This is not really a story about seatbelts! In the full ATSB report, it's a warning about the increasing reliance on automation in large passenger aircraft - in this case the problem of an algorithm which failed to protect the ADIRU from faulty data input. The incident was the third of its kind in 28 million hours of operation in AB330/340 aircraft, but all three occurred off the coast of Western Australia, to Qantas aircraft. Here's the relevant extract of the report, just released:
There was a limitation in the algorithm used by the A330/A340 flight control primary computers for processing angle of attack (AOA) data. This limitation meant that, in a very specific situation, multiple AOA spikes from only one of the three air data inertial reference units could result in a nose-down elevator command. Procedural changes issued by Airbus On 15 October 2008, the aircraft manufacturer issued Operations Engineering Bulletin (OEB) OEB-A330-74-1, which was applicable to all A330 aircraft fitted with Northrop Grumman ADIRUs.201 The OEB stated that, in the event of a NAV IR [1, 2 or 3] FAULT (or an ATT red flag being displayed on either the captain’s or first officer’s primary flight display), the flight crew were required to select the air data reference (ADR) part of the relevant ADIRU OFF and then select the relevant inertial reference (IR) part of the relevant ADIRU OFF. The problem was described as a ‘significant operational issue’ and operators were advised to inform their pilots of the OEB without delay and insert the procedure in the Flight Crew Operations Manual. A compatible temporary revision was issued to the Minimum Master Equipment List at the same time.
The ATSN report is AO-2008-070 and can be found at http://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-070.aspx
At the time of the AF447 there was talk of "similar incidents" at Qantas the year before. Is this the episode to which they were referring? I assumed it was unrelated because after the first few weeks nothing more was reported while AF447 was still in the news.
Well, it's 3 years old. Airbus corrected the problem long before this report, and only 3 times in 28 million hours. Pilots did as they were supposed to and flew the plane, recovering from the upset. what is puzzling and in my mind, bear more investigation. All 3 happened to Qantas aircraft and off the West Coast of Austraila. That's puzzling and seems a little more than coincidence. AB is not the oly company that use NG ADIRU's.Had the pax done what we are all told when we fly, keep the belts on, there probably would not have been as many injuries.
The final report stated that the weather was fine and clear. If you'd like to read the official report: http://www.atsb.gov.au/media/3532398/ao2008070.pdf
When was the last time you watched the safety breifing or looked at the card or the nearest exit? Most people are too busy with I pods and reading material. Keep the belts on.
I always look at the card and look for the nearest exit(s). I also pay attention that the flight attendants have a one-on-one with the people on the exit row. I watch the briefing if the type of plane is one I've not flown before.
I've never flown on a plane where I couldn't see out a window or that had video or movie displayed/available. I don't feel like I've missed out, either. I'm more interested in knowing what's really going on around me. A movie of the view out the cockpit would be fine, though.
I don't know if the original squawk I posted several days ago has been seen, as it doesn't appear on this page. When the first brief newspaper report of the ATSB final report came out, I posted the link to it, and a key extract about the algorithm. There are two important findings buried in the document which has publicly been reported as concentrating on the importance of keeping seat belts fastened. The first is that the algorithm Airbus used to interpret AOA data being fed to the ADIRU failed to cope with unexplained spikes in the data. The algorithm was incompetent (my words) and has been re-written by Airbus. The second important, but problematic point which the ATSB could not resolve, was what caused the spikes. There is no Bermuda Triangle off the coast of Western Australia (anymore than there was in the Atlantic off Florida). But there is a powerful very low-frequency U.S.naval communications station in the area - the Harold Holt facility named after a former prime minister - which is a vital link in U.S. communications with its nuclear submarines in the Indian Ocean. Signals from this station were obviously a suspect, as all three incidents occurred in the same proximity, and all to Qantas aircraft (two to the same aircraft). The ATSB concluded that the signal strengths from Harold Holt, and from a high-frequency communications station at North West Cape were not sufficient to affect the ADIRUs: "The naval communication station transmitted at a very low frequency (VLF) of 19.8 kHz, and the transmission power was about 1 megawatt using an omni-directional antenna. The station was transmitting at the time of the three data- spike occurrences. However, it was considered extremely unlikely that these transmissions had any effect on the ADIRUs."
Although it could not establish a link, no doubt the inconclusive finding will leave the door open to much speculation.
[This comment was deleted.]
There was a limitation in the algorithm used by the A330/A340 flight control primary computers for processing angle of attack (AOA) data. This limitation meant that, in a very specific situation, multiple AOA spikes from only one of the three air data inertial reference units could result in a nose-down elevator command.
Procedural changes issued by Airbus
On 15 October 2008, the aircraft manufacturer issued Operations Engineering Bulletin (OEB) OEB-A330-74-1, which was applicable to all A330 aircraft fitted with Northrop Grumman ADIRUs.201 The OEB stated that, in the event of a NAV IR [1, 2 or 3] FAULT (or an ATT red flag being displayed on either the captain’s or first officer’s primary flight display), the flight crew were required to select the air data reference (ADR) part of the relevant ADIRU OFF and then select the relevant inertial reference (IR) part of the relevant ADIRU OFF. The problem was described as a ‘significant operational issue’ and operators were advised to inform their pilots of the OEB without delay and insert the procedure in the Flight Crew Operations Manual. A compatible temporary revision was issued to the Minimum Master Equipment List at the same time.
The ATSN report is AO-2008-070 and can be found at http://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-070.aspx