Virgin Atlantic will test fly a biodiesel fueled Boeing 747 on a flight between London and Amsterdam. One of the main drawbacks of using biofuels in jet aircraft is that the fuel sets up like Jello at low temperatures. Some new blends of biodiesel with anti gelling agents have been tried in the lab but so far not at altitude in the field.
On October 5, The Biojet I, an Aero L-29 Delfin aircraft, tested biofuels when it took off from Reno and flew to an altitude of 17,000 feet (about half the height of a typical jet flight). While the first tests were done with a mixture of Biodiesel and regular jet fuel, the last flight was done entirely on 100% renewable biodiesel fuel.
Green Flight International plans on an around the world biofuel powered flight in a modified Learjet sometime next year.