The Day We Lost the H-Bomb: Cold War, Hot Nukes, and the Worst Nuclear Weapons Disaster in History

More clues appeared. That first week, a searcher found a round metal plate with two sides squared off. Experts identified it as a tail closing plate — the part that fits on the end of a bomb and holds the parachutes in place. They also discovered that it had come from bomb number four — the first identifiable bit of the weapon that anyone had found. But the plate was found about a hundred yards from the B-52's tail section, an area that the Air Force had already searched exhaustively Surely it should have been seen earlier. Had someone put it there? For days, the Air Force asked around.

Finally they found the local man who had had originally discovered the tail plate. He had been away at his mother's funeral. He said he had seen the plate fall on the day of the accident, picked it up, and given it to a member of the Guardia Civil, who had dropped it near the tail section. New information in hand, the Air Force stepped up the search in an area closer to the shoreline and shipped the tail plate back to the United States for examination.

Only a handful of people in the United States knew the full significance of this particular piece of metal, and they worked in a jumble of drab government buildings at Sandia National Laboratories in Albuquerque, New Mexico. The engineers at Sandia didn't design nuclear warheads; that job belonged to the physicists at Los Alamos. However, they engineered just about every other part of America's nuclear bombs: the casing, the fusing mechanism, the arming and safing devices, and the parachutes. They knew the Mark 28 inside and out.

Sandia in the 1960s was a secret paradise for the slide rule set. Every engineer who worked there had graduated in the top of his or her college class. They had cutting-edge equipment, seemingly endless funding, and a fairly loose rein. They also worked with a deep sense of mission. Nuclear weapons, most of them believed, kept their country safe from the Soviets. Sandia engineers considered themselves to be not only the elite of Albuquerque but indispensable to the defense of the United States.

On this mission, Sandia's marching orders trickled down from the top. As soon as President Johnson heard news of the crash, he called Secretary of Defense Robert McNamara. He first asked McNamara if the bombs might explode. When McNamara assured him that they would not, the president told him to “do everything possible to find them.” Word was passed to Jack Howard, McNamara's assistant secretary of defense for atomic energy. A few days later, Howard dialed his friend Alan Pope, the director of Aero Projects at Sandia. He told Pope that bomb number four remained at large and asked for help in finding it. Right away, Pope called Randy Maydew, the manager of Sandia's Aerodynamics Department. Maydew put down the phone, scrambled into the office, and got to work.

High-energy and hyperactive, Maydew, like many engineers, was a man of compulsive habits. Every morning, he sweated through a half-hour regimen of floor exercises; every Saturday, he wrote in his journal; every Sunday, he attended church. He liked to move fast and get things done quickly, and when he got the call about Palomares, he headed straight to Sandia and gathered a small team. They sat down to crunch some numbers and see if they could pinpoint the location of the missing bomb, or at least make an educated guess. The engineers knew the altitude, heading, and speed of the planes at the time of collision and had their own data on the aerodynamics of the bomb. They also had a state-of-the-art supercomputer, the IBM 7090, at their disposal. But they weren't sure exactly where the accident had taken place and had only sketchy, conflicting meteorological data.

Furthermore, they didn't know if the bomb was intact or broken to bits or which, if any, of the bomb's parachutes had deployed.

The parachute question was critical. Stuffed into its back end, the Mark 28 carried a complicated multiparachute system that allowed pilots to drop nuclear bombs from a variety of altitudes. Pilots could, for instance, speed into enemy territory under the radar, drop bombs at an extremely low altitude — below 500 feet — and still clear out before the bomb exploded.

Sandia had developed this “laydown system” in the 1950s to help American planes evade Soviet air defenses, which had been specifically designed to shoot down small numbers of aircraft carrying nuclear weapons. According to intelligence experts, the Soviet defense missiles could hit planes flying as high as 60,000, maybe 80,000, feet. But the system could not hit very-low-flying planes, especially if they whizzed by faster than the speed of sound. However, a pilot dropping a nuclear bomb from a low altitude would surely be caught in the deadly blast — unless there was a way to delay the explosion. The Air Force called Sandia.