Airbus fello’fly: reducing fuel consumption up to 10%


Airbus’s revolutionary fello’fly concept, aims at reducing emissions and fuel consumption, with estimated efficiency gains of up to 10%. Inspired by the flight of migratory birds - which fly together to save energy - two aircraft are set to meet and fly in formation.

The follower aircraft will retrieve the energy lost by the wake of a leader aircraft, by flying in the smooth updraft of air it creates and thereby significantly reducing emissions on long-haul flights. If the fello’fly demonstrator project were to be put into operational use and all wide-body aircraft equipped with wake energy retrieval technology, it is estimated that fello’fly could eliminate over 3.5 million tons of industry CO2 emissions annually. Considering that the long-haul aviation segment is the most difficult to decarbonise, this would be a significant achievement.

Nick Macdonald

“The theory about wake energy retrieval has been around for a long time. However it is only fairly recently that flight testing by numerous aerospace organisations proved the size of the benefits. In 2016, at Airbus we performed our first flight tests and found over 10% instantaneous fuel and emissions reductions.”

Airbus completed 2020 with a number of exciting achievements, including some key advances on the on-board technology side and a lot of progress in drafting a first concept of operations for oceanic airspace. These activities will continue in 2021, with further flight testing to allow a level of maturity to perform a demonstration in Atlantic airspace together with the collaborating airlines and air navigation service providers.

“However, fello’fly remains a technology demonstrator” emphasizes Nick Macdonald. “Plans for the future, in particular regarding making the technology commercially available, depend entirely on the outcomes of these demonstrations.”

Fello’fly is a demonstrator project set to boost the environmental performance of aircraft and help the industry towards its target to reduce CO2 emissions by 50% by 2050.

The reduction in engine thrust for follower aircraft results in reduced fuel consumption. Instantaneous fuel burn reductions of over 10% in certain cruise configurations have been shown possible. Trip fuel savings for a typical wide-body mission are expected to be around 5% and upwards.

But how complex will it be to put fello’fly into place technically, operationally and commercially?

“The big strategic issue here is all about the speed at which our industry can innovate, by which I mean move technology into real airline operations” says Nick. “There are two aspects to this challenge, which are first that the regulatory framework is available to support the use of technology, and second that the operational players are able to use it.

"At this stage, we are looking primarily at the transatlantic flow, as a starting point. At a later stage, it will be necessary to study implementation in other regions in order to prepare global deployment. Then on the regulatory side, there is a challenge to have the regulations in place to allow the new regulatory minima for two aircraft flying 3km apart, and with a new division of responsibility for maintaining their separation. Assuming we demonstrate the viability, we anticipate the technology could be available around 2025. We would need regulations to be updated in advance to support this timeline, and the environmental contribution that fello’fly can make.”

Airbus fello'fly infographic

The EUROCONTROL Network Manager is proud to be part of fello’fly, working alongside Airbus, airlines and air navigation service providers to assess its operational viability.

Together with colleagues from Airbus, airlines and air navigation service providers (ANSPs), EUROCONTROL is playing a key role in the team, bringing extensive operational experience to the project assessing how such a new kind of operation can be integrated into today’s network infrastructure.

“Increasing the sustainability of air traffic is a key priority for us in the EUROCONTROL Network Manager to support the sector in reducing aviation emissions by 50% by 2050. We are working with all partners in the aviation ecosystem on innovative solutions for the future and I’m excited to support and be fully part of the fello’fly project.”

As the vast majority of fuel and emissions reductions would be achieved on flights made by wide-body aircraft, the focus of the project is on traffic flows between global regions. The fello’fly CONOPS addresses transatlantic traffic, but could be easily transposed to other oceanic airspaces. The full potential of emissions savings will depend on the degree of commercial adoption, and could deliver even greater environmental gains with further extension of the concept, e.g. to flight formations involving more than two aircraft.

The fello’fly CONOPS unites EUROCONTROL, two airlines (SAS, Frenchbee) and two ANSPs (DSNA, NATS). The CONOPS aims at inserting fello’fly flights into existing traffic while preserving the fuel efficiency enabled by the fello’fly concept, without compromising on safety. The operational conditions of fello’fly are unique and require a creative ATM approach:

  • There are already many 'natural' pairs of flights which can be observed. These are created by airlines having similar departure schedules and the concentration of traffic into track systems;
  • EUROCONTROL plays a significant role by providing crucial traffic flow information to help identify the most probable pairs in real-time, and by facilitating on-time departures of aircraft planning to take advantage of wake energy retrieval.

Significant effort is still required before operations could start in 2025

2021 will be a busy year for the fello’fly team, with a number of flight tests taking place to develop and test the on-board systems technology. The intention is that if the systems development is successful, a demonstration of the CONOPS will take place in transatlantic airspace in the last quarter of the year with the involvement of EUROCONTROL and other industry collaborators. Additionally, the regulatory and commercial frameworks necessary to support the technology and its operations are also being assessed.

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