The Air Force deployed the AIM-4 on the F-4D Phantom in May 1967, during the Vietnam War. The Phantom carried the Falcon on its inner pylons. The Falcon's operational record was unimpressive. Because it was designed for use against bombers and had a slow seeker cooling time, the AIM-4 needed up to seven seconds to obtain a target lock. This response time was too slow to be used against maneuvering fighters.