For one, the A380 is not operated by any NA carriers at the moment. Obviously the Soviet aircraft (Tupolev, Sukoi, Illyushin, and Antonov) are and most likely never will bear an "N-number" registration. Boeing 737-200s are also not operated by any US carrier (I believe AS got rid of them).
Last edited by fromYYZ_flyer; Jan 2, 2013 at 1:21 pm