Two pilots of a British passenger flight fell asleep, leaving it on autopilot.
The two pilots, who were in charge of the 325-seat passenger long-haul flight, admitted their actions shortly after take-off in an Airbus A330 operated by a British-based airline on 13 August.
The UK Civil Aviation Authority (CAA) revealed that the pilot and co-pilot had agreed to take turn having short naps, news.com.au reports.
However, one of them woke up to discover that they had both been asleep at the same time and did not know how long the plane had been unsupervised.
The pilots voluntarily reported their mistake to the CAA, which has hidden the name of the airline.
The CAA's report said the flight crew was suffering from symptoms of 'severe fatigue'.
A spokesman for the CAA said it would be 'very surprised' if any disciplinary action was taken against the pilots, the report added.
