The Ministry of Civil Aviation on Monday issued a travel advisory after multiple flights were delayed due to a thick layer of smog and fog across northern parts of India. The ministry also shared customer support numbers of various airlines, warning passengers of potential disruptions.

In a post, the ministry said: "Due to fog conditions across parts of Northern India, flight operations at select airports may be impacted, leading to possible delays. Passengers are advised to stay updated through official airline communication channels, allow additional time for airport arrival and check-in procedures, and plan their travel accordingly."

At least 128 flights were cancelled, eight got diverted, and nearly 200 services were delayed at the Delhi airport due to dense fog on Monday.

An official said 64 departures and 64 arrivals were cancelled, while eight flights got diverted due to dense fog and low visibility conditions at the Delhi airport.

Information on the flight-tracking website Flightradar24.com showed that nearly 200 flights were delayed, with an average departure delay of around 24 minutes.

Meanwhile, Delhi airport said flight operations were being conducted under CAT III conditions because of dense fog, raising the likelihood of delays and cancellations.

In a passenger advisory posted on X at 9 am, the airport said: "Flight operations are currently being carried out under CAT III conditions due to dense fog, which may lead to delays or cancellations. Our ground teams are on-site and actively assisting passengers to ensure a smooth travel experience. For the latest flight updates, please reach out to your respective airlines. We sincerely regret for any inconvenience caused."

An hour later, the airport issued another update stating: "Due to persistent dense fog, flight operations continue to remain under CAT III conditions which may result in flight delays. For the most up-to-date flight information, we request you to contact your respective airlines or visit our website. Our teams are working closely with all stakeholders to minimize inconvenience to passengers. We sincerely regret the inconvenience caused and appreciate your understanding."

Airlines also issued advisories, urging passengers to check flight status before heading to airports.

IndiGo said fog continued to affect visibility and flight movements across Delhi and several airports in northern India.

The airline wrote on X: "Fog continues to persist across Delhi and several airports in northern India. Visibility remains reduced and, as a result, flight movements are presently slower than normal, with some delays being experienced."

It added: "We will continue to manage operations under the prevailing conditions, sequencing departures and arrivals to maintain orderly operations."

IndiGo further advised passengers: "We request you to keep a check on your flight status via http://bit.ly/3ZWAQXd. As fog continues to affect road visibility and traffic conditions, we recommend allowing some additional time for your journey to the airport. Please be assured that our teams are right here to support you at the airports and remain ready to assist you throughout your journey today."

Air India said it had taken proactive measures to minimise disruption.

In a post on X late Sunday night, the airline said: "Weather forecast for tomorrow morning indicates dense fog with low visibility in parts of northern India, including Delhi, which is likely to impact flight operations."It added: "We have taken proactive steps to minimise disruptions (learn more at http://bit.ly/4agYVyF). However, in the event of unexpected delays, diversions, or cancellations, please rest assured that our ground teams will extend all necessary assistance."

Highlighting its passenger support measures, Air India said: "In addition, our ‘FogCare’ initiative allows passengers booked on certain flights that are likely to be affected during the fog window to receive advance alerts on their registered phone numbers, with the option to change their flights without any extra payment or seek a full refund on their bookings without any penalty."

The airline also advised passengers: "If you are flying with us tomorrow, we encourage you to check your flight status here before heading to the airport and allow extra time for your journey: https://airindia.com/in/en/manage/flight-status.html. We thank you for your patience and understanding. The safety and well-being of our passengers and crew remain our highest priority."

SpiceJet also issued a weather update late Sunday night, saying: "#WeatherUpdate: Due to bad weather (poor visibility) in Delhi (DEL), all departures/arrivals and their consequential flights might get affected. Passengers are requested to keep a check on their flight status via http://spicejet.com/#status."

The flight disruptions coincided with deteriorating air quality in the national capital. According to PTI, Delhi remained shrouded in a thick blanket of smog on Monday morning, with the average Air Quality Index (AQI) settling in the ‘severe’ category at 402.

Data from the Central Pollution Control Board showed air quality was ‘severe’ at 22 stations, ‘very poor’ at 14 and ‘poor’ at one station. Vivek Vihar in east Delhi recorded the highest AQI at 456, while data from three stations was unavailable.

The Air Quality Early Warning System said Delhi’s air quality is likely to remain in the ‘very poor’ category over the next three days and fluctuate between ‘very poor’ and ‘severe’ over the subsequent six days.

Dense fog at isolated locations also affected vehicular movement in the morning. According to the India Meteorological Department, minimum temperatures are expected to remain near normal, while maximum temperatures will be above normal, with light northwesterly winds below 15 kmph gradually weakening later in the day.