A U.S. B-52 carrying four thermonuclear bombs broke apart over Spain, scattering plutonium and prompting lasting remediation efforts and policy changes.
Key Facts
- Date
- 17 January 1966
- Deaths (total)
- 7 (4 KC-135 crew, 3 B-52 crew)
- Nuclear bombs involved
- 4 B28FI thermonuclear bombs
- Contaminated area
- Approximately 2 km²
- Radioactive soil removed
- Approximately 1,750 tons
- Seabed search duration
- 80 days to recover fourth bomb
By the Numbers
Location
Cause → Event → Consequence
A U.S. Air Force B-52G, flying as part of Operation Chrome Dome's continuous nuclear-armed airborne alert patrols, attempted a mid-air refueling rendezvous with a KC-135 tanker at 31,000 feet over the Mediterranean Sea near Almería, Spain on 17 January 1966. The two aircraft collided during the refueling procedure.
The collision destroyed the KC-135, killing all four of its crew members, and caused the B-52G to break apart, killing three of its seven crew members. The bomber's four thermonuclear bombs were released; three fell on land near Palomares, with conventional explosives in two detonating and dispersing plutonium over roughly 2 square kilometers. The fourth bomb sank into the Mediterranean and was recovered intact after an 80-day search.
U.S. and Spanish authorities removed approximately 1,750 tons of contaminated soil for disposal in the United States. Spain banned U.S. nuclear-armed overflights of its territory. The incident, alongside a 1968 crash in Thule, Greenland, contributed to the termination of Operation Chrome Dome. Residual contamination persisted, resulting in a 2015 bilateral remediation agreement, with cleanup still incomplete as of 2025.