Last year, you might remember reading that NATS has been working with the French, Irish and Canadian air navigation service providers (ANSPs), DSNA, IAA and NavCanada to support an Airbus demonstration of airliner formation flight.
Well, that came to fruition in early November when we successfully enabled the first transatlantic flight from Toulouse to Montreal of two A350 test aircraft, paving the way towards formation flying becoming a future reality.
What is the project?
Known as 'fello'fly', the project aims to demonstrate the potential for two aircraft to fly close together during long-haul flights to allow the follower to conserve fuel.
It was inspired by studies of the formations that geese make in flight, where they take it in turns to lead to help each other conserve energy.
The project developed a concept of operations that described how aircraft could be paired up. Once aircraft were in the same vicinity, with the follower 1000ft below the lead, responsibility for aircraft separation would be transferred from air traffic control to the aircrew.
The project uses the wake vortices (circular patterns of upwards air) that aircraft create as they fly. This pattern of air means that if an aircraft is flying close enough behind the leader during cruise, it will benefit from free lift. Fuel savings are increased if the lighter aircraft rides the vortex of the heavier aircraft. To maximise fuel saving, ideally aircraft should fly at the same altitude with the follower about 1.5 nm behind the leader. Airbus uses new technology to maintain this formation automatically.
Paul Spooner, Shanwick Supervisor
This video explains how the fello'fly concept works in more detail:
So how was it put into practice?
Planning the project
One of the first stages of planning was to create our demonstration procedures. A flight like this has never been carried out in live traffic, so there were no procedures or rules to follow.
To give you an idea of how unique this trial was, the minimum separation for aircraft in oceanic airspace is 14 nm (approx. 26 km); however, the aircraft in this trial spent much of the flight flying 1.5 nm apart. This means the aircraft were flying significantly closer together than they would even in a radar environment.
With aircraft flying so close together, it was essential to ensure the safety of the test aircraft and other airspace users. For the purpose of the trial, the airspace surrounding the aircraft was reserved, meaning there was a flight level above and below the test aircraft available if they needed to separate, as well as airspace available to allow the aircraft to move laterally should weather conditions change.
The trial involved working with our fellow ANSPs to ensure communication was efficient when handing over two aircraft as opposed to one.
We worked DSNA, IAA, NavCanada and the CAA to change the phraseology that air traffic controllers use to speak to aircraft. For example, aircraft are usually told that they are 'cleared' to fly to a specific flight level whilst climbing. 'Approved ' was agreed as an alternative during the test flight, reflecting the fact that we were permitting the pilots to carry out a manoeuvre for which they had separation responsibility.
This new technology is ideally suited for use on the Ocean where there are enough aircraft flying very similar routes for long enough to really gain valuable fuel savings and emission reductions. We will continue working with Airbus and other ANSPs, aiming for widescale deployment in a few years. There are also plans to engage Boeing to increase the pool of aircraft capable of participating.
Adrian Clark, Advanced Tools and Concepts Development Manager
What's next?
The fello'fly trial outbound flight successfully took place on Tuesday 9th November, returning the following day and the results have been encouraging.
The two aircraft spent roughly 80% of the flight in formation, enabling the follower to achieve a fuel saving of over 5% (or around 2 tonnes).
We're now planning to continue to work with Airbus with a goal of achieving routine widescale formation flights in oceanic airspace by the middle of the decade.