Investigation Summary
The accident occurred while the USS Ticonderoga was en route from Subic Bay, Philippines, to Yokosuka, Japan. A training exercise known as a 'crew cut', a nuclear weapon loading exercise, was authorized by Captain Robert Miller to practice the handling of live ordnance. Despite being a drill, the aircraft was loaded with a live B43 thermonuclear weapon with a Y1 yield (one megaton). At the time of the incident, the carrier was approximately 68 miles (109 km) from Kikai Island, Kagoshima Prefecture, Japan. After the weapon was secured to the Skyhawk's belly, the pilot boarded the aircraft to participate in the movement exercise. As plane handlers, known as blue shirts, were manually pushing the aircraft from Hangar Bay No. 2 onto the No. 2 elevator, the aircraft continued to roll backwards, went over the side of the carrier, and plunged into the ocean. The weight of the aircraft and the heavy nuclear store caused it to sink rapidly. Search efforts were unsuccessful due to the extreme depth of the water, estimated at 16,000 feet (4,900 meters). The U.S. government initially reported the incident occurred in the open sea to avoid diplomatic friction with Japan, as the carrier was within 100 miles of Japanese territory at the time.
Final Conclusions
The loss was attributed to human error during the manual handling of the aircraft on the hangar deck. The failure to stop the aircraft's rearward momentum as it was positioned on the elevator resulted in it rolling off the carrier's edge. The incident remains one of the most significant 'Broken Arrow' cases due to the permanent loss of a high-yield thermonuclear weapon in international waters near Japan.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
B43 Nuclear Bomb
A variable-yield thermonuclear weapon; the specific unit lost was a Y1 variant with a 1-megaton yield.
No. 2 Aircraft Elevator
The platform used to move aircraft between the hangar deck and the flight deck, from which the aircraft rolled off.
Interesting Facts
- 01The B43 nuclear bomb involved had a yield of one megaton.
- 02The incident occurred approximately 68 miles from Kikai Island, Kagoshima Prefecture, Japan.
- 03The U.S. Department of Defense did not publicly reveal the location and details of the incident until 1989.
- 04The aircraft belonged to Attack Squadron 56 (VA-56), part of Carrier Air Wing Five.
- 05The depth of the water at the site of the loss is approximately 4,900 meters (16,000 feet).
Safety Actions & Advisories
Nuclear Weapons Handling Procedures
The incident led to stricter oversight of 'crew cut' exercises and the handling of live nuclear ordnance during non-combat transit, particularly regarding the manual movement of loaded aircraft on carrier decks.
Known Controversies & Unanswered Questions
Number of Weapons Involved
Reference ↗While most official records and eyewitness accounts specify a single B43 bomb, a document from Los Alamos National Laboratory suggested two weapons may have been involved.
Location Disclosure
Reference ↗The U.S. government initially claimed the incident happened 500 miles from land. The 1989 revelation that it occurred within 70 miles of Japanese territory caused a diplomatic dispute with Japan regarding their 'Three Non-Nuclear Principles.'