Two commercial airliners collided 21,000 feet over the Grand Canyon, killing all 128 people on board the two planes.
The crash caused both airliners -- a Trans World Airlines Super Constellation L-1049 and a United Airlines DC-7 -- to fall to the ground. Each had flight plans that should not have taken them over the area, an investigation eventually revealed. It was speculated that the two pilots were giving their passengers a scenic view of the national park.
This was a crucial turning point in aviation history and led to the creation of the Federal Aviation Administration. Also attributed to the crash is the inception of nationwide radar coverage, collision avoidance systems and flight data recorders.