The revised regulations come months after the watchdog decided to conduct a review of pilot fatigue data collected during spot checks and surveillance of airlines after an IndiGo pilot collapsed and died in August before his flight.

The regulator also cut the maximum flight duty period to 10 hours from 13 hours for pilots working nights and limited the number of flight landings to two, from six, during night operations.

The Directorate General of Civil Aviation's (DGCA) revised regulations, which considered practices in the United States and the European Union, also amended the definition of night duty to cover the first six hours of the day, from five earlier.

The DGCA will mandate all airline operators to submit quarterly fatigue reports and comply with the revised regulations by June 1, 2024.

(Reporting by Kashish Tandon in Bengaluru; Editing by Mrigank Dhaniwala and Savio D'Souza)