The Indira Gandhi International airport in Delhi on Monday issued a passenger advisory regarding flight operations as thick fog enveloped the national capital, bringing visibility down to zero in some parts.

The advisory urged passengers to contact their concerned airline for flight information.

“While landing and take-offs continue at Delhi airport, flights that are not CAT III compliant may get affected,” the advisory said. “Passengers requested to contact the airline concerned for updated flight information. Any inconvenience caused is deeply regretted.”

CAT III is an anti-fog landing system that is used during poor visibility.

The Meteorological Department on Monday said that the Indira Gandhi International Airport in Delhi reported zero visibility between 5.30 am to 9.30 am.

On Saturday, 11 international flights and five domestic flights to and from the Delhi airport were delayed due to poor visibility, reported the Hindustan Times.