Its a coincidence that I found this today, as lately I've been messing around with Google maps myself.
http://grandtheftauto.ign.com//maps/1/Liberty-City-Map
Looking at the map, I see only one airport ???!!! Is flying not that important anymore? Surely I must be mistaken.
Playing San Andreas, the Hydra (Harrier clone) was one of the more entertaining forms of transport and I have wasted so many hours just blowing up stuff with it.
