The objective of the SALSA project is to conduct studies to prepare for the introduction of lower separation distances (separation minima) in non-radar airspace (NRA). In addition, recommendations will be made in SALSA for reduced separation minima and the required design of the satellite-based ADS-B air traffic surveillance system. These recommendations will be discussed with air-traffic committees and air traffic control authorities with responsibility for transatlantic routes, and other activities necessary to support the system's introduction will be identified.
An important theme in the research and development work carried out in SESAR 2020 is the future use of Automatic Dependent Surveillance – Broadcast (ADS-B) for air traffic surveillance. The ADS-B mandate which applies across Europe sets out that from 2020 all aircraft over 2.5 tonnes in takeoff weight or faster than 250 knots true air speed must be equipped with ABS-B transmitters. The same applies in the US with the "ADS-B Final Implementation Rule" published by American air traffic control authority the FAA. Aircraft equipped with ADS-B automatically transmit position, speed, altitude, callsign and other data every half second enabling more precise surveillance with a higher update rate and considerably lower costs. At the same time, air traffic control authorities plan to supplement the existing radar network with ground-based ADS-B receiver stations to begin with.
Since 2008 research work on the satellite-based reception of ADS-B signals has been taking place at DLR with the objective of enabling tightly knit surveillance of the airspace even in transoceanic airspace or in continental areas with weak infrastructure. The DLR project "ADS-B over Satellite" which ran from 2011 to 2014 proved for the first time, as part of the ESA satellite mission PROBA-V, that the reception of ADS-B signals by LEO satellites is technically possible. Further proof was then provided with the cube satellites GOMX-1 and GOMX-2 belonging to Danish company GomSpace and with the satellite Tianwang-1A (SECM-1) of the Chinese Tianwang1/STU-2 mission, carried out by the Nanjing University of Aeronautics and Astronautics and the Shanghai Engineering Centre for Microsatellites (SECM).
Aireon LLS, a joint venture from IRIDIUM, NaV Canada and other companies and air traffic control authorities, is tackling the design of a global constellation of satellites equipped with ADS-B receivers based on the IRIDIUM-Next satellite communications system and making available services for satellite-based air traffic surveillance, the tracking of aircraft and emergency alerts in case of unexpectedly terminated flight tracks. The system is expected to be operational from 2020.
It is all the more important then, that not only the technical possibilities and requirements of a satellite-based airspace surveillance system using ADS-B but also the operational aspects significant for the introduction and operation of the system are investigated, not least with a view to existing and possible future international standards.
An improvement in flight safety, faster location of accident sites and a more efficient use of airspace, particularly on the transatlantic routes, are the operational objectives for the introduction of satellite-based airspace surveillance. The latter can be achieved by lower separation limits on all flight routes.
In the SALSA project the current systems and procedures for air traffic surveillance and existing standards from EUROCAE, RTCA and ICAO will be investigated and suggestions will be developed for suitable future standards for satellite-based air traffic surveillance using ADS-B and the application of reduced separation minima which could be used as the basis for later certification.
The objective of the project is to create the conditions required for the introduction of lower separation minima on transoceanic flight routes. Of particular interest here are the transatlantic routes from Europe to America which are already showing considerable traffic density during morning and evening peak periods. The current normal separation minima of 50 to 80 nautical miles (1 nautical mile is equivalent to 1852 meters) would be reduced to 15 to 30 nautical miles without affecting flight safety; this would enable more efficient use of airspace as well as increasing flexibility as soon as existing flight routes have to be changed due to storm fronts building.
Airbus Defence & Space United Kingdom (coordinator)
Airbus Defence & Space France
Airbus Defence & Space Germany
Redu Space Services