In 1950, an American B-36 dropped an unarmed nuclear bomb off the coast of British Columbia, marking the first “Broken Arrow” incident.
On February 13, 1950, a US Air Force B-36 Peacemaker bomber experienced mechanical problems during a training flight. To lighten the load, the crew dropped an unarmed Mark 4 nuclear bomb over the Pacific Ocean near the Canadian coast. This event became known as the first “Broken Arrow” incident, a term used to describe accidents involving nuclear weapons. Although the bomb did not cause a nuclear explosion, the incident highlights the risks associated with handling and transporting such weapons.
Background to the flight and mission of the B-36 Peacemaker
On February 13, 1950, a US Air Force Convair B-36B Peacemaker bomber, registration 44-92075, took off from Eielson Air Force Base near Fairbanks, Alaska. The aircraft belongs to the 7th Heavy Bombardment Squadron, and is carrying out a training mission simulating a nuclear attack on San Francisco, before returning to its base in Carswell, Texas. The B-36B, America’s first true intercontinental bomber, is designed to carry nuclear warheads over long distances, with a range of over 6,000 kilometers. On this mission, the aircraft carried a Mark 4 nuclear bomb, an improved version of the “Fat Man” bomb dropped on Nagasaki in 1945. The Mark 4 is approximately 3.25 meters long, 1.5 meters in diameter and weighs almost 4,900 kilograms. However, in accordance with the safety protocols of the time, the bomb was fitted with a dummy lead core, making a nuclear explosion impossible.
Mechanical problems in flight
About six hours into the flight, the B-36 encountered unfavorable weather conditions, with an accumulation of ice on the aircraft’s surfaces. To maintain cruising altitude at 3,600 meters, the crew increased the power of the six Pratt & Whitney R-4360 Wasp Major radial engines. Unfortunately, three of them caught fire and had to be shut down, considerably reducing the power available. With only three engines operational, the aircraft is losing altitude at a rate of over 150 metres per minute. The crew attempt to stabilize the aircraft, but the situation becomes critical. At an altitude of around 2,400 meters, the captain, Captain Harold Barry, decided to change course and fly over the Pacific Ocean, thus minimizing the risk of a crash.
Dropping the Mark 4 bomb
In accordance with US Air Force safety procedures, the crew prepares the bomb for emergency release. Although devoid of its nuclear core, the Mark 4 contains several tons of conventional explosives. Captain Barry orders the detonator to be set to explode at an altitude of around 1,400 meters, guaranteeing the bomb’s destruction without risk to civilians. At an altitude of 2,700 metres, some 88 kilometers northwest of Bella Bella, British Columbia, the bomb was dropped. Moments later, a luminous explosion is observed, resulting from the detonation of conventional explosives. The explosion did not cause a nuclear reaction, confirming the absence of fissile material in the bomb.
Crew evacuation and aircraft crash
After the bomb was dropped, the aircraft’s situation continued to deteriorate. At an altitude of around 1,500 meters, Captain Barry ordered the crew to parachute out. The 17 crew members abandoned the aircraft over Princess Royal Island. Twelve were found safe and sound, although one was injured. Sadly, five crew members were never found, having probably fallen overboard in icy waters where survival is limited without appropriate equipment. As for the B-36, it continued its flight without a pilot and finally crashed on the side of Mount Kologet, some 350 kilometers north of the evacuation zone. The crash site was not discovered until 1953, during a separate search mission by the Royal Canadian Air Force.
Consequences and historical context
This incident marked the first event classified as a “Broken Arrow”, a term used by the U.S. military to designate accidents involving nuclear weapons that do not present a risk of nuclear war. Between 1950 and 1980, at least 32 such incidents were officially recognized by the U.S. Department of Defense. At the time of the 1950 incident, the United States possessed some 235 operational atomic bombs, while the Soviet Union had just two. This numerical advantage contributed to America’s nuclear deterrence strategy in the early years of the Cold War. However, incidents such as the B-36 highlighted the dangers inherent in transporting and handling nuclear weapons, leading to revisions of safety protocols and operational procedures to minimize future risks.
Subsequent nuclear incidents and lessons learned
The B-36 incident in 1950 marked the start of a series of accidents involving nuclear weapons within the US military. Between 1950 and 1980, at least 32 “Broken Arrow” incidents were officially recorded, involving the loss, damage or inadvertent release of nuclear bombs. While most of these events did not result in a nuclear explosion, some had serious consequences, including radioactive contamination of certain areas.
Examples of similar incidents
- 1958 – Tybee Island, Georgia: A B-47 bomber collides with an F-86 fighter. The crew dropped a Mark 15 nuclear bomb into the Atlantic Ocean off the coast of Georgia. It was never recovered.
- 1966 – Palomares, Spain: During an air-to-air refueling mission, a B-52 collides with a KC-135 tanker, dropping four B28 nuclear bombs on Spanish soil. Two bombs partially explode, dispersing radioactive plutonium.
- 1968 – Greenland, Thule base: a B-52 crashes with four nuclear bombs. Although the warheads do not explode, radioactive contamination affects the local environment.
Consequences for nuclear doctrine
These incidents led to major changes in US nuclear doctrine and nuclear weapons management procedures. From the 1960s onwards, the Operation Chrome Dome program required armed bombers to patrol the air permanently, but after several incidents, this practice was discontinued in 1968. Other measures were adopted to reduce risks:
- Secure storage of nuclear weapons: warheads and their fissile cores are kept separate until activated by presidential order.
- Reinforced safety mechanisms: New devices prevent the accidental detonation of a bomb in the event of inadvertent release.
- Fewer flights with nuclear weapons: From the 1970s onwards, bombers no longer carried nuclear weapons in flight at all times, except for specific exercises.
Strategic impact of the incident on the Cold War
At the time of the first Broken Arrow incident, the Cold War was escalating. In 1950, the United States had around 235 nuclear bombs, while the Soviet Union had less than five. The loss of a bomb, even without fissile material, remains a strategic concern, not least because of the risk of espionage or acquisition by an enemy country.
Geopolitical implications
- Deterrence and propaganda: the Soviet Union exploited these incidents to criticize the reliability and safety of American nuclear weapons.
- Increased nuclear tensions: the arms race led the USA and the USSR to strengthen their strike capabilities and the protection of their arsenals.
- Bomber improvement programs: The incident highlights the weaknesses of the B-36, in particular its unreliable piston engines. It accelerated the adoption of the faster, more robust B-52 Stratofortress.
Recovery and investigation at the crash site
The site of the B-36 crash was not discovered until 1953, three years after the incident, by a Canadian search plane. The American government feared that sensitive parts of the aircraft might fall into the wrong hands. A recovery mission was organized, followed by a destruction operation in 1954 to remove classified components.
- Destruction of sensitive parts: Explosive teams neutralized the bomber’s critical equipment.
- Recovery of certain parts: Some electronic components and engines were recovered for analysis.
- Environmental risk assessment: The absence of a nuclear core in the dropped bomb reduces the risk of radioactive contamination.
Subsequent investigations and site visits
Since the discovery of the site, several expeditions have been carried out by investigators and historians. In 2003, an investigation team confirmed that the main remaining debris was the aft crew compartment, part of the canopy and the aft bomb bay. Visitors and collectors of military artefacts have since recovered fragments of the aircraft.
The B-36 incident in 1950 is a reminder of the risks involved in transporting and managing nuclear weapons. It played a major role in the evolution of nuclear safety protocols, prompting the US military to review its practices and reinforce the safety of its operations. Although no Broken Arrow-type incidents have been reported since 1980, the technological and human risks associated with nuclear weapons remain a major strategic challenge.
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