Airbus and partners complete successful 'fello’fly' rendezvous trials

Question and Answers: 

Q: Why are these trials being conducted? A: The 2025 trial phase focused on validating the high-precision rendezvous process, a prerequisite for paired flight operations. It aimed to demonstrate that two aircraft can be guided safely and predictably to the same point in space and time while complying with air traffic regulations and maintaining complete vertical separation.

Q: What fuel savings could fello’fly eventually deliver? A: Airbus reports that once fully operational, wake energy retrieval has the potential to reduce fuel consumption by up to 5 percent on long-haul flights.

Q: What navigation and positioning systems supported these trials? A: Trials used high-accuracy satellite navigation systems such as GPS and Galileo to maintain precise relative flight paths between aircraft. Enhancements such as satellite-based and ground-based augmentation, as well as real-time kinematic corrections, were evaluated to improve positioning accuracy and integrity. Inertial navigation units were integrated with GNSS and datalink data to ensure continuous relative-position awareness even if satellite signals varied.

TOULOUSE, France - Airbus in Toulouse, France, working with Air France in Paris, Delta Air Lines in Atlanta; French bee in Paris; Virgin Atlantic in London; and air traffic operations partners AirNav Ireland in Dublin, Ireland; DSNA in Paris; EUROCONTROL in Brussels, Belgium; and NATS in London, has completed a new phase of trials for the company’s fello’fly fuel-saving project.

Fello’fly applies a technique inspired by migrating geese by pairing flights so the trailing aircraft can capture lift generated by the leader. The lead aircraft’s wake creates an upward flow of air that reduces the propulsion work required by the follower, a process known as wake energy retrieval. Airbus says the technique has the potential to reduce fuel burn by up to 5 percent on long-haul flights.

The latest trials involved eight flights over the North Atlantic Ocean between September and October 2025 as part of the SESAR Joint Undertaking’s GEESE project. The goal was to show that the rendezvous process, which requires two aircraft to meet at a precise point at an accurate time while keeping complete vertical separation, is feasible and safe under real operational constraints. Wake energy retrieval itself has not yet been tested in commercial service, but demonstrating safe and repeatable rendezvous is a required milestone before efficiency testing can continue.

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Navigating 

A key element of the trials was validating the navigation and positioning performance needed for paired operations. The concept uses high-accuracy satellite navigation from GPS, Galileo, and other constellations to maintain precise lateral and vertical offsets. Operators are also evaluating augmentation systems, including satellite-based augmentation, ground-based augmentation, and real-time kinematic corrections, to improve accuracy and integrity. Inertial navigation units are fused with GNSS data and datalink updates to maintain a stable relative-position solution even in degraded satellite-signal conditions.

Surveillance and situational awareness also played a central role. The trials relied on ADS-B Out and ADS-B In to provide continuous position and intent information between aircraft, as well as ADS-C services in oceanic sectors for long-range tracking. These cooperative surveillance inputs allow both aircraft and air traffic controllers to maintain complete visibility of the paired geometry throughout the rendezvous and paired-flight sequence. The program is evaluating how these inputs support safety monitoring and trajectory management as fello’fly moves toward operational maturity.