A UK budget airline which shares its name with a distinctive New Zealand songbird has been named the world's greenest airline.
TUI Airways, which operates out of the United Kingdom and Ireland, was found to be the world's most eco-friendly carrier by the Atmosfair Airline Index rankings.
Air New Zealand came a respectable thirteenth on the comparison of 125 international airlines, while the regional brand Air New Zealand Link was marginally less green at spot 19.
The rankings compiled by AAI compared greenhouse gas emissions of the top 190 airlines in the world and evaluated the carbon output per passenger carried.
The aircraft model, engine type down to the shape of the wingtips and occupancy of flights were all take into account when ranking the airlines' green credentials.
TUI sealed the top spot with its fleet of highly efficient aircraft such as the Boeing 737-800 and a roster full, highly packed economy seating.
A cramped cattle-class perch might not be as luxurious as the Emirates' first class air suite – one of the largest space allocations in the skies – but at least you can fly with a clear conscience. Unsurprisingly, the UAE carrier Emirates came way down the AAI green rankings at position 108.
Meanwhile other UK airlines, including the national carrier British Airways, were also amongst some of the worst.
In the battle for the moral high-ground in Australian aviation Virgin Australia at 18th pips the national carrier Qantas in 49th. Though, perhaps the enforcement of the airlines' new carry on restrictions will reduce fuel consumption in next year's rankings.
Dietrich Brockhagen, managing director of Atmosfair, explained his company's AAI rankings show that more needs to be done.
"Our results show that the efficiency improvements of the vast majority of airlines worldwide is not sufficient.
"We need new, synthetic and CO2-neutral fuels and other more radical measures to curb CO2 emissions in the sector," he said, in a statement accompanying the results.
The report praises airlines running the latest generation of aircraft such as the Boeing 787-9, Airbus A350-900 or the A320neo in their fleets which are also achieving the most efficient results on their carbon output per passenger.
The statement insisted that "new aircraft models considerably raise the bar in terms of carbon efficiency."