Kolkata | Flight operations at Kolkata's Netaji Subhas Chandra Bose International (NSCBI) Airport were disrupted on Thursday due to dense fog, affecting the movement of at least 72 flights, officials said.

Kolkata Airport director Pravat Ranjan Beuria said 39 departures and 21 arrivals were delayed due to fog in addition to 12 flights getting diverted.

"Of the 12 incoming flights, seven were diverted to Bhubaneswar, three to Ranchi, one to Chennai and one to Shamshabad," Beuria said, adding that two aircraft returned to parking bays from the ramp.

"Flight operations were affected between 5 am and 10 am. Visibility began improving after 9 am and things were normal around 10 am," an AAI spokesperson at the airport said.

Passengers faced significant inconveniences as many early morning flights were delayed. "Once morning flights are delayed due to fog, the entire schedule of airlines is disrupted, leading to a cascading effect throughout the day," an official said.

Despite being equipped with the CAT III-B instrument landing system (ILS), which allows operations in visibility as low as 50 meters, the fog reduced visibility below the permissible range.

Low Visibility Procedures (LVP) were also implemented, an official added.

"The Air Traffic Control (ATC) implements LVP when visibility drops below 800 metres, guiding aircraft to their stands using ‘Follow-Me' vehicles. LVP is also triggered when the cloud ceiling is below 200 feet," the official said.