Abstract The present study considers horizontal visibility as a hazard parameter due to airport operational activities during December, January, and February (2018–2025). The fog conditions were maximum in 2023 and minimum in 2019. It is found that dense fog conditions formed during the early hours, and 9.4% and 8.8% of the fog events prevailed at 0200 UTC and 0100 UTC, respectively. However, fog disappeared due to solar insolation till 1200 UTC and again occurred during the later part of the day, from 1800 UTC to 2300 UTC. Fog engulfed the airport during dense/very dense fog conditions; the aviation sector was affected including delays, cancellations, and diversions due to a sudden drop in visibility. The month of January (with 54.3% of fog events during the study period) was highly susceptible to low cloud cover development, which subsequently reduced the horizontal visibility even up to zero meters and caused the imposition of the low visibility procedure (LVP), in which non-essential activities were suspended on the airfield. Almost every year, shallow fog conditions had the highest duration, with a maximum from 2020 to 2023, when the maximum total fog duration was reported. The dense and very dense fog conditions had relatively the lowest and stable duration from 2018 to 2025, except for 2019, which recorded the lowest number of dense and very dense fog condition instances, but had the potential to disrupt aviation services. The bootstrapped slope estimates were computed to examine the horizontal visibility thresholds, such as below 50, 500, 800, and 1000 m, which are crucial and efficient for airport operations. The mean slope was found to be maximum for 1000 m threshold, +66.55 (days/year) but having low confidence; strong for 800 m (+50.69 days/year); slight increase for below 50 m threshold (+4.80 days/year), for 200 m threshold (+17.79 days/year); and moderate increase for 500 m horizontal visibility (+32.87 days/year) but not statistically significant. In the present study, analysis showed that the dense/very dense fog was formed when the relative humidity exceeded 82%, dew point depression was less than 2°C, and wind speed was in the range of 0–2 knots. Research Highlights <UnorderedList Mark="Bullet"> <ItemContent> The seasonal breakdown revealed that fog events are most frequent in December and January with interannual variability. The maximum fog episodes occurred in winter 2023 and minimum in winter 2019, with dense fog most frequently onsetting in the early morning hours (about 9.4% at 0200 UTC, 8.8% at 0100 UTC); fog dissipated by midday but returned in the evening, repeatedly impacting flight schedules due to sudden drops in visibility. </ItemContent> <ItemContent> January had the highest proportion of fog events (54.3%), frequently requiring Low Visibility Procedures due to very low cloud cover and horizontal visibility often dropping to zero. Shallow fog lasted longest every year, peaking from 2020 to 2023, while dense and very dense fog durations were relatively stable (except 2019, with the fewest such events), but still disrupted aviation. </ItemContent> <ItemContent> The steepest increase in days was for the 1000 m horizontal visibility threshold (+66.55 days/year, low confidence), and dense fog typically formed when relative humidity exceeded 82%, dew point depression was under 2°C, and wind speeds were 0–2 knots. </ItemContent> <ItemContent> To explain the impacts of fog over CCSI Airport, the two fog episodes from 28 December 2023 to 3 January 2024, and 11–15 January 2024, were also included. The diversions, cancellations during these fog episodes underscore the operational challenges during dense fog conditions at CCSI Airport and highlight the broader impact on air travel in northern India during peak winter. </ItemContent> </UnorderedList>

Assessment of winter fog conditions at CCSI Airport, Lucknow, India (2018–2025)

期刊论文
发表日期：

2026年7月21日

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Preeti,
Shashi Kant

摘要

Abstract

The present study considers horizontal visibility as a hazard parameter due to airport operational activities during December, January, and February (2018–2025). The fog conditions were maximum in 2023 and minimum in 2019. It is found that dense fog conditions formed during the early hours, and 9.4% and 8.8% of the fog events prevailed at 0200 UTC and 0100 UTC, respectively. However, fog disappeared due to solar insolation till 1200 UTC and again occurred during the later part of the day, from 1800 UTC to 2300 UTC. Fog engulfed the airport during dense/very dense fog conditions; the aviation sector was affected including delays, cancellations, and diversions due to a sudden drop in visibility. The month of January (with 54.3% of fog events during the study period) was highly susceptible to low cloud cover development, which subsequently reduced the horizontal visibility even up to zero meters and caused the imposition of the low visibility procedure (LVP), in which non-essential activities were suspended on the airfield. Almost every year, shallow fog conditions had the highest duration, with a maximum from 2020 to 2023, when the maximum total fog duration was reported. The dense and very dense fog conditions had relatively the lowest and stable duration from 2018 to 2025, except for 2019, which recorded the lowest number of dense and very dense fog condition instances, but had the potential to disrupt aviation services. The bootstrapped slope estimates were computed to examine the horizontal visibility thresholds, such as below 50, 500, 800, and 1000 m, which are crucial and efficient for airport operations. The mean slope was found to be maximum for 1000 m threshold, +66.55 (days/year) but having low confidence; strong for 800 m (+50.69 days/year); slight increase for below 50 m threshold (+4.80 days/year), for 200 m threshold (+17.79 days/year); and moderate increase for 500 m horizontal visibility (+32.87 days/year) but not statistically significant. In the present study, analysis showed that the dense/very dense fog was formed when the relative humidity exceeded 82%, dew point depression was less than 2°C, and wind speed was in the range of 0–2 knots.

Research Highlights

The seasonal breakdown revealed that fog events are most frequent in December and January with interannual variability. The maximum fog episodes occurred in winter 2023 and minimum in winter 2019, with dense fog most frequently onsetting in the early morning hours (about 9.4% at 0200 UTC, 8.8% at 0100 UTC); fog dissipated by midday but returned in the evening, repeatedly impacting flight schedules due to sudden drops in visibility.

January had the highest proportion of fog events (54.3%), frequently requiring Low Visibility Procedures due to very low cloud cover and horizontal visibility often dropping to zero. Shallow fog lasted longest every year, peaking from 2020 to 2023, while dense and very dense fog durations were relatively stable (except 2019, with the fewest such events), but still disrupted aviation.

The steepest increase in days was for the 1000 m horizontal visibility threshold (+66.55 days/year, low confidence), and dense fog typically formed when relative humidity exceeded 82%, dew point depression was under 2°C, and wind speeds were 0–2 knots.

To explain the impacts of fog over CCSI Airport, the two fog episodes from 28 December 2023 to 3 January 2024, and 11–15 January 2024, were also included. The diversions, cancellations during these fog episodes underscore the operational challenges during dense fog conditions at CCSI Airport and highlight the broader impact on air travel in northern India during peak winter.