This has obviously been in the works for awhile. I keep thinking back to some of the comments from the DO last week about Midwest adding codeshares with other airlines.

With this announcement, I'm assuming Frontier will move its flights to the D Concourse in MKE.

How long before Frontier pulls the plug on its partnership with AirTran?

When will AirTran drop its 1x daily MKE-DEN flight (which was converted to year round service)?

In any event, this is good news (but not surprising) ^