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A meeting hold in Copenhagen in the middle of last week marked the formal launch of the North European ADS-B Network (NEAN) project which is one of a series of ADS/STDMA-related trials being funded by the European Union.

The ECU 4 million NEAN project will involve the civil aviation administrations of Denmark, Sweden, and the UK (Safety Regulation Group); Germany's Deutsche Flugsicherung (DFS) air traffic services provider; as well as Lufthansa, Scandinavian Airlines, and the Swedish commuter carrier, Golden Air. The European Commission's Transport Directorate (DGVII) will provide ECU 2 million worth of funding, with the participating states providing the rest.

The three-year programme will last until September 1998 and actual flight trials are expected to begin in four to six weeks.

"The objective of the trial is to try and demonstrate the benefit of ADS systems to users," said Bo Redeborn, Manager Air Traffic Management with the Luftfartsverket, the Swedish Civil Aviation Administration. "We will try to do that by showing the benefits of situational awareness between pilots and drivers, improved surveillance by ATC, ground movements monitoring, ground-air date link, air-air data link, and networking on the ground, all based on ADS-B. The aim is to develop and validate the technology for ATM in the wider view, and to address the certification issue of a system like this since we do not have anything in operation at the moment that would directly compare with this."

The important elements of this particular trial, according to Redeborn, are the transmission of ADS-B reports via VHF data link (STDMA), and the connection of base stations on the ground into a large network in order to generate a consolidated surveillance picture over a large area.

Other aims of the trial will include the development of a cost data base, studying the relationship with ATN, standardisation issues, etc.

For the purposes of the trial, five ground stations in Germany (Berlin, Bonn, Braunschweig, Bremen, and Frankfurt), three in Denmark (Alborg, Bilund, and Copenhagen), and six in Sweden (Stockholm / Arlanda, Stockholm / Bromma, Jönköp!ng, Gothenburg / Landvetter, Maimö / Sturup, and Norrköping) will be connected into a single network.

"That set-up would probably give us a consolidated surveillance picture covering more than one third of the area of Western Europe above 5.000 ft, so it will give us substantial coverage range," said Redeborn.

Although there will be just three aircraft initially participating in the trials, others are expected to join the programme soon. Maersk of Denmark and Braathens of Norway have already had discussions with the NEAN team.

The aim is to get as wide a mix of aircraft as possible and to link up with other EC-funded trials programmes, including the DGXIII-funded Faraway (Italy), Magnet B (France) and Supra (Spain) which have some complementary objectives.

"We believe the network is a platform to address Integrity issues and to distribute surveillance data to ATC," said Redeborn.

The base stations will need to be equipped with a VHF antenna, a GNSS differential receiver, and a GNSS transponder configured in the ground station mode. In addition there will be a computer or router that will administer the communications and connect them on existing telecommunications networks. In order to generate the consolidated surveillance picture, concentrator units will be used at certain locations to combine identical master and slave position reports into a single report and thereby avoid overloading the system.

Ground installation requirements are therefore minimal, simple, and inexpensive, according to Redeborn, All six stations in Sweden have now been completed, as have two - Bilund and Copenhagen - in Denmark. The rest will follow shortly.

The aircraft will be equipped with a GNSS transponder. At present, two aircraft - a Golden Air Saab 340 and an SAS F28 - have been equipped, although the transmission of position data is not expected to begin for another four to six weeks. The two aircraft will also be equipped with a selector which is an migrated computer/display which will facilitate position date feedback to the pilots and allow inputs, outputs, loggings, recordings, etc. The selector is necessary for aircraft not equ'ipped with an FMS. Lufthansa will be contributing a glass cockpit Airbus airliner to the trials and is therefore understood to be considering a more sophisticated solution for integrating data derived from the GNSS-transponder into the digital display.

"The trials represent the first time that this equipment - which is based on the Swedish-developed Global Positioning and Communication (GP&C) system - has been incorporated in a trial done within a European Union-financed project. It will also be the first time that the equipment will be carried on a regular basis and used by a commercial airliner flying with payload," said Redeborn.

Preparation for the project has been in progress since last November, and the rest of the programme is divided into a number of work packages The first work package includes all the installation work and is due for completion in September this year.

A second work package, from September 1996 to August 1997 should see more aircraft added to the programme and existing equipment replaced and modiffed in line with ICAO SARPS.

Work package 3.1 will involve development of the network - connecting the independent or autonomous base stations into a consolidated network.

From September 1997 to September 1998, a further work package will demonstrate the application (free flight concept-related, cockpit display of traffic information, airborne separations, etc).

Work package 5 looks at certification Issues. It starts now and continues for the rest of the year to ascertain what is required to establish a certification process. Another work package will involve data analysis and reporting.

"If things go the way we expect, there might be in the order of 40,000 flights conducted over this entire three year period and which means it should be possible to collect a substantial amount of data," Redeborn said.

Formal approval of the DGVII financing for the project came through in December last year, allowing the mid January kick-off.