After conducting a ‘perfect flight’ trial between London and Edinburgh in 2010, where each stage of the journey was designed to achieve the highest efficiency possible, UK air traffic management provider NATS launched an even more ambitious trial.

This project, named ‘Topflight’, aimed to develop, demonstrate and integrate some of the aspects of the Single European Sky research initiative (SESAR) in a real world scenario and measure the results to see where gains were made.

In conjunction with partners, the first phase of this NATS led trial took place in 2013 and focussed on 100 British Airways flights across the North Atlantic between London and Toronto or Montreal. These flights aimed to achieve ‘gate-to-gate’ optimisation through using elements of SESAR, such as providing an initial Oceanic profile before departure, continuous climb and descent, direct routing, the flexible use of military airspace and reduced engine taxiing.

The full list of optimisation opportunities was developed and, of the hundred flights, a quarter were able to achieve all efficiency measures and 70% achieved at least half. These test flights not only resulted in an estimated half a tonne of CO2 saved per flight, but also provided analysts with valuable information on which aspects of the trial produced the greatest savings. These results were then fed back to the team at SESAR to further inform their work.

The second and on-going phase, which began in early 2014, is called XMAN and is focussed on reducing the amount of time aircraft spend in holding stacks on arrival at Heathrow. To achieve better efficiency when significant delays are expected, NATS is working with neighbouring air traffic management organisations to slow down aircraft en-route, meaning they spend less time holding on arrival, burn less fuel and emit less CO2.