At least 250 IndiGo flights were cancelled on Thursday as turmoil persisted at key airports across India, with the carrier struggling to adjust to tough new crew rostering standards. The airline declared on Wednesday that it has started making "calibrated adjustments" to its plans for the following 48 hours and cancelled at least 150 flights.
According to data from the civil aviation ministry, the on-time performance (OTP) of India's biggest airline, IndiGo, fell to 19.7% on Wednesday from 35% the day before.
33 flights from Delhi, 68 from Hyderabad, 85 from Mumbai, and 73 from Bengaluru were canceled on Thursday, according to an official with knowledge of the situation.

At least 67 flights—37 departures and 30 arrivals at Delhi airport, 42 at Bengaluru, 40 at Hyderabad (19 departures and 21 arrivals), and 33 at Mumbai (17 departures and 16 arrivals)—were cancelled on Wednesday.
Calibrated changes will be in place for the next 48 hours, according to a statement released by IndiGo on Wednesday. This will normalize operations and gradually restore network timeliness. "Our teams are working nonstop to minimize customer discomfort and guarantee that operations stabilize as soon as possible." The airline said the impacted clients are being offered alternate travel arrangements to reach their destinations or refunds, where applicable.

The airline did not offer an update on its flying operations on Thursday.
The turmoil was caused by a number of factors, including bad weather, increased traffic, and the installation of modified Flight Duty Time Limitations (FDTL), which went into effect in November.
An emergency Airbus A320 software patch rushed through over the weekend of November 29-30 interrupted crew scheduling precisely when the airline was operating with low slack due to the FDTL requirements.
The Directorate General of Civil Aviation (DGCA) data showed the airline had been under duress, having cancelled 1,232 flights in November—755 of them related to FDTL issues—with OTP sliding to 67.70% from 84.1% in October.

The airline mayhem was exacerbated on Wednesday by issues with IndiGo's luggage systems at Delhi's Terminals 1 and 3.
Flights were halted when passengers turned up to check in. Many claimed to have lost out on future opportunities.
On July 1 and November 1, new FDTL regulations were put into effect in two stages. The guidelines have been devised to reduce weariness and boost rest intervals. They made it mandatory to extend night hours, raise weekly rest intervals to 48 hours, and reduce the number of night landings from six to two.

The DGCA said on Wednesday it was investigating the situation and had invited IndiGo to its headquarters “to present the facts leading to the current situation along with plans to mitigate the ongoing delays and cancellations”.
Every day, the airline conducts between 2,200 and 2,300 flights to more than 90 domestic and 45 overseas locations.
According to the aircraft fleet tracking website Planespotter.net, as of December 2, IndiGo has 416 aircraft in total—366 in service and 50 on the ground—up from 47 the month before.
The Airline Pilots Association of India, which represents over 800 pilots, on Wednesday blasted what it called “a failure of proactive resource planning” by prominent airlines.

IndiGo's OTP of only 35% on Tuesday was the lowest of all Indian carriers and a sharp decline from its usual performance of at least 80% at major airports.

Ameya Joshi, an aviation analyst and former network planner, said IndiGo is not just the largest carrier but also has major flights throughout the evening, which now demand more rest.