( CNN ) -- On a January night in 1961 , a U.S. Air Force bomber broke in half while flying over eastern North Carolina . From the belly of the B-52 fell two bombs -- two nuclear bombs that hit the ground near the city of Goldsboro . A disaster worse than the devastation wrought in Hiroshima and Nagasaki could have befallen the United States that night . But it did n't , thanks to a series of fortunate missteps . Declassified documents that the National Security Archive released this week offered new details about the incident . The blaring headline read : `` Multi-Megaton Bomb Was Virtually 'Armed ' When It Crashed to Earth . '' Or , as Secretary of Defense Robert McNamara put it back then , `` By the slightest margin of chance , literally the failure of two wires to cross , a nuclear explosion was averted . '' It 's difficult to calculate the destruction those bombs might have caused had they detonated in North Carolina . What might 've been . The website , nuclearsecrecy.com , allows users to simulate nuclear explosions . It says that one bomb the size of the two that fell in 1961 would emit thermal radiation over a 15-mile radius . Wind conditions , of course , could change that . The blast today , with populations in the area at their current level , would kill more than 60,000 people and injure more 54,000 , though the website warns that calculating casualties is problematic , and the numbers do not include those killed and injured by fallout . It 's also worth noting that North Carolina 's 1961 total population was 47 % of what it is today , so if you apply that percentage to the numbers , the death toll is 28,000 with 26,000 people injured -- a far cry from those killed by smaller bombs on the more densely populated cities of Hiroshima and Nagasaki in Japan . University of California-Los Angeles researchers estimate that , respectively , Hiroshima and Nagasaki had populations of about 330,000 and 250,000 when they were bombed in August 1945 . By that December , the cities ' death tolls included , by conservative estimates , at least 90,000 and 60,000 people . Wayne County , North Carolina , which includes Goldsboro , had a population of about 84,000 in 1961 . The state capital , Raleigh , is 50 miles northwest of Goldsboro , and Fayetteville -- home of the Army 's massive Fort Bragg -- is 60 miles southwest . The Goldsboro incident . The B-52 was flying over North Carolina on January 24 , 1961 , when it suffered a `` failure of the right wing , '' the report said . As the plane broke apart , the two bombs plummeted toward the ground . The parachute opened on one ; it did n't on the other . `` The impact of the aircraft breakup initiated the fuzing sequence for both bombs , '' the summary of the documents said . In other words , both weapons came alarmingly close to detonating . Weapon 1 , the bomb whose parachute opened , landed intact . Fortunately , the safing pins that provided power from a generator to the weapon had been yanked -- preventing it from going off . Weapon 2 , the second bomb with the unopened parachute , landed in a free fall . The impact of the crash put it in the `` armed '' setting . Fortunately -- once again -- it damaged another part of the bomb needed to initiate an explosion . While it 's unclear how frequently these types of accidents have occurred , the Defense Department has disclosed 32 accidents involving nuclear weapons between 1950 and 1980 . There are at least 21 declassified accounts between 1950 and 1968 of aircraft-related incidents in which nuclear weapons were lost , accidentally dropped , jettisoned for safety reasons or on board planes that crashed . The accidents occurred in various U.S. states , Greenland , Spain , Morocco and England , and over the Pacific and Atlantic oceans and the Mediterranean Sea . Another five accidents occurred when planes were taxiing or parked . Two months after the close call in Goldsboro , another B-52 was flying in the western United States when the cabin depressurized and the crew ejected , leaving the pilot to steer the bomber away from populated areas , according to a DOD document . The plane crashed in Yuba City , California , but safety devices prevented the two onboard nuclear weapons from detonating . Catastrophe averted . The Goldsboro incident was first detailed last year in the book `` Command and Control '' by Eric Schlosser . The documents released this week provided additional chilling details . Eight crew members were aboard the plane that night . Five survived the crash . `` I could see three or four other chutes against the glow of the wreckage , '' recounted the co-pilot , Maj. Richard Rardin , according to an account published by the University of North Carolina . `` I hit some trees . I had a fix on some lights and started walking . '' The MK39 bombs weighed 10,000 pounds and their explosive yield was 3.8 megatons . Compare that to the bombs dropped in Hiroshima and Nagasaki : They were 0.01 and 0.02 megatons . But Rardin did n't know then what a catastrophe had been avoided . `` My biggest difficulty getting back was the various and sundry dogs I encountered on the road . '' Hiroshima atomic bomb attraction more popular than ever . Kennedy meets atomic bomb survivors in Nagasaki . By the numbers : Atomic bombs . CNN 's Eliott C. McLaughlin and Dave Alsup contributed to this report .
Goldsboro one of 32 pre-1980 accidents involving nukes . Weeks after Goldsboro , there was another close call in California . The weapons came alarmingly close to detonation . They were far more powerful than the bombs dropped in Japan .