KIX stands for Osaka Kansai Intl Airport, while CCU stands for Kolkata Netaji S. Chandra Airport. These codes are often called IATA codes, a set of identifiers established by IATA (International Air Transport Association) that is widely used by airlines and the aviation industry. Fukuoka Airport (FUK), Tokyo Narita Airport (NRT), Sapporo Chitose Airport (CTS), Tokyo Haneda Airport (HND), Okinawa Naha Airport (OKA) are other airports near this flight route and their unique identifiers/IATA codes.