During the Cold War, the biggest threat was a nuclear strike by the Soviet Union. But, for a brief moment during those tense years, the United States almost nuked itself.
When two Mark 39 hydrogen bombs were accidently dropped over Goldsboro, North Carolina, on January 23, 1961, the United States narrowly avoided a cataclysmic calamity. The bombs were dropped after a US Air Force B-52 bomber split up in mid-air. One of the explosives behaved exactly as intended: its parachute deployed, its trigger mechanisms were activated, and, astonishingly, a single low-voltage switch prevented horrific carnage.
A 24-hour airborne alert operation off the American Atlantic Coast was being carried out by “Keep 19,” a Boeing B-52G-95-BW Stratofortress belonging to the 4241st Strategic Wing. The Strategic Air Command had B-52 bombers equipped with nuclear weapons flying round-the-clock, every day of the week during that period when the United States and the Soviet Union were at war. Pilots Capt. Richard W. Hardin and 1st Lt. Adam C. Mattocks were flying the aircraft under the leadership of Maj. Walter S. Tulloch, U.S. Air Force. Two Mark 39 thermonuclear bombs, each with a yield of 3–4 megatons, were mounted on it.
More than 700 of the Mark 39 thermonuclear bombs, which had two stages and radiation-implosion technology, were built between 1957 and 1959. It was fully fused, which meant that it could explode upon impact with the ground as an airburst, or “lay down,” in which case a sequence of parachute drops would slow the bomb before it touched down on its target, giving the bomber time to escape the blast zone.
The Mark 39 was a relatively light weapon, weighing between 6,500 and 6,750 pounds, with a bomb that was around 12 feet long and almost 3 feet in diameter. The Mark 39 had an explosive yield of 3.8 megatons, which is 250 times more powerful than the Hiroshima bomb and would have been enough to annihilate everyone and everything in a 17-mile radius, or roughly the region inside the Capital Beltway surrounding Washington, DC.
Three days after President John F. Kennedy assumed office, the crew of an air tanker alerted Major Tulloch that the B-52’s right wing was leaking fuel while the aircraft was refuelling in flight. As the B-52 was instructed to return to Seymour Johnson Air Force Base in North Carolina to try an emergency landing, a significant leak occurred, resulting in the loss of more than 5,400 gallons (37,000 pounds) of jet fuel in less than three minutes.
The bomber became more difficult to control as they fell because of the imbalance caused by the excessive fuel load. As the right wing began to shear off, the bomber lost control, and Major Tulloch gave the crew the order to flee the perilous aircraft. Before the B-52 disintegrated and exploded, five crew members exited by the top hatch and one using a ladder. Sadly, three crew members—Majors Shelton and Richards and Sergeant Barnish—were killed, and its wreckage covered an area of around two square miles.
The B-52’s two Mark 39 bombs were unleashed as it disintegrated. One buried itself more than 180 feet deep after crashing into a muddy field at a speed of nearly 700 mph. The parachute safety system on the other bomb worked as anticipated, and it landed almost unharmed, finding hanging from a tree, the parachute saving it from striking the ground.
The military has a code word for an incident like this involving the loss of nuclear weapons called “Broken Arrow.” Some reports claim that five of the six steps (or six of the seven) necessary for a thermonuclear detonation occurred, despite official statements to the contrary.
Although it was difficult to collect the buried bomb, it was mostly found after eight days, including the 92 detonators and conventional explosive “lenses” of the “primary,” or first stage implosion section. The bomb’s actual core, the uranium-235/plutonium-239 “pit,” was discovered on January 29. But the “secondary” was never discovered.
