Fallon Air Force Station

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Fallon Air Force Station (1956-1975) - A Cold War Air Force Radar Station first established in 1956 on Fallon Naval Air Station, Churchill County, Nevada. Initially assigned a Permanent ID of SM-156 and later a Sage ID of Z-156. Abandoned as an Air Force Station in 1975 and is now operated by the FAA as Fallon NAS FAA Radar Site.

Fallon Air Force Station SAGE Site with FPS-35 Tower and SAGE Operations Building


Fallon AFS SAGE Site Backup Power Plant with FPS-35 Tower in the Background

Established in 1956 and became operational in May 1956 as Fallon Air Force Station manned by the 858th 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 MPS-7 search radar and an MPS-14 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

Former Beale SAGE Direction Center DC-18
Tonopah Direction Centers & Sectors
Assigned Direction Center Sector
8 Nov 1954 - 1 Jul 1960 Hamilton Manual Direction Center P-48 28th Air Division
1 Jul 1960 - 15 Sep 1960 Beale SAGE Direction Center DC-18 San Francisco Air Defense Sector
15 Sep 1960 - 1 Apr 1966 Stead SAGE Direction Center DC-16 Reno Air Defense Sector
1 Apr 1966 - 15 Sep 1969 Adair SAGE Direction Center DC-13 26th Air Division
15 Sep 1969 - 19 Nov 1969 Luke SAGE Direction Center DC-21 27th Air Division
19 Nov 1969 - 1 Jul 1970 Luke SAGE Direction Center DC-21 26th Air Division

The site began operation as a SAGE site 1n 1962 initially feeding the Stead SAGE Direction Center DC-16 at Stead AFB, Nevada. The search radar was briefly upgraded to an FPS-3 and then to an FPS-35 in 1963 when the site was moved to the southwest corner of Fallon Naval Air Station. FPS-6 height-finders were installed by 1964. The FPS-35 search radar was replaced with an FPS-66A search radar in the early 1970s. The FPS-66A antenna has a much smaller footprint than the old FPS-35 tower and it is covered with a radome. Around 1965 the site became a joint-use (FAA/ADC) site.

Gap Filler Radars

Fallon 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 Fallon FPS-18 gap-filler site was located at Gabbs, Nevada.

Fallon AFS Gap Filler Radar Sites (edit list)
ADC NORAD Location State Type From To GPS Notes
SM-156A Z-156A Gabbs NV FPS-18, FST-1 1959 1960 38.774444,

BUIC System

Fallon AFS was selected as a BUIC III site and in 1970 the 858th Radar Squadron (SAGE) became the 858th Air Defense Group (BUIC). The BUIC III system provided a backup for a SAGE direction center and provided the ability to display sector-wide radar data on consoles for local weapons controllers. The system duplicated the functionality of the vacuum tube direction center computers with more up-to-date computers and replaced the FST-2 with a more up-to-date coordinate data transmitter, the FYQ-47. As the threat from a Soviet bomber fleet lessened the decision came to mothball the BUIC system in 1974.


Fallon AFS and the 858th were deactivated on 30 Jun 1975.

Fallon NAS FAA Radar Site

Around 1965 the Fallon site became a joint-use (FAA/ADC) site and as a part of that conversion, the FPS-35 search radar was replaced with an FPS-66A search radar in the early 1970s in preparation for the FAA to assume maintenance of the search radar.

A FYQ-47 Common Digitizer was probably placed in service by February 1973 when the USAF/FAA FST-2 to FYQ-47 replacement program was completed. By 1990 the site was equipped with a CD-2A Common Digitizer and an FPS-66A search radar. The Fallon CD-2A was scheduled to receive an upgrade kit to implement three-level weather data processing in Jun 1992.

Mode S Beacon System

Mode S Equipment Typical Installation

The Fallon NAS FAA Radar Site was selected in the 1990s to become one of 21 long-range radar sites to have a Mode S radar beacon system installed. The Mode S system allowed operation in the existing beacon modes but added features to improve beacon operation by allowing aircraft identification with a single interrogation and two-way digital communication between controllers and pilots.

Besides the 21 long-range sites, there were other short-range radars to be upgraded for a total of 137 sites on the implementation list. Fallon NAS was #79 on the list, scheduled to receive the Mode S equipment on 30 May 1994. Installation required interfacing with the radar system, addition of a beacon antenna on top of the search radar antenna, a new larger radome, interfacing with the Common Digitizer (CD-2) if installed, additional communication lines and equipment.


The nationwide replacement program converting FAA legacy radar systems to the CARSR radar configuration was completed by 17 Aug 2015 and Fallon NAS FAA Radar Site was a part of that program. Legacy FAA radars underwent a Service Life Extension Program (SLEP) that replaced key components in the vintage ARSR-1, ARSR-2, FPS-20, FPS-66 and FPS-67 radars. The CARSR program replaced legacy klystron radar transmitters with a solid-state transmitter as well as renovating the radar receiver and signal processor. The CARSR modification also included common digitizer functionality making a separate common digitizer unnecessary. The Fallon NAS FAA Radar Site is now operating with the CARSR radar.

The radar site data is now available to the USAF/NORAD Battle Control System-Fixed (BCS-F) operations centers (EADS & WADS) as well as the FAA Oakland ARTCC (ZOA) and adjacent ARTCCs. Other federal agencies have access to the data under the Homeland Security umbrella.

Physical Plant

The operational site of 858th was first located on the south-central part of NAS Fallon as a mobile radar facility. As fixed equipment became necessary for SAGE integration new radar facilities and an operations building was located about 1.25 miles west of the old site in the southwest corner of the base.

The physical plant included a separate Air Force Housing area, a squadron cantonment area, the main operations area, and a separate GATR radio site.

Fallon AFS Major Equipment List
Search Radar HF Radar Data Systems IFF/SIF/Beacon
858th Unit Designations
  • 858th Aircraft Control & Warning (AC&W) Squadron (1956-1962)
  • 858th Radar Squadron (SAGE) (1962-1970)
  • 858th Air Defense Group (BUIC) (1970-1974)
858th Assignments

Current Status

Now operated by the FAA as Fallon NAS FAA Radar Site a JSS data tied site on Fallon NAS, Churchill County, Nevada.

Location: Fallon NAS, Churchill County, Nevada.

Maps & Images

Lat: 39.40528 Long: -118.72206

  • Multi Maps from ACME
  • Maps from Bing
  • Maps from Google
  • Elevation: 3,934'

GPS Locations:

See Also:



Fortification ID:

  • NV0035 - Fallon Air Force Station
  • NV0036 - Fallon NAS FAA Radar Site

Visited: 19 Mar 2014

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