Official: gadgets not responsible for Qantas jet plunge
Aussie Transport Safety Bureau lets laptops off the hook
Initial investigations into the Qantas Airbus A330 mishap have concluded that it was due to incorrect information fed into the flight control system and not interference from passengers' gagdets.
A report by ABC news states that the Australian Transport Safety Bureau (ATSB) said incorrect information from a faulty air data inertial reference system (ADIRS) triggered a series of alarms and then prompted the Airbus A330-300's flight control computers to put the jet into a 197m nosedive.
The plane was cruising at an altitude of 37,000 feet when a fault in the ADIRS - not interference from passenger electronics, as Qantas had first suggested - caused the autopilot to disengage.
"About two minutes after the initial fault, the [ADIRS] generated very high, random and incorrect values for the aircraft's angle of attack," the ATSB said in a statement.
"These very high, random and incorrect values of the angle attack led to the flight control computers commanding a nose-down aircraft movement, which resulted in the aircraft pitching down to a maximum of about 8.5 degrees."
The pilots quickly regained control of the Airbus A330-300, issued a mayday call and successfully completed an emergency landing at Learmonth air force base in remote Western Australia. A number of passengers received medical treatment.
"The crew's timely response led to the recovery of the aircraft trajectory within seconds," the ATSB said.
The Herald Sun recently revealed that Qantas and other airlines were warned in July 2004 and again in August 2007 about the potential for a serious malfunction aboard the A330-300 series aircraft. Problems with elevation controls, including concerns about potential break-down of hydraulic "O-ring" seals were highlighted by Australia's Civil Aviation Safety Authority.
Reminds me of...
Why does this remind me of "What do you mean kilometers, we thought it was miles," and the ever infamous "Unsigned Values? No, we always passed _SIGNED_ values. Why would you assume otherwise."
One of the funny, and scariest presentation I ever went to was at an Embedded System Conference a few years back. The presenter was talking about failures that should have been caught, but weren't, and the results of them in some safety critical systems. (One was a radiation therapy machine, one was a mars probe, several were missiles.)
resp to Kevin
"If the system was getting two sets of information that were at odds with each other, then disconnecting autopilot _might_ be a sensible thing to do. You know _something_ is wrong but not _what_ is wrong."
No, the safest thing to do would be to do nothing, to simply have ignored the input and carry on just as before.
Why? Think about it. The auto-pilot was engaged and the aircraft was in a safe situation, probably flying straight and level. Errant input appears, ignore the new inputs, you know something is wrong, but not what, sound an alarm to get the attention of the pilot, issue a voice warning to state the problem and suggest disengaging the auto-pilot.
If the system disengages the auto-pilot automatically, the flight control system will read the demand inputs from the flight controls, stick, throttle lever, which can be in any position, the flight control system will regard these inputs as being genunine inputs from the pilot, which they are not.
I would argue it is safer not to disengage the autopilot, having said that, if the state of the aircraft when the autopilot was engaged was losing height and then the errant input from the AIDRS occurred, you might decide that leaving the auto-pilot engaged might be an unsafe situation ( depends how high you are and how high the mountains are!), but you're still at risk of the flight controls being in a non-suitable state and the flight control system taking those inputs and moving the control surfaces to achieve what it thinks is demanded input by the pilot.
RE: ..but flight computers probably were
"... an A330 carries THREE of these and only one was faulty."
WHERE'S MY MINORITY REPORT?!
Did you say 'overlords'?
You meant 'protectors'...
The latest thinking is
that high powered transmissions from a nearby naval base may have been responsible.