Delhi: At least 100 flights delayed, two diverted as heavy fog envelops the capital

According to airport authorities, at least 100 flights were delayed and two were diverted from Delhi to another route due to Delhi's dense fog early Tuesday morning. The visibility at Delhi's Indira Gandhi International Airport dropped to less than 200 metres on Tuesday morning.A 'delay' is defined as a deviation of more than 15 minutes from the scheduled time of arrival or departure.

Airport officials reported that two flights, one SpiceJet flight around 11:45 pm and another IndiGo flight at 2:15 am, both were diverted to Jaipur due to heavy fog this season.

"In both cases, the pilots were not CAT-III B compliant and therefore, were not given permission to land at the airport. During this period, visibility was around 50 metres and the ATC guided both flights to the nearest airport, which is Jaipur", said an airport official.

When visibility falls below 800 metres, the airport initiates low visibility procedures (LVP), which are measures designed to make landing easier for flights. CAT-I procedures are in effect during this time, which is the most basic set of precautions to guide pilots in landing. Only CAT-II compliant flights and pilots are permitted to land when visibility is less than 550 metres, while CAT-III A pilots are permitted to land when visibility is between 175 and 300 metres. CAT-III B qualifications are the most stringent for a pilot to land a flight, allowing them to land even when visibility is less than 50 metres.

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While flights can still land at the airport when visibility is 50 metres, no flights are allowed to depart unless the runway visibility range (RVR) is 125 metres. “This led to some arrivals and departures being delayed,” an official said.

A Met official said visibility was at its worst at the airport between 3:30 am and 7:30 am, "During this four-hour window, visibility at both Palam and Safdarjung was 50 metres, with CAT-III B procedures in place. It increased to 100 metres at 7:30 am and then increased substantially to over 500 metres by 9:30 am", the official said.

Forecasts suggest that Delhi is likely to see more dense fog in the next two days, especially on New Year's Eve.

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