The Asia/Pacific region is pioneering the large-scale deployment of automatic dependent surveillance-broadcast (ADS-B), a technology that promises to replace the traditional secondary surveillance radars (SSR) which are commonly used to track en-route air traffic and supplement the information provided by primary radars in terminal areas.

ADS-B ground stations are typically much less complex, and consequently less expensive and less demanding of resources such as maintenance, power and accommodation than traditional surveillance radars. As well as offering potential savings when it replaces conventional radar technology, the technique can be particularly useful in areas where there is no radar coverage and where it would be uneconomic or physically impractical to install ground radars.

There have been many trials of the technology, and Australia has already implemented ADS-B surveillance of its upper airspace using a network of 28 ground stations supplied by Thales (Stand A521). The proportion of aircraft equipped with suitable transponders is also increasing steadily, partly as a result of a European mandate requiring that aircraft be equipped for mode-S by 2007. The addition of a GPS feed and appropriate software is all airliners need to add ADS-B capability to mode-S, and air traffic control agency Airservices Australia is encouraging the development of low-cost avionics for general aviation aircraft.

Other countries in the region, from Thailand and Japan to New Zealand, are also planning trials as a prelude to operational systems. And Airservices, in conjunction with aeronautical telecommunications and IT specialist SITA, is proposing an innovative approach to the provision of surveillance information.

“The technology has the potential to provide seamless airspace from Australia to India,” commented Airservices CEO Bernie Smith. “It also gives us the means to introduce future air traffic management concepts, including flexible aircraft tracking, and will significantly enhance the safety and capacity of regional upper level airspace.”

Now the partners are supporting Indonesia in a trial ofthe technology. Akhil Sharma, SITA’s director Aircom business development, said Airservices is bringing its practical experience of implementation, including areas such as controller training and upgrades to ATC automation, and in preparing the necessary safety cases.

SITA already has a VHF network throughout the region. As well as providing the telecommunications network that would be needed to support the scheme, it has the ground sites and 20 years’ experience of delivering a general data link service that can be applied to an ADS-B service, including such functions as a 24/7 help desk, customer support, and billing and reporting systems.

States in this region tend not to exchange surveillance data, Sharma pointed out, with the result that aircraft entering a new flight information region (FIR) can appear suddenly in a position completely different from where they should be according to their flight plan. SITA believes that its neutral status as an airline-owned entity can enable it to pioneer the exchange of data between states.

Airservices and SITA are currently supporting an ADS-B trial by Indonesia that illustrates the attractions of the approach. It involves the installation of ground stations at five sites. One is on the Australian territory of Christmas Island, 1,400 nm northwest of Perth in Indonesian airspace in the Indian Ocean. Another, Natuna Island in the South China Sea to the northeast of Singapore, is part of Indonesia but within the Singapore FIR. The other three are at sites in Pangkalan Bun, Bali and Kupang. So Indonesia and Singapore alike could benefit from data collected at sites that are within their airspace but where they could not provide their own ground stations.