1958 Tybee Island mid-air collision

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1958 Tybee Island mid-air collision
A Mk 15 nuclear bomb of the type lost when jettisoned after the collision
Midair Collision summary
Date February 5, 1958
Summary Midair collision
Site Tybee Island, Georgia, United States
32°0′N 80°51′W / 32.000°N 80.850°W / 32.000; -80.850Coordinates: 32°0′N 80°51′W / 32.000°N 80.850°W / 32.000; -80.850
First aircraft
Type Boeing B-47
Operator United States Air Force
Registration 51-2349
Fatalities 0
Second aircraft
Type F-86 Sabre
Operator United States Air Force
Crew 1
Survivors 1

The Tybee Island B-47 crash was an incident on February 5, 1958, in which the United States Air Force lost a 7,600-pound (3,400 kg) Mark 15 nuclear bomb in the waters off Tybee Island near Savannah, Georgia, United States. During a practice exercise, the B-47 bomber carrying the bomb collided in midair with an F-86 fighter plane. To protect the aircrew from a possible detonation in the event of a crash, the bomb was jettisoned. Following several unsuccessful searches, the bomb was presumed lost somewhere in Wassaw Sound off the shores of Tybee Island.

Midair collision[edit]

1958 Tybee Island mid-air collision is located in Georgia (U.S. state)
Crash site
Crash site
Atlanta
Atlanta
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Georgia

The B-47 bomber was on a simulated combat mission from Homestead Air Force Base in Florida. It was carrying a single 7,600-pound (3,400 kg) bomb. At about 2:00 AM, the B-47 collided with an F-86. The F-86 crashed, after the pilot ejected from the plane. The damaged B-47 remained airborne, albeit barely.

The crew requested permission to jettison the bomb, in order to reduce weight and prevent the bomb from exploding during an emergency landing. Permission was granted, and the bomb was jettisoned at 7,200 feet (2,200 m) while the bomber was traveling at about 200 knots (370 km/h). The crew did not see an explosion when the bomb struck the sea. They managed to land the B-47 safely at the nearest base, Hunter Air Force Base. The pilot, Colonel Howard Richardson, was awarded the Distinguished Flying Cross after this incident.[1]

Bomb[edit]

Some sources describe the bomb as a functional nuclear weapon, but others describe it as disabled. If the bomb had a plutonium nuclear core installed, it was a fully functional weapon. If the bomb had a dummy core installed, it was incapable of producing a nuclear explosion but could still produce a conventional explosion. The 12-foot (4 m) long Mark 15 bomb weighs 7,600 pounds (3,400 kg) and bears the serial number 47782. It contains 400 pounds (180 kg) of conventional high explosives and highly enriched uranium.[2] The Air Force maintains that the bomb's nuclear capsule, used to initiate the nuclear reaction, was removed before its flight aboard B-47.[3] As noted in the Atomic Energy Commission "Form AL-569 Temporary Custodian Receipt (for maneuvers)", signed by the aircraft commander, the bomb contained a simulated 150-pound cap made of lead.[4] But according to 1966 Congressional testimony by then Assistant Secretary of Defense W.J. Howard, the Tybee Island bomb was a "complete weapon, a bomb with a nuclear capsule," and one of two weapons lost by that time that contained a plutonium trigger.[5][6] Nevertheless, a study of the Strategic Air Command documents indicates that in February 1958, Alert Force test flights (with the older Mark 15 payloads) were not authorized to fly with nuclear capsules on board. Such approval was pending deployment of safer "sealed-pit nuclear capsule" weapons that did not begin deployment until June 1958.[7]

Recovery efforts[edit]

Starting on February 6, 1958, the Air Force 2700th Explosive Ordnance Disposal Squadron and 100 Navy personnel equipped with hand held sonar and galvanic drag and cable sweeps mounted a search. On April 16, the military announced the search had been unsuccessful. Based on a hydrologic survey, the bomb was thought by the Department of Energy to lie buried under 5 to 15 feet (2 to 5 m) of silt at the bottom of Wassaw Sound.[3]

In 2004, retired Air Force Colonel Derek Duke claimed to have narrowed the possible resting spot of the bomb to a small area approximately the size of a football field. He and his partner located the area by trawling in their boat with a Geiger counter in tow. Secondary radioactive particles four times naturally occurring levels were detected and mapped, and the site of radiation origination triangulated.[8][unreliable source?] Subsequent investigations found the source of the radiation was natural.

Ongoing concerns[edit]

The risk of corrosion of the bomb's alloy casing is lessened if it is completely covered in sand. But if part of the casing is exposed to seawater due to the shifting strata in which it is buried, rapid corrosion could occur, as demonstrated in simulation experiments. Eventually, the highly enriched uranium could leach out of the device and enter the aquifer surrounding the continental shelf in that area. Storms, hurricanes, and strong currents frequently shift the sand there.

To date, no undue levels of unnatural radioactive contamination have been detected in the regional Upper Floridan aquifer by the Georgia Department of Natural Resources (over and above the already high levels thought to be due to monazite, a locally occurring sand naturally high in radiation).[9][10]

See also[edit]

Notes[edit]

  1. ^ BBC News, Missing for 50 years - US nuclear bomb (22 June 2009)
  2. ^ "Complete List of All U.S. Nuclear Weapons". Archived from the original on 16 December 2008. Retrieved 11 November 2008. 
  3. ^ a b "Air Force Search & Recovery Assessment of the 1958 Savannah,B-47 Accident". Air Force Nuclear Weapons and Counterproliferation Agency (PDF). 12 April 2001. Retrieved 27 February 2010. 
  4. ^ The Nuclear Information Project, Form AL-569, "Temporary Custodian Receipt (for maneuvers)," to U.S. Atomic Energy Commission, Albuquerque Operations, from James W. Twitty, Col., U.S. Air Force, February 4, 1958. Released under FOIA. (PDF)
  5. ^ CounterPunch.org, When We Almost Nuked Savannah: The Case of the Missing H-Bomb (15 May 2009)
  6. ^ NPR Media, Letter of W.J. Howard, Assistant to the Secretary of Defense (Atomic Energy), to the Chairman of the Joint Committee on Atomic Energy, Congress of the United States (22 April 1966). (PDF) Page 1, Page2.
  7. ^ The Nuclear Information Project, History of the Strategic Air Command 1 January 1958 - 30 June 1958. Released under FOIA. (PDF)
  8. ^ Johnsville News Blogspot, H-Bomb lost in 1958 found off Georgia Coast? (16 Sept 2004)
  9. ^ America's Lost H Bomb, Discovery's Science Channel documentary about the Tybee Bomb (2007)
  10. ^ Chatham County Public Works and Park Services, Drinking Water Quality Consumer Confidence Report (2007)

References[edit]

External links[edit]

* [http://www.bbc.co.uk/programmes/b00l55xm BBC.co.uk], BBC audio programme on the Tybee Bomb, streaming audio<--->