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U.S. domestic airline fuel efficiency ranking, 2013

The newest release of this annual rankings report compares the fuel efficiency, and therefore carbon intensity, of U.S. airlines on domestic operations in 2013. The report also investigates changes in fuel efficiency since 2010, both for individual airlines and the industry as a whole.

Domestic flights in the U.S. account for about 24% of global CO2 emissions from commercial aircraft, and are expected to grow an average of 1% per year over the next 20 years, increasing annual emissions from 116 million metric tons (MMT) in 2014 to about 143 MMT CO2 by 2034.


  • Alaska, Spirit, and Frontier tied as the most fuel-efficient domestic carriers in 2013. Alaska and Spirit have consistently led the performance ranking since ICCT’s original baseline analysis of 2010 data. Frontier leapfrogged Southwest Airlines thanks to a large (+10%) one-year improvement.
  • The fuel efficiency gap between the most and least efficient airlines widened slightly to 27% in 2013. Allegiant improved its fuel efficiency in 2013 by adding second-hand Boeing 757-200, A320 and A319 aircraft to its older MD-80s fleet starting in 2011, while American’s fuel efficiency declined by about 1.5% from 2012 to 2013.
  • Overall, there was no net gain in the fuel efficiency of U.S. domestic operations from 2012 to 2013. The slowing industry improvement rate in recent years is linked to a lack of new, more-efficient aircraft types, the time lag between new aircraft delivery and penetration into the in-use fleet, and diminishing gains from increasing load factors.
  • There continues to be no clear correlation between airline profitability and efficiency, though all 13 major U.S. domestic carriers were profitable in 2013.