Thick fog on the last day of 2017 affected flight operations at Indira Gandhi International Airport today. As visibility fell below the minimum needed for flight operations, landings and take-offs were stopped for a few hours, airport officials said. All domestic and international flights at Delhi airport were put on hold between 8 am and 10 am on all the three runways after visibility fell below 50 metres -- less than the minimum needed for flight operations -- due to dense fog. Some flights were also cancelled.