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Europe’s Largest Air Traffic Project Enters Digital Age as COVID-19 Complicates Operations

As the Single European Sky Air Traffic Modernization Research (SESAR) enters its 17th year, the project envisions a shift in the 2020s to a new digital services air traffic infrastructure. But can a new digitalization of European air traffic management (ATM) meet the needs of an airline industry grappling with COVID-19 while still trying to resolve the region’s decades long airspace fragmentation problem?

The SESAR project covers research and innovation managed by the SESAR Joint Undertaking (JU), as well as the synchronized Europe-wide deployment of the technology, managed by the SESAR Deployment Manager. Since 2008, SESAR JU has progressively moved the research agenda towards establishing a digital ATM architecture, where cloud computing services-based access to and distribution of critical aviation data sources and information replaces the region’s analog geographically dependent fragmented system in place today.

Virtual Centers

Within the next few years, SESAR is focused on its shift to a new digitally transformed ATM network with “Virtual Centers.”

Implementing Virtual Centers and dynamic airspace reconfiguration was first introduced as a way of improving cross-border flying in the SESAR JU's March 2019 Airspace Architecture Study (AAS). SESAR JU describes the Virtual Center as a concept that involves transforming the way ATM data services, such as flight data, radar, and weather information are ultimately shared between physical individual air traffic controllers and other stakeholders across the ATM ecosystem.

Europe's current air traffic system features decision-making based solely on the individual air navigation service providers in each European nation-state, where data is made available based on the decisions of the individual ANSPs and where needed, ANSPs are given very little control over adjacent airspace to the flight information region (FIR) that they're responsible for.

Under the vision for virtual centers, the currently fragmented structure would be decoupled and transitioned to the development of a new data servicing system where individual Air Traffic Service Units (ATSUs) work in tandem with ATM Data Service Providers (ADSPs) that provide flight data processing functions like flight correlation, trajectory prediction, conflict detection and resolution, and arrival management planning.

SESAR JU envisions a shift to a digital ATM infrastructure where data service providers use cloud computing to connect various aviation stakeholders to Air Traffic Service Units throughout Europe. Eurocontrol

Thomas Buchanan, senior adviser for international and public affairs for Skyguide - Switzerland's ANSP – explained during a Sept. 29 SESAR JU Webinar "Virtualization Center," how the concept could introduce an entirely new digital infrastructure for Europe's ATM system that uses applications and digital sources of shared data to change the way stakeholders manage the entire flight operations ecosystem across nation-state borders.

The shift to Virtual Centers will also enable Switzerland's ANSP to collaborate with its closest airspace nation-state overlords – France and Italy – using cloud computing.

"What we're transitioning toward is the creation of data centers that are location independent, we're going to be using the data center in Zurich to transfer data to both of our area control centers, west, and east. We will reuse the other data center as a cold standby to be able to come in as a contingency to the first data center should it fail. We also have external data from two sources, one of them being [French ANSP] DNSA as the prime source, and a redundant data service provision that is going to come in from [Italian ANSP] ENAV on cloud services," Buchanan said.

Skyguide's transition relies on a new cloud computing-hosted enterprise service bus providing an interface between their own internal as well as DNSA and ENAV controller working positions.

SESAR JU's Airspace Architecture Study has a three-phased plan for transitioning to the implementation of virtual centers, occurring from now until 2035 split into five-year increments. Between 2020 and 2025, ANSPs who are on board will be working on an enabling framework for the ADSPs, initially focusing on a "capacity-on-demand" service while developing standards and official certification procedures for the future ADSPs. By 2025 the group has envisioned the implementation of the new virtual centers and dynamic airspace configuration as well.

Florian Guillermet. Executive Director at SESAR Joint Undertaking, further explained the concept during the consortium's July 2020 webinar "The European ATM Master Plan in a Nutshell."

“What we’re trying to do is really to progressively disconnect or have a user connection between the physical infrastructure, the geographical layer, and the way that we provide the services," Guillermet said. "It’s the ability to provide service provisions, which are performed today in a very traditional manner with a legacy construction whereas in the past to provide ATC services you had to be close to the airspace for it to be under your control. Today, you can build a combination of that with additional components with additional service layers that can be provided from elsewhere. This brings resilience and the ability to be more flexible in the way you provide capacity and thereby to defragment the system instead of having those silos of operations that we have today.”

Are European Airlines Getting Operational Benefits Out of SESAR?

On Dec. 17, Airbus published a news release highlighting the operational efficiency benefits airlines can gain by using real-time transmission of four-dimensional trajectory data. Here, controllers are pictured at Hamburg Airport, in Germany, where these procedures are now live. Airbus

In a news update published to their website on Dec. 17, 2020, Airbus acknowledged a new SESAR-driven capability that will become available to airlines on real passenger-carrying routes in 2021: four-dimensional initial trajectory (4DT) operations, gradually entering into service across airspace controlled by France, Switzerland, Hungary, Bulgaria, Poland, and Spain. 4DT is known in the aviation industry as the concept of trajectory-based operations, where the fourth element of time is added to the three traditional latitude, longitude, and altitude dimensions used to show the updated flight path of an aircraft to air traffic controllers.

Six different airlines, including Air France, British Airways, EasyJet, Iberia, Novair, and Wizzair, participated in a two-year experimental entry-into-service program starting in 2018 to make the concept a reality. The project focused on analyzing the real-time transmission of four-dimensional trajectory data (Latitude, Longitude, Altitude, Time) as a solution to better inform ATM operations.

According to a scenario provided by Airbus, in a post-COVID-19 recovery example, summer holidays could force air traffic controllers to divert some aircraft to holding patterns and others to begin their descent before the optimum point at which the descent was planned to approach due to inaccurate visibility of the aircraft’s optimum trajectory.

“In these scenarios, the aircraft must either fly additional time or must withdraw from its optimal trajectory, which requires more fuel consumption and consequently, increases CO2 emissions. In fact, if flying in a holding pattern at 10,000 feet and 220 knots, an A320neo consumes 25 kg of fuel per minute or 100 kg for a four-minute holding. In addition, these scenarios could result in delayed arrivals, disrupt the departure flow, and increase workload for both controllers and pilots,” the company said in the release.

However, if controllers have updated information about aircraft flight path trajectories down to nearly the exact time of arrival at the next waypoint, scenarios such as these could be avoided altogether.

Another SESAR-driven efficiency advancement is the expansion of free-route airspace (FRA) to nearly all airports and air-ways in Europe. FRA is a concept of operations where airlines and other airspace users individually plan their preferred routes with preferred entry and defined exit points in certain portions of European airspace via published or unpublished waypoints without reference to the Air Traffic Service (ATS) route network. Previously, this capability had been limited to the availability of airspace or phased in with time restrictions, however, most states and ANSPs in Europe plan to significantly expand its use in 2021.

An even larger number of new concepts and technologies are under research and development, maturing to near readiness that will give airlines even more individual control over their chosen flight paths and trajectories through the core of some of Europe’s busiest sections of airspace.

European passenger air traffic (measured in revenue passenger km, RPK) is estimated to have fallen 70 percent in 2020 due to the impact of COVID-19, according to the International Air Transportation Association's latest estimate. SESAR JU

One promising initiative ready for industry adoption is the use of airborne spacing flight deck interval management (ASPA-IM)– a new technology that gives pilots more control over spacing between aircraft on arrival streams into European airports. Today, this process is mostly managed with vectoring and merging of traffic into single arrival patterns. SESAR is preparing the use of ASPA-IM for operational readiness.

"The technology addresses speed and energy control on previously assigned [Performance Based Navigation] routes. The routes can be dynamically adjusted and updated if necessary using 'what-if' capabilities," according to the European ATM Master Plan.

ASPA-IM’s key enabling link is Automatic Dependent Surveillance-Broadcast (ADS-B) and requires aircraft to be equipped with displays capable of showing ADS-B in position updates.

In SESAR 1, prototypes have been developed for Airbus A320 Real-Time Simulations (i.e. laboratory tests on cockpit simulators). In SESAR 2020, Real-Time Simulations of the ground impact were performed, according to SESAR JU.

Airlines and Single European Sky Deployment

One of the biggest users of European airspace, Ryanair, has also been one of the biggest critics of the Single European Sky. During a question and answer session hosted by Eurocontrol on Dec. 7 as part of their COVID-19 inspired "Aviation Hard talks" series, Ryanair CEO Michael O'Leary unleashed harsh criticism against the Single European Sky project for its failure to resolve the cross-border airspace sovereign authority problem.

"It’s one of the great failures of the European Union, the Single European Sky has gone nowhere in 20 years," O'Leary said. "The one challenge we’d like to call out to the European Union, which always likes to talk about the environment, is we’re still nowhere on a Single European Sky. The amount of fuel and environmental damage that is caused by air traffic control delays and inordinate flight journeys as a result of inefficient air traffic control routings continues to grow, that’s a challenge for the ANSPs."

The CEO also directly gave examples of the European cross-border flying challenges that still exist for Ryanair. "It’s a joke that we have to kind of zig-zag between national ANSPs to get from Dublin to Greece, we should be able to fly straight. We should be able to negotiate with the Belgians or with the French or with the Irish to provide us with that service without having to pay off every other ANSP," he said.

Overall, SESAR DM accounts for 343 deployment projects, valued at about €2.9 billion ($3.4 billion), of which the European Commission provides €1.3 billion in funding.

Despite O'Leary's criticism, the airline has been an active participant in several SESAR initiatives in recent years, including Data Link Services (DLS) testing and System-Wide Information Management (SWIM) initiatives as well. In September, Ryanair's feedback to new regulations associated with the deployment of technical solutions developed under SESAR was published by the European Commission, as part of the agency's effort to evaluate the ongoing performance of deployed SESAR technologies.

Enrique Ventas, who served as Ryanair's ATM project manager through November 2020 provided the airline's feedback and assessment of the deployment of SESAR, which was also highly critical.

"In (SESAR's 2015-2019 deployment phase) RP2, ANSPs did not deploy the technical and operational changes and resources planned, underinvesting, and generating unacceptable surpluses. This underinvestment led to the highest delays on record seen in 2018 and 2019," the former Ryanair ATM manager writes.

Comments publicly submitted by the Lufthansa Group were equally critical on some aspects of SESAR deployment, while also advising as to where the consortium could place some of its focus for the program to realize real operational benefits for airlines.

A topic featured in comments submitted by Lufthansa Group is one that most operators in Europe still associate SESAR's project with, the EC's 2015 decision to delay the European airspace Controller to Pilot Data Link Communications (CPDLC) mandate from February 2015 to February 2020, despite millions spent on investment in new radios, routers and software by European airlines to use cockpit text messaging in place of voice communications for some scenarios throughout the airspace system.

"While (Airline Operational Control data) AOC today is contributing massively to more efficient, safer, and ecological flight operation, CPDLC is still not at the expected performance level. One reason is the lack of bandwidth, whose CPDLC demand is quite high related to AOC," Lufthansa said in its submitted comments.

"From our perspective, other applications than the existing ones should not be introduced before the bandwidth issue has been solved and today’s ATC applications are in a stable operating mode. For the moment, the most favorable alternate/second link for AOC and ATC applications to complement VDL Mode 2 seems to be a satellite communication channel," the airline added.

In 2015, the CPDLC mandate was delayed due to the ground stations experiencing provider aborts, or the loss of data link availability, due to a lack of air-to-ground connectivity. Commission Implementing Regulation (EU) 2015/310 required legacy aircraft flying above 28,500 feet (FL 285) to be equipped with Future Aircraft Navigation System (FANS) 1/A or a router, antenna, CPDLC messaging interface and device, alerting system, and a VHF Data Link (VDL) Mode 2 radio by Feb. 5, 2020.

That date was ultimately pushed back though, and addressed by the SESAR Deployment Manager (SESAR DM) in the 2020 edition of the European ATM Master Plan.

"The main reason for the delay is the late procurement of New ATM systems capable to handle DLS functionalities and required VDL Infrastructure. The overall achievement of this objective can be expected by December 2023," as outlined in the reporting on implementation in the latest edition of the Master Plan – Level 3 Implementation Report.

While cash-strapped airlines will be wary of equipping with any new upgraded electronics to use new ATM infrastructure for datalink improvements, most are using CPDLC where and when they can. In 2019, Eurocontrol changed the way airlines classify their use of CPDLC in certain areas of European airspace, where specific manufacturers and systems are categorized by an "OPS ready list" based on ground stations experiencing higher rates of PAs with equipment identified by ANSPs.

"airBaltic operates the Airbus A220-300 aircraft. The aircraft are equipped and therefore capable to perform all modern navigation procedures such as continuous descent approach (CDA) to improve arrival efficiency and predictability, required navigation performance (RNP) transitions to localiser performance with vertical guidance (LPV) to enhance terminal operations, RNP equipment with on-board performance monitoring and alerting to continually check conformance for advanced free routing airspace, message exchanges on the airfield using controller-pilot datalink communications (CPDLC) and more to support the Single European Sky ATM Research Agency JU’s solutions." - Alise Briede, Head of Corporate Communications Air Baltic Corp.airBaltic

A representative for airBaltic told Avionics that their Airbus A220 fleet is currently using CPDLC where and when it can in European airspace.

"airBaltic uses daily and supports seamless communications for pilots and controllers switching between airspace managed by the different centers with modern CPDLC equipment on board our Airbus A220-300s, and is ready to move ahead with new initiatives to improve the ATM network," the representative said in an emailed statement.

"Currently we operate direct flights from our main hub in Riga, Latvia as well as from Vilnius, Lithuania and Tallinn, Estonia to the main European business centers,” the representative said. “We have a high level of fleet readiness to participate in SESAR initiatives with great interest and welcome the introduction of new SESAR-driven solutions such as free route aerospace, seamless ATM transitions, continuous descent approaches (CDA), (Extended Arrival Management) AMAN departures and arrivals, time-based separation, and RNP transitions to ILS or LPV approaches especially in Riga, Tallinn, and Vilnius.”