B-52 is flying over Thule on a Thule Monitor mission. It maintains constant visual contact with the American base in northwest Greenland, considered a primary target by the Soviets. The plane is loaded with four Mark-28 nuclear bombs. The co-pilot has placed foam rubber behind his seat for comfort. After a few hours, he feels cold and turns on the cabin heater, which draws in hot air from the engines, right behind his seat, triggering a fire due to the foam rubber. The crew leaves the plane, which passes over Thule, makes a 180-degree turn, and crashes into the Arctic pack ice at 1,000 km/h in a fireball. The high explosives in the four thermonuclear bombs explode on impact without causing nuclear explosions. The fire burns for five hours until it is extinguished by the unbroken Arctic pack ice. Eisenhower’s on-point safe tests of the atomic warheads were money well spent: had they exploded, they would have destroyed Thule, possibly prompting NORAD to consider a Soviet nuclear attack. The search for the bomb pieces lasted eight months, as many had penetrated the ice, which then refroze. All parts of the four bombs were recovered, in pieces, including the uranium and plutonium, except for a small portion of uranium from one of the four bombs, which was never found, despite searches also on the seabed. The day after the Thule accident, the airborne alert program was definitively terminated: the risks of having atomic bombs on board were no longer justified.
