On launching the sim there is no problem and all is well, except I am unable to change livery. The following error is displayed in the terminal.
directory(): listing '/mnt/FlightGear/Aircraft/737-300/Models/Liveries/' denied (unauthorized directory - authorization no longer follows symlinks; to authorize reading additional directories, add them to --fg-aircraft)
Also, and more frustrating, is that when I am in multiplayer mode all aircraft different to the one I have loaded are seen as the "nerf glider." If I store all the aircraft in the default aircraft directory the aircraft are now visible correctly. I am still unable to change livery.
Also the sim does not load with multiplayer enabled, but this is a minor inconvenience.
I do not want to hold my aircraft in the default directory as this is using up SSD space.