OTD in 1961—less than four days after President John F. Kennedy's inauguration—a B-52G bomber on airborne alert over North Carolina suffered a massive fuel leak, caught fire, and exploded approaching Seymour Johnson AFB. As it broke up, two 3.8-Megaton B39 Mod 2 H-bombs fell out. 
As the weapons broke free, three of four arming safety devices in one of the bombs were activated, causing it to run through all but one step of the arming sequence as it plunged to earth. Only a single "simple, dynamo-technology, low voltage switch" kept it from detonating.
Unlike the first bomb, the second bomb's parachute did not deploy. It broke up as it penetrated the sandy clay soil at about 700mph, ~.75 miles from where the first bomb landed, in tobacco and cotton fields about 12 miles north of Goldsboro. This bomb was also partially armed.
On impact, both the primary and the secondary smashed through the nosecone and burrowed deeper into the ground. Extensive excavation efforts to recover both began immediately after the accident but were slowed by freezing temperatures, unexploded high explosives, and groundwater.
Much of the primary was found 18-feet-deep on Jan. 28; the remainder was recovered the next day. The plutonium pit was discovered intact on Jan. 30. The secondary was never located and was estimated to be 170-190 feet deep. A gov't easement over the site prevents further digging.
In 2018, former explosive ordnance disposal technician Lt. Jack ReVelle (USAF, ret.) talked with the BBC about locating, defusing, and salvaging the two thermonuclear bombs involved in this nearly catastrophic Broken Arrow accident. bbc.co.uk/programmes/w3c…
After completing his work in North Carolina, the Air Force ReVelle to Christmas Island (Kiritimati), where he witnessed the final 25 US atmospheric nuclear weapons tests in 1962. He now suffers from a rare form of blood cancer. issuu.com/brandosu/docs/…
Last week, another retired USAF explosive ordnance disposal technician, Earl Smith, told a Rotary Club audience in Alabama that ReVelle had unfairly taken credit for the work he and other lower-ranking EODs had done to locate, defuse, and recover the bombs.moultonadvertiser.com/news/local/art…
As this simple simulation shows (and depending on the wind patterns the day of the accident), if even one of these nuclear weapons had exploded, it would have devastated eastern North Carolina and much of the eastern seaboard, changing US history forever. nuclearsecrecy.com/nukemap/?&kt=4…
Here's a good clip about the 1961 Goldsboro Broken Arrow excerpted from the official 2010 Sandia National Laboratories documentary, "Always/Never: The Quest for Nuclear Safety, Control, and Survivability."
