by Jonathan M. Stern
History of ATC
Air traffic control efforts began in earnest before that time. In the early 1930s, several commercial airlines began a somewhat informal system of air traffic control by giving weather and traffic advisories to their company aircraft over two-way radio. In 1935, several of these airlines established traffic control centers in Chicago, Newark, New Jersey, and Cleveland, Ohio.
The centers controlled traffic within 50 miles of these three airports. The United States began operating the centers in 1936. At the same time, approximately 20 control towers owned and operated by state and local governments had opened around the country, and, by 1946, the Civil Aeronautics Authority was operating 113 control towers and 24 centers.
Ground-based radar systems were in regular use for the separation of enroute IFR traffic in the late 1940s, but the use of radar was not widespread. Today, most air traffic control of IFR aircraft is through the use of radar.
Air traffic control services are generally provided by the Federal Aviation Administration and its employees. Some control towers are operated by state or local governments or, in a few cases, by businesses in the private sector.
A thorough understanding of the job of the air traffic controller allows pilots to tailor their flying, communication, and flight planning to best coordinate with the ATC system.
Moreover, by knowing the system, the tools that the controller has to work with, and the responsibilities of the controller, pilots are in the best position to obtain the services they need.