Maastricht ATC Conference 2006: ADS-B trial could precede Asia network

 - September 21, 2006, 4:55 AM

Airservices Australia CEO Greg Russell made the trip to Maastricht to sign a partnership agreement with Francesco Violante, his counterpart at datalink service provider SITA, that will see the two organizations jointly support a trial in Indonesian airspace of an ADS-B network that could be a prelude to a proposed southeast Asia-wide surveillance net.

Airservices is already implementing an ADS-B network of 28 ground stations to provide upper airspace surveillance over Australia. In October 2004 the air navigation service provider (ANSP) and SITA agreed to explore the possibility of such a network, which would combine the ANSP’s practical experience of implementation, including aspects such as controller training and upgrades to ATC automation, with SITA’s existing VHF network in the region.

In addition to providing the telecommunications network that would be needed to support the plan, SITA has the ground sites and experience of delivering a general datalink service that can be applied to an ADS-B service, including functions such as a 24/7 help desk, customer support, and billing and reporting systems. “We didn’t invent ADS-B,” Russell commented, “but we hope we can help speed up its introduction.”

ADS-B ground stations are typically much less complex–and consequently less expensive and less demanding of maintenance, power, accommodation and other resources–than traditional surveillance radars. As well as offering potential savings when it replaces conventional radar technology, the system can be particularly useful in areas where there is no radar coverage and where it would be uneconomic, physically impractical or politically impossible to install ground radars. The partners are looking at other parts of Asia as well as Africa and the Middle East, where there is a lack of surveillance technology.

The proportion of aircraft that are already equipped with suitable transponders using Australian airspace has surpassed 30 percent and is increasing steadily, partly as a result of a European mandate requiring that aircraft be equipped for mode-S by next year.

The addition of a GPS feed and appropriate software is all airliners need to add ADS-B capability to a mode-S fit, and because the better position information should enable separations to be reduced from the 30 or 60 nm applied in procedural airspace where there is no surveillance. Access to preferred trajectories and fuel-efficient routes could be an incentive for operators to equip their aircraft.

Equipping Smaller Aircraft

Airservices Australia is also encouraging the development of low-cost avionics for general aviation aircraft. The move has proved contentious, Russell said, but if ADS-B surveillance is to be extended to lower airspace the issue of the 12,500 general aviation aircraft that fly through it will have to be addressed.

“There has been no decision yet on how to handle it, or on a mandate for equipment or who would pay for it,” Russell said. However, manufacturers have been consulted as part of an industry-wide cost-benefit analysis looking at alternative ways of providing surveillance.

One finding has been that smaller aircraft can use mode-S extended squitter and do not need alternative datalinks such as the universal access transceiver (UAT) used for general aviation ADS-B in the U.S. or the VDL Mode 4 some sections of the industry promote.

Airservices has also developed a cross-industry business case that takes into account the shift in cost of surveillance, with ground installations becoming less expensive but requiring operators to add equipment to their aircraft. Looking at the next few years, it compares the cost of replacing old radars and adding new ones with the cost of fitting avionics and installing ADS-B ground stations.

Either way, the reasoning goes, the airlines will end up paying, and since they are in favor of moving to ADS-B, Airservices is looking at the possibility of using some of their savings to subsidize general aviation equipment. The airlines still end up with reduced charges, and Airservices says the cost-benefit business case has proved robust, but the idea of transferring the cost remains controversial.

The proposed ADS-B network in Southeast Asia could represent a significant safety improvement. States in the region tend not to exchange surveillance data, with the result that aircraft entering a new flight information region (FIR) can appear suddenly in a position that does not correspond to the filed flight plan.

The Philippines could be the next site for an operational trial, and the partners emphasize that they do not want to install isolated pieces of hardware that are not integrated into how ANSPs work. “The trial in Indonesia is not a test of the technology,” Violante said. “It is a test of a new business model to see whether a service-provider model will fly in this industry.”

The Indonesian trial 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 Indonesian cities 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.