By December 1965 NORAD decided to use the Project Space Track "phased-array radar at Eglin AFB…for SLBM surveillance on an "on-call" basis" "at the appropriate DEFCON". By June 1966 the refined FPS-85 plan was for it "to have the capability to operate in the SLBM mode transmissions with the Spacetrack surveillance and tracking modes" Rebuilding of the "separate faces for transmitting and receiving" began in 1967 after the under-construction Eglin FPS-85 was "almost totally destroyed by fire on 5 January 1965". FPS-85 IOC was in 1969, 474N interim operations began in July 1970 (474N IOC was 5 May 1972), and in 1972 20% of Eglin FPS-85 "surveillance capability…became dedicated to search for SLBMs," and new SLBM software was installed in 1975. (the FPS-85 was expanded in 1974).