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The Role of an Air Traffic Controller Within the National Airspace System (NAS)

The National Airspace System (NAS) is a network of the U.S. airspace and it includes the following: airports/landing areas, air navigation facilities, information/services, rules, regulations, equipment, aeronautical charts, procedures, material, technical information and manpower.  The NAS is probably one of the most complex aviation systems in the world with the thousands of people, facilities, procedures and equipment that it consists of.  This network enables millions of people to travel safely and timely in the United States. There are system components shared jointly with the military included in this network.  Technological advances concerning the altitude and speed capability of jet aircraft are reflected in the system’s configuration, as well as satellite-based and microchip navigation equipment.  The U.S. has adopted the primary elements of the International Civil Aviation Organizations (ICAO) in order to conform to international aviation standards as well.

There are approximately 14,500 air traffic controllers with jobs at the National Airspace Systems, as well as 4,500 aviation safety inspectors and 5,800 technicians required to operate and maintain services.  Included in the NAS are 41,000 operational facilities, with over 70,000 pieces of equipment that consist of everything from radar systems to communication relay systems.  The average number of flights that the NAS services every day is about 50,000.

Airspace is broken down into classifications that fall into either a controlled airspace or a non-controlled airspace.  In the U.S., airspace consists of the following types of classes: Alpha, Bravo, Charlie, Delta, Echo and Golf.  Non-controlled airspace includes airports without operational control towers and they are referred to as uncontrolled airfields.  In the absence of an air traffic controller, pilots in these areas are responsible for position and separation using a Common Traffic Advisory Frequency (CTAF) for that airport.  Class Golf airspace is completely uncontrolled airspace that extends from the surface to 700 or 1200 ft. AGL dependent upon the floor of the overlying Class Echo.  The only frequency used for radio communications by pilots in this area is CTAF.

Controlled airspace includes the remaining classifications.  Class Alpha begins and includes 18,000 ft. MSL and continues up to 60,000 ft. MSL.  This is the most controlled airspace.  Class Bravo airspace extends from the surface up to 10,000 ft. AGL and is the area around the busiest airports and it is also heavily controlled.  Class Charlie airspace reaches from the surface to 4,000 ft. AGL above the airport. Class Charlie only exists over airports with an operational control tower and radar approach control service.  Two way radio communications are required by the pilots and the air traffic control service.  Class Delta is airspace that exists from the surface to 2500 ft. AGL above the airport.  This Class D airspace surrounds airports with an operating control tower only.  The airspace that lies between Classes A, B, C and D is Class Echo and it extends from either the surface or the roof of the airspace and ends at the floor of the controlled airspace above. Class Echo is for planes transitioning from the terminal to en route state.

Now air traffic controllers with college education consist of “terminal controllers” and “en route controllers” both of which play important parts in the NAS. They handle different areas of the airspace.  A simple way to explain the difference between the two is that the En Route Controller handles the air traffic at higher altitudes in between airports while the Tower Controller handles the planes that are taking off and landing at the airport within a certain distance of the airports airspace. The NAS requires more than 14,000 individuals with air traffic controller training to keep our airways safe and orderly. They are an integral part of the National Airspace System.

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