Great question - MEL to VIE just means Melbourne Airport to Vienna Intl Airport. Now you’ll know what these unique codes when you look for flights! This flight route has multiple associated airports, so we think it might be helpful to learn the name and codes of them as well. They are Salzburg W.A. Mozart Airport (SZG), Innsbruck Kranebitten Airport (INN), Graz Thalerhof Airport (GRZ), Klagenfurt Airport (KLU), Linz Hoersching Airport (LNZ).