When most of us step onto a commercial flight, we take for granted the job that air traffic controllers do, not to mention the systems that enable aircraft to navigate successfully. There is quite a lot involved in air traffic control; let’s investigate how it works.
As an example, airspace in the United States is split up into 21 separate zones, with each one of those zones then divided into sectors. Within each zone are pockets of airspace, around 80 kilometers in diameter, which are referred to as TRACON (Terminal Radar Approach CONtrol). The FAA has designed the air traffic control system around these TRACON divisions, with various personnel within the system assigned certain zones to patrol.
In the United States, the Air Traffic Control System Command Center (ATCSCC) is responsible for all air traffic control, while Air Route Traffic Control Centers (ARTCC) manage traffic within all sectors of its center. Terminal Radar Approach Control (TRACON) handles departing and approaching aircraft within its space, and Flight Service Stations (FSS) provide critical data, such as weather, route, terrain, flight plan and more.
So you can see from this that there is something of a division of labor. And all of these various sectors are then knitted together to create the air traffic control system as a whole.
Readers familiar with defensive systems in sport will understand that air traffic control effectively operates around a ‘zonal marking’ system. When aircraft move through US airspace, it is monitored by the air traffic controllers and teams that are responsible for that particular zone. And then, once it passes through the zone, the air traffic control team then passes the aircraft on to the team that is responsible for the airspace that the aircraft is about to enter.
Controllers are in touch with pilots at all times, with communication between the ground and the pilot absolutely essential. Trained pilots rely on this information to a signifcant extent, even though they are also trained to fly aircraft off instruments alone as a failsafe mechanism. Nonetheless, this is significantly trickier than flying via collaboration with air traffic control.
In order to ensure that aircraft behave predictably, the flightpaths of aircraft are filed with air traffic control. This enables the controllers to follow aircraft more easily, and pilots will rapidly be contacted if a plane veers off its expected flight path, or is seen to be behaving erratically. Every aspect of a flight is already decided before the plane takes off; for example, commercial flights are all assigned designated runways ahead of their destination.
All flight plans held by air traffic controllers and the computerized system include:
- Airline name and flight number
- Type of aircraft and equipment
- Intended airspeed and cruising altitude
- Route of flight
It is then the responsibility of the pilot to transmit this data to the air traffic control towers. Once this flight path has been approved, the plane will be cleared for takeoff, at which point control will be passed to the air traffic control tower, where ground controllers advise pilots on prevailing conditions and any other important information that needs to be conveyed at this point.
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Once the plane is in the air, the transponder is activated, and this sends real-time information to air traffic control. If the transponder fails to function at any stage, this would be considered a red flag for air traffic controllers, who would instantly make contact with the plane in question. The transponder signal provides the controller with the aircraft flight number, altitude, airspeed, and destination.
As a plane passes through each stage of a flight, it is passed to the various teams that deal with the appropriate stages of the process. At the point of landing, the local controller checks the runways and skies about the destination airport and will provide clearance to land only when it has been confirmed that it is safe to do so. Pilots also receive up-to-date weather information and other important data right up to the point of landing.
Once the plane is safe and sound on the ground, the final part of the process is for the local controller to direct the plane to an exit taxiway. Even at this stage, the plane is monitored closely, in order to ensure that it doesn’t clash with any ground traffic, or interfere with ground vehicles.
There is, of course, a lot more to the process than it is possible to convey here, but that’s a basic rundown of precisely how air traffic control works, and how flights are monitored to ensure safety.