Press release

U.S. domestic airlines show modest improvement in fuel efficiency since 2010

Top Performers Alaska and Spirit Airlines Widen Lead

The overall fuel efficiency of U.S. airlines on domestic operations improved by 2.3% from 2010 to 2012, less than what is needed to meet U.S. greenhouse gas (GHG) reduction goals, according to an analysis released today by the ICCT.

Alaska Airlines had the most efficient U.S. domestic operations in both 2011 and 2012, the same position it occupied in a 2010 benchmark assessment published by the ICCT last year. Spirit Airlines ranked a close second all three years. Alaska and Spirit have widened their lead over other airlines since 2010, the study found, by deploying advanced aircraft and other technologies as well as through more efficient operations practices.

Fuel Efficiency Scores and Excess Fuel Burn by Airline for 2012 U.S. Domestic Operations

Rank Carrier Fuel efficiency score Excess fuel per unit transport service  
1 Alaska Airlines 1.13 —-  
2 Spirit Airlines 1.12 +1%  
3 Southwest Airlines 1.05 +7%  
3 Hawaiian Airlines 1.05 +7%  
5 Frontier Airlines 1.03 +10%  
6 United Airlines 1.01 +12%  

JetBlue Airways

1.00 +13% (industry average)
8 Virgin America 0.98 +15%  
8 Delta Air Lines 0.98 +15%  
8 US Airways 0.98 +15%  
11 Sun Country Airlines 0.95 +19%  
12 Allegiant Air 0.89 +26%  
12 American Airlines 0.89 +26%  

Allegiant Air and American Airlines were the two least fuel-efficient carriers over the period surveyed. In 2012 both burned 26% more fuel than Alaska to provide an equivalent level of transport service—the same gap that existed between Alaska and Allegiant in 2010.

Airline ranking, 2010-2012

Airlines’ in-use fuel efficiency is directly related to aviation’s climate impact. In the U.S., aviation accounted for about 11% of energy-related carbon dioxide emissions from the transportation sector (4% of the U.S. total) in 2010. Globally, aviation GHG emissions are rising 3% to 4% annually, and are on a pace to quadruple by midcentury.

Efforts to change that trend have moved slowly thus far. A lawsuit brought by environmental groups against the Environmental Protection Agency to force EPA to regulate aircraft GHG emissions as it already does for cars and trucks remains in limbo, while the International Civil Aviation Organization (ICAO) is not expected to finalize international measures until at least 2016.

The ICCT study highlights key factors in airlines’ efficiency performance. Technology has a strong impact, unsurprisingly. “There’s a tremendous disparity in aircraft fleet age and fuel efficiency between airlines,” said Dan Rutherford, the ICCT’s program director for aviation and one of the paper’s coauthors. “Alaska is very efficient in large part because it operates a new Boeing fleet and uses turboprops on regional flights. In contrast, American and Allegiant use old, fuel intensive McDonnell Douglas aircraft and regional jets extensively.”

Airlines also use the same types of aircraft more and less efficiently. Spirit is up to 34% more efficient on a passenger-mile-per-fuel basis with its Airbus aircraft due in part to higher seating densities and passenger load factors. An A320 flight on Spirit may transport 20 to 30 more passengers than one on another carrier.

Although fuel accounts for about a third of airline operating costs, and fuel prices remained consistently high in the time period studied, the ICCT analysis found a poor correlation between efficiency and profitability. The two most efficient carriers, Alaska and Spirit, had the highest net operating profit margins from 2010 to 2012. But the third most profitable airline was Allegiant, followed by Delta Air Lines, both of which pursue a strategy of operating older, cheaper aircraft rather than investing in efficiency.

“This study should interest anyone working to reduce the environmental footprint of the aviation sector,” said Rutherford. “The persistent gap between the most- and least-efficient carriers highlights that while some airlines are investing in fuel efficiency to minimize operating costs, others profit from using the cheapest possible planes. There can be a trade-off between financial and environmental costs, with some airlines choosing the latter.”

Download the study here [.pdf]