The concept of "green flights" consists of three aspects – green departure, direct route and green approach. Separately and together, they contribute to greener flights – which benefit both airlines and passengers.
Green approaches have been developed at Stockholm Arlanda in collaboration between Swedavia, international air navigation organisations and SAS. Today they are performed by some 60 different airlines at Stockholm Arlanda. So far, it has only been possible to perform green approaches in light traffic since green and standard approaches cannot be combined in heavy traffic.
A green approach entails the aircraft descending continuously from its cruising altitude to the landing runway. With an even descent, minimal engine thrust is needed, which saves on fuel and emissions. Such approaches can save up to 150 kg of fuel and reduce noise
Since the aircraft's computer is in continuous contact with equipment on the ground, the entire flight can be adjusted to meet the exact landing time. This also means that the air traffic controller and the pilot together can plan a steady approach – the plane glides instead of descending step by step, as is the case today.
This kind of approach can save up to 150 kg of fuel and 450 kg of carbon dioxide emissions. A green approach also means that noise in the vicinity of the airport is reduced somewhat since the aircraft does not need to use engine thrust at lower altitudes.
Green departures entail a reduced environmental impact during an aircraft's departure phase by optimising ground movements and engine ground running as well as the most efficient climb-out possible en route to cruising altitude. By planning take-off while the aircraft is still at the gate, the engines can be started only when it is known that the aircraft does not need to queue en route to the runway. When the aircraft takes off, throttle is optimised all the way to cruising altitude, which also means that fuel is saved.