The Evolution Of Air Traffic Control

Next month, on October 20th, the industry will celebrate the International Day of the Air Traffic Controller. While air traffic control systems are now comprehensive and employ thousands of people worldwide, many years ago, it started with a man and a flag that guided pilots in take-offs and landings. The system has significantly advanced, but air traffic control remains the underdog in keeping the airspace safe.

Humble beginnings

Although the first scheduled passenger flight in 1914 was one of the most significant landmarks in aviation history, air traffic control (ATC) didn’t emerge until years later. Before ATC kickstarted, pilots would use visual navigation methods, such as compasses and maps, to fly and land planes.

In 1920, London’s Croydon Airport was the first to introduce an ATC tower. The ‘Aerodrome Control Tower’ was mainly used for basic traffic and weather guidance for pilots using radio. Meanwhile, in the United States, the Air Commerce Act of 1926 was the first time ATC was somewhat recognized when the secretary of commerce was put in charge of setting air traffic rules, certifying pilots and aircraft, establishing airways, and operating navigation systems.

A few years later, in 1929, following Charles Lindbergh’s first solo flight across the Atlantic – nonstop from New York to Paris in 1927 – the first US air traffic controller was hired, a pilot and mechanic named Archie W. League. League’s control tower was far less complicated than today’s standards.

Every day, League would carry a chair, umbrella, lunch, water, notepad, and signal flags in a wheelbarrow to an airfield in St. Louis and guide pilots on departures and landings. He had two flags, one for ‘Go’ and one for ‘Hold,’ and this was the first coordinated air traffic control.

This began League’s long career of developing the federal air traffic control system. He joined the Federal service and became the Federal Aviation Administration’s (FAA) Traffic Service director after retiring as an Assistant Administrator in 1973, according to the regulator.

Following League’s guide flags came light guns, but in 1930, the first “radio-equipped” control tower was established at Cleveland Municipal Airport, changing the course of ATC. Over the five years following, 20 more cities would adopt the same technology.

Photo: FAA

In 1935, a US consortium opened the first ATC station in Newark, New Jersey, according to the FAA. The station would monitor the position of planes with the use of maps and blackboards and would use telephones to keep in touch with pilots and airline dispatchers.

Then in 1936, the Bureau of Air Commerce established the three air route traffic control centers (ARTCC), which directed the movement of planes from departure and landing following the rise of midair collisions. The first was established in Newark and then followed by the opening of two in Chicago and Cleveland. The three were the “forerunners” of today’s 22 operating ARTCCs in the US.

The emergence of radar

The use of radar – RAdio Detection And Ranging – marked the biggest advancement for ATC after being useful during World War II, spearheaded by the British government. Plane Finder explains the technology was tested by ‘sound mirrors,’ which used a radar dish and microphone to detect engine sounds from far away.

The successful demonstration of the technology led to the development of radar stations along the south coast of England called the “Chain Home,” which was Britain’s primary defense during the war.

The use of radar spread to other nations as well, and eventually, the US military chose the Gilfillan Brothers Inc. – now ITT-Gilfillan – to develop an official radar system in 1942. Following WWII, by 1950, the Civil Aeronautics Administration (now the FAA) deployed its first Airport Surveillance (ASR-1) system. The FAA described:

“As the antenna turned, controllers watched their scopes for “blips” that indicated the position of aircraft in early radar systems. The use of radar to provide separation for en route air traffic followed the application of this technology in the terminal area.”

Photo: FAA

Then, in 1952, the CAA established its radar departure control procedures at the Washington National Airport after years of modifying the technology from the war.

The era of automation

The automation of radar technology was synonymous with the Jet Age. The growth of tourism worldwide meant a much more sophisticated approach to ATC was needed. The US was at the forefront of the new era of aircraft navigation, and in 1961, the FAA began to develop a system that would “use data from both ground radar and from airborne radar beacons” after ongoing calls for computer technology to control air traffic.

By 1967, a prototype computer developed by IBM was delivered to the Jacksonville Air Route Traffic Control Center. The first phase of the system, called the NAS En Route Stage A, was to automatically distribute flight-plan data through the Computer Update Equipment (CUE), which meant controllers could see flights in three dimensions. The FAA said that by 1973, all en route centers in the contiguous US had adopted this system.

The second phase was more detailed and involved radar data processing. This computer, through alphanumeric codes, could identify a plane’s identity, altitude, and other essential characteristics.

Meanwhile, the FAA also created a system for controllers in airport terminals, called ARTS III – Automated Radar Terminal Systems – and by the 15th of August 1975, it was operated by all of the US’ busiest airports. Eleven days later, the FAA finally completed phase two of the NAS En Route Stage A.

According to a 1973 report by the General Accounting Office, the ARTS III system was initially contracted at $51.3 million but rose to $64.5 million in the mid-70s due to multiple system changes.

Now, 50 years after the broad adoption of radar and radio technology in aviation, the world of air traffic control has continued to grow. From filing flight plans with air traffic control to using radar screens for tracking aircraft progress through the sky, ATC has become what League could never have imagined in 1929.

Remote ATC is also gaining traction thanks to technological advancements. In 2021, London City Airport became the world’s first major international airport to completely utilize remote towers.

Such initiatives are likely to be a staple in aviation in the coming decades. We can expect plenty of evolution here as airports and airlines remain keen to improve safety and efficiency.

Still not always smooth sailing

Despite all the developments throughout the years, there are still challenges in the field of air traffic control. This month’s ATC drama in the UK is an instance of this. Flights were disrupted all across Europe due to a technical glitch, causing an investigation to be launched and over $120 million to be lost in airline expenses alone.

Moreover, air traffic controllers are keen to improve working conditions, with several strikes conducted in recent months. Notable examples are in France, where industrial action has caused a significant impact on flight operations throughout the market. Moreover, key airports around the world are continuing to face ATC shortages, forcing further disruption.

What are your thoughts about the evolution of air traffic control? What do you make of the changes over the decades? Let us know what you think of the progression made in the comment section.

Sources: FAA, Plane Finder, GOA report