It's an absolute nightmare of fixed-field records and XML (Southwest uses Amadeus for scheduling but Sabre is just as bad; and AFAIK operations at all airlines are a chaotic hodge podge). Southwest performs all operations in Central Time because nobody's figured out how to reliably add time zones to all systems all at once. This means they have something like a 34 hour operational day, and every flight must take off and land in the same operational day.
It's a satisfying job for the right personality type!
My god. This is terrible but also riveting. I wish there was a website devoted to collecting stories of how these internal systems really work. Airlines. IRS. credit agencies. Etc.
In some recent work I've been doing for an airline, I've worked with 5 different and incompatible ways to represent a passenger, depending on what part of the system you're working in.
It's a satisfying job for the right personality type!