1955 — Nov 1, United Flight 629 Blown-up (relative of passenger bomb), Longmont, CO–44

— 44 Aerospaceweb.org. Commercial Airliner Bombings, “1 Nov 1955-United Flight 629”
— 44 Aircraft Crashes Record Office (Geneva, Switzerland). Colorado, USA, N37559.
— 44 AirDisaster.Com. Accident Database. Accident Synopsis 11011955.
— 44 Aviation Safety Network. Criminal Occurrence Description. United Air, 01 Nov 1955.
— 44 CAB. AIR. United Air Lines…Near Longmont, Colorado, November 1, 1955.
— 44 Cornell, James. The Great International Disaster Book (Third Edition). 1982, p. 370.
— 44 Duwe, Grant. Mass Murder in the United States: A History. McFarland, 2007, p. 28.
— 44 NationMaster.com, Encyclopedia, List of notable accidents & incidents on com. aircraft.
— 44 NFPA. “Summary of Large Loss Aircraft Fires.” Quarterly…NFPA, 49/4, Apr 1956, 395.

Narrative Information

Aerospaceweb.org: “United 629 was a Douglas DC-6B en route from Denver, Colorado, to Portland, Oregon. Nine minutes after takeoff, the aircraft was destroyed by a bomb composed of 25 sticks of dynamite. The explosive appeared to have detonated in the number 4 baggage compartment causing the plane’s tail to disintegrate and sending it out of control. All 44 passengers and crew were killed in the crash. A man named Jack Graham was arrested for the act. Graham’s mother, Daisie King, was on the plane and he hoped to claim $37,500 of life insurance policies he had bought from vending machines at the airport just before departure. Ironically, the life insurance policies were invalid since his mother had not signed them. Graham apparently had a long grudge against his mother as well as a criminal history. He had been arrested for forgery in 1951 and had also collected insurance on one of his mother’s restaurants that mysteriously exploded. Graham was put to death in the gas chamber a year after the bombing.” (Aerospaceweb.org. Commercial Airliner Bombings, “1 November 1955 – United Flight 629.”)

AirDisaster.com: “The aircraft exploded nine minutes after takeoff from Denver due to detonation of an explosive device. John Graham placed the bomb in his mother’s luggage to collect $37,000 in life insurance money. He was executed for the crime some 10 years later.” (AirDisaster.com. Synopsis 11011955.)

CAB: “On November 1, 1955, at approximately 1903, a midair explosion of disintegrating force occurred aboard United Air Lines Flight 629 and the aircraft, a DC-6B, N 37559, crashed near Longmont, Colorado. The crew of five and 39 passengers were fatally injured. The aircraft was destroyed.

“United Air L-Lines Flight 629 is scheduled daily between LaGuardia Field, New York, and Seattle, Washington. There are scheduled stops over the route at Chicago, Illinois; Denver, Colorado; and Portland, Oregon….On November 1, 1955, this operation was routine to Denver where the flight landed at 1811….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 Plight 629 were accounted for. It was soon learned that the flight had crashed and all 44 occupants had been killed.

“The wreckage of the aircraft was spread along a north-northwest heading and covered an area of approximately six square miles. Within this area all the major components of the aircraft were found. The tail group was located about 4,600 feet south-southeast of two deep craters which contained large portions of both wings, the four powerplants, and main landing gear. The forward fuselage was roughly 600 feet north of the craters and the left outer wing panel was found approximately 600 feet south of the craters. This scatter of the heaviest and largest pieces of wreckage showed that the craft disintegration began in flight at an appreciable altitude and that the separation of the tail assembly occurred before separations of the wings and forward fuselage.

“The aft fuselage was found to have been torn into a multitude of bits and pieces. Portions of the structure were strewn over the ground in a wide path extending south-southeast approximately four miles from the main wing wreckage, the less dense fragments being at the farther distances. Pieces of very low density material, such as paper and cabin insulation, ware found as far as nine miles south-southeast. Many pieces of the aft fuselage comparable in density to the tail group were found in the area adjacent thereto. This dispersal indicates that the aft fuselage was shattered simultaneously with the separation of the tail assembly and that winds aloft carried the less dense pieces considerable distance during their fall to the ground. The severity of fragmentation indicates extremely violent shattering of this section of the airplane….

In addition to severe breakup of the structure, extensive fire damage occurred. This was due to ignition of the fuel and oil which saturated the ground in and around the craters. Despite efforts to extinguish the fires, burning continued for three days. The fire pattern in all cases clearly established that the fires occurred following impact.

“At an early phase of the Civil Aeronautics Board’s investigation its investigators bee aware that an explosion had occurred aboard this flight while at an altitude of several thousand feet above the ground. It was also clear that the explosion was of such great intensity that it would be unusual for it to have been caused by any system or component of the aircraft. This awareness was strengthened by smudge marks and odor characteristic of an explosive that persisted on pieces of the fragmentized wreckage known to have been part of the fuselage structure in the area of the No. 4 baggage compartment. The marks and odor were particularly noticeable on passenger baggage, mail sacks, and clothing known to have been contents of this compartment….

“Numerous pieces of the aircraft and its contents, bearing the sootlike smudges, were subsequently examined in the F.B.I. laboratory to determine, if possible, what type of explosive material caused the destruction of the aircraft. The chemical analysis revealed that the residues were those to be expected from the explosion of dynamite which contained sodium nitrate. The analysis further disclosed that the residues on many of the parts contained manganese dioxide, a major component of the mixture contained in dry cell batteries. Eleven pieces of material which could have originated from an Eveready “Hot Shot” battery were found. These items are two of the basic components of one type of a bomb….

“…by meticulously piecing together hundreds of pieces of the torn and shattered fuselage on a chicken-wire covered wooden frame mockup of the original DC-6B fuselage, Board investigators specifically determined that a dynamite-type explosion had occurred within the No. 4 baggage compartment of the airplane. Consequently, on November 7, six days after the accident, the Board notified the Denver office of the Federal Bureau of Investigation of its findings so that the apparent criminal aspects involved could be pursued immediately….

“On November 14, 1955, agents of the Federal Bureau of Investigation took into custody John G. Graham, the son of one of the passengers. Thereafter, he was indicted for acts leading to the destruction of the aircraft by means of a bomb explosion.” (CAB. AIR. United Air Lines…Near Longmont, Colorado, November 1, 1955.)

Sources

Aerospaceweb.org. Commercial Airliner Bombing History. Accessed 12-21-2008 at: http://www.aerospaceweb.org/question/planes/q0283.shtml

Aircraft Crashes Record Office (Geneva, Switzerland). Colorado, USA. Accessed 3-3-2009 at: http://www.baaa-acro.com/Pays/Etats-Unis/Colorado.htm

AirDisaster.com. Accident Database. Accident Synopsis 11011955. Accessed at: http://www.airdisaster.com/cgi-bin/view_details.cgi?date=11011955&reg=N37559&airline=United+Airlines

Aviation Safety Network. Criminal Occurrence Description. United Air Lines Flight 629, 01 Nov 1955. Accessed 2-21-2009 at: http://aviation-safety.net/database/record.php?id=19551101-0

Civil Aeronautics Board. Accident Investigation Report. United Air Lines, Inc., Douglas DC-6B, N. 37559, Near Longmont, Colorado, November 1, 1955. DC: CAB, May 14, 1956, 7 pp. Accessed 73-2020 at: https://www.google.com/books/edition/United_Air_Lines_Inc_Douglas_DC_6B_N_375/yE_6WhLy6LEC?hl=en&gbpv=1&dq=United+Air+Lines,+Inc.,+Douglas+DC-6B,+N.+37559,+Near+Longmont,+Colorado,+November+1,+1955.&pg=PP3&printsec=frontcover

Cornell, James. The Great International Disaster Book (Third Edition). New York: Charles Scribner’s Sons, 1982.

Duwe, Grant. Mass Murder in the United States: A History. McFarland, 2007.

National Fire Protection Association. “Summary of Large Loss Aircraft Fires.” Quarterly of the National Fire Protection Association, Vol. 49, No. 4, April 1956, pp. 393-395.

NationMaster.com. Encyclopedia. “List of Notable Accidents and Incidents on Commercial Aircraft.” Accessed 12-15-2008 at: http://www.nationmaster.com/encyclopedia/List-of-notable-accidents-and-incidents-on-commercial-aircraft