54 years ago, a Boeing B-52G Stratofortress, carrying four B28 nuclear bombs, took-off from Seymour Johnson air base in North Carolina for the scheduled flight to the Soviet Union border and back, being a part of Operation Chrome Dome (airborne alert missions flown between 1960 and 1968, keeping the nuclear bombers ready to perform rapid strike on USSR territory, if needed).
The flight plan was to fly over the Atlantic Ocean, Mediterranean Sea to the European border of the Soviet Union and then returning home. This flight required two mid-air refuellings and the second of them started at 1030 hrs on 17th January, at 31,000 feet, close to the Spanish coast.
The B-52 approached the KC-135 at too high speed and started to overrun the tanker. Both aircraft collided, fuelling nozzle hit the B-52 fuselage and caused an explosion. KC-135 was completely destroyed, killing all four crew members. The bomber broke apart, killing three crew members – four survivors managed to parachute safely.
Three nuclear bombs were then found near Palomares village in Almeria, Spain – their non-nuclear load detonated at the impact, resulting in contamination of approximately 2 square kilometres. The fourth bomb was missing, and it was found later in the Mediterranean Sea after an extensive search operation lasting more than two months.