On 14 January, 2017, a SpaceX rocket powered the first ten satellites of a global space-based automatic dependent surveillance broadcast (ADS-B) system into orbit.
While the system won’t be operational until 2018, there are high hopes that space-based ADS-B will fulfil a number of industry needs.
Surveillance is the main driver. Some 70% of the Earth—most especially oceanic and remote airspace—has no air traffic surveillance coverage today. Ground-based navigational aids for air traffic management aren’t available.
ADS-B is a bells and whistle version of the conventional transponder
The result is that, in these areas, aircraft separation is maintained through procedural standards—in effect spacing aircraft further apart than necessary for safe operations.
This has a negative impact on airspace capacity and efficiency, which the Iridium network of satellites hosting the space-based ADS-B system is aimed at addressing.
An aircraft with ADS-B capability broadcasts its position in real time, enabling air navigation system providers (ANSPs) to exactly pinpoint the aircraft’s location.
“ADS-B is a bells and whistle version of the conventional transponder,” explains Cyriel Kronenburg, Vice President, Aviation Services at Aireon, the space-based ADS-B technology provider.
“It enables a far greater amount of information to be sent out, including speed, flight plan, and much more.”
Ground-based ADS-B is already operational in a number of areas, but as with conventional radar, is generally unavailable in oceanic and much remote airspace. Space-based ADS-B will address this gap by offering coverage around the globe.
We’re going to know where the aircraft is all the time and that provides the opportunity to fly closer together
In theory, this should enable more aircraft to operate safely in the same amount of airspace than currently is possible.
“Reduced separation comes from having surveillance where we didn’t have it before,” Kronenburg says.
“If we didn’t know where the aircraft was then the industry had no choice but to follow procedural separation…. Now we’re going to know where the aircraft is all the time and that provides the opportunity to fly closer together while improving safety at the same time.”
There are also implications for improved tracking of aircraft, which ICAO has mandated from November, 2018 (see GlobalBeacon panel).
The technical details
The satellites hosting space-based ADS-B belong to the Iridium Low Earth Orbit system. Each satellite will be extensively tested for about two months before being handed over by Iridium to the ADS-B technology provider, Aireon, for verification of on-orbit technical specifications.
Aireon’s own rigorous assessment will also take a couple of months before the system is ready for operation. Only then will older, first generation Iridium satellites be de-orbited.
The global nature of space-based ADS-B means many other sectors will be covered that haven’t had surveillance before
Further launches to complete the global network are scheduled for the remainder of 2017 and early 2018, subject to a number of factors, including the correct weather window.
It is anticipated that the network will be complete in the first quarter, 2018. ADS-B will go live with launch customers, NATS and NAV CANADA—the air navigation service providers (ANSP) for the United Kingdom and Canada respectively—soon after.
Iceland are among the other ANSPs contracted, which completes the North Atlantic picture all the way up to the arctic.
But the global nature of space-based ADS-B means many other sectors will be covered that haven’t had surveillance before.
The Seychelles is also signed up, for example, which accounts for an important part of the Oceanic gap between Africa and India where some of the wreckage of MH 370 has been found.
“For airlines, it is about flying where you want to fly and not where you are told to fly,” Kronenburg continues. “Oceanic and remote airspace will become like continental airspace. Dynamic re-routing to avoid weather, for example, will be possible no matter where an aircraft is located.
"And because most of the modern fleet have ADS-B-capable avionics, pilots won’t notice much difference.”
It is about flying where you want to fly, and not where you are told to fly
It is estimated, for example, that about 90% of the fleet flying across the North Atlantic already have ADS-B capability.
The new technology could also be a boon to air navigation service providers (ANSP). ADS-B can take the place of one of the independent radar layers.
Radars are very costly to purchase and maintain, so there may be savings in opting for space-based ADS-B and associated communication enhancements.
The space-based model could also provide a handy kick start to ANSPs sharing harmonized data on a global level. This will make an important contribution to flow management, which makes it easier to handle traffic, especially in times of high demand.
“Few technologies exist today that by simply reimagining their implementation can have such a dramatic, positive impact on safety, efficiency and the environment,” says Neil Wilson, president and CEO, NAV CANADA.
Moreover, the new Aireon space-based ADS-B network can be updated as required thanks to the ability to upload new software. The older Iridium satellites weren’t capable of being updated and hence have fallen into obsolescence.
But the new generation has no such restrictions and so software can upgrade them over time, developing new capabilities and enabling them to handle new protocols.
There is a large question mark amid the good news, however. How will ANSPs present space-based ADS-B to airlines, and what will be the cost? Airlines will need to ensure that the costs do not exceed the promised benefits.
Enhancements to existing technology are also under development
Adding an extra layer of complexity to the usual airline-ANSP relationship is the fact that Aireon has ANSP investors, including NATS, NAV CANADA and the Irish Aviation Authority. And NAV CANADA is destined to become the majority shareholder in due course.
Enhancements to existing technology are also under development, such as ADS-C, with the standing for Contract (see panel below).
Importantly, it is also reported that other technology providers are considering offering a space-based ADS-B service to compete with Aireon. All food for thought.
“At the end of the day, airlines rely on their ANSP partners to provide infrastructure that is safe, effective, and efficient, at a cost that enables airlines to meet rising demand for connectivity,” said Gilberto Lopez Meyer, Senior Vice President, Safety and Flight Operations.