Eurocontrol to examine Aireon space-based ADS-B on cost, performance & network benefits

Eurocontrol experts will start analysing whether space-based surveillance makes sense in terms of both performance and cost.

In its Skyway publication, the European air navigation safety agency said it will start using  data from the Iridium NEXT satellites to understand whether and how space-based Automatic Dependent Surveillance-Broadcast (ADS-B) operations might be implemented to improve surveillance and other services over Europe.

Aireon, the space-based ADS-B service provider using Iridium NEXT satellites, will provide the technology enabler for a new global aircraft tracking and surveillance service. The first 10 satellites were launched in January, with a further 10 in June; the plan is, through a series of eight launches in total, for 75 Iridium NEXT satellites to be operational in low-Earth orbit by mid-2018, with 66 making up the operational constellation.

Eurocontrol said the potential benefits of space-based ADS-B are theoretically many and wide-ranging. It will, for the first time, give air navigation service providers (ANSPs) a detailed surveillance picture of traffic flying over oceans and remote airspaces while providing an additional layer of surveillance redundancy in medium- and high-density areas currently covered by radars, multilateration systems and ground-based ADS-B stations. In areas where there was no surveillance before, this should allow for more direct routings, lower separation minima and reduced environmental impact.

There are however two key elements which Eurocontrol said need to be properly understood before it becomes clear how space based ADS-B can be integrated within the current surveillance network — performance and cost. The agency said it will also be assessing potential benefits space-based ADS-B could bring to its activities, including Network Manager (NM) operations.

“We have been working on ADS-B since early 2000 for the co-ordination of ADS-B deployment and supporting its implementation in Europe, always keeping in mind the need for global interoperability,” said Christos Rekkas, who heads Eurocontrol’s surveillance modernisation section and its surveillance focal point for the Single European Sky ATM Research (SESAR) programme.

“I think from the moment space based ADS-B came in a few years ago, we were interested in the sense that it aims to extend significantly surveillance coverage, to make it global. For the time being, our main interest has been to get the data and analyse it for our own purposes, our own use, with the first use-case being flow management,” he said.

The current surveillance network in Europe is very extensive, according to Eurocontrol, with hundreds of radars, dozens of multilateration systems and around 800 ADS-B ground stations installed. When European ANSPs look to replace ageing ground-based systems, space-based ADS-B will offer a potential source of detailed information on aircraft flying in remote or oceanic areas, beyond the range of ground-based surveillance equipment.

“There are many countries with radar or multilateration infrastructure who are considering the use of ADS-B as a complementary surveillance layer,” said Rekkas. “I think, from what we know so far, space-based ADS-B will position itself as a player not only in oceanic but also in continental airspaces. It will be a complementary layer, a gap filler or contingency system, to radar or multilateration in the cases where ground-based ADS-B is not yet in place. So, depending on pricing and performance, we see it playing a significant role, though with major differences between its use in continental and oceanic areas.”

Aireon has already signed bilateral agreements for investigation of the system or provision of data services with several ANSPs, including NATS, DSNA, DFS, Isavia, ENAIRE, Naviair, Nav Portugal and the Irish Aviation Authority.

In terms of surveillance system performance, Eurocontrol said it will be necessary to see whether space-based ADS-B will have the quality — for example, probability of update, latency, accuracy and integrity — to provide five-mile separations required for a complementary role to radar in European airspace.

Its own surveillance team already has experience in this area through its work in comparing ground-based ADS-B data with trajectories reconstructed from real multi-radar data. With space-based ADS-B data, says Rekkas, the logical methodology would be to compare the new data with multi-radar-based trajectories, ground-based ADS-B and multilateration data.

This would allow surveillance experts to explore a range of performance characteristics such as detection probability, latency, accuracy, missing data and the effect of interference from multiple sources. In a performance-based context, the ultimate goal will be to assess whether the overall surveillance system performance will be equal to or better than the required one in a particular type of environment, such as low-density or high-density areas and the separation minima applied.

In terms of cost, Eurocontrol said analysis will be needed to compare cost-per flight hour charges which the system providers intend to agree with individual ANSPs, with respect to the cost of buying, operating and maintaining radar or other surveillance systems. But the cost comparisons will be user-specific as the system providers intend to adopt a variable pricing policy, for example based on the traffic density managed by the ANSP. Much of the information is commercial in confidence.

Eurocontrol said it has already begun considering the investigation of space-based ADS-B data benefits and cost for Network Manager flow management services.

“We would like to have access to information about aircraft flying in areas where, until now, it has been difficult to get reliable data,” said Rekkas. “We could increase the predictability of incoming trajectories and thereby increase the performance of the Network, because we could reduce the uncertainty in our inputs from these parts of the airspace. The other possibility is to use the information in the event of incidents or distortions of the system. If we needed information from a particular place outside our operational area, this could be visible.”

He said that as the Network Manager is a “data hungry”, multi-source operation; all relevant information on trajectories, planned and actual, can be used to improve the performance of the overall system.

He added that space-based ADS-B could also have a major role to play in aircraft flight tracking. Eurocontrol chairs the International Civil Aviation Organization (ICAO) advisory group working on developing a global flight-tracking system which calls for all flights to be tracked every 15 minutes; the typical update rate of space based ADS-B, according to the system developers, is every few seconds.

“The potential benefits of space-based ADS-B are therefore many. But there is still further work to do before these benefits and associated costs can be quantified throughout the continent, providing the independent data-sets required for all ANSPs to make long-term surveillance investment decisions.”

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