I don't really see the reason why you're all not wanting "The Air Force" I mean, granted it is pretty redundant but even today, no one organization covers a two or three major battlefields. The Navy today has their own fleet of aircraft since they are specialized for Naval operations and the Air Force has their own aircraft that are more for general Ariel support and combat. The Army & Marines have their own helicopters that are on hand immediately to support troops.
What I'm trying to say is, I think it is very logical to assume the Air Force does exist and have super jet fighters and heavy bombers like the B-2 and what not that defend and support inter-planetary combat. The one issue I think you're all having is you're thinking about "What can I do as a player of this game" when I'm trying to explore what there is that isn't available in pixel to fly on Freelancer. With this in mind I've RP'd the Air Force (Who we can assume in Liberty has many airfields and bases on Manhattan, Denver etc) has now began to get a space-combat capability.