GPA-37

 Course Directing Group - A Weapons Directing Analog Computer system built by General Electric Corporation, Heavy Military Electronic Equipment Department at Syracuse in conjunction with Air Research and Development Command Rome Air Development Center and the Electronics Research Laboratories of Columbia University. The first GPA-37 Radar Course Directing Equipment was installed at the Verona Test Site on 13 Dec 1955. The first operational data link test flight took place on an F-86D fighter interceptor aircraft on 28 Dec 1955. GPA-37s were established at ten Air Force long-range radar sites in the late 1950s to automate the manual Ground Control Intercept (GCI) mission against Soviet Manned Bomber attacks with the U.S. Army NIKE Missile Master System. Additional systems were established at Keesler Air Force Base for maintenance training and at Tyndall Air Force Base for Weapons Controller Training. An additional sixteen sites were identified to provide a backup to SAGE direction centers.

The GPA-37 had three major component groups:

With all three major groups, the weapons controller could direct the interceptor aircraft directly to the target with computer commands (Automatic Intercept) or voice commands (Manual Intercept).

Post SAGE Implementation
The implementation of the SAGE system brought fears that the loss of one or two Direction Centers could open up wide expanses of the country to attack and a number of Radar stations were selected to receive the GPA-37s as a backup system. From the Jan-Jun 1961 NORAD/CONAD History:
 * "When work on a plan for emergency backup to SAGE was begun in mid-1960, NORAD asked USAF ADC to put a freeze order on the scheduled release of GPA-37's to the ground stations. This manual control equipment would be needed in the expanded Mode III operation:


 * Following the November 1960 meeting of NORAD region and headquarters officers on the backup plan, NORAD trimmed its requirement to 16 stations, thus enabling GEEIA to begin removal of GPA-37's where they were not needed. At the same time, NORAD asked that GPA-37's be re-installed in two stations. Additional guidance was provided the regions in early 1961 on the retaining of plotting boards, air-ground transceivers, and other manual equipment.


 * In May 1961, USAF ADC recommended that the GPA-37 program be reduced to GPA-23's. NORAD's initial reaction was to disagree and to insist that the original program now incorporated in the 10 April Manual Backup Plan be adhered to. However, subsequent strong assurance by ADC that the GPA-23 proposal would afford equal operational capability at considerably less expense, changed NORAD's point of view. On 29 June, NORAD concurred in the substitution of the GPA- 23's for the GPA-37's."

See Also:
 * SAGE System
 * Permanent System Radar Sites
 * Pinetree Line

Sources:
 * MIL-HDBK-162A, 15 Dec 1965.
 * Jan-Jun 1961 NORAD/CONAD History Pdf
 * Forty Years of Research and Development at Griffiss Air Force Base Pdf, page 28.
 * Forty Years of Research and Development at Griffiss Air Force Base Pdf, page 28.

Links:
 * Radomes - Radar Equipment
 * Wikipedia - GPA-37