Airport visibility started deteriorating around 3 am, forcing the authorities to implement low visibility procedures (LVP) around 3.30 am, when the runway visual range (RVR) was 1,700 m on Runway 28 and 500 m on Runway 29.

“The visibility dropped to zero around 6.30 am due to a very dense spell of fog over IGI. The fresh spell is a result of Western Disturbances and an upper air cyclonic circulation over central Pakistan and adjoining west Rajasthan,” a senior official of the IGI Met department said.

“The RVR on Runway 29 was falling very fast and flight operations had to be suspended on the runway. Only Runway 28 could be used for arrivals and departures till 7.15 am. Later, Runway 28 was used for departures and Runway 29 for arrivals,” an airport official said.

The LVP lasted for over 5 hours and was terminated at 9 am. At least 70 flights, including 43 domestic and 27 international operated during the LVP. “During this time, at least 48 flights operated using the Category I instrument landing system (ILS), six operated using Category II, 13 used Category IIIA, while three others operated using the Category IIIB ILS,” an airport official said.

An Air India international flight, AI 840, had to be diverted to Jaipur while five others were cancelled. Over 50 flights were delayed, with the delay time ranging between 30 minutes and 4 hours.

“Apart from others, CD 7618, coming from Ahmedabad, was delayed for 3 hours; 9W 610 from Leh was delayed for 2.5 hours and 9W 3320, from Lucknow, was delayed by an hour. In departures, IT 203 to Bangalore was delayed for 3 hours and IT 3334 to Guwahati was delayed by 3 hours,” the official said.