1950 British Columbia B-36 crash

On 13 February 1950, a Convair B-36B, serial number 44-92075 assigned to the 7th Bomb Wing at Carswell Air Force Base, crashed in northern British Columbia after jettisoning a Mark 4 nuclear bomb. This was the first such nuclear weapon loss in history. The B-36 had been en route from Eielson Air Force Base near Fairbanks, Alaska to Carswell AFB in Fort Worth, Texas, on a mission that included a simulated nuclear attack on San Francisco.

Incident
Convair 44-92075 was on a mission that was part of the first full-scale practice nuclear strike against the Soviet Union. Each B-36 involved in this exercise was to conduct a simulated nuclear attack on an American city. The exercise was also intended to test whether the B-36 could attack the Soviet Union during the Arctic winter, when temperatures are so low that if a plane engine were shut down while a plane being serviced on the ground, the engine could not be restarted.

Plane 44-92075 took off from Eielson AFB with a crew of 16 plus one observer. The plan for the 24-hour flight was to fly over the North Pacific, due west of the Alaska panhandle and British Columbia, then head inland over Washington state and Montana. The flight plan did not include any penetration of Canadian airspace. The plane carried a Mark IV atomic bomb, containing a substantial quantity of natural uranium and 5000 pounds of conventional explosives. According to the USAF, the bomb did not contain the plutonium core necessary for a nuclear detonation.

Cold weather (-40 F on the ground at Eielson AFB) adversely affected the planes involved in this exercise, and some minor difficulties with 44-92075 were noted before takeoff. Seven hours into the flight, three of the six engines began shooting flames and were shut down, and the other three engines proved incapable of delivering full power. The subsequent investigation blamed ice buildup in the mixture control air intakes.

The crew decided to abandon the aircraft because it could not stay aloft with three engines out of commission while carrying a heavy payload. The atomic bomb was jettisoned and detonated in mid-air, resulting in a large conventional explosion over the Pacific. The USAF later stated that the fake practice core on board the aircraft was inserted into the weapon before it was dropped.

The aircraft commander steered the plane over Princess Royal Island to spare his crew having to parachute into the cold North Pacific, whereupon the crew bailed out. Before bailing out last, he set a turning course toward the open ocean using the autopilot.

The plane had been in constant radio contact with the Strategic Air Command and within minutes of the bailout the Royal Canadian Air Force launched Operation Brix to find the missing men. Poor weather hampered search efforts; nevertheless 12 of the 17 men were eventually found alive. The five deceased airmen were believed to have bailed out of the aircraft earlier than the surviving crew members, and it was assumed that they landed in the ocean and drowned. Canadian authorities were never told that the aircraft was carrying a nuclear weapon.

Subsequent events
Search planes were pulled off the search for a C-54 that had disappeared three weeks earlier, to search for the B-36.

A more exhaustive search was not launched for the plane as it was believed to be at the bottom of the Pacific. Three years later, however, a RCAF flight searching for the missing de Havilland Dove aircraft of Texas millionaire oilman Ellis Hall spotted the B-36's wreckage. It was nearly completely intact, on the side of Mount Kologet, about 50 mi from the Alaskan border, roughly due east of the towns of Stewart, BC and Hyder, AK, on the east side of the isolated Nass Basin northwest of Hazelton, British Columbia.

The USAF immediately began an investigation. A team was sent in September 1953 but the effort was not given a high priority. After 19 days of trudging through the wilderness, they failed to reach the site. The effort was resumed the following year with better equipment, and in August 1954 a new team of USAF personnel accompanied by a local guide reached the wreckage. They recovered important components and then used explosives to destroy what was visible above the snow. The American and Canadian military kept the location of the wreck secret, though the operation had been run openly and the general details were known to the public. Curiously, when the American military first released information about the crash decades later, the documents falsely stated that the wreck had been found on distant Vancouver Island – possibly because 10 survivors picked up by the 'Cape Perry' had been taken to Port Hardy and a photograph of them taken there.

In 1956, two civilian surveyors chanced on the wreck and noted its exact location, which otherwise remained unknown for the next 40 years. In 1997 one of the surveyors provided the coordinates to two distinct expeditions, one American and one led by the Canadian Department of National Defence, seeking to conduct an environmental analysis of the site. Both expeditions reached the wreck around the same time, and members were apparently the first humans to set foot in the area since 1956. These environmental missions found no unusual radiation levels, and led to the crash location becoming public knowledge. Local salvage efforts began, with many items going to local museums. In late 1998, the Canadian government declared the site protected.