Revision 133504624 of "Benutzer:Quotengrote\/1968 Thule Air Base B-52 crash" on dewiki

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{{Infobox aircraft occurrence
| name            = 1968 Thule Air Base B-52 crash
| image           = Boeing B-52G in flight 061026-F-1234S-021.jpg
| image_size      = 250
| caption         = A B-52G, similar to the one that crashed at Thule Air Base
| date            = January 21, 1968
| type            = In-flight fire
| occurrence_type = Accident
| site            = {{convert|7.5|mi|km}} West of [[Thule Air Base]] (was [[Pituffik]]),<br />[[Greenland]]
| coords          = {{coord|76|31|40|N|69|16|55|W|display=inline,title|scale:50000_region:GL_type:event}}{{sfn|Project Crested Ice 1969: The Thule Accident|p=9}}

<!--These 17 entries for single-aircraft accidents:------>
| aircraft_type   = [[B-52 Stratofortress|B-52G Stratofortress]]
| aircraft_name   = 
| operator        = [[380th Air Expeditionary Wing|380th Strategic Bomb Wing]], [[Strategic Air Command]], [[United States Airforce]]
| tail_number     = 58-0188
| origin          = [[Plattsburgh Air Force Base]]
| stopover        = 
| stopover0       = 
| stopover1       = 
| stopover2       = 
| stopover3       = 
| last_stopover   = 
| destination     = Plattsburgh Air Force Base{{sfn|Foreign Relations of the United States 1964–1968: Denmark|p=}}{{page needed|date=June 2011}}
| passengers      = 0
| crew            = 7
| injuries        = 
| fatalities      = 1
| survivors       = 6
}}

The '''1968 Thule Air Base B-52 crash''', '''Thule affair''' or '''Thule accident''' ({{IPA-en|ˈtuːliː|pron}}) was an accident on January&nbsp;21, 1968, involving a [[United States Air Force]] (USAF) [[B-52 Stratofortress|B-52 bomber]]. The aircraft was carrying four [[hydrogen bomb]]s on a [[Cold War]] "[[Operation Chrome Dome|Chrome Dome]]" alert mission over [[Baffin Bay]] when a cabin fire forced the crew to abandon the aircraft before they could carry out an [[emergency landing]] at [[Thule Air Base]]. Six crew members ejected safely, but one who did not have an [[ejection seat]] was killed while trying to bail out. The bomber crashed onto [[sea ice]] in [[North Star Bay]],<ref group="Note">Also known as Bylot Sound.</ref> [[Greenland]], causing the nuclear payload to rupture and disperse, which resulted in widespread [[radioactive contamination]].{{Citation needed|date=June 2012}}

The United States and [[Denmark]] launched an intensive clean-up and recovery operation, but the [[Teller–Ulam design#Basic principle|secondary]] of one of the nuclear weapons could not be accounted for after the operation completed. USAF [[Strategic Air Command]] "Chrome Dome" operations were discontinued immediately after the incident, which highlighted the safety and political risks of the missions. Safety procedures were reviewed and more stable explosives were developed for use in nuclear weapons.

In 1995, a political scandal resulted in Denmark after a report revealed the government had given tacit permission for nuclear weapons to be located in Greenland, in contravention of Denmark's 1957 [[nuclear-free zone]] policy. Workers involved in the clean-up program have been campaigning for compensation for [[Radiation poisoning|radiation-related illnesses]] they experienced in the years after the incident. In March 2009, ''[[Time (magazine)|Time]]'' identified the accident as one of the world's worst nuclear disasters.{{sfn|Time 2009—Worst Nuclear Disasters}}

== Thule Monitor Mission ==
[[File:Thule BMEWS.jpg|thumb|left|BMEWS antennas at Thule, with a modern Satellite Control Network [[radome]] on the right|alt=A series of four metal structures silhoutted on the horison, with a golf ball looking dome to the right]]
In 1960, the USAF Strategic Air Command (SAC) began [[Operation Chrome Dome]], a peacetime airborne alert program to fly nuclear-armed B-52 Stratofortresses to the borders of the Soviet Union. The flights were scheduled to ensure that up to twelve bombers were aloft at all times.{{sfn|Time 1961—Deadly Daily Dozen}}{{sfn|Croddy|Wirtz|2005|p=3}} These bombers gave SAC offensive capability in the event of a Soviet [[first strike]],{{sfn|Clarke|2006|pp=70–73}} and provided a significant Cold War [[nuclear deterrent]].{{sfn|Croddy|Wirtz|2005|p=3}} Beginning in 1961, B-52 bombers also flew secret "Hard Head" missions (or "Thule Monitor Missions") over Thule Air Base with the purpose of maintaining visual surveillance of the base's strategically important [[Ballistic Missile Early Warning System]] (BMEWS), which provided early warning of Soviet missile launches.{{sfn|Project Crested Ice 1969: The Thule Accident|p=5}} If the communication link between [[North American Aerospace Defense Command]] and the base was severed, the aircraft crew could determine if the interruption resulted from an attack or a technical failure.{{sfn|Croddy|Wirtz|2005|p=3}}{{sfn|Sagan|1995|pp=170–176}}<ref group="Note">Satellite verification and monitoring were not possible at the time.</ref> The monitoring mission started when the designated aircraft reached a [[waypoint]] at {{coord|75|0|N|67|30|W|type:landmark|display=inline}} in Baffin Bay and entered a figure-eight [[Holding (aviation)|holding pattern]] above the air base at an altitude of {{convert|35000|ft|m}}.{{sfn|Project Crested Ice 1969: The Thule Accident|p=5}}

{{Location map+|Greenland|width=180|float=right|caption=Greenland|alt=Map of Greenland showing the location of Thule on its northwestern shore|places=
{{Location map~|Greenland|lon_dir=W|lat_dir=N|lat_deg=76|lat_min=31|lon_deg=69|lon_min=13|label=Thule&nbsp;Air&nbsp;Base|position=right}}
{{Location map~|Greenland|lon_dir=W|lat_dir=N|lat_deg=73|lat_min=24|lon_deg=68|lat_min=8|label=Baffin Bay|position=right}}
}}
In 1966, [[United States Secretary of Defense]] [[Robert McNamara]] proposed cutting "Chrome Dome" flights because the BMEWS system was fully operational, the bombers had been made redundant by missiles, and $123&nbsp;million (${{Formatprice|{{Inflation|US|123000000|1966|r=-4}}|0}} as of {{CURRENTISOYEAR}}) could be saved. SAC and the [[Joint Chiefs of Staff]] opposed the plan, so a compromise was reached whereby a smaller force of four bombers would be on alert each day. Despite the reduced program and the risks highlighted by a 1966 [[1966 Palomares B-52 crash|B-52 crash in Spain]], SAC continued to dedicate one of the aircraft to monitoring Thule Air Base. This assignment was without the knowledge of civilian authorities in the United States, who SAC determined did not have the "[[need to know]]" about specific operational points.{{sfn|Sagan|1995|pp=178–180}}

== Broken Arrow ==
On January&nbsp;21, 1968, a B-52G Stratofortress, serial number 58-0188, with the callsign "HOBO 28"{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=2}} from the [[380th Air Expeditionary Wing|380th Strategic Bomb Wing]] at [[Plattsburgh Air Force Base]], New York was assigned the "Hard Head" mission over Thule and nearby [[Baffin Bay]].{{sfn|B-52 Crash at Thule Air Base 1968—USAEC|p=38}}  The bomber crew consisted of five regular crew members including Captain John Haug, the aircraft commander. Also aboard was a substitute navigator (Captain Curtis R. Criss{{sfn|Dresser|1970|pp=25–26}}), and a mandatory third pilot—Major Alfred D'Mario.<ref>{{cite report | title = USAF Accident/Incident Report | date = 1968-01-21 | accessdate = 2009-03-20 | publisher = United States Air Force }}</ref>

Before take-off, D'Mario placed three cloth-covered foam cushions on top of a heating vent under the instructor navigator's seat in the aft section of the lower deck. Shortly after take-off, another cushion was placed under the seat. The flight was uneventful until the scheduled mid-air refueling from a [[KC-135 Stratotanker]], which had to be conducted manually because of an error with the B-52G's autopilot. Approximately one hour after refueling, while the aircraft was circling above its designated area, Captain Haug directed co-pilot Svitenko to take his rest period. His seat was taken by D'Mario. The crew was uncomfortable because of the cold, despite the heater's [[Potentiometer#Rheostat|rheostat]] being turned up—D'Mario opened an [[Bleed air|engine bleed valve]] to increase the cabin's temperature by drawing additional hot air into the heater from the engine manifold.{{sfn|Project Crested Ice 1969: The Thule Accident|p=5}} As a result of a heater malfunction, the temperature drop between the engine manifold and the cabin's heating ducts was negligible; during the next half hour, the cabin's temperature became uncomfortably hot,{{sfn|Eriksson|2002|p=11}} and the stowed cushions ignited.{{sfn|Project Crested Ice 1969: The Thule Accident|p=3}} A member of the crew reported smelling burning rubber, and a search was mounted for the fire. The navigator searched the lower compartment twice before discovering the fire behind a metal box.{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=2}} He attempted to fight it with two fire extinguishers, but could not put out the blaze.{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=2}}{{sfn|Project Crested Ice 1969: The Thule Accident|p=7}}

[[File:Thule air base above.jpeg|thumb|left|Thule Air Base in the foreground with North Star Bay, which was covered in sea ice at the time of the accident, in the background|alt=Aerial photograph of Thule Air Base with North Star Bay in the background. Land masses are show covered in snow, but the bay is not frozen over.]]
At 15:22&nbsp;EST, approximately six hours into the flight and {{convert|90|mi|km}} south of Thule Air Base, Haug declared an emergency. He advised Thule [[air traffic control]] that he had a fire on board and requested permission to perform an emergency landing at the air base.{{sfn|B-52 Crash at Thule Air Base 1968—USAEC|p=7}} Within five minutes, the aircraft's fire extinguishers were depleted, electrical power was lost and smoke filled the cockpit to the point that the pilots could not read their instruments.<ref name="InterimReport">AEC Observers' Interim Report of Thule Accident, 1968</ref> As the situation worsened, the captain realised he would not be able to land the aircraft and advised the crew to prepare to abandon it instead. They awaited word from D'Mario that they were over land—when he confirmed that the aircraft was directly over the lights of Thule Air Base, the four crewmen ejected, followed shortly thereafter by Haug and D'Mario. The co-pilot, Leonard Svitenko, did not have an ejection seat and sustained fatal head injuries when he attempted to bail out through one of the lower hatches.{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=4}}{{sfn|Project Crested Ice 1969: The Thule Accident|p=7}}

The pilotless aircraft initially continued north, then turned left through 180° and crashed onto sea ice in North Star Bay—about {{convert|7.5|mi|km}} west of Thule Air Base—at 15:39&nbsp;EST.{{#tag:ref|Some sources say [[Wolstenholme Fjord]] is a more accurate description of the area.{{sfn|Project Crested Ice 1969: The Thule Accident|p=7}}|group=Note}} The conventional [[explosive material#High explosives|high explosive]] (HE) components of four 1.1&nbsp;[[TNT equivalent|megaton]]{{sfn|Taagholt|Hansen|2001|p=42}} [[B28 nuclear bomb|B28FI model hydrogen bombs]] detonated on impact, spreading [[radioactive contamination|radioactive material]] over a large area in a similar manner to a [[dirty bomb]].{{sfn|Vantine|Crites|2003}} A [[Nuclear fission|nuclear explosion]] was not triggered. The extreme heat generated by the burning of 225,000&nbsp;pounds of aviation fuel during the five to six hours after the crash melted the ice sheet, causing wreckage and munitions to sink to the [[ocean floor]].

[[File:Thule AFB B-52 Gunner Rescue.jpg|thumb|The gunner (center), SSgt Calvin Snapp, is rescued after ejecting onto the ice|alt=Black and white photograph of an airman in a bomber jacket being assisted to walk by two men]]
Haug and D'Mario parachuted onto the grounds of the air base and made contact with the base commander within ten&nbsp;minutes of each other. They informed him that at least six crew ejected successfully and the aircraft was carrying four nuclear weapons.{{sfn|Dresser|1970|pp=25–26}} Off-duty staff were mustered to conduct search and rescue operations for the remaining crew members. Due to the extreme conditions of the weather, arctic darkness, and unnavigable ice, the base relied largely on the Thule representative of the Royal Greenland Trade Department, Ministry of Greenland, Mr. Jens Zinglersen, to raise and mount the search using native dog sled teams.{{sfn|Hunziker|pp=13}} Three of the survivors landed within {{convert|1.5|mi|km}} of the base and were rescued within two&nbsp;hours.{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|pp=3–4}}{{sfn|Project Crested Ice 1969: The Thule Accident|p=8}} For his initial actions and later services, Mr. Zinglersen received the Air Force Exceptional Civilian Service Medal on 26 February 1968 at the hands of the U.S. Ambassador, K.E. White.{{sfn|Dresser|1970|pp=25–26}} Captain Criss, who was first to eject, landed {{convert|6|mi|km}} from the base—he remained lost on an ice floe for 21&nbsp;hours and suffered [[hypothermia]] in the {{convert|-23|F|C}} temperatures,{{sfn|Dresser|1970|pp=25–26}} but he survived by wrapping himself in his parachute.{{sfn|Dresser|1970|pp=25–26}}{{sfn|Project Crested Ice 1969: The Thule Accident|p=8}}

An aerial survey of the crash site immediately afterwards showed only six engines, a tire and small items of debris on the blackened surface of the ice.{{sfn|B-52 Crash at Thule Air Base 1968—USAEC|p=}}{{page needed|date=June 2011}} The incident was designated a "[[United States military nuclear incident terminology#Broken Arrow|Broken Arrow]]"—a United States military term that describes an accident involving a nuclear weapon but which does not present a risk of war.{{sfn|Natonski|2007|p=1}}{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=12}}

== Project Crested Ice ==
[[File:Thule AFB B-52 Crash Site.jpg|thumb|upright|Aerial photograph of blackened ice at the crash scene, with the point of impact at the top|alt=Aerial photograph of the crash site showing a long black mark that looks like an ink blot on white paper]]
The resulting explosion and fire destroyed many of the components that the crash scattered widely in a {{convert|1|mi|km|adj=on}} by {{convert|3|mi|km|adj=on}} area.{{sfn|McElwee|1968|p=}}{{page needed|date=June 2011}} Parts of the [[bomb bay]] were found {{convert|2|mi|km}} north of the impact area, indicating the aircraft started to break up before impact.{{sfn|Eriksson|2002|p=}}{{page needed|date=June 2011}} The ice was disrupted at the point of impact, temporarily exposing an area of seawater approximately {{convert|50|m|ft}} in diameter; ice floes in the area were scattered, upturned and displaced.{{sfn|Fristrup|1970|p=86}} South of the impact area, a {{convert|400|ft|m}} by {{convert|2200|ft|m}} blackened patch was visible where fuel from the aircraft had burned—this area was highly contaminated with [[JP-4]] aviation fuel and radioactive elements.{{sfn|Fristrup|1970|p=86}} These elements included [[plutonium]], [[uranium]], [[americium]] and [[tritium]].{{sfn|Eriksson|2002|p=28}}{{sfn|Dose Evaluation Report 2001|p=}}{{page needed|date=June 2011}} Plutonium levels as high as 380&nbsp;mg/m<sup>2</sup> were registered in the area.{{sfn|Vantine|Crites|2003}}

American and Danish officials (Greenland is a Danish territory) immediately launched "Project Crested Ice" (informally known as "Dr Freezelove"<ref group="Note">"Dr Freezelove" is an apparent [[pun|play on words]] of the 1964 film "[[Dr. Strangelove]]".</ref>{{sfn|Hanhimäki|Westad|2004|pp=300–301}}), a clean-up operation to remove the debris and contain environmental damage.{{sfn|Fristrup|1970|p=}}{{page needed|date=June 2011}} Despite the cold, dark Arctic winter, there was considerable pressure to complete the clean-up operation before the sea ice melted in the spring and deposited contaminants into the sea.{{sfn|Project Crested Ice 1969: The Thule Accident|p=50}}

A base camp (named "Camp Hunziker"{{sfn|McElwee|1968|p=}}{{page needed|date=June 2011}} after Richard Overton Hunziker, the USAF general in charge of the operation) was created at the crash site; it included a heliport, igloos, generators and communications facilities. A "zero line" delineating the {{convert|1|mi|km|adj=on}} by {{convert|3|mi|km|adj=on}} area in which [[alpha particle]] contamination could be measured was established by January&nbsp;25, four days after the crash.{{sfn|Broken Arrow 1968—Thule|p=5}} The line was subsequently used to control [[Human decontamination|decontamination]] of personnel and vehicles. An [[ice road]] was constructed to Thule from the site. This was followed by a second, more direct, road so the ice on the first road was not fatigued by overuse.{{sfn|Dresser|1970|p=26}} The camp later included a large prefabricated building, two ski-mounted buildings, several huts, a decontamination trailer and a latrine.{{sfn|Broken Arrow 1968—Thule|p=3}} These facilities allowed for 24-hour operations at the crash site.{{sfn|Broken Arrow 1968—Thule|p=3}}

Weather conditions at the site were extreme; the average temperature was {{convert|-40|C|F|0}}, at times dropping to {{convert|-60|C|F|0}}. These temperatures were accompanied by winds of up to {{convert|40|m/s|mph}}. Battery-operated instruments worked for limited periods in the cold; operators modified them to allow the battery packs to be carried under their coats to extend the batteries' lifespan.{{sfn|McElwee|1968|p=}}{{page needed|date=June 2011}} The operation was conducted without [[sunlight|natural light]] until February&nbsp;14, when sunlight gradually began appearing.{{sfn|Schwartz|1998|p=410}}{{sfn|Project Crested Ice 1970: Danish Atomic Energy Commission|p=13}}

[[File:Crested Ice Tank Loading.jpg|thumb|Contaminated ice being loaded into steel tanks at Thule during Project Crested Ice|alt=A crane shown loading contamined ice into a large steel tank.]]
The USAF worked with Danish nuclear scientists to consider the clean-up options. The resulting plan involved the removal of contaminated ice and wreckage to the United States for disposal.{{sfn|Fristrup|1970|p=90}} USAF personnel used [[grader]]s to collect the contaminated snow and ice, which was loaded into wooden boxes at the crash site. The boxes were moved to a holding area near Thule Air Base known as the "Tank Farm". There, contaminated material was loaded into steel tanks prior to being loaded onto ships.{{sfn|Dresser|1970|p=28}} Debris from the weapons was sent to the [[Pantex]] plant in [[Texas]] for evaluation,<ref name="InterimReport" /> and the tanks were shipped to [[Savannah River Site|Savannah River]] in [[South Carolina]].{{sfn|Project Crested Ice 1969: The Thule Accident|p=60}}

In 1987–88 and again in 2000, reports surfaced in the Danish press that one of the bombs had not been recovered.{{sfn|Leyne|2000}} SAC stated at the time of the incident that all four bombs were destroyed. In 2008, the BBC published an article that was based on its examination of partly declassified documents obtained some years earlier via the United States [[Freedom of Information Act]]. The documents appeared to confirm that within weeks of the accident, investigators realized only three of the weapons could be accounted for.{{sfn|Corera 2008-11-10—Mystery of lost bomb}} One of the declassified documents—dated to January 1968—details a blackened section of ice which had refrozen with [[shroud lines]] from a weapon parachute: "Speculate something melted through the ice such as burning [[Python primary|primary]] or secondary."{{sfn|Corera 2008-11-10—Mystery of lost bomb}}<ref group="Note">The "primary" and "secondary" refer to [[Teller-Ulam design|parts of the weapon]].</ref> A July 1968 report states, "An analysis by the AEC of the recovered secondary components indicates recovery of 85% of the uranium and 94%, by weight, of three secondaries. No parts of the fourth secondary have been identified."<ref>USAF Nuclear Safety, p. 4</ref>

The [[BBC]] tracked down several officials involved in the incident's aftermath. One was William H. Chambers, a former nuclear weapons designer at the [[Los Alamos National Laboratory]]. Chambers headed a team dealing with nuclear accidents, including the Thule crash. He explained the logic behind the decision to abandon the search: "There was disappointment in what you might call a failure to return all of the components&nbsp;... it would be very difficult for anyone else to recover classified pieces if we couldn’t find them."{{sfn|Corera 2008-11-10—Mystery of lost bomb}}

[[File:Mark 28 Thermonuclear Bomb.jpg|thumb|left|Set of four B28FI thermonuclear bombs of the same type as those in the accident at Thule|alt=Four silver B28FI nuclear bombs in a rack ready for loading into an aircraft.]]
In August 1968, the United States military sent a Star&nbsp;III mini-submarine to the base to look for weapon debris, especially the uranium 235 fissile core of a secondary.{{sfn|B-52 Crash at Thule Air Base 1968—USAEC|p=}}{{page needed|date=June 2011}} A much bigger operation at [[1966 Palomares B-52 crash|Palomares]] off the coast of Spain two years earlier led to the successful recovery of a lost nuclear weapon from the [[Mediterranean Sea]]; the [[B28 nuclear bomb|B28FI]] bomb was lost for 80&nbsp;days after a mid-air collision between a B-52 on a "Chrome Dome" mission and its refueling [[KC-135 Stratotanker]].<ref>USAF Nuclear Safety, 1966</ref> The purpose of the underwater search at Thule was obvious to the Danish negotiators.{{sfn|Christensen|2009|p=}}{{page needed|date=June 2011}} At lower levels, however, the dives were surrounded by some confidentiality. One document from July 1968 reads, "Fact that this operation includes search for object or missing weapon part is to be treated as [[Classified information in the United States|Confidential NOFORN]]",{{sfn|Corera 2008-11-10—Mystery of lost bomb}} meaning it was not to be disclosed to non-US nationals. It continues, "For discussion with Danes, this operation should be referred to as a survey, repeat survey of bottom under impact point."{{sfn|Corera 2008-11-10—Mystery of lost bomb}} Further indications of the search are apparent in a September 1968 interim report by the [[United States Atomic Energy Commission]], which stated, "It was further speculated that the missing ''<deleted>'', in view of its ballistic characteristics, may have come to rest beyond the observed concentration of heavy debris."{{sfn|Thule Status Report 1968|p=}}{{page needed|date=June 2011}} This discussion was a reference to the unsuccessful search for the uranium cylinder of one of the secondaries.{{sfn|Christensen|2009|p=}}{{page needed|date=June 2011}}

The underwater search was beset by technical problems and eventually abandoned. Diagrams and notes included in the declassified documents make clear it was not possible to search the entire area where crash debris had spread. Four bomb reservoirs, one nearly intact [[Teller-Ulam design|secondary]], and parts equaling two secondaries were recovered on the sea ice; parts equaling one secondary were not accounted for.<ref>USAF Nuclear Safety, 1968</ref> The search also revealed a weapon cable fairing, polar cap, and a one-foot by three-foot section of a warhead's ballistic case.{{sfn|Thule Status Report 1968|p=}}{{page needed|date=June 2011}}

The United States Air Force monitored airborne contamination through nasal swabs of onsite personnel. Of the 9,837 nasal swabs taken, 335 samples had detectable levels of alpha particle activity, although none was above acceptable levels. [[Urinalysis]] was also performed, but none of the 756 samples displayed any detectable level of plutonium.{{sfn|Dose Evaluation Report 2001|p=ES-1}}

[[File:Submersible named Star III in front of Scripps Institution of Oceanography.JPG|thumb|Star III submersible used in the underwater search|alt=Star III submersible on display outside Scripps Institution of Oceanography. The white vessel has the appearance of short, fat cigar.]]
By the time the operation concluded, 700 specialized personnel from both countries and more than 70 United States government agencies had worked for nine months to clean up the site,{{sfn|Hanhimäki|Westad|2004|pp=300–301}} often without adequate protective clothing or decontamination measures. In total, more than {{convert|550000|USgal|m3}} of contaminated liquid—along with thirty tanks of miscellaneous material, some of it contaminated—was collected at the Tank Farm.{{sfn|Thule Status Report 1968|p=}}{{page needed|date=June 2011}} Project Crested Ice ended on September&nbsp;13, 1968 when the last tank was loaded onto a ship bound for the United States.{{sfn|Eriksson|2002|p=}}{{page needed|date=June 2011}} The operation is estimated to have cost $9.4&nbsp;million (${{Formatprice|{{Inflation|US|9400000|1968|r=-4}}|0}} as of {{CURRENTISOYEAR}}).{{sfn|Schwartz|1998|p=}}{{page needed|date=June 2011}}

== Aftermath ==
=== Operation Chrome Dome ===
The incident caused controversy at the time and in the years since. It highlighted the risks Thule Air Base posed to Greenlanders from nuclear accidents and potential [[superpower]] conflicts.{{sfn|Heurlin|Rynning|2005|p=}}{{page needed|date=June 2011}} The accident, which occurred two years after the Palomares crash, signaled the immediate end of Operation Chrome Dome,{{sfn|B-52 Crash 1968—NMCC|p=}}{{page needed|date=June 2011}} which became untenable because of the political and operational risks involved.{{sfn|Lake|Styling|2004|p=19}} [[Scott Sagan]], a political science academic and writer, postulated that if the aircraft had crashed into Thule Air Base, the missile early warning system and the [[Redundancy (engineering)|redundant]] warning aircraft would have been knocked out simultaneously, potentially leading NORAD to conclude incorrectly that a nuclear attack had started.{{sfn|Edwards|Wajcman|2005|p=163}}{{sfn|Sagan|1995|pp=181–182}} In 1974, the submarine telecommunications cable between Thule and the U.S. mainland was replaced with a more reliable satellite link.<ref>{{cite journal | last = Allen | first = D. R. | year = 2006 | month = October | title = Thule Tracking Station: 40th Anniversary October 1961–2001 | publisher = United States Air Force | bibcode = 1978coss.conf..608A | pages = 608 | journal = In: Communications Satellite Systems Conference }}</ref>

According to [[Greenpeace]], the United States and U.S.S.R. were concerned enough by accidents such as the [[1961 Goldsboro B-52 crash]], the [[1966 Palomares B-52 crash]] and the Thule accident that they agreed to take measures to ensure that a future nuclear accident would not lead the other party to conclude incorrectly that a first strike was under way.{{sfn|May|1989|p=205}} Consequently, on September&nbsp;30, 1971, the two superpowers signed the "Agreement on Measures to Reduce the Risk of Nuclear War". Each party agreed to notify the other immediately in the event of an accidental, unauthorized or unexplained incident involving a nuclear weapon that could increase the risk of nuclear war.{{sfn|Goldblat|2002|pp=301–302}} They agreed to use the [[Moscow–Washington hotline]], which was upgraded at the same time, for any communications.{{sfn|Blacker|Duffy|1984}}{{sfn|Mayall|Navari|1980|pp=135–137}}

In March 2009, ''[[Time (magazine)|Time]]'' identified the Thule accident as one of the world's "worst nuclear disasters".{{sfn|Time 2009—Worst Nuclear Disasters}}

=== Weapon safety ===
Following the Palomares and Thule incidents—the only cases where the conventional explosives of U.S. nuclear bombs accidentally detonated and dispersed nuclear materials{{sfn|Global Security 2005—Broken Arrows}}—investigators concluded the HE used in nuclear weapons were not [[Chemical stability|chemically stable]] enough to withstand the forces involved in an aircraft accident. They also determined that the electrical circuits of the weapons' safety devices became unreliable in a fire and allowed connections to [[short circuit]]. The findings triggered research by scientists in the United States into safer conventional explosives and fireproof casings for nuclear weapons.{{sfn|Zukas|Walters|2002|pp=305–307}}

The [[Lawrence Livermore National Laboratory]] developed the "[[Explosives safety#Susan Test|Susan Test]]", which uses a special projectile whose design simulates an aircraft accident by squeezing and nipping explosive material between its metal surfaces.{{sfn|Zukas|Walters|2002|pp=305–307}} The test projectile is fired under controlled conditions at a hard surface to measure the reactions and thresholds of different explosives to an impact. By 1979, the [[Los Alamos National Laboratory]] developed a new, safer type of explosive, called [[Insensitive munitions#Insensitive high explosives|insensitive high explosive]] (IHE), for use in U.S. nuclear weapons;{{sfn|Plummer|Greenwood|1998|p=}}{{page needed|date=June 2011}}{{sfn|Busch|2004|pp=50–51}} the physicist and nuclear weapons designer [[Ray Kidder]] speculated that the weapons in the Palomares and Thule accidents would probably not have detonated had IHE been available at the time.{{sfn|Kidder|1991|p=32}}

=== Thulegate ===
Denmark's nuclear-free zone policy originated in 1957, when the coalition government decided in the lead-up to the [[1957 Paris summit|Paris NATO summit]] not to stockpile nuclear weapons on its soil in peacetime.{{sfn|Ørvik|1986|p=205}}{{sfn|Agger|Wolsgård}} The presence of the bomber in Greenland airspace in 1968 therefore triggered public suspicions and accusations that the policy was being violated.{{sfn|Kristensen|2004}}{{sfn|Jones|1986|p=176}}{{sfn|Kristensen|1999}} The nature of the "Hard Head" missions was suppressed at the time of the accident;<ref>US State Department (via Nautilus.org), 1968</ref> the Danish and American governments claimed the bomber was not on a routine mission over Greenland and that it diverted there because of a one-off emergency.{{sfn|Kristensen|1999}}{{sfn|Taagholt|Hansen|2001|pp=42–43}} US documents declassified in the 1990s contradicted this view, and resulted in a 1995 Danish political scandal known as "Thulegate".{{sfn|Kristensen|1999}}

The Danish parliament commissioned a report from the Danish Institute of International Affairs (DUPI)<ref group="Note">''Dansk Udenrigspolitisk Institut.''</ref> to determine the history of U.S. nuclear overflights of Greenland and the role of Thule Air Base in this regard. When the two-volume work was published on January&nbsp;17, 1997{{sfn|DUPI 1997}} it confirmed that the nuclear-armed flights over Greenland were recurrent but that the United States had acted in good faith. The report blamed Danish Prime Minister [[H. C. Hansen]] for introducing ambiguity in the Danish–U.S. security agreement: he was not asked about, nor did he mention, the official Danish nuclear policy when meeting with the United States ambassador in 1957 to discuss Thule Air Base. Hansen followed up the discussion with an infamous letter pointing out that the issue of "supplies of munition of a special kind" was not raised during the discussion, but that he had nothing further to add.{{sfn|Hansen|1957}} In doing so, the report concluded, he tacitly gave the United States the go-ahead to store nuclear weapons at Thule.{{sfn|Brooke|2000}}

The report also confirmed that the U.S. stockpiled nuclear weapons in Greenland until 1965, contradicting assurances by Danish foreign minister [[Niels Helveg Petersen]] that the weapons were in Greenland's airspace, but never on the ground.{{sfn|Kristensen|1999}}{{sfn|Brooke|2000}} The DUPI report also revealed details of [[Project Iceworm]], a hitherto secret [[United States Army]] plan to store up to 600 nuclear missiles under the [[Greenland ice sheet|Greenland ice cap]].{{sfn|Taagholt|Hansen|2001|p=40}}

=== Workers' compensation claims ===
[[File:ThuleRadiationCheck.jpg|thumb|upright|A monitor checks a pump operator for radiation contamination during Project Crested Ice|alt=A worker stands and waits while a colleague scans him for signs of radioactivity. Steel tanks with "Crested Ice" painted on them are visible in the background]]
Danish workers involved in the clean-up operation claimed long-term health problems resulted from their exposure to the radiation. Although they did not work at Camp Hunziker, the Danes worked at the Tank Farm where the contaminated ice was collected, in the port where the contaminated debris was shipped from, and they also serviced the vehicles used in the clean-up.{{sfn|Juel|Engholm|Storm|2005|p=5}} It is also possible that they were exposed to radiation in the local atmosphere.{{sfn|Juel|Engholm|Storm|2005|p=5}} Many of the workers surveyed in the years following Project Crested Ice reported health problems. A 1995 survey found 410 deaths by cancers out of a sample of 1,500 workers.{{sfn|Juel|Engholm|Storm|2005|p=15}}

In 1986, Danish Prime Minister [[Poul Schlüter]] commissioned a radiological examination of the surviving workers. The Danish Institute for Clinical [[Epidemiology]] concluded 11 months later that cancer incidents were 40&nbsp;percent higher in Project Crested Ice workers than in workers who had visited the base before and after the operation. The Institute of Cancer Epidemiology found a 50&nbsp;percent higher cancer rate in the workers than in the general population, but concluded radiation exposure was not to blame.{{sfn|Schwartz|1998|p=411}}

In 1987, almost 200 former cleanup workers took legal action against the United States. The action was unsuccessful, but resulted in the release of hundreds of classified documents. The documents revealed that USAF personnel involved in the clean-up were not subsequently monitored for health problems, despite the likelihood of greater exposure to radiation than the Danes.{{sfn|Schwartz|1998|p=411}} The United States has since instigated regular examinations of its workers.{{sfn|Mulvey|2007}} In 1995, the Danish government paid 1,700 workers compensation of 50,000&nbsp;[[Danish krone|kroner]] each{{sfn|Juel|Engholm|Storm|2005|p=11}} ({{Formatnum:{{Inflation|DE|50000|1995|r=-4}}}} kroner as of {{CURRENTISOYEAR}}).

Danish workers' health has not been regularly monitored, despite a [[European Court of Justice|European Court]] directive to the Danish government to begin examinations in the year 2000,{{sfn|Corera 2008-11-10—Legacy of lost bomb}} and a May 2007 [[European Parliament]] resolution instructing the same.{{sfn|Mulvey|2007}}<ref>European Parliament, 2007</ref> In 2008, the Association of Former Thule Workers took the case to the European courts. The petitioners claimed that Denmark's failure to comply with the rulings led to delays in detecting their illnesses, resulting in worsened prognoses. The country joined the [[European Atomic Energy Community]] in 1973, and is therefore not legally bound by the European treaty with respect to events in 1968: "When the accident occurred, Denmark was not a Member State and could not therefore be considered as being bound by the Community legislation applicable at that time. The obligations of Denmark towards the workers and the population likely to be affected by the accident could only flow from national legislation."<ref>European Parliament, 2004</ref>

The Danish government rejected a link between the accident and long-term health issues. Dr. Kaare Ulbak of the Danish National Institute of Radiation Protection said, "We have very good registers for cancer incidents and cancer mortality and we have made a very thorough investigation."{{sfn|Corera 2008-11-10—Legacy of lost bomb}} The workers said the lack of proof was attributable to the lack of appropriate medical monitoring. As of November 2008, the case has been unsuccessful.{{sfn|Corera 2008-11-10—Legacy of lost bomb}}

=== Scientific studies ===
[[Radiation contamination]] occurred particularly in the marine environment, which the local [[Inughuit]] rely upon as a food source. The fission material in the weapons consisted mostly of [[Uranium 235]] (about 4 times the mass of [[Plutonium 239]]), while the radioactive debris consists of at least two different "source terms".<ref group="Note">The "source term" is the measure of radioactive contamination released during an accident.</ref> Scientific monitoring of the site has been carried out periodically, with expeditions in 1968, 1970, 1974, 1979, 1984, 1991, 1997 and 2003.{{sfn|Eriksson|2002|p=15}}{{sfn|Nielsen|Roos|2006|p=}}{{page needed|date=June 2011}}

A 1997 international expedition of mainly Danish and Finnish scientists carried out a comprehensive sediment sampling program in North Star Bay.{{sfn|Eriksson|2002|p=13}} The main conclusions were: plutonium has not moved from the contaminated sediments into the surface water in the shelf sea; the debris has been buried to a great depth in the sediment as a result of biological activity; transfer of plutonium to [[benthic zone|benthic]] biota is low. Other research indicates that uranium is [[Leaching (chemical science)|leaching]] from the contaminated particles faster than plutonium and americium.{{sfn|Eriksson|2002|p=2}} Research conducted in 2003 concluded, "Plutonium in the marine environment at Thule presents an insignificant risk to man. Most plutonium remains in the seabed under Bylot Sound far from man under relatively stable conditions and concentrations of plutonium in seawater and animals are low. However, the plutonium contamination of surface soil at [[Narsaarsuk]] could constitute a small risk to humans visiting the location if radioactive particles are resuspended in the air so that they might be inhaled."{{sfn|Nielsen|Roos|2006|p=}}{{page needed|date=June 2011}}{{sfn|Nielsen|Roos|Dahlgaard|Olsen|2009|p=}}{{page needed|date=June 2011}} In 2003, 2007 and 2008, the first samples were taken on land by the [[Risø DTU National Laboratory for Sustainable Energy|Risø National Laboratory]]—the findings were due to be published in 2009.{{sfn|Ritzau 2008-11-13}}{{sfn|Nielsen|2008|p=}}{{page needed|date=June 2011}}{{sfn|IAEC: Thule 2007}}{{page needed|date=June 2011}}

=== Review of evidence of missing bomb ===
The Danish foreign ministry reviewed the 348&nbsp;documents that the BBC obtained in 2001 under the Freedom of Information Act. In January 2009, foreign minister [[Per Stig Møller]] commissioned a study by the Danish Institute for International Studies (DIIS) to compare the 348 documents with 317 documents released by the Department of Energy in 1994 in order to determine if the 348 documents contained any new information about an intact nuclear weapon at Thule.{{sfn|Kromann|2009}} In August 2009, DIIS published its report, which refuted the assertions of the BBC.{{sfn|Christensen|2009|p=}}{{page needed|date=June 2011}} The report concluded that there was no missing bomb, and that the American underwater operation was a search for the [[uranium-235]] of the fissile core of a secondary. For the first time, the report was able to present an estimate of the amount of plutonium contained in the [[plutonium pit|pits]] of the primaries.{{sfn|Christensen|2009|p=}}{{page needed|date=June 2011}}<ref>{{cite news | url = http://nyhederne.tv2.dk/article.php/id-24104886.html | date = 2009-07-31 | accessdate = 2009-08-04 | title = Greenland Atomic Bomb a Hoax | publisher = [[Ritzau]] via [[TV 2 (Denmark)]] | archiveurl = http://www.webcitation.org/5ioX6caDk | archivedate = 2009-08-05 | deadurl = no }} {{da icon | archiveurl = http://www.webcitation.org/5ioX6caDk | archivedate = 2009-08-05 | deadurl = no }}</ref>

==See also==
{{Portal|United States Air Force}}
* [[List of military nuclear accidents]]

== Notes ==
{{reflist|group="Note"}}

== Footnotes ==
{{reflist|colwidth=30em}}

== References ==
{{refbegin}}

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* {{cite book
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* {{cite book
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* {{cite book
  | title = Project Crested Ice: A joint Danish-American report on the crash near Thule Air Base on 21 January 1968 of a B-52 bomber carrying nuclear weapons
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  | month = February
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=== Journals and reports ===
* {{cite book
  | title = International Peer Review of the Technical Contentof the Project Proposal 'Thule 2007 - Investigation of Radioactive Contamination on Land'
  | date = 2008-03-03
  | publisher = International Atomic Energy Commission
  | location = Vienna
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  | url = http://www.thulesundhed.dk/Webnodes/download/264
  | archiveurl = http://www.webcitation.org/5k42G3ocG <!-- it's a pdf but wo/".pdf" ;) -->
  | archivedate = 2009-09-25
  | ref = {{harvid|IAEC: Thule 2007}}
  }}
* {{cite journal
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  | month = January
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  | url = http://www.risoe.dk/rispubl/NUK/nukpdf/ris-r-213_p79-88.pdf
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* [http://www.thulesagen.dk/thuledoc/0106883.pdf ''AEC Observers' Interim Report of Thule Accident''], United States Atomic Energy Commission, 1968-02-26, Report, retrieved on 2008-11-13
* {{cite journal
  | title = Broken Arrow&nbsp;— Palomares, Spain
  | year = 1966
  | month = Sep-Oct
  | journal = USAF Nuclear Safety
  | volume = 52
  | publisher = Directorate of Nuclear Safety, United States Air Force
  | url = http://www.dod.mil/pubs/foi/reading_room/133.pdf
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* {{cite journal
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* {{cite journal
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* {{cite journal
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* {{cite journal
  | title = SAC's Deadly Daily Dozen
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* {{cite web
  | title = Thule Status Report
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* {{cite journal
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=== Online sources ===
* {{cite web
  | last = Agger
  | first = Jonathan Søborg
  | last2 = Wolsgård
  | first2 = Lasse
  | title = A Policy of the Utmost Flexibility: Danish Nuclear Weapons Policy 1956–1960
  | publisher = Danish Historical Association
  | work = historisktidsskrift.dk
  | url = http://www.historisktidsskrift.dk/summary/101_109.html
  | accessdate = 2009-05-10
  | ref = harv
  }}
* {{cite web
  | title = B-52 Crash
  | date = 1968-01-24
  | publisher = [[National Military Command Center]] via Nautilus.org
  | location = Pentagon
  | url = http://www.nautilus.org/archives/library/security/foia/Denmark/State012368.PDF
  | format = pdf
  | accessdate = 2009-04-12
  | archiveurl = http://wayback.archive.org/web/*/http://www.nautilus.org/archives/library/security/foia/Denmark/State012368.PDF
  | archivedate = 2008-11-20
  | ref = {{harvid|B-52 Crash 1968—NMCC}}
  }} {{dead link|date=September 2010|bot=H3llBot}}<!-- wayback machine is having problemes, too -->
* {{cite web
  | title = B-52 Crash at Thule Air Base
  | date = 1968-01-22
  | publisher = [[United States Atomic Energy Commission]]
  | url = http://web.archive.org/web/20110725214623/http://www.thulesagen.dk/thuledoc/0075943.pdf
  | format = pdf
  | accessdate = 2008-11-13
  | ref = {{harvid|B-52 Crash at Thule Air Base 1968—USAEC}}
  }}
* {{cite news
  | last = Brooke
  | first = James
  | date = 2000-09-18
  | title = Greenlanders Wary of a New Role in U.S. Defenses
  | publisher = [[New York Times]]
  | url = http://wayback.archive.org/web/*/http://cndyorks.gn.apc.org/yspace/articles/greenland3.htm
  | accessdate = 2008-11-11
  | ref = harv
  }}
* {{cite news
  | last = Corera
  | first = Gordon
  | authorlink = Gordon Corera
  | title = Radioactive legacy of 'lost bomb'
  | date = 2008-11-10
  | publisher = BBC News
  | url = http://news.bbc.co.uk/2/hi/science/nature/7720466.stm
  | accessdate = 2011-06-17
  | ref = {{harvid|Corera 2008-11-10—Legacy of lost bomb}}
  }}
* {{cite news
  | last = Corera
  | first = Gordon
  | authorlink = Gordon Corera
  | date = 2008-11-10
  | title = Mystery of lost US nuclear bomb
  | publisher = BBC News
  | url = http://news.bbc.co.uk/2/hi/europe/7720049.stm
  | accessdate = 2011-06-17
  | ref = {{harvid|Corera 2008-11-10—Mystery of lost bomb}}
  }}
* {{cite web
  | title = Foreign Relations of the United States 1964–1968, Volume XII, Western Europe: Denmark
  | publisher = [[United States Department of State]]
  | url = http://history.state.gov/historicaldocuments/frus1964-68v12/ch1
  | accessdate = 2008-11-12
  | ref = {{harvid|Foreign Relations of the United States 1964–1968: Denmark}}
  }} 
* {{cite web
  | title = Broken Arrows
  | date = 2005-04-28
  | publisher = [[GlobalSecurity.org]]
  | url = http://www.globalsecurity.org/wmd/ops/broken-arrow.htm
  | accessdate = 2011-06-17
  | ref = {{harvid|Global Security 2005—Broken Arrows}}
  }}
* {{cite web
  | last = Hansen
  | first = H. C.
  | authorlink = H. C. Hansen
  | date = 1957-11-16
  | title = Danish Prime Minister Gives Tacit Go-Ahead For U.S. Nuclear Weapons In Greenland
  | publisher = The Nautilius Institute
  | url = http://wayback.archive.org/web/*/http://www.nautilus.org/archives/library/security/foia/DKhansen57.html
  | accessdate = 2009-03-20
  | archiveurl = http://web.archive.org/web/20071106145717/http://www.nautilus.org/archives/library/security/foia/DKhansen57.html
  | archivedate = 2007-11-06
  | ref = harv
  }}
* {{cite web
  | last = Kristensen
  | first = Hans M.
  | year = 2004
  | title = Denmark's Thulegate
  | publisher = [http://www.nukestrat.com/ The Nuclear Information Project]
  | url = http://www.nukestrat.com/dk/gr.htm
  | accessdate = 2009-04-21
  | ref = harv
  }}
* {{cite web
  | last = Kristensen
  | first = Hans M.
  | date = 1999-10-20
  | title = Secrecy On A Sliding Scale: U.S. Nuclear Weapons Deployments And Danish Non-Nuclear Policy
  | publisher = The Nautilius Institute
  | url = http://wayback.archive.org/web/*/http://www.nautilus.org/archives/nukepolicy/Denmark/index.html
  | accessdate = 2009-03-20
  | archiveurl = http://web.archive.org/web/20071231130921/http://www.nautilus.org/archives/nukepolicy/Denmark/index.html
  | archivedate = December 31, 2007
  | ref = harv
  }}
* {{cite web
  | last = Kristensen
  | first = Hans M.
  | date = 1968-01-23
  | title = Following Bomber Crash, U.S. Copenhagen Embassy Urges State Department To Lie About Flight Route
  | publisher = US State Department via Nautilus.org
  | url = http://wayback.archive.org/web/*/http://www.nautilus.org/archives/library/security/foia/White012368.html
  | accessdate = 2009-04-13
  | archiveurl = http://www.webcitation.org/5gX4OhRjl
  | archivedate = 2009-05-04
  | ref = harv
  }}
* {{cite news
  | last = Kromann
  | first = Hans Christian
  | date = 2009-01-07
  | title = Arctic atomic bomb should be examined again
  | work = politiken.dk
  | newspaper = [[Politiken]]
  | url = http://politiken.dk/politik/ECE624896/arktisk-atombombe-skal-undersoeges-igen/
  | accessdate = 2011-06-17
  | ref = harv
  }}
* {{cite news
  | last = Leyne
  | first = Jon
  | date = 2000-08-13
  | title = Nuclear bomb 'lost near Greenland'
  | publisher = BBC News
  | url = http://news.bbc.co.uk/2/hi/americas/878907.stm
  | accessdate = 2011-06-16
  | ref = harv
  }}
* {{cite web
  | last = May
  | first = John
  | year = 1989
  | title = The Greenpeace book of the nuclear age; The hidden history - the human cost
  | page = 205
  | publisher = [[Greenpeace]] Books
  | url = http://www.greenpeace.org/raw/content/international/press/reports/the-greenpeace-book-of-the-nuc.pdf
  | accessdate = 2009-04-19
  | archiveurl = http://www.webcitation.org/5gX4Pvpv6
  | archivedate = 2009-05-04
  | ref = harv
  }}
* {{cite web
  | last = McElwee
  | first = Captain Robert E.
  | year = 1968
  | month = March
  | title = Project Crested Ice
  | publisher = United States Navy
  | url = http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA283578&Location=U2&doc=GetTRDoc.pdf
  | format = pdf
  | accessdate = 2008-11-14
  | ref = harv
  }}
* {{cite news
  | last = Mulvey
  | first = Stephen
  | date = 2007-05-11
  | title = Denmark challenged over B52 crash
  | publisher = [[BBC News]]
  | url = http://news.bbc.co.uk/2/hi/europe/6647421.stm
  | accessdate = 2011-06-16
  | ref = harv
  }}
* {{cite news
  | agency = [[Ritzau]]
  | title = Risø examine radiation at the Thule base
  | date = 2008-11-13
  | url = http://politiken.dk/indland/article597710.ece
  | accessdate = 2011-06-17
  | language = Danish
  | ref = {{harvid|Ritzau 2008-11-13}}
  }}
* [http://www.europarl.europa.eu/meetdocs/2004_2009/documents/cm/530/530757/530757en.pdf ''Petition 720/2002 by Jeffrey Carswell''], Committee on Petitions, European Parliament, 2004
* [http://www.europarl.europa.eu/meetdocs/2004_2009/documents/cm/650/650924/650924en.pdf ''Petition 720/2002 by Jeffrey Carswell''], Committee on Petitions, European Parliament, 2007
* {{cite web
  | last = Plummer
  | first = David W.
  | last2 = Greenwood
  | first2 = William H.
  | year = 1998
  | month = June
  | title = The History of Nuclear Weapon Safety Devices
  | publisher = Sandia National Laboratories
  | location = Albuquerque
  | url = http://www.osti.gov/bridge/servlets/purl/671923-JYRvMV/webviewable/671923.pdf
  | ref = harv
  }}
* {{cite web
  | title = Project Crested Ice: The Thule Accident
  | date = 1969-04-23
  | publisher = History & Research Division, Strategic Air Command (via [[National Security Archive]])
  | url = http://www.gwu.edu/~nsarchiv/nukevault/ebb267/03.pdf
  | accessdate = 2011-06-17
  | archiveurl = http://www.webcitation.org/5gX4OJXVL
  | archivedate = 2009-05-04
  | ref = {{harvid|Project Crested Ice 1969: The Thule Accident}}
  }}
* {{cite web
  | last = Taagholt
  | first = Jørgen
  | last2 = Hansen
  | first2 = Jens Claus
  | coauthors = Daniel Lufkin (translator)
  | year = 2001
  | title = Greenland: Security Perspectives
  | pages = 35–43
  | publisher = Arctic Research Consortium of the United States
  | location = Fairbanks, Alaska
  | url = http://www.arcus.org/publications/downloads/greenland.pdf
  | archiveurl = http://www.webcitation.org/5gX4V94NK
  | archivedate = 2009-05-04
  | ref = harv
  }}
* {{cite web
  | title = Thule Nuclear Weapons Accident: Dose Evaluation Report
  | publisher = [[United States Air Force Medical Service]]
  | year = 2001
  | month = April
  | url = http://airforcemedicine.afms.mil/latestnews/body.pdf
  | accessdate = 2011-06-17
  | format = pdf
  | ref = {{harvid|Dose Evaluation Report 2001}}
  }}
* {{cite web
  | last = Vantine
  | first = Harry C.
  | last2 = Crites
  | first2 = Thomas R.
  | date = 2003-03-26
  | title = Relevance of Nuclear Weapons Clean-up Experience to Dirty Bomb Response
  | publisher = [[Lawrence Livermore National Laboratory]]
  | url = http://wayback.archive.org/web/*/https://eed.llnl.gov/ans/2002/vantine/vantine_ans_2002.pdf
  | format = pdf
  | ref = harv
  }}
{{refend}}

== Further reading ==
* {{cite book
  | last = Brink
  | first = Poul
  | year = 1997
  | title = Thule-Sagen, Løgnens Univers
  | language = Danish
  | publisher = Aschehoug
  | isbn = 87-11-15045-9
  | url = http://books.google.com/books?id=VYI3AAAACAAJ
  | ref = harv
  }}
* {{cite book
  | last = Oskins
  | first = James C.
  | last2 = Maggelet
  | first2 = Michael H.
  | year = 2008
  | title = Broken Arrow&nbsp;— The Declassified History of U.S. Nuclear Weapons Accidents
  | publisher = [[Lulu (company)|Lulu]]
  | isbn = 1-4357-0361-8
  | url = http://books.google.com/?id=gi7HARO8vTcC
  | accessdate = 2011-06-17
  }}

== External links ==
{{Commons category|Thule accident}}
* [http://www.thulesagen.dk/news.php Documentation and photos] {{da icon}}
* [http://www.afrri.usuhs.mil/outreach/reports/pdf/SP86-2.pdf DoD Mishaps] by the [[Armed Forces Radiobiology Research Institute]]
* [http://news.bbc.co.uk/2/hi/7720671.stm Declassified US government video of clean-up operation] BBC
* [http://www.sis.dk/ National Institute for Radiation Protection (Denmark)] {{da icon}}

{{Featured article}}

{{Aviation accidents and incidents in 1968}}

{{DEFAULTSORT:Thule Air Base B-52 crash}}
[[Category:1968 in Greenland]]
[[Category:1995 in Denmark]]
[[Category:Accidents and incidents involving the Boeing B-52 Stratofortress]]
[[Category:Accidents and incidents involving United States Air Force aircraft]]
[[Category:Aviation accidents and incidents in 1968]]
[[Category:Aviation accidents and incidents in Greenland]]
[[Category:Cold War military history of the United States]]
[[Category:Aviation accidents and incidents involving nuclear weapons]]
[[Category:Military in the Arctic]]
[[Category:Political scandals in Denmark]]
[[Category:Aircraft fires]]
[[Category:Denmark–United States relations]]
[[Category:1968 in military history]]
[[Category:1968 in the United States]]
[[Category:1968 in Denmark]]

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