Dense fog and subsequent drop in visibility is causing flight delays at Delhi’s Indira Gandhi International Airport prompting airlines to adjust schedules.

The airport issued a passenger advisory on Friday warning of flight disruptions and advised passengers to check flight status in advance.

The advisory stated, “Due to prevailing dense fog conditions, flight operations are currently being managed under CAT IIl conditions, which has led to disruptions in flight schedules.”

Urging passengers to check with their airlines for the latest flight status, the advisory added, “ Please rest assured that our staff are actively coordinating with all stakeholders to assist passengers and provide necessary support across all terminals. For real-time flight updates, please reach out to your respective airlines. We sincerely regret any inconvenience caused and appreciate your understanding.”

Several airlines issued travel advisory amid dense fog over Delhi, including IndiGo, Air India, Air India Express and SpiceJet.

CAT III procedures allow aircraft to land safely in extremely low visibility.

Notably, there are a total of six airports in India where runway is certified for CAT III operations, including Delhi, Lucknow, Jaipur, Amritsar, Bengaluru and Kolkata.

India Meteorological Department (IMD) issuing a red alert for Delhi and warning that road, rail and air traffic may be affected.

IMD officials said satellite imagery showed a dense fog cover over Punjab, Haryana, Delhi, Uttar Pradesh, northeast Madhya Pradesh and Bihar.

The IMD issued a red alert for Delhi, warning that fog may disrupt operations at some airports and affect highways and railway routes.

An orange alert was issued for several districts in Uttar Pradesh, including Agra, Aligarh, Baghpat, Bareilly, Bijnor, Bulandshahr, Etah, Etawah, Firozabad, Gautam Buddha Nagar, Ghaziabad, Hapur, Hathras, Mathura, Meerut, Moradabad, Muzaffarnagar, Pilibhit, Rampur, Saharanpur, Shahjahanpur and Shamli.

Haridwar and Udham Singh Nagar in Uttarakhand and Amritsar, Fatehgarh Sahib, Gurdaspur, Patiala and Sangrur in Punjab are also under an orange alert.

The IMD warned of difficult driving conditions and an increased risk of road accidents, adding that there is a possibility of power line tripping in affected areas.

"Residents in the affected regions are advised to stay alert and take necessary precautions, including being careful while driving or travelling by any mode of transport, using fog lights, checking road and traffic conditions, staying in touch with airlines, railways and state transport authorities for travel schedules, avoiding unnecessary travel and following advisories issued by concerned agencies," the IMD said.

Over the past few days dense fog and smog have been disrupting flight operations at Delhi’s Indira Gandhi International Airport prompting airlines to adjust schedules amid delays.

The Ministry of Civil Aviation issued a heavy fog alert for northern India, advising passengers to check flight status before travelling and to allow additional travel time to avoid inconvenience.

MoCA in a post on X stated, “The ongoing fog conditions in Northern India are impacting airport operations. Passengers are advised to stay in touch with their airlines for real-time flight updates, regularly check official airline and airport websites or apps, and plan their journeys with additional travel time to avoid inconvenience. Passenger facilitation teams are deployed across airports to provide necessary assistance.”

On 18 December, IndiGo issued passenger advisory as dense fog affected flight operations at Chandigarh, Ranchi, Patna, Gorakhpur and Varanasi airports.

Air India Express' multiple flights to and from Delhi were cancelled on Thursday amid low visibility due to dense fog.

Dense fog keeps visibility low

Early morning visibility was low in parts of the national capital on Friday due to a thick layer of smog and haze, with mercury levels settling at 9 degree Celsius.

Delhi's air remained in the 'very poor' category, with the 24-hour average Air Quality Index (AQI) settling at 382, edging closer to the 'severe' category.

According to the Central Pollution Control Board's SAMEER app, out of 40 air quality monitoring stations across the city, 14 recorded severe air quality while 26 were in the very poor category. Vivek Vihar recorded the worst air quality with an AQI of 434, the data showed.

As per the Central Pollution Control Board's classification, an AQI between zero and 50 is considered good, 51 to 100 satisfactory, 101 to 200 moderate, 201 to 300 poor, 301 to 400 very poor and 401 to 500 severe.

The Air Quality Early Warning System for Delhi has forecast that air quality is likely to remain in the 'very poor' category till Saturday and deteriorate to 'severe' on Sunday.

Several parts of the national capital were seen enveloped in dense smog during the early morning hours, leading to reduced visibility.

According to the India Meteorological Department, the minimum temperature settled at 9 degrees Celsius, while relative humidity stood at 100 per cent.

The maximum temperature is expected to hover around 21 degrees Celsius, with dense fog likely to persist through the day.