"At a per-passenger-mile basis, rail is about three times as efficient as travel by car, in terms of fuel efficiency, and six times as efficient as travel by air, so there are pretty substantial pollution reduction benefits both in terms of greenhouse gases and other pollutants."

VOA: standard.2010.02.15

Southwest is currently operating at 62.9% and 11.7 cents per passenger mile flown.

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Its cost per passenger mile was around one-third less than its rivals.

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Passenger yield (Passenger Revenue per Revenue Passenger Mile) for American has decreased slightly in recent years due to competition from low-cost airlines and poor domestic economic conditions.

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