1961 Goldsboro B-52 crash

Crash of US Air Force bomber with nuclear warheads August 2026 October 2019 File:Goldsboro bomb Weapon No 1 color.jpg One of the Mk 39 nuclear weapons at Goldsboro, largely intact, with its parachute still attached 24 January 1961 Structural failure Accident Faro, Nahunta Township, Wayne County, 12 mi km north of Goldsboro, North Carolina 35 29 37 N 77 51 30 W region:US-NC_type:event inline,title An air-to-air left underside view of the 92nd Bombardment Wing's new camouflaged B-52G Stratofortress aircraft DF-ST-85-12450.jpg A Boeing B-52 Stratofortress similar to the one involved B-52G Strategic Air Command, United States Air Force 58-0187 8 Seymour Johnson Air Force Base Seymour Johnson Air Force Base 3 5 The 1961 Goldsboro B-52 crash was an aviation accident that occurred near Goldsboro, North Carolina, United States, on 24January 1961. A Boeing B-52 Stratofortress carrying two 3.8-megaton Mark39 nuclear bombs broke up in mid-air, dropping its nuclear payload in the process. Five crewmen successfully ejected or bailed out of the aircraft and landed safely; another ejected, but did not survive the landing, and two of them were killed in the crash.Sedgwick 2008 The accident is one of the most famous "Broken Arrow" nuclear accidents of the Cold War. Both of the weapons began their firing sequences upon separation from the aircraft, despite safeguards meant to prevent that from occurring. One of its nuclear bombs was judged by nuclear weapons engineers at the time to have been only one safety switch away from detonation, and that it was "credible" to imagine conditions under which it could have detonated. The other bomb did not get as far into its firing sequence, but became deeply embedded in a muddy field, and one of its major weapons components (the thermonuclear "secondary" stage) was regarded as irrecoverably lost after an extensive, failed effort to recover it.20 September 2013 Goldsboro revisited: account of hydrogen bomb near-disaster over North Carolina – declassified document https://www.documentcloud.org/documents/796426-goldsboro-revisited-pp-1-2-copy.html#document/p2 21 June 2020 Guardian NewsNew Declassifications on Nuclear Weapons Safety and Security https://nsarchive.gwu.edu/briefing-book/nuclear-vault/2022-11-18/new-declassifications-nuclear-weapons-safety-and-security National Security Archive 18 November 2022 Burr William Accident USA North Carolina 305 North Carolina USA North Carolina W N 35 29 24 77 51 0 Accident scene top USA North Carolina W N 35 20 22 77 57 38 Seymour Johnson AFB bottom The aircraft, a B-52G, was based at Seymour Johnson Air Force Base in Goldsboro, and part of the Strategic Air Command's airborne alert mission known as "Cover All" (a predecessor to Operation Chrome Dome), which involved a continuous flow of staggered, nuclear-armed bombers on a "ladder" route into the Canadian Arctic and back.Defense Atomic Support Agency 1966 36–37. "Accident #3" on page 36 of the report is clearly (despite redactions) the Goldsboro accident, and associates it with a "Project Coverall operation."An internal SAC history for 1961 noted that, "From a modest beginning in September 1958, with one bomb wing launching a combat ready B-52 every six hours, SAC's airborne alert indoctrination program had increased to 11 wings launching a total of 12 sorties per day by late 1962." The "Cover All" (as the internal SAC documents refer to it) operation doubled the previous number of sorties, bringing it up to 12 per day, flying on a "ladder" route "resembling giant north-south loops stretching from the US north into the Canadian Arctic", and began on 15January 1961. Problems emerged in this arrangement, however, as simply adding more flights to the same route would make it crowded and "jeopardize flight safety," and if the flights climbed to 1/16th of the total force it would constitute a "safety hazard." As a result, a new "bomber stream airborne alert concept known as 'Chrome Dome'", which used two routes (one circumnavigating Canada, the other on a route from the Atlantic and Mediterranean), was developed. While it was pending approval, three other airborne alert "indoctrination training" operations were implemented after "Cover All" ended on 31March 1961: "Clear Road" (1April–30June), "Keen Axe" (1July–30September), and "Wire Brush" (1October–5November). "Chrome Dome" began on 6November.1962 History of Strategic Air Command July–December 1961 (Historical Study no. 88, Volume I) https://www.scribd.com/document/57194878/Strategic-Air-Command-History-1961 79–82History of Headquarters Strategic Air Command 1961 (SAC Historical Study no. 89) 1962 60–61, 180–181 https://oscarzero.files.wordpress.com/2013/02/excerpts-from-hq-sacs-history1961.pdf Around midnight on 23–24January 1961, the bomber had a rendezvous with a tanker for aerial refueling. During the hook-up, the tanker crew advised the B-52 aircraft commander, Major Walter Scott Tulloch, that his B-52 had a fuel leak in the right wing. The refueling was aborted, and ground control was notified of the problem. The B-52 was directed to assume a holding pattern off the coast until the majority of fuel was consumed. However, when it reached its assigned position, the pilot reported that the leak had worsened and that 37000 lbs kg of fuel had been lost in three minutes. The aircraft was immediately directed to return and land at Seymour Johnson Air Force Base.Bickelman 1961 3 As the aircraft descended through 10000 ft m on its approach to the airfield, the pilots were no longer able to keep it in stable descent, and "lost all control as the B-52 went into a gyration best described as a spin."Speer 1961 p. 2 (PDF p. 83) The pilot in command ordered the crew to abandon the aircraft, which they did at 9000 ft m. Five men landed safely after ejecting or bailing out through a hatch, one did not survive his parachute landing, and two died in the crash.Sedgwick 2008Bickelman 1961 3 The third pilot of the bomber, Lt. Adam Mattocks, is the only person known to have successfully bailed out of the top hatch of a B-52 without an ejection seat.Yancy 1961 The crew's final view of the aircraft was in an intact state with its payload of two Mark39 thermonuclear bombs still on board, each with yields of 3.8 megatons.Following an early account of the accident by Ralph Lapp in 1962, many sources over the years the claim that the bombs at Goldsboro had yields of 24 megatons. This is now known to not be true. Lapp or his source may have gotten the weapons involved in the accident confused with the 23–25 megaton B41 nuclear bomb. (Lapp's account also incorrectly states there was a single bomb involved in the accident.) The exact weapon models involved in the accident were classified for many years, as were most details of the accident, leading to many seemingly contradictory accounts.Lapp Ralph Kill and Overkill: The Strategy of Annihilation Basic Books 1992 127 Sometime between the crew ejecting and the aircraft crashing, the two bombs separated from the aircraft.Bickelman 1961 3 The unmanned aircraft broke up in the air shortly after the crew ejected. Witnesses reported seeing two flashes of red light, suggesting that fuel explosions contributed to the breakup of the plane. At 12:35 a.m. EST on January24, the remaining pieces of the B-52 impacted with the ground. The aircraft wreckage covered a 2 mi2 km2 on in area of tobacco and cotton farmland at Faro, about 12 mi km north of Goldsboro. The arrangement of the aircraft pieces suggested that several pieces of the B-52 were upside down when they struck the ground.AF Form 14 Report of Aircraft Accident 24 January 1961Speer 1961 p. 2 (PDF p. 83) Explosive ordnance disposal (EOD) teams from Seymour Johnson and other bases arrived on the scene quickly, disarming the one bomb that was easily accessible. Representatives from the Albuquerque Operations Office of the U.S. Atomic Energy Commission were alerted to the accident on the morning of January24. A team of scientists and engineers from the AEC, Sandia National Laboratories, and Los Alamos National Laboratory assembled at Kirtland Air Force Base in New Mexico. They were joined by representatives from the Department of Defense Nuclear Safety Research Directorate. They flew to Seymour Johnson AFB on a C-47 cargo plane, arriving at approximately 10:15 p.m. EST on the night of January24.Bickelman 1961 3 Weapons Mark 39 Mod 2 nuclear bombs right|thumb|A basic diagram of a Teller-Ulam design thermonuclear weapon. Of note are the "primary" (labeled "A") and the "secondary" (labeled "B") subcomponents. The Mark39 Mod2 likely had a very similar basic arrangement, along with a firing set (X-Unit) for injecting gas into the core of the "primary" and detonating it. thumb|Diagram of the external features of a Mark39 nuclear bomb, with the warhead compartment labeled as "A" and the parachute pack labeled as "B". The location of the access panel for the Arm/Safe Switch is indicated at the rear of the bomb, before the parachute pack. On the top of the parachute pack is the compartment from which the arming rods would be withdrawn. On the nose would be written: "REJECT IF DENTED OR DEFORMED". thumb|The "normal trajectory sequence" for the use of a Mark39 Mod2 nuclear bomb, indicating the arming sequence under normal (non-accident) nuclear weapons use conditions. thumb|An image of the MC-772 Arm/Safe Switch of the same kind used in the Mk39 Mod2 nuclear bombs involved in the 1961 Goldsboro accident. The two bombs involved in the Goldsboro accident were Mark39 Mod2 thermonuclear weapons with a maximum predicted yield of 3.8megatons of TNT equivalent. It was a multi-stage thermonuclear weapon with a "primary" and a "secondary" stage. In such weapons, the "primary" is a mostly-fission driven stage whose energy is used to compress the "secondary," which initiates further fission reactions, nuclear fusion reactions, and the neutrons generated by the fusion stage can in turn generate more fission reactions. In the case of the Mark39 Mod2, the "primary" was also boosted, meaning that at the moment of detonation a gaseous mix of deuterium and tritium was injected into its core, which would generate fusion reactions at the moment of detonation, producing neutrons that would increase the efficiency of the "primary". The pit of the primary was entirely composed of enriched uranium ("all-oralloy"), with no plutonium, and had a sealed-pit, meaning that it was fully-assembled at all times.By contrast, the Mark39 Mod0, a previous version of the same weapon, did not have a sealed pit. Its pit was kept outside of the primary, required being inserted using an "in-flight insertion" mechanism activated by the crew in order for the weapon to have any possibility of a nuclear yield. The "secondary" also contained enriched uranium in its "sparkplug." The Mark39 Mod2 warhead was itself enclosed in a gravity bomb casing which had a compartment containing a drogue parachute that both allowed the aircraft dropping it to move to a safe distance, and allowed it to be detonated on the surface by a contact fuze without risk of the weapon breaking on contact with the ground. The weight of the assembled bomb was between 9000 and 10000 lb kg.Hansen Chuck Swords of Armageddon, version 2 Chukela Publications 2007 V 14, 354–359 Immediately after the Goldsboro accident, technicians from Sandia National Laboratories, the national laboratory which had the primary responsibility of nuclear warhead safety engineering, subjected the recovered weapons to careful analysis to determine how close they were to a possible nuclear detonation. Various accounts of their conclusions have circulated over the years, with some emphasizing the closeness of the detonation, and some emphasizing the success of the various safety features of the nuclear warheads. To make sense of their analysis and the controversies, it is first necessary to understand what the normal firing sequence of a Mark39 Mod2 used in combat conditions would be. The Mark39 bombs would be suspended in the two bomb bays of the B-52 plane carrying it, one in front of the other. "Arming rods" were extended out of each weapon, and held in place with "safing pins." Prior to normal use, the "safing pins" would need to be pulled out of the bomb horizontally, which could be done by the crew in the cockpit by means of a lanyard that was connected to them. Additionally, prior to dropping the bomb, the pilot would need to operate a switch inside the cockpit (the T-380 Readiness Switch), which would enable the navigator to power-on and "arm" another switch (the T-249 Aircraft Monitor and Control Unit). The latter would operate the MC-772 Arm/Safe Switch inside the Mark39 bomb itself.de Montmollin Hoagland 1961 5Bickelman 1961 8 The Arm/Safe Switch was a low-voltage, solenoid-operated electro-mechanical switch that was kept in the "Safe" position until a deliberate choice was made to cause a nuclear detonation, but could be switched from "Safe" to "Arm" by a 28-volt electrical signal.de Montmollin Hoagland 1961 6Sandia National Laboratories 2010 at 24:30: "And that one safety device was the pre-arming switch which was operated normally by a 28-volt signal."Sandia National Laboratories 1968 18 The Mark39 Mod2 could only be detonated as a "contact" burst (and not an airburst).Carpenter C.L. https://www.osti.gov/opennet/detail?osti-id=16340715 18 February 1960 Expedited Procedures in Designing and Producing a Major MOD Kit Sandia National Lab (DOE OpenNet) The bomb bay had a solenoid-operated lock system which would deploy the parachute automatically upon release if operated, as opposed to a free-fall release. Once the bomb cleared the bomb bay and the arming rods were retracted, they would trigger the MC-845 Bisch generator they were connected to. This was a single-pulse generator that began the overall firing sequence. The Bisch generator would send an initiation signal to the MC-640 low-voltage thermal battery pack, as well as the MC-543 Timer. The timer would begin to count down. The retraction of the arming rods would also close valves sealing a reference chamber in the MC-832 Differential Pressure Switch, a barometric fuze for detecting the bomb's altitude.de Montmollin Hoagland 1961 6 After the weapon had fallen a required vertical distance, the differential pressure switch would close contacts which passed battery current through the MC-772 Arm/Safe Switch and from there to the MC-788 High Voltage Safing System, which is armed by continual current being applied to it.de Montmollin Hoagland 1961 8–9 Upon receiving this current, the MC-788 would then connect the (not yet-charged) high-voltage thermal battery to the X-Unit, the electrical device that provides a high voltage signal to the detonators used in the "primary" stage of the weapon.The MC-788 High Voltage Safing System was a switch that "would prevent high voltage from reaching the X-unit so that if a fire or extreme heat ignited the high-voltage batteries, no harm would result." It was not, in other words, an independent Arm/Safe switch separate from the MC-772; the MC-722 would pass the 28-volt signal of the low-voltage batteries to the MC-788, which would close its connections and allow the high-voltage batteries to pass their 2,500-volt signal to the X-Unit. "When the bomb fell a distance to provide sufficient differential pressure to close the differential-pressure-switch contacts, the circuit was completed through the arming/safing switch [MC-722] to the energizing coils of the safing rotary switch [MC-788]. This latter switch then moved to the armed position, the ground was removed from the X-unit, and the circuit from the high-voltage thermal battery pack to the X-unit was completed."Sandia National Laboratories 1968 11, 18 Another more general explanation of this system is in a later review of safety innovations at Sandia at this time: "Motor-driven safing switches incorporated into bombs, called 'ready-safe' switches, were operated by the pilot moving a control knob in the cockpit. Switches capable of holding off in excess of 2,500volts were required for those systems... which had incorporated high voltage, thermally activated batteries. Systems which used low voltage power sources and some type of voltage step-up technique could use low voltage switches for the safing switch. Both high and low voltage safing switches had motor-driven contacts that would close when a 28-volt signal was applied."Brodie 1987 10 After the timing circuit completed its countdown of 42 seconds, it would then deliver initiation power to the MC-641 High Voltage Thermal Battery pack. This would begin to generate its full voltage of 2,500volts within one to two seconds, which would be applied directly to the trigger circuit and, through the MC-788 High Voltage Safing System, to the capacitor bank of the X-Unit. Once the bomb impacted the ground, a crush switch on the nose of the bomb (the MC-787 Trigger Circuit) would be closed and trigger the X-Unit to discharge its capacitors and initiate the high-explosive system in the "primary" stage of the weapon.de Montmollin Hoagland 1961 6Sandia National Laboratories 1968 18–19 At some point in the above sequence, not indicated in declassified documents (possibly because of its classified nature), "squibs" on the Los Alamos Laboratory 1A Valve Mechanism would fire and cause the gas from the boost reservoir to be injected into the "primary" of the bomb.de Montmollin Hoagland 1961 6The ordering of events in some of the documents seems to indicate that the triggering of the boost gas would have been done by a line which was enabled by the arming of the MC-722 Arm/Safe switch. For example, the table included in Speer's observer report, which is ordered to show "subsequent progress of the fusing/firing sequence," notes the status of the tritium reservoirs after the status of the Arm/Safe Switch, and before the status of the High Voltage Thermal Battery (triggered by the timer).Speer 1961 p. i (PDF p. 81) Neither of the weapons at Goldsboro had their tritium reservoir "squibs" actuated, despite Weapon No.1's timer having run down and successfully triggered its High Voltage Thermal Battery. This occasioned no obvious comment in the post-mortem accounts, suggesting this was as expected, which would be the case if the tritium reservoirs were only dischargeable if the Arm/Safe switch was set to "arm". By the time of the Goldsboro accident, the MC-772 Arm/Safe switch had been replaced in some Mark39 Mod2 units with another switch, the MC-1288 Arm/Safe switch, which also restricted the charging of the low-voltage thermal battery if the switch was in the "Safe" position. This was done to ensure additional safety for the weapons, and would remove the need for safing pins in the pullout rods. This modification (designated as Alt197) had been approved in January 1960, but had not been performed on either of the bombs involved in the Goldsboro accident.de Montmollin Hoagland 1961 9yuba197 In another B-52 crash a few weeks later, in Yuba City, California, the weapons involved did have Alt197 applied to them, but the low-voltage thermal batteries were nonetheless activated in one of the weapons despite the MC-1288 Arm/Safe switches being in the "Safe" position. According to the Defense Atomic Support Agency, "post-mortem analysis indicates a probable cause of the activation of the low voltage thermal batteries of the one weapon was a cable short which permitted the energy from the MC-845 Bisch Generator to bypass the MC-1288 Arm/Safe Switch. It is suspected that the MC-845 pulse resulted from the mechanical shock sustained upon impact and was passed to the MC-640 [thermal batteries] through one of the possible random short circuits."Defense Atomic Support Agency 1966 41 For a parachute delivery, the Mark39 would need to be released between 3500 ft and 5700 ft above the target. For a free-fall delivery, it would need to be released at least 35000 ft above the target, or else it would hit the ground prior to the timer circuit completing its countdown and the X-Unit being charged.Sandia National Laboratories 1968 19 The two Mark39 Mod2 nuclear bombs involved in the Goldsboro crash had distinctly different outcomes. Official reports identified them as weapon no.1 (or bomb no.1) and weapon no.2 (or bomb no.2), with the first's parachute having deployed and the second having crashed into the ground in free-fall without any decrease in its speed. Weapon no.2 was kept in the forward bomb bay of the aircraft, while weapon no.1 was in the aft bomb bay.Speer 1961 p. 1 (PDF p. 82) Weapon No. 1: Serial No. 434909 (parachute) thumb|Weapon No.1 as it was discovered by the EOD team after the accident. thumb|The "probable trajectory sequence" of Weapon No.1 in the Goldsboro Accident. Weapon no.1, identified as serial number 434909 (and kept in the aft bomb bay), was flung out of the aircraft at an altitude of around 9000 ft above the ground. It apparently twisted from its rack in a way that caused the "safing pins" on its arming rods to pull out longitudinally and without any sign of damage, despite not having been pulled from the crew compartment. Once it left its rack, the bomb dropped in such a way that its arming rods were pulled out in much the same manner as an intentional drop sequence would be. This caused its MC-845 Bisch generator to be actuated, initiating the MC-640 low-voltage thermal battery pack and the MC-543 timer. The explosive actuators triggered the deployment of the bomb's parachute as in normal functioning.Speer 1961 p. 2 (PDF p. 83)de Montmollin Hoagland 1961 5 The MC-832 Differential Pressure Switch operated as normal, and passed the battery current to the MC-772 Arm/Safe switch. This switch was found by the initial explosive ordnance disposal (EOD) team on the scene to be in the "Safe" position,The Man Who Disabled Two Hydrogen Bombs Dropped in North Carolina https://storycorps.org/stories/the-man-who-disabled-two-hydrogen-bombs-dropped-in-north-carolina/ 2020-11-08 storycorps.org and did not pass its current on further. The MC-543 safe-separation timer ran its full length (42 seconds), and initiated the MC-641 High-Voltage Thermal Battery Pack. Upon impact with the ground, the crush-switch closed, which would under normal circumstances fire the weapon. But as the MC-772 Arm/Safe Switch had not activated the MC-788 High-Voltage Safing Switch, the X-Unit was not charged, and no detonation occurred. The "squibs" that would inject the boost gas into the weapon were not released and the tritium reservoir was found intact.de Montmollin Hoagland 1961 10 The bomb was found in an upright position, with its parachute hanging on adjacent trees, about 1 mile in behind where the main wreckage of the aircraft crashed.Bickelman 1961 5 On January24, the EOD team from Wright-Patterson Air Force Base disassembled and "safed" the weapon (by disconnecting the tritium reservoir from the primary), and returned it to Seymour Johnson AFB. The weapon was described as having only sustained "negligible damage", with only a broken nose plate, and its nose buried about 18 in in the soil. Approximately one pint (half a liter) of JP-4 jet fuel was found in the bomb case.Speer 1961 p. 3 (PDF p. 84) There have been differing interpretations offered as to how close this particular weapon was to having a nuclear detonation. An initial report by Sandia in February 1961 concluded that weapon no.1 "underwent a normal release sequence in which the parachute opened and the components of the weapon which were given an opportunity to actuate by the pulling of the Bisch rods did behave in the manner expected. Full operation of this weapon was prevented by the MC-772 Arm/Safe Switch, the primary safing device."Bickelman 1961 8 Other measures meant to provide additional safing, such as the "safing pins," failed. Parker F. Jones, a supervisor at Sandia, concluded in a reassessment of the accident in 1969 that "one simple, dynamo-technology, low voltage switch stood between the United States and a major catastrophe" He further suggested that it would be "credible" to imagine that in the process of such an accident, an electrical short could cause the Arm/Safe Switch to switch into the "Arm" mode, which, had it happened during the Goldsboro accident, could have resulted in a multi-megaton detonation.Jones 1969 2: "If a short to an 'arm' line occurred in a mid-air breakup, a postulate that seems credible, the Mk39 Mod2 could have given a nuclear blast" A Sandia study on the US nuclear weapons safety program by R.N. Brodie written in 1987 noted that the ready/safe switches of the sort used in this era of weapon design, which required only a 28-volt direct current to operate, had been observed many times to inadvertently be set to "arm" when a stray current was applied to the system. "Since any 28-volt DC source could cause the motor to run, how could one argue that in severe environments 28voltsDC would never be applied to that wire, which might be tens of feet long?" He concluded that "if [weapon no.1] in the Goldsboro accident had experienced inadvertent operation of its ready-safe switch prior to breakup of the aircraft, a nuclear detonation would have resulted."Brodie 1987 15–16 Bill Stevens, a nuclear weapon safety engineer at Sandia, gave the following assessment in an internal documentary film produced by Sandia in 2010: "Some people can say, 'hey, the bomb worked exactly like designed.' Others can say, 'all but one switch operated, and that one switch prevented the nuclear detonation.Sandia National Laboratories 2010 at 24:38 Charlie Burks, another nuclear weapons systems engineer for Sandia, also added: "Unfortunately, there have been thirty-some incidents where the ready/safe switch was operated inadvertently. We're fortunate that the weapons involved at Goldsboro were not suffering from that same malady."Sandia National Laboratories 2010 at 24:51 Weapon No. 2: Serial No. 359943 (free-fall) thumb|The "probable trajectory sequence" of Weapon No.2 in the Goldsboro Accident. thumb|upright=1.3|EOD personnel work to recover the buried Mk. 39 thermonuclear bomb that fell into a Faro, North Carolina, field in 1961. thumb|upright=1.3|right|Air Force personnel working in an underground pit to recover parts of the MK-39 nuclear bomb thumb|The battered MC-722 Arm/Safe Switch from Weapon No.2 in the Goldsboro B-52 accident, 1961. Weapon no.2 (kept in the forward bomb bay) separated from the B-52 later than weapon no.1, when it was between 5000 ft and 2000 ft above the ground. It was discovered about 500 yards away from the crew compartment and wing sections of the aircraft wreckage, along the line of flight.Bickelman 1961 5 As with weapon no.1, its "safing pins" were pulled, allowing its arming rods to withdraw. As before, this initiated the MC-845 Bisch generator, which activated the low-voltage thermal batteries and started the MC-543 Timer. However, because the weapon had been released at such a low altitude, and its parachute had failed to open, it collided with the ground at high speed. Its timer circuit had run only 12 to 15 seconds when it impacted, and consequently, the high-voltage thermal battery did not activate. For unknown reasons, its parachute did not deploy, despite the parachute deployment mechanism having been activated.Bickelman 1961 6de Montmollin Hoagland 1961 11, 14–15 As the impact of the weapon had resulted in a crater of significant size – 5 ft in deep and 9 ft in in diameter – it was initially assumed that the high-explosives in the weapon's "primary" stage had detonated. However, it was later confirmed that there had not been any HE detonation of this or the other weapon, and there had been no contamination of the site with fissile material.Bickelman 1961 1, 3–4 The EOD team found that the bomb had apparently left the airplane still attached to its rack, and that its timer circuit could not start until it had left its rack. (The rack was found a mile east of the bomb itself.) The bomb had become deeply buried in mud, and it required three days of excavation to recover its MC-772 Arm/Safe Switch. In 2013, Lt. Jack ReVelle, an EOD officer on the scene, recalled the moment: "Until my death I will never forget hearing my sergeant say, 'Lieutenant, we found the arm/safe switch.' And I said, 'Great.' He said, 'Not great. It's on arm.Tuttle 2013 Another EOD officer recalled: "The arm safety switch was on, armed and functioning."Atchison 2017 A representative of the Atomic Energy Commission noted that after the discovery of the Arm/Safe Switch in the "Armed" position, and the arming rods having been pulled out, he and his colleagues "wondered why bomb No.2 had been a dud." An immediate analysis showed that the Arm/Safe Switch was "electrically... neither in armed nor safe position."Speer 1961 pp. 5–6 (PDF pp. 86–87) The switch and other components were shipped to Sandia for further "post-mortem" analysis, and it was determined that while the switch's indicator drum had rotated to the "Arm" position, it had disconnected from its contacts, and was never electrically "armed." They concluded that this was damage caused by the impact shock of the bomb hitting the ground, which also damaged the switch to such an extent that the circuit could not have closed even if it were in the "Arm" position.Speer 1961 p. 3 (PDF p. 84)Bickelman 1961 6de Montmollin Hoagland 1961 4 As with weapon no.1, the tritium reservoir in weapon no.2 was recovered intact and without any loss of tritium. The MC-788 High Voltage Safety Switch was destroyed on impact.Speer 1961 p. i (PDF p. 81) Weapon no.2 had broken into pieces on its impact, and the EOD technicians spent several days attempting to recover its pieces from the deep mud. The "primary" of the weapon was recovered on January30, six days after the accident, at a depth of some 20 ft in the mud. Its high-explosives had not detonated, and some had crumbled out of the warhead sphere. By February16, the excavation had gotten down to 70 ft, and had not located the "secondary" component of the weapon.Speer 1961 p. 4 (PDF p. 85) Excavation of the second bomb was complicated by the freezing cold, a high water table, and the extreme muddiness. Pumps were used to remove water, and the sides of the crater were reinforced with plywood, but it was decided after digging down to 42 ft to abandon the effort. The fusion "secondary" of the second weapon was never recovered.Department of Defense/Department of Energy 1996 PDF p. 389) The University of North Carolina at Chapel Hill subsequently determined the buried depth of the secondary component to be 180 ± 10 ft m 0.Hardy 2005 September 2013 An analysis by Sandia in February 1961 concluded that: Weapon No. 2, which underwent something other than normal release from the aircraft, evidenced by the fact that the parachute did not deploy, also had its arming rods extracted, and those components which were given the opportunity to act, did act in the manner expected. Full operation of this weapon was prevented by several things: Impact occurred so soon after separation of the Bisch rods that the timers were not given an opportunity to run down. The Arm/Safe Switch was in the "Safe" condition as the weapon left the aircraft.Bickelman 1961 8 Another analysis by Sandia engineers in 1961 concluded that while in both weapons the MC-772 Arm/Safe Switch operated "as it was designed to do," the lanyard-controlled safing-pins "cannot be relied upon to prevent initiation of the fuzing sequence" in this kind of accident, and recommended implementing a modification to the weapons "as rapidly as possible" that would prevent the fuze power supply from activating except when live release was intended.de Montmollin Hoagland 1961 19 A 1969 analysis by Sandia supervisor Parker F. Jones concluded that the Goldsboro accident illustrated that "the Mk39 Mod2 bomb did not possess adequate safety for the airborne alert role in the B-52."Jones 1969 2 Summary table The "Official Observer's Report" of the accident summarized the condition of the two weapons' firing systems with the following table:Speer 1961 p. i (PDF p. 81) + Table of Component Behavior, Fusing and Firing Systems Part No. Component Bomb #434909 [No. 1] Bomb #359943 [No. 2] Arming Wires [Arming/Pullout rods] Pulled Pulled MC-845 Pulse Generator [Bisch generator] Actuated Actuated MC-834 Explosive Actuator [started timer] Fired Fired MC-543 Timer Run down (42 sec.) Run (12-15 sec.) MC-832 Differential Pressure Switch [barometric altitude fuze] All contacts closed 2 contacts closed MC-640 Low Voltage Thermal Battery Actuated Actuated MC-772 Arm-Safe Switch Safe Safe [but visually appeared to look armed] 1-AAnother document lists the "Reservoir type" of the weapons involved in this accident as "2A-12" and "2A-22755".Weapon Systems Accidents 1 January 1964 https://www.osti.gov/opennet/detail?osti-id=16137645 Mound Laboratory DOE OpenNet Tritium Reservoir Full [i.e. unfired] Full [i.e. unfired] MC-641 High Voltage Thermal Battery Actuated Not actuated MC-788 Rotary Safing Switch [High-Voltage Safing System] Not operated Destroyed MC-730 X-Unit [Primary firing set] Not charged Not charged MC-616 Nose crystals [Contact fuze] Crushed Crushed To summarize the Sandia post-mortem described in detail above, for Bomb No.1, had the Arm-Safe Switch been set to "Arm," or malfunctioned in a way that enabled the firing circuit to act as if it was armed, the bomb would have detonated with a full nuclear yield upon the contact fuze closing when it hit the ground. For Bomb No.2, because its timer had not run out by the time it struck the ground, it could not have detonated even if its Arm-Safe Switch had been set to "Arm", as its thermal batteries had not charged, and they would be needed to fire the weapon. Legacy The Goldsboro accident was reported in national and international newspapers by the next day, described as a plane crash with "two unarmed nuclear weapons" which, at time of reporting, posed "no immediate danger" from a nuclear detonation, but that "a danger from non-nuclear high explosives" required all people to keep the site clear.United Press International Atomic Bomb Plane Falls 24 January 1961 Chicago Daily Tribune 1 An article in Time in March further specified that the weapons involved were "H-bombs."SAC's Deadly Dozen Time 17 March 1961 https://content.time.com/time/subscriber/printout/0,8816,894429,00.html This news coverage caused a SAC representative to be asked about the accident, and other accidents from 1959 onward, at a hearing of the United States Congress that March, which were officially and publicly disclosed for likely the first time. Despite this, an official SAC history from 1988 reported, erroneously, that "until 1966, the history of SAC's alert operation had been without incident." Political scientist Scott Sagan has used this as an example of "what appears to be the complete disappearance of a number of B-52 airborne alert accidents from the command's organizational memory" and indicative of "the depth of SAC's reluctance to acknowledge such problems."Sagan Scott D. The limits of safety: Organizations, accident, and nuclear weapons Princeton University Press 1993 202 Secretary of Defense Robert S. McNamara, in a Top Secret January 1963 meeting with representatives from the Departments of Defense and State, as well as the White House, used the Goldsboro accident to argue against the delegation of authority to use nuclear weapons to SACEUR, citing the possibility of accidental nuclear war. According to declassified meeting notes, McNamara "went on to describe crashes of US aircraft, one in North Carolina and one in TexasMcNamara's reference to a Texas "Broken Arrow" may refer to the November 4, 1958, an accident in which a B-47 with a Mark39 Mod1 (sealed pit) weapon on board crashed and exploded shortly after takeoff (for a training mission) from Dyess Air Force Base, near Abilene, Texas. The high-explosives in the weapon's primary detonated, dispersing depleted uranium, highly enriched uranium, and lead. The US Air Force has released no information about other "Broken Arrow" incidents with sealed-pit weapons taking place in Texas prior to 1963.Non-Time Critical Removal Actions Uranium and Lead Contaminated Soil Report, B-47 Crash Site, Abilene, TX December 2011 Sullivan – Arrowhead Federal Services JV https://www.dyess.af.mil/Portals/145/Docs/Environment/B-47%20Crash%20Site.pdf?ver=2016-11-04-144031-197, where, by the slightest margin of chance, literally the failure of two wires to cross, a nuclear explosion was averted. He concluded that despite our best efforts, the possibility of an accidental nuclear explosion still existed."https://www.documentcloud.org/documents/799655-mcnamara.html#document/p2/a122657 Memorandum of Conversation: State-Defense Meeting of Group I, II, and IV Papers 26 January 1963 National Security Archive Consequences to Mark 39 bomb design A safety modification to Mark39 Mod2 weapons known as Alt197 had been approved in January 1960, but not yet applied to all deployed weapons prior to the Goldsboro accident, and was not applied to the weapons involved in the accident. Alt197 replaced the MC-772 Arm/Safe switch with the MC-1288 Arm/Safe switch, with the main change being that the latter would prevent the charging of the low-voltage thermal battery when the Arm/Safe switch was in the "Safe" position, and as such would make sure that no electrical current was available anywhere within the bomb to power additional switches or hardware, legitimately or not.de Montmollin Hoagland 1961 9 After the accident, all other Mark39 Mod2 weapons without the modification were taken off of deployment status ("red-lined") until the modification could be applied to the remaining inventory of the weapons.Stevens William L. The Origins and Evolution of S2C at Sandia National Laboratories (SAND99-1308) September 2001 https://nsarchive.gwu.edu/document/29457-document-2-william-l-stevens-origins-and-evolution-s2c-sandia-national-laboratories Sandia National Laboratories (via the National Security Archive) 54yuba197 Consequences to B-52 design Wet wings with integral fuel tanks considerably increased the fuel capacity of B-52G and H models, but were found to be experiencing 60% more stress during flight than did the wings of older models. Wings and other areas susceptible to fatigue were modified in 1964 under Boeing engineering change proposal ECP 1050. This was followed by a fuselage skin and longeron replacement (ECP 1185) in 1966, and the B-52 Stability Augmentation and Flight Control program (ECP 1195) in 1967.Knaack 1988 276–277 Easement thumb|The farm field with the easement, including the nearby circular patch of trees in the middle of the farm field In 1962, the landowner was paid $1,000 to grant the United States of America a perpetual 200 ft on radius circular easement over the remains of the buried second bomb.Deed Book 581, Wayne County (NC) Courthouse 1962 89–91http://www.ibiblio.org/bomb/ease.html Davis Family Easement 18 November 2000 Ibiblio.org 12 September 2014 The site of the easement, at 35 29 37 N 77 51 30 W inline US-NC_type:event, is visible as a disturbed area, and lies approximately 250 ft north of an obvious circle of trees (and disused cemetery) in the middle of a plowed field visible on Google Earth. The terms of the easement: ... convey unto the Grantee, the United States of America and its assigns, a perpetual and assignable easement for the establishment, maintenance and operation of a restricted area in, upon, over and across the land described herein, consisting of: <li>The right to prohibit said land from being used in any manner other than for the growing of crops, the growing of timber, or as pasture. Such permitted uses shall be subject to the following conditions: No drilling, digging, boring, excavating or other disturbances of the land will be permitted below a depth of five (5) feet. No structures of any kind whatsoever, except normal farm fencing, shall be constructed or erected upon said land. The right to traverse said lands on foot for the purpose of making periodic inspections. The right to cross other lands of the grantor on foot and by reasonable routes, to gain access to the easement area for the purpose of exercising the rights herein set forth. Road marker thumb|Road marker in Eureka, NC, commemorating the 1961 B-52 crash. In July 2012, the State of North Carolina erected a historical road marker in the town of Eureka, 3 miles North of the crash site, commemorating the crash under the title "Nuclear Mishap".Shaffer 2012 See also 1961 Yuba City B-52 crash (another B-52/Mk39 Mod2 accident, weeks after Goldsboro) 1964 Savage Mountain B-52 crash (another B-52 nuclear crash, with a different bomb type) Special Weapons Emergency Separation System List of military nuclear accidents RAF Lakenheath nuclear weapons accidents – involved another US military nuclear accident 8 days before the Goldsboro crash United States military nuclear incident terminology#Broken Arrow Notes Citations 30em General and cited references Bickelman H.D. February 1961 Accident Report on B-52G Near Seymour Johnson Air Force Base North Carolina (SCDR 106-61) Sandia Corporation (via the National Security Archive at George Washington University) https://nsarchive.gwu.edu/document/29459-document-4-h-d-bickelman-sandia-corporation-accident-report-b52g-near-seymour Brodie R. N. A Review of the U.S. Nuclear Weapons Safety Program – 1945 to 1986 (SAND86-2955) Sandia National Laboratories February 1987 https://www.osti.gov/opennet/servlets/purl/1116535.pdf de Montmollin J. M. Hoagland W. R. February 1961 Analysis of the Safety Aspects of the MK 39 MOD 2 Bombs Involved in B52G Crash Near Greensboro, North Carolina (SCDR 81-61) Sandia Corporation (via the National Security Archive at George Washington University) https://nsarchive.gwu.edu/document/29458-document-3-j-m-de-montmollin-and-w-r-hoagland-sandia-corporation-analysis-safety https://www.pbs.org/wgbh/americanexperience/media/filer_public/24/db/24dbd8c1-c74a-4841-ab63-c3258a14ceb4/_cc_afswp_technical_incidents_reduced1.pdf Accidents and Incidents Involving Nuclear Weapons (DASA Technical Letter 20-3) Defense Atomic Support Agency PBS 1 March 1966 Department of Defense/Department of Energy 1996 Narrative Summary of Accidents Involving U.S. Nuclear Weapons, 1950-1996 https://www.governmentattic.org/40docs/NNSApost1980BrokenArrow_2021.pdf U.S. Department of Energy (via Government Attic) (report begins on page 359 of the PDF) Jones Parker F. 22 October 1969 Goldsboro Revisited: Or How I Learned to Mistrust the H-Bomb: Or to Set the Record Straight Sandia Corporation https://www.documentcloud.org/documents/796426-goldsboro-revisited-pp-1-2-copy.html Sandia National Laboratories January 1968 History of the MK 39 weapon (SC-M-67-671/RS 3434/20) https://osf.io/g8hmf Sandia National Laboratories Always/Never: The Quest for Safety, Control, and Survivability – Part 2 YouTube https://www.youtube.com/watch?v=sb2qo5m_hTY 2010 Speer Ross B. Official Observer's Report, Air Force Accident, Goldsboro, North Carolina https://www.governmentattic.org/40docs/NNSApost1980BrokenArrow_2021.pdf February 28, 1961 US Atomic Energy Commission (via Government Attic) (report begins on page 81 of the PDF) https://www.annistonstar.com/the_st_clair_times/lincoln-resident-helped-disarm-hydrogen-bomb-following-b-52-crash-in-north-carolina-56-years/article_eea2f00c-5eb1-11e7-83bc-0fdff9df2dcb.html Lincoln resident helped disarm hydrogen bomb following B-52 crash in North Carolina 56 years ago The Anniston Star David Atchison July 2, 2017 https://books.google.com/books?id=tOYDAAAAMBAJ The Pentagon's Broken Arrows Gary Hanauer Mother Jones Magazine 28 13 July 2009 April 1981 Hardy Scott The Broken Arrow of Camelot: An Analysis of the 1961 B-52 Crash and Loss of the Nuclear Weapon in Faro, North Carolina 2005 East Carolina University https://librarycatalog.ecu.edu/catalog/1090178 Knaack Marcelle Size Post-World War II Bombers, 1945–1973 http://www.afhso.af.mil/shared/media/document/AFD-100526-026.pdf 1988 Office of Air Force History Washington, DC 978-0160022609 25 September 2013 27 November 2011 https://web.archive.org/web/20111127170631/http://www.afhso.af.mil/shared/media/document/AFD-100526-026.pdf dead Pilkington Ed US nearly detonated atomic bomb over North Carolina – secret document The Guardian 20 September 2013 https://www.theguardian.com/world/2013/sep/20/usaf-atomic-bomb-north-carolina-1961 20 September 2013 Jessica Sedgwick Bombs Over Goldsboro This Month in North Carolina History http://www.lib.unc.edu/ncc/ref/nchistory/jan2008/index.html 24 January 2012 January 2008 https://web.archive.org/web/20111228001711/http://www.lib.unc.edu/ncc/ref/nchistory/jan2008/index.html 28 December 2011 dead http://www.ocregister.com/articles/bomb-381837-revelle-nuclear.html Sharon Keith When two nukes crashed, he got the call (Part 2 of 2) Orange County Register (California) 27 December 2012 21 September 2013 Later, diggers found the ARM/SAFE switch. It was in the ARM position. Why that bomb didn't explode has been debated for years. Was the ARM/SAFE switch broken? Did the impact of the crash spread out the parts so far they couldn't affect each other? Was the bomb a dud? No one will ever know. Shaffer Josh Shaffer: In Eureka, They've Found a Way to Mark 'Nuclear Mishap.' 2 July 2012 http://www.newsobserver.com/2012/07/02/2173231/shaffer-in-eureka-they-have-found.html 2 July 2012 News and Observer 4 July 2012 https://web.archive.org/web/20120704205249/http://www.newsobserver.com/2012/07/02/2173231/shaffer-in-eureka-they-have-found.html dead Tuttle Steve A Close Call – Hero of 'The Goldsboro Broken Arrow' speaks at ECU East Carolina University https://news.ecu.edu/2013/03/27/a-close-call/ 24 January 2022 27 March 2013 Yancy N. Life-Death Story of Flight Told Greensboro News & Record 26 January 1961 Further reading Dobson Joel 2011 The Goldsboro Broken Arrow https://books.google.com/books?id=rR3jygAACAAJ Lulu Press (self published) 978-1257869527 Yenne Bill 2012 B-52 Stratofortress: The Complete History of the World's Longest Serving and Best Known Bomber https://books.google.com/books?id=s-ENnos_1oIC&pg=PA55 Zenith Imprint 978-1610586726 External links C-SPAN Video book Goldsboro Brokenarrow Account of hydrogen bomb near-disaster over North Carolina – declassified document—The Guardian US plane in 1961 'nuclear bomb near-miss'—BBC News Last Week Tonight with John Oliver (HBO) show from 2014-07-27 describing the incident The Night Hydrogen Bombs Fell over North Carolina Simulation illustrating the fallout and blast radius had the bomb actually exploded Audio interview with response team leader New Details on the 1961 Goldsboro Nuclear Accident https://nsarchive2.gwu.edu/nukevault/ebb475/ nsarchive2.gwu.edu National Security Archive, The George Washington University 11 January 2022 9 June 2014 Category:1961 in military history Category:1961 in North Carolina Category:Aviation accidents and incidents involving the Boeing B-52 Stratofortress Category:Aviation accidents and incidents in North Carolina Category:Aviation accidents and incidents in the United States in 1961 Category:Aviation accidents and incidents involving nuclear weapons Category:January 1961 in the United States Category:Nuclear accidents and incidents in the United States Category:Nuclear weapon safety Category:Wayne County, North Carolina