India’s aviation regulator on Saturday fined IndiGo a record $2.45 million, issued warnings to senior executives and directed the airline to remove the head of its operations control from his duties after mass flight cancellations last month.

India’s largest airline scrapped about 4,500 flights in the first weeks of December, stranding tens of thousands of passengers nationwide and highlighting concerns over limited competition in the world’s fastest-growing aviation market.

The airline has acknowledged that poor pilot roster planning was the main cause of the disruption. A probe by the Directorate General of Civil Aviation (DGCA) found several deficiencies at the airline after stricter pilot rest and duty rules came into effect last year, the regulator said in a statement.

IndiGo, which holds 65% of India’s domestic market, failed to properly identify planning gaps or maintain adequate operational buffers, the DGCA said, adding that the airline had an “overriding focus” on maximising the use of crew, aircraft, and network resources.

“(IndiGo’s) approach compromised roster integrity and adversely impacted operational resilience,” the DGCA said.

A government source said that the fine was the largest imposed by the authority to date, though it amounted to just 0.31% of IndiGo’s annual profit for fiscal 2024/25.

IndiGo said in a statement that its board and management were “committed to taking full cognisance of the orders and will, in a thoughtful and timely manner, take appropriate measures.”

The DGCA issued warnings to several senior executives, including Chief Operating Officer Isidre Porqueras and Jason Herter, senior vice president of the operations control centre. It directed IndiGo to relieve Herter of his operational duties.

CEO Pieter Elbers received a “caution” for “inadequate overall oversight of flight operations and crisis management,” the regulator said.

IndiGo was also ordered to provide a bank guarantee of $5.51 million in favour of the DGCA to ensure “compliance with the directives and long-term systemic correction.”

The DGCA said the aviation ministry had also ordered an internal inquiry into the regulator’s own functioning.

The cancellations prompted the government to temporarily relax some rules on night duties for pilots to help stabilise IndiGo’s operations, a move criticised by pilot unions and safety advocates.

India’s competition regulator is reviewing allegations of antitrust violations by the two-decade-old airline.