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AF 447 Thread No. 8

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AF 447 Thread No. 8

Old 4th Jul 2012, 21:53
  #1541 (permalink)  
 
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Originally Posted by clandestino
If you happen to be referring to other A33o/340 UAS events, then: nope. We don't know that yet.
I think jcjeant is referring to the Air Caraibes memo, where the main issue is that their pilots considered the occurrence of (legitimate) stall warnings to be "inappropriate" and wanted to justify their decision to ignore the phrase in the Airbus UAS procedure which says: "respect stall warning and disregard RISK OF UNDUE STALL WARNING status message if displayed on ECAM".

Last edited by HazelNuts39; 4th Jul 2012 at 22:12.
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Old 4th Jul 2012, 22:13
  #1542 (permalink)  
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From the Daily Telegaph (an apalling rag in my opinion)

Air France crash 'caused by pilot error'
It then goes on to say:
A French report has found that human error contributed to the 2009 crash of an Air France flight from Rio to Paris

Contributed or caused? What appalling journalism.

I have my own ideas which are in line with many contributers to this thread however I find the headline from this rag says more about the newspaper than the Pilots.
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Old 5th Jul 2012, 00:09
  #1543 (permalink)  
 
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Clandestino
I think that the original questioner, months ago, was really asking if "there were any ordinary civilian training aircraft with S/S controls?"

I would guess that you (or even I) might be able to define ordinary, without recourse to Law. That probably rules out the F-16D on cost grounds as well.
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Old 5th Jul 2012, 00:21
  #1544 (permalink)  
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if "there were any ordinary civilian training aircraft with S/S controls?"

..
at the risk of being consigned to the Fires of Hell for my impertinent comment, I don't suppose you would consider the Victa AirTourer's fly by (thick) wire side stick as qualifying ? Not only can the other pilot see the controller's position and movement, he/she can grab a hold of it as required.
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Old 5th Jul 2012, 00:53
  #1545 (permalink)  
 
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Smile John

At last... an answer... Thanks !
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Old 5th Jul 2012, 05:02
  #1546 (permalink)  
 
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Thanks to Hazelnuts recently passing a link to the engauge digitizing software, I have finally been able to perform roll behavior analysis on the initial movements of AF447. Admitted that this is the 11th hour and 59th minute before BEA releases their report, but the evidence is very strong that the crew encountered a roll PIO that took their full attention away from the proper control of their aircraft and concentrated their attention on the roll problem to the detriment of the big picture.

I was able to digitize the roll angle to a high degree of accuracy and then calculate the roll rate on a short interval basis. The roll rate data was then smoothed by a moving average technique. The result is as follows:



From this, it can be seen that the peak roll rates exceeded 10 degrees per second. This roll rate in an oscillation would not be ignored by a pilot and he would be unable to "look through" it to the larger picture.

We had a substantial discussion at the time I put forth the possibility of a roll PIO and rather than re-post that discussion, I will merely provide a link to that portion of thread number 7.
http://www.pprune.org/tech-log/46839...no-7-a-35.html

There are ~5 different potential causes for PIO. BEA has not yet provided spoiler and aileron position data, so analysis of the causal aspect is not yet possible.
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Old 5th Jul 2012, 06:46
  #1547 (permalink)  
 
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Thanks for the pointing towards Air Caraibe memo

It seems that initially, not just the pilots but also the safety pilot of Air Caraibe believed that stall warnings were undue. Is there full report on the incident? While the crew might have believed stall warning was false, it is obvious they kept AoA under control.

Originally Posted by lyman
I think that the original questioner, months ago, was really asking if "there were any ordinary civilian training aircraft with S/S controls?"
Cirrus SR20. We don't have ordinary civilian training aircraft with FBW and independent sidesticks because it would be far too expensive to retrofit something like C172 with hydraulic powered controls, air data computers, inertial reference and top it up with FBW electronics.

Originally Posted by Machinbird
From this, it can be seen that the peak roll rates exceeded 10 degrees per second. This roll rate in an oscillation would not be ignored by a pilot and he would be unable to "look through" it to the larger picture.
Nice picture. Could you, pretty please, extend it 30 seconds further?

Originally Posted by Machinbird
BEA has not yet provided spoiler and aileron position data, so analysis of the causal aspect is not yet possible.
Well, if it doesn't make it to the final report, you can always use page 112 of interim 3: lateral DFDR parameters. Ailerons and spoilers staunchly followed the sidesticks, their periods of fluttering like mad were occasionally interrupted by full LWD deflection with not much apparent effect, as expected in stall.
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Old 5th Jul 2012, 07:22
  #1548 (permalink)  
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Clandestino;

I haven't found a "full report" on the Air Caraibe event. I don't think there is one.

Links to the original (French). The English translation has been unavailable for some time. This link takes you to an English version/discussion of the memo. It is close but not exactly the one I was able to retrieve a while back.

Been thinking about this respect the stall warning/ignore the stall warning matter....

The UAS QRH Drill / Checklist (dated Dec 01/08) states,

Technical recommendations:
Respect Stall Warning, and disregard the “RISK OF UNDUE STALL WARNING” STATUS message, if displayed on ECAM.
– To monitor speed, refer to IRS Ground Speed, or GPS Ground Speed variations.

If remaining altitude indication is unreliable:
– Do not use FPV and/or V/S, which are affected.
– ATC altitude is affected. Notify the ATC.
– Refer to GPS altitude: altitude variations may be used to control level flight, and is an altitude cue.
– Refer to Radio Altimeter

The "Risk of Undue Stall Warn" message occurs on the STATUS page of the NAV ADR DISAGREE ECAM Checklist and occurs not on the ECAM page but on the STATUS page as an advisory message after everything else is sorted out. Here's what it says:

____________________________________________________________ __STATUS

– MAX SPEED ..............................330/.82______________|NOP SYS
_______________________________________________|____________ __|RUD TRV LIM
____________________________________________________________ | |CAT 3 DUAL


APPR PROC :
– FOR LDG ........................................ USE FLAP 3
This line is replaced by “FOR LDG : USE FLAP 3” when CONF 3 is
selected, as a reminder.
– LDG DIST PROC ...................................APPLY
Refer to the QRH 2.TOC.
CAT 3 SINGLE ONLY
RISK OF UNDUE STALL WARN
Undue stall warnings may mainly occur, in case of an AOA discrepancy.
RUD WITH CARE ABV 160 KT
The rudder travel limit value is frozen at the moment when the failure occurs.
Therefore, to prevent damage to the aircraft structure, use the rudder with care, when the speed is above 160 knots. At slats' extension, full rudder travel authority is recovered

The two messages shouldn't really be confused because the "Undue...etc" message is not seen on the ECAM until the correct ECAM SOPs have been completed for the NAV ADR ECAM.

The UAS Drill / Checklist and accompanying QRH notes is clear - Respect the stall warning.

The messages aren't contradictory but they can be made to appear so taken out of the operational context as I think the website to which I point, above, has.

That doesn't mean that it is not possible to confuse this! I think it is if one isn't paying attention. They're two different circumstances.

I frankly doubt if they had any training either way regarding whether to "respect the stall warning" or not. At the point they were at in the event that's pretty subtle stuff to be sorting out in the middle of all that was going on particularly the increasing anxiety.

If there were suggestions floating around that they may have picked up through discussion with other crews that "the stall warning could be false" and it "should" be ignored, that's a training, competency and cockpit discipline issue, not an ECAM/QRH issue I think. The message on every UAS drill I have is to respect the stall warning. We'll see what the report says, anyway...

PJ2

Last edited by PJ2; 5th Jul 2012 at 09:01.
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Old 5th Jul 2012, 09:47
  #1549 (permalink)  
 
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respecting stall warnings

PJ2
If there were suggestions floating around that they may have picked up through discussion with other crews that "the stall warning could be false" and it
"should" be ignored, that's a training, competency and cockpit discipline issue, not an ECAM/QRH issue I think. The message on every UAS drill I have
is to respect the stall warning. We'll see what the report says, anyway...


A procedural question from a non-pilot.

I assume that a stall warning requires a prompt response, while an event such as UAS requires a more considered response [and resort to a checklist].

If so, shouldn't the initial response to a stall warning be a memory item? With any caveats about ignoring stall warnings being part of that memory item.

This way there would be no place for confusion about when to ignore stall warnings. In particular, in-depth study of specific checklists in isolation would
not risk confounding the issue. Even when the checklists themselves may be context-specific and/or ambiguously worded.

Regards, Peter
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Old 5th Jul 2012, 09:52
  #1550 (permalink)  
 
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Clandestino

Thank you for your many replies, pointing me, ultimately, to the Cirrus SR20. I expect that may be helpful to the original correspondent ( if I can find him !) More comfortable than the Dart Kitten or the Slingsby Motor Tutor in the winter, too.

LT
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Old 5th Jul 2012, 10:05
  #1551 (permalink)  
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Thread #9 starts here.
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