Airbus plans to perfect formation flying next year on transatlantic routes which could lead to a commercial passenger jet riding in another aircraft’s slipstream to help reduce fuel burn through minimising drag, writes Aimée Turner.
In a presentation seen by Air Traffic Management, the European airframer revealed that flight trials scheduled for 2020 will involve one of its own test A350-1000 aircraft flying as close as 1.5 NM behind a A350-900 operated by a customer airline. It said long haul transatlantic routes will allow it to get the most out of any test regime and will be supported by the North Atlantic air navigation service providers who manage the en route network.
The idea is not new. Formation flight is already practised during military operations mimicking migrating birds who use the technique to enable them to fly further.
During flight, the lifting force that carries a wing creates vortices which trail behind the wing. These byproducts of flight counteract the lifting force, resulting in induced drag. A single flying object, such as a bird, needs to expend more energy to overcome induced drag. However, when birds migrate together, a bird can fly on top of the vortices created by the bird ahead, thus conserving energy.
In a working paper presented at the recent ICAO 40th Assembly, experts from the International Coordinating Council of Aerospace Industries Associations (ICCAIA) talked of formation flying as a way to reduce aviation’s environmental footprint, calling it an example of the ‘unexplored field of optimisation in operation’. Automated formation flight operations in cruise, they pointed out, was also something that would require no additional equipage either on the ground or on the aircraft.
“Whilst wake turbulence is commonly considered as a threat for commercial airplanes, this concept aims at taking benefit from the energy contained in trailing vortices, without compromising safety which is paramount,” they said, adding that positioning a trailing aircraft in the area where the vortex pushes air upward could save over 10 per cent fuel.
New separation schemes would however have to be introduced to update current standards in cruise which could take up to a decade and avionics would also need to be standardised across the global fleet to automatically position and maintain an aircraft’s optimum position near the vortex – all the time while guaranteeing a protection against any wake vortex encounter and mid-air collision risks.
Interestingly, a proposal put forward at a 2009 Airbus Fly Your Idea Challenge by five PhD students studying at Stanford University’s Department of Aeronautics and Astronautics worked out how best to operate transatlantic formation flying.
The team proposed that flights leaving from the same general area make slight adjustments to their departure times, rendezvous in midair at a point close to each aircraft’s origin and fly to their destination in formations of two or three aircraft. They envisaged there would be about two to five miles separating each aircraft in the formation. One of the students imagined flights from San Francisco, Los Angeles and Las Vegas taking off, meeting around Utah and flying toward England in formation.