The Time We Accidentally Nuked New Mexico
If you ever think that you’re having a bad day, remember that the US military once dropped their biggest hydrogen bomb by accident — on United States soil.
On May 22, 1957, the crew of a B-36 Peacemaker was given the important mission of transporting a Mark 17 hydrogen bomb from Texas to a base in Albuquerque, New Mexico. The Mark 17 was the largest thermonuclear weapon ever put into service by the United States. It was a whale of a bomb, 24 and a half feet long, with an estimated explosive yield more than six hundred times the size of the device that leveled Hiroshima. Where the original atomic bombs had incinerated everything within a mile radius, the Mark 17’s reach was closer to ten miles. Colloquially referred to as a “city killer,” it was arguably the most powerful weapon in the known universe.
Like most nuclear devices of the time, the Mark 17 was doubly secured in the bomb bay, first with a primary pneumatic system and then by a manually-inserted backup locking pin. The bomb could only be dropped if the pneumatic system were set to release and the locking pin were removed.
There was just one problem: in case of emergency, crews needed to be able to jettison their volatile cargo. To accommodate this possibility, standard procedure mandated the removal of the locking pin for takeoff and landing. At the start and end of each flight, a member of the crew would have to climb up to where the bomb hung from its restraints and slide out the pin.
In the case of the 1957 incident, the unlucky crewmember was the plane’s navigator, First Lieutenant Bob Carp. As the B-36 descended to 1,700 feet, he clambered into the bomb bay and dangled himself over the massive Mark 17, removing the locking pin.
It’s unclear how the primary release system became disengaged. According to the initial reports, as the plane hit turbulence, Carp lost his balance and reached out for something to steady himself. This something allegedly turned out to be the lever for the bomb’s release system. Carp, on the other hand, insists that the lever caught on his equipment and shifted as he worked his way along the length of the bomb.
However it happened, without the locking pin to hold it in place, the 21-ton payload promptly fell out of the plane, taking the bomb bay doors with it.
A few things happened in quick succession. Freed of forty-six thousand pounds of cargo, the plane lurched skyward, gaining more than a thousand feet of altitude in seconds. A befuddled crewmember near the plane’s tail reflexively shouted “Bombs away!” Carp, meanwhile, came barreling out of the bomb bay exclaiming “I didn’t touch anything! I didn’t touch anything!” The B-36’s radio operator sent a frantic distress call to base, telling the horrified tower operator, “We dropped a hydrogen bomb!”
The crew watched haplessly as the most powerful weapon in the known universe plummeted to Earth.
Directly below, oblivious to the unfortunate scene unfolding in the sky, a cow was grazing on a plot of land owned by the University of New Mexico. A second later, the Mark 17 hydrogen bomb detonated, distributing shell fragments, bovine remains, and Albuquerque scrubland evenly over a mile-wide radius.
The good news? Although the weapon detonated, it wasn’t fully armed. In order to go nuclear, bombshells like the Mark 17 required a certain amount of radioactive material (plutonium in this case) to be compressed into a specific volume. To crush the plutonium together, the outer layer of the bomb was made of conventional (non-nuclear) explosives. The bomb’s impact in the cow pasture set off this outer layer, resulting in a large but decidedly less-apocalyptic blast. In fact, the weapon and its plutonium core were always stored separately during flights, to avoid this exact situation.
The B-36 and her crew were met with “quite a group of VIPs” upon their arrival at nearby Kirtland Air Force Base. Military officials descended on the bomb site, collecting scraps of top-secret artillery and sweeping the mesa with geiger counters. They found that the impact crater, a 25-foot-wide scar, was mildly radioactive. The contaminated soil was excavated, and the airmen were sworn to secrecy.
The Mark 17 incident is not our only instance of nearly-averted nuclear winter. According to declassified documents, the U.S. military spent the latter half of the twentieth century fumbling nuclear bombs like a fourth-string quarterback. In March 1958, for instance, a B-47 Stratojet crew accidentally dropped a Mark 6 atomic bomb (twice the size of the original Little Boy) on South Carolina. The plane’s bombardier, sent to find the source of a warning light, had unintentionally pulled out the bomb’s locking pin. The bomb’s conventional payload detonated in a local family’s backyard, obliterating their daughters’ playhouse and wounding six people.
On another occasion, after a B-52 broke apart over Goldsboro, North Carolina, it jettisoned its cargo—two nuclear weapons, complete with their radioactive cores. The first bomb landed safely, albeit after undergoing six of its seven detonation stages (Robert MacNamara wrote in a memo that “literally the failure of two wires to cross” prevented an explosion 250 times the blast in Hiroshima). The second bomb’s parachute failed to deploy, and the weapon slammed into a nearby farm, falling to pieces. The military collected as many of the fragments as it could, but the bomb’s radioactive core was apparently never located.
The official term for an event where nuclear weapons are lost, accidentally deployed, or damaged is “broken arrow.” To date, the Pentagon has confirmed 32 broken arrows, although a recent document obtained by journalist Eric Schlosser lists hundreds more incidents of varying scope. Even without these additional examples, it’s clear that it took a little more luck to escape the Cold War era than we care to admit.
[Correction Note]: An earlier version of this article incorrectly labelled the aircraft involved in the Kirtland AFB incident as a B-26. This issue has since been corrected.
