The cause of the sudden change in altitude aboard QF72 from Singapore to Perth, which lead to an emergency landing, remains under investigation.

The Chief Executive Officer of Qantas, Mr Geoff Dixon, said Qantas was assisting the Australian Transport Safety Bureau (ATSB) in its formal investigation.

Mr Dixon said the aircraft's flight data and cockpit voice recorders had been removed and would undergo assessment.

"As always we will cooperate fully with the ATSB, as well as conducting our own investigation into the incident.

"Our primary concern remains the welfare of our passengers and crew on board the flight, and we are focused on doing everything possible to assist them," Mr Dixon said.

He said that passenger and crew information available to date indicated that:

• injuries ranged from abrasions and contusions to fractures;
• the condition of 14 of those on board was considered serious, requiring medical evacuation to Perth by the Royal Flying Doctor Service, although none of the injuries was life threatening;
• up to 30 additional people required attendance at hospital in Perth;
• up to 30 further passengers and crew required first aid treatment for minor conditions;
• all passengers requiring travel to Perth had been accommodated on two special flights arranged by Qantas yesterday evening; and
• the majority of passengers on board was Australian (131), followed by British (53), Indian (40) and Singaporean (38).

"We are grateful for the assistance of the Royal Flying Doctor Service and Skywest who came to the assistance of our passengers and crew in this remote location.

"We would also like to acknowledge the offers of assistance that we received from CareFlight, Woodside Energy, the RAAF and others in the area."

Mr Dixon said information available on the flight at this stage included:

• the incident occurred 80 miles north of Learmonth, which is a joint user airforce base;
• the incident occurred at a cruising altitude of 37,000 feet;
• the aircraft climbed approximately 300 feet before the nose dropped momentarily; and
• the flight crew declared an emergency and diverted to Learmonth, which was the closest suitable diversion airfield.

He said the A330-300 aircraft remained in Learmonth where the ATSB and Qantas were conducting investigations and assessments.

Mr Dixon said Qantas would be contacting every person on board the flight to ensure continued assistance was offered to all passengers and crew.

"We commend the professionalism of our crew, who ensured the aircraft landed safely in Learmonth."