Middle East a Key Area for Space-Based ADS-B Coverage

From the perspectives of aviation safety and airspace and airport design, the Middle East will be one of the key areas of the world where Aireon’s forthcoming space-based automatic dependent surveillance-broadcast (ADS-B) data feeds to air navigation service providers (ANSPs) will be able to offer a major contribution, according to the company.

Interviewed by AIN recently, Vincent Capezutto, Aireon’s chief technology officer and v-p of engineering, said that because the Middle East is “one of the fastest-growing areas from the perspectives of air traffic and aircraft count, you want to be proactive and predictive in terms of designing [its] airspace.”

In that context, the signing of memoranda of understanding (MOUs) with Aireon in the past few months by ANSPs Saudi Air Navigation Services (SANS) and Turkey’s The General Directorate of State Airports Authority (DHMI) to explore concepts of operations for the implementation of space-based ADS-B in their airspace is particularly encouraging, according to Capezutto.

DHMI’s airspace borders the dense Eurocontrol airspace and DHMI provided terminal and passenger service to more than 35 million domestic and international passengers using 55 airports in Turkey in the first three months of 2017. Operating in a primary airspace region for intercontinental connecting travel and overflight, DHMI regulates and controls the airspace over the high seas within the Ankara and İstanbul Flight Information Regions. DHMI intends to use ADS-B to augment its current air traffic management (ATM) surveillance capabilities and also as a contingency layer should its other ATM-surveillance systems suffer outages.

More ambitiously, SANS plans to use Aireon’s service to extend real-time air traffic surveillance throughout its entire ATM region. The Saudi Arabian ANSP particularly intends to use ADS-B to optimize its air traffic flow and reduce current separation minimums, thus providing significant benefits to airlines, according to Abdullah Alsuweilmy, chairman of SANS’ board.

Providing optimized air traffic flow management to the Middle East’s major airports as their aircraft movements continue to grow rapidly will be a key attribute of ADS-B in the region, said Capezutto. “In the past, surveillance was not contiguous. It was good where available, but [because of gaps in ATM coverage] there was noise in the system, error in what you’re looking at. But [ADS-B] gives you information that is highly predictable, tracking you uniquely and never dropping out.”

SANS’ plans to use the new ATM technology to optimize traffic flows from positional fixes outside its airspace to Saudi Arabia’s own airports—and others in nations adjacent to its airspace, such as Dubai and Abu Dhabi—to obtain the right sequencing will be particularly important as Middle East air traffic continues to grow, according to Capezutto. Importantly, the sequencing capabilities SANS expects to obtain by using ADS-B surveillance will include optimal wake vortex separation between large widebodies and narrowbodies—vital in a region which sees far more Airbus A380 and Boeing 777-300ER movements than any other region and will also see more 777X operations than anywhere else.

“In growing air traffic and keeping safety up-front, you’ve got to do something different to accommodate that growth,” said Capezutto. “Our technology will provide that contiguous surveillance” required to accommodate optimized traffic-flow management and reduce separations between aircraft as Middle Eastern traffic continues to grow. “I think [ADS-B] is one of those opportunities for those states to work collaboratively. Building that coalition of these nations will benefit from them all having the same technology.”

System Calibration

With 13 operational ADS-B payloads available to Aireon by September from the first two launches of SpaceX Falcon 9 boosters, each carrying 10 Iridium NEXT low-earth-orbit satellites bearing Aireon’s payloads (the payloads on seven satellites being drifted intentionally to different orbits weren’t yet available), “We’re at a great place in the validation of the system,” said Capezutto.

By September Aireon, together with several ANSP customers at which Aireon had already installed the server-and-terminal equipment required for them to receive its data feed, had received and validated more than 7 billion 1090MHz ADS-B positional signals received by the 13 available orbiting ADS-B payloads and re-transmitted to Aireon’s ground station on the far-north island of Svalbard.

In addition to demonstrating a validated position-update rate of five seconds (well within the eight-second update rate mandated by ICAO for ATM surveillance), having 13 operational payloads available allowed Aireon, with launch customer and shareholder Nav Canada, the FAA and private operator Polaris Aviation Solutions, to perform various test flights to calibrate Aireon’s system.

A key finding from these flights and from the huge amount of data-validation work that Aireon and its ANSP customers have performed since it first obtained operational control of its first orbiting payloads in February are that the payloads easily receive signals for ADS-B transponders broadcasting at 125 watts, the minimum power rating.

Capezutto said an even more important finding to Aireon was that each orbiting payload has an effective range of 3,700 km (1,998 nautical miles) for picking up transmissions from ADS-B—almost twice the 2,250 km (1,215 nm) coverage range that payload manufacturer Harris specified. This increases the size of each payload’s “footprint” for picking up ADS-B signals from aircraft so much that in most parts of the world it will allow three-satellite overlapping coverage of any signal.

Not only will this reduce the average positional-update time offered by the full constellation of 66 operational NEXT satellites (plus nine orbiting spares) once all are launcheed, but Capezzuto noted that having three-satellite coverage for most ADS-B messages also will allow Aireon to provide a multilateration-like, time difference of arrival method of determining any aircraft’s position. This GPS-independent, highly accurate method of determining an aircraft’s position also will make Aireon able to determine whenever and wherever GPS signals are being jammed or otherwise “spoofed,” he said.

Assisted by customers Nav Canada, Enav, Naviair, the Irish Aviation Authority (IAA) and South Africa’s Air Traffic and Navigation Services (ATNS), all of which now have Aireon’s server-and-terminal equipment installed (as does the UK’s NATS), Aireon’s ADS-B data-collection and data-validation capabilities will go up by an order of magnitude in November. During the month, after completing its initial evaluation of the performance of 10 more NEXT satellites lifted to orbit by a SpaceX Falcon 9 booster on October 9, Iridium will hand over control to Aireon of the company’s space-based ADS-B payloads on those satellites, increasing to 23 the number of operational orbiting payloads collecting and re-transmitting data.

A further five Falcon 9 launches—putting into orbit 45 more NEXT satellites to complete the constellation of operational satellites plus spares—are planned at intervals of approximately two months from October 9. Assuming Iridium and SpaceX achieve this schedule, Aireon should have full operational control of all of its orbiting payloads by September 2018, allowing it and major customers such as Nav Canada to begin trialing ADS-B for live, everyday ATM surveillance by the beginning of 2019, Capezutto estimated.

However, he said Aireon plans to make its free ALERT emergency-tracking service available earlier, in 2018—through shareholder IAA at IAA’s Ballygireen North Atlantic Communications Centre—to relevant organizations which have registered for the service. Capezutto said that the Global Beacon aircraft-tracking service that Aireon is offering commercially in partnership with FlightAware will be available by November 2018, to meet ICAO’s GADSS normal-operations flight-tracking mandate which becomes effective that month.

To date Aireon has signed 10 firm customers for its future ADS-B ATM-surveillance service, many of them ANSPS which control vast areas of oceanic airspace, such as NATS, Nav Canada, ATNS and the Civil Aviation Authority of Singapore. It also has in place an operational-validation agreement with Airways New Zealand and MOUs with more than 30 other ANSPs and functional airspace blocks covering development of concepts of operations for ADS-B coverage in their areas of airspace.