As far as nuclear weaponry goes, there’s really no such thing as a minor accident. I mean, we’re talking about three and a half tons of uranium and plutonium capable of annihilating everything within 20 square miles of its path; the slope between mishap and catastrophe is steep and slippery.  The consequences of an accidental detonation would be devastating to hundreds of thousands of people both in the blast zone and those within the path of its radioactive fall-out.

A thermonuclear bomb is definitely not something you’d want to just lose track of, but astonishingly, on this date in 1958, that’s exactly what happened.

Image Source: Lindsay Magnum, NPR

It was the thick of Cold War, a full decade before the first anti-proliferation treaty, and Air Force pilots were running a training simulation from Homestead AFB in Florida. The purpose of the mission was to test the reaction time of F-86 fighter pilots stationed at Charleston AFB. Three B-47s ran the mission, and one of them was fitted with a Mark 15 hydrogen bomb that had been “safed” by removing the active plutonium trigger. The only reason it was included at all was so the bomber could realistically mimic the speed and maneuvers of an actual Soviet threat.

All seemed to be going well. The waiting F-86 pilots scrambled to meet the B-47s as they came into Charleston’s airspace, but suddenly two of the planes collided, leaving the pilot hauling the hydrogen bomb no choice but to attempt an emergency landing, ditching the bomb into the water before he did. Luckily, both pilots survived.

There was no explosion as the bomb hit the water, indicating it remained intact. Still, despite the relatively shallow waters of coastal Tybee Island, Georgia, subsequent searches failed to locate and retrieve the weapon. After two and a half months of searching, the military gave up.

So, just how dangerous is it to have a probably plutonium-less thermonuclear weapon just hanging out in a coastal bay? That’s a question up for some debate, and the position you take probably depends on just how much you trust the government.

Although some chose not to believe the Air Force’s position that the bomb was “safed” in the first place, there’s a good deal of evidence to suggest they’re telling the truth. Not only does the pre-crash paperwork specify it was a simulated bomb, but records show that removal and replacement of the plutonium core was standard procedure.

The true danger probably lies not with the possibility of a massive blast, especially since decades worth of salt water would have compromised the electronic components needed for one, but with the the uranium that the bomb contains.  Some have voices concerned that someone could use uranium to create a bomb of their own, but modern scientists view that as unlikely.  The bomb is currently believed to be buried under 5-15 feet of silt, which helps keep it stable and unlikely to corrode and seep into the aquifer.

According to a 2008 article from NPR, the Air Force’s position is that the bomb – wherever it may be – is safer just where it is.

“In a 2001 report on the search and recovery of the bomb, the Air Force said that if the bomb is still intact, the risk associated with the spread of heavy metals is low. If it’s left undisturbed, the explosive in the bomb poses no hazard, the report said. It went on to say that an ‘intact explosive would pose a serious explosion hazard to personnel and the environment if disturbed by a recovery attempt.’ ” 

So, although the Tybee Bomb may not be as big of a mystery or threat as it once seemed, it’s hardly the only missing member of our nation’s nuclear arsenal – in fact, dozens of incidents in the past seven decades have led to a number of missing bombs, dotting the waterways of the world.

Probably.