The Flighgear Aircraft and Scenery should be packaged for ubuntu. As there is over 1gig of aircraft (100's of packages) and 13gig of scenery it might not be suitable to host them in the main ubuntu repos (space and clutter), they could be hosted in a launchpad project package archive (Could be added when you install the fgfs-base package). However the default aircraft should be hosted in the main ubuntu repos and these are required to run the game (Flightgear can download scenery on demand).
The aircraft and scenery should be packaged separately with proper screenshots and information for especially the aircraft as this already exists.
This would allow the fgfs-base package to recommend the default aircraft but allow users to just install the base package if they desire to. This would also link flightgear to the ubuntu upgrade system allowing fixes and patches to be released properly for aircraft and scenery and the aircraft and scenery to update during a release upgrade.
This can then be implemented in the software centre and any flightgear related gui.
(I have begun testing packages to install aircraft and have uploaded some to my ppa over at https://edge.launchpad.net/~cbaines/+archive/fgfs-aircraft