RCAF Station Saint Margarets

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RCAF Station Saint Margarets (1953-1969) - A Cold War Canadian Radar Station first established in 1953 near the town of Saint Margarets in New Brunswick. Initially named RCAF Saint Margarets after the location. Assigned a Permanent ID of C-5 and later a Sage ID of C-5. Abandoned in 1989. Also known as CFB Chatham - St. Margarets Detachment.

CFS Saint Margarets 6 Oct 1971 DND Photo


Construction began in 1950 and the station became operational on 1 Nov 1953 as RCAF Saint Margarets, manned by both the 21 AC&W Squadron and the 2 Air Defence Control Centre (ADCC). The 21 AC&W Squadron operated the radar site while the 2 ADCC operated the 2nd sector control center. The AC&W operations room concentrated on the on-site radar scopes and equipment, passing their track and status information on to the 2 ADCC as did the other radar sites in the sector. These two different operations were consolidated on 18 Mar 1955 into a "one-room" configuration.

21 AC&W Squadron

The station radar site 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 unidentified aircraft. Controllers at the radar station vectored fighter aircraft at the correct course and speed to intercept enemy aircraft using voice commands via ground-to-air radio.

Initial radar equipment included the FPS-3 search radar and a pair of ISG-98 height-finder radars. The search radar was upgraded to an FPS-20 and then to an FPS-508 with two FPS-6B height-finders.

2 Air Defence Control Centre (ADCC)

The ADCC was a large facility, three stories high with a large floor space where a sector-wide horizontal plotting board showed the air traffic sector-wide. On the wall behind the horizontal plotting board was a vertical tote board with track and status information for the entire sector. 2 ADCC also operated its own communications center connected to all the radar sites and air bases in the sector.

SAGE Transition

St. Margarets SAGE/BUIC Operations Area in June 1969.

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.

The site began operation as a SAGE site in September 1962, initially feeding the Topsham SAGE Direction Center DC-05 in Maine until the North Bay SAGE Direction Center DC-31 became operational on 1 Oct 1963.

Gap Fillers

Saint Margarets was planned to have responsibility for the maintenance of some six remote unattended gap-filler radar sites. None of the planned Saint Margarets gap-filler radars became operational.

BUIC System

Saint Margarets became a BUIC I GCI site in 1962 and a BUIC II manual backup site in 1966. It was selected as a BUIC III site and in 1968 the BUIC III system was implemented. The BUIC III system provided a backup for a SAGE direction center with the GSA-51 computer system 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 the more up-to-date GSA-51 computer system 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 United States BUIC system in 1974.

In Canada under BUIC III, St. Margarets was assigned as a BUIC NORAD Control Centre (BNCC) and became operational on 1 Jan 1969. The 34 Radar Squadron at CFS Senneterre became BNCC No. 1 while 21 Radar Squadron at Saint Margaret's was designated as BNCC No. 2. Saint Margarets became the only operational BNCC after CFS Senneterre was placed in standby status and Saint Margarets was solely responsible for backing up the underground North Bay SAGE Direction Center DC-31.

The unsupportable U.S. SAGE Direction Centers were consolidated and closed down in favor of new Regional Operational Control Centers (ROCC) with more modern computers. Canada, as a NORAD partner, chose the same path and the conversion took place between 1980 and 1983. The Canadian ROCCs were fully operational by August 1984 but the BUIC mission at Saint Margaret's ended on 19 Jul 1983 and the station became a Long Range Radar (LRR) surveillance site.

Satellite Tracking and Identification (SITU)

In 1974, St. Margarets was selected as a Satellite Tracking and Identification (SITU) location and by 1976, the SITU was operational. The facility continued operating until its closure in 1989.


In March 1985, the Canadian Minister of National Defence announced the closure of the CADIN/Pinetree Line. Saint Margarets and the 21 Radar Squadron were deactivated on 1 Apr 1988, the 64th anniversary of the Royal Canadian Air Force.

Physical Plant

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 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 small housing area for married personnel.

A separate Ground to Air Transmitter/Receiver (GATR) radio site housed the radio equipment for directing aircraft intercepts. Like most early radar stations, Saint Margarets originally had a radio transmitter site (5 miles away) and a separate radio receiver site (10 miles away) both were used by local controllers for identification and 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.

Saint Margarets AS Major Equipment List
Search Radar HF Radar Data Systems Comm Scopes IFF/SIF
Unit Designations
  • 21 Aircraft Control & Warning (AC&W) Squadron (1953-1958)
  • 21 Radar Squadron (1958-1969)
21 Squadron Assignments
  • 1 Nov 1953 - Operational as 21 Aircraft Control & Warning Squadron.
  • 8 May 1958 - Designated 21 Radar Squadron.
  • 1 April 1988 - Deactivated.
Station Strength including 2 ADCC and 21 AC&W
Personnel 30 Nov 1954 31 May 1955
Officers 33 35
NCOs 44 57
Airmen 170 180
Airwomen 101 72
TOTAL 348 344

Current Status


Location: Saint Margarets in New Brunswick.

Maps & Images

Lat: 46.90917 Long: -65.20917

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

GPS Locations:

See Also:


  • NORAD/CONAD Historical Summary Jan-Dec 1966, dated 1 May 1967, Command History Division, HQ NORAD/CONAD, Unclassified (originally classified Secret), pdf, pages 28-31, Backup Intercept Control Systems


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