Despite fog-ready pilots and airports, flights disruptions abound

The thick blanket of fog that has cloaked cities in north India has grounded or delayed scores of flights in the past three days.

More than 100 flights were delayed on Wednesday and at least 58 others were diverted between December 25 and 6am on Thursday, causing much duress to flyers.

While flight disruptions are not uncommon during the fog season, the intensity of messed-up airline schedules has put the spotlight on whether the problem could have been mitigated. That is because at least six Indian airports, including Delhi where disruptions were acute, are equipped with plane landing systems that enable the so-called CAT IIIB landings. These are mostly automatic landings that use a combination of powerful radio signals and sophisticated runway lighting, allowing planes to land even when visibility is as low as 50 metres during rains, snow and of course, dense fog.

There is also no shortage of trained pilots. India currently has 4,804 pilots—2,979 captains and 1,825 co-pilots—trained to land in fog.

Yet, disruptions of hundreds of flights have continued unabated.

Why?

Some airlines were accused by Delhi airport officials of not rostering CAT III complaint pilots to land in Delhi. Did the airlines underestimate the intensity of the fog this year?

Flogs affect several airports across the world, but typically last only a few days. India is plagued by longer bouts. The two months from December 10 and February 10 are usually considered as a fog period in India.

That said, airlines operate under the assumption that fog settles in between 9 pm and 10 am. The so-called red-eye flights that depart late at night are few in India. Which means that airlines usually roster their pilots for the morning flights and for airports in the north.

This year, two factors put paid to those plans. One, the fog that settled in the morning hours failed to lift, upsetting not only early departures but also evening and night departures. Two, poor visibility due to fog, customarily a North Indian phenomenon, was also observed in the south, in the Hyderabad and Bengaluru airports.

IndiGo, Vistara and Air India did not comment for this article.

Privately, airline officials blamed the increased flight disturbances this year on the—only—one CAT III compliant runway that was operational at the Delhi airport. Three other runways at the Indira Gandhi International Airport that are CAT III compliant are under repair.

“If only one runway is available for landing at the country’s biggest airport, it will lead to consequential flights delays and even diversions,” a airline official said, asking not to be named.

A Delhi airport official said that the other runways would be made operational from early next week.

Airlines are often blamed for dodging the fog problem because of the costs involved.

Airlines are accused of shying away from equipping planes with CAT IIIB instruments or training pilots because of costs.

Airline officials disagree. An airline spends not more than ₹3 lakh to make a pilot CAT III compliant, said a former pilot, requesting anonymity. “That is not very expensive.”

That apart, aviation regulator DGCA has been pressing airlines and airports take actions to prepare for fog. DGCA asks airlines to eliminate non-CAT II/CAT III compliant aircraft from flight schedules and ensure rostering CAT III qualified cockpit crew.

Thanks to these measures, the number of flight disruptions during winter have dropped in recent years. In 2021-22, only 124 flights were cancelled out of 136374 total aircraft movements. That amounted to a 0.09% rate of cancellations. That figure declined to 86 cancellations for 166927 total aircraft movements in 2022-23, or a 0.05% rate of cancellations.

Similarly, in 2021-22, 58 flight diversions took place, which declined to 14 in 2022-23. This is despite a 22% increase in the number of aircraft movements in the past two years.

Airlines pay a price when flights are stalled or cancelled. They have to offer passengers free food and drinks on a stalled flight, accommodate them in another, or refund tickets for cancelled flights.

“An airline bears massive costs when it has to divert a flight, “ said an official of another airline, seeking anonymity.