Air traffic control parallels the evolution of aircraft

The evolution of air traffic control parallels the evolution of the aircraft.

In aviation’s early days, the primary commercial use of civil aircraft was to carry the mail.

The robust National Airspace System that we know today did not exist. Flight, even when carrying the mail, was limited to daylight visual flight rules weather conditions.

Essentially, pilots in open cockpits flew point-to-point using visual landmarks for navigational guidance.

In 1919, the International Commission for Air Navigation was created to develop General Rules for Air Traffic. These rules were applied in most countries and were the earliest form of air traffic control. By the late 1920s, it became apparent that general rules were not adequate to prevent collisions; airports began to provide a form of air traffic control based on visual signals. Early controllers actually stood on the field, waving flags to communicate with pilots.

The increased demand for faster airmail service and the associated potential for profit led to the enactment of the Kelly Airmail Act of 1925, which inspired the development of a more sophisticated means of navigation. Compliance required the development of capability to support flight after dark and during periods of reduced ceiling and visibility.

One of the first attempts to develop a marked route structure was the lighted airway system, which consisted of a series of bonfires located at 10-mile intervals. In addition to the fire, a visual Morse Code signal was used to inform the pilot of his location.

The signals used were flashing the Morse Code letters, “W, U, V, H, R, K, D, B, G, and M.” It was repeated at 100-mile intervals.

By 1930, more aircraft were being fitted with radio communication; air traffic control towers began to replace the flagmen. The first radio equipped air traffic control tower in the U.S. began operation at Cleveland Municipal Airport in 1930. By 1932, almost all airline aircraft were being equipped for radio-telephone communication; about 20 air traffic control towers were operational by 1935.

The first Navy air traffic control tower opened on June 30, 1938, at NAS San Diego, now known as NAS North Island. Two Navy radiomen staffed the facility. An aviation machinist mate was later added as a temporary additional duty assignment.

Prior to World War II, the application of aviation for tactical and non-tactical missions was the catalyst for the growth of aviation as it is known today.

In addition to the military value of aviation, the potential profit from using aircraft to carry cargo and passengers became apparent to the civil sector. The development of the infrastructure to support aviation was accelerated by the lessons learned during World War II. These developments led to the requirement for a more robust, dependable and safe infrastructure to support the growth of civil aviation.

The transition from the lighted airway structure to a support infrastructure that could provide 24-hour-per-day, all-weather service was accomplished through a phased series of developments.

The first phase was the development and deployment of low frequency beacons. These beacons were used to define the colored airway structure (e.g., blue and amber airways). The colored airways provided navigational guidance in the enroute structure; beacons were also used to define approaches into the terminal areas.

Capabilities developed during the war, such as radar, developed by the British, and tactical air navigation, developed by the U.S. Navy, were instrumental in achieving dependable navigational guidance, and facilitated the transition to all-weather operations.

The development of radar enabled the fielding of long-range and short-range air defense systems and the airport precision approach radar. They evolved into the backbone of the enroute air traffic control system, while the airport precision approach radar, complemented by a short-range terminal surveillance radar, became the ground-controlled approach system. The ground-controlled approach system was the technical breakthrough that allowed aviation operations to continue during periods of low ceilings with reduced flight visibility.

Tactical air control was developed during World War II. Air control was exercised by Air Support Control Units, first used by the Germans and British and later adopted by the U.S. in the campaign at Guadalcanal and, to a small extent, in North Africa. As a result of these experiences, a concentrated effort was made to set up and train groups of personnel for “air support parties,” which were first used in the Pacific and the Aleutian Campaign of 1943. In the Attu operations in May of that year, the first afloat Air Support Control Units was employed. The Air Support Control Units consisted of three officers and a radioman who operated from a card table located on USS Pennsylvania (BB 38). In spite of inclement weather, 10 close air support missions were flown and controlled by this unit during the amphibious phase of the operation.

In late 1946, the Air Support Control Units were commissioned and the unit name changed to Tactical Air Control Squadron. Today, there are four TACRONs. Two serve the Atlantic Fleet (TACRON 21 and 22), and two serve the Pacific Fleet (TACRON 11 and 12). TACRONs have participated in many theaters and routinely deploy detachments with amphibious ready groups worldwide.

After World War II, civil air traffic operated primarily in accordance with instrument flight rules, while military traffic flew in a visual flight rules environment. Civil traffic was limited to low altitudes because of the operational characteristics of civil aircraft. Military activity consisted primarily of takeoffs from home stations, transit to training areas, and return, while civil flight developed its now-familiar point-to-point patterns. Military and civil users increased their dependence on radar for both enroute and terminal guidance. Increased deployment of the very high frequency omni-directional range and the tactical air navigation systems augmented the deployed non-directional beacons. These emerging innovations resulted in a robust aviation support infrastructure.

In 1950, the first attempt was made to provide the aircraft carrier pilot with instrument approach information, using the AN/SPN-8 precision azimuth information, which is the “forefather” of the systems used today.

On August 12, 1957, an F3D Skyknight, with Lt. Cmdr. Don Walker aboard, landed on USS Antietam (CVA 36) at sea off of Pensacola, Florida, using the Automatic Carrier Landing System. This landing began the first shipboard test of ACLS, designed to bring aircraft aboard in all weather conditions without assistance from the pilot. By August 20, 50 fully automatic landings were completed. This system and the associated tests were a result of the 1948 Navy-stated requirement for a fully automatic landing system to achieve an all-weather operating capability.

The economic benefit of carrying passengers and cargo began to exceed the economic benefit of the U.S. mail contracts, so the aviation industry began its expansion into a nationwide enterprise. The introduction of jet-powered aircraft, developed in the latter stages of World War II, to the civil sector allowed them to compete with the military for access to airspace, not only in the low altitude environment but also in the high altitude stratum. This competition led to a demand for increased control.

A number of near and actual midair collisions and concerns about aviation safety ultimately led to Public Law 85-726, now known as the Federal Aviation Act of 1958. It created the Federal Aviation Agency (later re-named the Federal Aviation Administration) and marked the beginning of the end of military dominance of airspace and the rules and regulations governing flight operations within the U.S.

This legislation mandated that the FAA would be the single manager of airspace for the nation, supporting and regulating aviation activities by both civilians and military with a single set of rules and regulations. In addition, the FAA would be responsible for developing and fielding the equipment used to support the provisioning of air traffic control related services in the environment subsequently referred to as the National Airspace System.

A Memorandum of Agreement was initiated between the FAA and the military services describing the process and procedures for requesting the delegation of airspace from the FAA to a requesting military organization.

In the early 1970s, in recognition of an increased demand for ATC-related services, the FAA deployed its first computer-based system to support enroute operations. The IBM 9020 computer, initially deployed in the Jacksonville Air Route Traffic Control Center, led the way to an automated infrastructure supporting the provision of air traffic control services in the U.S.

The Navy, in recognition of the transition from manual air traffic control to a system featuring automation, began to restructure its organization. Manual approach controls were upgraded to become radar approach controls. Ground controlled approach units were merged with the air station Air Traffic Control Division into a single organization.

The result of this transition was the creation of the modern day air traffic control facility.

NAS Corpus Christi was commissioned March 11, 1941. On August 6, 1986, the airfield at NAS Corpus Christi was rededicated in memory of Lt.j.g. Myron Truax, a Dallas, Texas, native, who served with great distinction from 1943 until 1946.

For 77 years, air traffic control specialists stationed at NASCC have ensured the Navy’s mission to maintain, train and equip combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas.