Why a Morning Fog in Guwahati Delayed an IndiGo Bagdogra-Calcutta Flight

Passengers on IndiGo's Bagdogra-Calcutta flight 6E 6135 faced confusion and a significant delay. The Sunday evening flight was delayed by over an hour, finally taking off at 9:10 pm. The stated reason was "bad weather," yet no fog was present at either Bagdogra or Calcutta airports. The actual cause was a sequential flight delay that began hundreds of miles away in the morning.

The Cascading Effect of India Winter Fog

A sequential delay happens when an aircraft's first flight of the day is delayed. This initial delay then carries over to all subsequent flights operated by the same plane. This chain reaction affects passengers even at airports with clear skies. In this case, the aircraft's first flight from Ahmedabad to Guwahati was delayed by almost two hours due to fog. The delay then impacted flights across multiple cities, including Dibrugarh, Calcutta, Patna, and finally Bagdogra.

Calcutta airport officials noted that this cascading effect is common during the fog season. They also stated that while this affects all carriers, the impact is larger on IndiGo due to its extensive Indian aviation network.

Operational Challenges and Regulatory Response

The typical turnaround time for a domestic IndiGo flight is only 30-40 minutes. This tight schedule makes it hard to recover from an initial delay. Operational teams must consider factors like flight duty time limitations for pilots. They must also balance safety against the need to recover the schedule.

The Directorate General of Civil Aviation (DGCA) has designated the official India winter fog window as December 10 to February 10. The DGCA mandates airlines to use aircraft and pilots compliant with CAT III Instrument Landing Systems (ILS). CAT III-B systems allow landings in low visibility operations (LVO), down to a Runway Visual Range (RVR) of under 50 meters.

In response to widespread disruptions, the DGCA issued new DGCA flight regulations. Airlines must now cancel flights expected to be delayed by over three hours. They must also provide real-time updates to passengers. Furthermore, DGCA rules require airlines to provide refreshments for delays of two to four hours and full meals for delays over four hours.

Airline Mitigation Strategies

IndiGo acknowledged the challenges, stating that adverse weather in North Indian cities leads to poor visibility. They noted that their extensive network makes managing resources complex during fog conditions. The airline also cited infrastructure limitations and airport congestion as factors.

Air India has activated its annual "Fog Care" initiative. This program identifies likely affected flights in advance based on forecasts. Passengers are then alerted about possible disruptions. Air India also offers options to change flights or receive a full refund without penalty for affected travelers.

• Key Takeaways for Passengers
• Sequential delays are a major cause of disruption, even in clear weather.
• The DGCA has a strict fog window from December 10 to February 10.
• Airlines must deploy CAT III-compliant aircraft and crew for low visibility operations.
• Passengers are entitled to refreshments and real-time updates under DGCA flight regulations.

For more insights into airline operations and the latest commercial aviation news, visit https://flying.flights.