An airplane in flight. Photo: Wikimedia / xlibber

[Via Satellite/Aviation Today 12-10-2014] The European Space Agency (ESA) and Europe’s Single European Sky ATM Research Joint Undertaking (SESAR JU) program are teaming up and taking steps to boost efficiency in worldwide aircraft tracking, capacity and management through satellite-based communications. ESA’s Iris  program looks to create a satellite solution for advanced aviation communications and has aligned itself with SESAR initiatives to improve future Air Traffic Management (ATM) technologies and techniques.

The Potential of Iris

The Iris program has been in the works for several years, aiming to apply the satellite-based system with the current Very High Frequency (VHF) ground-based communications that may become overloaded in the future, according to Oscar del Rio, Iris and Aeronautical Resources Satellite-based (ANTARES) project manager at ESA. The satellite communications system aspires to open up channels to data links and ATM operations not widely available today, and unlock aircraft tracking in four dimensions (latitude, longitude, altitude and time), known as 4-D trajectory management, by 2018.

“Iris will enable 4-D trajectory management via satellite, for both continental and oceanic airspaces, as a safe and reliable service. Communications will take place via robust data links and will ultimately be used by the vast majority of aircraft, complemented with conventional voice communications between pilots and controllers,” said del Rio.

There are high-hopes for the improved data link communications Iris may provide, particularly in the realm of increasing airspace efficiency — something highly sought after by operators, airlines and Air Traffic Controllers (ATCs) alike as market forecasts predict air traffic will increase at nearly 5 percent annually for the next two decades.

Iris in the Short Term

A Nov. 26 public-private partnership established between ESA and satellite operator Inmarsat, worth more than $18 million, has kicked off Iris Precursor: the first phase of the program. This first stage is based on Inmarsat’s SwiftBroadband Safety program and will enable enhanced 4-D trajectory management through improved data link technology.

“Trajectory-based operations will bring improved predictability and flow (separation, conflict resolution, optimized approaches, better planning, etc.), enhance safety, and provide additional capacity. Furthermore, there will be direct savings in fuel and emissions since more efficient routes into busy airports will be provided, thus cutting down holding time spent in the air and on the ground,” said Aarti Holla-Maini, secretary general of the European Satellite Operators Association (ESOA), who noted that satellite communications will be key in enabling those operations. “It is recognized that terrestrial means alone will not offer the capacity required for those new services.”

According to del Rio, the enhanced forms of data link technology enabling 4-D trajectory include Controller Pilot Data link Communications (CPDLC) and Automatic Dependent Surveillance-Contract (ADS-C), a system complementary to Automatic Dependent Surveillance-Broadcast (ADS-B), which both the European Aviation Safety Administration (EASA) and the FAA have mandated compliance.

“ADS-C supports periodic reporting of aircraft position and location,” del Rio explained. “In addition, ADS-C is designed to report a number of other parameters that can be used as needed. Actual positions and intent information are automatically transmitted at intervals set by an ATC, or can be triggered by request by the air traffic management, or by an event (e.g. change in vertical rate, lateral deviation or altitude).”

As aircraft equip for the Future Aircraft Navigation System (FANS 1A) mandate, ADS-C equipage is following suit, del Rio added. He expects the pick-up to continue as low-cost satellite terminals are made available for all types of aircraft through programs like Iris. But the program will take time, careful planning and a unified disposition on spectrum allocations for Iris — which some argue are unnecessary and potentially damaging.

Del Rio noted that ADS-C, CPDLC and other 4-D trajectory management services are not facing spectrum regulatory issues. Today’s satellite-enabled flight tracking systems use L-band Mobile Satellite Service (MSS) allocations — 1.5/1.6 GHz — for these applications. But he added that the Iris Precursor program validates the aviation industry’s need for dedicated spectrum.

Spectrum Dispute

After the disappearance of the Malaysian Airlines Flight MH370 aircraft, the International Telecommunications Union (ITU) accelerated efforts to establish global aircraft tracking. At the 2014 ITU Plenipotentiary Conference (PP-14) this summer, the United Nations agency passed a resolution to consider allocating spectrum specifically for aircraft tracking at the World Radiocommunication Conference in 2015 (WRC-15). The decision received mixed responses, with Inmarsat supporting the resolution, while ESOA suggested the ITU not to rush into major decisions.

“The Iris Precursor program confirms the need for using spectrum with priority access for aviation in the continental airspace. New generation satcom clearly offers the potential to augment existing ground-based VHF aviation communication services. The dynamic frequency utilization of the Iris system will ensure that aviation spectrum is efficiently used for ATC data link operations,” Del Rio said.

According to Holla-Maini, ESOA was concerned that the administrations attending PP-14 would not have the full background information available on this issue. She warned that placing spectrum allocations on the agenda for WRC-15 could lead to a flawed decision, as the technical studies typically conducted in advance will not be complete.

Some proposals at PP-14 suggested using the direct satellite reception of ADS-B signals to track aircraft over water. Holla-Maini pointed out that this and other solutions such as L-band Aeronautical Mobile-Satellite (Route) Services (AMS(R)S) are already available and do not necessitate action at WRC-15. Though content with the decision the ITU reached, she emphasized that MSS operators have alternative solutions ready today.

“With the tragic loss of Malaysian Airlines flight MH370, there is an emotional backdrop to this issue, which is quite understandable, but this cannot be the basis for hasty, unnecessary decisions. ESOA is pleased with the decisions of the PP-14 on this issue and European operators plan to work with the ITU and [the International Civil Aviation Organization] ICAO to help meet future requirements for flight tracking,” Holla-Maini said.

Iris in the Long-Term

ESA and Inmarsat are detailing a long-term plan for Iris that will follow the Precursor program. Through Iris Precursor upgrades to Inmarsat’s SwiftBroadband system to meet European standards for ground-based VHF data links, with pre-operational flight trials planed for 2016, the two organizations will provide the necessary technology for short-to-medium term ATM air-to-ground communications with 4-D flight path control, to be expanded on in the later stage.

“Iris Long-Term, the second stage, will result in the full implementation of the Iris system, meeting the ultimate communication needs of future ATM services,” said del Rio. “Iris Long-Term will be based on the evolution of Iris Precursor to guarantee continuity in the technical service provision. Iris Long-Term will offer global interoperability based on a global communications standard.”

The Iris Long-Term standards are currently being drafted in ESA’s two-year ANTARES phase B study. One of ANTARES’ main objectives is to create a new communication standard for satellite-based ATM communications up to the level required for international standardization. Others include validating the new standard by Single European Sky requirements, designing a comprehensive satellite communications system, and developing an airborne low-cost user terminal prototype. The benefits of this system would very likely extend beyond Europe, according to del Rio.

“While the initial focus will be on Europe, the capabilities developed will open opportunities for deployment in North America and other regions where the growth of air traffic is placing strain on ground-based VHF networks,” he said.

The communication standard acceptance review is currently planned for March 2015.