The Boeing CIM-10 BOMARC (IM-99 Weapon System prior to September 1962) was a supersonic ramjet-powered long-range surface-to-air missile (SAM) fielded during the Cold War for the air defense of North America. In addition to being the first operational long-range SAM, it was also the only SAM ever deployed by the USAF. Stored horizontally in a launcher shelter with a movable roof, the missile was erected, launched vertically using rocket boosters to high altitude, and then tipped over into a horizontal Mach 2.5 flight, powered by the ramjets. Controlled from the ground for most of its flight, when it reached the target area it was commanded to begin a dive, activating an onboard radar-homing seeker for terminal guidance. A radar proximity fuse detonated the warhead, either a large conventional explosive or a nuclear warhead. The Air Force originally planned for a total of 52 sites covering most of the major cities and industrial regions in the U.S., but the Army’s Nike Hercules ended up covering many of those areas. As testing continued, the Air Force reduced its plans to 16 sites, and then to just eight, with two more sites in Canada. The first U.S. site was declared operational in 1959. Boeing started to study surface-to-air guided missiles under project MX-606 in 1946. By 1950, Boeing had launched more than 100 test rockets in various configurations, and because these tests were very promising, Boeing received a USAF contract in 1949 to develop a pilotless interceptor (a term then used by the USAF for air-defense guided missiles) under project MX-1599. 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. The Michigan Aerospace Research Center (MARC) joined the project soon afterward, and this gave the new missile its name: BOMARC (the BO from Boeing). In 1951, the USAF decided to emphasize its point of view that missiles were just pilotless aircraft by assigning aircraft designators to its missile projects, and anti-aircraft missiles received F-for-Fighter designations. The BOMARC thus became the F-99. In August 1955, the USAF discontinued the use of aircraft-like type designators for missiles, and the XF-99A and YF-99A became XIM-99A and YIM-99A, respectively. In October 1957, the first YIM-99A production 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 interceptor missile, and in September 1959, the first IM-99A squadron became operational. The IM-99A had an operational radius of 200 miles and was designed to fly at Mach 2.5-2.8 at a cruising altitude of 60,000 feet. The liquid-fuel booster of the BOMARC-A had several drawbacks. It took two minutes to fuel before launch, which could be a long time in high-speed intercepts, and its hypergolic propellants (nitric acid and hydrazine) were very dangerous to handle, leading to several serious accidents. As soon as high-thrust solid-fuel rockets became a reality, the USAF began to develop a new solid-fueled BOMARC variant, the IM-99B (BOMARC-B). The first successful IM-99B flight was in July 1960. Because the new booster took up less space inside the missile, more ramjet fuel could be carried, increasing the range from 200 to 430 miles. All BOMARC-B missiles were equipped with the W-40 nuclear warhead. In June 1961, the first IM-99B squadron became operational, and BOMARC-B quickly replaced most BOMARC-A missiles. On 23 March 1961, a BOMARC-B successfully intercepted a Regulus II cruise missile flying at 100,000 feet, thus achieving the highest interception in the world up to that date. Boeing built 570 BOMARC missiles between 1957 and 1964, 269 “A” models and 301 “B” models. Up until September 1958, BOMARC testing was conducted at Cape Canaveral, but at that time the testing and training program was relocated to a new facility on Santa Rosa Island, just across the water from Eglin AFB’s Hurlburt Field. To operate the facility and to provide training and operational evaluations, ADC established the 4751 ADW there. The first launch from Santa Rosa Island took place on 15 January 1959. From that time on, all BOMARC personnel were trained by the 4751st. The BOMARC suffered just one serious accident. On 7 June 1960, a BOMARC-A with a nuclear warhead caught fire at McGuire AFB after its on-board helium tank exploded. While the explosives did not detonate, the heat melted the warhead and released plutonium, which the fire crews ended up spreading. The Air Force and the AEC cleaned up the site and covered it with concrete. The site remained in operation for several years following the fire. Since its closure in 1972, the area has remained off limits, primarily due to low levels of plutonium contamination. By the early 1970s, the BOMARC weapons system was considered obsolete because during the 1960s the threat had shifted from waves of manned bombers to showers of ballistic missiles. Deactivations began in 1969 and by 1972 all BOMARC sites had been shut down. Many of the missiles ended up being used as target drones, and a few were placed on static display.