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What Is America’s Most Fuel-Efficient Airline?

Commercial flying is a greenhouse gas emission-intensive mode of travel regardless how fuel efficient airlines claim to be, but some carriers are significantly more efficient than others. The International Council on Clean Transportation (ICCT) ranked 15 major U.S. airlines in order of fuel efficiency, but the group said more work needs to be done to learn why some airlines are more efficient than others.

More than 9 million commercial flights depart U.S. airports each year at a time when aviation accounts for the fastest-growing greenhouse gas emissions in the U.S. transportation sector. The aviation industry contributes about 2 percent of global carbon dioxide emissions, and the European Commission projects that by 2020 the global aviation emissions will be about 70 percent higher than they were in 2005 even with airlines' efforts to improve fuel efficiency. 

The International Council on Clean Transportation's ranking of U.S. airlines operating in 2010 based on its model of fuel efficiency.
Credit: ICCT

The ICCT used U.S. Department of Transportation airline data to determine that the least fuel efficient airline, Allegiant Air, is 26 percent less fuel efficient than the most efficient airline, Alaska Airlines, which flies its Boeing 737 jets to numerous remote Arctic locations — think Adak Island, Nome and Prudhoe Bay. Conversely, Allegiant, flies mainly decades-old McDonnell Douglas MD-80-series aircraft known for guzzling fuel.

ICCT’s analysis ranked the 15 mainline air carriers that were operating in the U.S. in 2010, including Continental Airlines, which merged with United Airlines the same year.

Spirit Airlines and Hawaiian Airlines tied for the second most-fuel efficient, followed by Continental Airlines and Southwest Airlines. Joining Allegiant among the least fuel efficient carriers are American Airlines, AirTran Airways, US Airways and Delta Air Lines.

The Department of Transportation data only go so far, however, and ICCT analysts say there are many unknowns about how fuel efficient airlines are overall. The group’s analysis was based on an economic model using only publicly reported data to compare airlines’ fuel efficiency relative to each other, said analysis co-author Daniel Rutherford, ICCT aviation and marine program director.

“In essence, anything that an airline does to reduce its fuel burn is properly credited in the top-level rankings providing they’re reporting their data properly,” he said. “The challenge then comes to explaining those results.”

The analysis suggested numerous factors that could affect fuel consumption: an aircraft’s age, engine design, size, seating density and use of fuel efficiency equipment such as “winglets” on the tips of a plane’s wings, and an airline’s operational procedures.

The study accounts for an airline’s total departures and the number of miles an airline flew each revenue-generating passenger (called revenue passenger miles, or RPMs). The more RPMs an airline provides per unit of fuel, the more efficient the airline.

“However, travelers’ ability to avail themselves of an airline’s RPMs is also important, with each airline striking a unique balance between getting passengers to their final destination as directly as possible with the need to provide access to all its potential customers,” the study said. “Carrying more, flying further and offering more flights — either by serving more airports or flying more frequently — all increase fuel burn.”

ICCT assigned each airline a fuel efficiency score, with 1 being the industry average and any score greater than that signifying an airline that is more fuel-efficient than average. The analysis showed a 26 percent gap between the least and most fuel efficient airlines.

The group called the analysis a “first step” in providing an accurate picture of the U.S. commercial aviation industry’s fuel efficiency, and plans to update the report annually as more information about airlines’ fuel efficiency becomes available.

“Unfortunately, few consistent standards exist to compel airlines to disclose publicly comprehensive data on fuel use and aircraft operation, particularly outside of the United States,” the analysis concluded. “While companies typically view such figures as proprietary, more complete and accurate data would help policymakers make sounder decisions about this highly complex industry.”

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