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Incidents & Accidents

NOTE: The events outlined here involved operational weapons, nuclear materials, aircraft, and/or missiles under control of the U.S. Air Force, U.S. Navy, or the Atomic Energy Commission. The U.S. Army has never experienced an event classified as an accident involving nuclear weapons. The U.S. Marine Corps does not have custody of nuclear weapons in peacetime, and has not experienced an accident involving them.4.8

The U.S. Department of Defense reports that 1,243 Nuclear Weapon mishaps have occurred before 1973, 32 of which were officially designated as Broken Arrows

February 13th, 1950

B-36 / Puget Sound, Washington10.1

A B-36 was enroute from Eielson AFB to Carswell AFB on a simulated combat profile mission. The Mk410.1 aboard had a dummy capsule ball installed. After 6 hours of flight, the aircraft was at 12,000 feet of altitude. Icing conditions complicated the emergency and level flight could not be maintained. The aircraft headed out over the pacific and dropped the Mk410.1 from 8,000 feet. A bright flash occurred on impact, followed by a sound and shock wave. Only the high-explosives (HE) detonated. The aircraft was then flown over Princess Royal Island where all but one of the crew bailed out. The aircraft wreckage was later found on Mt. Kologet, about 230 miles northeast of Vancouver Island.4.1

April 11th, 1950

B-29 / Manzano Base, New Mexico

A B-29 departed Kirtland AFB at 21:38 and approximately 3 minutes later crashed into a mountain on Manzano Base, killing the crew. Detonators were installed in the Mk410.1 on board the aircraft. The bomb case was demolished, and some high-explosive material burned in the gasoline fire. Other pieces of unburned high explosive were scattered throughout the wreckage. Four space detonators in their carrying case were recovered undamaged. Contamination did not occur, and there were no recovery problems. The recovered components of the weapon were returned to the Atomic Energy Commission. The capsule of nuclear material was on board the aircraft but had not been inserted into the weapon for safety reasons. A nuclear detonation was not possible.4.1

July 13th, 1950

B-50 / Lebanon, Ohio

A B-50 was on a training mission from Biggs AFB, Texas, flying at 7,000 feet on a clear day. The aircraft nosed down and flew into the ground, killing 4 officers and 12 airmen. The high-explosive portion of the Mk410.1 aboard detonated on impact. There was no nuclear capsule aboard the aircraft.4.2

August 5th, 1950

B-29 / Fairfield-Suisun AFB, California

A B-29 carrying a Mk410.1, but no capsule, experienced two runaway propellers and landing-gear retraction difficulties on takeoff from Fairfield-Suisun AFB (now Travis AFB). The aircraft attempted an emergency landing, crashed, and burned. Fire was fought for 12-15 minutes before the weapon’s high-explosive material detonated. Nineteen crew members and rescue personnel, including General Travis, were killed in the crash or the resulting detonation.4.2

November 10th, 1950

B-50 / Over water, Outside the Continental United States

Because of an inflight aircraft emergency, a Mk410.1 containing no capsule of nuclear material was jettisoned over water from a B-50 at an altitude of 10,500 feet. A high-explosive detonation was observed.4.2

March 10th, 1956

B-47 / Mediterranean Sea

A B-47 was one of a flight of four scheduled for nonstop deployment from MacDill AFB to an overseas air base. The takeoff from MacDill and the first refueling were normal. The second refueling point was over the Mediterranean Sea. In preparation, the flight penetrated solid cloud formation to descend to the refueling level of 14,000 feet. The base of the clouds was 14,500 feet, and visibility was poor. The aircraft never made contact with the tanker. An extensive search failed to locate any trace of the missing aircraft or crew. No weapons were aboard the aircraft, only two capsules of nuclear weapon material in carrying cases. A nuclear detonation was not possible.4.2

July 27th, 1956

B-47 / RAF Lakenheath, United Kingdom

A B-47 with no weapons aboard was on a routine training mission and making a touch-and-go landing, when the aircraft suddenly went out of control. It slid off the runway and crashed into a storage igloo containing several nuclear weapons. The bombs did not burn or detonate; they were in storage configuration. No capsules of nuclear materials were in the weapons or present elsewhere in the building. There were no contamination or cleanup problems. The damaged weapons and components were returned to the Atomic Energy Commission.4.2

May 22nd, 1957

B-36 / Kirtland AFB, New Mexico

The B-36 aircraft was ferrying a Mk1710.1 from Biggs AFB, Texas, to Kirtland AFB. At 11:50 a.m., MST, as the aircraft approached Kirtland at an altitude of 1,700 feet, the weapon dropped from the bomb bay, taking the bomb bay doors with it. Weapon parachutes were deployed but apparently did not fully retard the fall because of the low altitude. The impact point was approximately 4.5 miles south of the Kirtland control tower and .3 mile west of the Sandia Base reservation. The high-explosive material detonated, completely destroying the weapon, and making a crater approximately 25 feet in diameter and 12 feet deep. Fragments and debris were scattered as far as 1 mile from the impact point. The release-mechanism locking pin was being removed at the time of release. (It was standard procedure, at that time, to remove the locking pin during takeoff and landing, to allow emergency jettison of the weapon if necessary.) The recovery and cleanup operations were conducted by Field Command, Armed Forces Special Weapons Project. Radiological survey of the area disclosed no radioactivity beyond the lip of the crater, at which point the level was 0.5 milliroentgens. There were no health or safety problems. A nuclear capsule was on board the aircraft but had not been inserted into the weapon for safety reasons. A nuclear detonation was not possible.4.3

July 28th, 1957

C-124 / Atlantic Ocean

Two Mk510.1 weapons were jettisoned from a C-124 aircraft off the east coast of the United States. The C-124 aircraft was enroute from Dover AFB, Delaware, when a loss of power from the number one and number two engines was experienced. Maximum power was applied to the remaining engines, but level flight could not be maintained. At this point, the decision was made to jettison cargo in the interest of safety of the crew and aircraft. Three weapons and one nuclear capsule were aboard the aircraft, and nuclear components had not been installed in the weapons. The first weapon was jettisoned at 4,500 feet altitude. The second weapon was jettisoned at approximately 2,500 feet altitude. No detonation occurred from either weapon. Both weapons are presumed to have been damaged from impact with the ocean surface, and to have submerged almost instantly. The ocean varies in depth in the area of the jettisons. The C-124 landed at an airfield in the vicinity of Atlantic City, New Jersey, with the remaining weapon and the nuclear capsule aboard. A search for the weapons or debris had negative results.4.3

October 11th, 1957

B-47 / Homestead AFB, Florida

The B-47 departed Homestead AFB shortly after midnight on a deployment mission. Shortly after lift-off, one of the aircraft’s outrigger tires exploded. The aircraft crashed in an uninhabited area approximately 3,800 feet from the end of the runway. The aircraft was carrying one Mk1510.1 in ferry configuration in the bomb bay and one nuclear capsule in a carrying case in the crew compartment. The weapon was enveloped in flames, and it burned and smoldered for approximately 4 hours, at which time it was cooled with water. Two low-order high explosive detonations occurred during the burning. The nuclear capsule and its carrying case were recovered intact and only slightly damaged by heat. Approximately one half of the weapon remained. All major components were damaged but were identifiable and accounted for.4.3

January 31st, 1958

B-47 / Overseas Base

A B-47 with one Mk3610.1 in strike configuration was making a simulated takeoff during an exercise alert. When the ai9rcraft reached approximately 40 knots on the runway, the left rear wheel casting failed. The tail struck the runway, and a fuel tank ruptured. The aircraft caught fire and burned for 7 hours. Firemen fought the fire for the allotted 10-minute fire-fighting time for the high-explosive contents of that weapon, and then evacuated the area. The high explosive did not detonate, but some contamination did occur in the immediate area of the crash. The contamination was detected after removal of the wreckage and the asphalt beneath it after washing down of the runway. One fire truck and one fireman’s clothing showed slight alpha contamination before washing. Following the accident, exercise alerts were temporarily suspended and B-47 wheels were checked for defects.4.4

February 5th, 1958

B-47 / Savannah River, Georgia

The B-47 was on a simulated combat mission -that originated at Homestead AFB, Florida. While near Savannah, Georgia, the B-47 had a mid-air collision with an F-86 aircraft at 3:30 a.m. Following the collision, the B-47, with a Mk1510.1 aboard, attempted to land three times at Hunter AFB, Georgia. Because of the condition of the aircraft, its airspeed could not be reduced enough to ensure a safe landing. Therefore, the decision was made to jettison the weapon rather than expose Hunter AFB to the possibility of a high-explosive detonation. A nuclear detonation was not possible since the nuclear capsule was not aboard the aircraft. The weapon was jettisoned into the water several miles from the mouth of the Savannah River (Georgia) in Wassaw Sound off Tybee Beach. The precise impact point of the weapon is unknown. The weapon was dropped from an altitude of approximately 7,200 feet at an aircraft speed of 180-190 knots. No detonation occurred. After jettison, the B-47 landed safely. A 3-square-mile area was searched by divers and underwater demolition team -technicians using galvanic drag and hand-held sonar devices. The weapon was not found. The search was terminated on 16 April 1958. The weapon was considered to be irretrievably lost.4.4

March 11th, 1958

B-47 / Florence, South Carolina

At 3:53 p.m., EST, a B-47E departed Hunter AFB, Georgia, as number three aircraft in a flight of four enroute to an overseas base. After level off at 15,000 feet, the aircraft accidentally jettisoned an unarmed Mk610.1 that impacted in a sparsely populated area 6.5 miles east of Florence, South Carolina. The bomb’s high-explosive material exploded on impact. The detonation caused property damage and several injuries on the ground. The aircraft returned to the base without further incident. No capsule of nuclear materials was aboard the B-47 or installed in the weapon.4.4

November 4th, 1958

B-47 / Dyess AFB, Texas

A B-47 caught fire on takeoff. Three crew members successfully ejected; one was killed when the aircraft crashed from an altitude of 1,500 feet. One Mk3910.1 was on board when the aircraft crashed. The resultant detonation of the high explosive made a crater 35 feet in diameter and 6 feet deep. Nuclear materials were recovered near the crash site.4.4

November 26th, 1958

B-47 / Chennault AFB, Louisiana

A B-47 caught fire on the ground. The single Mk15 Mod 2 on board was destroyed by the fire. Contamination was limited to the immediate vicinity of the weapon residue within the aircraft wreckage.4.5

January 18th, 1959

F-100 / Pacific Base

The aircraft was parked on a revetted hardstand in ground alter configuration. The external load consisted of a Mk710.1 on the left intermediate station and three fuel tanks (both inboard stations and the right intermediate station). When the starter button was depressed during a practice alter, an explosion and fire occurred when the external fuel tanks inadvertently jettisoned. Fire trucks at the scene put out the fire in about 7 minutes. The capsule was not in the vicinity of the aircraft and was not involved in the accident. There were no contamination or cleanup problems.4.5

July 6th, 1959

C-124 / Barksdale AFB, Louisiana

A C-124 on a nuclear logistics movement mission crashed on takeoff. The aircraft was destroyed by fire, which also destroyed the Mk3910.1 on-board. No nuclear or high-explosive detonation occurred; safety devices had functioned as designed. Limited contamination was present over a very small area immediately below the destroyed weapon. This contamination did not hamper rescue or fire-fighting operations.4.5

September 25th, 1959

P-5M / Pacific Ocean, Off the Washington Coast

A U.S. Navy P-5M aircraft assigned to Naval Air Station, Whidbey Island, Washington, crashed in the Pacific Ocean about 100 miles west of the Washington-Oregon border. It was carrying an unarmed Mk710.1 weapon containing no nuclear material. The weapon was not recovered.4.5

October 15th, 1959

B-52 & KC-135 / Hardinsburg, Kentucky

The B-52 departed Columbus AFB, Mississippi, at 2:00 p.m., CST. The aircraft assumed the number two position in a flight of two. The KC-135 departed Columbus AFB at 5:33 p.m., CST, as the number two tanker aircraft in a flight of two scheduled to refuel the B-52’s. Rendezvous for refueling was accomplished in the vicinity of Hardinsburg, Kentucky, at 32,000 feet. It was night; the weather was clear, with no turbulence. Shortly after the B-52 began refueling from the KC-135, the two aircraft collided. The instructor pilot and pilot of the B-52 ejected, followed by the electronic warfare officer and the radar navigator. The copilot, navigator, instructor navigator, and tail gunner failed to leave the B-52. All four crew members in the KC-135 were fatally injured. The B-52’s two unarmed Mk15 Mod 210.1 weapons were recovered intact. One had been partially burned, but did not result in dispersion of nuclear material or other contamination.4.5

June 7th, 1960

BOMARC / McGuire AFB, New Jersey

A BOMARC (CIM-10) air defense missile in ready storage condition (permitting launch in 2 minutes) in Shelter 204 of Site RW-019.1 was destroyed by explosion and fire after a high-pressure helium tank exploded and ruptured the missile’s fuel tanks. The Mk406.9, 10.1 was also destroyed by the fire, although the high explosive did not detonate. Nuclear safety devices functioned as designed. The fire burned uninhibited for approximately 30 minutes. Fire-fighting activities were conducted for 15 hours using water as a suppressant. As a result, materials from the shelter flowed under the front shelter doors, down the asphalt apron and street between the row of shelters, and into the drainage ditch leading outside the site boundary fence. The primary material of concern is weapons grad plutonium (WGP). It was estimated that 300g of WGP was not recovered from the initial accident response actions, which, in a dioxide chemical form, is about one fluid once.9.1 Contamination was restricted to an area immediately beneath the weapon and an adjacent elongated area approximately 100 feet long, caused by drain-off of fire-fighting water.4.5 The residue was sent to the Medina Modification Center. Frank Dunn, Los Alamos National Laboratory (LASL); Wayne Earl, ALO; and Maynard Cowan, Sandia Labs; responded to the accident. EOD consisted of recovery of weapon parts.6.9

January 3rd, 1961

USS Saratoga / Ionian Sea

The USS Saratoga (CVA-60) suffers a fire2.1 caused by a ruptured oil line in-route to Athens Greece in the Ionian Sea, killing seven.1.1 CV-60 is a Forrestal-Class aircraft carrier, certified to carry the Mk43, Mk57, and Mk61.3.1

January 24th, 1961

B-52 / Goldsboro, North Carolina

During a B-52 airborne alert mission, structural failure of the right wing resulted in two weapons separating from the aircraft during aircraft breakup at 2,000-10,000 feet. One bomb parachute deployed, and the weapon received little impact damage. The other bomb fell free and broke apart upon impact. No explosion occurred. Five of the eight crew members survived. A portion of one weapon, containing uranium, could not be recovered despite excavation in the waterlogged farmland to a depth of 50 feet. The Air Force subsequently purchased an easement requiring permission for anyone to dig there. No detectable radiation and no hazard exist in the area.4.6

Two Mk39 Mod 2 bombs (serial numbers 434909 & 359943) were involved.6.8

Weapon 434909 (without ALT 197); It appeared that, after the majority of the crew had departed, the plane’s fuselage separated at a point between the forward and aft bomb bay sections. This is now presumed to have been a longitudinal separation combined with a torsion breakup of the airframe. During, or immediately after this separation, weapon 434909 twisted from its rack and fell away from what remained of its aft bomb bay section. Minor scars inflicted on the exterior of the bomb by its sway-braces indicate that it left the rack, nose first, with a slight clockwise rotation. From this rack, only the unbroken chain has been recovered.6.9

The safing pins had been removed from the bomb’s arming rods, presumably when longitudinal separation of the fuselage jerked the lanyard to which they were attached. As weapon 434909 left its rack, therefore, the arming rods were pulled in the manner of an intentional drop sequence and the Single Pulse Generator (MC845) was actuated.6.9

Its static line being intact, the bomb’s parachutes deployed normally and it landed nose down approximately one mile east of the point of aircraft impact. Weapon 434909 remained upright with its nose buried about 18 inches into the sandy clay. It was located easily since the large parachute was draped in nearby trees.6.9

On 24 January, weapon 434909 was disassembled, by members of an Air Force EOD team from Wright-Patterson AFB, who performed the following:  With the nose dented (crush switches actuated) the weapon was secured in the upright position. Tritium monitoring was performed, none was detected, then the afterbody was removed and all necessary electrical disconnections were made as well as the alignment plate removed. The gas-transfer tube was crimped in two places about two inches apart then cut, tritium detection was performed again with a T290A with none indicated. EOD repeated this procedure for the gas transfer tube into the pit and the detonator was removed from under the reservoir. A sling was attached to the polar cap support then all bolts removed and the high-explosive (HE) and nuclear assembly was removed and lowered onto cushions. All detonators removed except the one under the X-unit. The X-unit was then removed with the final detonator. The remainder of the bomb was removed from the ground and its components returned to the 53rd Munitions Maintenance Squadron, Seymour Johnson AFB. Except for a broken nose plate, weapon 434909 appeared to have sustained negligible damage.6.9

Weapon 359943 (the un-retarded unit) went into the ground and came apart on impact. After digging for sever days (24-27) about half of the alignment plate was exposed. The Hi-Pac, HVAS Switch, Reservoir, Resistor Connector box, and case with spare detonators were identified. The reservoir was removed and gas transfer tube crimped (the gas transfer tube had been severed upon impact), tritium monitoring was performed with none detected. On the 28th, the excavation team began finding pieces of the HE assembly and some detonators and on the 29th the main HE and nuclear assembly section and additional detonators were exposed. On the 30th additional pieces of HE, detonators and the pit were recovered. The EOD team stood by to recover additional pieces. Heavier equipment continued excavating but the rest of the weapon was not recovered. All recovered material from weapon 359943 was shipped back to Medina Modification Center.6.10

March 14th, 1961

B-52 / Yuba City, California

A B-52 experienced failure of the crew compartment pressurization system, forcing descent to 10,000 feet altitude. Increased fuel consumption caused fuel exhaustion before rendezvous with a tanker aircraft. The crew bailed out at 10,000 feet except for the aircraft commander, who stayed with the aircraft to 4,000 feet and steered the plane away from a populated area. The two Mk3910.1 weapons on board were torn from the aircraft on ground impact. The high explosive did not detonate. Safety devices worked as designed to prevent nuclear contamination.4.6

October 19th, 1961

Jupiter IRBM / Italy

A Jupiter (PGM-19) missile armed with a Mk49 warhead, while deployed to Italy, was struck by lightning, resulting in deuterium-tritium boosting gas being injected into the warhead pit and activation of thermal batteries in the adaption kit. The missile was returned to operational status after 76 days. On November 4, 1961 the warhead was flown back to the AEC’s Clarksville Modification Center for post-mortem examination.7.1

November 6th, 1961

W47 / Pantex Ordnance Plant, Amarillo, Texas

During the disassembly of an early model Mk47, the gas transfer system ruptured, permitting the helium inside the pit to escape (the pit was kept filled with helium to detect leaks during storage). The helium gas was contaminated by the radioactive plutonium in the pit. Three men working in the area heard the “hissing” caused by the escaping helium gas and immediately evacuated the area. Two men working on the pit were wearing respirators; all three men washed off some contamination on their skin and clothing. Three days were required to decontaminate the removeable Mk47 handling equipment and another two weeks were required to decontaminate the accident area. The U.S. Army Ordnance Corps representative at Pantex made the following announcement to the news media:7.1

Three Mason and Hanger-Silas Mason C., Inc. employees were involved in a minor radiation incident on November 6th at the Pantex Ordnance Plant near Amarillo, Texas. The incident occurred during a routine operation involving radioactivate materials. Medical examination of the three men, who have not lost any work time as a result of the incident, will be continued as a routine matter. There was no escape of radiation into the atmosphere.7.1

November 13th, 1963

AEC Storage Igloo / Medina Modification Center, Texas

An explosion involving 123,000 pounds of high-explosive components of nuclear weapons caused minor injuries to three Atomic Energy Commission employees. There was little contamination from the nuclear components, which were stored elsewhere in the building. The components were from the disassembly of obsolete weapons.4.6, 8.1

January 13th, 1964

B-52 / Cumberland, Maryland

A B-52D was enroute from Westover AFB, Massachusetts, to its home base at Turner AFB, Georgia. The crash occurred approximately 17 miles southwest of Cumberland, Maryland. The aircraft was carrying two Mk5310.1 weapons, which were in a tactical ferry configuration (no mechanical or electrical connections had been made to the aircraft, and the safing switches were in the “SAFE” position). Before the crash, the pilot had requested a change of altitude because of severe air turbulence at 29,500 feet. The aircraft was cleared to climb to 33,000 feet. During the climb, the aircraft encountered violent air turbulence, and aircraft structural failure then occurred. Of the five air-crew members, only the pilot and copilot survived. The gunner and navigator ejected, but died of exposure to subzero temperatures after successfully reaching the ground. The radar navigator did not eject and died upon aircraft impact. The crash site was an isolated mountainous and wooded area. The 14 inches of new snow covered the aircraft wreckage, which was scattered over an area of approximately 100 square yards. The weather during the recovery and cleanup operation involved extreme cold and gusty winds. Both weapons remained in the aircraft until it crashed, and were relatively intact in the approximate center of the wreckage area.4.6

December 5th, 1964

Minuteman IB ICBM / Ellsworth AFB, South Dakota

Under command of the 44th Strategic Missile Wing, the Minuteman IB (LGM-30B) missile was on strategic alert at Launch Facility L-02, Ellsworth AFB, South Dakota and was fitted with a Mk11 aeroshell containing a Mk56 Mod 1 warhead.6.2 At 1500 (MST) two airmen were dispatched to the Launch Facility to repair the inner zone security system. In the midst of their checkout of the inner zone system, one retrorocket in the spacer below the Reentry Vehicle (RV) fired, causing the RV to fall about 75 feet to the floor of the silo. When the RV struck the bottom of the silo, the arming and fusing/altitude control subsystem containing the batteries was torn loose, thus removing all sources of power from the RV. The RV structure received considerable damage. All safety devices operated properly in that they did not sense the proper sequence of events to allow arming the warhead. There was no detonation or radioactive contamination.4.7

Around 2000 (MST), Mr. D. P. Dickason, ALO, was notified by the Director of Nuclear Safety at Kirtland AFB that some squibs had fired on a Minuteman missile and that a potential Broken Arrow had been declared. Mr. Dickason subsequently notified Lawrence Radiation Laboratory (LRL) and Sandia Corporation (SC) of the situation. By midnight it was still unclear if any action by the laboratories was needed. At 0600 (PST), 6 December, Mr. D. M. Olson, Sandia Corporation, Sandia Laboratory (SCSL), and Mr. Dickason called Mr. R. K. Petersen, Sandia Corporation Livermore Laboratory (SCLL), and stated that the aeroshell had fallen 75 feet to the silo floor. They informed him that the Director of Nuclear Safety at Kirtland AFB was sending a team of observers to Ellsworth AFB and that AEC/DMA wanted an ALO representative to accompany them. It was decided that an SCLL representative should meet the team in Denver and proceed to Ellsworth AFB.6.2

It was also decided at this time that an LRL representative probably was not required. Mr. M. D. Martin, LRL, was had been previously informed of the situation, was contacted and concurred. He asked to be notified of the conditions at the silo and stated that he would then send someone if the situation warranted it. The group of observers consisted of Mr. D. P. Dickason, AEC/ALO; Lt. Col. J. O. Mitchell, USAF/DNS; Maj. H. B. Lacy, USAF/DNS; Capt. D. J. Loosley, USAF/AFWL; and Mr. R. K. Petersen, SCLL. The group arrived Ellsworth AFB, South Dakota, at 145 (MST), 6 December, and went immediately to the office of Lt. Col. J. W. Eskridge, Director of Safety, 44th Strategic Missile Wing. There the group was briefed, as follows: At 1400 (MST) 5 December, two airmen entered L-02 to investigate an inner-zone (IZ) security alarm. They opened the personnel access door and descended to the equipment room to conduct a routine check of the IZ and outer-zone (OZ) security circuitry. The check consisted, in part, of removing a fuze and observing the operation of a relay to determine continuity. When the fuze had been removed and reinserted the third time there was a violent explosion. This explosion occurred at approximately 1500 (MST). About one hour later the two airmen returned in the company of a third airman and after a cursory inspection through openings in the launch tube reported that the aeroshell was missing.6.2

The Group of observers then reported to the Command Post and Col. V. M. Cloyd, Commander, 44th Strategic Missile Wing. Here they were able to monitor, via remote hookup, the progress of the explosive ordnance disposal (EOD) team as it entered the silo at 1700 (MST). The EOD team was to: 1. Safe the ignitors on the missile; 2. Disconnect the ignitor batteries at the J-Box; 3. Safe and remove the RV attitude-control rockets (which were still lying on top of the missile); and 4. Inspect the aeroshell at the bottom of the silo (this is the first close look at the aeroshell).6.3

After completion of items 1, 2, and 3, Capt. M. M. Costa, 2701 EOD, Ellsworth AFB, and Capt. E. S. Tschirhart, Ogden Air Materiel Area (OOAMA), Hill AFB, descended to the bottom of the silo. They reported: 1. Some abrasions were present on the first and second stage rockets; 2. Debris from the exit nose cone was present at the missile support ring Number 1; 3. The “firing set” was lying on the floor, 6 feet from the aeroshell (this was later identified as the AF/AC); 4. No contamination was indicated by monitoring equipment; and 5. The aeroshell was damaged and lying partially under one of the base legs of the missile support ring.6.3

At 0800, 7 December, the observers met with Col. J. V. Farley, 341 Strategic Missile Wing (SMW), Malmstrom AFB, and offered their services. Col. Farley was President of the 15th Air Force Accident Investigation Board that had been formed to investigate this accident. He invited the group to attend the briefing the EOD was about to present. The EOD team leader, Capt. Tschirhart, presented his group’s observations with the aid of color slides taken during the inspection the previous night.6.3

Capt. Tschirhart reported that one retrorocket had fired and stated that this had caused the aeroshell to separate and fall to the bottom of the silo. He reported that the “firing set” had broken loose and that the tritium bottle was exposed to view but seemed intact. Further, Capt. Tschirhart was certain that the warhead high explosive (HE) had broken up. Capt. Tschirhart recommended removing the aeroshell with modified aeroshell handling equipment and then disassembling and disposing of it somewhere at Ellsworth AFB.6.4

After the briefing, Mr. Martin and Mr. N. D. Benedict of LRL were contacted. By using an EOD manual at each end of the telephone conversation, the following was relayed: 1. The “firing set” had separated from the aeroshell and was lying about 6′ away; 2. Some water containing a yellow substance (perhaps sodium dichromate from the cooling system) was on the floor of the silo; 3. All monitoring equipment registering low readings; 4. Avcoating and ablative material were shattered; 5. REDACTED; 6. The reservoir was intact; 7. REDACTED; 8. The sides of the case were not ruptured; 9. The nose of the aeroshell was off and the forward end of the aeroshell was caved in and split. 10. Impact crystals were visible through the aeroshell shell; 11. The warhead was visible through the aeroshell shell; 12. There was no apparent damage to the HE nuclear outer structure, however,  the HE had probably fractured; and 13. The missile showed abrasive marks but no punctures.6.4

It was apparent that items 1, 5, 6, and 7 did not correlate. It was also apparent to Mr. Martin and Mr. Benedict that item 12 might not be a good estimation of the situation. Mr. Benedict did not think that the HE had fractured but he felt other damage might have been done.6.4

Mr. Martin subsequently requested that the aeroshell not be moved until Mr. Benedict arrived to assay the situation. The request was relayed and the Air Force agreed to wait.6.5

Mr. Benedict arrived at 0800 (MST) 7 December. He was briefed and was shown slides of the aeroshell. The group of observers received permission to enter L-02 the next morning to conduct a first-hand investigation.6.5

On 8 December, the observers went down the silo at L-02. The following observations were made: 1. The missile had some minor abrasions on the side of the second and first stages. 2. The gas reservoir was intact but leaning to one side; 3. REDACTED; 4. The electrical component deck had moved forward 1 to 2 inches and was dented; 5. REDACTED; 6. The outer portions of the firing set had been blackened; and 7. The flare was flattened (with a major diameter of approximately 30 inches and a minor diameter of approximately 26 inches.6.5

Mr. Benedict decided that the only way to bring the unit up would be nose down in a cargo net with the net strapped to the unit. Any render-safe procedures would be done at a magazine, thereby minimizing personnel hazards.6.5

The Accident Investigation Board met at 2030. Mr. Benedict briefed them as follows regarding his opinion of the condition of the warhead; 1. The step joint in the flare section had opened 30 to 50 mils, either because of sheared rivers, elongated holes, or both; 2. The warhead pit seal had probably not opened (no alpha readings); 3. the reservoir was intact; and 4. REDACTED.6.5

The Board was also informed that the warhead was electrically inert since the power supplies had been torn away and there was no reason to suspect that any residual electrical charges were present.6.6

Mr. Benedict presented his plans for aeroshell recovery to the Accident Investigation Board. In conjunction with Mr. Benedict’s plan, outlined previously, Mr. Petersen had recommended that the warhead should come up isolated electrically from the hoisting crane and other ground points since circulating ground currents in the area were undetermined. The rocket engineers now became alarmed that the possibility of static discharge, due to the cold, dry climate and the nylon cargo net. Mr. Petersen then recommended a high-resistance grounding circuit and confirmed its adequacy with Mr. J. S. Anderson, SCLL. The EOD built the device for attachment to the aeroshell and the Board approved its use.6.6

Strategic Air Command (SAC), 15th Air Force, BSD, and others approved the plan for removal of the aeroshell on 9 December. A mobile crane was positioned over the silo. The aeroshell was manually moved to a hoisting position and then raised slightly with the crane and a strap. A heavy nylon cargo net was slipped under the aeroshell and securely strapped to the unit. The grounding cable and a safety rope were attached. The aeroshell was then hoisted out in a nose-down attitude and cleared the silo at approximately 1650 (MST).6.6

The aeroshell was immediately transferred to an aeroshell van, where it was suspended from an overhead, track-mounted hoist. The nose was rested on mattresses with the hoist used to maintain vertical alignment and cargo tie down straps used to prevent lateral motion. The aeroshell was moved from L-02 to Ellsworth AFB on 10 December.6.6

Mr. Benedict had requested radiographers, a radiation safety specialist and their equipment, from LRL. Mr. W. T. Fritts and Mr. F. F. Sojka were the radiographers and Mr. G. E. Costella was the radiation safety specialist.6.6

The aeroshell arrived at Ellsworth AFB at 1630 10 December and was taken to a magazine for render-safe procedures. At 2100 the Deuterium-Tritium (DT) reservoir was removed and radiographers were taken to determine the condition of the internal parts. The radiographs were reviewed in the early hours of 11 December and indicated no cracked HE and no deformation of the pit.6.6

It was concluded that with some further disassembly and proper packaging the unit was safe for shipment to the Medina Modification Center.6.7

Security and public relations were handled by the 44th SMW and Ellsworth AFB. No release concerning this incident was made to the press. The entire operation was handled in such a way that the nervy communities were not aware of and did not exhibit even a mild interest in the operation.6.7

At the time of this writing (1965), a post-mortem had not been conducted. There is no reason to suspect that any of the warhead electrical components were actuated. The warhead component deck will be shipped to SCLL from Medina for post-mortem of components by the design group responsible.6.7

December 8th, 1964

B-58 / Bunker Hill AFB (now Grissom AFB), Indiana

SAC aircraft were taxiing during an alert exercise. As one B-58 reached a position directly behind the aircraft on the runway ahead of it, the aircraft ahead` brought advanced power. As a result of the combination of the jet blast from the aircraft ahead, the icy runway surface conditions, and the power applied to the aircraft while attempting to turn onto the runway, control was lost and the aircraft slid off the left side of the taxiway. The left main landing gear passed over a flush-mounted taxiway light fixture, and 10 feet farther along in its travel, grazed the left edge of a concrete light base. After another 10 feet, the left main landing gear struck a concrete electrical manhole box, and the aircraft caught on fire. When the aircraft came to rest, all three crew members aboard abandoned the aircraft. The aircraft commander and defensive systems operator egressed with only minor injuries. The navigator ejected in his escape capsule, which impacted 548 feet from the aircraft. He did not survive. Portions of the nuclear weapon on board burned. Contamination was limited to the immediate area of the crash and was subsequently removed.4.7 The B-58 was carrying one Mk53 internally, and four Mk43 bombs externally, the Mk43 serial numbers were 92426, 86766, 93315, and 96642. All weapons were equipped with Type 79 pits and were extracted in 2A containers. The residue from the weapons (except for the High Explosives (HE) which was burned at Bunker Hill) from the weapons was shipped from Bunker Hill to Clarksville Facility in containers. The Type 79 pits were shipped to Rocky Flats for disposition with other components from the radiation case shipped to Oak Ridge and Y-12 for disposition.6.1

October 11th, 1965

C-124 / Wright-Patterson AFB, Ohio

The C-124 aircraft was being refueled in preparation for a routine logistics mission when a fire occurred at the aft end of the refueling trailer. The fuselage of the aircraft, containing only components of nuclear weapons and a dummy training unit, was destroyed by the fire. There were no casualties. The resultant radiation hazard was minimal. Minor contamination was found on the aircraft, cargo, and clothing of explosive ordnance disposal and fire-fighting personnel, and was removed by normal cleaning.4.7

December 5th, 1965

B43 / Pacific Ocean

Two Mk43 weapons, while mated to an aircraft, were lost at sea when the aircraft rolled off of the aircraft carrier elevator.10.1

January 17th, 1966

B-52 & KC-135 / Palomares, Spain

The B-52 and the KC-135 collided during a routine high-altitude-air refueling operation. Both aircraft crashed near Palomares, Spain. Four of the eleven crew members survived. The B-52 carried four Mk2810.1 weapons. One was recovered on the ground, and one was recovered from the sea on 7 April after extensive search and recovery efforts. Two of the weapons’ high-explosive materials exploded on impact with the ground, releasing some radioactive materials. Approximately 1400 tons of slightly contaminated . soil and vegetation were removed to the United States for storage at an approved site. Representatives of the Spanish Government monitored the cleanup operation.4.8

January 21st, 1968

B-52 / Thule, Greenland

A B-52 from Plattsburgh AFB, New York, crashed and burned approximately 7 miles southwest of the runway at Thule AB, Greenland, while approaching the base to land. Six of the seven crew members survived. The bomber carried four nuclear weapons, all of which were destroyed by fire. Some radioactive contamination occurred in the area of the crash, which was on the sea ice. Some 237,000 cubic feet of contaminated ice, snow, water, and crash debris were removed to an approved storage site in the United States over the course of a 4-month operation. Although an unknown amount of contamination was dispersed by the crash, environmental sampling showed normal readings in the area after the cleanup was completed. Representatives of the Danish Government monitored the cleanup operations.4.8

May 22nd, 1968

USS Scorpion / Atlantic Ocean

The Skipjack-class submarine USS Scorpion (SSN 589) sank due to unknown causes, there were two Mk45 ASTOR torpedoes with two Mk3410.1 warheads aboard. The special nuclear material (plutonium and highly enriched uranium) has not been recovered. It can be assumed with certainty that the integrity of the weapons was compromised due to sea pressure and that the weapons were exposed to seawater immediately after the sinking. Periodic monitoring of sea water, marine life and sediment from the wreck site has not detected plutonium in excess of that expected from fallout from past atmospheric weapons testing nor uranium in excess of natural background concentrations. No significant environmental impact is expected.

September 19th, 1980

Titan II ICBM / Damascus, Arkansas

During routine maintenance in a Titan II (LMG-25C) silo, an Air Force repairman dropped a heavy wrench socket, which rolled off a work platform and fell toward the bottom of the silo. The socket bounced and struck the missile, causing a leak from a pressurized fuel tank. The missile complex and the surrounding area were evacuated, and a team of specialists was called in from Little Rock AFB, the missile’s main support base. About. 8.5 hours after the initial puncture, fuel vapors within the silo ignited and exploded. The explosion fatally injured one member of the team. Twenty-one other USAF personnel were injured. The missile’s reentry vehicle, which contained a Mk5310.1 warhead, was recovered intact. There was no radioactive contamination.4.8

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