Twelve months into an EU-funded project designed to pave the way for the roll out of fuel-saving ‘wake energy retrieval’ (WER) operations, Airbus and its partners – including Air France, Delta Air Lines, French Bee and Virgin Atlantic Airways – are continuing to refine the processes required to enable flight testing next year.
Working through a €10 million ($11.1 million) project called GEESE – part funded by the EU’s SESAR air traffic management research body – Airbus and its consortium aim to map out how to enable and scale WER operations for both transatlantic and transcontinental flights throughout Europe.
Developed through Airbus’s earlier fello’fly research project, WER sees a pair of aircraft flying in a formation – around 1.2nm (2.2km) apart – allowing the trailing jet to harness the lift generated by the preceding aircraft’s vortices.
That culminated in a flight trial carried out in November 2021 using a pair of Airbus-owned A350s on a route between Toulouse and Montreal in Canada to validate the concept, which the airframer says could generate real-world fuel savings of 5-10%.
Beginning in the second quarter of 2023, GEESE is defining the processes and systems required by all stakeholders – including flightcrew, dispatchers, and controllers - to enable WER operations at scale.
Besides the four airlines, other GEESE partners include including air navigation service providers AirBav, Bulatsa, DSNA, Eurocontrol, ENAC, ON, UAB, technology providers Indra and Frequentis, the national aerospace research institutes of Italy and Germany - CIRA and the DLR, respectively – plus rival airframer Boeing.
Key activities include running simulations involving the airlines to the validate the pairing procedures, plus further investigating the wake science – including defining the wake generated by the trailing aircraft and the safe positioning distance behind the pair.
“Today, one year into the project we are mainly working on the definition of the processes which will be needed for preparing the WER operations,” says Laura Montironi, Airbus vehicles systems architect.
These processes, developed in conjunction with the airline and controllers, will govern how the two aircraft move into formation.
“We have made good progress to agree with stakeholders on the processes, paving the way for planning and detailing all the validation activities which we’ll perform next year,” says Montironi.
With the aim of the tests to validate the formation processes rather than the uplift physics, the aircraft will be positioned at different altitudes in accordance with standard air traffic vertical separation minima, the airframer says.
But Airbus and its airline partners are still working to decide which aircraft type will be used for the testing.
“For the transatlantic flights it depends on which aircraft they will use on those sectors at the time of the trials,” says Montironi, who indicates the airframer’s preference for the A350 – a widebody twin operated by all four carriers.
Updated flightplans would only be released to crews following their acceptance by affected air traffic controllers – taking into account sector loading or airspace constraints, for example. Once uploaded into the aircraft’s flight management system, it would be available as a ‘secondary flight plan’ option.
Fuel loads would remain in accordance with the original flightplan, based on a “no-WER scenario”, adds Montironi.
“What we propose is that the respective airlines will not know if they will effectively constitute a pair. They will just declare their intention that their flight could be part of WER,” she says.
Although the testing is envisioned as type-agnostic, Montironi says the aircraft involved still need to be equipped with the functionality to automatically position the trail aircraft correctly and track the leader’s vortex.
Airbus will not “dictate how this capability or aircraft functionality should be implemented”, she says, leaving it down to the individual OEM.
The scope of tests within GEESE could also be extended to incorporate the A330 and certain Boeing types, says Montironi.
“We don’t have huge operational constraints on the aircraft itself – WER operation is mainly a flightplan change, so we are under discussion with airlines to evaluate the concept with a large set of aircraft types,” she says.
Flight testing is currently scheduled for the second half of 2025.
