THE INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION
This report assesses and compares the fuel efficiency of airlines serving the U.S. domestic market in 2010. The analysis presented here rigorously compares the efficiency of all airlines independent of size, network structure, or type of service, with a methodology that improves upon previous efforts in four fundamental ways. First, it uses airline-reported fuel consumption data, rather than modeled estimates, to account fully for all the ways in which airlines can reduce fuel burn (e.g., aircraft technology or operational practices). Second, it develops an efficiency metric that recognizes that airlines burn fuel to provide both mobility (measured in terms of passenger miles traveled) and access (frequency of service and number of airports served), allowing an equitable comparison between airlines. Third, the efficiency metric distinguishes productive from nonproductive miles flown by identifying those airlines that operate particularly circuitous routes. Finally, the study attributes the transport service provided by and fuel consumption of affiliate carriers to mainline carriers in order to enable comprehensive comparisons across carriers’ full business operations.
Figure ES-1 summarizes the principal findings of this study, comparing the relative fuel efficiency for the domestic operations of the 15 largest U.S. airlines in 2010 across each carrier’s entire network. A fuel efficiency score of 1.00 corresponds to average in-use fuel efficiency for the U.S. market in the given year, with values above or below 1.00 representing airlines that fare better or worse, respectively, than the industry average. Since fuel use is inversely proportional to fuel efficiency, the fuel efficiency score can be directly linked to the amount of fuel consumed, and consequently the emissions generated, by each airline to provide a comparable level of service.
Of the carriers with above average fuel efficiency in domestic operations, Alaska Airlines (ranked first), Spirit Airlines (tied for second), and Hawaiian Airlines (tied for second) are relatively small carriers serving geographically limited markets. Continental Airlines, in fourth place, was the most fuel-efficient full-service legacy carrier (established prior to deregulation) while Southwest Airlines (fifth) was the most efficient carrier operating on a point-to-point rather than a hub-and-spoke business model. United Airlines (eighth), with a fuel efficiency score of 1.00, was equal to the average for 2010 U.S. domestic operations. Many, although not all, of the carriers with worse fuel efficiency than the industry average were, or subsequently have been, the subject of merger activity, including Delta Air Lines (11th), US Airways (12th), AirTran Airways (13th), and American Airlines (14th). The least efficient airline in this ranking, Allegiant Air, also happened to have the most profitable U.S. domestic operations during the 2009 to 2011 period.
Figure ES-1 highlights a large gap between the most and least efficient airlines serving the U.S. domestic market. The figure suggests that Allegiant would have used 26 percent more fuel than Alaska Airlines to provide a comparable level of transport service in 2010. Approximately one-third of this variation can be attributed to differences in technology alone, with the balance of the variation related to a complex set of characteristics such as seating density, operational practices (e.g., fuel loading/ tankering, single-engine taxi, etc.), load factor (the number of passenger miles traveled as a percentage of seat miles available), and route circuity (the total number of passenger miles traveled divided by the number of intended, or “productive,” passenger miles).
An additional analysis was performed to estimate the fuel efficiency of U.S. airlines across the ten most traveled domestic city pairs. Owing to a lack of primary airline data, this analysis relied on an aircraft performance model to estimate fuel burn. Overall, route-based fuel efficiency, as measured by passenger miles transported per pound of fuel, differed among airlines serving the same route from 9 percent to as much as 90 percent because of aircraft technology, load factor, seating density, and route circuity. Shorter trips, for example, north-south travel along the coasts, are significantly more fuel intensive on a passenger mile basis than transcontinental flights. This general finding is attributable in part to the large amount of fuel consumed during takeoff and to the use of smaller, less efficient aircraft such as regional jets on shorter routes. In many cases, because of variations in aircraft choice, seating density, route circuity, and such, an airline offering efficient flights between a major city pair may not rank well at the network level. These results highlight the need for better route- and even flight-specific data for consumers wishing to select less carbon-intensive flights for a specific trip.
Several conclusions can be drawn from this work:
- Within the mature, competitive U.S. aviation market, there remains a large gap in fuel efficiency among airlines flying on domestic routes even at today’s high fuel prices. Fuel prices alone may not be a sufficient driver of in-service efficiency across all airlines.
- Although technology utilization is important, operational practices vary significantly from airline to airline, impacting in-service fuel efficiency. To address the energy and environmental effects of aviation, policies that facilitate and encourage efficient operations as well as technologies should be considered.
- The most efficient airline for a given itinerary varies by city pair, with the top performer on one route not necessarily being efficient on another. Thus, route-specific data are required for consumers to make more environmentally responsible decisions.
- Accurate, transparent data are the cornerstone for assessing the efficiency of airlines. Data in this report can help inform consumers about the relative efficiency of their air travel. Reporting requirements for more detailed data on aircraft fuel consumption would go further in supporting any future policies to improve efficiency.
About the International Council on Clean Transportation
“The International Council on Clean Transportation is an independent nonprofit organization founded to provide first-rate, unbiased research and technical and scientific analysis to environmental regulators. Our mission is to improve the environmental performance and energy efficiency of road, marine, and air transportation, in order to benefit public health and mitigate climate change.”