A heavy blanket of fog, possibly one of the thickest of the winter season, engulfed the national Capital, leading to the disruption of flights in and out of the national and international terminals on Monday. The fog also badly affected train operations, delaying many trains due to the poor weather conditions, causing inconvenience to hundreds of passengers.

Air traffic was suspended at the Indira Gandhi International Airport for around three hours, leading to delay and diversion of around 150 domestic and international flights. Between 8 p.m. on Sunday and 8 a.m. on Monday, around 150 flights, either arriving here or departing from here were cancelled or diverted due to extremely poor visibility at the airport, according to airport officials.

Around 51 domestic and international flights departing from here and 39 scheduled to arrive here during the time period were cancelled. Fifty-two incoming flights were diverted to Amritsar, Lucknow and other destinations. A Delhi-bound SpiceJet flight from Goa, with 132 passengers and four crew members onboard, had to make an emergency landing at 9.50 p.m. as it was running short on fuel.

Many passengers claimed no prior information was given about the delay or cancellation of their flights.

Eye-witnesses said long queues were seen at airline counters for refunds for cancelled flights or to get a seat on any early flight. Around 15 flights coming to Delhi were diverted to Amritsar.

Delhi has been witnessing thick fog since Sunday morning. Dense fog started to descend at the airport around 7 p.m. on Sunday evening. Within two hours, the runway visibility dropped from 500 metres to less than 100 metres. Operations almost came to a grinding halt around 10 p.m. after runway visibility dipped to less than 75 metres, the minimum required visibility condition for an aircraft to land using the CAT IIIB instrument landing system.

The minimum required visibility for an aircraft for the Low Visibility Take off is 125 metres and 150 metres, depending upon the size of the aircraft. The Delhi airport is equipped with two CAT-III B compliant runways, which enables a CAT-III B trained pilot to land a CAT-III B compliant plane when runway visibility is merely 75 metres. Flight operations started around 4 a.m. after visibility improved.

Similarly, the thick fog adversely affected train operations on Monday with 37 trains, mostly Delhi-bound, running late by several hours. Among the trains affected were Rajdhani, Duronto and Shatabdi. Rajdhani trains coming from Guwahati, Ranchi, Patna, Howrah, Mumbai and Bhubaneswar are running late by three to five hours. Services of the Sealdah Duronto and Kanpur Shatabdi were also been affected. While Jansadharan Express is running 10 hours late, Vikramshila Express and Samprakranti Express are behind schedule by eight and seven hours respectively, according to the Northern Railway data.