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Old 21st Jan 2014, 20:54
  #341 (permalink)  
 
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@Winnerhofer
And Concorde,
And Toronto
And unknown incidents

@rudderruddererrat
Thanks for the link. I hope A and B will continue these meetings with ICAO

@Hazelnuts39
I agree with your doubts.Who decided but Airbus themselves the special 1988 conditions replacing the regulators.


Does anybody know the certification date of Airbus in Vietnam (ref for USA...)?
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Old 21st Jan 2014, 20:59
  #342 (permalink)  
 
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Originally Posted by roulishollandais View Post
@Hazelnuts39
I agree with your doubts.Who decided but Airbus themselves the special 1988 conditions replacing the regulators.
In 1988 Capt. Gordon Corps (of the Air Registration Board and its successor, the Design and Manufacturing Group of the Airworthiness Division of the Civil Aviation Authority) was in charge of that work. At that time he was still an independent consultant and not an Airbus employee.
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Old 21st Jan 2014, 22:13
  #343 (permalink)  
 
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Originally Posted by roulishollandais
Who decided but Airbus themselves the special 1988 conditions replacing the regulators.
Another poster and I have been quoting from the FAA Special Conditions for the A320. These have followed the normal FAA process of rulemaking. A Notice of Proposed Special Conditions was published in the Federal Register on October 19, 1987. The comments received from the public in response to that notice are discussed in the preamble of the final rule. Regarding the reference stall speed the A320 Special Conditions are largely identical to the current standard of the regulation, proposed in 1995 and adopted in 2002 with FAR Amendment 25-108.

Many people from airworthiness authorities, manufacturers, operators and pilot associations in the U.S., Canada and Europe participated in the development of those changes in the regulations. In fact it would be difficult to identify a manufacturer of transport category airplanes or its regulatory agency that was not involved in that process. I doubt that any of those individuals would have claimed to be 'in charge of that work'.

Last edited by HazelNuts39; 21st Jan 2014 at 23:08.
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Old 22nd Jan 2014, 12:43
  #344 (permalink)  
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Time stamps and DFDR/CVR synchronisation

Quote from me:
"...I'm still inclined to the theory that TGEN 000.0 seconds is most likely to be the instant that TOGA was selected on T/O."
Quote from CONF_iture:
"It would be surprising that TOGA or FLEX has been selected before any takeoff clearance..."

Yes, I should have done the arithmetic! That puts TGEN 000.0 seconds at 1240:05z, and T/O clearance was not issued until 1240:40z.

We know that movement of the throttle levers through the various thrust-limit gates, as necessary for the selection of TOGA from idle, is audible on the CVR. My assumption was that TGEN 000.0 would have marked a point of synchronisation between the CVR and the DFDR, but there is nothing in the CVR transcript - such as a lever movement, or the start of a transmission on the R/T - to suggest any audible event at 1240:05z that would have been simultaneously recorded on the DFDR.

So it may be that TGEN 000.0 is a purely arbitrary point. The Airbus 1991 document explains that the CVR is not time-stamped, but that the CVR records at a steady speed. I infer that a minimum of two synchronisation points some minutes apart would be necessary, to enable the CVR and DFDR recordings to be synchronised for the whole flight. The selection of TOGA a few seconds before impact would appear to be one ideal example. **

BTW, I'm still reading Capt Asseline's account. My PDF is missing the Annexes. Can anyone steer me towards obtaining them, please?

** The selection of T/O thrust on take-off would be another.

Last edited by Chris Scott; 23rd Jan 2014 at 19:40. Reason: ** added.
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Old 22nd Jan 2014, 14:37
  #345 (permalink)  
 
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Originally Posted by Chris Scott
I infer that a minimum of two synchronisation points some minutes apart would be necessary, to enable the CVR and DFDR recordings to be synchronised for the whole flight.
The BEA has made every effort to confuse the situation and make sure that what should be simple and straightforward is ... NOT.
Clac Clic Cloc and even Crac ! are happily mixed all along ...

You can find the Annexes for Asseline book here :
Crashdehabsheim.net

Go to :
  • Bibliotheque
  • Le temoignage du pilote (telechargeable ici)
  • Telecharger les annexes
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Old 22nd Jan 2014, 15:08
  #346 (permalink)  
 
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Originally Posted by HazelNuts39 View Post
I doubt that any of those individuals would have claimed to be 'in charge of that work'.
Poor phrasing on my part - I put it down to a combination of exhaustion and jetlag.

Of course more people and organisations were involved, and I shouldn't have been so sloppy with my wording - but what I was trying to get at was that in Capt. Corps case at least, he was still primarily answerable to his CAA role in determining certification criteria and his role as a consultant would be driven by that as opposed to Airbus's corporate benefit (as rh seemed to be insinuating).

Originally Posted by CONF iture View Post
The BEA has made every effort to confuse the situation and make sure that what should be simple and straightforward is ... NOT.
Er - how are they doing that? If I've got this right, you're talking about an appendix with the raw data over which the BEA have very limited editorial control. Remember that DFDRs were a relatively new technology at the time, and as such best practices were still being determined*.

Apropos of nothing, I find it somewhat ironic that you are criticising the BEA for supplying raw data (which can be opaque and confusing) in this case, yet you were demanding the release of raw data on the AF447 threads and criticising the BEA for not doing so. It seems to me that they can never do right as far as you're concerned.

EDIT :

* - For one thing, the computerised data manipulation tools and techniques which we take for granted today weren't fit for purpose in 1988. These days microcomputers are powerful enough to import vast amounts of raw data into a spreadsheet, and aligning the data visually is as simple as clicking and dragging a mouse. In 1988 there was still a significant gulf between the mainframes and minicomputers used in industry and the microcomputers used in offices and homes. The storage of data in a binary format was far from standardised - and even if that hurdle could be overcome, spreadsheets were only used on microcomputers, the most powerful examples of which in 1988 didn't have the RAM to effectively manipulate that much data.

Last edited by DozyWannabe; 22nd Jan 2014 at 16:41.
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Old 22nd Jan 2014, 18:48
  #347 (permalink)  
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Hi ruderrudderrat,
Thanks for the link to that recent presentation on stall testing. Very interesting.

Quote from me:
"I agree with CONF_iture, however, that it would be good to see the DFDR for the whole flight."
Reply from Dozy Wannabe:
"Would you also say that while it may have been "good", it was nevertheless reasonable to truncate the published DFDR output to the time period relevant to the accident by the standards of the time?"

Yes. If not, I would have said "...would have been good..."

It would be useful, however, for the purpose of our present discussions, not least to improve our understanding of the data. I would like to see the T/O and climb, if only to observe the acceleration of the engines from idle to T/O thrust (presumably TOGA, but I haven't seen a reference to that, and the copilot's FMA call of "THR" is apparently anomalous, unless the PF had selected Flex Thrust with no "assumed temperature" entered in the FMGS), the height at which the right turn was initiated, and the changing status of A/THR.

Hello Confit,
Thanks for that link to the annexes in Capt Asseline's account.
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Old 22nd Jan 2014, 19:57
  #348 (permalink)  
 
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Originally Posted by Chris Scott View Post
It would be useful, however, for the purpose of our present discussions, not least to improve our understanding of the data. I would like to see the T/O and climb, if only to observe the acceleration of the engines from idle to T/O thrust...
Agreed, if only for the sake of completeness. However, the BEA's response to Capt. Asseline's correct assertion that the elevators briefly deflected down while he had the stick back was a thorough real-world reconstruction of the aircraft's commanded flightpath - an experiment entailing significant effort and expense*. Is it not therefore reasonable to infer that the BEA compared engine performance data at take-off and during the accident sequence against both each other and an optimum set of test data - and found no significant anomalies?

One thing that has always puzzled me about Capt. Asseline's responses in the aftermath of the accident is that the BEA's report, far from assigning the causes purely to the actions of the flight crew, actually implicitly hauls AF's operations practices over the coals - not just in terms of highlighting the woefully inadequate briefing materials, but also highlighting contradictory rules and regulations pertaining to conduct of display flights. Reading between the lines the report more-or-less implies a reasonable argument that the crew were almost set up to fail. Capt. Asseline and his lawyers could likely have turned this into the most clear-cut example of mitigating circumstances in history, and yet they ignored that angle in favour of going after Airbus. To me this makes so little sense that I can't begin to fathom out why.

EDIT :

* - To put the question from another angle, if the BEA were being pressured to go easy on AI, why go to all that trouble and expense when a verbal response with no experiment would have carried the same weight in an official sense?

Last edited by DozyWannabe; 22nd Jan 2014 at 20:59.
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Old 23rd Jan 2014, 00:49
  #349 (permalink)  
 
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Originally Posted by Dozy
I find it somewhat ironic that you are criticising the BEA for supplying raw data
Quote please ... ?

Originally Posted by Chris Scott
I would like to see the T/O and climb, if only to observe the acceleration of the engines from idle to T/O thrust (presumably TOGA, but I haven't seen a reference to that, and the copilot's FMA call of "THR" is apparently anomalous, unless the PF had selected Flex Thrust with no "assumed temperature" entered in the FMGS)
Except from the "Clac Clac" mentioned in the CVR transcript at time 12 41 04 which could possibly mean that the FLEX detent was the one used for the take off, I cannot remember anything explicitly mentioned in the report.

Also from Asseline's account on page 103 :
Pour décoller de Bâle-Mulhouse, j'avais positionné les manettes des gaz dans un cran intermédiaire (FLX MCT), déterminant une poussée réduite au décollage, de manière à économiser les moteurs tout en garantissant une poussée suffisante compte tenu de la masse réelle de l'avion.
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Old 23rd Jan 2014, 01:05
  #350 (permalink)  
 
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Originally Posted by CONF iture View Post
Quote please ... ?
Your post #336:

Originally Posted by CONF iture View Post
  1. Publish the photocopy of a copy of a copy ... of the original
  2. Not include the seconds of the GMT
  3. Add a TGEN for which I would not specify the origin
  4. Publish a limited amount of FDR data
  5. Publish those data for only a short period of that short flight

Points 2 and 3 in particular. You're looking at raw output right there - even if the technology existed to do so at the time, the BEA could not add GMT seconds or TGEN origin without by definition altering the data.

Additionally, your point 1 is likely just a consequence of the age of the document. The original digital files are likely locked away in an archive - the online version is purely for casual use, so digging the original up would likely not be cost-effective. Your point 5 is essentially the same as your point 4 and therefore redundant. Remember that the BEA is only charged with publishing data relevant to the accident. As I said above, if the engine performance at take-off and during the accident sequence was shown to be within normal limits, then there's no requirement for the BEA to publish it.
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Old 23rd Jan 2014, 01:06
  #351 (permalink)  
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Quote from Dozy Wannabe:
"Is it not therefore reasonable to infer that the BEA compared engine performance data at take-off and during the accident sequence against both each other and an optimum set of test data - and found no significant anomalies?"

If one believed beyond any doubt that the BEA carried out a wide-ranging, impartial, and fully-informed investigation, that would indeed be a reasonable inference. But it would cut no ice with the BEA's detractors, and the bureau itself is unlikely - if you'll forgive the understatement - to enter into discussion on any alleged deficiencies.

Alternatively, we can all accept the findings and suspend further discussion...
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Old 23rd Jan 2014, 01:28
  #352 (permalink)  
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Salut Confit,

I have not reached page 103 yet...

Your quote from Capt Asseline:
"Pour décoller de Bâle-Mulhouse, j'avais positionné les manettes des gaz dans un cran intermédiaire (FLX MCT), déterminant une poussée réduite au décollage [...]"

The CVR quotes the copilot's FMA call as "Thrust...", which happens to be abbreviated (as you know) to "THR" on the thrust FMA.

I therefore infer that the throttle levers were placed in the FLX/MCT gate (i.e., Flexible T/O thrust was commanded for take-off), but that no assumed temperature was presemt in the FMGS.

For other readers, the flexible-thrust "assumed temperature" is a device to order the engines to develop the lower T/O thrust associated with a higher ambient air-temperature than that pertaining on the day. It is calculated before departure as part of the T/O performance calculation, and entered manually into the PERF / Take-Off page of the FMGS by the flight crew. When the throttle levers are placed in the FLX/MCT gate for take-off, the thrust FMA should read "FLX nn", where "nn" is the assumed temperature, e.g., "FLX 53".

Last edited by Chris Scott; 23rd Jan 2014 at 16:07. Reason: Last sentence corrected. Spelling corrections and syntax improvements. 3rd para corrected, courtesy of CONF_iture's post.
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Old 23rd Jan 2014, 01:49
  #353 (permalink)  
 
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Originally Posted by Chris Scott View Post
If one believed beyond any doubt that the BEA carried out a wide-ranging, impartial, and fully-informed investigation, that would indeed be a reasonable inference. But it would cut no ice with the BEA's detractors, and the bureau itself is unlikely - if you'll forgive the understatement - to enter into discussion on any alleged deficiencies.
The issue as I see it is that most if not all of those "detractors" resort to obfuscating and, on occasion, outright misrepresenting the contents of the report in order to support their arguments. At the time, the lawyers representing Capt. Asseline and the SNPL union embarked on an almost unprecedented campaign to muddy the waters, briefing journalists with any allegation they could muster.

The ultimate outcome of this scorched-earth approach is that even people who are knowledgeable on the subject are frequently misinformed. I still hear talk of "the computer thought it was landing", "the autopilot was in command when it crashed" and "the report blamed the pilot" among other things - most of which, like those examples, are completely and demonstrably untrue.

Alternatively, we can all accept the findings and suspend further discussion...
If only...!

Seriously though, there's no such thing as a perfect report in the real world - but in my opinion the BEA performed an investigation that was at least as "wide-ranging, impartial, and fully-informed" as could be expected.
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Old 23rd Jan 2014, 09:03
  #354 (permalink)  
 
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Originally Posted by CONF iture
  1. Publish the photocopy of a copy of a copy ... of the original
  2. Not include the seconds of the GMT
RE 1: In those days the BEA didn't have facilities to read DFDR tapes and decode the data. The tape was read at the CEV (Centre d'essais en vol), the french military flight test centre, which also does civil certification test flying and houses the french national test pilot school. The print looks to me like it was produced on a IBM typewriter or daisy-wheel printer and published in the report as it was received from the CEV.
RE 2: The DFDR GMT parameter probably records only hours and minutes (remember the timestamp of the AF447 ACARS messages?). The seconds have to be determined by counting the frames, and fractions of a second from the parameter position within the frame word sequence. Who sets the GMT clock in the airplane? The wording of the note in the Airbus memo suggests that TGEN is not a recorded parameter but a frame count added in the CEV printout of DFDR data.

Last edited by HazelNuts39; 23rd Jan 2014 at 11:19.
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Old 23rd Jan 2014, 11:58
  #355 (permalink)  
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Quote from HN39,
"Who sets the GMT clock in the airplane?"

I reckon that's a rhetorical question, but I can confirm that it's anyone who is inclined to do so. We never did it in flight. According to the FCOM, its timings are "sent to the CFDIU, FDIU and FMGC." The FDIU, of course, feeds the DFDR.

Quote from Dozy Wannabe:
"One thing that has always puzzled me about Capt. Asseline's responses in the aftermath of the accident is that the BEA's report, far from assigning the causes purely to the actions of the flight crew, actually implicitly hauls AF's operations practices over the coals - not just in terms of highlighting the woefully inadequate briefing materials, but also highlighting contradictory rules and regulations pertaining to conduct of display flights. Reading between the lines the report more-or-less implies a reasonable argument that the crew were almost set up to fail. Capt. Asseline and his lawyers could likely have turned this into the most clear-cut example of mitigating circumstances in history, and yet they ignored that angle in favour of going after Airbus. To me this makes so little sense that I can't begin to fathom out why."

You make a very reasoned argument, and it may well be that Capt Asseline was badly advised. Union politics are far too complex for the likes of me.

Last edited by Chris Scott; 23rd Jan 2014 at 12:27.
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Old 23rd Jan 2014, 11:59
  #356 (permalink)  
 
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Originally Posted by rudderrudderrat
The above presentation suggests the aircraft is actually taken beyond CL Max, and its behaviour is observed in both Normal law and "Additional stalls performed with degraded control laws" (slide 35) to determine VS1g.
The presentation describes recent experience during testing of A380 and B787 and is looking toward the future. Slide 35 doesn't mention Vs1g.

Nothing in the presentation is in conflict with my position that the certified Vs1g for the A320 was determined in accordance with the Special Conditions for type certification of the A320: in normal law as designed for the production airplane except with alpha-prot disengaged. Additional tests were conducted with modified or degraded control laws to demonstrate stall characteristics and to obtain aerodynamic data beyond alpha-max (and probably beyond cLmax) for design purposes and for the flight simulator data package.

P.S.
This effectively means that the 1987 FCOM (Chris Scott #213) was in error when it said "alpha-max = alpha (1.06 Vs)".

Last edited by HazelNuts39; 23rd Jan 2014 at 17:01. Reason: P.S.
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Old 23rd Jan 2014, 13:43
  #357 (permalink)  
 
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@Hn39

Nothing in the presentation is in conflict with my position that the certified Vs1g for the A320 was determined in accordance with the Special Conditions for type certification of the A320: in normal law as designed for the production airplane except with alpha-prot disengaged. Additional tests were conducted with modified or degraded control laws to demonstrate stall characteristics and to obtain aerodynamic data beyond alpha-max (and probably beyond cLmax) for design purposes and for the flight simulator data package.
That makes sense. Those additional tests (with an increased alphamax so that it didn't interfere with the testing) would have come first to establish what alphamax might be and the certification tests then completed up to that alphamax/Vs1g as you suggest.
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Old 23rd Jan 2014, 15:44
  #358 (permalink)  
 
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Originally Posted by Chris Scott
The CVR quotes the copilot's FMA call as "THR...". That is presumably the transcriber's shorthand for the spoken word "Thrust...", which happens to be abbreviated (as you know) to "THR" on the thrust FMA.
Actually the CVR transcript is clear :
"Thrust SRS ! RUNWAY" at time 12 40 59

and the copilot's FMA call of "THR" is apparently anomalous, unless the PF had selected Flex Thrust with no "assumed temperature" entered in the FMGS
Anomalous I agree, as the call should have been either MAN FLX or MAN TOGA, but if no flex temp had been previously entered, and Asseline had set the thrust levers to the FLX detent, the ECAM ENG THR LEVERS NOT SET would have been triggered ... Was it different in 88 ?
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Old 23rd Jan 2014, 15:49
  #359 (permalink)  
 
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Originally Posted by Dozy
Your post #336
And where my post #336 is "criticising the BEA for supplying raw data" ?
All I can see is demanding for more ... not less.
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Old 23rd Jan 2014, 16:35
  #360 (permalink)  
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Quotes from CONF_iture:

"Actually the CVR transcript is clear :
"Thrust SRS ! RUNWAY" at time 12 40 59"

Yes, so we'll have to hope that my recollection of 25 years ago is better than that of what I read 25 hours ago! Thanks, I've amended my post.

"Anomalous I agree, as the call should have been either MAN FLX or MAN TOGA, but if no flex temp had been previously entered, and Asseline had set the thrust levers to the FLX detent, the ECAM ENG THR LEVERS NOT SET would have been triggered ... Was it different in 88 ?"

Yes, it was certainly different on the A320 in 1988 (I'm not au-fait with current A320 FMAs, which may or may not have changed). Your "MAN FLX" and "MAN TOGA" were simply "FLX nn" and "TOGA". In the absence of an assumed temperature in the FMGS (as inevitable on a touch and go), and the throttle levers at FLX/MCT, the FMA would indicate "THR". I don't recall any associated ECAM mesage, but am not sure. IIRC, the FADEC would deliver TOGA in that configuration, but it would seem sensible to advance the throttles to make sure. I've yet to find any reference to this situation in my contemporary FCOMs.
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