Paro Airport (IATA: PBH, ICAO: VQPR) is the sole international airport in Bhutan. The airport is 6 km (3.7 mi; 3.2 nmi) from Paro in a deep valley on the bank of the river Paro Chhu. With surrounding peaks as high as 5,500 m (18,000 ft), it is considered one of the world's most challenging airports. As of October 2009, only eight pilots were certified to land at the airport. Flights at Paro are allowed under visual meteorological conditions only and are restricted to daylight hours from sunrise to sunset. It is one of four airports in Bhutan.