It was October 6, 1955, and United Air Lines Flight 409 was running one hour and eleven minutes late. It had departed Idlewild Airport in New York and stopped at Chicago and Denver. The Douglas DC-4 propliner was now bound for Salt Lake City and then San Francisco. There were 63 passengers onboard, including military personnel returning home after duty and five female members of the Mormon Tabernacle Choir, who had toured in Europe.