India, Dec. 5 -- While all airlines must comply with the new crew rest and fatigue-management norms, no carrier has been impacted as severely asIndiGo, India's largest airline by a wide margin.

The carrier's on-time performance plunged below 20 percent this week, and more than 1,200 flights have been cancelled over the past two weeks, prompting intervention from the Directorate General of Civil Aviation (DGCA).

The revised FDTL rules, introduced by the DGCA to reduce pilot fatigue and align India with global safety practices, significantly expand weekly rest requirements and restrict night operations.

Pilots must now receive 48 consecutive hours of weekly rest instead of 36; night hours have been redefined as midnight to 6 am instead o...