A Mark 15 Nuclear Bomb Dropped By the US Air Force Was Lost Off the Coast of Tybee Island

In the waters off Tybee Island, near Savannah, Georgia, there's a lost Mark 15 nuclear bomb that was dropped by a US Air Force aircraft during an emergency situation in the 1950s. It's believed to be waiting to be either detonated or discovered, sitting at the bottom of Wassaw Sound

That's where the concern lies. Although initially there were claims that the explosive's nuclear capsule was removed, documents later showed that it's still inside the container. This means the Mark 15 is still a potential threat to those living nearby.

Mid-air collision over Tybee Island

On February 5, 1958, while performing a simulated combat mission exercise, a Boeing B-47 Stratojet was involved in a mid-air collision with a North American F-86 Sabre . The B-47, having taken off from Homestead Air Force Base , Florida, was carrying a two-man crew, as well as a 7,600-pound Mark 15 nuclear bomb.

The F-86's pilot, Lt. Clarence Stewart, hadn't seen the B-47 on his radar and descended directly on top of it. The crash between the two caused the left wing of the fighter jet to completely rip off, while the bomber's fuel tanks suffered heavy damage. Stewart was able to eject before his aircraft crashed, while the pilot of the B-47, Lt. Col. Howard Richardson, sought the closest landing base. Despite the damages to the bomber, the B-47 remained airborne. After dropping 18,000 feet, Richardson regained control.

As for the nuclear bomb onboard the aircraft, he granted the crew's request to jettison it, to prevent it from exploding during the emergency landing. The bomb was dropped from 7,200 feet , over the shores of Tybee Island. The pilot and crew reported no explosion upon it meeting the water, and they were able to successfully land the damaged B-47 at Hunter Army Airfield , Georgia.

For his actions, Richardson was awarded the Distinguished Flying Cross.

A search force was sent to find the bomb

The day after the collision, the search for the missing bomb was started by the US Air Force's 2700th Explosive Ordnance Disposal Squadron, along with 100 US Navy personnel. The operation took place off the coast of Tybee Island, in Wassaw Sound. Using handheld sonar devices and conducting meticulous cable sweeps, the search effort lasted for almost 10 weeks. However, on April 16, the military announced they'd been unable to locate the explosive.

In 2001, the Department of Energy conducted a hydrographic survey of Wassaw Sound that suggested the whereabouts of the Mark 15. The survey suggested that the bomb was buried beneath five to 15 feet of silt. The military was happy to accept this as the explosive's relative location.

Was the Mark 15 nuclear?

Ever since its disappearance, experts have argued over whether the weapon was nuclear or not. If it had a plutonium core, then it was a fully-functional nuclear weapon. If not, then the core was replaced with a dummy, making it non-nuclear, but still capable of producing a conventional explosion.

The Air Force assured the public that the Mark 15's "nuclear capsule" was removed prior to the flight and fitted with a simulated 150-pound cap made of lead. Strategic Air Command documents reinforced this sentiment, explaining that test flights in February 1958 weren't authorized to fly with nuclear capsules fitted into their bombs.

For a long time, this explanation was accepted. However, in 1994, a previously-classified document featuring the transcript from the 1966 Congressional testimony of then-Assistant Secretary of Defense W.J. Howard became unclassified, which contradicted what the Air Force had assured the public for years.

Speaking to the US Congressional Joint Committee on Atomic Energy, Howard confessed the Mark 15 was a "complete, fully functional bomb with a nuclear capsule," containing a plutonium trigger. If Howard's testimony is correct, then the bomb may still cause significant damage to the surrounding area, if detonated. The explosion would include a fireball reaching over a mile and thermal radiation detection as far as 10 miles in all directions.

Yet another search is launched

With this new information, Air Force veteran Lt. Col. Derek Duke privately conducted a new search for the missing nuclear bomb in 2004. He and his team trawled the Wassaw Sound area and measured the levels of radiation in the water with a Geiger counter.

Their search discovered that, near the top of Tybee Island, there were levels of radiation four times higher than naturally-occurring radiation, suggesting that, if the bomb were nuclear, the Mark 15 was located nearby. By finding out where the radiation levels were elevated, they were able to map out and triangulate an area about the size of a football field.

However, a further investigation into the area by the Air Force determined that the higher levels of radiation were naturally occurring, the result of the natural deposits of monazite in the sand. As such, the location of the missing Mark 15 remains a mystery.

Best to leave the nuclear bomb alone

The Air Force is content with leaving the bomb's location a mystery, and officials have assured residents in the surrounding area that it poses no threat, so long as it's left alone. An "intact explosive would pose a serious explosion hazard to personnel and the environment if disturbed by a recovery attempt," they stated .

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The next time you go diving near Tybee Island, keep an eye out for the 12-foot long, 7,600-pound Mark 15 nuclear bomb with the serial number 47782. If you spot it, leave the sleeping beast alone!