New Delhi: Flight operations were once again badly hit as dense fog enveloped IGI airport on Friday affecting the schedule of over 200 domestic and international flights, causing inconvenience to the travelers.

Over 200 flights were delayed, 28 were cancelled and 19 domestic and international flights were diverted to Jaipur, Lucknow, Ahmedabad and Mumbai, an airport official said.

Most of the flights were delayed as the fog reduced the runway visibility below the prescribed limit for low visibility take-off of 125 metres and 150 metres for small and big aircraft.

The fog started to descend at the airport around 2.30 AM, though shallow fog was there since late last night.

The fog was so dense that general visibility dipped to almost zero, while the runway visibility hovered between 75 and 50 metres between 2.30 AM and 3.30 AM, the official said.

Due to this, a Jet Airways flight from Dubai and an Air India flight from Muscut had to be diverted to Jaipur.

The Boeing 737 Jet Airways plane (9W 547) was approaching to land but the pilot reported to the ATC tower that he was unable to see the runway and was diverted to Jaipur.

"The Boeing 737 plane did a 'go around' but could not return to Delhi as dense fog had set in. Hence the flight was diverted to Jaipur and returned to Delhi at 1340 hours. The aircraft and crew were CAT III certified as per DGCA regulations," a statement from the airlines said.

With the runway visibility dipping below 800 metres, the airport authorities implemented low visibility procedures at main runway (28/10) at 1.33 AM while at new runway (29/11) at 3.11 AM.

The runway visual range remained between 100 metres and 125 metres for about five hours, between 4 AM and 9 AM, due to which most of the flights could not take-off, due to LVTO restrictions.

The visibility improved for sometime when a few flights took off but most of the flights could not. Though some flights landed using CAT-IIIB instrument landing system, an airport official said.

The LVP remained implemented on new and main runways till 1250 hours. A total of 187 flights operated using various categories of ILS.

A total of 57 flights operated using CAT-I, 3 with CAT-II and 127 with CAT III ILS.

Met Department has predicted dense fog at the airport on Saturday also.

"But it will be of lesser duration and is likely to happen from 5AM and may remain till 9 AM on Saturday," R K Jenamani, Airport Met Director, said.

The airport has witnessed dense fog on December 29 and 30 and January 17 and 18.