Investigation Summary
The incident occurred during Operation Snow Flurry, a simulated combat mission involving a flight from Georgia to the United Kingdom. During the initial climb-out shortly after takeoff, the co-pilot, Captain Charles Woodruff, attempted to engage the bomb harness locking pin, but a cockpit warning light indicated it had failed to seat. The navigator and bombardier, Captain Bruce Kulka, was sent to the bomb bay to manually seat the pin. Because the bomb bay was too narrow to accommodate a parachute, Kulka entered the unpressurized area without one. While searching for the locking pin mechanism in the dark, jostling bay, he mistakenly used the emergency release lever as a handhold. The 7,600-pound Mark 6 bomb fell onto the bomb bay doors, which gave way under the weight, casting the weapon out of the aircraft at 15,000 feet. Kulka narrowly avoided falling out of the open bay by grabbing onto internal structures. The bomb impacted the property of Walter Gregg, a railroad conductor and former paratrooper, detonating approximately 50 yards from his garage. The aircraft, registration 53-1876A, was operated by the 375th Bombardment Squadron of the 308th Bombardment Wing.
Final Conclusions
The accidental release was attributed to a combination of mechanical difficulty and human error. The locking pin had been problematic during ground loading, requiring a weapons supervisor to seat it with a hammer, yet the crew did not cycle the mechanism to ensure it was functional before takeoff. The subsequent manual intervention in flight led to the navigator accidentally pulling the emergency release. Following the incident, the Air Force implemented more secure fastening procedures for nuclear weapons to prevent accidental jettisoning. The Gregg family sued the Air Force and was awarded $54,000 in compensation.
Video Analysis
1958 Mars Bluff Nuclear Bomb Incident — A detailed historical account of the accidental dropping of a Mark 6 nuclear weapon on a South Carolina family's property by a B-47 Stratojet.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Mark 6 Nuclear Bomb
A 7,600-pound fission weapon developed from the Mark 3 'Fat Man' design, featuring a conventional high-explosive trigger used to compress a nuclear core.
Bomb Harness Locking Pin
A steel pin designed to prevent the weapon from falling if the electrical lock released; it was required to be disengaged during takeoff and landing for emergency jettison capability.
Emergency Release Mechanism
A pneumatically powered catch that allowed the crew to immediately jettison the weapon in the event of an emergency during takeoff or landing.
Interesting Facts
- 01The Mark 6 bomb contained approximately two tons of conventional high explosives.
- 02The nuclear capsule (fissile core) was not inside the bomb but was stored in a 'birdcage' container elsewhere on the aircraft.
- 03Six civilians, including Walter Gregg's wife and children, sustained non-life-threatening injuries.
- 04The explosion killed approximately one dozen hens belonging to the Gregg family.
- 05The Gregg family appeared on the TV show 'I've Got a Secret' three weeks after the incident.
- 06Air Force technicians determined radioactive contamination was low enough to be remediated by simple washing.
Safety Actions & Advisories
Weapon Fastening Security
The U.S. Air Force implemented more secure fastening methods for nuclear weapons aboard aircraft to prevent accidental or unintentional jettisoning.
Known Controversies & Unanswered Questions
Initial Reporting of Nuclear Accidents
Reference ↗At the time of the incident, The New York Times reported it was the first known instance of an atomic bomb being dropped in the U.S. outside of testing grounds. However, it was later revealed to be at least the 13th serious nuclear weapon accident, including a similar jettison incident in Georgia just weeks prior, highlighting a lack of public transparency regarding 'Broken Arrow' events.