Sydney, Jan 3 (DPA) The autopilot on a Qantas Airways Airbus A330 suddenly disconnected 500 kilometres after taking off from Perth in Western Australia last week, a news report revealed Saturday.The plane was forced to return to Perth, ABC Radio reported.

The incident on Dec 27 was the second midair emergency affecting a Qantas Airbus. Seventy passengers were injured - some of them seriously - in October when a plane suddenly lost altitude during a flight to Singapore and was forced to make an emergency landing at Exmouth.

The Australian Transport Safety Bureau (ATSB) said that because of their similarities the two incidents will be the subject of a joint investigation, ABC reported. It plans to release an interim report about mid-February.