Dense fog disrupted air operations at the IGI airport here for the sixth consecutive day on Sunday, throwing schedules of around 50 domestic and international flights out of gear and causing inconvenience to the fliers.

Over a dozen domestic morning flights to Chandigarh, Bangalore, Aurangabad and Mumbai were cancelled, 18 inbound and outbound international flights were delayed by over three to four hours while four flights were rescheduled, an airport official said.

Fog started to descend over the airport at around 10.30 pm last night and become thicker by 3.30 am when the runway visibility dropped to 200 metres, forcing the airport authorities to implement the low visibility procedures (LVP).

The runway visibility further deteriorated to 100 metres by 5.30 am and some of the flights arrived here using CAT-IIIB instrument landing system (ILS).

Visibility continued to fluctuate between 100 metres and 175 metres, due to which the Air Traffic Control did not clear the flights for take-offs.

Reducing the low visibility take-off (LVTO) limit by the DGCA has hit airlines like Air India and IndiGo hard which were capable to taking off when the visibility was 125 metres.

“Our first flight, which was scheduled to take-off at around 6 am, could take-off around 8.30 am due to LVTO restrictions,” said an Air India official.