Southwest Airlines Co. (NYSE: LUV) saw its February traffic jump 3.9 percent from a year earlier, marking the company's first traffic increase in three months.

Southwest, the largest U.S. airline carrier, also said Wednesday its capacity increased 6.2 percent. The rises extends a trend that had continued throughout most of last year, after Southwest acquired rival AirTran in May.

The Dallas-based Southwest's load factor -- the percentage of seats filled -- fell to 75.2 percent, down from 76.9 percent last February. Southwest also said the passenger revenue per available seat miles, a key profit metric in the industry, increased 4 percent compared to February 2011.

Southwest reported strong fourth-quarter earnings that exceeded analyst expectations.

Southwest rival JetBlue Airways Corp. has not yet reported February traffic, but it also beat analyst expectations in the fourth quarter by nearly tripling earnings. JetBlue's January traffic jumped 13 percent, and its capacity grew 12 percent from the previous-year period. Passenger revenue per available seat mile rose 10 percent.

JetBlue said it expected February's preliminary passenger revenue per available seat mile to jump somewhere between 7 percent and 8 percent.

Shares of Southwest were down 0.81 percent to $8.53 in midday trading.