 The USAF received Phantoms as the result of Defense Secretary Robert McNamara 's push to create a unified fighter for all branches of the military . After an F @-@ 4B won the " Operation Highspeed " fly @-@ off against the Convair F @-@ 106 Delta Dart , the USAF borrowed two Naval F @-@ 4Bs , temporarily designating them F @-@ 110A " Spectre " in January 1962 , and developed requirements for their own version . Unlike the navy 's focus on interception , the USAF emphasized a fighter @-@ bomber role . With McNamara 's unification of designations on 18 September 1962 , the Phantom became the F @-@ 4 with the naval version designated F @-@ 4B and USAF F @-@ 4C . The first air force Phantom flew on 27 May 1963 , exceeding Mach 2 on its maiden flight . 
