Air New Zealand Flight NZ8 to San Francisco will make aviation history tonight, with a demonstration of the potential for the global airline industry to cut carbon emissions by millions of tonnes a year.

Code-named Aspire 1, the Pacific crossing will be the world's first commercial service operating under a new concept known as free flight, which enables pilots to elect optimum routes and altitudes to use less fuel without air traffic control restraints.

Flight crews assisted by improved GPS-based navigation, digital technology and on-board computers will make their own operational decisions for more efficient flights rather than rely on instructions from ground-based controllers.

Air New Zealand airline operations general manager Captain David Morgan said the world-first flight would be without all practical restraints including air traffic control congestion vectoring and fixed route structures and procedures.

Captain Morgan said the US Federal Aviation Administration, Airservices Australia and Airways New Zealand would be involved.

He said the three agencies and the carrier last year created the Asia and South Pacific Initiative to Reduce Emissions - Aspire - to plan the flight with the goal of making air travel more environmentally sustainable.

The group, he said, had also worked together on introducing the Future Air Navigation System driven by the International Civil Aviation Organisation in the 1990s.

"This involved improvements to communications, navigation and surveillance which have already resulted in fuel and emission reduction benefits being delivered," Captain Morgan said.

"Air NZ has been a world leader in examining every aspect of our flight operations to cut carbon emissions by reducing fuel and from August 2004 to March this year we lowered emissions by 90,963 tonnes.

"And we are now using 36 million litres less fuel annually, delivering a saving of $43 million a year."

Captain Morgan said Air NZ had a number of other initiatives under way including improved flight planning, continuous descent profiles and more efficient use of engine power in all phases of flight.

The US National Air Transportation Association believes free flight could eventually replace air traffic controllers as aircraft are already equipped with digital instrumentation to provide high precision data.

The agency said GPS and digital technology were more reliable and safer than the human air traffic control model.

Meanwhile, Air NZ is preparing to test a new biofuel in one of its Boeing 747's Rolls Royce engines later this year. Sourced from the Southeast Africa Jatropha curcas plant, which produces seeds containing up to 40% oil, the fuel is being refined in the US before testing by Rolls in the UK.

Captain Morgan said the engine would be powered by a mix of jatropha and regular Jet A1. He said the airline expected to use at least one million barrels of environmentally sustainable fuel - around 10% of its total annual requirements - by 2013.