Thai Airways International and Thai air traffic control provider Aeronautical Radio of Thailand (Aerothai) have conducted the first round-trip ASPIRE flight.
The Bangkok-Auckland flight, operated with a Boeing 777-200ER, took off on 5 May, says Thai. It operated the return flight on 8 May.
Aerothai recently joined ASPIRE, which stands for the Asia and South Pacific Initiative to Reduce Emissions. ASPIRE was established by the US FAA, Airservices Australia and Airways New Zealand.
Japan's Civil Aviation Bureau and the Civil Aviation Authority of Singapore have also since joined the initiative, which aims to reduce aviation's impact on the environment.
Airlines from the countries who joined the initiative have been carrying out demonstration flights to analyse ways to reduce fuel use and carbon emissions.