Southwest doesn't fly first class. The closest it comes to that is a "business select" service that gets you on the plane first, and maybe gives you a free drink. These are some reasons it's taking much longer to integrate AirTran, acquired in 2011, into the Southwest system than expected. The airline took a $26 million charge for AirTran costs in the second quarter, more than double the charge of a year ago. That's despite the fact that AirTran flies 737s, the same plane Southwest uses, although it also flew the smaller Boeing 717s, and was the largest operator of those planes. AirTran also used four hubs, while Southwest used none, and full integration is taking a year longer than expected. I flew Delta from Atlanta to LaGuardia often during the 1990s, and the contrast is enormous. Atlanta has a huge terminal that now has seven concourses and its own subway system, along with five runways running in parallel, one of which was placed on top of a freeway. LaGuardia, by contrast, has multiple terminals and runways that cross to catch variable prevailing winds. Some runways extend into Flushing Bay. I saw a rainstorm close the whole place down for hours last year. Winds can change at a moment's notice, in any direction, even down. It's amazing the place functions. In this week's Southwest accident, a 737 from Nashville came down nose-first and crushed its own landing gear, finally skidding to a stop. There were 16 injuries, mostly minor, and no deaths. It also closed LaGuardia for hours that evening. The bottom line is that airplanes are to our time what buses and passenger trains were to the first half of the 20th century. They're relatively safe, prosaic, and not romantic at all. Southwest has recognized this, and become quite large in the process, but I wouldn't put money to work in their stock, or any airline stock, because the margins are too thin and fuel costs too variable. The risk, romance and pleasure are mostly gone from air travel, and so are the profits. At the time of publication, the author had no investments in companies mentioned in this article. Follow @DanaBlankenhornThis article is commentary by an independent contributor, separate from TheStreet's regular news coverage.