I'm assuming we don't need many ranks. That just becomes an HR nightmare, especially with 400+ members.
Cadet
Wingman
Flight Leader
Commander
Admiral
Alternately, we could have three sets of ranks, and members would opt which fleet they want to fly in. To the above, we could add:
~*~
Cadet
Explorer
Survey Leader
~*~
Cadet
Tradesman
Merchant
~*~
The Commanders and Admiral will have rank over all three groups, and will be the same pool of folks regardless of fleet/branch.
This is a fairly humorless hierarchy, which might ultimately be a fail.