Aviation Safety: Operational Trial of Advanced Surveillance Enhanced Procedural Separation using Space-Based Automatic Dependent Surveillance-Broadcast

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ICAO’s Planning and Implementation Regional Groups (PIRGs) were established by ICAO’s Council to ensure the continuous and coherent development of the regional air navigation plans and to monitor and foster their implementation. A prime example of the work of a planning and implementation regional group involves the use of technology to further improve safety and efficiencies. The Programmes Coordination and Implementation (PCI) Section within ICAO’s Air Navigation Bureau (ANB) is responsible for coordinating the PIRG and Regional Aviation Safety Group (RASG) activities in the ICAO Regions.

It is through the work of PIRGs, which serve as ICAO regional planning engines, that the Space-Based Automatic Dependent Surveillance-Broadcast (SB ADS-B) is being introduced. This trial service, which will begin on 28 March 2019, will enhance air traffic controllers’ abilities to provide operators with more planning and tactical options in oceanic airspace. This will include greater flexibility for severe weather avoidance, requests and approval of new oceanic routes, optimized speed, and requests for, and approval of, flight level changes.

The Space-Based ADS-B ATS surveillance system will consist of a constellation of the Low Earth Orbiting Satellites (LEOS) hosting ADS-B receivers. A satellite will receive ADS-B data that includes position, velocity and altitude from an aircraft, which is then routed through other satellites and down-linked to a satellite operation ground station where it will be forwarded to Air Navigation Service Providers (ANSPs) and/or aircraft operators.

ADS-B is automatic so no flight crew or air traffic control officer (ATCO) action is required for the information to be transmitted. It is considered dependent surveillance because the surveillance type information depends on the information from the aircraft’s navigation system. The ADS-B OUT systems broadcast aircraft parameters such as identification (24-bit address and flight identification as per the flight plan), position (latitude, longitude and pressure altitude), 3-D velocity and position integrity, via a broadcast-mode data link. The aircraft identification information is broadcast every five seconds while aircraft position and velocity data is typically broadcast twice per second.

Impact on aviation

The SB ADS-B surveillance will facilitate the application of Advanced Surveillance Enhanced Procedural Separations (ASEPs) between suitably equipped flights, resulting in a significant increase in airspace capacity, particularly in areas where there is a high volume of traffic, which will allow more flights to operate within their optimum flight profiles. New airspace capabilities will assist to reduce fuel burn with the associated environmental benefit of the decreased greenhouse gas (GHG) emissions.


The expanded ATS surveillance coverage in the North Atlantic (NAT) airspace will enable more efficient use of airspace, increase fuel savings and enhances safety, as compared to the services and separation standards that can be provided in the current non-surveillance environment. The Air Traffic Control (ATC) in the NAT region will be enhanced by the real-time availability of aircraft positioning. If successful, this may be expanded to other oceanic areas through the PIRG mechanism of information sharing.


About the author

 Herman Pretorius is a Technical Officer, Safety Programmes Coordination and Implementation Section (PCI) at ICAO Headquarters in Montreal. Prior to joining ICAO in 1999, he was employed by the South African Civil Aviation Authority in Pretoria. He is a fully qualified Air traffic Controller and held fixed wing and helicopter pilot licenses.