The world's first commercial aircraft powered partly by biofuel has taken to the skies.
The Virgin Atlantic 747 took off on route from London Heathrow to Amsterdam using a 20% biofuel mix of coconut and babassu oil in one of its four main fuel tanks.
Virgin boss Sir Richard Branson said the "historic" flight was the first step towards using biofuels on commercial flights.
But he said fully commercial biofuel flights were likely to use feedstocks such as algae rather than the mix used on the passenger-less test run.
The flight was made in partnership with Boeing, engine maker General Electric, and Imperium Renewables, with the aim of reducing carbon emissions.
Environmental groups immediately dismissed the test flight as a "publicity stunt". Campaigners said carbon savings from biofuels, often made from organic materials such as wheat, sugarcane and palm oil, are negligible.
And there is rising concern biofuel crops could be competing with food production, damaging the environment and displacing indigenous local populations.
Sir Richard said his fuel was "completely environmentally and socially sustainable" and does not compete with food and fresh water resources.
He said: "Today marks a biofuel breakthrough for the whole airline industry. Virgin Atlantic, and its partners, are proving that you can find an alternative to traditional jet fuel and fly a plane on new technology, such as sustainable biofuel.
"This pioneering flight will enable those of us who are serious about reducing our carbon emissions to go on developing the fuels of the future, fuels which will power our aircraft in the years ahead through sustainable next-generation oils, such as algae."
