A horrible air disaster occurred in the skies over the Grand Canyon in 1956, when a two commercial aircraft, operated by Trans World Airlines and United Airlines and flying in clear skies, collided and crashed, killing more than 100 people. As a result of this tragedy, Congress in 1958 established the Federal Aviation Administration (FAA), to regulate and oversee the operation of aircraft in the skies over the United States, which were becoming quite congested. The resulting structure of air traffic control has greatly increased the safety of flight in the United States, and similar air traffic control procedures are in place over much of the rest of the world as well.

Rudimentary air traffic control (ATC) existed well before the Grand Canyon disaster. As early as the 1920s, the earliest air traffic controllers guided aircraft in the vicinity of airports manually, using lights and flags, while...