Dense fog and cold enveloping large swathes of the northern part of India disrupted flights and train service in the country’s capital New Delhi for a second day on Monday.

At least 463 flights leaving Delhi were delayed and 87 flights were cancelled on Monday, according to aviation website Flightradar24. More than 500 flights were delayed in Delhi on Sunday.

The aviation regulator said in an email to airlines that they are required to share accurate, real-time information about flight delays to passengers with immediate effect.

“Airlines may cancel, sufficiently in advance, such flights that are anticipated to be delayed or consequentially delayed on account of (weather) conditions beyond a period of 3 hours with a view to obviate congestion at the airport”, the Directorate General of Civil Aviation said in the email, made public on Monday.

At least 18 trains to Delhi from different parts of the country were running late because of dense fog, news agency ANI, in which Reuters has a minority stake, said on X, citing a railway document.

The city’s Indira Gandhi International Airport was not operational from 4am to 10am on Sunday (2230 GMT Saturday to 0530 GMT on Sunday) because of dense fog, the official said, leading to massive delays at airports across the country.

Social media and news channels showed angry passengers arguing with airport staff at New Delhi and other airports and one video showed a man punching a pilot announcing a delayed flight on the aircraft.

India’s federal aviation minister said the use of an additional runway was being expedited, equipped with the CAT III navigation system, which enables aircraft to land even when visibility is low.

“Incidences of unruly behaviour amidst this are unacceptable, and will be dealt with strongly in line with the existing legal provisions,” Jyotiraditya Scindia said in a post on X.

The country’s weather office has predicted dense fog and a cold wave in New Delhi for Monday and “very dense fog” on Tuesday, with a minimum temperature of 4 degrees Celsius (39.2 degrees Fahrenheit).

“Stuck in a plane at Delhi Airport since the past two hours (literally on the runway),” X user Harteerath Singh Ahluwalia wrote on the social media platform on Monday.