By the slimmest of margins, Southwest Airlines Co. made a profit in the first quarter while other big carriers were losing money.

Southwest said Thursday it earned $11 million, or a penny per share. Revenue rose 11.6 percent.

The airline says it's seeing an uptick in business travel but is struggling with jet fuel costs, which jumped by about one-third.

Southwest said it was coping with higher fuel costs by improving productivity, and had cut the number of employees per plane by 3 percent compared with a year ago.

Last week, CEO Gary Kelly said Southwest was trying to shrink its work force through attrition and didn't plan any hiring this year. Last year, the airline convinced 1,400 employees, or about 4 percent of its workers, to take buyouts and leave the company.

Southwest said its first-quarter profit included write-downs of its fuel-hedging contracts that were designed to save money. Without those write-downs, it would have earned $24 million, or 3 cents per share, which matched the forecast of analysts surveyed by Thomson Reuters. A year ago, the Dallas company lost $91 million.

Revenue rose to $2.63 billion in the first quarter, a tick better than the analysts' forecast of $2.62 billion.

Kelly said Thursday that as the January-to-March quarter went along, Southwest saw a modest pickup in full-fare traffic — presumably business travelers.

Kelly said the company expected that second-quarter revenue would also surpass sales from the same period last year.

Southwest's profit stood in contrast to large first-quarter losses reported so far by Delta Air Lines Inc., American Airlines parent AMR Corp., and Continental Airlines Inc.

Southwest has tried to separate itself from the pack by letting passengers check two bags free, avoiding bag fees levied by most other large U.S. carriers. Southwest boosted traffic in the first quarter compared with last year, but so did some of the airlines that charge bag fees.