More than 11,000 passengers were stranded at the airports in the cities of Urumqi and Chengdu as thick fog blanketed west China on Sunday.
Only one flight took off from the Urumqi International Airport on schedule, while all the other flights were delayed to strand more than 3,000 passengers.
Two flights from Beijing and Shanghai to Urumqi, capital of Xinjiang Uygur Autonomous Region, had to land in Karamay and Kashgar, two cities in Xinjiang, respectively on Sunday.
The heavy fog appeared after a heavy snow on Saturday and cut visibility at the Urumqi airport to less than 20 meters.
Meanwhile, nearly 8,000 air passengers were also stranded in Chengdu, capital of southwest China's Sichuan Province.
Visibility at the Chengdu's Shuangliu International Airport was less than 20 meters due to the fog, delaying flights and requiring others to be rerouted.
China Civil Aviation Administration's regulations say that an airport's standard visibility for taking off and landing is 550 meters and 800 meters respectively.
Lu Junming, an official in charge of passenger service at the Chengdu airport, said the fog forced the airport to close for two and half hours from 7:10 to 9:40 a.m. Sunday.
A total of 97 flights were delayed while six others were cancelled, affecting thousands of passengers, Liu said.
The fog got thicker on Saturday night due to high humidity and a temperature drop, according to the city's observatory.
The visibility in the downtown area of Chengdu is less than 200 meters. The observatory predicted that the fog would hit the city again on Monday morning.
The heavy fog also caused the closure of all major highways linking Chengdu with other cities in the province.
No serious traffic jams were reported during the morning rush hour, and many people turned to public transport instead of driving their own cars for safety reasons.
(Xinhua News Agency December 9, 2007)