Whoa. The Guardian reports:
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.Only one of the four safety mechanisms operated properly and prevented detonation, according to the report.