Please check it with your regular luggage, before you get to the gate if you can!! The last flight I had on airtran out of MCO was a wreck, in large part because of those backless booster seats! I guess they aren't FAA approved, so kids can't use them at their seat.. then everyone was trying to cram them in the overheads, and they only fit one way, and take up so much room. People were getting into fights about overhead bin space, and the booster seats were a big part of the problem. It was a mess.. and the flight attendants weren't warning people about the booster seats before/during boarding.
--Heather