Great question - CRK to UBN just means Angeles City Clark Intl Airport to Ulaanbaatar Chinggis Khaan Airport. Now you’ll know what these unique codes when you look for flights! Ulaanbaatar Buyant Ukhaa Airport (ULN), Khovd Airport (HVD), Moron Airport (MXV), Dalanzadgad Airport (DLZ), Ulaangom Airport (ULO) are other airports near this flight route and their unique identifiers/IATA codes. Find deals