Cottonwood Air Force Station
Cottonwood Air Force Station (1958-1965) - A Cold War Air Force Radar Station first established in 1958 near Cottonwood, Idaho County, Idaho. Named Cottonwood Air Force Station after the location. Initially assigned a Permanent ID of SM-150 and later a Sage ID of Z-150. Abandoned in 1965.
The radar site was accepted by the Air Force from the construction contractor in November 1957 and became operational in 1959 as Cottonwood Air Force Station manned by the 822nd AC&W Squadron. Initial radar equipment included the MPS-7 search radar and an MPS-14 height-finder radar, both of these radar sets were temporary mobile versions to be used until more permanent equipment could be installed.
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.
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 Aug 1960 initially feeding the Larson SAGE Direction Center DC-15 using the mobile radar equipment. In 1962 the search radar was upgraded to an FPS-24, an FPS-90 height-finder radar was added to the already installed FPS-6 height finder.
The FPS-24 was one of 12 installed as a part of the SAGE system radars and one of two FPS-24s that were covered by a radome. The massive rotating antenna weighed 85 tons, was 120 feet wide and was installed on an 80-foot steel tower. The antenna rotated on a large 10 foot in diameter central bearing that proved to be unreliable and difficult to replace.
In 1963 the Larson SAGE Direction Center DC-15 closed and control of Cottonwood AFS shifted to the McChord SAGE Direction Center DC-12 on 1 Jun 1963. Control remained with McChord until the site closed in 1965.
Cottonwood 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 Cottonwood AFS gap filler radar was located at Waha, Idaho.
The closure of Cottonwood AFS was announced by the Air Force in November 1964 to take place early in 1965 as a result of defense spending cutbacks. A bearing failure in the FPS-24 antenna pedestal in December 1964 led to a decision not to replace the bearing since the site was already slated for closure and that led to an early shutdown of radar operations at the site. Cottonwood AFS and the 822nd were officially deactivated on 1 Jul 1965.
The physical plant of the site was divided into the main site, a cantonment area, a housing area and a radio site. The main site housed the operations buildings, the radar towers, and the backup generators. The cantonment area, located 4 miles from the main site, housed the enlisted barracks, the bachelor officer's quarters, the orderly room, the dining hall, the motor pool and other support buildings. Located close to town was a small 27 unit housing area for married personnel. A separate Ground to Air Transmitter/Receiver (GATR) radio site housed the radio equipment for directing aircraft intercepts. The Air Force spent over 12.5 million dollars developing the station.
Note: Some entries are from newspaper articles and may be inaccurate.
The cantonment area was used from 1965 to 1972 as a Job Corps Center. The Idaho Department of Corrections acquired the property in 1972 and the site is now known as the Northern Idaho Correctional Institution.
The 10.78-acre main site operations area now just includes the FPS-24 tower, 3 large circular radar tower foundations, one concrete block building and the buildings associated with the radio sites. Most of the operations area is privately owned with portions leased to the FAA for use as a remote air/ground station and to other private concerns. The FPS-24 tower is still standing with in-use communications antennas on the top deck. Of the four FPS-24 steel towers that were built around the country, this is the only one still standing and of the two FPS-24s installations that had radomes, this is the only one remaining. The concrete foundations are all that remains of the other three Cottonwood radar towers. The operations building has been leveled but the foundations remain with the cable troughs exposed. All other buildings have been leveled including the power plant and supply buildings. Both communications sites are intact with improvements and active communications facilities.
Until 2012 the 27 homes in the former USAF housing area near Cottonwood were under State ownership and used by the Bureau of Land Management (BLM) and Forrest Service families. The northeast portion of the housing area, including nine house sites, has been converted into a Bureau of Land Management (BLM) compound. In 2012, the 18 units outside the BLM compound were auctioned off to private interests and are in reasonable repair although several appear empty. The "U" shaped road that went through the housing area is now blocked to thru traffic by the BLM Compound.
Visited: 24 Jun 2017, 1959