An Air India flight headed for Mumbai from Dubai overshot its destination and was halfway to Goa before its dozing pilots were woken out of a deep slumber by air traffic control, a report said.
The high altitude nap took place approximately two weeks ago, the Times of India reported Thursday.
Some 100 passengers were on board the state-run flight that originated from Dubai and flew to the western Indian city of Jaipur before heading south to Mumbai when both pilots fell asleep, a source told the paper.
"After operating an overnight flight, fatigue levels peak -- and so the pilots dozed off after taking off from Jaipur," the source, who was not identified in the report, said.
The plane flew to Mumbai on autopilot, but when air traffic there tried to help the aircraft land, the plane ignored their instructions and carried on at full speed towards Goa.
"The aircraft should have begun its descent about 100 miles (160 kilometers) from Mumbai, but here it was still at cruising altitude. We checked for hijack," the source said.
Finally air traffic control buzzed the cockpit and woke up the pilots, who turned the plane around, the report said.
When contacted by the newspaper, Air India said it was gathering information on the incident.
The manager of Mumbai's airport insisted the aircraft had suffered a "communications failure" and that no napping had taken place.
But sources told the daily that authorities were trying to hush up the matter.
Indian papers reported this week that a flight operated by private airline Jetlite to the central Indian city of Patna was grounded after the pilot was found to be drunk.
Around 50 pilots are grounded each year because they had consumed alcohol before taking a flight, according to India's civil aviation authorities.
The Director General of Civil Aviation (DGCA), a body controlling airline operations in India, said dozens of pilots are found to have consumed alcohol during routine pre-medical tests every year.
India is one of the fastest growing aviation markets in the world with dozens of new airlines competing with each other everyday, often resulting in pilots forced to fly at short notices.
The country has about 4,500-5,000 commercial pilots, and another 2,500 are undergoing training.
Civil aviation rules specify that pilots and cabin crew cannot consume alcohol 12 hours before taking a flight.