United Airlines has taken hypermiling to the skies.
On a flight between between Chicago and Frankfurt, the airline employed every trick in the book to show what can be done to reduce fuel burn in existing aircraft. The result was a savings of more than 1,400 gallons of jet fuel on a transatlantic round-trip flight. That may not sound like a whole lot, but with more than 600 airliners flying across the Atlantic on an average day, it adds up quickly.
The flight, made earlier this month, and was a regularly scheduled trip but United and its partners, including air-traffic controllers in the United States, Canada and Europe, had been planning it for some time. 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 ability to change altitude even by a couple of thousand feet could make a big impact depending on how close you are to the jet stream," he says.
The round trip flight was made with a Boeing 777. And like many of their road-going hypermilers, United made no modifications to the airplane. Instead the airline simply employed a host of techniques to save fuel. Unlike some hardcore hypermilers, the pilots adhered strictly to all safety regulations and did not pulse-and-glide or draft a bigger plane to Germany.
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. United also worked with the controllers at O'Hare to expedite the 777's taxiing to the runway, wasting less fuel before takeoff.
Because most of the fuel used during a flight is obviously burned during cruise, that is where United and its partners focused their efforts.
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.
Airlines already know, based upon forecasts and information from other aircraft, where to find the best winds. But pilots are forced to follow the narrow track over the ocean because vast swaths of the sea are not covered by radar. Because air traffic controllers obviously cannot see the airplanes, pilots must follow preassigned paths to avoid other aircraft.
New technology under development for the next generation of air traffic control allows airliners to see each other to maintain safe distances between aircraft. One of the key components to this new ability is the use of a system known as ADS-B.
Automatic dependent surveillance-broadcast uses GPS so an aircraft can broadcast its own position via a transmitter to other aircraft, as well as to air traffic controllers on the ground. In parts of the world where radar coverage is not available, this allows pilots and controllers to keep track of the positions of aircraft. United's Joe Burns says when the technology is used throughout the airline fleets the flexible track flying used during the demonstration flight could be used on a much wider scale.
"The next phase of this project is obviously to go back and see how do we let everybody take advantage of this all of the time" Burns says.
Photo: Drewski2112 / Flickr
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