It’s a bird! It’s a plane! It’s two planes…mimicking birds?

This is the vision that Airbus, the world’s largest aircraft manufacturer, is trying to bring to life with its airline partners as part of broader industry efforts to make commercial aviation more sustainable. Delta announced at CES 2025 that it would take part in a test run later this year of Airbus’s “fello’fly” technique, which is inspired by migrating geese, to improve fuel efficiency and reduce emissions.

The solution is still years away from being used on commercial flights, but there’s optimism about the long-term potential of fello’fly to help the aviation industry achieve its decarbonization goals.

“There is no other relevant solution to decarbonize wide-body flying across the transatlantic,” Amelia DeLuca, Delta’s chief sustainability officer, told Tech Brew. “You cannot put batteries in those airplanes.”

Taking flight

The idea behind fello’fly is to pair two aircraft together on long-haul flights, in a formation inspired by the V-shaped flight pattern geese use when they’re migrating. The technique has been shown to reduce fuel consumption and emissions by at least 5%.

“With this flying technique, the first aircraft creates an uplift that drives fuel efficiency for the following aircraft, called wake energy retrieval, which can reduce fuel consumption,” according to a news release.

Jonathan Beck, Airbus’s project leader of fello’fly, told us that the manufacturer has been working on this initiative for many years. Airbus conducted flight tests to assess the technology’s performance benefits, and later demonstrated its real-world capabilities. Now, with the upcoming test run with airlines and other entities including air traffic controllers, the company aims to get on the same page with other industry players on how to integrate fello’fly into commercial operations.

“The goal is to demonstrate that we can put two aircraft together at the same waypoint at a given time, following the concept of operation that we are developing,” Beck said.

Instead of determining ahead of time what flights will be paired together, that decision would be made once the planes are already in the air, to account for the reality that many flights don’t leave exactly on time, he explained.

Co-pilots

Delta announced its involvement in the fello’fly test run during its keynote presentation at CES. The airline is Airbus’s largest operator, and the companies are working together on numerous aviation tech solutions, including around fuel efficiency, wing performance, and advanced aircraft assistance. And both companies are working toward an industry goal of achieving net-zero carbon emissions by 2050.

DeLuca pointed to fello’fly as a prime example of the formal relationship between Delta and Airbus’ innovation labs. The science, she noted, has already been proven; now, it’s about figuring out how to incorporate the technique into the complex orchestrations Delta and other airlines go through on a daily basis to get thousands of flights off the ground on time in all kinds of conditions.

“We understand and are really intrigued by the potential fuel savings,” DeLuca said. “But the challenge around, how do we coordinate all the different logistics, the technology, the pre-planning, as well as the live planning that needs to happen with commercial aircraft…It will be quite an effort to even get the live trial to happen, and that will really be focusing on identifying what it looks like in practice to get those two planes to sync up over the Atlantic…and then to be able to stay the appropriate distance as they simulate how it would look to fly.”

Though 5% fuel savings might seem small, DeLuca characterized it as “massive” for transatlantic flights. Such innovations can also help airlines bridge the gap while other decarbonization solutions develop.

Planes powered by batteries and hydrogen are still many years from being viable solutions for long-haul flights, DeLuca explained. And although the industry is investing heavily in sustainable aviation fuel as a means to reaching net-zero emissions by 2050, it’s still expensive and not yet being produced at scale.

In the meantime, Delta is focused on myriad ways to make its flights more fuel efficient, and ultimately, according to DeLuca, it’ll take a combination of solutions to make commercial air travel sustainable.

Beck noted that getting fello’fly off the ground also will require buy-in from global regulators; Airbus is in the process of engaging with them.

What excites him about the technique is that “it’s nature-inspired. It’s very easy to understand. And it’s quite cheap in terms of development to make it happen, because it’s using what’s there already.”