It is alleged that the pair only returned 40 minutes later when the auto-pilot button was accidentally switched off.
The incident happened at 33,000 feet during a flight from Bangkok to Delhi last month. Both the pilot and his co-pilot have denied the claims.
They say the hostesses were in the cockpit for longer then the time permitted and that it was the co-pilot who accidently switched off the auto-pilot.
Air India says its investigation rejected the claim that the pilots were asleep on the job. The airline says it only took disciplinary action because the hostesses were in the cockpit for longer than allowed.
“It is categorically stated that at no point of time the cockpit was left unattended by the cockpit crew,” Air India said. “As the inquiry confirmed the overstay of the cabin crew in the cockpit, administrative action was taken against them and the pilot.
“They have been suspended pending the final inquiry of the incident,” the airline added.