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How Many MPG Does a Boeing 777 Get?Hypermiling has gained a lot of popularity these past few years. It was even the Oxford Dictionary Word of the Year for 2008 ("'Hypermiling' or 'to hypermile' is to attempt to maximize gas mileage by making fuel-conserving adjustments to one's car and one's driving techniques."). But while the word is mostly use to talk about driving cars more efficiently, there's no reason why the same concepts can't apply to other vehicles. Case in point, United has hypermiled a Boeing 777 plane across the Atlantic to test fuel-saving techniques. How did it turn out?
Several fuel-saving techniques were used, but the main goal was demonstrating how a flexible flight path allows pilots to take advantage of favorable winds, says Joe Burns, director of flight tests at United. [...]
The fuel savings started before leaving the gate. Instead of using the onboard auxiliary power unit to power the plane and provide air conditioning on the ground, United used external power. That still requires energy, of course, but plugging into the grid is more efficient. [...]During a transatlantic flight, an airliner typically is assigned a fairly limited track of airspace to follow to its destination. It's like flying through a narrow pipeline. On United's demonstration flight, pilots were assigned a flexible track -- in essence, a bigger pipeline. The wider swath allowed the pilots to wander a bit, going where the best winds will help push the plane along. Or, in the case of a headwind, minimize the resistance. (source)
How Much Fuel Was Saved?The results of all this one the Chicago to Frankfurt and back flight was over 1,400 gallons of fuel saved. A rough estimate puts this at around 6-7%, which is pretty good considering that the plane was completely unmodified. Multiply that by the number of planes in the air and you get a pretty big amount of fuel saved and pollution avoided.
What will be needed before these kinds of flexible flight paths become common is next generation air control to make sure that planes can maintain a safe distance from each other. This is especially true over oceans where radar coverage is extremely limited.
The Future of AviationThis kind of adaptive flight route, combined with newer engines and more modern plane designs (flying wings, advanced materials, etc) will almost certainly mean that flying will be much more fuel efficient in the future. Combine this with 2nd or 3rd generation biofuels produced in a responsible way, and flying's impact will be much smaller than it is now.