A thick blanket of dense fog enveloped the national capital and its nearby region, reducing visibility and affecting flights and vehicular movement in the streets on Monday.  As many as 20 flights were diverted and four were cancelled from Delhi’s Indira Gandhi International Airport (IGIA) due to heavy fog.

“The low visibility conditions lasted from 6 a.m. to 12:30 p.m. during which 20 flights were diverted and 4 were cancelled. Landings and take-offs continued using CAT IIIB Instrument landing system during the period,” sources said.

“After 12:30 p.m. the visibility improved to over 600 metres and the operations were shifted to CAT II.”

As per the reports, these flights had to be diverted as pilots were not trained to operate in CAT IIIB conditions.

Flights are operating at the airport under CAT III B conditions, which means the runway visual range is between 50 metres and 175 metres.

Due to the foggy weather, private airlines including IndiGo and Vistara issued travel advisory for their passengers saying flights to and from Delhi have been impacted due to bad weather and poor visibility.

In a tweet on Monday, Spicejet said, “#WeatherUpdate Due to bad weather at Delhi (DEL), all departures/arrivals and their consequential flights might get affected. Passengers are requested to keep a check on their flight status.”

#WeatherUpdate Due to bad weather at Delhi (DEL), all departures/arrivals and their consequential flights might get affected. Passengers are requested to keep a check on their flight status via https://t.co/u9dvEZRAK7.

— SpiceJet (@flyspicejet) December 29, 2019

A similar travel advisory was issued by Indigo and Vistara as well.

“#6ETravelAdvisory: Due to poor visibility in #Delhi, our flights are impacted. Do keep a track of your flight status,” said Indigo in a tweet.

#6ETravelAdvisory: Due to poor visibility in #Delhi, our flights are impacted. Do keep a track of your flight status at https://t.co/TQCzzy2a2s. For rescheduling/cancellation, please visit Plan B https://t.co/Oq5OqwbyNF. You may also chat with us at https://t.co/tBjQsmj0MT.

— IndiGo (@IndiGo6E) December 30, 2019

Vistara was forced to cancel two of its flights running between Delhi and Mumbai.

“Due to the consequential impact of poor visibility at Delhi Flight UK933 and UK996 stand cancelled for today,” the airline said in a tweet.

#ImportantUpdate pic.twitter.com/OPFtYea88W

— Vistara (@airvistara) December 30, 2019

Earlier the air carrier had informed the travelers about delay of the flights.

#TravelUpdate pic.twitter.com/URYQf7nXyf

— Vistara (@airvistara) December 30, 2019

(With input from agencies)