GE AN/GPA-37 Course Directing Group

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For the "miniature SAGE" intercept system, see General Electric AN/GPA-73 Air Weapons Control System.

The GE AN/GPA-37 Course Directing Group[1] was a USAF Cold War air defense command, control, and coordination system for weapons direction (ground-controlled interception).[2] During Air Defense Command's "Control Capability Improvement Program"[1] to improve command guidance of manned aircraft, the AN/GPA-37 was "developed by the General Electric Heavy Military Electronic Equipment Department at Syracuse in conjunction with...Rome Air Development Center and the Electronics Research Laboratories of Columbia University."[3] Used to process radar data, the system was to "track a potential enemy aircraft and direct intercepters[verification needed] [sic] into a position from which they can make their automatic firing runs", the system included the:[3]

  • AN/GPA-34 Converter Group for processing radar data,
  • AN/GPA-23 Computing-Tracking Group with analog computer for "automatically providing the solution of the interception problem" (developed at Columbia University),[4]
  • AN/GKA-1 Flight Control Group for "automatic communications between ground installation and intercepter" (e.g., "verbally to the pilot"),
  • and for modified systems, AN/GPA-67 Time Division Data Link equipment** for input of the SAGE TDDL data stream into the Flight Control Group[5]:36

The Secretary of Defense concurred on October 30, 1956, for deployment of the AN/GPA-37[5] as an interim[6] "pre-SAGE semiautomatic intercept system"[7] to Air Defense Direction Centers (ADDCs)[8]:11 (e.g., in ADC's Zone of the Interior)[4] prior to fielding the SAGE System with AN/FST-2, AN/FSQ-7, & AN/FSQ-8 equipment.

The forecast dates for NCCs with both AN/FSG-1 & AN/GPA-37 systems ranged from November 1959 for Fort Lawton (Seattle Air Defense Sector) to October 1960 Gibbsboro (Philadelphia).[9]

After the planned Super Combat Centers for 10 underground air defense sites were cancelled in 1960,* the AN/GPA-37 was redeployed as the dispersed Back-Up Interceptor Control (BUIC)[5] prior to development of BUIC II (Burroughs AN/GSA-51 Radar Course Directing Group). BUIC was for degraded SAGE operations when "a DC and the adjacent DC's were all out and responsibility had to be exercised by the division commander through the NORAD control center".[5] By 1959, the military technical school for the AN/GPA-73 was at Keesler Air Force Base.[10]


*"General Partridge replied on 2 July 1959 that the NORAD requirement for a non-SAGE back-up method of exercising operational control of all weapons was valid until the SCC system was operational and could not be withdrawn.[11]

**NCCs were at Missile Masters for "the Los Angeles, Seattle, Chicago, Detroit, Boston, Washington-Baltimore, New York, and Buffalo areas. NORAD added San Francisco, at which there was no NCC, but at which, NORAD said, one would be established. ... NORAD required an AN/GPA-67 at each of these NCC's so as to provide a capability for control of Time Division Data Link-equipped interceptors when the sector converted to TDDL."[11]

  1. ^ a b IRISNUM 00463903
  2. ^ "Installation of AN/GPA-37 Automatic Ground Controlled Interception"
  3. ^ a b "Automatic G.C.I.". Flight Global: 618 & p. 619. May 10, 1957. 
  4. ^ a b Division 6 - Lincoln Laboratory...Biweekly Report for 29 July 1955 (Memorandum 6M-3797) A symposium on the AN/GPA-37 system was held at Rome Air Development Center on 26 and 27 July. This system Involves a technique for ground control of interceptors by use of the Tracker-Computer (AN/GPA-23), which was developed at Columbia University. Field tests on this system will begin in November 1955; It would be worthwhile to follow the activ- ities of these field tests. ... The Systems Office has obtained more detailed information about the Radar Course Directing Group, AN/GPA-37, at a symposium held at RADC on 26 and 27 July. The GPA-37 is intended for backup air defense for SAGE and will be operated at the Heavy Radar P-sites in the Zone of Interior
  5. ^ a b c d NORAD/CONAD Historical Summary: July–December 1958 "In September 1956, CONAD proposed to the JCS the collocation of the Missile Master and the Air Force's AN/GPA-37 in ten areas. The Office of the Secretary ot Defense concurred on 30 October 1956."
  6. ^ Condit, Kenneth W. (1992 [1971 classified volume]). "Chapter 15: Continental Defense". The Joint Chiefs of Staff and National Policy: 1955-1956 (Report). Volume VI of History of the Joint Chiefs of Staff. Washington, DC: Historical Office, Joint Staff. c. Modify existing manual aircraft control and warning system so that it will have the capacity to handle a mass raid by completing installation of interim equipment (AN/GPS-T2 and AN/GPA-37).  Check date values in: |date= (help)
  7. ^ McMullen, R. F. (15 Feb 80). History of Air Defense Weapons 1946–1962 (Report). ADC Historical Study No. 14. Historical Division, Office of information, HQ ADC. pp. 211, 306. the GPA-37 electronic heart of an advanced system of ground controlled interception which immediately preceded SAGE, and with SAGE itself. ... The AN/GPA-35 [sic] was a pre-SAGE control system that would be used until SAGE was ready.  Check date values in: |date= (help);
  8. ^ Preface by Buss, L. H.--NORAD Director of Command History (1 October 1958). North American Air Defense Command Historical Summary: January — June 1958 (8 chapters & Appendix) (Report). Directorate of Command History: Office of Information Services. p. 21. Retrieved 2013-04-10. 
  9. ^ NORAD CONAD Historical Summary: January–June 1959 " Both CAA and AMB were incorporated in a new agency, the Federal Aviation Agency which officially began functioning on 31 December 1958 ... RCAF would be responsible for constructing the Ottawa SCC building and for insuring a beneficial occupancy date of 15 September 1961. The AN/FSQ-7A computer would be installed by IBM and by late 1962 RCAF personnel would man the SCC under the direction of the responsible test agencies. The SCC was scheduled to become fully operational on 1 July 1963. ... On 17 July 1959, USAF directed the BMEWS Project Office to prepare an engineering proposal for an interim BMEWS display facility. ... In a paper dated 11 February 1959, the JCS charged the Air Force Chief of Staff with responsibility for the [Cheyenne Mountain] COC project. ... site A, Cheyenne Mountain, in the "NORAD Site Investigation Feasibility Report," dated January 1959, prepared by the firm of Parsons, Brinckerhoff, Hall und MacDon ald for the Army Corps of Engineers. ... The esti mated construction cost of the NORAD COC installation is $28,540,000. ... 19 May 1959 on re quirements of the NORAD Command Control System. ... National Space Surveillance Control Center...7 January with a directive to ARDC to build a research and development interim NSSCC at Han scom Field, Massachusetts. ... At NORAD Headquarters, a space surveillance control center committee was established on 12 February 1959. ... Maintain liaison with the ARDC Space Detection and Surveillance Filter Center being established at Laurence G. Hanscom Field ... ARDC Space Detection and Surveillance Filter Center being established at Laurence G. Hanscom Field ... "
  10. ^
  11. ^ a b NORAD CONAD Historical Summary: July–December 1959 "On 18 March 1960, the JCS advised NORAD that they had approved cancellation of the SCC program for the U.S."