A secret document, published in declassified form for the first time by the Guardian today, reveals that the US Air Force came dramatically close to detonating an atom bomb over North Carolina that would have been 260 times more powerful than the device that devastated Hiroshima.

The document, obtained by the investigative journalist Eric Schlosser under the Freedom of Information Act, gives the first conclusive evidence that the US was narrowly spared a disaster of monumental proportions when two Mark 39 hydrogen bombs were accidentally dropped over Goldsboro, North Carolina on 23 January 1961. The bombs fell to earth after a B-52 bomber broke up in mid-air, and one of the devices behaved precisely as a nuclear weapon was designed to behave in warfare: its parachute opened, its trigger mechanisms engaged, and only one low-voltage switch prevented untold carnage.

Each bomb carried a payload of 4 megatons – the equivalent of 4 million tons of TNT explosive. Had the device detonated, lethal fallout could have been deposited over Washington, Baltimore, Philadelphia and as far north as New York city – putting millions of lives at risk.

Though there has been persistent speculation about how narrow the Goldsboro escape was, the US government has repeatedly publicly denied that its nuclear arsenal has ever put Americans’ lives in jeopardy through safety flaws. But in the newly-published document, a senior engineer in the Sandia national laboratories responsible for the mechanical safety of nuclear weapons concludes that “one simple, dynamo-technology, low voltage switch stood between the United States and a major catastrophe”…”It would have been bad news – in spades,” he wrote…

Jones found that of the four safety mechanisms in the Faro bomb, designed to prevent unintended detonation, three failed to operate properly. When the bomb hit the ground, a firing signal was sent to the nuclear core of the device, and it was only that final, highly vulnerable switch that averted calamity. “The MK 39 Mod 2 bomb did not possess adequate safety for the airborne alert role in the B-52,” Jones concludes.

The document was uncovered by Schlosser as part of his research into his new book on the nuclear arms race, Command and Control. Using freedom of information, he discovered that at least 700 “significant” accidents and incidents involving 1,250 nuclear weapons were recorded between 1950 and 1968 alone.

A significant portion of the crap we are fed about classifying military and spy tales appears to be in place to keep anyone from discovering what bumbling idiots we have running our government, our military.