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Habsheim

Old 25th Jan 2014, 13:55
  #381 (permalink)  
 
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Originally Posted by HN39
The DFDR does not generate a 'time' parameter as such.
Yes it does, the CVR doesn't.
Where does the labelled GMT H MN on the Habsheim listing come from then ?

Nothing is recorded 'continuously' on a DFDR.
If the DFDR is able to restitute every second and confirm them every 4 seconds, that's pretty 'continuous' to me.


Originally Posted by NeoFit
I didn't know that one, but it seems to be a pretty good resume on the Justice side ...
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Old 25th Jan 2014, 14:18
  #382 (permalink)  
 
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Originally Posted by CONF iture View Post
Where does the labelled GMT H MN on the Habsheim listing come from then ?
He already told you:

Originally Posted by HazelNuts39 View Post
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.
Regarding the blog post, not only does it get significant allegations wrong (translated):

Monday, June 27, all authorities will conclude the innocence of the accident airplane charging multiple pilot errors.
We've already established that the report does not conclude pilot error to be the only factor, and I've explained that it would be practically impossible for anyone to have manipulated the data. Plus the fact that the only extraction employed and performed by the CEV was a direct dump to paper hard copy indicates there was no intermediate process where data could have been changed (at least not without being glaringly obvious to the naked eye).

The latter, under the pressure of complaints by passengers and the Union of Airline Pilots (SNPL) will handle the case in an emergency such as law requires.
There's those four letters again - they can throw around as many allegations about the judicial handling of the case as they like, but it doesn't prove malfeasance on the judicial side and it certainly doesn't have any bearing on the technical investigation.

Last edited by DozyWannabe; 25th Jan 2014 at 14:37.
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Old 25th Jan 2014, 14:25
  #383 (permalink)  
 
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Hi DW,
The report states that engine behaviour was normal,
If we all agree on the end of recording (impact) at time 339 seconds, then is there any point about discussing when the recording started?

If you look at data on TOME 4, at time 240 secs, the engine N1s (1,2 %)follow the TL positions (Manettes 1,2 DA (angle)). As the TLs are closed (+014 to -0), the engine revs decay slowly from 68% to about 30% - which appears normal.

Between time 328 to 330, the TLs are advanced to the GA position (+45) and the engine revs increase from 29% to 83% by time 334.
The TLs are then closed briefly (-0) at time 336, and then advanced to +25 position at time 338. Meanwhile the engine revs decay from 83% to 56% then back to 86/87% - then end of recording.

It appears that the engines did respond normally (they achieved 83% within 4 to 6 seconds of moving the TLs from idle), but Capt. Asseline thought they had not and briefly closed them seconds before impact.
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Old 25th Jan 2014, 14:42
  #384 (permalink)  
 
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Originally Posted by rudderrudderrat View Post
Between time 328 to 330, the TLs are advanced to the GA position (+45) and the engine revs increase from 29% to 83% by time 334.
The TLs are then closed briefly (-0) at time 336, and then advanced to +25 position at time 338. Meanwhile the engine revs decay from 83% to 56% then back to 86/87% - then end of recording.

It appears that the engines did respond normally (they achieved 83% within 4 to 6 seconds of moving the TLs from idle), but Capt. Asseline thought they had not and briefly closed them seconds before impact.
Interesting. Am I right in thinking that procedure of going back to the idle detent and thence forward to climb or TOGA only really applied to situations where A/THR is active? If so, it might indicate a last-ditch reversion to trained behaviour on the part of the Captain, even though A/THR was supposed to be disengaged?
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Old 25th Jan 2014, 14:57
  #385 (permalink)  
 
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That reduction to 56% certainly wasn't going to help matters in front of the trees; it would also have set the computers an unusual - if not difficult - task, to hold the aircraft stable close to maximum AoA as the power cycled up, half- way down and then up again.

I wonder if that power reduction about 5 seconds before impact agrees with the much-discussed-on-documentaries sound recording timing from the crowd's video? Perhaps the conspiracy-minded are hearing and timing the second rise in N1 just before impact with the trees, when in fact they should be timing the first rise in N1 after which the throttles were cycled. I remember "5s" is always quoted as the claimed engine delay.

I also wonder whether the perceived lack of apparent response from the engines that led to Asseline cycling the power levers was reinforced by odd cues from being lower and slower than expected?
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Old 25th Jan 2014, 15:08
  #386 (permalink)  
 
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Hi DW,
Am I right in thinking that procedure of going back to the idle detent and thence forward to climb or TOGA only really applied to situations where A/THR is active?
If you select TOGA, you should get TOGA power irrespective of whether the A/T is engaged or not.
It appears to me, that had he maintained the TLs in the TOGA position, then he would have had TOGA thrust by time 335 (engines accelerate very quickly at high power settings).
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Old 25th Jan 2014, 15:13
  #387 (permalink)  
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Hi rrr,

"If we all agree on the end of recording (impact) at time 339 seconds, ..."

Afraid not... HN39 and I have discussed this at some length. The last time frame whose data is totally uncorrupted is TGEN 334.0, and is treated, IIRC, as t-zero in the reports.

During TGEN 335.0, the data start to unhinge. That, following what appear to be uncorrupted signs of the initial impact, is particularly noticeable in the 4 sequential values of x and y accelerations (longitudinal and lateral respectively), and the 8 values of z (normal) acceleration presented in Tome 3. In Tome 1, the single sample of GS glitches to 648 kt.

Last edited by Chris Scott; 25th Jan 2014 at 15:45. Reason: Typo. Last para expanded.
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Old 25th Jan 2014, 16:07
  #388 (permalink)  
 
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Originally Posted by Chris Scott View Post
The last time frame whose data is totally uncorrupted is TGEN 334.0, and is treated, IIRC, as t-zero in the reports.

During TGEN 335.0, the data start to unhinge. That, following what appear to be uncorrupted signs of the initial impact, is particularly noticeable in the 4 sequential values of x and y accelerations (longitudinal and lateral respectively), and the 8 values of z (normal) acceleration presented in Tome 3. In Tome 1, the single sample of GS glitches to 648 kt.
Just to be clear, this should not be seen as anything particularly untoward in terms of process. As it turned out, the Loral-branded F800 DFDRs fitted to early A320s had issues with data corruption when subjected to shocks over a given threshold:

G-KMAM Incident

The DFDR was a Loral F800. This type of recorder has been found to give poor performance on the A320, and the investigators discovered that the DFDRs on all four of Excalibur's A320s had a history of problems, including random track changing, incorrect Built-In Test Equipment (BITE) indications, and corruption of data (AAIB 2/95 Sections 1.11 and 2.11). The track changing and BITE problems were cured by the replacement of a certain Electrically Erasable Programmable Read Only Memory (EEPROM) unit, a modification which Loral made mandatory only in response to considerable pressure from industry and regulatory agencies.

The data corruption appeared to be due to vibration. The anti-vibration tray on the A320 had not been tested to the requirements of Radio Technical Commission for Aeronautics (RTCA) document DO-160 "Environmental Conditions and Test Procedures for Airborne Equipment". Trials after the incident showed that the recording quality was improved by mounting the DFDR on a tray conforming to the DO-160 standard.

(AAIB 2/95 specifies the DFDR as "Loral F800". The DFDR on F-GFKC which crashed at Habsheim in 1988 was referred to as a "Fairchild F800" and that on F-GGED which crashed at Strasbourg in 1992 as a "LORAL-Fairchild F800" in the appropriate reports. Presumably these are all references to the same make and model of DFDR.)

Since 1989, Airbus Industrie have used a different make of recorder for all test and certification flights. It is stated (AAIB 2/95 Section 1.11, p 17) that the Loral recorder is fitted only on delivery to the customer. Precisely what the status of the airworthiness certificate is following this modification is not clear!
A320 Spoiler Disconnection

Investigation of this revealed that this was a common problem and that although Airbus had made a number of approaches to Loral regarding the unit, the situation had not improved.
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Old 25th Jan 2014, 16:13
  #389 (permalink)  
 
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Originally Posted by RRR
The TLs are then closed briefly (-0) at time 336, and then advanced to +25 position at time 338.
Originally Posted by Dozy
Interesting
Originally Posted by awblain
That reduction to 56% certainly wasn't going to help matters in front of the trees
And all at 10 46 GMT when the crash was at 12 45 ...
You are all very confused, and the BEA made sure you would be with such a 'pitiful' report.
Never wonder why the English version was not on the BEA site ... ?
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Old 25th Jan 2014, 16:32
  #390 (permalink)  
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Gentlemen,

Although the DFDR itself has the advantage of being in a protective compartment at the tail of the a/c, the scores of sensors that supply the data to it, not to mention the FDIU/FDAU itself, are not afforded that luxury. They wouldn't be much use if they were...
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Old 25th Jan 2014, 16:37
  #391 (permalink)  
 
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Hi Chris,
The last time frame whose data is totally uncorrupted is TGEN 334.0, and is treated, IIRC, as t-zero in the reports.
Thanks for the correction.
In which case, Capt. Asseline didn't select TOGA until sometime after 328 and before 330.
That was only 4 to 6 seconds before impact with the tree tops, and the engines had accelerated to 83% & 84%.

Edit: I don't see what was unusual about the engines response.


Last edited by rudderrudderrat; 25th Jan 2014 at 19:19.
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Old 25th Jan 2014, 17:41
  #392 (permalink)  
 
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Originally Posted by CONF iture View Post
You are misinformed
Am I? How convenient
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Old 26th Jan 2014, 15:41
  #393 (permalink)  
 
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@ CONF, post 383

If the crew questioned the aircraft functioning BEFORE their presentation at Habsheim, they have been even more stupid to start such an unusual flight, very close to the limits of any operation particularly with passengers on board!
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Old 26th Jan 2014, 19:50
  #394 (permalink)  
 
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@ Bidule, post 398

It is not forbidden to read the thread first.
Habsheim #312

Last edited by CONF iture; 26th Jan 2014 at 22:58.
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Old 27th Jan 2014, 01:04
  #395 (permalink)  
 
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@CONF:

The BEA aren't hiding the earlier (known) malfunction, it simply isn't relevant to the incident. They are hiding nothing else. People who are still tilting at windmills, like yourself and your chums at the SNPL however, are very much on a hiding to nothing if this thread is anything to go by.
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Old 27th Jan 2014, 02:34
  #396 (permalink)  
 
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Originally Posted by dozy
They are hiding nothing else.
Not even the English version of the report or the annexe VII ... but why am I asking that to a guy who even don't know the CONF setting used in Habsheim but cannot stop commenting on things he simply has no knowledge on ... !?
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Old 27th Jan 2014, 16:06
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Originally Posted by CONF iture View Post
Not even the English version of the report or the annexe VII ...
If you use the report search facility on the BEA's website, you'll note that even today the BEA do not routinely publish a report in a language other than French unless one of the major parties involved comes from - or unless the accident itself occurred - outside of France. No "hiding" there.

Annexe VII covers the period directly concerning the accident only - it was, and in many cases still is, standard practice for most agencies to do this. Any data from other phases of the flight is quoted in short form during the narrative section of the report - again, nothing "hidden" and nothing untoward.


but why am I asking that to a guy who even don't know the CONF setting used in Habsheim but cannot stop commenting on things he simply has no knowledge on ... !?
I was tempted to report your post for this unnecessary personal swipe, but haven't done so as I don't want to seem petty.

For what its worth I've deliberately restricted my input to the computer systems design and specification as much as possible - any comment of mine outside of those bounds only refers to aspects that can be understood with a little basic aero knowledge plus a decent level of reading comprehension (or explicitly quotes people with the requisite qualification when responding to them).

Far more qualified minds than mine have been picking apart the technical and piloting aspects - not to mention the operations angle in which, as the BEA correctly stated in their report, AF are deservedly found significantly wanting (I found gums' sense of disbelief very appropriate on that point). You've got A320 line pilots both current and former - as well as at least one A320 TRE - saying that the aircraft behaviour seems normal.

From my point of view, and I've said this before, I take back my initial reservations about going over this again because I've learned a whole new raft of information for which I am very grateful. I came into this new discussion ready to defend my existing position that the BEA report was fit for purpose and the aircraft's behaviour expected, but prepared to be open to change that opinion if evidence showed otherwise - I have to say that the new or clarified information uncovered has tended to strengthen that opinion (for what little my opinion is worth) rather than undermine it.

As far as the non-technical aspects of the aftermath go, it seems to me that it was the parties acting for Capt. Asseline and the union who showed more interest in pursuing a predetermined agenda than the judiciary, Airbus or the BEA. Of the latter three parties, it is the BEA who in retrospect come across as by far the most even-handed, going to considerable lengths to take evidence, both primary and secondary (from all parties) into consideration when trying to determine what happened. The oft-repeated myths that the authorities sought to solely blame the flight crew, ignored allegations made by Asseline and the SNPL and tampered with flight data simply do not stand up to scrutiny when even a cursory review of the evidence is undertaken.

I do have some sympathy for Capt. Asseline, because while his judgement skills regarding conduct of the flight undoubtedly fell short of the standards required, he and his flight crew were poorly prepared and briefed by the airline prior to the flight (and the airline subsequently had no qualms about using a contradictory rule regarding minimum altitude for display flights to throw him under the bus). Not only that, but as Chris Scott suggests, I'm beginning to think he was poorly advised by those representing him - leading him away from what may have been a reasonable argument against the airline and instead convincing him to pursue allegations of technical failure against the manufacturer, a much more difficult proposition legally, but more in keeping with their long-held desire to score points against Airbus.

That it can be inferred such advice was given to an undoubtedly traumatised man wrestling with his own sense of responsiblity - of which a natural psychological factor is denial - does little to endear them in my opinion.

Last edited by DozyWannabe; 27th Jan 2014 at 16:23.
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Old 27th Jan 2014, 16:26
  #398 (permalink)  
 
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@ CONF

It had been read but as you again went this way, the repetition seems to be useful!
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Old 27th Jan 2014, 20:40
  #399 (permalink)  
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Quote from Linktrained (January 13th):
"The flight had been briefed to be at 100 ft along R/W 34 L.
Perhaps due to the realignment with grass R/W 34 R the aircraft used some of its potential energy (now only height and airspeed, with flight idle having been set at 12.44.14) the descent to 46 ft became inevitable. This required more of a climb than hadbeen planned - or an earlier selection of TOGA by a few seconds ( 10 ?)."

Sorry to respond so late. First, perhaps it's worth reminding ourselves and others again that the fly-past was ill-conceived by the airline, with no provision made for a recce-flight or a ground inspection, and minimal preparation by both the airline and the crew. The notion of making an approach with a load of commercial passengers to a platform of 100ft QFE on an unknown non-runway (in A320 terms) - followed by a level-off, during which the a/c would be decelerated to within a couple of degrees of the stall AoA; followed by a high-alpha go-around - must rate as one of the most irresponsible in public-transport ops since the flying circuses of the 1920s and 30s.

Once committed, there would be little room for even one technical failure or significant crew-misjudgement. This crew seems to have made at least three serious errors in the execution of the briefed game-plan.

(1) The a/c arrived at the airfield boundary with far too much energy - kinetic and potential - to achieve the briefed game-plan of establishing stable flight at high AoA, using thrust to maintain speed in level flight during the transit of the airfield.

(2) The a/c levelled off at an indicated barometric height of about 60 ft above the reference altitude of the airfield - on both the pilots’ altimeters. (This assumes they had been correctly set to the QFE of 984 hPa, as announced in the CVR transcript). During the next 14 seconds before first impact, the barometric height fell slightly to about 50 ft, finally recovering to about 60 ft. Allowing for pressure-altimeter tolerances, together with the forward position of the static-pressure port and the aircraft’s high pitch-attitude, as much as 20 feet could be subtracted from the above values to “guess-timate” the actual heights.
It seems clear that, however foolish the airline and the captain were to plan the flypast at 100 ft on the QFE, the a/c would in all probability have cleared the trees had it been flown thus.

(3) The go-around was initiated too late to achieve any significant climb before the tree line was reached. In the event, insufficient time was allowed for the certificated time of engine acceleration from idle thrust, and the a/c was carrying a negligible surplus of kinetic energy to convert to any increase in altitude.
Prior to selecting TOGA thrust, the crew may have neither been aware of the horizontal distance to the tree line; nor the fact that the engine nacelles, landing-gear, and rear fuselage were lower than the tree tops. Their opportunities to recognise the hazard of the trees may have been limited: due initially to the rushed approach, and later to the visibility restrictions of the high pitch-attitude.
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Old 27th Jan 2014, 21:47
  #400 (permalink)  
 
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Is it usual to see such mistakes punished by nine months firm jail?
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