Don Mueang International Airport (Thai: ท่าอากาศยานดอนเมือง , or colloquially as Thai: สนามบินดอนเมือง ) (IATA: DMK, ICAO: VTBD) is one of two international airports serving Greater Bangkok, the other one being Suvarnabhumi Airport (BKK). The airport is considered to be one of the world's oldest international airports and Asia's oldest operating airport. It was officially opened as a Royal Thai Air Force base on 27 March 1914, although it had been in use earlier. Commercial flights began in 1924, making it one of the world's oldest commercial airports. The first commercial flight was an arrival by KLM Royal Dutch Airlines. Don Mueang previously carried the BKK IATA code (subsequently transferred to Suvarnabhumi) and was an important hub of Asia and the hub of Thai Airways International. Since the opening of the new airport in september 2006, it has become a regional commuter flight hub and the de facto low-cost airline hub. In 2015, it became the world's largest low cost carrier airport with the main hub for Nok Air, Thai AirAsia, Thai Lion Air, and New Gen Airways.