Hyper interesting move by Southwest today, announcing that they were seeking to buy the La Guardia take-off and landing slots — enough for seven flights a day — controlled by defunct carrier ATA.

Southwest is easily the biggest carrier that doesn’t serve CLT. It’s a low-cost airline with a market model focusing on major markets. The places it’s avoided in the past are certain expensive and delay prone big city airports and other carriers’ big hubs. Southwest has run out of easy expansion opportunities elsewhere, and is now entering exactly those markets that it avoided in the past.

So what effect does Southwest bring its special brand of luv to LGA have on Charlotte? Or more to the point, when is Southwest coming to Charlotte? Good question, and the answer isn’t obvious. NYC proper is one of the few markets bigger than CLT doesn’t currently serve (they do fly to Long Island). As such, it should increase the chance that Charlotte is the low-hanging fruit for Southwest in the future. And is seven flights a day now the buy-in for Southwest to serve a city?

The flipside of the equation is that Southwest might now be focusing most of its growth on some or all of the big Northeast corridor airports they aren’t in — Boston proper (but in Providence, RI and Manchester NH), NYC proper (they don’t currently serve La Guardia, JFK, or Newark) or Washington National (minor operation at Dulles, their 4th largest station is at BWI). If so, combined with Southwest having slowed down its aircraft deliveries, it means Southwest might get here later, not sooner.