Southwest Airlines (NYSE:LUV) estimates its passenger revenue per available seat mile was up 4% to 5% in July, compared to July of 2012, according to the airline's traffic report released today.

Southwest carried 3.2% fewer passengers this past July than it did in July 2012, while flying 4.7% fewer flights. For the July-to-July comparison, revenue passenger miles dropped 0.7% on flights that increased in distance by an average 2.6%. Those longer flights increased its available seat miles by 0.6%.

The airline used only 83.5% of its flying capacity, or load factor, for the month, compared to 84.6% for last July.

Year-to-date, Southwest carried 0.9% fewer passengers than it did for the first seven months of 2012 while seeing its revenue passenger miles increase by 1.2%. The airline's load factor for the first seven months of 2013 was 80.1%, compared to 80.5% for 2012.