This Week in Aviation History: United Flight 629

On November 1, 1955 a United Air Lines Douglas DC-6B exploded under un-natural circumstances that would later define the event as a dreadful “first.” United Air Lines Flight 629 originated in New York and had stopped in Denver, Colorado enroute to Seattle, Washington. An additional en-route stop was expected in Portland, Oregon. The aircraft made it as far as Longmont, Colorado.

There was a woman on board the flight by the name of Daisie King. She had boarded the plane at Denver’s Stapleton Airport, having been taken to the airport by her son, John Gilbert Graham and his family. While Mrs. King was saying goodbye to Graham’s wife and children, Graham attended to her baggage — including slipping a gift-wrapped package into her suitcase. The package contained dynamite, a clock and an Eveready Hot Shot battery.

Flight 629 suffered no mechanical problems during its trip West, although there were ground delays that had accumulated since leaving New York. Ironically, these delays turned out to be the only “fortunate” occurance of the entire trip: Graham devised his plan around a time calculation. By his reckoning, the device would explode over the Rocky Mountains, making recovery of any wreckage difficult, if not impossible. Thanks to the delays, it didn’t work out that way.

United 629 exploded over the flatlands near Longmont, Colorado at an altitude of near 5,000 feet. The explosion was seen from a distance, including the tower at Stapleton from which Controllers asked flights to check-in. When United 629 did not report, they had their answer.

Debris fell in two large groups and fuel from the freshly topped fuel cells fed a fire that burned for days. Even with the rending of the airframe and ensuing conflagration, soot and smudges were visible in some areas of the airframe that exuded the distinct smell of explosives. This residue was identified as dynamite, and remnants of the battery were also found — pointing to the ignition source.

These clues gave the investigators the location, the number four baggage hold. Fortunately for them, that hold had been emptied at Denver and filled again with only cargo and bags originating in Denver, making their search much more refined. From the location of the explosion and type of device, it would be a simple task to sever the tail of the airliner — killing five crew and 39 passengers. The question was why.

Further investigation revealed fragments of letters and other documents belonging to passenger Daisie King that were clearly in very close proximity to the source of the blast. As the Civil Aeronautics Board and FBI dug deeper, they became more interested in John Gilbert Graham. Graham was a convicted check forger who ran a drive-in that his mother owned, but his relationship with her was not pleasant. He had also tried to collect on insurance claims by claiming vandals had cut a gas line at the drive-in restaurant.

With this history in mind, his probation office and other court officials noted that Graham appeared remorseless. Interrogated by the police, Graham denied most points raised, but he conflicted himself and contradicted statements his neighbors and his wife had made. When he agreed to a search of his home, investigators found residual materials from bomb-making, and the insurance policy he had denied holding. Graham killed his mother and 43 other people for an insurance policy worth $37,500. He was charged with the crime upon signing a confession on November 14, just two weeks after the fatal bombing.

This is the first known instance of someone deliberately sabotaging an American airplane in flight. But for the deaths he caused on November 1, Graham paid the price for his greed. He was executed on January 11, 1956.

Editor’s note: A quick internet search will find “John Gilbert Graham” in some extremely unpleasant company and our’s turned up these alleged quotes:

“Can’t you just imagine the pilots and the passengers and Mother jumping around?” John Gilbert Graham

…with this response to a request for last words: “Yeah, I’d like you to sit on my lap as they close the door in there.” John Gilbert Graham, just prior to his execution