Dense fog continued to affect flight operations at Delhi's Indira Gandhi International Airport (IGIA) on Wednesday with nearly 100 flights being either delayed or cancelled.
For over three hours, only one runway was open because of which aircraft queued up for landing and takeoff.
The met department has predicted dense fog on Thursday as well but conditions are likely to improve after that."It is very challenging to predict fog as the maximum temperature is very low. Dense fog started from Wednesday evening and will continue till Thursday morning but the duration and intensity will gradually reduce during the next three days," a senior met department official said.
"Visibility is likely to reduce to 400 metres from 9:30 pm and is expected to dip further (below 200 metres) after 11:30 pm," he added. While 10 flights were cancelled and one was diverted, over 100 flights were delayed first due to less visibility and then due to backlog.
On Tuesday, the visibility started reducing from 10 pm but it was after 12:30 am that the fog started affecting flight movement as the runway visibility range (RVR) started dipping below 200 metres.
"Operations were suspended at runway no. 29 for three hours, from 1am to 4am, as the visibility was below 50 metres. During this time, flights were operating from runway no. 28. Though condition improved after 5 am, the fog completely disappeared only after 11 am," the airport official said.
Met department said that in the month of December, six days witnessed CAT-III category dense fog that lasted for 46 hours.
The first 22 days of December 2012 were completely fog-free. Even without shallow fog or smog, visibility remained above 1,000 metres, which is unusual.
Officials said delays are natural in fog season as the capacity of runways is reduced by 40%.