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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 5th Jan 2012, 07:46
  #1061 (permalink)  
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If two ADR outputs are erroneous, but different, and the remaining ADR is correct
- now that's a software challenge! How does a computer work that out?
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Old 5th Jan 2012, 09:17
  #1062 (permalink)  
 
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Caygill

Do you mean "official and so trustworthy" ?
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Old 5th Jan 2012, 11:04
  #1063 (permalink)  

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"...now that's a software challenge! How does a computer work that out?"

Look at the preceding ten minutes and decide which set of data is the most sensible and likely.

If the anaesthetised patient has been cruising along with a blood-pressure of 120/80 for the last hour and monitor A suddenly shows 60/20, while monitor B continues to show 120/80 then monitor A is likely to be wrong.

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Old 5th Jan 2012, 13:05
  #1064 (permalink)  
 
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I apologize if this has already been sent here: Air France Catastrophe: Victims' Families Propose Grounding All A330s - SPIEGEL ONLINE - News - International

A Strange Anomaly
The Hanover legal practice of Ulrich von Jeinsen, which composed the letter, and the Berlin aviation law expert Elmar Geimulla made mention in the letter that there could be "criminal consequences" should indications of a software error not be thoroughly investigated and another Airbus crashes for the same reason.
Von Jeinsen's motion is primarily based on the expert opinion of Gerhard Hüttig, a professor at the Institute of Aeronautics and Astronautics at the Technical University in Berlin. Just over a year ago, Hüttig recreated the Air France crash in a flight simulator. In the course of the exercise, Hüttig noticed a strange anomaly in the plane's reaction once it goes into a stall. The trimmable horizontal stabilizer, a flap instrumental in keeping the plane on an even keel, automatically adjusted to push the nose of the plane skyward.
Hüttig, a former Airbus pilot himself, and other pilots present for the test were unable to push the nose of the airplane down and thereby escape the stall.
When the BEA released its preliminary report last Friday, Hüttig immediately zeroed in on data relating to the trimmable horizontal stabilizer. During the final minutes of flight AF 447 as it plunged toward the Atlantic, the flap moved from a 3 degree deflection to a 13 degree deflection, almost the maximum possible. "The phenomenon is startlingly similar," he told SPIEGEL.

A Quiet Reaction
Hüttig passed along his simulator findings to Airbus, the European Aviation Safety Agency (EASA) and to BEA. On Oct. 27, 2010, Hüttig received a response from EASA which said that Hüttig's theory was inconsistent with the "current state of knowledge." "We suspect that the anomaly you found originated with the simulator you used in the study rather than with the airplane model A330," the response read.
Hüttig and Jeinsen told SPIEGEL that the data recovered from the wreck of flight AF 447 would now seem to have corroborated the simulator findings. Furthermore, Airbus has quietly reacted to the safety loophole. In a communiqué to airlines, Airbus provided a new version of pilot instructions for dealing with a stall. Furthermore, in the January issue of its internal safety magazine, there is a mention of manually trimming the horizontal stabilizers.
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Old 5th Jan 2012, 16:00
  #1065 (permalink)  
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Only blip there, Mac, is that if you look at the PGF Airbus accident, 2 of the 3 ADRs were giving apparently 'normal' readings (having frozen in the cruise) while the third was giving correct and significant readings and warnings but all 3 were 'shut-off' by the logic. There's your software dilemma. Presumably some nice little nurse comes along in your scenario and ideally makes a logical assumption, but in mine along she comes to find all three readings blank.
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Old 5th Jan 2012, 17:13
  #1066 (permalink)  
 
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englishman,
The article was initially posted here in June 2011.
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Old 5th Jan 2012, 17:28
  #1067 (permalink)  
 
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It's somewhat interesting to note that Hüttig claims that no-one present at this simulation was able to get the nose down, while the data shows Bonin applied nose-up inputs almost throughout the accident sequence, which is Airbus' defense against the claim. And this latter info is what we here have essentially subscribed to, as if there was no other earthly possibility.

And yet, and YET.....Pprune posters still insist that the recorded inputs are either incompetent or inexplicable. I am still suspicious of this point.

To recap other info that's been presented here: it's been also said that there is no way to reproduce this stall in a simulator, since there's no air data from testing for such. Just trying to save us a few more rotations of the hamster wheel.

Last edited by Organfreak; 5th Jan 2012 at 17:29. Reason: lame spelling
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Old 5th Jan 2012, 17:34
  #1068 (permalink)  
 
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@BOAC.

"A// If two ADR outputs are erroneous, but different, and the remaining ADR is correct, or if B// all three are erroneous, but different"


Ref A//. equals Ref B//.


You can not leave this to software (software programmers uses the same human logica,
but humans can add parameters - on the fly - to make a more proper selection.
The reason this NAV ADR DISAGREE and associated drill, is presented to the
crew is to prevent software of outvoting the only GOOD source (if any).

If "2 of the 3 ADRs were giving apparently 'normal' readings" as you stated, this NAV ADR DISAGREE
message would not have been presented on the ECAM!

@Mac the Knife:

10 minutes is 'ages' in flight, so much can change in so little time,
10s is nearly the max. to look back as reference.

For FCPC ADR voting principle see Page 54/55 in BEA Interim #1.






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Old 5th Jan 2012, 18:30
  #1069 (permalink)  
 
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If the anaesthetised patient has been cruising along with a blood-pressure of 120/80 for the last hour and monitor A suddenly shows 60/20, while monitor B continues to show 120/80 then monitor A is likely to be wrong.
This actually happened to me (sort off), anaesthetised patient
(me) suddenly showed 0/0 which was correct & needed immediate intervention. Suppose monitor A had got stuck
at that moment. My training in electronics is a bit out of date,
but in my day "stuck at" was a problem which needed a bit of
attention.
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Old 16th Jan 2012, 22:01
  #1070 (permalink)  
 
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Angel the flying rudder

@Mr Bloggs
"Vertical Taiplane Separation"
for instance, see my post in Techlog forum, Thread AF447 N°7, post #729 December 23. 2012. I am waiting a full analysis from the BEA, and not only "NO,NO,NO !".

That is not a conspiracy ; that is a question in the query
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Old 17th Jan 2012, 00:06
  #1071 (permalink)  
 
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@roulishollandais:

The evidence is in the BEA interim report #2:

The VS was salvaged with the HST jackscrew upper attachments frames 86/87,
The jackscrew itself was located on the site.
Parts of the HST (which fractured on impact) where located in some distance from the site.

If the VS separated in flight there was no structure to take the HST loads anymore and the HST including jackscrew would have been separated too.
Besides that there would have been a load of messages containing Rudder, Elevator and Trim failures and the rear control surfaces FDR traces would not have been recorded until the end.





Structure part in green.
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Old 17th Jan 2012, 00:46
  #1072 (permalink)  
 
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Besides that there would have been a load of messages containing Rudder, Elevator and Trim failures and the rear control surfaces FDR traces would not have been recorded until the end.
Yes, and there would have been hydraulic failures as well. Didn't happen.
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Old 18th Jan 2012, 16:44
  #1073 (permalink)  
 
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Snoop

Thank you for your comments, A33Zab and MachinBird

Last edited by roulishollandais; 22nd Jan 2012 at 19:43. Reason: spelling Machinbird
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Old 18th Jan 2012, 21:54
  #1074 (permalink)  
 
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Have you seen this?

A330 Pilot Speaks Out - AF447
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Old 18th Jan 2012, 22:14
  #1075 (permalink)  
 
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Been posted many times and is quite frankly rubbish.
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Old 18th Jan 2012, 23:06
  #1076 (permalink)  
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Actually in my opinion not rubbish

Quite a bit of sense there. I'm not going into the A vesus B thing, because I can't be bothered - I've flown both (multiple) types.

However I would add that 'real experience' (despite the type they were flying) would have helped them to overcome the situation they found themselves in.

The originator of the article (A330 Pilot speaks out) excuses the Pilots explaining how the Airbus can lead one to disaster. He is right in some ways in that the Airbus phiosophy can lead to pilots to ignore basic facts (aerodynamic if you like).

These Pilots (or the Pilot in the RH seat) ignored basic pitch cues and flew the aircraft into the water.

That is a fact however you want to stitch it up. The Pilot (or Pilots) ignored the high pitch indication and stalled into the water.

I find it hard to forgive Airbus (or Boeing for that matter) for allowing a stall indication to stop because the the A/C IAS has decreased below a certain amount.



Occams razor here I think.
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Old 19th Jan 2012, 02:21
  #1077 (permalink)  
 
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I find it hard to forgive Airbus (or Boeing for that matter) for allowing a stall indication to stop because the the A/C IAS has decreased below a certain amount.
No real arguments about your post until the sentence quoted above. The manufacturers A or B do NOT expect properly trained commercial pilots to HOLD an A/C into a FULLY developed stall. Especially having given them all the warnings prior to the stall, which you were also alluding to in your comments. So we cannot really blame the manufacturers.

It was not just because the IAS went below 60Kts but the AOA was also outside limits. Flight testing into the fully developed stall is not carried out so they do not know how the interrupted airflow would affect the various readings.

Hamster wheel again!
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Old 19th Jan 2012, 04:58
  #1078 (permalink)  
 
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The manufacturers A or B do NOT expect properly trained commercial pilots to HOLD an A/C into a FULLY developed stall
Despite all the training and all alarms announcing the stall .. manufacturers now know (and I think they knew it before the case of AF447) it is possible that pilots hold an aircraft in a fully developed stall
What will be their proposals to remedy this ... if any .. and so break this hamster wheel ..
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Old 19th Jan 2012, 10:02
  #1079 (permalink)  
 
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There has to be a trade off between safety features and system complexity and with this a certain level of pilot competence is expected. Probabilities feature largely in how systems are designed and what protections are required

Having said that, if the type of deep stall that has occurred here can render the normal stall warning useless due to airspeed < 60kts, would it not be possible to derive a warning from a combination of high rate of descent / Vertical speed together with a high nose up attitude above a pre-determined or abnormal value?

Its possible that incidences of deep stall do not justify this change to the normal warning / protections.
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Old 19th Jan 2012, 10:23
  #1080 (permalink)  
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Now write the software loop to handle possible erroneous vertical speed signals and/or attitudes? It does not get easier with 'automatics'. You may well find you will create another 'trap'.
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