MUMBAI/NEW DELHI, Dec. 9 -- In a rare regulatory intervention, the Directorate General of Civil Aviation (DGCA) is rolling back IndiGo's expanded winter schedule, cutting 5% of the daily departures it had approved and handing those slots to rival airlines.

In a Tuesday order, the DGCA asked IndiGo to revise its winter schedule and curtail the number of flights by 5%, including on high-frequency, high-demand routes. The airline has to submit its revised flight plans by 5 pm Wednesday (10 December).

"The airline has not demonstrated an ability to operate these schedules efficiently (15014 weekly departures for winter schedule)," the regulator noted. "Therefore, it is directed to reduce the schedule by 5% across sectors, especially on high...