Nothing you wouldnt really expect in any other job interview.....
Usually an hour long panel interview consisting of the usual things such as tell us about yourself, why do you want to work here, what do you know about us, some questions on an IFR plate to check your upto speed on IFR knowledge, a few tech questions related to what you either fly or intend to ie tell us what you know about turbine engines etc. Nothing unique here.
Depending which of the two your going for it will either be a sim ride in the dash or a flight in the a/c if its Eagle. Usual stuff from what I understand (intercept a track - which way is home? - fly an approach etc)
Eagle have a group interview which doesnt differ from how other airlines do it.... ie basically seeing how you interact with your peers and demonstrate a bit of team work. Eagle also has an aptitude test. Neither of these you can really prepare for so noone is at any great disadvantage.
In short, find out a little about the company and thier a/c and be very upto speed with IFR know how.
Lets see how long this thread stays on track... how will be the first to snap
Good luck anyway catch
