Southwest Airlines Traffic Growth Continues CheapOair Staff May 9, 2011 general April Traffic Keeps Southwest on the Rise Southwest Airlines released their traffic numbers for April on Friday. In comparison to April 2010, traffic rose 8.7 percent. Its passenger revenue per available seat mile also expanded, ballooning between four and five percent. The airline also increased passenger-carry capacity by 7.5 percent; they did so by adding flights and operating longer flights on average. For the first four months period of 2011, the airline’s traffic rose 11 percent. Source: Business Week