Ajo Air Force Station

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Ajo Air Force Station (1959-1969) - A Cold War Air Force Radar Station first established in 1958 on Childs Mountain near the town of Ajo, Pima County, Arizona. Named Ajo Air Force Station after the location. Initially assigned a Permanent ID of TM-181, later a Sage ID of Z-181 and a JSS ID of J-29A. Abandoned as an Air Force Station in 1969 and turned over to the FAA. Now known as Ajo FAA Radar Site.


Established in January 1958 and became operational in 1958 as Ajo Air Force Station manned by the 612th AC&W Squadron. The station initially had both a Ground-Control Intercept (GCI) and early warning mission. The early warning mission involved tracking and identifying all aircraft entering their airspace while the GCI mission involved guiding Air Force interceptors to any identified enemy aircraft. Controllers at the station vectored fighter aircraft at the correct course and speed to intercept enemy aircraft using voice commands via ground-to-air radio.

Initial equipment included the FPS-20 search radar and an FPS-6A height-finder radar.

SAGE System Transition

The transition of the manual GCI system to the automated SAGE system began with the installation of the FST-2 coordinate data transmitter and search radar upgrades. The FST-2 equipment digitized the radar returns and transmitted the digital returns to the SAGE direction center. Under the SAGE System, interceptor aircraft were directed to their targets by the direction center computers and controllers, greatly reducing the need for local controllers and equipment at every radar station.

The FST-2 was a very large digital system using vacuum tube technology. Over 6900 vacuum tubes were used in each FST-2 requiring 21 air-conditioned cabinets, 40 tons of air conditioning, 43.5 kva of prime power, and usually a large new addition to the operations building. The FST-2B modification added two more cabinets but with newer solid-state (transistor) technology to process coded responses from aircraft transponders.

SAGE System Operation

The site began operation as a SAGE site on 1 May 1961 initially feeding the Luke SAGE Direction Center DC-21. The search radar was upgraded to an FPS-7C and an FPS-26 height-finder radar was installed.

Ajo Air Force Station was Inactivated on 31 Dec 1969.

Gap Filler Radars

Ajo AFS was responsible for the maintenance of one remote unattended gap-filler radar site. The unattended gap filler sites were placed in locations where the main search radar lacked coverage. These sites were equipped with short range FPS-14 or FPS-18 search radars and FST-1 Coordinate Data transmitters that sent digitized radar target data to a SAGE direction center and to the main radar site. Both the radar set and the FST-1 were dual channel to increase site up time. Maintenance teams were dispatched for regularly scheduled maintenance or when fault indicators on the FSW-1 remote monitoring equipment suggested the site had problems. The FSW-1 also allowed remote operation of specific functions such as channel changes for the radar and for the FST-1, it also allowed remote operation of the diesel generators at the gap filler site. The Ajo AFS gap-filler radar was located at Covered Wells, Arizona.

Ajo AFS Gap Filler Radar Sites (edit list)
ADC NORAD Location State Type From To GPS Notes
TM-181B Z-181B Covered Wells Arizona FPS-18, FST-1 Dec 1959 Dec 1960 32.18139,

Physical Plant

The physical plant of the site was divided into the main site, a cantonment area, a housing area, and a radio site. It was described as one of the most expensive of the AC&W sites built, costing some $7.4 million dollars for the 100 or so structures constructed. The main site housed the operations buildings, the radar towers, and the backup generators. The cantonment area housed the enlisted barracks, the bachelor officer's quarters, the orderly room, the dining hall, the motor pool, and other support buildings. Apart from the main site was a housing area for critical married personnel. Ajo had a large married personnel housing area by AC&W site standards with 27 family housing units. A separate Ground to Air Transmitter/Receiver (GATR) radio site housed the radio equipment for directing aircraft intercepts.

Ajo AFS Major Equipment List
Search Radar HF Radar Data Systems
Unit Designations
  • 612th Aircraft Control & Warning (AC&W) Squadron (1957-1961)
  • 612th Radar Squadron (SAGE) (1961-1969)
612th Assignments
  • Activated as 612th AC&W Squadron 8 Mar 1957 at Kirtland AFB, NM, assigned to the 34th AD.
  • Moved to Luke-Williams Range, AZ in Jan 1958.
  • Transferred to Los Angeles ADS 1 Jan 1960.
  • Transferred to Phoenix ADS 1 May 1961.
  • Redesignated from AC&W Sq to 612th Radar Sq (SAGE) 15 Oct 1961.
  • Transferred to 27th AD 1 Apr 1966.
  • Inactivated 31 Dec 1969.

Ajo Air Force Station Partial Commanders List (edit list)
Assumed Relieved Rank Name Cullum Notes
1957-06~ Major Cassidy, Edward G. N/A
1958~ 1958-03~ Lt Colonel Catlin, James N/A
1958-03~ Captain Keysar, Wayne C. N/A
1960-01~ Major Boyd, Robert W. N/A
1967~ 1968-07-15 Major McKinney, Raymond J. N/A
1968-07-15 Lt Colonel Cragin, Robert P. N/A

Current Status

Abandoned as an Air Force Station 1969 and left to the elements. The station's 27 housing units were removed to Gila Bend. In 1994 most of the remaining site buildings were torn down and the site was restored to a natural state by the National Park Service. Only the FPS-26 radar tower remained with the Air Force and FAA maintaining some equipment supporting the Luke-Williams range and radio relay equipment. The upper site was taken over by the FAA in 2000 as a Joint Use radar site and currently has an ARSR-4 3D radar installed. See Ajo FAA Radar Site.

Location: Childs Mountain near Ajo in Pima County, Arizona.

Maps & Images

Lat: 32.43111 Long: -112.945

  • Multi Maps from ACME
  • Maps from Bing
  • Maps from Google
  • Elevation: .....'

See Also:


  • Cornett, Lloyd H. & Johnson, Mildred W., A Handbook of Aerospace Defense Organization (1946-1980), Office of History ADC, Peterson AFB, Colorado, 31 Dec 1980, 179 pages, Pdf, page 154.
  • Winkler, David F., Searching the Skies: the Legacy of the United States Cold War Defense Radar Program, USAF Hq Air Combat Command, 1997, 192 pages, Pdf, page 99.


Fortification ID:

  • AZ0001 - Ajo Air Force Station

Visited: No

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