A B-52G on a Strategic Air Command air warning mission was refueling over the Atlantic when the tanker crew told its commander that it had a fuel leak on its right wing. The tanker drove away. The bomber carried two Mk 39 Mod 2 thermonuclear weapons and fell near Seymour Johnson Air Force Base at approximately midnight on January 24, 1961. What happened between those two times is set out in two Sandia Corporation reports written the following month. One of them had been made public only in a heavily redacted form and the other had not been made public until 2021, when both were released through a Freedom of Information Act request by Government Attic. The National Security Archive published them the following year. Read together, they are a contemporary engineering account of the night, and they are stranger and more specific than the story that emerged from them. The leak on the right wing The pilot reported the leak to Seymour Johnson, said he had full control of the plane and asked for instructions. They told him to stay over the ocean and burn excess fuel. As he did that, the hole in the wing apparently turned into a major tear. HD Bickelman, the Sandia representative who flew to the crash site, recorded in his accident report that the plane was reported to have lost 37,000 pounds of fuel in a two-minute period. The commander still had the plane. They took it over the ground to perform a stabilization run, the standard check at about 10,000 feet that the commander still has control of the plane. During that run he lost control and the aircraft apparently lost a wing or part of it. The crew’s account during the rescue The rescue order went out. Five of the eight men on board made it out alive and three died. The wreckage fell along the flight path for approximately one and a half kilometers, the tail section one kilometer from the wing and the crew compartment, which were found inverted, badly burned and completely demolished. Bickelman recorded the assumption that the rupture occurred in the vicinity of 9,000 feet. The surviving crew told investigators that both guns were still on board when they left and that all switches were in the normal safe position. Under airborne warning rules of the time, the bomb rack lock had to be locked with a safety seal, the aircraft’s T-249 monitor and control units and its T-380 readiness switch had to be sealed in the off position, and safety pins had to be installed on the weapons’ extraction rods. The T-249 units were in the navigator compartment, which burned. Parts of them were found, but their condition at the time could not be determined, and Bickelman only recorded that the condition of the weapons made it logical to assume that they had been safe. Weapon number one in the sandy clay The bomb in the aft bomb bay fell under a parachute that deployed normally. He struck almost vertically against sandy clay, buried his nose about eighteen inches into the ground, stayed upright, and was found with his parachute hanging from the trees beside him. It was intact with only minor damage and its components could be analyzed on site. The component list is the part that matters. The safety pins on the reinforcing rods had been removed and the rods themselves had been removed. The low voltage thermal battery had tripped. The stopwatch had completed its cycle. The barometric trajectory activation switch showed all its contacts closed. The high-voltage thermal battery, which would have charged the trip capacitor, had tripped. The crush switch in the nose was deformed, and the report by JM de Montmollin and WR Hoagland says that it can be assumed that it provided a signal fire at the time of impact. Two switches had not been moved and they were the two that mattered, in that order. The safety switch on the MC-772 arm was in the safe position, which is what prevented current from reaching the high voltage safety switch behind it, so that switch also remained safe and the trip capacitor never charged. De Montmollin and Hoagland expressed it in a single line: under these conditions, the MC-772 and the MC-788 prevent the assembly of the weapon. Bickelman’s own note about the gun is evasive. The appearance, he wrote, is that ripping the aircraft removed the safety pins from the cocking rods, and that from that point on the weapon went through a normal sequence of events in which detonation was prevented because the arm safety switch was in the safe position. The tank valve had not tripped and the tritium remained where it was. An explosive ordnance disposal team made the bomb safe by pinching and cutting the fill tube between the reservoir and the well, then dismantling the weapon. The crater left by gun number two The bomb in the forward bomb bay fell without its parachute, which is a bit of a mystery in itself: Strategic Air Command later told investigators that the deployment mechanism, explosive devices and timers had worked, and the reason the cover never opened was unknown. The weapon broke loose, passed the plane’s point of impact, and left a hole five feet deep and approximately nine feet wide. The first assumption at the scene was that the high explosive had suffered what reports called a point detonation and had opened the crater. It wasn’t like that. Excavation was slowed by surface water in the hole, and the primary was not recovered until the end of the month, from a depth of about six metres. The recovery of this weapon produced the only alarming-looking evidence in both reports. When the arm safety switch was pulled from the rubble, its indicator drum read ARM. There was no arming. Inside the case, the plastic wafers carrying the fixed contacts had broken off their posts and moved about a quarter of an inch, and there was no continuity across the switch in either position. The engineers concluded that the rotation of the drum was undoubtedly due to the impact, that the contacts in all likelihood never closed in the arm position, and that the switch should be considered safe until the moment of impact. The Sandia Bank autopsy also found that this weapon’s timer had elapsed about twelve seconds before impact damage stopped it, well short of the forty-two seconds in which its contacts would have closed, so its high-voltage battery never activated at all. The famous line was written eight years later. The line most people know about Goldsboro does not come from any of these reports. It comes from a 1969 review of Sandia by Parker F. Jones, who oversaw the lab’s nuclear weapons safety department, and which The Guardian published in 2013 after a Freedom of Information Act disclosure to writer Eric Schlosser. The National Security Archive, pointing readers to that review, says the two 1961 documents confirm a later assessment by Sandia that a main control switch, set to the safe position, was the only thing standing in the way. The 1961 documents describe the same mechanism in flatter language. Bickelman’s summary states flatly that there were no detonations, that no radiological safety hazards occurred, and that the safety features of both bombs performed normally. De Montmollin and Hoagland conclude that the safety switch prevented a nuclear detonation in these weapons, as designed. Engineers were describing a system working, not a coin falling in the right direction. Both reports also come with their printed limits. Tickets are eliminated. The cover of Montmollin’s report itself names the wrong city, placing the accident near Greensboro instead of near Seymour Johnson, which is where the first sentence of its introduction places it. The two reports also place the weapon in free fall at different heights as it moves away from the plane, although the ranges overlap. De Montmollin and Hoagland say it probably spread between 2,000 and 5,000 feet. Bickelman places it at between 2,000 and 3,000 feet back from the twelve seconds the stopwatch ran, and adds that the speed and position of the gun at that time are subject to some speculation. None of the reports, as published, show returns; The National Security File describes the weapons as being four megatons each. And the line that carries the most weight in the entire file, the one about the nose providing a signal fire, is written as an assumption rather than a measurement. The modification requested by the report The recommendation at the end of the Montmollin report is not rhetorical. It requests that a specific modification, ALT 197, approved in January 1960, be incorporated as quickly as possible into each bomb of the Mk 15/39 family used in aerial alert. ALT 197 replaces the MC-772 with a different arm safety switch and places the new switch’s contacts on the line between the arming generator and the low-voltage thermal battery matches, so that a safely fired weapon cannot initiate its own power source. With that change made, the report says, the system was deemed safe enough for alert flights without safety pins installed on the extraction rods. The treatment at the moment when Bickelman’s report turns, towards its end, towards something else. The Air Force immediately released the details, as far as was known at the time, and the area’s evening newspapers published them that same Tuesday along with a statement that the weapons were safe and that there were no radiological dangers, and after a day of human interest monitoring the story was dismissed as no longer news. He considered the handling to be very competent, and by 1961 standards it was: the weapons were not concealed. What remained out of public view was the list of components and the order in which they were fired. The public was informed about the accident before it ended later that day. He waited sixty years for these reports to explain at the component level how the sequence developed. About this articleThis article is for general information and reflection. It is not professional advice. For your specific situation, consult a qualified professional.
