India, Dec. 5 -- IndiGo CEO Pieter Elbers issued a public apology on Friday evening after the airline was forced to cancel more than a thousand flights in a single day, calling it the "most severely impacted day" in the carrier's history.

The country's largest airline, which operates around 2,300 domestic and international flights daily, scrapped "more than half" of its schedule.

The crisis has been triggered by new pilot duty regulations that increase weekly rest hours from 36 to 48, while also reducing the number of allowed night landings from six to two per week.

In a detailed message to passengers, Elbers outlined three steps the airline is taking to stabilise operations. First, IndiGo has intensified communication with customers, ...