AF447
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The aircraft isn't going to be "grounded".
And it doesn't require "politics" to interfere.
Per the guidance material for continuing airworthiness in EASA (ACJ39.3(b)(4) is the latest I have here) the probability of a catastrophic event which would require immediate grounding of an affected fleet is 2X10^-6 i.e. one event in 500,000 flight hours.
The current A330 fleet is approx 600 aircraft. Assuming about 50% untilization (which seems to be about the rate for the accident aircraft since delivery) that would imply the fleet is accruing flight hours at about 200,000 fh/month.
There would therefore have to be an expected accident rate of the order of one per three months to require grounding. Since the historic rate is one per ... well, since service entry, it seems clear that the hazard is not sufficient to require grounding by any reasonable assessment of the figures, unless there is something very specific going on (like a production batch issue, in which case only that batch would be impacted of course)
And it doesn't require "politics" to interfere.
Per the guidance material for continuing airworthiness in EASA (ACJ39.3(b)(4) is the latest I have here) the probability of a catastrophic event which would require immediate grounding of an affected fleet is 2X10^-6 i.e. one event in 500,000 flight hours.
The current A330 fleet is approx 600 aircraft. Assuming about 50% untilization (which seems to be about the rate for the accident aircraft since delivery) that would imply the fleet is accruing flight hours at about 200,000 fh/month.
There would therefore have to be an expected accident rate of the order of one per three months to require grounding. Since the historic rate is one per ... well, since service entry, it seems clear that the hazard is not sufficient to require grounding by any reasonable assessment of the figures, unless there is something very specific going on (like a production batch issue, in which case only that batch would be impacted of course)
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Now lets me realistic Gentleman.
An 330 flying into a horrendous storm and crashing due to potential icing of the Pitot tubes and super freezing ice on other areas of the airframe, (some suggest engine ingestion) caused by flight into CB. Surely this cannot be enough to ground the entire 330 fleet. An AD suggesting caution in CB, I can understand.
The DC 10 was a totally different problem and should not be compared in anyway.
The DC 10 was a totally different problem and should not be compared in anyway.
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June 29, 1994
Boeing mystified over 'violent' 747 stall
Boeing has failed to find the cause of an incident in which a Singapore Airlines (SIA) Boeing 747-400 stalled while at cruising altitude over Bucharest on a Singapore-Heathrow flight (Flight International, 3-9 November, 1993).
Independent reports from two private pilots, who were passengers, subsequently stated that the incident was far more violent than Flight International's report or the SIA statement at the time indicated.
The incident involved cockpit audible stall-warnings which could be heard in the upper-deck cabin, then buffeting, followed by two separate stalls during which the aircraft descended rapidly, losing "several thousand feet" in controlled airspace. SIA would admit only to an unexplained loss of airspeed followed by a pilot decision to descend to increase speed.
One of the pilot passengers reported that some flight attendants were thrown off their feet and that drinks hit the cabin ceiling.
An SIA source says that the pilot and co-pilot were puzzled by an apparent disparity in the airspeed readings of their respective instruments - one of which appeared to be receiving "frozen" speed data. The incident occurred as they tried to decide which instrument was giving correct readings.
Boeing says: "Working with the customer airline and equipment manufacturers, we performed tests on aircraft equipment which we thought might have contributed to this anomaly. We examined the air- data computer, pitot-static probe systems and other equipment. Nothing was discovered that would explain the anomaly.
"The equipment was removed and replaced, pitot-static lines drained and flushed, and the aircraft returned to service. There has been no recurrence." Boeing adds: "We're still working with the airline to see whether we can determine the cause. We have not been informed of other instances like this."
from: Flight International
(apologies if this is off-topic, but it does cite a possible pitot issue)
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Time to switch to another thread?
May I respectfully suggest that the anticipated official report presents a great opportunity to freeze this thread and start another one. Ideally starting the new thread with a link to the official report.
What is the general feeling? I feel that 132 pages is already long enough.
Regards, Peter
... and many thanks to all the informative posters who have enlivened this investigation so far.
What is the general feeling? I feel that 132 pages is already long enough.
Regards, Peter
... and many thanks to all the informative posters who have enlivened this investigation so far.
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Already a long thread on the tech forum
http://www.pprune.org/tech-log/37688...tot-tubes.html
http://www.pprune.org/tech-log/37688...tot-tubes.html
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Hi,
Great idea 
But I suspect .. all the elements of the first official report are almost already in all the messages of this thread
I don't hold my breath for this reports and I think many will not discover new things in.
What will be interesting is the answers to the questions of the journalists (journalists only allowed to be in the meeting room .. no place for famillies .. pilot unions representatives .. etc ..)
Bye.
May I respectfully suggest that the anticipated official report presents a great opportunity to freeze this thread and start another one. Ideally starting the new thread with a link to the official report.
But I suspect .. all the elements of the first official report are almost already in all the messages of this thread
I don't hold my breath for this reports and I think many will not discover new things in.
What will be interesting is the answers to the questions of the journalists (journalists only allowed to be in the meeting room .. no place for famillies .. pilot unions representatives .. etc ..)
Bye.
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Mad Scientist
I think that the Agencies interpretation is that the fleet need to be grounded if there is 1 every 1.000.000 FH possibility that the problem leading to a catastrophic event can happen ; it is obviously not necessary to wait and see if the catastrophic event happens.
Reading the thread, it seems to me that many similar occurencies already happened to many of 330/340, and maybe, by pure luck or lack of coincidence of other events, those occurencies never became a 'catastrophe'.
Reading the thread, it seems to me that many similar occurencies already happened to many of 330/340, and maybe, by pure luck or lack of coincidence of other events, those occurencies never became a 'catastrophe'.
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Funfly
Absolutely correct. That's why on many light aircraft pitot tubes are heated (although on my first aeroplane, a venerable Rallye 100, it wasn't). It didn't really matter, I never flew in conditions where icing might have been a problem.
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Daniel_11000
Of course you don't wait to see if you actually exceed the "guideline" But you do consider the likely combinations of all the known causal factors. And if you don't have enough data than you take a more conservative approach with presuming these combinations. That's why the feds are investigating other related events to see what combines together good and bad.
This kind of analysis goes on all the time in large fleets in a proactive manner before a catatastrophe has even happened.
The fact that the AF accident has happened suggests that there is truly something different from our assumptions to be learned here. If that ingredient is so significant than we need to also consider it in combination with other minor system failures as well.
I say again, don't get too wrapped up in simplified theories about pitot tubes.
it is obviously not necessary to wait and see if the catastrophic event happens.
Reading the thread, it seems to me that many similar occurencies already happened to many of 330/340, and maybe, by pure luck or lack of coincidence of other events, those occurencies never became a 'catastrophe'.
Reading the thread, it seems to me that many similar occurencies already happened to many of 330/340, and maybe, by pure luck or lack of coincidence of other events, those occurencies never became a 'catastrophe'.
This kind of analysis goes on all the time in large fleets in a proactive manner before a catatastrophe has even happened.
The fact that the AF accident has happened suggests that there is truly something different from our assumptions to be learned here. If that ingredient is so significant than we need to also consider it in combination with other minor system failures as well.
I say again, don't get too wrapped up in simplified theories about pitot tubes.
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Non-conforming Failure
When the ACARS report shows ADR Fail, it does not have to be all the outputs failed, just any single output. Failed airspeed calculation does not cause a fail of the altitude output.
I'm still perplexed by the TCAS Fail report in the list. ATC/TCAS use altitude, not airspeed. The other incidents did not mention loss of altitude display. In one instance, it was noted the altitude indicated a drop of 300 feet, meaning the ADR was still outputting valid altitude calculation, but perhaps without airspeed trim.
I'm still perplexed by the TCAS Fail report in the list. ATC/TCAS use altitude, not airspeed. The other incidents did not mention loss of altitude display. In one instance, it was noted the altitude indicated a drop of 300 feet, meaning the ADR was still outputting valid altitude calculation, but perhaps without airspeed trim.
Last edited by Jetdriver; 26th Jun 2011 at 11:18.
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AP disengagement
Hi there,
A little question about the AP disengagement. On the graphs at the end of
http://www.atsb.gov.au/publications/...070_prelim.pdf
(report on Qantas incident), we can see that when AP1 disengaged, a drift in altitude was initiated and it seems to be corrected (see also elevator position) only when the AP2 was engaged: is it common when the AP goes off, that a drift is being observed on flight parameters ?
Jeff
A little question about the AP disengagement. On the graphs at the end of
http://www.atsb.gov.au/publications/...070_prelim.pdf
(report on Qantas incident), we can see that when AP1 disengaged, a drift in altitude was initiated and it seems to be corrected (see also elevator position) only when the AP2 was engaged: is it common when the AP goes off, that a drift is being observed on flight parameters ?
Jeff
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On most a/c the AP is never entirely "in trim" - there will be servos holding small amounts of torque - just as a pilot hand-flying may not be perfectly in trim, just holding a residual force.
So when an AP (any AP) disengages, it's likely the aircraft will drift slightly to the trim position. Since the AP commanded trim usually lags the aircraft behaviour, you can usually predict the direction of the drift as being a reversal of the most recent aircraft trends.
So when an AP (any AP) disengages, it's likely the aircraft will drift slightly to the trim position. Since the AP commanded trim usually lags the aircraft behaviour, you can usually predict the direction of the drift as being a reversal of the most recent aircraft trends.
Mad(Flt)Scientist;
Of course it isn't.
lomapaseo;
Exactly.
Professorah;
Mostly agree. It may be instructive to compare nevertheless. Where there are similarities they are political, not technical.
Oddly, the DC10 was grounded not after the Paris cargo door accident, the third time that failure of the cargo door had caused the collapse of the cabin floor indicating a serious and fundamental design flaw (which had been communicated after the first failure), but after the Chicago accident in which no design fault was found concerning the pylon structure. In other words, the grounding was political, not technical or directed towards flight safety.
There were design flaws in the cargo door which became evident during testing before the aircraft went into service. The forward cargo door on fuselage #1 blew open and a larg section of cabin floor collapsed. the problems were recognized but rather than re-design the door to a much safer plug-type installation, (such as the L1011), minor fixes were made but proved ineffective.
After the Windsor accident in which a cargo door blew open (about a month after the airplane entered service), and the floor collapsed, the FAA made a "Gentleman's Agreement" to fix the cargo door to avoid the embarrassing impact on sales that an AD would have. They issued a regular Service Bulletin instead, failing to avoid the Paris accident.
A year after the Paris accident the FAA issued an AD concerning the ability of cabin floors to withstand the differential pressure caused when one side of the pressure vessel lost pressure. This was accomplished through a combination of strengthened cabin floor structure and pressure relief (vent) valves.
The Chicago accident had nothing to do with the cargo door and the pylon design did not have problems in and of itself but was criticized for being vulnerable to maintenance damage, (fracture due to tight clearances) if improper maintenance procedures were used during engine/pylon changes. American Airlines and Continental Airlines had used non-standard methods for complying with Service Bulletins for the replacement of the rear spherical bearing engine mount.
The A330 pitot system per se does not have design flaws of anywhere near the same order as the design problems of the DC10. The pitot system does not have design flaws at all, in the sense that clear and present risk or vulnerability is demonstrated.
Someone mentioned 32 events but did not list them or describe them. They should be part of the present investigation and reviewed to see if there are larger issues at work or if this is component related.
Even with components examined, as lomapaseo correctly states, this is not a "pitot system" accident.
This accident is extremely complex and would be even if we had the boxes. Systems and components fail and aircrews are trained to respond to such failures.
Whether there are larger questions about design complexity and crews' ability to successfully respond and contain cascading system faults is not a matter over which an aircraft would (or should) be grounded but a matter which must be sorted out both within EASA and Airbus as well as other stakeholders such as airlines and aircrew representatives, especially those whose specialties are flight safety.
The aircraft isn't going to be "grounded".
lomapaseo;
I say again, don't get too wrapped up in simplified theories about pitot tubes.
Professorah;
The DC 10 was a totally different problem and should not be compared in anyway.
Oddly, the DC10 was grounded not after the Paris cargo door accident, the third time that failure of the cargo door had caused the collapse of the cabin floor indicating a serious and fundamental design flaw (which had been communicated after the first failure), but after the Chicago accident in which no design fault was found concerning the pylon structure. In other words, the grounding was political, not technical or directed towards flight safety.
There were design flaws in the cargo door which became evident during testing before the aircraft went into service. The forward cargo door on fuselage #1 blew open and a larg section of cabin floor collapsed. the problems were recognized but rather than re-design the door to a much safer plug-type installation, (such as the L1011), minor fixes were made but proved ineffective.
After the Windsor accident in which a cargo door blew open (about a month after the airplane entered service), and the floor collapsed, the FAA made a "Gentleman's Agreement" to fix the cargo door to avoid the embarrassing impact on sales that an AD would have. They issued a regular Service Bulletin instead, failing to avoid the Paris accident.
A year after the Paris accident the FAA issued an AD concerning the ability of cabin floors to withstand the differential pressure caused when one side of the pressure vessel lost pressure. This was accomplished through a combination of strengthened cabin floor structure and pressure relief (vent) valves.
The Chicago accident had nothing to do with the cargo door and the pylon design did not have problems in and of itself but was criticized for being vulnerable to maintenance damage, (fracture due to tight clearances) if improper maintenance procedures were used during engine/pylon changes. American Airlines and Continental Airlines had used non-standard methods for complying with Service Bulletins for the replacement of the rear spherical bearing engine mount.
The A330 pitot system per se does not have design flaws of anywhere near the same order as the design problems of the DC10. The pitot system does not have design flaws at all, in the sense that clear and present risk or vulnerability is demonstrated.
Someone mentioned 32 events but did not list them or describe them. They should be part of the present investigation and reviewed to see if there are larger issues at work or if this is component related.
Even with components examined, as lomapaseo correctly states, this is not a "pitot system" accident.
This accident is extremely complex and would be even if we had the boxes. Systems and components fail and aircrews are trained to respond to such failures.
Whether there are larger questions about design complexity and crews' ability to successfully respond and contain cascading system faults is not a matter over which an aircraft would (or should) be grounded but a matter which must be sorted out both within EASA and Airbus as well as other stakeholders such as airlines and aircrew representatives, especially those whose specialties are flight safety.
GB;
This may help:
I'm still perplexed by the TCAS Fail report in the list. ATC/TCAS use altitude, not airspeed. The other incidents did not mention loss of altitude display. In one instance, it was noted the altitude indicated a drop of 300 feet, meaning the ADR was still outputting valid altitude calculation, but perhaps without airspeed trim.
From Graybeard:
Right, an uncorrected altitude has an error magnitude of a few hundred feet. That may be considered unacceptable for TCAS since RAs occur for an anticipated vertical separation of only 700 ft (above 20,000 ft).
In one instance, it was noted the altitude indicated a drop of 300 feet, meaning the ADR was still outputting valid altitude calculation, but perhaps without airspeed trim.
Will Fraser;
That would be manufacturers, plural, because no transport, McD-D, Boeing, Lockheed or Airbus that I've flown provides this capability, nor does the historical accident record indicate the requirement, nor does an occurence necessarily prove the need.
We have yet to see if there is a design issue with the ISIS.
Re your suggestion to Rubik, fully-gimballed gyros still topple.
it is inconceivable that a major Manufacturer would ignore the need to provide handling cues to a blind FD.
We have yet to see if there is a design issue with the ISIS.
Re your suggestion to Rubik, fully-gimballed gyros still topple.
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PJ2
With a demonstrable history of trouble with flight cues under repetitive situations of AirData anomaly, this accident suggests the reason all prior incidents had acceptable outcomes was merely that the (447) flying pilots had no horizon, no a/s, etc. and were in weather at night. If I read you correctly, you are saying no manufacturer addresses this issue with mitigating (albeit archaic) solutions? That correct?
With a demonstrable history of trouble with flight cues under repetitive situations of AirData anomaly, this accident suggests the reason all prior incidents had acceptable outcomes was merely that the (447) flying pilots had no horizon, no a/s, etc. and were in weather at night. If I read you correctly, you are saying no manufacturer addresses this issue with mitigating (albeit archaic) solutions? That correct?
Per Ardua ad Astraeus
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This discussion is actually going http://www.pprune.org/safety-crm-qa-...-aviation.html this way - can I elicit any inputs there?
Will;
If the standby instruments fail, (which there is question of in the 447 ISIS case), there is no other system, archaic or no, and the mechanical standbys in the 320, 330 and 340 were tiny, poorly lit and would be impossible to read in heavy turbulence. These instruments are certainly not going to help you inside a thunderstorm. The B767 standbys were marginally better, (larger) and the L1011's were good, (well lit, readable). The DC8 - 60 series had a standby horizon. A standby altimeter was installed to "permit dispatch capability in the event that the air data computer or servoed altimeter fails." I don't think the DC9 had standby's but I can't recall now.
What I am pleading is the case for examining in detail the recorded issues to see the pattern or common thread if there is one, from which, I think you'd agree, the problem can be defined and if chronic, fixed, and if intermittent and statistically granular, addressed strategically. In part this has already been accomplished with the Unreliable Airspeed memory items and QRH checklist.
I think you need to understand that no bread-and-butter "archane" system presenting basic attitudes/speeds etc is going to right an aircraft or permit the crew to manually do same, that is badly upset.
What such a system must do, (and in my view it requires good flight conditions to do it for the reasons stated, "good" being in cloud, at night, no moon, no visible horizon, possible icing and moderate turbulence) is provide a horizon and a direct speed indication until the crew can stabilize the aircraft.
I can assure you that no instrumentation no matter how robust and no autoflight system will permit safe flight inside, or even offer a good chance of surviving penetration of, a large, developing thunderstorm at high altitude by a transport category aircraft. No pilot, no designer, no certification body and no regulator has a right to expect that any airliner should perform otherwise. If one enters a thunderstorm, one is, for all intents and purposes, in test-pilot territory with an unknown outcome.
If I read you correctly, those are however, the assurances you seek. That correct? If not, we're misconnecting and you need to be more specific and clear.
If the standby instruments fail, (which there is question of in the 447 ISIS case), there is no other system, archaic or no, and the mechanical standbys in the 320, 330 and 340 were tiny, poorly lit and would be impossible to read in heavy turbulence. These instruments are certainly not going to help you inside a thunderstorm. The B767 standbys were marginally better, (larger) and the L1011's were good, (well lit, readable). The DC8 - 60 series had a standby horizon. A standby altimeter was installed to "permit dispatch capability in the event that the air data computer or servoed altimeter fails." I don't think the DC9 had standby's but I can't recall now.
What I am pleading is the case for examining in detail the recorded issues to see the pattern or common thread if there is one, from which, I think you'd agree, the problem can be defined and if chronic, fixed, and if intermittent and statistically granular, addressed strategically. In part this has already been accomplished with the Unreliable Airspeed memory items and QRH checklist.
I think you need to understand that no bread-and-butter "archane" system presenting basic attitudes/speeds etc is going to right an aircraft or permit the crew to manually do same, that is badly upset.
What such a system must do, (and in my view it requires good flight conditions to do it for the reasons stated, "good" being in cloud, at night, no moon, no visible horizon, possible icing and moderate turbulence) is provide a horizon and a direct speed indication until the crew can stabilize the aircraft.
I can assure you that no instrumentation no matter how robust and no autoflight system will permit safe flight inside, or even offer a good chance of surviving penetration of, a large, developing thunderstorm at high altitude by a transport category aircraft. No pilot, no designer, no certification body and no regulator has a right to expect that any airliner should perform otherwise. If one enters a thunderstorm, one is, for all intents and purposes, in test-pilot territory with an unknown outcome.
If I read you correctly, those are however, the assurances you seek. That correct? If not, we're misconnecting and you need to be more specific and clear.
Last edited by PJ2; 1st Jul 2009 at 19:22. Reason: Add information re "other manufacturers"
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BEA press point on the 02/07
I think and hope that one or both of these French newsTV will live cover the press conference. As a reminder between 15 and 17hrs local 13/15UTC.
ITELE - ACCUEIL
There's a short advertising just before the live brodcasting.
BFM TV la nouvelle chaīne de l’information sur la TNT, le cāble, le satellite et l'ADSL
about 30 sec delay
There might be others.
ITELE - ACCUEIL
There's a short advertising just before the live brodcasting.
BFM TV la nouvelle chaīne de l’information sur la TNT, le cāble, le satellite et l'ADSL
about 30 sec delay
There might be others.
