According to IGI officials, low visibility procedure (LVP) was implemented at 11 pm on Thursday, but only runway 28 was used for both departures and arrivals till 6 am on Friday. Officials cited some problem with the Instrument Landing System (ILS) of the new runway 29, which also experiences denser fog because of large open spaces around it.

LVP lasted for more than 9 hours, during which 95 flights (including 46 domestic and 49 international) operated. LVP was terminated at 7.55 am on Friday when RVR on runway 28 was 1,800 m and 1,200 m on runway 29.

At least 70 flights were delayed on Friday on account of low-visibility conditions. One Jet Airways flight from Singapore was diverted to Ahmedabad, five others were rescheduled and 13 had to be cancelled, including G8-341 to Hyderabad, IT-302 to Mumbai, 6E -101 to Bangalore, S2-101 to Mumbai and 9W-3319 to Lucknow.

“G8-451 from Delhi to Mumbai, 6E-201 from Delhi to Imphal, GF-130 Delhi to Bahrain, GF-131and EK C 513 from Delhi to Dubai were rescheduled due to bad weather at the Delhi Airport,” an airport official said.

“The fog this year, coupled with strong winds, is of a variable nature. This fog characteristic is being witnessed in Delhi for the first time —visibility gets completely cleared almost instantly, followed by a fresh spell of dense fog,” an official said.

IGI Met Department said there were fluctuations in the runway visual range (RVR), which made it difficult to function. “General visibility fluctuated between 0 to 200 m from 11.30 pm on Thursday night till about 6 am on Friday morning. The fog finally lifted with strong winds around 6.30 am,” R K Jenamani, director-in-charge, IGI Met Department, said. According to Jenamani, Category-III fog is being experienced, but not in the usual way, since Thursday.