Gimpo International Airport (IATA: GMP, ICAO: RKSS), formerly rendered in English as Kimpo International Airport, is located in the far western end of Seoul, the capital of South Korea, some 15 kilometres (9 mi) west of the central district of Seoul. Gimpo previously carried the IATA airport code SEL, which is now used by airline reservation systems and travel agencies within the Seoul metropolitan area, and was the main international airport for Seoul and South Korea before being replaced by Incheon International Airport in 2001. It now functions as Seoul's secondary airport. In 2015, over 23 million passengers used the airport, making it the third-busiest airport in Korea since being surpassed by Jeju International Airport. The airport is located south of the Han River in western Seoul. The name Gimpo comes from the nearby city of Gimpo, of which the airport used to be a part. On 29 November 2003, scheduled services between Gimpo and Haneda Airport in Tokyo resumed with services also operating at Incheon Airport.