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If planes flew in formation like wild geese they might use five to 10 percent less fuel, European aircraft maker Airbus said Wednesday as it signed up to test the idea.

Executive vice president Jean-Brice Dorman told an online civil aviation conference that wild geese and other birds fly in a V formation to save energy, a technique known as wake energy retrieval.

"There's a kind of cushion of free lift offered by the leading bird" to those following behind, Dorman remarked.

Jet engines meanwhile produce a vortex that contains a flow of rising air that another plane could use to throttle back and reduce its consumption.

In 2016, an Airbus A350 flew three kilometres (1.9 miles) behind an A380 jumbo jet and "demonstrated more than 10 percent instantaneous fuel saving," the aircraft engineer said.

A project inspired by "biomimicry" and baptised fello'fly has been launched to see if the concept could be put into practice.

Airbus is to work with the French airline Frenchbee and SAS Scandinavian Airlines, in coordination with British, European and French air traffic controllers to demonstrate its operational feasibility, a statement said.

"In parallel Airbus will continue working on the technical solution to assist pilots in ensuring that aircraft remain safely positioned," it added.

Test flights over the ocean this year are to involve two A350 wide-body , and if it proves to be feasible the idea could become common practice by the middle of the decade, said Airbus.