How Air Traffic Control Works

How Air Traffic Control Works

This article serves as a repository of the content related to various aspects of air traffic control (ATC) that is available on SKYbrary. While some of the content can be of interest to air traffic controllers, the main purpose of this article is to provide a structured view on how ATC works to other professionals and aviation enthusiasts as well as to trainee air traffic controllers.

Communication Aspects

Air-ground communication is one of the most important aspects of air traffic control.

The Place of Air Traffic Control

Air Traffic Management (ATM) comprises the following:

  • Air Traffic Service. This is a general term encompassing:
    • Air Traffic Control (ATC). This is the main service provided by air traffic controllers and is divided into:
      • Aerodrome control service. This is focused on aircraft on the ground (the manoeuvring area of the aerodrome) or in the vicinity of the aerodrome (mostly the Aerodrome Traffic Circuit)
      • Approach control service. This service links the aerodrome control and the area control and is focused on the climb, descent and approach phases of the flight.
      • Area control service. This service is focused on the cruising part of the flight.
    • Flight Information Service (FIS). This service is performed in uncontrolled airspace
    • Alerting Service. This service is provided in order to inform the Search and Rescue (SAR) facilities of aircraft in distress.
  • Air Traffic Flow Management (ATFM) is intended to arrange traffic flows in such a way as to avoid congestion and reduce the risk of controller overload.
  • Airspace Management (ASM) is intended to organize the airspace so that it meets the needs of the users in the most optimal way.

Controller Positions

Air Traffic Controllers

There are three main types (ratings) of air traffic controllers. Within each type, different roles may be defined to address specific aspects of traffic demand or the airspace served.

  • Tower Controller is a person that provides air traffic control service at and in the vicinity of an aerodrome.
  • Approach Controller is a person that provides air traffic control for departing and arriving flights. They are the link between the tower controllers and the area controllers.
  • Area Controller (sometimes called en-route controller) is a person that normally serves the flights during the cruise phase.

Other Similar Positions

These positions do not provide ATC service but there are many similarities between them and air traffic controllers.

  • FIS Officer is a person that provides flight information service.
  • Assistant is a person that assists air traffic controllers by performing some routine tasks (e.g. certain coordinations or flight data exchange).
  • Supervisor is a person who is operationally responsible for the management of an ATS unit during a shift.

Working Position Organization

The information in these articles is relevant to all controller positions.

Controller Training and Competency

Before a person starts to provide ATC service, they must be properly trained and qualified.



The surveillance tools greatly enhance the controllers' situational awareness and allow them to handle more traffic without compromising safety.

ATM Systems and Support Tools

The automated systems combine data from different sources thus further enhancing the controllers' situational awareness. This leads to a great increase of capacity (i.e. the ability to safely handle multiple flights).


ATC Clearances

Air traffic controllers issue clearances and instruction to aircraft in order to separate them and to create and maintain an expeditious traffic flow.


One of the most important tasks of air traffic controllers is to provide separation, i.e. make sure that there is enough spacing between aircraft so that there is no risk of collision.

Conflict Detection and Solving

Prevention of collisions between aircraft is normally done by providing adequate separation. This is a two step process. First, the controller detects potential conflicting aircraft pairs. Then, appropriate measures are taken to resolve the conflicts.

Basic Controller Techniques

This subsection contains information on the basic techniques used by controllers in order to achieve the objectives of air traffic control.


Coordination with neighbouring ATC sectors and units is an integral part of air traffic control.

Articles Related to ATFM

Air traffic flow management aims to adjust traffic demand with the available capacity.

Articles Related to ASM

The main objective of airspace management is to ensure optimal use of the available airspace.

Further Reading


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