When you board an airplane, it is located on the ramp of an airport. This is the ground part of the NAS.
Air Traffic Control Tower:
The flight is under the supervision of the Air Traffic Control Tower until it is about 5 miles from the runway. The tower is the most recognized symbol of the NAS. The tower controllers are located in the glass booth you see at an airport at the top of the tower. When the pilot taxis the
aircraft to the runway and departs the airport, the airborne part of the flight begins.
Once the airplane is five miles beyond the airport, the control of the plane is transferred to the Terminal Radar Approach Control Facility (or TRACON). The TRACONs sequence and separate aircraft as they approach major metropolitan areas. There are over 185 TRACONs in the United
States. TRACONs provide air traffic control services from just outside the airport to about 40 miles away. Controllers and pilots are in constant communication. The controllers instruct the pilots on safe altitude, course and speeds to avoid other aircraft. Terminal controllers work with pilots to ensure the flight path is smooth and free of other traffic. The pilots acknowledge these directions and maneuver the airplanes safely.
En Route Airspace:
For most commercial flights, when the airplane departs the terminal airspace it enters the en route airspace. The way pilots get from one place to another is by highways, known as routes, in the sky. Some routes are primarily north and south, others run east to west. Various routes, or lanes, operate at different altitudes.
Twenty Air Route Traffic Control Centers (or ARTCCs)
control and monitor airplanes over the continental United
States and between airports. En route airspace extends
beyond the United States coastline by approximately 100
miles and is bordered on the north by Canada and Mexico to
the south. En route controllers work with pilots to ensure the
flight path is smooth and free of other traffic.
For flights over the ocean, United States controllers control the operations over part of the Atlantic, Pacific, and Arctic Oceans. These operations are very different from controlling aircraft over land. Once outside radar range, controllers must rely on periodic radio communications of position reports to determine the aircraft's location. The United States is responsible for almost 80 percent of the world's controlled oceanic airspace.
When a flight is approaching the airport, it descends from the en route or oceanic airspace into terminal airspace, where the TRACON controller efficiently sequences the airplane toward the runway. The tower controller ensures that the runway is clear for landing, the ground controller
issues the instructions to get to the ramp where the ramp operators ensure the aircraft is quickly moved to the proper gate.
Monitoring the entire operation is the David J. Hurley Air Traffic Control System Command Center ATCSCC), located in Herndon, Virginia. They receive an electronic picture of flights in the NAS from the ARTCC's across the country. The ATCSCC is responsible for ensuring the efficient use of all NAS resources through interaction with the FAA control facilities and airline operations centers. This interaction allows the ATCSCC to develop guidelines, such as arrival/departure restrictions or alternative routings, to ensure that the operation of the NAS remains efficient. The exchange of information consists of equipment outages, congestion areas, and weather information to allow everyone including the users to participate in a collaborative decision making process for operating the NAS.
There are about 3,300 airports in the United States that are considered significant to the capacity of the NAS. 413 of these airports are considered primary airports. These primary airports handle the vast majority of scheduled commercial flights. Each primary airport sees more than ten thousand passengers annually. There are over 600,000 active pilots operating more than 280,000 aircraft.
commercial airplanes that carry people and cargo,
small airplanes used by private pilots,
helicopters, including those that are used for medical evacuation operations,
business jets, and
balloons and other craft.
Almost 30,000 FAA employees are actively involved with the monitoring and control of aircraftthrough the NAS. All these people, working together, result in safe, secure, and efficient flights.