Miles City Air Force Station

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Miles City Air Force Station (1954-1968) - A Cold War Air Force Radar Station first established in 1954 near Miles City, Custer County, Montana. Named Miles City Air Force Station after the location. The station was built on a portion of the old Fort Keogh military reservation. Initially assigned a Permanent ID of M-98 and later a Sage ID of Z-98. Abandoned in 1968.


Established on 1 Oct 1954 and became operational in 1955 as Miles City Air Force Station manned by the 902nd AC&W Squadron. The station initially had both a Ground-Control Intercept (GCI) and an 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 mobile MPS-7 search radar and an MPS-14 height-finder radar. The MPS-7 search radar was replaced by an FPS-20 in 1958 and that radar was upgraded to an FPS-66 in 1961 and later to an FPS-27. The MPS-14 height-finder was replaced by an FPS-6 in 1961.

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

Former Minot SAGE Direction Center DC-19 now Repurposed.
Miles City SAGE Direction Centers & Sectors
Assigned Direction Center Sector
1 Jan 1961 - 25 Jun 1963 Minot SAGE Direction Center DC-19 Minot Air Defense Sector
25 Jun 1963 - 1 Apr 1966 Malmstrom SAGE Direction Center DC-20 Great Falls Air Defense Sector
1 Apr 1966 - 18 Jun 1968 Malmstrom SAGE Direction Center DC-20 28th Air Division

The site began operation as a SAGE site on 1 Jan 1961 initially feeding the Minot SAGE Direction Center DC-19 at Minot AFB. With the closure of DC-19 in 1963, Miles City was connected to the Malmstrom SAGE Direction Center DC-20 at Malmstrom AFB and remained connected to them until the site closed in 1968.

Gap Fillers

Miles City AFS was responsible for maintaining two remote unattended gap-filler radar sites. The gap-filler sites were placed in locations where the main search radar lacked coverage. 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. Miles City AFS was responsible for the gap-filler sites at Glendive and Brockway Montana.

Miles City AFS Gap Filler Radar Sites (edit list)
ADC NORAD Location State Type From To GPS Notes
M-98A/TM-177A Z-98A Glendive Montana FPS-18, FST-1 1958 1960 47.044167,
M-98B Z-98B Brockway Montana FPS-18, FST-1 1959 1960 47.283611,


The initial closure announcement for Miles City came in November 1964 and cited a closure date by 1 Jul 1967. That date was extended to the end of FY 1969 in January 1967. When the final closure announcement came on 15 Feb 1968 the base had 108 military personnel assigned and 11 civilians employed. Miles City AFS and the 902nd were deactivated on 18 Jun 1968.

Physical Plant

The physical plant of the site was divided into the main site Operations area, a cantonment area, a housing area, and a separate radio site. The main site operations area housed the operations building, the radar towers, tech supply buildings, and the backup generators.

The cantonment area housed the four enlisted barracks, bachelor officer's quarters, orderly room, dining hall, motor pool, recreation hall, NCO Club, and other support structures.

Apart from the main site was a 27-unit housing area for married personnel. Seven units were designated for officers and twenty units for NCOs. The 27 housing units were built in 1958 and included one four-bedroom unit for the commander, six, three-bedroom officers' quarters, and twenty, three-bedroom units for NCOs. Just outside the front gate was a gas station operated by the NCO club.

A separate GATR radio site housed the radio equipment for directing aircraft intercepts. Like most early radar stations, Miles City originally had a radio transmitter site and a separate radio receiver site used by local controllers for voice direction of fighter interceptors to their targets. With the SAGE System, the SAGE Direction centers had the primary task of directing intercepts and the local radio sites were reconfigured, usually into a single site that was known as the Ground to Air Transmitter Receiver (GATR) site. The GATR site communicated with the interceptors from either the local site or the SAGE direction center via voice commands and/or a digital data link.

Miles City AFS Composite Plan.
Miles City AFS Structures (edit list)
Number Building Exists Notes
FPS-20 Tower No
FPS-27 Tower Partial
FPS-6B Tower No
FPS-90 Tower No
1* Operations/FST-2 Partial
3* Tech Supply No
4* Supply Warehouse No
5* Air Police No
6* HQ Orderly Room No
7* Bachelor Officers Quarters (BOQ) No
8* Dining Hall No
9* Dispensary/NCO Club/IEO Office No
10* Gym/Library/Barber/Bx No
11* Motor Pool No
12* Carpenter/IEO Workshop No
13* Telephone Company (Telco) Yes
14* MARS Station No
15* Radio No
16* Pump Plant Ruins
17* Main Gate House No
18* Gas Station No
19* Power Production No
20* Power Production Yes
21* Barracks (BAQ) No
22* Barracks (BAQ) No
23* Barracks (BAQ) No
24* Barracks (BAQ) No
25* GATR Radio Site Yes Remote from main site

* Not the actual building numbers but reference numbers to the plan.

Miles City AFS Major Equipment List
Search Radar HF Radar Data Systems Comm
Unit Designations
  • 902nd Aircraft Control & Warning (AC&W) Squadron (1954-1961)
  • 902nd Radar Squadron (SAGE) (1961-1968)
902nd Assignments
  • 20 May 1953 - Activated at Great Falls AFB, MT, assigned to 29th AD.
  • Fall of 1954 - Moved to Miles City AFS, MT.
  • 1 Jan 1961 - Transferred to Minot ADS. (Minot DC-19)
  • 15 Jul 1961 - Redesignated from AC&W Sq to 902nd Radar Sq (SAGE).
  • 25 Jun 1963 - Transferred to Great Falls ADS. (Malmstrom DC-20)
  • 1 Apr 1966 - Transferred to 28th AD. (Malmstrom DC-20)
  • 18 Jun 1968 - Discontinued.
Miles City Air Force Station Partial Commanders List (edit list)
Assumed Relieved Rank Name Cullum Notes
1957-07-23 Major Steele, William R. N/A
1957-07-23 1960-05 Major Meyer, William S. N/A
1960-07-14 1963-08 Lt Colonel Jehli, Arthur T. N/A
1963-08 Lt. Colonel Blackburn, William R. N/A
Major Knickerbocker, George D. N/A
1968~ 1968-06-18 Lt Colonel Towne, Ralph W. N/A

Current Status

Part of the Fort Keogh Livestock and Range Research Lab (USDA), Montana State University. Some buildings remain. A Highway marker is located on I 94 at the eastbound Hathaway rest stop (zoom out on the map to see the marker location).

All of the housing area homes are gone. Part of the Ops building and parts of the FPS-27 tower remain. All the other radar towers are gone. Nearly all the cantonment buildings have been reduced to just the foundations with a few partial walls still upright. The Telco building seems to be still standing. Access to the site is blocked by a locked gate along the roadway.

Location: Exit 128 on I-94 just west of Miles City, MT.
Now part of Fort Keogh Livestock and Range Research Lab (USDA
Miles City, Custer County, Montana.
Maps & Images

Lat: 46.29667 Long: -105.97861

  • Multi Maps from ACME
  • Maps from Bing
  • Maps from Google
  • Elevation: 2,815'

GPS Locations:

See Also:


  • 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 132.
  • 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 172.
  • USGS Geographic Names Information System (GNIS) Database Entry: 2089511


Fortification ID:

  • MT0140 - Miles City Air Force Station

Visited: No

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