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Exploratory actions on Automatic Dependent Surveillance (ADS) for European air traffic management systems


- A Common Technical Specification (CTS) was produced in February 1995. This defines the interface and functional ADS standards for the project, the first detailed definition of an ATN-based interface. This Specification is also being used as a baseline for other trials such as the North Atlantic Unified Trial (NUT).
- Avionic ADS unit software for UK national trials was upgraded to the CTS standard. Tests between the ground-based ADS equipment (ADSE) test rig, via the satellite link, to the Eurocontrol Trials ATN Router (TAR) and the NATS ATC Ground Segment were completed.
- ADS avionics units have been developed by Racal (for the 747-400 aircraft) and Sextant (for Airbus A340).
- Integration testing between the EURATN Router and the Eurocontrol TAR is complete.
- Integration testing between ADSEs in ground-based test rigs, the ATN Routers and both Ground Systems has been completed.
- A BA Boeing 747-400 and a KLM Boeing 747-400 were fitted with ADSEs during January 1996 and communicated simultaneously via datalink to two ground stations during scheduled flights. Other aircraft from KLM, Lufthansa, Air France and BA have also been fitted with ADSEs. Trials data is being collected during regular commercial flights. An ADSE has also been installed in NLR's Cessna Citation aircraft which will be used to perform dedicated flights to investigate specific issues which cannot be explored by passenger aircraft in commercial service.
- A Performance Assessment Plan has been developed for the analysis of trials data. This describes the analysis process and the software tools available to support the trials.
- The basic set of software for the analysis tools has been developed and tested.
- The cost-benefit study has so far undertaken, and reported on, a literature review and airline consultation.
The overriding concern for all air traffic control (ATC) systems is safety. Deconfliction of aircraft, i.e. ensuring safe separation, is the primary responsibility. Uncertainty in the knowledge of aircraft position can lead to increased separation, reducing the capacity of ATC systems.

Radar is used extensively and its performance is no longer the limiting factor for separation standards. However, radar has a principal drawback: it has only limited range. Satellite technology along with the concept of Automatic Dependent Surveillance (ADS), a technique that uses on-board systems to transmit an aircraft's position automatically to ATC, offers a capability to pass position reports when aircraft are out of radar and VHF radio range. This is particularly relevant to oceanic areas or sparsely populated regions with minimal existing ATC infrastructure.

It is necessary to establish a communication topology to support ATC data link applications, and the ADS application must be supported by a communication system compliant with appropriate standards such as Aeronautical Telecommunications Network (ATN).

The ADS Europe project is the first ADS trial involving 'live' aircraft using communications protocols compatible with the ATN, together with a representative ground network.

The contract was placed to undertake initial development of these systems and infrastructure, and to obtain statistics for important parameters such as message transmission accuracy, integrity, timeliness, reliability and maintainability.

Planned future work and results

- The data collection and analysis phases of the trial will continue with aircraft flying with operational ADSEs.
- Remaining activities in cost-benefit are to collect costs from airlines and trials participants and to create the database which will be used to present and analyse these costs.
- The final report will be prepared for submission to the Commission in December 1996.

Exploitation potential and plans

Exploitation of ADS depends on availability of reliable data from trials to prove that the concept is technically viable and reliable, the establishment of favourable cost-benefit results, and the dissemination of this information.

The ADS Europe trials results will be used to support validation of the relevant ICAO standards for ATN, ADS and AMSS. This is required to support the planned operational introduction of systems based on these standards in the North Atlantic region in a 1998/99 timeframe.

The important aspect of dissemination of this information has been addressed through a defined publicity strategy, including key publicity events:

- first 'trial' flight in January 1996: updated single sheet brochure and article to selected magazines
- ATC '96, Maastricht on 27-29 February 1996: poster display and brochure
- UK NATS "Symposium 96", Botley on 23-24 April 1996: technical paper/ presentation
- live demonstration during IATA Seminar on ATN held at Eurocontrol on 23-25 April 1996
- demonstration at Farnborough International '96 during 2-8 September 1996.


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Call for proposal

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Funding Scheme

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Civil Aviation Authority (CAA)
Caa House 45-59 Kingsway
WC2B 6TE London
United Kingdom

Participants (10)

Air France
United Kingdom
Heathrow Airport
TW6 2JA London
United Kingdom
France Telecom
Racal Avionics
United Kingdom
Bushey Road Raynes Park
SW20 0JW London
75 Rue La Boetie
Sextant Avionique SA