Ground Air Transmit Receive

Ground Air Transmit Receive (GATR) control sites^[1] were the radio stations of a Burroughs 416L SAGE Defense System of the United States Air Force.

They were deployed to automate ground-controlled interception using crewed interceptor aircraft. Generally located near or, in some cases, on an Aerospace Defense Command radar station, a GATR site was used for the Ground to Air Data Link Subsystem to communicate command guidance via HF/VHF/UHF voice and TDDL^[2] to vector F-106 Delta Dart and other suitably equipped aircraft^[3] that had been dispatched by teams in Weapons Direction rooms of SAGE Direction Centers. Maintenance was done by the 304x4 Ground Radio Maintenance career field,^[4] with initial technical training at Keesler Air Force Base.^[5] The sites included the RCA AN/GKA-5 Time Division Data Link (TDDL) equipment,^[6] that fed a two-channel AN/FRT-49 Electronic Guidance Signals Transmitting Set,^[7] employing Varian klystrons^[8] to deliver 20 kilowatts output power (early sites used the 100 watt, single-channel AN/GRT-3 instead.^[9] The aircraft receivers were either Hughes AN/ARR-60 or SLI AN/ARR-61 Airborne Radio Receivers^[10] of the Hughes MA-1 Fire Control System.^[11]

Most GATR/SAGE sites are now Formerly Used Defense Sites (e.g., the 6-acre (2.4 ha) site supported by Oakdale Air Force Station, Pennsylvania) that were closed by the 1995 Base Realignment and Closure Commission.^[12]

The San Francisco Z-38 (Mill Valley) site differed from Manual Air Defense Control Centers that networked Permanent System radar stations, NORAD Control Centers had simpler C³ equipment (e.g., for the "austere SAGE area" in the Zone of the Interior) than the Direction Centers' AN/FSQ-7s such as the General Electric AN/GPA-37 Course Directing Group with AN/GPA-67 Time Division Data Link equipment through transmitters to the AN/ARR-39 "SAGE Datalink Receivers" used in the F-86L Sabre Interceptor, which was the SAGE variant^[10]—an F-86D Sabre Dog with equipment for day/night/all weather operations. For example, by 1965, "Hamilton AFB and Richards-Gebaur AFB…operated as Remote Combat Centers (Hamilton had remote input from Reno Sector and Richards-Gebaur from Sioux City Sector)".^[18]