Despite efforts of some officials within the Air Force to secure a reprieve, the phaseout proceeded on schedule. The last B-58s were retired in January 1970, after which they were placed into storage with the Military Aircraft Storage and Disposition Center (MASDC) at Davis-Monthan Air Force Base. The fleet survived intact until 1977, at which point nearly all remaining aircraft were sold to Southwestern Alloys for disposal. As a weapons system, the B-58 was replaced by the FB-111A. This aircraft was designed for low-altitude attack, to be more flexible with the carriage of conventional weapons, and less expensive to produce and maintain.