The B-29 bomber came screaming out of the afternoon sky over Okinawa on August 9, 1945, firing off every flare it could. From what the harried control tower at the recently-acquired military base could tell from the signals, the plane was out of fuel, on fire, had wounded crewmen and was afflicted with just about everything else that could happen to a plane in battle.

Hitting the ground too fast, the bomber bounced 25 feet in the air and roared to a halt after narrowly missing rows of planes loaded with firebombs. Fire trucks, ambulances and all emergency personnel on hand scrambled to meet the plane as the crew jumped out. They were immediately taken to base headquarters, where the commander demanded to know who they were and what they were doing at Okinawa unannounced.

Ellen Bradbury and Sandra Blakeslee write about what happened next for the Bulletin of the Atomic Sciences. “We are the 509, Bockscar,” replied the plane’s weaponeer, Navy Commander Frederick L. Ashworth. “We dropped an atomic bomb on Nagasaki. Sir, I think we were a little off target.”

There are many accounts of what happened during the flight to drop the nuclear bomb that ended World War II, but as Bradbury and Blakeslee write, Ashworth’s is one that has gone mostly unreported until recently. Ashworth was a friend and neighbor of Bradbury and told her stories about the flight to Nagasaki over the years.

According to Ashworth’s account, just about everything that could have gone wrong with the Nagasaki run did. From an engineer messing up the wiring on the bomb’s detonator, to miscommunications between the men who manned the Bockscar, to Ashworth ordering the pilot to switch targets to Nagasaki after nearly being shot down above the city of Kokura, the story of the second bombing could have had a radically different ending, write Bradbury and Blakeslee.

Perhaps the most harrowing of Ashworth’s stories came about three hours into the flight. The plane was cruising 39,000 feet above the Pacific when he was woken from a nap by a panicked assistant weaponeer, Bradbury and Blakeslee report. The men had apparently flipped two switches by accident as they armed the bomb — switches that triggered the detonation sequence. They managed to turn off the sequence and go back to their mission, dropping the Fat Man weapon at 11:01 a.m.

Though the real death toll may never be known, between 60,000 and 80,000 people are thought to have died in Nagasaki. Ironically, the problems the men aboard the Bockscar faced during the bombing may actually have saved the lives of some of Nagasaki's citizens. According to the Atomic Heritage Foundation, the crew failed to drop the bomb at the precise target in the city – instead, the bomb landed in the Urakami Valley, confining the blast and saving a portion of the city from annihilation.