Why is Airbus flying two A350 test aircraft to Canada, and why are they so close as to be called a formation? Well, it may be to save fuel!

Some very eagle-eyed aviation enthusiasts spotted something unusual happening over the Atlantic this morning (Tuesday the 9th). Two A350s were flying over the Atlantic, heading for Montreal (CYUL). Unusually, they are both Airbus test aircraft, with Airbus liveries, flying from Toulouse (LFBO). And even more unusually, the two A350 widebodies were flying in formation!

OK, this isn’t a tight “fingertip”-style formation, i.e. what we would enjoy at an airshow. But it is a formation, nonetheless. The two aircraft were flying within 1.5 miles of each other, at THE SAME FLIGHT LEVEL, one roughly behind the other. To be clear – this is far from normal. Airliners crossing the Atlantic, at the same flight level, would normally have 50 or more miles between them. Alternatively, they would have a vertical separation of 2,000 feet.

The Two A350 Widebodies In The Formation

The front A350 in the formation had flight number AIB01, and tail number F-WXWB. This is an A350-941 and the prototype for the A350-900 variant. The rear A350 is the bigger member of the family, i.e. an A350-1041. Appropriately, it has flight number AIB02, and its tail number is F-WMIL. Some keen aviation fans may know that the first of these jets has been sporting a “FlightLab” legend in its paint scheme. And this is a clue as to what is going on here.

As of this writing, there is no word from Airbus regarding this A350 formation (EDIT: there is now, see at the article’s end). But already in 2019, the manufacturer had published information on a very interesting project called “fello’fly”. We published an article on this, last December. What Airbus is doing, looks a bit similar to what geese do, when they fly in a V formation. And it is for the same reason the birds do it!

This A350 formation flying most probably another stage in the study of what Airbus calls Wake Energy Retrieval. All aircraft produce wingtip vortices. Simplistically put, these work like horizontal mini-tornados, emanating from each wingtip. Usually, aircraft avoid flying close to each other, to avoid interference and turbulence.

Stealing An Idea From Geese

But birds like to fly in such formations because if they do it right, they can make flying a bit easier on themselves. And this A350 formation is doing the same thing. The objective is for the rear aircraft to sit in the upward-moving air of one of the vortices of the front aircraft. Airbus believes that this could lead to fuel savings of 5% to 10%!

Of course, making this concept into a realistic tool for the airlines is a bit more difficult. A formation with two A350 testbeds is one thing. Getting commercial airliners to “meet” in the air, at the right time and place, is trickier. This will require both rule changes in air traffic control and sophisticated systems (and autopilot modes) on the planes themselves. And of course, combining different airliner types could present more challenges, as they don’t all “like” flying at the same speeds!

But Airbus is working together with different partners, to overcome these obstacles. This includes ATC authorities on both sides of the Atlantic. So what was an unusual formation test flight today, could be part of a routine flight tomorrow for you and me – in an A350 or other Airbus. Or a Boeing, too.

Source

EDIT: Airbus released this post, about the flight:

These two #A350 “fellos” performed the 1st transatlantic flight as paired aircraft from Toulouse to Montreal airport!
What's #fellofly? A follower ✈️ retrieves wake energy lost by a leader ✈️, reducing engine thrust & fuel consumption of over 5% per trip.
Watch to find out more. pic.twitter.com/xt6w2h11RB

— Airbus (@Airbus) November 9, 2021