Communication, navigation and surveillance (CNS) are the main functions that form the infrastructure for air traffic management, [1] [2] and ensure that air traffic is safe and efficient. [3]
The CNS has the following three main functions.
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 and the ground based communication infrastructure of the ATM network (like the aeronautical fixed service). [2] For continental airspace, VHF (civil) and UHF (military) systems are used whereas for oceanic areas, high frequency systems and SATCOMs are used. [3]
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. [2] [4]
Surveillance systems are used by air traffic control to determine the position of aircraft. There are two types of surveillance systems:
Cooperative systems: Under this form of surveillance, systems on the ground (such as SSR) communicate with equipment (such as transponders) on board the aircraft to determine the position and other details of the aircraft. Aircraft information, which may include position from GNSS or other means is determined on board and then transmitted to ATC in response to interrogation. [2] [3] Other cooperative systems such as ADS-B rely on aircraft transmitting their position and other information without interrogation from the ground.
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. [2] [3]
Avionics are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform.
In telecommunication, 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. It is variously abbreviated as XPDR, XPNDR, TPDR or TP.
Air traffic control (ATC) is a service provided by ground-based air traffic 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 air 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.
Free flight is a developing air traffic control method that uses no centralized control. Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade. Its potential impact on the operations of the national airspace system is disputed, however.
A traffic collision avoidance system or traffic alert and collision avoidance system is an aircraft collision avoidance system designed to reduce the incidence of mid-air collision (MAC) between aircraft. It monitors the airspace around an aircraft for other aircraft equipped with a corresponding active transponder, independent of air traffic control, and warns pilots of the presence of other transponder-equipped aircraft which may present a threat of MAC. It is a type of airborne collision avoidance system mandated by the International Civil Aviation Organization to be fitted to all aircraft with a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or authorized to carry more than 19 passengers. CFR 14, Ch I, part 135 requires that TCAS I be installed for aircraft with 10-30 passengers and TCAS II for aircraft with more than 30 passengers. ACAS/TCAS is based on secondary surveillance radar (SSR) transponder signals, but operates independently of ground-based equipment to provide advice to the pilot on potentially conflicting aircraft.
ENAIRE is the air navigation manager in Spain and Western Sahara, certified for the provision of en route, approach and aerodrome control services. As a public corporate entity attached to the Ministry for Public Works, it is responsible for air traffic control, aeronautical information and the Communication, navigation and surveillance networks necessary so that air companies and their aircraft can fly safely, fluidly and in an orderly manner within Spanish airspace.
Secondary surveillance radar (SSR) is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the detected reflections of radio signals, relies on targets equipped with a radar transponder, that reply to each interrogation signal by transmitting encoded data such as an identity code, the aircraft's altitude and further information depending on its chosen mode. SSR is based on the military identification friend or foe (IFF) technology originally developed during World War II, therefore the two systems are still compatible. Monopulse secondary surveillance radar (MSSR), Mode S, TCAS and ADS-B are similar modern methods of secondary surveillance.
The air traffic control radar beacon system (ATCRBS) is a system used in air traffic control (ATC) to enhance surveillance radar monitoring and separation of air traffic. It consists of a rotating ground antenna and transponders in aircraft. The ground antenna sweeps a narrow vertical beam of microwaves around the airspace. When the beam strikes an aircraft, the transponder transmits a return signal back giving information such as altitude and the Squawk Code, a four digit code assigned to each aircraft that enters a region. Information about this aircraft is then entered into the system and subsequently added to the controller's screen to display this information when queried. This information can include flight number designation and altitude of the aircraft. ATCRBS assists air traffic control (ATC) surveillance radars by acquiring information about the aircraft being monitored, and providing this information to the radar controllers. The controllers can use the information to identify radar returns from aircraft and to distinguish those returns from ground clutter.
The Airports Authority of India or AAI is a statutory body, under the jurisdiction of Directorate General of Civil Aviation, Ministry of Civil Aviation, Government of India. It is responsible for creating, upgrading, maintaining and managing civil aviation infrastructure in India. It provides Communication Navigation Surveillance / Air Traffic Management (CNS/ATM) services over Indian airspace and adjoining oceanic areas. AAI is currently managing a total of 137 Airports, including 34 International Airports, 10 Customs Airports, 81 Domestic Airports and 23 Civil enclaves at Defense Airfields. AAI also has ground installations at all airports and 25 other locations to ensure safety of aircraft operations. AAI covers all major air-routes over Indian landmass via 29 Radar installations at 11 locations along with 700 VOR/DVOR installations co-located with Distance Measuring Equipment (DME). 52 runways are provided with Instrument landing system (ILS) installations with Night Landing Facilities at most of these airports and Automatic Message Switching System at 15 Airports.
An airport surveillance radar (ASR) is a radar system used at airports to detect and display the presence and position of aircraft in the terminal area, the airspace around airports. It is the main air traffic control system for the airspace around airports. At large airports it typically controls traffic within a radius of 60 miles (96 km) of the airport below an elevation of 25,000 feet. The sophisticated systems at large airports consist of two different radar systems, the primary and secondary surveillance radar. The primary radar typically consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. It detects the position and range of aircraft by microwaves reflected back to the antenna from the aircraft's surface. The secondary surveillance radar consists of a second rotating antenna, often mounted on the primary antenna, which interrogates the transponders of aircraft, which transmits a radio signal back containing the aircraft's identification, barometric altitude, and an emergency status code, which is displayed on the radar screen next to the return from the primary radar.
The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting. In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.
An air navigation service provider (ANSP) is a public or a private legal entity providing Air Navigation Services. It manages air traffic on behalf of a company, region or country. Depending on the specific mandate an ANSP provides one or more of the following services to airspace users
A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist in identifying them on air traffic control radar. Collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.
The aviation transponder interrogation modes are the standard formats of pulsed sequences from an interrogating Secondary Surveillance Radar (SSR) or similar Automatic Dependent Surveillance-Broadcast (ADS-B) system. The reply format is usually referred to as a "code" from a transponder, which is used to determine detailed information from a suitably equipped aircraft.
Automatic Dependent Surveillance–Broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation. ADS–B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.
The State Secretariat of Civil Aviation is an agency of the government of Cambodia in-charge of civil aviation including airports in the country. It is headquartered in the capital Phnom Penh. The SSCA oversees the operation of national airports and air traffic management system in Cambodia. In 2000, it granted lease to SAMART Corporation to operate and upgrade the country's air traffic control and air navigation system under a long-term concession. The Secretary of State in charge is Mao Havannall.
The Civil Aviation Authority of Fiji (CAAF) is the national aviation authority in the Republic of Fiji and is responsible for discharging functions on behalf of the Government of Fiji under the States responsibility to the Convention on International Civil Aviation, also known as the Chicago Convention on International Civil Aviation Organization (ICAO). CAAF regulates the activities of airport operators, air traffic control and air navigation service providers, airline operators, pilots and air traffic controllers, aircraft engineers, technicians, airports, airline contracting organisations and international air cargo operators in Fiji.
Georgian Civil Aviation Administration is the Aviation Authority which controls all the aviation affairs on the territory of Georgia. GCCA HQ is at Tbilisi International Airport in the city of Tbilisi.
BULATSA is the Bulgarian Air Traffic Services Authority, a branch of the Bulgarian Civil Aviation Administration responsible for air traffic management within Bulgaria's airspace.
Aireon is an American company based in McLean, VA. Founded in 2011, it manufactures, deploys, and operates a global aircraft tracking and surveillance system utilizing satellite-based receivers to monitor the existing ADS-B transmissions of aircraft, for global air traffic surveillance.
