Sault Sainte Marie Air Force Station Sault Sainte Marie Air Force Station ( ADC ID : P - 66 , NORAD ID : Z - 66 ) is a closed United States Air Force General Surveillance Radar station . It is located south - southwest of Sault Sainte Marie , Michigan . It was closed in 1979 . History . In November 1950 , the 753d Aircraft Control and Warning Squadron was activated by Air Defense Command at a temporary " Lashup " radar site located at Sault Sainte Marie Airport , to provide radar defense coverage for the area . It was equipped with AN / TPS - 1 B and 1C radars , the site being designated by ADC as L - 21 . In late 1951 Air Defense Command selected Sault Sainte Marie as one of twenty - eight radar stations built as part of the second segment of the permanent radar surveillance network . Prompted by the start of the Korean War , on July 11 , 1950 , the Secretary of the Air Force asked the Secretary of Defense for approval to expedite construction of the second segment of the permanent network . Receiving the Defense Secretary ’ s approval on July 21 , the Air Force directed the Corps of Engineers to proceed with construction . On 1 January 1952 the 753d AC & W Squadron began operating AN / FPS - 3 and AN / FPS - 5 radars at the permanent site , being designated as " P - 66 " by ADC , and initially the station functioned as a Ground - Control Intercept ( GCI ) and warning station . As a GCI station , the squadron ' s role was to guide interceptor aircraft toward unidentified intruders picked up on the unit ' s radar scopes . During 1956 the Air Force replaced the AN / FPS - 5 with an AN / FPS - 6 unit . In 1958 the AN / FPS - 3 was replaced by an AN / FPS - 20 search radar , and soon received a second height - finder radar , an AN / FPS - 6 B . During 1960 Sault Sainte Marie AFS joined the Semi Automatic Ground Environment ( SAGE ) system , initially feeding data to DC - 14 at K . I . Sawyer AFB , Michigan . After joining , the squadron was re - designated as the 753d Radar Squadron ( SAGE ) on 15 July 1960 . The radar squadron provided information 24 / 7 the SAGE Direction Center where it was analyzed to determine range , direction altitude speed and whether or not aircraft were friendly or hostile . In 1963 , the station was switched to the SAGE Data Center DC - 06 at Custer AFS , Michigan . In 1963 an AN / FPS - 35 search radar replaced the AN / FPS - 20 A . The AN / FPS - 6 was removed in 1963 , and the AN / FPS - 6B was modified to an AN / FPS - 90 . On 31 July 1963 , the site was redesignated as NORAD ID Z - 66 . In 1964 an AN / FPS - 26 A height - finder radar was installed . In addition to the main facility , Sault Sainte Marie operated the following AN / FPS - 18 Gap Filler sites : Over the years , the equipment at the station was upgraded or modified to improve the efficiency and accuracy of the information gathered by the radars . Sault Sainte Marie AFS came under Tactical Air Command jurisdiction in October 1979 with the inactivation of Aerospace Defense Command and the formation of ADTAC . The 753rd Radar Squadron was inactivated on 30 October 1979 and Sault Sainte Marie Air Force Station was closed . After the station ' s closure , sections of the AN / FPS - 35 radar antenna were sent to Montauk AFS in 1980 to replace corroded sections of the antenna there . Today the former Air Force Housing site is occupied as private homes . The operational area used as an auto junkyard and other small businesses in the former USAF buildings . The radar towers remain , and the remains of the center section of the large FPS - 35 sail lies on the ground where it was apparently dropped when it was removed , the base of the antenna remains on top of the large tower . Air Force units and assignments . Units . Assignments :