Thick fog enveloped the Indira Gandhi International Airport on Monday morning delaying some flights.
Low visibility procedures were initiated at the airport in the wee hours after fog started setting in and some flights took off and landed at the airport using the CAT III Instrument landing System (ILS), IGI officials said in New Delhi.
The CAT III ILS allows compliant aircraft and trained pilots to land even when the runway visibility is down to 50 meters.
Some flights were delayed due to the dense fog, airport sources said.
Airport authorities say they have taken several proactive measures to minimise inconvenience to passengers and ensure continuity of flight operations during low visibility conditions because of fog.
130 parking bays have also been provided with CAT III compatible lighting systems and trained traffic marshals with equipment are being deployed at taxiways and vehicular lane crossings for better efficiency and safety.
The IGI Airport has augmented its round-the-clock call centre, which will share the latest flight information, which can be accessed from the airport's website also.