LaGuardia – Chicago – Denver – Portland – Seattle

On November 1, 1955 at 07:03 PM, LaGuardia – Chicago – Denver – Portland – Seattle experienced a crash involving Douglas DC-6, operated by United Airlines, with the event recorded near Longmont Colorado.

The flight was categorized as scheduled revenue flight and the reported phase was flight at a plain, valley crash site.

44 people were known to be on board, 44 fatalities were recorded, 0 survivors were identified or estimated. This corresponds to an estimated fatality rate of 100.0%.

Crew on board: 5, crew fatalities: 5, passengers on board: 39, passenger fatalities: 39, other fatalities: 0.

The listed crash cause is terrorism act, hijacking, sabotage. After a routine radio ramp check, Flight 629 taxied to runway 08R (80 degrees, right) and at 1844 the flight was in runup position where it was given ATC clearance for the flight to Portland, the first intended landing. The clearance, in part, included compulsory radio reports from the flight upon passing the Denver Omni and when climbing through 18,000 feet to its assigned flight altitude, 21,000 feet. Following takeoff the flight reported its "off time" to the company as 1852 and thereafter reported passing the Denver Omni at 1856. The latter communication was the last from the flight. About 1903 the Denver tower controllers saw two white lights, one brighter than the other, appear in the sky north-northwest of the airport and fall to the ground. Both lights were observed 30-45 seconds and seemed to fall with approximately the same speed. There was then a momentary flash originating at or near the ground which illuminated the base of the clouds, approximately 10,000 feet above. When the controllers observed the lights they initiated action to determine if any aircraft were in distress. Radio calls were made to all aircraft in the Denver area of responsibility and all except flight 629 were accounted for. It was soon learned that the flight had crashed and all 44 occupants had been killed. It was later confirmed that the disintegration of the aircraft in the air was caused by a bomb. Two weeks later, on November 15, investigators confirmed that an explosive device has been placed on board by John Gilbert Graham aged 23 who signed a US$ 37,500 life-insurance for his mother who was on board. Convicted guilty for murder and terrorism, he was sentenced to death penalty and executed on January 11, 1956.

Aircraft reference details include registration N37559, MSN 43538, year of manufacture 1952.

Geospatial coordinates for this crash are approximately 40.1672°, -105.1019°.