Flight operations at Kolkata airport were stalled for one-and-a-half hours on Saturday morning because of dense fog. As many as 45 flights were delayed and two of them, bound for the city, were diverted.

The operations were completely stalled between 6am and 7.30am, said an official. Even after the operations resumed, the cascading effect caused delays for some time. Several passengers missed their connecting flights from other cities because of the delay.

Met office sources said visibility had started dipping after midnight as fog set in. “The runway visual range (RVR) had dropped to below 50 metres, which led to closure of the airport till 7.30am,” said an official. Operations resumed after the RVR improved.

During the period, 23 flights that were scheduled for departure and 20 incoming flights were delayed, he said.

Two flights had to be diverted. One passenger flight from Bangalore was diverted to Ranchi while another cargo aircraft from Mumbai was diverted to Hyderabad, said officials.

Kolkata resident Shabad Punjabi was flying to Goa through Bangalore to attend a friend’s wedding.

Shabad Punjabi was to take an IndiGo flight from Kolkata at 6am for Bangalore, from where the connecting flight to Goa was at 10 am.

“I reached the airport in the morning and the boarding was at the scheduled time. However, then the cabin crew announced that the flight was delayed because of fog and it would take off as soon as the weather condition improves,” said Shabad. “We sat in the aircraft for three hours,” he said.

Finally, the flight took off around 9am and reached Bangalore around 11.30. However, the Goa-bound flight had taken off.

“There were many passengers from Kolkata who had missed their connecting flights and were crowded at the airline’s transfer desk at Bangalore airport,” said Shabad. He was accommodated on the 1.15pm flight by IndiGo.

Category III-B instrument landing system was installed at Kolkata airport early in 2018. The system allows flights to land at 50m RVR. However, the visibility on Saturday morning had dipped below 50 metres, forcing a stall on operations.

The Telegraph has reported how this winter flight operations were disrupted on several occasions, causing harassment to thousands of passengers.

Earlier on January 15, 238 flights in and out of the city were delayed and 41 cancelled because of fog at Kolkata airport and also in Delhi along with several other places in the country. Many passengers were involved in arguments with airline staff.

Saturday was warmer than usual, like the past few days have been. The minimum temperature was 19.6 degrees, four notches above normal. The reason was the high moisture incursion.

“If the moisture level dips tomorrow, the minimum may slide marginally,” said a Met official.