Operations almost came to a complete halt around 10 pm after runway visibility dipped to less than 75 metres, which is the minimum required visibility condition for an aircraft to land using CAT IIIB instrument landing system.
The national capital experienced the season's worst fog on Sunday evening with the maximum temperature settling one notch below average at 19.3 degrees Celsius.
Delhiites woke to a nippy and foggy Monday morning with visibility dropping to around 400 metres. Dense fog led to diversion and delay of flights. Trains pulling into Delhi were also running behind schedule. Here are some images of a foggy morning in Delhi.
Dense fog returned to the capital on Sunday after a four-day lull, affecting over 130 flights.
Passengers would be provided accurate information about flights through Flight Information Display System at the airport terminal.
A total of 57 flights operated using CAT-I, 3 with CAT-II and 127 with CAT III ILS.