CHICAGO (Reuters) -Southwest Airlines ( LUV ) surprisingly reported a third-quarter profit on Wednesday, helped by stronger revenue and lower-than-expected operating costs.

The Texas-based carrier reported an adjusted profit of 11 cents a share, compared with analysts' average expectations of a loss of 3 cents, according to data compiled by LSEG. Operating revenue totaled about $6.95 billion, compared with $6.29 billion expected by analysts.

Southwest ( LUV ) also said it expects a "meaningful" expansion of its margin in the fourth quarter.

Southwest ( LUV ) estimated revenue per available seat mile, or revenue per seat, in the fourth quarter to rise 1% to 3% from a year ago. Its non-fuel operating costs are expected to increase 1.5% to 2.5% over the same period.