Flight operations remained unaffected at the Indira Gandhi International airport in New Delhi for the third consecutive day on Friday even as the airport experienced fog.

Though there was fog on Thursday night and Friday morning, it did not affect flight operations. Fog started to descend on the airport from 10pm on Thursday night and the runway visibility at the third runway reduced to 700 metres but on the main runway it was 1,200 metres.

"The visibility dipped on the runway between 2am and 5am, but as it was way above the required minimum of 125 metres and 150 metres for small and large aircraft, there was no disruption," airport sources said.

"Arriving flights had to use the various categories of instrument landing system to land," they said.

"Flight operations were badly hit due to dense fog early this week leading to delay, cancellations and diversions of over 300 flights.But for last two days, operations are normal despite moderate to shallow fog at the airport," they said.