Almaden Air Force Station
|This article needs additional citations for verification. (December 2012) (Learn how and when to remove this template message)|
|Almaden Air Force Station|
|Part of Air Defense Command (ADC)|
Almaden AFS from San Jose
|Type||Air Force Station|
|Code||ADC ID: M-96, NORAD ID: Z-96|
|Controlled by||United States Air Force|
|Garrison||682nd Aircraft Control and Warning Squadron|
Almaden Air Force Station was established in 1954 by Air Defense Command as one of a planned deployment of forty-four Mobile radar stations to support the permanent ADC Radar network in the United States sited around the perimeter of the country. This deployment was projected to be operational by mid-1952. Funding, constant site changes, construction, and equipment delivery delayed deployment. Almaden AFS was located on the summit of Mount Umunhum in the Santa Cruz Mountains, the station is a few miles south of San Jose, California and sits 3,486 feet (1,063 m) above Almaden Valley. Great difficulties were encountered in construction at this site. During fiscal year 1957, the Air Defense Command held up construction due to funding shortfalls.
The 682nd Aircraft Control and Warning Squadron was assigned to the new station by the 28th Air Division on September 1, 1957. It became operational on March 21, 1958, equipped with AN/FPS-20 and twin AN/FPS-6 radars. In 1961, the site received an AN/FPS-24 radar, but could test the radar only on a not-to-interfere basis with television transmissions. This radar became operational in 1962, and the AN/FPS-20 was removed soon afterward and its concrete foundation was re-purposed as a helipad. In 1963, an AN/FPS-90 replaced the second AN/FPS-6 height-finder and the original AN/FPS-6 was removed and replaced with an AN/MPS-14 height finder adjacent to the AN/FPS-24 radar tower.
During 1961, Almaden AFS joined the Semi Automatic Ground Environment (SAGE) system, feeding data to DC-18 at Beale AFB, California. After joining, the squadron was re-designated as the "682d Radar Squadron (SAGE)". In 1963, the SAGE site was switched to DC-17 at Norton AFB, California. Also on 31 July 1963, the site was re-designated as NORAD ID Z-96. In 1979 Almaden AFS came under Tactical Air Command (TAC) jurisdiction with the inactivation of Aerospace Defense Command and the creation of ADTAC. Operations ceased on 1 April 1980 as a result of budget restrictions, and the general phase down of air defense radar stations.
The station operated a Ground-to-Air Transmitter-Receiver (GATR) atop the summit of Mount Umunhum until the completion of the AN/FPS-24 radar in 1962. To eliminate radio frequency interference from the AN/FPS-24 radar, the GATR was then moved one mile west to the summit of Mount Thayer. The original GATR building was subsequently converted to supply storage and ultimately as a training room facility.
The station today is abandoned and off-limits to the general public. It was acquired in 1986 by the Midpeninsula Regional Open Space District (MROSD). The site is now a part of the Sierra Azul Open Space Preserve although it is not yet open to the public because of environmental hazards (asbestos, black mold, and lead-based paint). The MROSD estimates it will take at least US$13.1 million to clean up the base for public use.
On May 10, 2016, the Santa Clara County Board of Supervisors voted unanimously to list the Almaden AFS AN/FPS-24 Radar Tower on the County Heritage Resource Inventory, thus giving it official historic status and demolition protection. 
Air Force units and assignments
- 682d Aircraft Control and Warning Squadron (moved to Almaden AFS, 1 September 1957)
- Activated at Geiger Field, Washington on 1 December 1953 (not manned or equipped)
- Moved to Kirtland AFB, New Mexico on 1 January 1954 (not manned or equipped)
- Moved to Hamilton AFB, California on 13 July 1954 (not manned or equipped)
- Assigned to Mount Umunhum on 1 September 1957 (Squadron activated with minimal staffing)
- Squadron Operational on 21 March 1958
- Re-designated 682d Radar Squadron (SAGE) on 15 January 1961
- Re-designated 682d Radar Squadron on 1 February 1974
- Squadron Inactivated on 1 April 1980
- 28th Air Division, 1 September 1957
- San Francisco Air Defense Sector, 1 July 1960
- Los Angeles Air Defense Sector, 1 August 1963
- 26th Air Division, 1 April 1966
- 27th Air Division, 15 September 1969
- 26th Air Division, 19 November 1969 - 1 April 1980
- List of USAF Aerospace Defense Command General Surveillance Radar Stations
- List of United States Air Force aircraft control and warning squadrons
This article incorporates public domain material from the Air Force Historical Research Agency document "A Handbook of Aerospace Defense Organization, 1946–1980".
- "682nd Radar Sqdn. Almaden AFS, CA Welcome Brochure". U.S. Air Force. p. 2. Retrieved February 27, 2012.
- "Mt. Umunhum Notice of Area Closures" (PDF). Midpeninsula Regional Open Space District. Retrieved 2012-03-01.
- "Mount Umunhum cube to stay: Cold War relic gets historic designation". www.mercurynews.com. Retrieved 2016-05-23.
- Cornett, Lloyd H; Johnson, Mildred W (1980). A Handbook of Aerospace Defense Organization, 1946–1980 (PDF). Peterson AFB, CO: Office of History, Aerospace Defense Center. p. 160.
- Winkler, David F.; Webster, Julie L (1997). Searching the skies: The legacy of the United States Cold War Defense Radar Program (PDF). Champaign, IL: US Army Construction Engineering Research Laboratories. LCCN 97020912.