Home Sustainable Aviation Fuel This United flight from Chicago to L.A. pilots the future of green... This United flight from Chicago to L.A. pilots the future of green air travel 4 Jun 2019 | NewsSustainable Aviation Fuel This United flight from Chicago to L.A. pilots the future of green air travel A biofuel blend cut emissions 18% from the June 5 flight–and that was just the tip of the iceberg for the sustainability measures taken on board.