5. Several B-52s were lost to accidents over the next several decades
In January 1957, a B-52 operating out of Maine crashed after the airframe broke up a flight, killing all but one of the crew. The co-pilot successfully bailed out of the stricken airplane. The bomber had been on a training mission and had not been carrying nuclear weapons. But several B-52 crashes and accidents have involved nuclear weapons. During the 1950s and 1960s, SAC operated the Airborne Alert Program. B-52 bombers carrying nuclear weapons operated in various theaters around the globe, refueled by tanker aircraft, ready to initiate a nuclear strike if needed. The United States had nuclear bombs in the air at all times. It was the Air Force’s leg of the nuclear triad, which consisted of US land-based ballistic missiles, the bombers, and the Navy’s submarine-launched ballistic missiles. At least two B-52 crashes led to nuclear contamination.
In 1966 a B-52 collided with a refueling tanker near Palomares, Spain. The B-52 carried four nuclear bombs, which used conventional explosives to detonate a nuclear explosion. Two of the bombs had their conventional explosives detonate, which did not cause a thermonuclear reaction, but which did scatter plutonium and uranium over a wide area. In 1968 another B-52 carrying nuclear weapons crashed in Greenland. Again, widespread contamination occurred, which the United States cleaned up at considerable political and financial cost (the Spanish accident cleanup continued into the 21srt century). Following the Greenland incident, SAC discontinued the airborne alert program, at least officially. By the mid-1960s the B-52 had a new mission, one for which it had not been designed, but which it continues to the present day.