86 years ago on October 10th, 1933
A United Air Lines Boeing 247 from Newark, NJ exploded in what is believed to have been the first sabotage bombing of a commercial aircraft
The plane was quite a bit smaller than modern commercial flights, with only four passengers and three crew members aboard. All seven people were killed in the crash, and scraps of the plane were scattered over a wooded area near Chesterton, Indiana.
The plane had traveled from Newark to Cleveland and was on the second leg of its journey en route to Chicago when the explosion occurred. Witnesses on the ground reported hearing an explosion, then seeing the flaming debris falling as the plane came down just after 9pm. The plane crashed with such a speed that it cut through tree trunks and the wreckage burned for more than three hours.
Although similar to a fuel explosion, an investigation determined the initial cause to have been an intentional bombing, as the explosion blew off the rear of the aircraft and bent the metal outward, indicating an explosion from inside. The fuel tanks were also collapsed, showing they did not explode. Evidence indicated that the blast came from the cargo hold and it sheared off the tail of the aircraft, leading to a catastrophic drop from 1,000 feet. The tail of the aircraft was found nearly intact one half mile from the plane's fuselage. Although the FBI found the effects of the explosion similar to the result of high explosives like nitroglycerin or dynamite, no identifiable components from the bomb were discovered and the case remains unsolved to this day, with no known suspects or motive.