Mystery Messages Caused Qantas Plunge

Mystery Messages Caused Qantas Plunge

www.news.com.au

AIR investigators have confirmed a series of electrical messages was to blame for a Qantas plane plunging more than 650ft and injuring 44 passengers.

A preliminary report by the Australian Transport Safety Bureau said the aircraft's black box – known as the air data inertial reference system (ADIRU) – produced spurious message signals causing the aircraft to dive suddenly.

(visit the link for the full news article)

Scary.

I didn't even know the black box could affect the actual operation of aircraft.

Passenger laptops and mobile phones were believed to have interfered with the flight system.

Investigators also considered an external interference, possibly by signals from the Navy's Harold E Holt submarine's communications base.

Interference from laptops and mobile phones or from a military communications centre?

If this plane had gone down, I wonder what would have been blamed?




www.news.com.au
(visit the link for the full news article)

The ADIRU has nothing to do with the 'black box'. The ADIRU, sent faulty 'messages', or signals, to the autopilot or fly-by-wire system, which caused the plane to drop. I don't see an external force like laptops or phones interfering because the ADIRU is an INERTIAL REFERANCE UNIT. key word, INERTIAL. For altitude, & pitch information, it relies on sensors physically wired to it. A phone interfering with it is akin to a phone interfering with your calculator. Not going to happen. Therefore, I'm going with a fault with the unit itself, the software, or something that feeds data to the ADIRU, such as an accelerometer, like on Malaysia Airlines Flight 124.

en.wikipedia.org...

[edit on 13/11/2008 by C0bzz]

Originally posted by C0bzz
The ADIRU has nothing to do with the 'black box'. The ADIRU, sent faulty 'messages', or signals, to the autopilot or fly-by-wire system, which caused the plane to drop. I don't see an external force like laptops or phones interfering because the ADIRU is an INERTIAL REFERANCE UNIT.

[edit on 13/11/2008 by C0bzz]

Thanks for clearing that up. That's what I get for still thinking journalists know what they are talking about.

yeah..your thinking of the 'black box' used in recording flight data or cockpit voice/data. All kinds of 'black box's' on planes.

Sounds like another fly-by-wire mishap for Airbus. This was a A330, I'm pretty sure all their planes are this way.

I don't buy the interference from personal electrical devices either, that's just a way for them escape liability.

In any case, another reason to leave your seat belt on after the pilot has turned off the seat belt sign. I feel bad for all the people that were hurt. At least they were able to make a safe landing after.

I do believe GSM phones can interfere with just about anything. Not saying that it is the case here and it's not likely, however anything using a linear amplifier could certainly be affected by GSM.

Try this:
Get a ghetto blaster and turn the volume to a whisper.
Place your GSM phone on top of it.
Leave it there and wait or call your own cell from a land line and listen to the polling tones.
They will be remarkably louder than the broadcast you had turned down to a whisper and possibly as loud as the stereo can possibly go, bypassing the preamplifier altogether or causing the preamp to max out. Notice the shift in the volume from when the GSM phone is pinged by the cell or vice versa.

Now if the plane's autopilot box is using inertia for feedback etc, usually there will have to be sensors in every section of the craft, front to back & from wingtip to wingtip. Those sensors would more than likely have to be amplified to make the trip back to the "brain" of the craft or to even register without attenuating first. This is a linear amplifier circuit in principle, just that the signal isn't audio.

Not likely in this case or any really, but it should never be discounted as a possibility. The GSM system is amazing yet old and VERY disruptive technology. There is definitely a reason why in the past they used to ask that all electronic devices are turned off when taking off and landing. I always wondered why allow them when autopilot is engaged?



[edit on 13-11-2008 by Atlantican]

...... what if aliens/ufo's which ever are testing our 'flying craft'

I mean, Qantas never had an issue before, last few months they've had dozens.

the drop the other week, and this are both very unusual events..

just a thought..

How they did not already simulate this kind of accident before (mostly every passenger have a cellular on him) ?

When you know the crazy level of "security" around commercial flights today, it seems very strange they ask you to take off your shoes (to see if you do not hide matches lol) and not to secure your phone to be sure you wouldn't use it on board

reply to post by C0bzz


reply to post by toepick


Both C0bzz and toepick said it well. Most likely cause is fault with the unit or system itself. There is a high probability that any other explanation is indeed to ward off claims of liability. Though the military com system theory is interesting. However all units are encased in metal shielding, mini Faraday cages which act to cancel out most interference and external noise.

I repair 'black boxes' (flight data recorders) and see plenty of units with various failures. Airplanes vibrate and undergo plenty of other stress. So does the equipment on board, and even with the rigorous standards used in flight system electronics, sometimes circuits can fail. Intermittent failure is very common as a single solder connection can crack or expand and contract with heat/vibration/etc. With flight data recorders it isn't as threatening. However with a control system or related peripheral such as what is mentioned in the article, even an intermittent failure can turn catastrophic if it happens in the right system. It is why helicopters are said to be the most dangerous aircraft, because of the added amount of control systems on board that could fail.

Some trivial information for everyone: Most of the 'black boxes' I see are far from black, but are instead painted usually bright orange. Though there are many that are indeed flat black.

Originally posted by 1energy
How they did not already simulate this kind of accident before (mostly every passenger have a cellular on him) ?

When you know the crazy level of "security" around commercial flights today, it seems very strange they ask you to take off your shoes (to see if you do not hide matches lol) and not to secure your phone to be sure you wouldn't use it on board

That's next on the list of things you can't have on a plane.

PLANES would fall out of the sky regularly if the signals from Western Australia's Harold E. Holt Naval Communications Base posed any threat to them, the base's manager said yesterday.

Russell Levien said his initial inquiries suggested it was "highly unlikely" that the naval base at Exmouth played any role in the sudden plunge of a Qantas jet last month in which 70 people were injured, 14 of them seriously.

A preliminary report into the incident, released yesterday by the Australian Transport Safety Bureau, said it would investigate the possibility that transmissions from the base interfered with aircraft systems.

Air safety experts are also searching for a hardware or software fault that may explain why the Airbus A330-300 made a roller-coaster ride on October 7.

Experts at manufacturer Northrop Grumman's US facilities will on Monday begin tests on a component blamed for sending faulty data to flight control computers and causing the Airbus to twice pitch downwards. The incident occurred about 160km from the naval base, which emits very low frequency signals to communicate with Australian and US submarines in the region.

"We'd have planes down all around us if it was us (who caused the problem)," Mr Levien told The Weekend Australian, referring to the fact that planes regularly fly near the base. As the base manager, Mr Levien said he had reviewed the transmissions on the day of the accident and did not notice anything unusual. He had also contacted similar naval communication bases around the world, including the US naval station at Cutler, in the US state of Maine -- which is under a flightpath -- and none was aware of any interference with aircraft.


www.theaustralian.news.com.au...

The Australian Transport Safety Bureau said it believed a faulty component, called the air data inertial reference unit (ADIRU), caused the problem by feeding "erroneous and spike values'' about the angle at which the plane was flying to a flight control computer.

"This led to several consequences, including false stall and over speed warnings,'' and later 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.

After the inciden they found one of the three Air Data Inertial Reference Unit (ADIRU) was defective and it sent to the US base of its manufacturer, Northrop Grumman for to find out what led to the (fault) and reduce the chance of that happening in the future.

"This is now clearly a manufacturer's issue and we will comply with the manufacturer's advice," she said.

Airbus issued a bulletin to all operators of its planes containing the component, with advice on how to reduce the risk of a crash in the event of such a malfunction.

The aim of the bulletin is to:

update operators on the factors identified to date that led to the accident involving QF72,provide operational recommendations to mitigate risk in the event of a reoccurrence of the situation which occurred on QF72. In order to "minimize risk in the unlikely event of a similar occurrence" … an Operational Engineering Bulletin is on its way … Is it simply to emphasize the already published procedure or is it something new the QF72 crew could not have known before ?

www.eturbonews.com...

> The A/C was flying at FL 370 with Autopilot and Auto thrust system engaged
> without any reported or recorded anomaly, when the IRS 1 Fault has been
> triggered and the Autopilot automatically disconnected.
>
> From this moment, the crew flew manually the aircraft to the end of the
> flight except for a short duration of few seconds.
>
> From the time the IRS 1 Fault has been triggered, the recorded
> parameters of the ADR part of ADIRU 1 include erroneous and temporary
> wrong values in a random manner. These values are spike values and not
> sustained values. ADIRUs 2 and 3 seemed to have operated normally.
>
> This abnormal behaviour of the ADIRU 1 led to several consequences as
> follows:
> - unjustified stall & overspeed warning
> - loss of attitude information on Captain Primary Flight Display
> (PFD).
> - several ECAM system warnings.
>
> About 2 minutes after the initial IRS Fault, the ADIRU spikes generated
> very high, random and temporary values of the angle of attack leading to:
> 1/ the flight control laws commanding nose-down aircraft movements (A/C
> pitch attitude decreased from 2° nose-up to 8° nose-down and vertical load
> factor changed from 1g to -0,8g.
> 2/ the Flight Control Primary Computer (FCPC) "F/CTL PRIM 1 PITCH
> FAULT" ECAM WARNING was triggered


> The DFDR data show that the ADR 1 continued to generate random spikes.
>
> A second nose-down aircraft movement was encountered later on, but with
> less important effects in terms of aircraft trajectory. It also led to
> generate the "F/CTL PRIM 2 PITCH FAULT" ECAM WARNING. This, combined with
> the previous "F/CTL PRIM 1 PITCH FAULT" ECAM WARNING led to switch from
> NORMAL to ALTERNATE law.

>
> The type of ADIRU, which is involved, is NORTHROP GRUMMANN (previously
> LITTON), PN 465020-0303-0316.
>
> 3. OPERATIONAL RECOMMENDATIONS for A330/A340 fitted with NORTHROP
> GRUMMANN - LITTON ADIRU
>
> Pending final resolution, Airbus will issue an OEB 74-1 that will
> instruct the crew to select OFF the whole ADIRU in case of IR failure,
> instead of switching OFF only the IR part.

www.atsb.gov.au...

reply to post by Atlantican


Sensors in the aircraft are probably connected with ARINC 429. It defines the physical and electrical interfaces of a two-wire data bus and a data protocol to support an aircraft's avionics local area network.

ARINC 429 is a two-wire, point-to-point data bus that is
application-specific for commercial and transport
aircraft.

www.actel.com...

The prohibition on the use of certain electronic devices in-flight on commercial aircraft has become a controversial issue, as, although usually justified as a safety requirement to prevent interference with aircraft avionics, it is criticized by those that argue that cell phones, WiFi, Bluetooth, and other digital radio systems are incapable of interfering with such robust protocols as ARINC.

ARINC 429 employs several physical, electrical, and protocol techniques to minimize radio and electrical interference from on-board radios and from other transmission cables.

It's cabling is a shielded 78Ω twisted-pair[4]. ARINC signalling defines a 15V differential between the Data A and Data B levels within the biphase transmission (i.e. 5V on Data A and -10V on Data B would constitute a valid driving signal), and the specification defines acceptable voltage rise and fall times.

ARINC 429's data encoding uses a complementary differential bipolar return-to-zero (RZ) transmission waveform, further reducing EMI emissions from the cable itself.

en.wikipedia.org...

I don't really pay attention to mobile phones rules, because I don't really care. However, if I'm not mistaken, mobile phones are supposed to be off or in flight mode inside aircraft. If the rule only applies when low, then that is possibly because navigation may not be by robust inertial nav updated with computers, but by a single RF source, such as ILS.

As for mobiles being blamed, them claiming this to excape liability - rediculous. No-body, but the media stated anything like that. If they did, it would give them more liability, not less, as it would prove there planes were prone to interferance.

[edit on 18/11/2008 by C0bzz]

Originally posted by C0bzz
As for mobiles being blamed, them claiming this to excape liability - rediculous. No-body, but the media stated anything like that. If they did, it would give them more liability, not less, as it would prove there planes were prone to interferance.

Excellent point.

It is pretty obvious that this was a unit/system malfunction entirely unrelated to anything but a standard operational failure, intermittent in this case. The manufacturing engineers will run it through their standard tests, find a faulty component or solder connection, fix it, and it will be back in service. Though there may be some protocol disallowing a unit whose failure caused some sort of injury to be put back in service after repair, even if it is 100% repaired. Not sure on those rules.

UPDATE: IT'S HAPPENED AGAIN!

A MALFUNCTION has forced a Qantas jet to return to Perth, prompting concerns for the second time in three months that interference from a defence station in northwestern Australia may be to blame for a mid-air drama on the national carrier.

Qantas flight 71 was on route to Singapore with 277 passengers about 8.30am last Saturday when it had to return to Perth after the jet's autopilot disconnected because of a problem with a unit that supplies key information to flight control computers.

The Airbus A330-300 was 45 minutes into the journey and about 380 nautical miles south of the Harold E. Holt Naval Communications Station - 15km north of Exmouth - when the autopilot switched off, The Australian reports.

LINK

And there is still speculation that the Comms Station is to blame.