New Delhi, Dec. 3 -- India's aviation regulator is investigating how Air India operated an aircraft for two days in November without a valid Airworthiness Review Certificate (ARC), a document that ensures compliance with safety standards.

The regulator did not name the aircraft type but referenced the registration code of an Airbus A320 (VT TQN), implying that it was a single-aisle (narrow body) jet. Air India, admitting the lapse, ordered an internal inquiry into the matter and suspended eight staffers.

Mint breaks down the process of getting airworthiness certificates, how the slip-up may have happened, and what's next for the airline as the regulator investigates the matter.

Airworthiness certificates validate the safety of aircraft...