Air operations remained disrupted for the fourth consecutive day on Saturday at New Delhi's Indira Gandhi International airport due to dense fog, with schedules of over 50 domestic and international flights badly affected.
Three morning flights were cancelled, while 32 domestic and 20 international ones were delayed by over three to four hours as thick fog blanketed the airport.
Fog began to descend upon the airport late on Friday night and the visibility started to deteriorate, forcing the airport authorities to implement low visibility procedures.
The runway visibility dipped to a low of 75 metres at approximately 3.30 am and again at 7.30 am on Saturday morning. Due to the poor visibility, some flights had to land with the help of CAT-III B instrument landing system.
Though CAT-III B compliant aircraft managed to land, flights could not take off as the runway visibility was less than 150 metres, the required minima for the low visibility take-off for an aircraft, an airport official said.
A new rule by the Directorate General of Civil Aviation, which has fixed the LVTO at 150 metres for all aircraft, was preventing flights from taking off when the visibility was 125 metres.
"Now, we cannot take off until the visibility is more than 150 metres, even if we are capable of taking off when the runway visibility is just 125 metres," said a pilot with Air India.