Communication, navigation and surveillance (CNS) are the main functions that form the infrastructure for
air traffic management 334x334px,
Air traffic management (ATM) is an aviation term encompassing all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome, consisting of air traffic services (ATS) including air t ...
,
and ensure that air traffic is safe and efficient.
Functions
The CNS has the following three main functions.
Communication
Communication, i.e.
aviation communication, refers to communication between two or more aircraft, the exchange of data or verbal information between aircraft and
air traffic control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...
and the ground based communication infrastructure of the ATM network (like the
aeronautical fixed service
The aeronautical fixed service (AFS) is a telecommunication service between specified fixed points provided primarily for the safety of air navigation and for the regular, efficient and economical operation of air services. ("Air service" means an ...
).
For
continental airspace,
VHF (civil) and
UHF (military) systems are used whereas for
oceanic areas,
high frequency systems and
SATCOMs are used.
Navigation
Navigation, i.e.
air navigation, refers to the process of planning, recording, and controlling the movement of an aircraft from one place to another by providing accurate, reliable and seamless position determination capability.
Surveillance
Surveillance systems are used by air traffic control to determine the position of aircraft. There are two types of surveillance systems:
Cooperative systems
Cooperative systems: Under this form of surveillance, systems on the ground (such as
SSR) communicate with equipment (such as
transponder
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''.
In air navigation or radio frequency identification, a flight trans ...
s) on board the aircraft to determine the position and other details of the aircraft. Aircraft information, which may include position from
GNSS
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
or other means is determined on board and then transmitted to
ATC in response to interrogation.
Other cooperative systems such as
ADS-B rely on aircraft transmitting their position and other information without interrogation from the ground.
Non-cooperative systems
Non-cooperative systems: Under this form of surveillance, systems on the ground (such as
PSR) are able to locate the aircraft and measure its position from the ground by transmitting pulses of radio waves which reflect off the aircraft's hull.
See also
*
Air traffic management 334x334px,
Air traffic management (ATM) is an aviation term encompassing all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome, consisting of air traffic services (ATS) including air t ...
References
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Air traffic management 334x334px,
Air traffic management (ATM) is an aviation term encompassing all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome, consisting of air traffic services (ATS) including air t ...