In the early days of aviation, airplanes were mostly used as joy rides, in air shows, and for just general "barnstorming." Even into the 1920s, debate occurred regarding whether the airplane had a useful purpose, and one of the main concerns was the inability of planes to fly in bad weather. With the development of radio navigation aids, which would eventually lead to the flight instruments of today, radio landing aids were installed at larger airports. These airports became the first hubs for successful air travel and were connected to each other via airways, which are similar to highways that connect large cities. However, just as highways funnel traffic into a city, causing traffic congestion and possible collisions, airways also experience similar problems near airports, making methods of controlling air traffic necessary.

In the beginning, air traffic control (ATC) was mostly implemented via such...