Investigation Summary
The aircraft, part of the Strategic Air Command's 'Cover All' airborne alert mission, encountered a fuel leak in the right wing during a mid-air refueling rendezvous over South Carolina. The crew attempted to return to Seymour Johnson Air Force Base, but as they descended through 10,000 feet, the pilots lost control as the aircraft entered a spin. The right wing suffered a major structural failure, and the aircraft broke apart at 8,000 feet. Five crew members successfully ejected or bailed out, while three perished. The two 3.8-megaton Mark 39 nuclear bombs were jettisoned during the breakup. Weapon No. 1 fell by parachute and was found upright in a forest. Weapon No. 2 fell free, impacting a muddy field at nearly the speed of sound. The impact caused the bomb to disintegrate, and while the high explosives did not detonate, the thermonuclear 'secondary' stage was never recovered, having buried itself deep in the water-logged soil. The Air Force eventually purchased a perpetual easement for the land to prevent any future excavation of the site.
Final Conclusions
The accident was caused by a major structural failure of the right wing following a massive fuel leak. The investigation highlighted distinct failure modes for the two weapons. In Weapon No. 1, seven out of eight arming steps were completed, and only a single manual 'ready-safe' switch prevented detonation. In Weapon No. 2, the Arm/Safe switch was found in the 'Armed' position by recovery teams; however, post-mortem analysis at Sandia revealed that the switch was in the 'Safe' condition as it left the aircraft. The impact shock had physically rotated the indicator drum to 'Armed' while simultaneously disconnecting it from its contacts, meaning it was never electrically armed. Nuclear weapons engineers later judged that the Mk39 Mod2 lacked adequate safety for airborne alert roles, as a simple short circuit could have bypassed the remaining safeguards.
Photographic Evidence (1)
Video Analysis
The Plane Crash That Almost Nuked America | 1961 Goldsboro B-52 Incident — A detailed look at the 1961 Goldsboro B-52 crash, where a structural failure led to the accidental release of two nuclear bombs over North Carolina.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Mark 39 Nuclear Bomb
A multi-megaton thermonuclear weapon designed to be delivered by B-52 bombers, featuring multiple arming and fusing safeguards.
MC-772 Ready-Safe Switch
The final manual safety switch that prevented the detonation of Weapon No. 1; it was the only one of eight safeguards that did not fail or activate during the accident.
Interesting Facts
- 01The aircraft was carrying two Mark 39 nuclear bombs, each with a yield of 3.8 megatons.
- 02One bomb completed seven of the eight steps required for detonation, including the deployment of its parachute and the activation of its firing sequence.
- 03The second bomb impacted the ground at approximately 700 mph and broke apart without a nuclear explosion.
- 04The thermonuclear secondary of the second bomb was never recovered and remains buried approximately 100 to 200 feet underground.
- 05The Air Force purchased a circular easement of 400 feet in diameter at the impact site of the second bomb to prevent disturbance of the remains.
Safety Actions & Advisories
Nuclear Safeguard Redesign
The incident led to the implementation of more robust safety switches and 'permissive action links' (PALs) to prevent accidental or unauthorized nuclear detonations.
Known Controversies & Unanswered Questions
Detonation Probability
Reference ↗While the government initially downplayed the danger, declassified 1963 reports by Parker F. Jones of Sandia National Laboratories stated that the bomb was 'one simple, low-voltage switch' away from a nuclear blast.