This year, Delhi witnessed its foggiest December in 15 years. The Indira Gandhi International Airport (IGI) was fogged out for a total of 76 hours — 13 nights and mornings.
According to the Met department, this December witnessed the third highest dense CAT III fog hours ever since analysis of data started in 1981. CAT III dense fog is experienced when visibility falls below 200 metres.
The record for the longest duration of fog in December (since 1981) so far is 179 hours, experienced in 1998. The second highest duration stands at 85 hours in 1997.
“The special feature of the fog this year was that it occurred in one spell and persisted from December 15 till the end of the year. It only lifted a little on December 20 and on December 22, when strong winds were seen. From December 23, the city saw a 36-hour long fog spell that finally ended on the morning of December 25,” said RK Jenamani, director in charge, IGI Airport Met Centre.
According to Met officials, a new satellite — Insat 3-D — has helped massively in detecting fog at very high resolution up to one kilometre and has helped in now casting (whereby the situation at that time can be assessed) the movement of fog patches to the airport.
The number of flight diversions this year was also lesser as compared to previous years.
“In December, only 46 flights were diverted despite such dense fog and CAT III conditions. Better coordination with airports and airlines ensured this,” said Jenamani.
The Met Department issued fog updates every 30 minutes to pilots and the Air Traffic Control for broadcast to all aircraft for landing, take-off and planning during fog hours to help rescheduling or delaying of flights.