The incident occurred near the Thule Airbase in the Danish territory of Greenland, which is the US Air Force’s northernmost base. The US made an agreement with Denmark to build a base in Greenland during World War II, while Denmark was occupied by Germany.
During the Cold War, the US was concerned over a possible Soviet attack across the North Pole, thus in 1961 US strategic bombers were deployed to the Thule base. It was called Operation Chrome Dome (1961-1968), during which B-52 bombers armed with thermonuclear weapons remained on continuous airborne alerts, flying routes to points along the Soviet border.
On January 21, 1968, a B-52 aircraft commanded by Captain John Haug took off for a mission from Thule. Among the people aboard there was also a mandatory third pilot, Major Alfred D’Mario, and a substitute navigator.
Before take-off, D’Mario placed several cushions on top of a heating vent under the instructor navigator’s seat. About seven hours into flight, the cushions caught fire. The cockpit was soon filled with smoke. The crew could not put out the fire with the extinguishers and so the captain told the crew to abandon the plane.
Co-pilot Leonard Svitenko did not have his ejection seat and tried to leave the aircraft through one of the lower hatches, but sustained fatal head injuries. Haug and D’Mario successfully parachuted onto the ground.
The uncontrolled bomber crashed onto the sea ice in North Star Bay. The conventional components of four 1.1 megaton B28FI hydrogen bombs detonated on impact, causing radioactive contamination over a large area. The radioactive elements included plutonium, uranium, americium and tritium. Contaminated components were scattered over a three-mile area.
Project Crested Ice
Weather conditions at the site were extreme. The average temperature was —40 degrees Celsius, at times dropping to —60. Winds reached 40 meters per second. The operation was conducted in Artic darkness.
The contaminated ice and snow was collected by graders, loaded into wooden boxes and delivered to a nuclear reservation in South Carolina. A total of 6,700 cubic meters of contaminated snow, ice and weapon debris were collected.
In August 1968, the US sent a Star III mini-submarine to look for weapon debris. The secondary of one of the bombs was found almost intact. The secondaries of two other bombs were recovered in pieces. The fourth bomb was not found. Specialists suggest it was buried under debris in deep sea and cannot be recovered.