Air Traffic Control Comes of Age

The dramatic increase in air travel during the 1950s created a need for better airports and air traffic control.

Just as new aircraft technology produced a new generation of aircraft, new electronic technology produced answers to the growing problems of communications and managing air traffic.

By the end of the 1950s, the aviation infrastructure in the United States had grown intricate and highly advanced.

Radar and Precision Landing Systems

Radar-"radio detecting and ranging"-was developed by the British in the 1930s and widely used during World War II. By war's end, two precision landing systems were available for civil use: Ground Controlled Approach (GCA), which used radar, and Instrument Landing System (ILS), which used radio transmissions.

The first U.S. civilian control tower equipped with radar began operating at Indianapolis Airport in 1946. By 1951 the use of radar had begun to supercede pilot-reported positions by radio.

Radar Departure Control made its debut at Washington's National Airport in 1952. Until then, radar had been used only to confirm a pilot's reported position. With the new system, controllers could provide better and safer traffic flow into and out of airports.

With Ground Control Approach (GCA), a ground controller followed an approaching aircraft on a radar screen and instructed the pilot down to the runway. GCA was placed into operation at Washington's National Airport and Chicago's Municipal Airport in 1947. Although GCA was popular with the military, airline pilots preferred the competing ILS system.

Improved air traffic control techniques, particularly GCA, were critical to the success of the Berlin Airlift in 1948-49. For almost a year, a continuous relay of military and civilian transports landed in the Soviet-blockaded East German city every three minutes around the clock and in all weather, and kept the city's 2 million people fed.

Copyright The Boeing Company The Civil Aeronautics Authority in 1947 adopted the Instrument Landing System (ILS) as its primary landing aid, supplemented by GCA at busy airports. With ILS, a pilot relied on instruments that received altitude and direction data via radio transmissions and allowed the pilot to follow a glide path to the runway. ILS greatly reduced missed approaches and flight cancellations due to weather and enabled airports to handle more traffic.

Growing Pains and Growing Concerns

Despite steadily improving air traffic control, a series of airliner accidents over five months in 1951-52 aroused public concern. Although not related to air traffic control, the accidents led to an accelerated program of technical development and promoted new discussions on safety and traffic control.
Air traffic growth in the 1950s led to severe airport congestion and delays. In 1956 two airliners collided over the Grand Canyon. Two more midair collisions occurred in 1958 and another in 1960. These events prompted legislation that enabled aviation authorities to take corrective measures.

In the 1950s the Civil Aeronautics Administration, in cooperation with the Air Force, began installing long-range radars with a radius of 322 kilometers (200 miles). A network of overlapping radars was completed by 1965, allowing continuous monitoring of aircraft in controlled airspace.

The upsurge in air travel led to the development of modern airports. Chicago's O'Hare International Airport introduced the first "air bridges." Better known by the brand name "Jet Way," they provided sheltered passage between terminal and plane and sped up aircraft turnaround times. However, passengers now sometimes never even saw the airplane they were boarding.