Under settings one can set the pre-defined registration number for aircraft: http://www.airwaysim.com/game/Info/Settings#SettingsAircraftIt would be a huge advantage if you could not only set numbers for a specific type (like A320series) but also for a specific sub-type (like A321-100). The reason is easy: Why one would want to mix his A318 and A321? Or his DC-8-10 and DC-8-63? Or 777-200ER and 777-300?
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