BNK and SIN are unique codes to identify airports used in the aviation industry. They are defined by IATA (International Air Transport Association) and are commonly called IATA codes. BNK to SIN refers to a flight route from Ballina Byron Airport to Singapore Changi Airport. While you’re still figuring out your travel plans, it’s not a bad idea to learn the names and codes of other airports around these areas: Singapore Seletar Airport (XSP).