From what I have read in terms of Aviation Resume's, the Covering Letter is far more important than a polished resume, particularly with such large numbers coming in. With a good covering letter it doesn't really matter how big your resume is. If I'm going through my inbox I can quickly scan the covering letters without having to open the Word file attachments.
In the covering letter state something like the following:
- Who you are and where you come from and where you are now
- What you are doing now, as in what job (if any) and what you are flying
- Why you want to work with my company
- Note relevant experience from your attached resume that is relevant to this particular gig
- How quickly you can come and see me for an interview and when you can start. (Be realistic though, if you are flying in PNG don't claim to be able to move to Adelaide to start with me next week for example)