I've been trying to learn about this process also. From the de-brief's I've heard....
Certainly spend time practicing your answers to questions about "Tell me about a time you helped a customer," "Tell me about a time your leadership failed," "Tell us about yourself." The interview portion is over in a flash (30-45 minutes after a review of your paperwork). With three people on the panel that is only one of two questions from each. You want to ensure you can briefly (2 minute answer) hit your high points and try to score maximum points. While preparing go back through your transcrips all the way back to High School. I forgot that I had been President of a couple clubs, Dean's list in College, etc. All of these examples of success help the candidate look good.
As I understand it (and I'm no expert) Delta uses a very objective process to maintain consistent results on different days with different applicants. This is why some days everyone gets the conditional letter and on other days only a couple get the letter.
My understanding is the Delta interview is like a Type Ride. If they called you, they want you to pass. However, there are several areas where you can make mistakes and deny yourself the opportunity - and - like a Type Ride failure in one section can't be made up by doing well on other portions. You have to meet standards in
every section. Even after the interview, you can make errors in the Psychological evaluation, or get hung up on medical issues (FAA Class 1 with a harder hearing and vision test). The whole process is very thorough. But, they are not looking for Chuck Yeager. Like most airlines they are looking for solid, safe, pilots who show up for work on time, nice people and people who can pass training. In fact General Yeager has probably crashed a few too many airplanes to be hired by Delta.
Good luck - everyone really is pulling for you and there to see you make it.
It is neat to see what is going on down there on Virginia Avenue.