I filled out an application online and got invited to do an online questionnaire. I was eventually called and did a quick phone interview, and was invited to go to their corporate headquarters in Denver. The flight and hotel were paid for. The interview process was almost all day, starting at 7:30am. They will do two separate interviews per person, with two flight attendants interviewing you in the first interview and two upper level management in the second. You're alone and not in a group interview. It's casual conversation for the most part with typical questions. They ask you to read a portion of the announcement on board. I did great on my interview but was asked outright if this would be enough of a challenge for me due to my previous experience. They told me they thought it would bore me, so I wasn't chosen due to being overqualified. They ultimately don't want an impressive resume, more of a simple one. Because they gawked at my resume and were really impressed, and then said it wouldn't be challenging enough.
I also noticed that they ended picking people who were soft spoken and quiet. There was a flight attendant with another airline who was interviewing as well, and he was lively and didn't get chosen. They ultimately want people who are ordinary and unimpressive. So if you've had good jobs in the past that are of a higher pay grade and status, beware.