I’ve done hiring at both the Regional and Major level. There are obviously many factors and panel members each have their own priorities. I’ll give you mine and those expressed by people I know.
First and foremost, appearance and attitude are huge. As this is an interview we have to assume this is the best you’re going to look and behave. If you can’t manage to iron your shirt or shave for the interview, there’s no way you’re going to on the last day of a 4 day trip. If you’re cocky, arrogant and obnoxious at your interview, you’re going to be a monster after a few years.
Next ALL airlines want to know you want to work for them. You need to convey that and after some experience we can usually tell who’s sincere and who isn’t. Personally I’ve never been a fan of the “shotgun” approach in applying. Most of have that dream job and I firmly believe (at least in the beginning) putting all your eggs in one basket. You will be asked “where else have you applied?”. If you answer everywhere it will not be well received. If you say only here and you haven’t, you’re lying and a good experienced panel member can smell it. But if it’s true it will come across. If you don’t get the nod then sure start applying elsewhere but why not be optimistic and focused initially when it counts? Study the airline. Impress them with your knowledge of their history, fleet, recent announcements, etc. All will play well in your favor. I also don’t agree about the extra-curricular stuff. I for one never cared if someone was a boyscout or collected stamps. It comes back to the age old question “will it be cool to be locked in the cockpit with this pilot for 4 days?”.
Finally (and my personal favorite), read, pay attention and LISTEN. When I interviewed at my Regional they sent out an email stating they wanted the following forms and copies in the following order. Paperclipped and not stapled. When we all showed up the first thing they did was collect everyone’s paperwork while we watched an intro video. After the video they called out a bunch of names. Those called proudly stood up, until they were told “sorry, you’re done”. Anyone who’s papers were not paperclipped or not in the correct order were immediately sent home. If you can’t get this right why should they trust your with their jet. At my Major they passed around a hat and each person pulled out a question. We were instructed “read your question aloud and answer it, you have 1 minute”. I actually felt bad when the first person read their question and then pontificated about what the question meant and the importance of the question until they called time and the question was never answered. I didn’t feel bad for the next person who did the same thing. Or the next. When they got to me guess what I did? I ANSWERED the question. Wanna guess who got the job and who didn’t?