ABU DHABI // The last of four "green" flights arrived in Sydney from Abu Dhabi at the weekend.
The Virgin Australia flight was the capstone of an experiment in increasing fuel efficiency.
Department of Transport officials said that rather than use new technology, the green flights between the Emirates and Australia calculated the most fuel-efficient routes, even as the aircraft were in the sky.
"This is achieved through close co-operation between air traffic control, the airport operator and the airline," a department official said.
Tactics included following favourable wind patterns, which was not possible before the introduction of modern communications, navigation and surveillance systems, officials said.
"Greater operating efficiencies can be achieved if the flight is able to operate on a flexible flight path that allows the aircraft to take advantage of any favourable tailwinds or, conversely, to avoid headwinds," the department official said.
"Depending on wind patterns, there are significant fuel savings to be achieved by long-haul aircraft operating over the vast oceanic airspaces such as the Arabian Sea and Indian Ocean."
Take-off and landing procedures have also been considered. An uninterrupted ascent uses less fuel than levelling off at different altitudes.
"Similarly, during the arrival phase of flight, the pilots and air- traffic controllers strive to achieve a continuous descent through to landing, and avoid using holding patterns when the aircraft is … in the air awaiting OK to land and other delaying actions that would otherwise consume fuel," the department official said.
The other three flights were from Abu Dhabi to Sydney on Etihad Airways and from Perth to Dubai and Dubai to Brisbane on Emirates Airline.
Results from the four demonstration flights will be announced this year and used as a benchmark for improvements in the air navigation system.
A spokesman for Etihad said rough estimates indicate up to 2,000kg of carbon emissions could be saved with green flights.
The green flights were an initiative by the Indian Ocean Strategic Partnership to Reduce Emissions (Inspire). The UAE, South Africa and Australia took part in Inspire under the guidance of the International Civil Aviation Organisation, through which governments and organisations are working to improve their overall fuel efficiency by 2 per cent a year until 2050.
Statistics from the Intergovernmental Panel on Climate Change show air traffic contributes to 2 per cent of global emissions of carbon dioxide, and accounts for nearly 4 per cent of the total human effect on climate.