Development of the Phoenix began in late 1960, after the U.S. Navy's projected F6D Missileer and the associated AAM-N-10 Eagle long-range interception missile had been cancelled. Hughes then started to develop a new long-range missile, designated AAM-N-11 by the Navy, together with the AN/AWG-9 FCS (Fire Control System). The new missile and FCS used technology previously tested by the AIM-47 Falcon and AN/ASG-18, respectively, in the USAF's YF-12A program. The Phoenix/AWG-9 combination was originally intended as the main armament for the F-111B, then planned to become the Navy's new air superiority fighter and long-range interceptor. In June 1963, the AAM-N-11 was redesignated as AIM-54A. Flight tests of XAIM-54A prototypes began in 1965, and the first guided interception succeeded in September 1966. While the Phoenix test program continued, the F-111B was cancelled, and the AIM-54 and AN/AWG-9 were incorporated into the new F-14 Tomcat, which was to take over the role of the F-111B. The first production AIM-54A missiles were delivered in 1973, ready for deployment with the first F-14A squadron in 1974.
An F-14 can carry up to 6 Phoenix missiles, on LAU-93/A (F-14A/B) or LAU-132/A (F-14D) launchers, respectively. The AN/AWG-9 FCS uses a TWS (Track While Scan) pulse-doppler radar, and can track up to 24 targets simultaneously at ranges of up to 240 km (130 nm). Therefore, an F-14 can effectively attack 6 targets simultaneously. When an AIM-54A is launched, its Rocketdyne MK 47 or Aerojet MK 60 solid-fueled rocket motor (in an MXU-637/B propulsion section) propels it to a speed of Mach 4+. For mid-course guidance, the missile's AN/DSQ-26 guidance section employs an autopilot, which gets regular target position updates by semi-active radar tracking. The FCS radar periodically illuminates every target to which a missile has been dispatched. For maximum range, the missile flies an optimized high-altitude trajectory for reduced drag, and the AIM-54A can engage head-on targets at a distance of up to 135 km (72.5 nm). For the final 18200 m (20000 yds) of the interception, the Phoenix switches to active radar homing for high terminal accuracy. Minimum engagement range is about 3.7 km (2 nm), in which case active homing is used from the beginning. The 60 kg (132 lb) MK 82 blast-fragmentation warhead is detonated by a fuzing system consisting of a MK 334 radar proximity, an IR proximity, and an impact fuze.