Air India Flight 182, an Air India flight operating on the Montreal, Canada–London, U.K.–Delhi, India route, is destroyed by a bomb on June 23, 1985, at an altitude of 31,000 feet and crashes into the Atlantic Ocean while in Irish airspace.

It is the first bombing of a 747 jumbo jetliner. A total of 329 people are killed, including 268 Canadian citizens, 27 Britons, and 24 Indians. The majority of the victims were Canadian citizens of Indian ancestry. The incident is the largest mass murder in Canadian history. It is the deadliest terrorist attack involving an airplane until the September 11, 2001, attacks in the United States in 2001. The bombing of Air India 182 occurs at the same time as the Narita Airport bombing in Japan. Investigators believe that the two plots are linked, and that those responsible are aiming for a double bombing. However, the bomb at Narita explodes before it can be loaded onto a plane.

At 07:14:01 GMT, the crew of Air India 182 “squawked 2005,” a routine activation of its aviation transponder, as requested by Shannon International Airport Air Traffic Control (ATC). The plane then disappears from radar. A bomb in a Sanyo tuner in a suitcase in the forward cargo hold explodes while the plane is at 31,000 feet at 51°3.6′N 12°49′W. It causes rapid decompression and the break-up of the aircraft in mid-air. The wreckage settles in 6,700-feet deep water off the southwest coast of Ireland, 120 miles offshore of County Cork. No “mayday” call is received by Shannon ATC. ATC asks aircraft in the area to try to contact Air India, to no avail. By 07:30:00 GMT, ATC has declared an emergency and requests nearby cargo ships and the Irish Naval Service vessel LÉ Aisling to begin searching for the aircraft.

The bomb kills all 22 crew and 307 passengers. One hundred thirty-two bodies are recovered. The remaining 197 are lost at sea. Eight bodies exhibit “flail pattern” injuries, indicating that they had exited the aircraft before it hit the water. This is a sign that the aircraft had broken up in mid-air. Twenty-six bodies show signs of hypoxia (lack of oxygen). Twenty-five, mostly victims who were seated near windows, show signs of explosive decompression. Twenty-three have signs of “injuries from a vertical force.” Twenty-one passengers are found with little or no clothing.

Canadian law enforcement determines that the main suspects in the bombing are members of the Sikh militant group Babbar Khalsa. The attack is thought to be a retaliation against India for the operation carried out by the Indian Army Operation Blue Star to flush out several hundred Sikh militants who were within the premises of the Golden temple and the surrounding structures ordered by the Indian government, headed by Prime Minister Indira Gandhi. Though a handful of members are arrested and tried, Inderjit Singh Reyat, a Canadian national, remains the only person convicted of involvement in the bombing. Singh pleads guilty in 2003 to manslaughter. He is sentenced to 15 years in prison for building the bombs that exploded aboard Flight 182 and at Narita.

The subsequent investigation and prosecution lasts almost twenty years and is the most expensive trial in Canadian history, costing nearly CAD 130 million. The Governor General-in-Council in 2006 appoints the former Supreme Court Justice John C. Major to conduct a commission of inquiry. His report is completed and released on June 17, 2010. It concludes that a “cascading series of errors” by the government of Canada, the Royal Canadian Mounted Police (RCMP), and the Canadian Security Intelligence Service (CSIS) had allowed the terrorist attack to take place.