Winter fog disrupts flights again; data shows it’s a familiar seasonal pattern

Fog disruptions are common in December-January

Winter fog has once again tightened its grip on India’s aviation network, with more than 300 flights cancelled in just three days. While the scale of disruption feels exceptional, historical data shows this is a recurring seasonal pattern - dense fog routinely throws airline schedules off track every winter, making December and January the most disruption-prone months of the year.

Over the past several years, weather has consistently been the single biggest driver of flight cancellations during the winter season.

In December 2022-January 2023, weather-related issues accounted for 83.8 percent of all cancellations. The following winter, December 2023-January 2024, saw a similar pattern, with weather responsible for 73.9 percent of cancellations.

Even in winters with relatively fewer cancellations, the dominance of weather remains clear. Weather accounted for 60.5 percent of cancellations in December 2019-January 2020, and 62 percent in December 2016-January 2017.

The intensity of winter disruption has fluctuated depending on fog severity and operational preparedness. The weather-related cancellation rate peaked at 1.93 percent in December 2023-January 2024, the highest in recent years. By contrast, winters such as December 2017-January 2018 and December 2018-January 2019 saw milder disruption, with cancellation rates of 0.53 percent and 0.58 percent, respectively.

Airports and airlines have expanded CAT-III landing systems, improved crew training and refined winter operating protocols over the years, helping cushion the impact of fog to some extent. However, passenger volumes have risen sharply, meaning that even a small percentage increase in cancellations now translates into large absolute numbers of affected flights and passengers.

With January still ahead, historically one of the foggiest months of the year, airlines and aviation authorities are likely to remain on high alert. For passengers, the outlook remains uncertain, especially after IndiGo’s operational disruptions in December, which had already triggered widespread cancellations.

Data shows that operational disruptions have also been on the rise during December and January, with the ratio of cancellations due to operational problems rising to a four-year high of 6.7 percent compared with 3.8 percent the previous year.