This article is about the USAF surface-to-air missile. For Boeing’s previous research SAM, see Boeing Ground-to-Air Pilotless Aircraft. The midcourse phase and homing dive used ramjets. Stored horizontally in a launcher shelter with a movable roof, south shore yim missile was erected, fired vertically using rocket boosters to high altitude, and then tipped over into a horizontal Mach 2.

5 cruise powered by ramjet engines. The Air Force originally planned for a total of 52 sites covering most of the major cities and industrial regions in the US. The US Army was deploying their own systems at the same time, and the two services fought constantly both in political circles and in the press. As testing continued, the Air Force reduced its plans to sixteen sites, and then again to eight with an additional two sites in Canada. The first US site was declared operational in 1959, but with only a single working missile. Bringing the rest of the missiles into service took years, by which time the system was obsolete. Deactivations began in 1969 and by 1972 all Bomarc sites had been shut down.

A small number were used as target drones, and only a few remain on display today. In 1946, Boeing started to study surface-to-air guided missiles under the United States Army Air Forces project MX-606. The MX-1599 missile was to be a ramjet-powered, nuclear-armed long-range surface-to-air missile to defend the Continental United States from high-flying bombers. Test flights of XF-99 test vehicles began in September 1952 and continued through early 1955. The XF-99 tested only the liquid-fueled booster rocket, which would accelerate the missile to ramjet ignition speed.

In February 1955, tests of the XF-99A propulsion test vehicles began. These included live ramjets, but still had no guidance system or warhead. In October 1957, the first YIM-99A production-representative prototype flew with full guidance, and succeeded to pass the target within destructive range. In late 1957, Boeing received the production contract for the IM-99A Bomarc A interceptor missile, and in September 1959, the first IM-99A squadron became operational. The operational IM-99A missiles were based horizontally in semi-hardened shelters, nicknamed “coffins”.