One would certainly hope that we have always had a lock down on nuclear weapons, right?  After all, the most powerful nations in the world wield these destructive weapons.  However, the nature of these weapons wasn't exactly well understood on the birth of the technology.  That's evident enough in the use of tactical arms on the front lines, and the idea of keeping enemies at bay behind walls of radioactive fallout.  Meanwhile, we were selling tickets to atomic bomb tests in the middle of the Nevada desert.  Sound reasoning, no?  Unfortunately, it didn't stop there.  There were a number of incidents in the 1950s, 1960s, and even the 1970s that involved damage or even loss of atomic weapons.  The most notorious of these incidents is the Palomares Incident.

The aircraft involved was a B-52G Stratofortress, tail number 58-0256 on a flight route that was typical for the nuclear deterrent mission that was ongoing in the Mediterranean region.  Refueling of the aircraft was to take place near the coast of Spain en-route and on departure from the area.  As was typical of the mission, the B-52 crew was carrying four hydrogen bombs in the weapons bay.  The B-52 was set to refuel with a KC-135 Stratotanker.

Both aircraft are substantially large, and both remain in service today.  The B-52 was built specifically for the purpose of carrying heavy payloads long distances.  Payloads, such as hydrogen bombs, were particularly heavy and required a much larger weapons bay than could be offered by smaller aircraft.  The aircraft had the ability to travel large distance, but required multiple in-air refuelings in order to successfully complete a mission, thus the need for the KC-135.  The KC-135 was also a very large aircraft, with the dedicated mission of refueling aircraft in the air and eliminating the need for an aircraft to land to resupply.  Unfortunately, on the morning of 17 January 1966, these two planes would collide in mid-air during what should have been a routine refueling mission.

On the morning of 17 January 1966, the B-52G carrying tail-number 58-0256 overshot its approach to the KC-135 tanker.  A typical call to break away was not received by the B-52 crew, resulting in an impact.  The KC-135 was almost immediately engulfed in flames after fire ignited the fuel reserves in the aircraft.  The B-52 was damaged severely with it's left wing having been ripped off in an explosion, and control of the aircraft was lost, forcing the crew to eject.  Meanwhile, the four hydrogen bombs were still on board the aircraft.  The wreckage fell near the town of Palomares, Spain where three of the bombs also fell to earth.  In two of the three multi-stage bombs, the conventional warhead detonated.  This caused an explosion which spread radioactive material in the region.  All three of these were recovered shortly after the impact.

The fourth bomb was not immediately located, as it's parachute had deployed in freefall.  The wind currents that day suggested the bomb had drifted out to sea.  It was not until 2 April 1966 that the bomb was identified at a depth of about 3,000 feet that it was recovered.

All of the crew on board the KC-135 died moments after impact.  Three crew aboard the B-52 also died, while the other four were severely injured.  The accident was reported immediately by a second B-52 that was in the area, and the resulting response time was relatively short for this reason.  However, despite the rapid response, as of 2006, traces of contamination remain in the region of Palomares.  The incident remains one of the greatest operational blunders of the U.S. Air Force.