GE AN/GPA-73 Radar Course Directing Group

The GE AN/GPA-73 Radar Course Directing Group (mobile version AN/CPA-73) was an air defense command, control, and coordination system of the United States Air Force. It was developed for the Electronic Systems Division 412L Air Weapons Control System (colloq. "AWCS 412L") for weapons direction (ground-controlled interception, GCI, by "Fire Direction and Control Equipment").^: 29 The AN/GPA-73 was used to create a "Base Air Defense Ground Environment" (BADGE II), for which Air Defense Command had recommended the system as "SAGE back-up (Mode Ill) control of BOMARC" in June 1958. When the GPA-73 was emplaced with the AN/FSA-21 Weapons Control Group computer for GCI, the system created a "miniature SAGE" military installation. The GPA-73 could also direct Project Nike surface-to-air missile fire from Nike Integrated Fire Control sites equipped with the "412 Target Designation System" in the Battery Control Van in a space allocated by February 1957 "behind the Acquition Operator [sic]". and the AN/GPA-73.

The 412L Joint Test Force was located at Myrtle Beach Air Force Base in 1963, testing revealed fragility that limited the unit to fixed emplacements, and "Tactical Air Command subsequently rejected the GPA-73 as part of its mobility forces." The 412L equipment supported "Det 1, 17th Air Force [in] the Allied Sector Operations Center III at Börfink", Germany, which had a nuclear bunker where on July 2, 1975, the 615th Aircraft Control and Warning Squadron temporarily stopped 412L operations [for] Constant Keystone modification." Sites with the AN/GPA-73 planned for the Alaska Semi-Automatic Defense System (ALSADS) were cancelled on January 26, 1960,^: 49 and the last "operational 412L equipment" was used by USAFE in Germany.