The impact of air traffic on the environment is an international challenge which requires global solutions. However, our environmental policy and management system already apply at a local level. In that regard, skyguide is working actively with local and international bodies to reduce its ecological footprint.
The efforts begin at the terminal. Pilots at Swiss airports do not receive permission to start their engines until shortly before pushback. Also, as aircraft taxi from the gate to the runway, there are techniques either in operation, such as single-engine taxiing, or in development, such as electric taxiing systems, which allow aircraft to reach the runway without using the full power of their engines.
Efficient flight handling
New route structures, flight procedures and support tools should reduce fuel consumption and noise emissions. Four examples are iStream, XMAN, the improvement of vertical flight profiles and the implementation of direct routes (Free Route Airspace or FRA). Skyguide, together with other air navigation service providers, airlines, airports and Eurocontrol has undertaken trials concerning early morning flights into Zurich. The former ATC concept of “first come, first served” had the drawback of queuing aircraft at the arrival route entries just before the end of the night ban at Zurich Airport, causing unnecessary noise and pollution. Now, with the introduction of Target Time management, a precise slot is assigned to each aircraft. Thus, the fluidity of air traffic is increased, reducing noise as well as fuel consumption.
As Eurocontrol states, “the objective of XMAN (extended arrival management) is to optimise arrival flows by managing the speed of aircraft already in the airspace of adjacent control centres. The aircraft’s holding time at congested airports is cut by reducing their cruising speed during the final en-route phase of flights, often several hundred kilometres away from the airport. In doing so, flight efficiency is increased by reducing the overall fuel burn and CO2 emissions.” Less airborne congestion in terminal areas will also contribute to improving operational safety by reducing the workload of pilots and air traffic controllers and limiting noise. Currently, more than 75 per cent of Zurich arrival traffic is covered. With XMAN, by 2023 a reduction in CO2 emissions of 33,5 kT per year is expected.
New techniques, new procedures
The improvement of vertical flight profiles makes it possible to optimise the energy efficiency of aircraft using Swiss airspace. International letters of agreement for the Summer and Winter seasons have been signed concerning the handover of responsibilities between the controllers of different centres. This helps to optimally adjust flight profiles according to the differences between low- and high-traffic periods, governed by the principle that the energy efficiency of an aircraft depends on its cruising altitude. Thus, 7,8 GWh per year can be saved.
Finally, major savings will stem from the gradual introduction of more direct routes. Improvements are implemented every year within the framework of the Direct Routing Airspace project. This enables better planning of flights passing over Switzerland, with shorter flight routings. An even more ambitious project – Free Route Airspace – is intended to be implemented by 2022.
Skyguide has also been participating, together with Swiss International Air Lines and the Zurich airport authority, in the Atlantic Interoperability Initiative to Reduce Emissions (AIRE) programme. This is taking place under the aegis of SESAR in a joint undertaking into ATM research, to help improve the efficiency of Zurich-bound long-haul flights.
When approaching the airport, flights descended from cruising altitude to landing in several steps, moving from one altitude to the next, then “levelling out” by powering up the engines. New technology allows much more accurate surveillance of where each aircraft is located in the airspace, and therefore a more comprehensive picture of the traffic. This has led to a new technique – continuous descent operations – which allows aircraft to almost “glide” into the airport, with engines at a very low setting, thus reducing fuel consumption and noise. Once implemented at the Geneva and Zurich airports, continuous descent will result in energy savings of 133 GWh per year.