Fog cover enveloped the Chennai airport’s runway today morning and hung in the air till 8 am causing at least 12 flights to be delayed by 45 minutes to an hour. The duty officer at the Meenambakkan-based RMC office said, “This is the first time this season that we are seeing such a thick cover of fog in the city, this season. It is because the atmosphere has been stagnant and wind movement has been minimal. It may not occur again for a few days, but similar conditions are expected around Pongal,"