Manassas Air Force Station Manassas Air Force Station ( ADC ID : P - 55 NORAD ID : Z - 55 ) is a closed United States Air Force General Surveillance Radar station . It is located west of Dale City , Virginia . It was closed in 1965 . History . Manassas AFS was established as one of twenty - eight stations built as part of the second segment of the permanent Air Defense Command radar 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 . The 647th Aircraft Control and Warning Squadron began operating AN / FPS - 3 and AN / CPS - 4 radars at what was initially designated Quantico in March 1952 , due to it being situated at the northeast corner of the Quantico Marine Corps Base . It assumed coverage from the temporary " Lashup " site L - 14 at Fort Meade , Maryland in 1955 , 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 . The AN / FPS - 3 remained active until 1962 . In July 1957 , the name of the station was officially changed to Manassas Air Force Station . In 1958 AN / FPS - 6 A and AN / FPS - 6B radars took over height - finder chores . During 1959 Manassas AFS joined the Semi Automatic Ground Environment ( SAGE ) system , initially feeding data to DC - 04 at Fort Lee AFS , Virginia . After joining , the squadron was re - designated as the 647th Radar Squadron ( SAGE ) on 1 October 1959 . 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 . Manassas AFS was upgraded to an AN / FPS - 35 radar in 1961 , but problems prevented operations . It became operational in 1962 , and was tested to determine if it could detect missile launchings . The radar detected Polaris and Minuteman missile launches from Cape Canaveral on June 28 , 1962 . Additional tests revealed the AN / FPS - 35 radar had marginal value for missile detection . The AN / FPS - 3 was then retired . In 1963 an AN / FPS - 26 A replaced the AN / FPS - 6A height - finder radar . On 31 July 1963 , the site was redesignated as NORAD ID Z - 55 . In addition to the main facility , Manassas operated several unmanned AN / FPS - 14 Gap Filler sites The site was removed from service on 25 June 1965 . Reportedly , the FPS - 35 radar sail was then sent to Fortuna AFS , North Dakota , to replace the one there which had been destroyed in a fierce wind storm a year earlier . The Manassas GATR site at Independent Hill , VA was retained as site R - 20 and manned by the 770th AC & W Squadron , Operating Location " A " , and continued in operation until 1976 . Today , the former Manassas Air Force Station is an administrative and logistics center for the Prince William County School District . The area remains fenced and many of the former Air Force buildings are in use , along with the housing area . The large AN / FPS - 35 search radar tower remains , as well as the foundations for the other towers , although the towers themselves were removed several years ago . Air Force units and assignments . Units : Assignments :