Operations of 50 flights were affected due to fog at the Kolkata international airport since Friday night. Airport sources said air traffic was stalled from 11.30 p.m. last night to 8.50 a.m. this morning. An Emirates flight was the first to land at the airport at 8.50 this morning. Thirty outgoing flights could not take off since last night and 20 incoming flights were not able to land in Kolkatta due to the fog. The visibility range at the airport till 8.50 a.m. was around 50 metres.