It defies airline logic.

Southwest Airlines recently reported a 4Q profit of $78 million, allowing the airline to post (for those keeping score at home) their 40th consecutive annual profit. Forty years of profits…in the airline industry? Wow.

At a time when other airlines are tripping over themselves trying to see what new fee they can impose on their “valued” customers, Southwest has gone against the trend by allowing passengers to travel (gasp!) with their bags without being charged any additional fee. The airline could make hundreds of millions of additional profits, but continue to choose not to out of principle. It sounds nice, but I suspect by the time other airlines are charging us for carry on bags (less than 18 months, I promise) Southwest may be forced to revisit their policy and I suspect will finally, and certainly with great public reluctance, begin charging a nominal fee for checked luggage. Then their slogan will be carry on bags will fly for free!

How does Southwest do it? I mean, every other airline on the planet has a hard time making an annual profit four years in a row, to say nothing of four decades.

The keys to the success of Southwest Airlines are many, but some of the main ones can be attributed to their insistence on flying one type of jet only, the Boeing 737. The airline saves money on maintenance, training and airport-support equipment costs by having a common fleet. While other airlines try to integrate multiple equipment types into their fleet, Southwest uses only one - which helps to save considerable money.

The other glaring item is the shortened ground time for their planes. Obviously those silver revenue tubes only make money while they are flying, so the concept of getting a plane back into the air as quickly as possible doesn’t seem like rocket science, but for most carriers it is a hard thing to do.

The normal ground time for an aircraft is one hour or more. You will see a Delta flight arriving in Atlanta at 7:40am and the time that aircraft is scheduled to depart is 8:50am. During that 70 minute stay the aircraft is cleaned, refueled, bags and cargo are loaded and unloaded and the crews are able to complete their arrival and then pre-departure checklists.

Southwest does all of that in less than 30 minutes, on average - allowing them to get the plane back in the air in the shortest span of time possible. They are so good at “turning the aircraft” that they can actually squeeze an additional revenue-generating flight segment out of most of their airplanes…on a daily basis. Southwest has nearly 600 airplanes, meaning 600 extra departures a day, every day because of their ability to minimize the ground time of each aircraft. On a yearly basis, that’s 200,000+ more flights than the other carriers and that revenue, especially in this environment, is incredibly impressive.

The only thing Southwest doesn’t do is fly to CVG. Unfortunately as long as they are operating from the Dayton Airport, the likelihood of seeing a Southwest jet rolling down Runway 18R at CVG is slim, at best.

To say Southwest Airlines is an American airline success story is selling their profitability streak short. They are an incredible American business success story and the fact they can do it within the airline industry, with all of the ever changing fuel and labor issues, is something every other business would love to accomplish.

Well done, Southwest.