page_title: 1956 Grand Canyon mid-air collision
section_title: Collision
hierarchical_section_title: 1956 Grand Canyon mid-air collision / Collision
caption_attribution_description: Grand Canyon landscape
context_page_description: The Grand Canyon mid-air collision occurred on June 30, 1956, when a United Airlines Douglas DC-7 struck a Trans World Airlines Lockheed L-1049 Super Constellation over the Grand Canyon National Park. All 128 onboard both flights perished, making it the first commercial airline crash to result in more than 100 deaths.
  The collision took place in uncontrolled airspace, where it was the pilots' own responsibility to maintain separation. This highlighted the antiquated state of air traffic control, which became the focus of major aviation reforms.
context_section_description: At about 10:30 a.m. the flight paths of the two aircraft intersected over the canyon, and they collided at an angle of about 25 degrees.  Post-crash analysis determined that the United DC-7 was banked to the right and pitched down at the time of the collision, suggesting that one or possibly both of the United pilots saw the TWA Constellation before impact and attempted evasive action.
  The DC-7's upraised left wing clipped the top of the Constellation's vertical stabilizer and struck the fuselage immediately ahead of the stabilizer's base, causing the tail assembly to break away from the rest of the airframe. The propeller on the DC-7's left outboard, or number one engine, concurrently chopped a series of gashes into the bottom of the Constellation's fuselage. Explosive decompression would have instantaneously occurred from the damage, a theory substantiated by light debris, such as cabin furnishings and personal effects, being scattered over a large area.
  The separation of the tail assembly from the Constellation resulted in immediate loss of control, causing the aircraft to enter a near-vertical, terminal velocity dive. Plunging into the Grand Canyon at an estimated speed of more than 477 mph (700 feet per second (210 m/s)), the Constellation slammed into the north slope of a ravine located on the northeast slope of Temple Butte and disintegrated on impact, instantly killing all aboard. An intense fire, fueled by aviation gasoline, ensued. The severed tail assembly, badly battered but still somewhat recognizable, came to rest nearby.
  The DC-7's left wing to the left side of the number one engine was mangled by the impact and was no longer capable of producing substantial lift. The engine had been severely damaged as well, and the combined loss of lift and propulsion left the crippled airliner in a rapidly descending left spiral from which recovery was impossible. The Mainliner collided with the south side cliff of Chuar Butte and disintegrated, again instantly killing all aboard.
caption: The Grand Canyon sites of the two aircraft impacts.
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