar stations into a centralized center for Air Defense, intended to provide early warning and response for a Soviet nuclear attack. The Ground Air Transmitting Receiving (GATR) Site (R-18) for communications was located at approximately 1.1 miles souh-southwest from the SAGE building. Normally the GATR site was connected by a pair of buried telephone cables, with a backup connection of dual telephone cables overhead.
DC-18 was initially under the San Francisco Air Defense Sector (SFADS), established on 15 February 1959. DC-18 and the SFADS was inactivated on 1 August 1963 as part of an ADC consolidation and reorganization, with its assigned units assigned to other ADC Sectors. The GATR was reassigned to Mill Valley AFS (Z-38) as an annex designated OL-A, 666th Radar Squadron. Today the large SAGE building is now building 2145, housing the 9th Reconnaissance Technical Squadron; the GATR was inactivated in 1980 and the building is now part of a Skeet-shooting range.