Mumbai/ New Delhi, Dec 3 (PTI) IndiGo cancelled more than 100 flights at various airports, and scores of services were delayed on Wednesday as the country's largest airline grappled with significant operational disruptions mainly due to crew shortage.

Aviation watchdog DGCA said it is investigating IndiGo flight disruptions and has asked the airline to submit the reasons for the current situation as well as the plans to reduce flight cancellations and delays.

As part of the calibrated adjustments announced by IndiGo, there will be cancellations and rescheduling of flights, sources said on Wednesday, a day when airports witnessed chaos as hundreds of passengers faced hardships due to services getting cancelled and delayed for long.

The airline, which operates around 2,300 domestic and international flights daily, on Wednesday said a "multitude of unforeseen operational challenges" have significantly disrupted its operations across the network for the past two days, and apologised to the passengers for the inconvenience.

The challenges include "minor technology glitches, schedule changes linked to the winter season, adverse weather conditions, increased congestion in the aviation system and the implementation of updated crew rostering rules (Flight Duty Time Limitations) had a negative compounding impact on our operations in a way that was not feasible to be anticipated," an airline spokesperson said in a statement.

The sources said over 100 IndiGo flights were cancelled at various airports, including Delhi, Bangalore, Mumbai and Hyderabad. At least 42 flights were cancelled at the Bangalore airport, 38 flights at the Delhi airport, 33 at the Mumbai airport and 19 at the Hyderabad airport, they added.

Besides, scores of flights were delayed.

"IndiGo has been facing acute crew shortage since the implementation of the second phase of the FDTL (Flight Duty Time Limitations) norms, leading to cancellations and huge delays in its operations across the airports," a source told PTI.

"The situation turned bad on Tuesday for the airline and the shortage turned worse on Wednesday with scores of flights cancelled and delayed from across airports in the country," the source said, adding that there are crew rostering as well as baggage system issues.

Social media was flooded with videos showing frustrated passengers arguing with airline staff over the flight cancellations.

IndiGo, which is known for its punctuality, recorded an On Time Performance (OTP) score of 35 per cent on December 2, according to the latest official data.

Citing recent operational performance information provided by IndiGo, DGCA said a total of 1,232 flights were cancelled in November, including 755 flights due to crew and FDTL (Flight Duty Time Limitations) constraints.

As many as 258 flights were cancelled due to "airport/airspace restrictions", 92 flights were cancelled due to the ATC (Air Traffic Control) system failure and 127 flights on account of other reasons, the statement said.

The latest FDTL norms, which entail increased weekly rest periods to 48 hours, extension of night hours, and limiting the number of night landings to only two, as against six earlier, were initially opposed by the domestic airlines, including IndiGo and Tata Group-owned Air India.

But they were subsequently rolled out by the DGCA following the Delhi High Court's directives, albeit after a delay of over one year and in a phased manner and with certain variations to airlines like IndiGo and Air India.

While the first phase of these FDTL norms came into force from July, the second phase, which restricted the night landing to two from six earlier, was implemented from November 1.

The norms were originally to be put in place from March 2024, but airlines, including IndiGo, sought a step-by-step implementation, citing additional crew requirements.

On Wednesday, IndiGo said it has initiated calibrated adjustments to the schedules to contain the disruption and restore stability. The airline did not share any specific numbers.

These measures will remain in place for the next 48 hours and will allow the airline to normalise operations and progressively recover punctuality across the network, it said.

Many passengers took to social media to complain about flight cancellations and delays.

"Deeply unfortunate to see #Ayyappadevotees forced to protest at Hyderabad Airport after @IndiGo6E failed to address hours-long delays. Passengers deserve clarity, and responsible service. Hope the authorities take immediate action," an individual said in a post on X, tagging Prime Minister Narendra Modi, Home Minister Amit Shah and Civil Aviation Minister K Rammohan Naidu.

In the statement, IndiGo said its teams are working around the clock to ease customer discomfort and ensure operations stabilise as quickly as possible. "Furthermore, the affected customers are being offered alternate travel arrangements to reach their destinations or refunds, as applicable".

Airline Pilots' Association of India (ALPA) on Wednesday said the operational disruptions at IndiGo due to crew issues point to a failure of proactive resource planning by dominant airlines, and claimed that there could also be an effort to pressurise regulator DGCA to dilute the new flight duty time limitation norms.

As on December 2, IndiGo had a total of 416 planes in the fleet, with 366 of them in operations and 50 on ground, up from 47 last month, as per the aircraft fleet tracking website Planespotter.com. PTI IAS GDK GMS RAM HVA