DALLAS — Southwest Airlines Co. said Thursday its traffic fell slightly last month, but a key measure of revenue jumped, showing that carriers have had some success in raising fees and ticket prices.
The airline, which carries more passengers domestically than any other U.S. airline, said it flew paying passengers 6.48 billion miles in April, a 0.6 percent decrease from 6.52 billion miles in April of 2009.
But passenger revenue per available seat mile, which measures how much money Southwest made to fly each paying passenger one mile, increased an estimated 18 percent to 19 percent compared with a year earlier. Besides raising fares, airlines can increase how much money they make per passenger by raising or expanding fees.
The Department of Transportation this month said U.S. airline revenue from so-called ancillary fees rose 42 percent to $7.8 billion in 2009. The biggest chunk of that came from checked baggage fees.
Besides checked bags, other fees include those for reservation changes, pet travel and mileage sales.
Southwest doesn’t charge for the first two checked bags, but it still ranked fourth in fee earnings. Southwest charges $50 for a third checked bag, as well as fees for pets traveling in the cabin and unaccompanied minors.
Southwest’s capacity, or number of available seats, rose 2.9 percent to 8.22 billion available seat miles. Since Southwest flies only one kind of plane, the airline cuts capacity by taking aircraft out of service.
The carrier’s load factor, or occupancy rate, rose 1.8 percentage points to 78.8 percent.
For the first four months of the year, traffic was up 1 percent. Capacity was down 5.5 percent and Southwest’s occupancy rate fell 5 percent compared with January though April of 2009.