Cold War

The Lost H-Bomb

The day the USAF accidentally dropped a hydrogen bomb on Spain – in January 1966, a USAF B-52 was involved in a mid-air collision with a KC-135 tanker and caused a terrible accident. Although there was no nuclear explosion, the radioactive contamination caused by this incident continues to the present day to impact the region around the small fishing village of Palomares, the people who live there and those who were involved in the clean-up operation that followed.

This is the incredible but true story of one of the forgotten incidents of the Cold War, the day the US Air Force nuked Spain.


The Airborne Alert Program

For much of the 1960s, US preparations for a possible attack by the Soviet Union involved keeping up to 12 B-52 bombers armed with live nuclear weapons in the air at all times. The aircraft involved in the Airborne Alert Program flew a number of pre-determined routes that kept them out of the airspace of the Soviet Union and the countries of the Warsaw Pact, but close enough that they could launch an immediate attack if required.

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To make the program as effective as possible, the B-52s had to remain in the air for as long as possible. This involved mid-air refuelling in a number of locations, a major logistics exercise that was maintained 24 hours a day, 365 days a year. It was only in the late 1960s, as new and more powerful US ICBMs were deployed, that this program was finally scaled-down.

airplane, b52, plane, jet, jet engines
B-52s often fly missions over Europe.

Some of the routes used kept the aircraft close to North America, flying from the east coast of the US, north over Newfoundland and Greenland before crossing to Alaska and then back to bases on the US west coast. The southern patrol area was different, involving nuclear-armed B-52s taking off from bases in the US before crossing the Atlantic, refuelling over Spain and then circling over the Mediterranean before returning to base.

To facilitate the southern route, in 1953, the US concluded the Pact of Madrid, a controversial agreement that allowed the creation of three USAF airbases and other military facilities in Spain in exchange for economic aid to the Franco regime. The main purpose of these airbases was to provide a location from which USAF KC-135 tankers could operate to refuel B-52s flying the southern route of the Airborne Alert Program.

Sunday/Monday, January 16th/17th 1966

On Sunday 16th January 1966, a USAF B-52G bomber of the SAC 51st Bomber Squadron took off from Johnson Air Force Base at Goldsboro in North Carolina. The bomber, callsign Tea 16,  was part of the Airborne Alert Program and was armed with four 1.5-megaton Mark 28 hydrogen bombs. It was scheduled to fly the southern route, refuelling over Spain before circling over the Mediterranean and then refuelling over Spain again before returning to base.

Boom operators view of a B-52.
Boom operator’s view of a B-52.

The outbound flight, refuelling and patrol over the Mediterranean were uneventful. On the morning of Monday 17th January, the B-52 headed for Spain to refuel before setting out to re-cross the Atlantic.

At around 10.30 it rendezvoused over the southern coast of Spain at around 30,000 feet with a KC-135 tanker operating from the USAF air base at Morón, near Seville. The weather was good and the crews of both the tanker and the bomber were very experienced but on this occasion, something went horribly wrong.

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The B-52 seemed to approach the tanker too fast and the refuelling boom struck the bomber’s fuselage, leading to the port wing being torn off.

The air to air refuelling was a routine operation. This accident caused the bomb to drop.
The air-to-air refuelling was a routine operation.

The fire quickly spread up the boom to the tanker, which crashed, killing all four members of its crew. Four of the seven-man crew of the B-52 were able to escape from the doomed aircraft as it descended rapidly and broke up, but the other three died when the bomber crashed onto the southern coast of Spain.


The village of Palomares is located on the south coast of Andalusia, around 5km from the town of Mojácar. In 1966, the south coast of Spain wasn’t yet a major tourist destination and Palomares was simply a poor fishing village – few of its 2,000 inhabitants lived in homes with electricity or running water. Villagers often watched as USAF aircraft refuelled high overhead, and a few reported actually seeing the collision on 17th January.

They watched in horror as the wreckage of both aircraft plunged to the ground in and around Palomares. Incredibly, no one on the ground was injured, but the four nuclear bombs from the B-52’s bomb bay had been ejected as it fell to Earth.

One landed in the village, one on hills close by and two fell into the sea. Ironically, the bodies of all seven dead USAF aircrew were found in or close to Palomares cemetery.

The B-52 wreckage.
Wreckage of the B-52G. Photo credit – Kit Talbot New York Times.

The hydrogen bombs had not been armed at the time of the collision, so there was no nuclear detonation (if there had been, much of southern Spain would still be a radioactive wasteland) but the detonators of both bombs that fell on land exploded, scattering around 3kg of radioactive plutonium dust across the town and the surrounding area.

Within minutes of the crash, SAC headquarters at Offutt Air Force Base in Nebraska were informed that there was a “Broken Arrow” incident in Spain (Broken Arrow was the USAF code used to denote missing nuclear weapons).

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Within one week, more than 500 USAF and Spanish personnel had set up camp in Palomares, checking for radiation and, most importantly, looking for nuclear weapons.

Two were quickly located on the ground in Palomares. Although the detonators were relatively small, each had created a crater fifteen feet wide and six feet deep and fragments of bomb casing were found up to one mile from where they impacted. A third bomb was found within 24 hours, washed up on a beach not far from Palomares. Its detonator had not exploded and it was quickly defused and removed. However, that still left one bomb unaccounted for.

The Search for the Missing H-bomb

The missing nuclear weapon was a major source of concern for the USAF, mainly because no one knew what might have happened to it. One theory was that it might have disintegrated at high altitudes, potentially scattering radioactive plutonium into the atmosphere. Another was that, if its parachute had failed, it might have descended at such high speed that it could have buried itself deep in the sandy soil around Palomares. The third theory was that it had landed in the sea.

When it became known that this accident had involved nuclear weapons, it attracted intense, and at times almost hysterical press coverage in Spain and around the world. In particular, many people found it incomprehensible (and terrifying) that it was possible to lose a nuclear weapon.

On land, US personnel located at the newly created Camp Wilson, just outside Palomares and next to the tail section of the crashed B-52, conducted fingertip searches over an area of more than six square miles in the hope of finding the missing bomb.

The terrain around Palomares included a number of deep wells and abandoned mine workings, and these too had to be carefully examined. At sea, a fleet of 34 US Navy ships took part in a search for the missing bomb, but it wasn’t until March 16th, two months after the accident that a deep-ocean research submersible operated by the US Navy, the DSV Alvin, located an object on the sea floor off Palomares that might be the missing bomb.

The ALVIN submersible was sent to look for the bomb.
The ALVIN submersible.

However, this object was in water over 2,000 feet deep, well beyond the depth at which divers can operate, and even worse, it was precariously balanced on the edge of an undersea canyon that was almost 4,000 feet deep.

If the bomb slipped into this canyon, it would be almost impossible to retrieve. After some tense and dangerous deep-water operations, two recovery lines were attached to the object and on April 7th, 1966, 81 days after the accident, it was winched on board the USS Petrel, a US Navy submarine rescue ship. It was the missing Mark 28 hydrogen bomb. The world heaved a collective sigh of relief, but the work in Palomares was far from over.

The H-bomb incident.
One of the recovered H-bombs.

The Clean-up Operation

Although there had been no nuclear explosion when the two bombs fell close to Palomares, a great deal of plutonium dust had been scattered in the area when the two of the bomb’s detonators exploded.

Scientists on-site recorded readings of 2 million alpha radiation emission counts per minute (CPM in the immediate vicinity of the bomb craters (though it was noted that this was simply the maximum level that could be recorded using the available equipment and that the actual figure may have been much higher). Up to two miles for the craters, readings of 7,000 CPM were recorded.

The problem was, this was the first time that an inhabited area had been contaminated with plutonium and no one had any idea of what a safe level was.

An area of 65 acres in and around Palomares was marked out with red flags as being unsafe. At first, the US government offered to maintain a presence on the site to ensure that it remained uninhabited until radiation levels fell to acceptable levels. But then someone pointed out that plutonium has a half-life of 25,000 years, which would have required a US presence in southern Andalusia for around 100,000 years! 

The bomb caused an awful lot of damage and expense.
Huge amounts of radiated soil were dug up and sent back to the US.

Instead, it was agreed that US and Spanish troops would remove contaminated topsoil which would be transported to America for disposal. From 11th – 17th March, these troops used shovels to collect contaminated soil in almost 5,000, 50-gallon oil drums.

These were transferred to the USNS Boyce and taken to the Atomic Energy Commission’s Savannah River disposal facility in South Carolina where they were buried with other low-level nuclear waste.

The search and clean-up operation was marred by another tragic aviation accident in February when a US Military Airlift Command C-124 heading for Palomares crashed near the city of Granada, killing all eight crew on board.  

Since 1966, the area around Palomares has been the subject of continuing and intense scrutiny – this is still the only inhabited area of the world to be contaminated with plutonium. As recently as the late 1990s, elevated levels of plutonium were reported at the mouth of a dry river bed near Palomares and in marine algae off the town’s beaches and in 2008, two trenches were discovered that had been filled with contaminated topsoil and were still producing high levels of radiation.


After the Palomares accident, B-52s of the Airborne Alert Program stopped refuelling over Spain. Two years later, the program was abandoned completely in favour of nuclear ICBMs. This wasn’t the only “Broken Arrow” incident involving nuclear-armed USAF B-52s. In two separate accidents in 1961, four nuclear bombs were dropped on California and North Carolina, though none detonated or caused large-scale contamination.

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In 1962, a B-52 carrying nuclear weapons collided with a KC-135 tanker over Kentucky and two bombs were released. Both were recovered without major contamination. The Palomares incident was the only occasion on which US nuclear weapons were accidentally dropped on another country.

The Cold War is now a distant memory and we no longer have to worry about bombers flying overhead carrying nuclear warheads. In the 1970s Palomares, like many other coastal areas in southern Spain, attempted to reinvent itself as a tourist destination with attractive and clean beaches.

That effort was hampered by the fact that parts of the village are still fenced off and classed as prohibited areas due to continuing high levels of plutonium contamination.

It has been estimated that anything up to .5kg of plutonium dust remains in the area and up to 50,000 cubic meters of topsoil may still be contaminated. In 2015 it was agreed with the US Obama administration that more Spanish radioactive topsoil would be taken to America for disposal. However, the subsequent Trump administration refused to honour this agreement.

No one knows what the long-term health effects are for the people who live in the region or for those involved in the clean-up operation. When removing over one thousand tons of contaminated topsoil, US personnel were protected only by the kind of dust masks that became so familiar during the recent COVID pandemic, but these are almost completely ineffective in preventing the ingestion of plutonium dust.

In 2021, a Federal suit was filed on behalf of US veterans exposed to plutonium during the Palomares clean-up. A number have contracted cancers in the years since, and many blame this on their exposure to radioactive contamination in 1966. At the time of writing, this class action is continuing.

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