more detail below with direct quotes from ATSB
By Ray Brindal
Of DOW JONES NEWSWIRES
CANBERRA (Dow Jones)--A Qantas Airways Ltd. (QAN.AU) plane involved in a midair
incident over Western Australia state experienced an irregularity in its onboard computer
equipment that left the plane flying "of its own accord", an aviation safety
official said Wednesday.
Qantas, Australia's largest carrier, has reported about 40 people sustained
injuries Tuesday on board the Airbus A330-300 flight to Perth from Singapore.
Julian Walsh, director of aviation safety at the Australian Transport Safety Bureau,
said an on-board electronic centralized aircraft monitoring system indicated there was
"some irregularity with the elevator control system" of the aircraft.
The aircraft departed its normal flight at 37,000 feet, climbed 300 feet, "then as
the crew were responding, the aircraft pitched down quite suddenly and rapidly," he
said.
"Certainly, there was a period of time when the aircraft performed of its own
accord," Walsh said.
The crew declared an early stage "pan pan" alert almost straight away, then
around 3-4 minutes later they upgraded that to a "mayday" alert, which
indicates an urgent situation with a need for absolute priority, he said.
The aircraft, built in 2003 and operated by Qantas since, made an emergency landing
about 1.30 p.m. local time, at a remote airfield at Learmonth, an Australian defense
force bare air base, near Exmouth, in Western Australia state, 1100 kilometers northeast
of Perth.
Walsh said the alert upgrade could have occurred after the crew assessed the injuries
to passengers at the back of the aircraft and the importance of diverting the flight.
"Whether the pilots were in complete control of the aircraft or not is a very hard
thing for me to say at this early time. Obviously, until we get the flight data recorder
and the coughpit voice recorder and we can actually look at the history of the flight, we
won't really understand exactly what has happened during the event," he said.
Qantas, which is known as one of the world's safest airlines, has suffered a
string of mechanical incidents in recent months, with air safety investigators announcing
in August a review of the carrier after other incidents.
Walsh said he didn't want to rule anything in or out in terms of the cause of this
latest incident.
While the crew referred to some "flight control computer issues," it is
important to look at the environmental conditions as well, as often these things can
interact, he said.
The bureau will look at all aspects of the operation of the aircraft including its
maintenance history to identify what could have led to this incident, he said.