Historic California Posts, Camps,Station and Airfields
San Ysidro Gap Filler Annex P-76B
Typical AN/FPS-14 Gap Filler Radar
"During the late 1950s another area of progress was the development and deployment of AN/FPS-14 and AN/FPS-18 gap-filler radars. Having a range of around sixty-five miles, these radars were placed in areas where it was thought enemy aircraft could fly low to avoid detection by the longer-range radars of the permanent and mobile radar networks. Gap-filler radar deployment peaked in December 1960 at 131 sites throughout the continental United States. Because the introduction of gap-filler radars alleviated the need for civilians to scan the skies for enemy bombers, the ADC disestablished the Ground Observer Corps on January 31, 1959."
Searching The Skies
USAF Air Combat Command
June, 1997
Typical floorplan of a Gap Filler Annex
US Army Corps of Engineers Los Angeles District History (1991)
The former San Ysidro Gap Filler Annex P-76B was located on a parcel of land located south of Highway 117 and east of Interstate 805 on Otay Mesa Road, approximately 16 miles southeast of San Diego. The San Ysidro Gap Filler Annex was acquired by the US Air Force to be used as an unmanned radar gap filler station for Mount Laguna Air Force Station. The land was acquired fee simple by declaration of taking (No. LA-48) from Samuel G. Goodwin, et ux, on 19 February 1958. The site consisted of 2.64 acres.

The San Ysidro Gap Filler Annex was used as an unmanned radar gap filler station by the U.S. Air Force. Improvements, according to the Report of Excess Real Property submitted to the General Services Administration (GSA) by the U.S. Army Corps of Engineers District, Los Angeles, dated 24 January 1962, include the following:
The date of construction is not known. There is no evidence that the area was under other than Air Force control during the period of Department of Defense (DOD) ownership and use.

The site was reported excess to the General Services Administration on 24 January 1962 by the U.S. Army Engineer District, Los Angeles. The Air Force terminated the ownership of the site by transferring the parcel to the City of San Diego on 14 October 1963 by method of quitclaim. The site is presently used as a communications facility (police, etc.) by the city of San Diego. The block building, access road, concrete walks, and tower foundation are still present based on a site visit on 3 December 1987.
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Updated 8 February 2016