Pesky computer....

Computer sent Qantas jet into dive: Investigators
Source: www.smh.com.au
Date: 14 October 2008

A computer fault caused the autopilot system to be overridden, sending a Qantas plane into a mid-air plunge over Western Australia last week, authorities said tonight.

The air data computer - or inertial reference system - for the Airbus A330-300 sent erroneous information to the flight control computer causing the autopilot to disconnect, the Australian Transport Safety Bureau (ATSB) said.

More than 70 people on Qantas flight QF72 from Singapore to Perth were injured last Tuesday when the Airbus, carrying 303 passengers and 10 crew, suddenly dropped altitude.

People were hurled around the cabin and the pilot was forced to make an emergency landing in Western Australia's north.

Australian Transport Safety Bureau investigation director Julian Walsh said the faulty unit continued to feed "erroneous and spike values'' to its primary computers.

"This led to several consequences, including false stall and overspeed warnings,'' he said.

"About two minutes after the initial fault (the air data inertial reference system) generated very high and incorrect values for the aircraft's angle of attack.''

This led to the flight control computers commanding the aircraft to pitch down, Mr Walsh said.

"The crew's timely response led to the recovery of the aircraft's trajectory within seconds, and during the recovery, the maximum altitude lost was 650 feet.''

Mr Walsh said analysis of the digital flight recorder showed the faulty air data system continued to generate false information, leading to a second, less serious "nose down aircraft movement''.

The ATSB is expected to provide a preliminary factual report within three weeks.

There had been suggestions the incident may lead to the grounding of Airbus A330-300 models.

Mr Walsh today said that would be a matter for regulatory authorities.

"However, the information we have at hand indicates that this is a fairly unique event,'' he said.

"These aircraft have been operating over many hundreds of thousands of hours over many years, and this type of event has not been seen before.''

"It's probably unlikely there will be a recurrence, but obviously we won't dismiss that, and it's important that we investigate to find out what led to the (fault) and reduce the chance of that happening in the future.''

Mr Walsh said Airbus had provided advice to airlines operating the A330-300 that would minimise risk in the very unlikely event of a similar incident occurring again.

All I can say about this event is to keep your seatbelt on at all times, as those who did not have their belt on were the one's who were injured. It's compulsory in a car and I believe it should also be onboard aircraft.