As many as 66 flights were cancelled at the Delhi airport on Friday due to fog and low visibility conditions, PTI reported citing sources.Several airlines cancelled flights to and from the national capital as reduced visibility disrupted operations. Of the total cancellations, 32 were arrival flights while 34 were departures, the source said.The aviation regulator has designated the period from December 10 to February 10 as the official fog window for the winter season, during which special operational measures are required to ensure flight safety.As part of the Directorate General of Civil Aviation’s (DGCA) fog-related operational norms, airlines are mandated to roster pilots trained to operate in low-visibility conditions and deploy Category-IIIB-compliant aircraft for operations during dense fog.Category III is an advanced navigation system that enables aircraft to land in poor visibility conditions. Category III-A allows landings with a runway visual range (RVR) of up to 200 metres, while Category III-B permits landings with an RVR of less than 50 metres.
