So how much of an impact will Southwest Airlines have when they start flights from Charlotte? Great question.

First, understand that in the eastern U.S., Southwest is not a point-to-point airline. Instead, its flights are almost all to a series of small to medium-sized hubs. These hubs don’t have banks like US Airways’ operations here in Charlotte, where a whole lot of planes arrive in a short period of time, passengers change planes, and all those planes then leave again within a tight time period. Southwest’s flights at its big stations are spread out much more evenly through the day. Still, if you have 70+ flights a day from one city, that creates connecting opportunities. And, yes Southwest will gladly do a connection for you.

Now let’s look at Southwest and AirTran (which Southwest bought) existing service to other cities in the Carolinas, which would be to Charleston (CHS), Greenville-Spartanburg (GSP), and Raleigh-Durham (RDU)) for this summer:

Destination CHS GSP RDU
Atlanta (ATL) 4
Baltimore (BWI) 3 2 7
Chicago Midway (MDW) 2 2 4
Denver (DEN) 2
Ft. Lauderdale (FLL) 1
Houston (HOU) 1 1 1
Las Vegas (LAS) 1
Nashville (BNA) 1 1 4
Orlando (MCO) 1 4
Philadelphia (PHL) 3
Phoenix (PHX) 1
St. Louis (STL) 1
Tampa (TPA) 3
Total 7 7 36

All service is on Southwest except for ATL-RDU, which is on AirTran. Some of the RDU flights are seasonal: Baltimore, Chicago Midway, Houston, and Orlando each go down a flight in October. Yes, that means Houston service is seasonal for Raleigh-Durham.

Charlotte’s service on AirTran this summer is 4 x Atlanta, 3 x Baltimore, and 1 x Orlando. The good news is that’s more flights than AirTran has had out of CLT in a couple of years. The bad news is that come mid-August, it falls back to 3 x Atlanta and 3 x Baltimore. That’s right, AirTran is dropping CLT-MCO come mid-August — it’s not even offering Saturday only service from late August through the end of October. And the November schedule, which is expected to contain major changes, itn’t out yet.

As previously noted, ATL-CLT looks to be in trouble. If Atlanta and Florida are toast, that starts to limit Southwest’s potential impact here — flights to those markets make up a third of Southwest/AirTran flights from RDU this summer.

As for the other routes, Baltimore and Chicago Midway are givens. Say 4 or 5 x BWI and 3 x MDW. A flight to Denver would also seem right. Phoenix and/or Las Vegas are also possible, especially at some point down the road, but Denver is higher yielding and closer.

Southwest failed in its attempt to establish a hublet in Philadelphia. The PHL-RDU route is a holdover from that. So don’t expect CLT-PHL on Southwest. St. Louis isn’t happening either.

The wildcards are Houston and Nashville. Nashville is about 90 percent of the market size (by dollar value) of Atlanta but only one airline current serves the route (US Airways, of course). So that seems possible. Houston once a day? Maybe, Southwest does that sort of stuff.

So overall between 8 and 13 flights a day. A bit more serve that what AirTran currently provides but not a radical increase in service. Or put another way, we’re likely to only have a little more service than Charleston, SC gets.