A dense blanket of fog enveloped the New Delhi airport on Friday morning, disrupting air and rail traffic.

Flight services were severely hit for the first time this winter as airlines had to either reschedule or cancel a number of services to destinations like Mumbai, Bangalore, Kolkata, Nagpur, Ahmedabad and Jammu.

While the normal visibility dropping to around 50 metres early in the morning, the runway visibility range plummeted to 75 metres at 3:30 am, prompting airport officials to switch to the sophisticated CAT III-B landing system, airport and meteorological department officials said.

The RVR gradually improved to 400 metres and normal visibility to 200 metres at around 9 am, they said, adding the low visibility procedure was initiated at the airport at 2:40 am when the RVR dropped to 1,400 metres, they added.

After the LVP was initiated, there were 11 arrivals of international flights and 13 departures, airport officials said.

Out of the 11 arrivals, five landed at the airport under CAT III-B conditions when the RVR was between 50 m and 200 m and two under CAT-III A when the RVR was between 200 m and 350 m.

Seven international and three domestic flights were diverted from Delhi. Five flights were diverted to Mumbai.

Seven international arrival and seven departure flights were delayed, an airport official said, adding an international flight to Kathmandu was cancelled.

Twenty eight domestic arrivals and departures each were also delayed due to the fog by10:30 am, the official said.

The minimum temperature in the national capital on Friday was 9 degrees Celsius.