I had this problem as a youngling in another industry that's almost as parochial. If you can possibly dredge up a friend, relative, friend-of-a relative or relative-of-a-friend who knows the target (sorry, CP
) it can be a useful intro in a phone conversation with them. 'Bob suggested I give you a call' is a lot more memorable than being wannabe #301 for the week and may help your resume make it past the circular file.
My guess would be that ringing ahead before rocking up would good business practice, but maybe it's different for regional flying ops.
If all else fails, remember to be scrupulously polite to receptionists and well presented. It's amazing how many job seekers aren't, and it invariably gets back to whoever's doing the hiring.
Good luck!