Air Traffic Control (ATC)

Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of traffic, and provide information and other support for pilots. In some countries, ATC plays a security or defensive role, or is operated by the military.

Air Traffic Control Room

ATC :- Increasing traffic density, in particular around airports, means that we need a method of air traffic control (ATC) to manage the flow of traffic and maintain safe separation of aircraft. The ATC The ATC system is based on secondary surveillance radar (SSR) facilities located at strategic sites, at or near airfields. Ground controller use the SSR  system to identify individual aircraft on screens.

Secondary Surveillance Radar

How Air Traffic Control Works :-

During peak air travel times in the United States, there are about 5,000 airplanes in the sky every hour. This translates to approximately 50,000 aircraft operating in our skies each day. How do these aircraft keep from colliding with each other? How does air traffic move into and out of an airport or across the country?

The task of ensuring safe operations of commercial and private aircraft falls on air traffic controllers. They must coordinate the movements of thousands of aircraft, keep them at ­safe distances from each other, direct them during takeoff and landing from airports, direct them around bad weather and ensure that traffic flows smoothly with minimal delays.

When you think about air traffic control, the image of men and women in the tower of an airport probably comes to mind. However, the air traffic control system is much more complex than that. Following are some equipment which used in air traffic controlling and how they are trained.

Air Traffic Control System Command Center (ATCSCC) - The ATCSCC oversees all air traffic control. It also manages air traffic control within centers where there are problems (bad weather, traffic overloads, inoperative runways).

Air route traffic control centers (ARTCC) - There is one ARTCC for each center. Each ARTCC manages traffic within all sectors of its center except for TRACON airspace and local-airport airspace.

Terminal radar approach control - TRACON handles departing and approaching aircraft within its space.

Air traffic control tower (ATCT) - An ATCT is located at every airport that has regularly scheduled flights. Towers handle all takeoff, landing, and ground traffic.

Flight service station (FSS) - The FSS provides information (weather, route, terrain, flight plan) for private pilots flying into and out of small airports and rural areas. It assists pilots in emergencies and coordinates search-and-rescue operations for missing or overdue aircraft.

ATC Tower:-

Every airport has a control tower. Here, air traffic controllers manage the traffic's time and order. This involves 'sequencing' for aircraft using the taxiways, runways, and the skies near the airport.

Air traffic controllers work from a tower because this vantage point lets them see the planes they manage and thus allows them to operate as efficiently and safely as possible. All air traffic control functions rely strongly on technology, especially in adverse weather conditions.

All airborne planes close to the airport are shown on a single radar screen, and the ground radar shows all traffic in the airport area to one-metre accuracy.

Aircraft and ground vehicles are permitted to use the taxiways and runways only after receiving clearance from air traffic control.

Thanks to the collaborative decision-making (CDM) method adopted at Helsinki Airport, aircraft wait at their gates with engines turned off until space is ready for them on the runway. This method makes air travel more efficient by enhancing the co-operation among the various parties involved in the process between the landing and departure of aircraft.

It enables the aircraft to proceed smoothly to takeoff right after being given clearance for taxiing and takeoff. This is an important factor, because the logistics requirements are tight: each year, up to 87,000 flights leave from Helsinki Airport.

 ATC Tower in New York City.

Duties Of Air Traffic Controller:

Air traffic controllers manage aircraft through all aspects of their flight with the priority of safety, followed by other aspects such as ensuring arrivals and departures are on time.

They use highly sophisticated radar and radio communication equipment to communicate advice, information and instructions to pilots.

Air traffic controllers are well known for working in control towers at airports, but the majority actually work in area control centres. They are responsible for the en-route stage of the aircraft, using radar to track its exact position, keeping it safe in the airspace and providing the most efficient route.

Approach controllers deal with instrument landing systems, which allow some planes to make automatic landings, and ensure that planes are placed in holding patterns when airports are busy. They take over from the area controllers as the aircraft is approaching the airport. They give initial clearance for the aircraft to approach the airport and put all approaching aircraft into a sequence to create the most efficient order for landing.

At the last stage, aerodrome controllers take over. They are the ones who are at the top of the control towers and they guide the pilots in to make a safe landing. The towers enable them to have good all round viewing of the aerodrome. They ensure that the aircraft gets to its parking stand safely and that those leaving the stands reach the runway safely. In some busy airports, the aerodrome controllers are divided into air control and ground control.

In addition to carrying out the same take-off and landing procedures as civilian air traffic controllers, air traffic controllers in the RAF also make sure the air bases are maintained and prepared for emergencies. They also communicate with civilian air authorities to ensure civilian aircraft can pass safely through their airspace. For further information, see Royal Air Force Careers .

Typical work activities:

Tasks may vary depending on whether you work as an area, approach or aerodrome controller, but they include:

• keeping radio and/or radar contact with aircraft;
• directing the movement of aircraft en route or at an airport;
• instructing aircraft to climb or descend and allocating final cruising level;
• providing information to aircraft about weather conditions;
• making sure that minimum distances are maintained between planes;
• handling unexpected events, emergencies and unscheduled traffic.

Duties specific for approach and aerodrome controllers include:

• controlling movements onto and off runways;
• handling the ground movement of planes around the terminals;
• handling the ground movement of vehicles around the airport.

Air Traffic Control Problems:-

Air travel has increased dramatically since the U.S. federal government deregulated the airline industry in the 1970s. However, the construction of new airports and runways has not kept pace with the increase in air traffic. This has put excessive pressure on the air traffic control system to handle the nearly 50,000 flights per day, a number projected to increase in the near future. To handle these flights and avoid delays and collisions, the FAA and NASA have developed modern software, upgraded existing host computers and voice communications systems and instituted full-scale GPS (global positioning system) capabilities to help air traffic controllers track and communicate with aircraft. The FAA is currently redesigning U.S. airspace to make more room for increased traffic. For example, the U.S. military has freed previously restricted airspace off the coast of North Carolina for use by commercial aircraft. These efforts should help ease traffic and minimize delays in the short term; however, increasing airport capacity by building new runways and airports is ultimately the way to handle the problem.

Intersecting contrails of aircraft over London, an area of high air traffic.

References:-

http://science.howstuffworks.com/transport/flight/modern/air-traffic-control5.htm

http://www.finavia.fi/en/news-room/magazine/2013-03/article/air-traffic-control--how-it-works/