Three international flights were diverted on Sunday morning after failing to land at Tribhuvan International Airport due to poor visibility, affecting around 600 passengers and straining space inside the terminal.

A widebody aircraft of Turkish Airlines en route from Istanbul was diverted to New Delhi. An Air China flight from Chengdu returned to Lhasa, while a Sichuan Airlines narrowbody aircraft also turned back to Chengdu.

Passengers had completed check-in and were entering the departure hall when the disruptions occurred, leading to a sharp build-up of the crowd, an airline staff said.

Devendra Prasad Shrestha, assistant spokesperson and chief air traffic controller at the airport, said poor visibility along the approach path forced the diversion of three international flights and also affected a few domestic flights. “Weather conditions began deteriorating after 7am, with visibility dropping to around 1,600 metres,” he said.

Two systems are used for landings in poor weather at Kathmandu: VOR/DME and satellite-based RNP-AR. Shrestha said a minimum visibility of 1,600 metres is required for VOR/DME approaches and 1,100 metres for RNP-AR.

Visibility improved to around 2,500 metres after 11:30am, with conditions gradually becoming favourable, the airport said.

The airport handles around 90 international and over 250 domestic flights daily, with about 25,000 passengers passing through its terminals each day.