The Grand Canyon collision
On the morning of 30 June 1956 two airliners, a Trans World Airlines Super Constellation and a United Air Lines DC-7, left Los Angeles within minutes of each other, bound for Kansas City and Chicago. They flew in uncontrolled airspace, in which pilots were responsible for avoiding each other and in which no controller tracked them. Over the Grand Canyon they collided, and both crashed. All 128 people on board died.
It was then the worst accident in the history of commercial aviation. The investigation found that the aircraft had been flying among towering clouds and that the crews probably did not see each other in time. There was no radar over that part of the country, and no one on the ground knew they were approaching.
A new system
The accident caused public alarm, and it came after a number of other collisions. Congress passed the Federal Aviation Act in 1958, which created a single agency, today's Federal Aviation Administration, with responsibility for the rules of the air, the control of traffic and the development of radar coverage.
Airways across the country were brought under radar control over the following years. The accident is a reminder that many procedures in aviation came into being after something went wrong.