Pilots flying the IndiGo's Chennai-Kuwait flight declared emergency in the early hours of Friday and landed back at the Chennai airport soon after the departure due to a fire alarm, which later turned out to be false, said a source.
The A320neo plane had taken off around 1.20 am with more than 160 passengers.
Just 15 minutes after the departure, the pilots observed a fire alarm and immediately relayed the emergency code 7700 to all Air Traffic Controls, said a source privy to the development.
The fire alarm was later found to be because of faulty smoke detectors in cargo compartment, the source said.
A spokesperson of the airline said, "IndiGo A320 was operating Chennai-Kuwait 6E-1751. After take-off from Chennai, the pilot observed a momentary message of the smoke detector in the aft cargo compartment."
"As a precaution, the pilot returned to Chennai. After arrival it was confirmed that the message was false. The aircraft will be back in operations shortly. Alternate arrangements for all the passengers were made," the spokesperson added.