New Delhi: Delhi witnessed the first fog of the winter season today which delayed the schedule of over 25 domestic and international flights at the IGI Airport here.

The flights were delayed as the runway visibility dropped to less than 50 metres, bringing landing and take-off to a halt for over an hour, an airport official said.

This is the first fog of the winter season, which started to descend at the airport early in the morning, but as the day progressed it become dense.

Flights scheduled to land at Delhi airport were asked to hover after the runway visibility dropped to less than 50 metres, the minimum visibility range for a CAT III B complaint aircraft to land in the poor visibility conditions.

Around 10 planes, coming to Delhi where asked to hover, while one of the international flight from Amman was diverted, airport sources said.

As the visibility increased to 75 metres on the main runway (28/11), some of the CAT-III B complaint aircraft were allowed to land but no flights were departing.

Meteorological department has predicted the fog may clear after 10 am and flights could take off after that.

The general visibility at the three runways were around 150 metres while the runway visibility was between 65 to 75 metres on all off them.

The two runways of IGI airport are CAT-III B complaint, which means if the runway visibility is upto metres, flights can land.

But for take-off, the minimum visibility is around 125 metres and 150 metres, depending upon the size of the aircraft.