ATA (American Trans Air) is an Indianapolis based airline that got its start as a charter/vacation operator. They moved into scheduled service in the early 90's, and have found themselves quite a niche in the midwest.

They offer a charter-type an all coach based "cattle" operation. Nothing bad (except a crowded coach experience), their prices are usually very reasonable.

My wife's parents belong to Ambassadair, which is their vacation/travel club.

Nothing to worry about, they're a good airline.

http://www.ata.com/