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Originally Posted by augustusjeremy
(Post 5012153)
From the plots in the qantas preliminary report
http://www.atsb.gov.au/publications/...070_prelim.pdf a) IR1 fault is detected but the A/C continues in normal law even after master PRIM becomes PRIM2; b) When master PRIM is switched back to PRIM1 then the a/c gets into Alternate Law and the crew regains control. Jeff |
A body may well float in such circumstances from the first moment of immersion. The ocean temperature will be a factor. The sea was warm (in the region of the high 20s C) so flotation would be possible. A cold body will generally sink and stay down, often in the same area where it was immersed.
Assistance of flotation support, whether intentional or not, may be a factor in the bodies remaining on the surface. |
yes and the IR1 fault was 10 sec. before the ADR1 failure for Qantas, the two faults maybe within the same minute for the AF447. why this IR1 is declared faulty whereas it is its ADR part which is providing erroneous AoA measurements ? where there identified problems with the gyrometers/accelerometers afterward ? It does not appear so. Jeff OEB N° Page 2 of 5 74/4 REASON FOR ISSUE: This OEB is issued in order to provide a procedure enabling to mitigate the probability of occurrence of a sudden nose down order. EXPLANATION: An A330 aircraft experienced a sudden nose down order during cruise. This order was preceded by an automatic autopilot disconnection and triggering of the NAV IR 1 FAULT ECAM caution. Investigations highlighted that at the moment of the event the ADR 1 was providing erroneous and temporary wrong parameters in a random manner. This abnormal behavior of the ADR 1 led to several consequences such as unjustified stall and over speed warnings, loss of attitude information on the Primary Flight Display, several ECAM warnings. Among the abnormal parameters, the provided Angle of Attack value was such that the flight control computers commanded nose down movement. The aim of the following procedure is to isolate both the IR and ADR when an IR is detected faulty in order to prevent the ADR from providing erroneous data to other aircraft systems. TO BE CONTINUED ON NEXT PAGE PROCEDURE: RRRR OEB N° Page 3 of 5 74/4 RRRR If all ADIRU operative before failure: If one IR is self detected faulty or if the ATT red flag is displayed on the Captain or First Officer PFD, the affected IR and the corresponding ADR must be disconnected. NAV IR 1(2)(3) FAULT, or ATT flag displayed on CAPT (F/O) PFD -IR (affected) pb .. OFF The affected IR is the one self-detected faulty or supplying the PFD displaying the ATT red Flag. The OFF light may not illuminate -ADR (corresponding) pb .. ... OFF ADR 1 corresponds to IR 1. ADR 2 corresponds to IR 2. ADR 3 corresponds to IR 3. The OFF light may not illuminate -IR (affected) MODE rotary selector .. OFF The IR mode rotary selector is set to OFF in order to de-energize the ADIRU. The OFF lights of the IR and ADR pushbutton will go off. Setting the IR mode rotary selector to OFF is an irreversible action. Therefore, both PF and PNF must clearly identify the corresponding selector before setting it to OFF. If IR 1(2) affected: In order to prevent possible failure of ADIRU 3, the flight crew must switch the AIR DATA and the ATT HDG in the following order: -AIR DATA SWTG ........ .. ... CAPT (F/O) ON 3 -ATT HDG SWTG .. ....... .. CAPT (F/O) ON 3 |
The comments on what has been recovered is interesting, but what is more interesting is what has not been found. I have not seen many seats, seat cushions, personal effects, clothing, carry on items, cargo items and/or baggage, the myriad of paper items which are carried on the airplane, galley stores, and the list goes on. All this leads me to believe that the airplane entered the water mostly intact. This is further supported by the lack of a large debris field. Had there been a catastrophic failure at altitude, one could expect a long trail of items floating on the surface. To my knowledge, this has not been the case.
The discovery of the L2_R2 galley in good condition, along with the lav door, the FA seats, the defibrillator, could indicate a failure of the fuselage upon contact with the water. Other than the VS, it seems most of the items recovered have come from around the L2 interior and exterior section. The airplane could be in two separate parts which could account for some of these items retrieved in good condition. |
Originally Posted by PJ2
is this the post you're referring to,
A different question for those familiar with that route. From what I can make out in terms of where this might have occurred in the actual area of CB activity, carrying on on track after 'recovery' from whatever happened would appear to be a better weather solution than turning back to the mainland. How would this fit with a possible 'worse case' ETOPS fuel scenario ie low level 2 engines vis a vis ETPs and excess fuel, and where would ETP 1 be likely to be in relation to TASIL? |
The discovery of the L2_R2 galley in good condition, along with the lav door, the FA seats, the defibrillator, could indicate a failure of the fuselage upon contact with the water. Other than the VS, it seems most of the items recovered have come from around the L2 interior and exterior section. The airplane could be in two separate parts which could account for some of these items retrieved in good condition. |
There have been one or two comments about the containers and the condition of the galley being in good order.
I'm sure that many of you know how relatively feeble is the retaining mechanism for the galley containers, how often they come adrift even after a gentle landing. Imagine then, an aircraft breaking up in flight, various parts spinning and spiralling into the sea, almost inevitably with considerable force; would those containers really still be there, in their stowed position? It would also be interesting to know how much water they contained as it might be indicative of how deep they went before surfacing, and whether the buoyancy of the structure to which they were secured was sufficient to bring them to the surface if they were water logged. To me it is more suggestive of an aircraft breaking up on contact with the sea. |
ir2/ir3
In order to prevent possible failure of ADIRU 3, the flight crew must switch the AIR DATA and the ATT HDG in the following order: -AIR DATA SWTG ........ .. ... CAPT (F/O) ON 3 -ATT HDG SWTG .. ....... .. CAPT (F/O) ON 3 I think I know what you mean. There are some differences from the qantas 72 case, though. They kept at normal law almost to the end of the flight. AF447 switched to alternate law. I still don't understand why the qantas a/c kept in normal law and at the same time it kept using the faulty IR1/ADR1 data. In alternate law there is still (it seems) some protection regarding AoA but it can be overriden by the crew. Anyway if AF447 was wrongly informed about their speed the situation would still be dangerous (I suppose). Can't be sure about the pitots message... Maybe one pitot was already blocked... I don't know how this problem is detected.... Nothing from the Pitot Heat Computer specification to get any valuable hint. The aim of the following procedure is to isolate both the IR and ADR when an IR is detected faulty in order to prevent the ADR from providing erroneous data to other aircraft systems. This is complicated stuff... |
if two ADR disagree, as it was the case for the Air Caraοbe and the AF 447 flights, normal law should irreversibly switch to alternate law 2, if one ADR fails, it switches to alternate law 1 with possibility to revert to the normal law, as it was the was for the Qantas flight, 3 seconds after the 2nd pitch down.
this does not explain to me why a faulty ADR (how could it detect itself that it is generating erroneous measures ?) give rise to an IR failure when nothing anomalous is seen with it (does the post flight analysis show any defect with the IRU part ?). but this is nother problem. it simply suggests that faulty/disagreeing ADRs can trigger IRU fault reports and alternate law 2 (plus a strange behaviour of the autopilot) Jeff |
quaeler;
They recovered the overhead baggage facade for the right rear of the cabin, as well; i haven't seen any photos of something i could recognize from the middle space of the cabin. http://i277.photobucket.com/albums/k...eOnBoat3-1.jpg and, http://i277.photobucket.com/albums/k...nBoat4pg-1.jpg |
An inference can be drawn from any piece of evidence be it physical, electrronic or witnessed, and I feel that the inference must be compared to the benchmark of "consistency" in that any inference drawn must be consistent with the other inferences from facts already known. Speculation is fine, (even essesntial) if we maintain scrupulous adherence to consistency then a clearer view will reveal itself. Perhaps you've misunderstood the thrust of my post, or maybe I simply haven't stated it well enough. I would agree with you entirely that there are some inferences that can be drawn from each piece of evidence, and I am certainly not suggesting that these should be discounted. However, I would say that the inference drawn has something to do with the level of expertise one has with the particular element of evidence, and this is where different contributors here each bring different strengths (and weaknesses). Personally I know very little about the failure modes of vertical stabilizers/attach points and know nothing about rates and directions debris spread based on current movement, so I'll leave the inference drawing on such matters to others better educated to do so. When they do, with consistency to known facts, it makes for a valuable contribution to the discussion and that's certainly to be encouraged. It may also provide the rest of us a link back to another area where we can provide informed speculation that comes to make more sense in context with that contribution. Where things have occasionally gone wrong is with incorrect inferences being elucidated by some without particular expertise and those inferences then being extrapolated into conclusions of what happened and/or why without there being any actual facts to support either the inference or the conclusions derived from it. I'm not sure if you've followed the entire thread but, at times, there have been some pretty strongly worded conclusions about what type of design/system/software/crew error must have been responsible for this accident and how this represents a particular failure of the manufacturer/operator/crew. It's these sort of speculations, not reasoned, informed and factually supportable ones such as you are suggesting, that I have been referring to. In any event, what I think we all hope to achieve from the discussion is a better understanding of all the circumstances surrounding this accident and how that greater knowledge might improve our own procedures and decisions when confronted with similar circumstances as a pilot/passenger/dispatcher/engineer/designer or even accident investigator. Cheers, ELAC |
Originally Posted by "FlexibleResponse:
Very good investigative work! I think you also need to take into account that the human body does not float in seawater until about 72 hours after death. Then there should be some allowance for the time from establishing positive buoyancy to float from the wreckage at the bottom of the ocean up to the surface. Again some allowance should be made for the average sea current during the ascent time (unlikely to be the same as the surface current). So finally it could be possible that the surface drift time before discovery of the first body could have been less than 24 hours...this might put the wreckage very close to the flight plan track?
This is an interesting point which may indeed affect my estimation but, as a matter of fact, the human body, with a gravity below 1 (clear water), is naturaly buoyant. In salted sea water it is even more buoyant but temperature, etc. are other factors changing sea water density. On the other hand, there will be also some variation with the sex, age, clothes, mutilations, etc. of the victims. So several paramaters will affect how much of the body will surface (very few percent indeed until the decomposition process is well advanced). Next, decomposition at sea will start to increase buoyancy immediately following death. There is no need to wait for 72 hrs, it is just a matter of equilibrum between the body state and the sea density. S~ Olivier (Note: I already tried to post twice an answer but my posts didn't show up after many hours. I hope this one will go thru.) |
ELAC
Thank you for your comments. Its clear that we agree on many things. It ws my intention to add detail to your comments and not to decry them. My knowledge of such things as vertical stabilisers could be written on the back of a postage stamp, and yes, you are right that some know an awful lot about them. In the main Ive found that the posters who do know what they are talking about have presented things in a clear and unambigous manner. There have been some very confident explanations as to why AF447 got into difficulties. What seperates the wheat from the chaff in these opinions is whether they are consistent with known facts. The problem being that known facts in this case are very few in number. |
For what it's worth, fuselage failure on contact with the water makes more sense to me too. I'd have expected more impact damage to the galley if it was ejected in an in-flight breakup and hit the water in free fall. Maybe someone with real knowledge will explain that it's strong and light enough to survive such an event undamaged, but that doesn't seem too likely on its face.
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Problem posting in this thread
Sorry everybody,
I already answered three times the questions about my maps but the system fails to show my post. Is quoting someone delaying the post? Thx, Olivier (Edit: I guess as this post appeared immediately!) |
The Brazilian Air Force's site has this plot for retrieval of wreckage on June 3. The Brazilian AF charts for search and recovery effort begin with two maps for early wreckage recovery, one is undated. (The undated chart has wreckage recovery 160 km WNW of Sao Pedro and Sao Paulo.) Both maps look to be overlays on aeronautical charts.
See very large image here: http://www.fab.mil.br/portal/voo447/...a_voo447_2.jpg However, it seems likely that that the 'wreckage' retrieved on June 3 was ultimately identified as not coming from AF447. On June 6, the first wreckage definitively identified as coming from AF447 was located at 03.34.08' N and 030.27.30' W. It is a seat cushion (poltrona) with a serial number. A male corpse is also recovered (apparently from the same area as the seat cushion). The position is WNW of the last reported position. Another male body is recovered later in the day from this area. See Powerpoint slides at: http://www.fab.mil.br/portal/voo447/...a_06_06_09.ppt The Brazilian Air Force site also has a plot for the recovery of the 50th body showing location from where 19 bodies were recovered. On June 20th, ENE of the 50th body, and NNE of Tasil, there was recovery of "Despojo". (Despojo means spoils, might it mean body psrts?) For plots of the early search and rescue patterns, and weather in the general area from June 6 onward, and for various charts including those cited above, see: FORΗA AΙREA BRASILEIRA - Asas de um povo soberano Thanks to takata for finding the link. ____________________________________________ Edited to add this image of a section of a Brazilian Air Force Powerpoint slide indicating where 'wreckage' was located on June 2. I think none of this wreckage was ultimately identified as being from AF447. But it does show what was located in an area takata thinks the plane might have crashed if a 180 turn toward Sao Pedro and Sao Paulo was attempted. http://i136.photobucket.com/albums/q.../SNAG-0290.jpg ___________________________________________ Second edit to add the search grids by date. They were looking mostly to the east of the track. June 1 search grids: http://i136.photobucket.com/albums/q.../SNAG-0292.jpg June 2 search grids http://i136.photobucket.com/albums/q.../SNAG-0294.jpg June 3 search grids http://i136.photobucket.com/albums/q.../SNAG-0295.jpg June 4 search grids http://i136.photobucket.com/albums/q.../SNAG-0296.jpg June 5 search grids http://i136.photobucket.com/albums/q.../SNAG-0297.jpg June 6 search grid, showing grid that first located definite AF447 wreckage and bodies. http://i136.photobucket.com/albums/q.../SNAG-0298.jpg The early, unproductive searches to the east of the track suggest that AF447 did not turn east and south toward Sao Pedro and Sao Paulo. Unknown why there was no early searching west of the track or northwest of the last reported position. I don't believe the green circle in the June 4 and June 5 maps is a search grid. And the grids for June 2 -- June 5 look to be cumulative, not repetitive. |
qantas
as it was the was for the Qantas flight, 3 seconds after the 2nd pitch down. What I see in the qantas plots is an a/c leaving normal law only when the PRIM1 is set to master. Looks like an abnormal behaviour with a faulty IR1/ADR1 input. Either it should be in normal law with ADIRUS2 and 3 or it should leave it to alternate law |
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The "Human factor"(ie.correct diagnosis followed by correct transfer switching,inadvertent shutdown of a good unit etc) theory following ADIRU event(Aguadalte) needs much closer scrutiny IMHO.What those Qantas pilots had to go through is above and beyond the normal scope of "airline pilot".
As can be seen, the Captains Primary Flight Display usually presented data from ADIRU 1, following the presentation of the NAV IR1 FAULT, the source of data was switched to Inertial Reference unit 3 on ADIRU 3. However, this did not automatically switch the source for Air Data References, which continued to be ADIRU 1. This illustrates the complexity of interaction with redundant systems as crews struggle to ensure that they receive data from a reliable source without knowing for sure which of the alternate ADIRUs is providing reliable information. The problems with the Captains Primary Flight Display could not be resolved before a second uncommanded pitch down. The uncertainty created by crew interaction with their redundant systems was exacerbated by the way in which the master flight control primary computer was switched from PRIM1 to PRIM 2 following the first pitch down event. The subsequent indication of a fault on PRIM 3 then triggered a further change in the master from PRIM 2 back to PRIM 1 and it was only in subsequent discussions with the operators maintenance watch unit in Sydney, while the flight was still in the air that the crew decided to switch off PRIM 3. |
Good link Rananim
The last line is almost prophetic. "It would appear that the crew were able to benefit from the lessons learned in the previous incident; however, it is also clear that we have further lessons to learn in the application of advanced redundancy techniques for safety-critical software." AF447 may turn out to be the next lesson. |
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