Trans-Canada Air Lines Flight 304 was operated by a Vickers Viscount 700 aircraft owned by Trans-Canada Air Lines. On July 9, 1956, the No. 4 propeller of the aircraft tore loose from its engine over Flat Rock, Michigan in the United States, during a flight from Chicago, Illinois, to Toronto, Ontario, and Montreal, Quebec; one blade of the propeller sliced through the passenger section of the cabin, killing one passenger and injuring four passengers and one flight attendant. The aircraft diverted to Windsor, Ontario, in Canada, and the pilots carried out an emergency landing. The accident was the first to involve a Vickers Viscount aircraft in scheduled service, and was the first instance of a propeller loss on a turbo-prop aircraft.