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AF 447 Thread No. 7

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AF 447 Thread No. 7

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Old 7th Nov 2011, 09:42
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AF 447 Thread No. 7

AF 447 Thread No. 7

Thread part -

(a) #1 starts here and finishes here. Posts = 3890
(b) #2 starts here and finishes here. Posts = 2537
(c) #3 starts here and finishes here. Posts = 2071
(d) #4 starts here and finishes here. Posts = 1061
(e) #5 starts here and finishes here. Posts = 1978
(f) #6 starts here and finishes here. Posts = 1683


Links to the various BEA reports are given below. If I have missed any of the useful papers, please PM me with the URL and I can include it.

(a) BEA site - French, English
- Report link page - French, English

(b) Interim Report (No, 1) Jul 2, 2009 - English

(b) Interim Report No. 2 Dec 17, 2009 - English
- Update Dec 17, 2009 - French, English

(c) Estimating the wreckage location Jun 30, 2010

(d) Wreckage search analysis Jan 20, 2011

(e) Briefing and associated update May 27, 2011
- Briefing - update French
- Briefing - update English
- Briefing - update German
- Briefing - update Portugese

(f) Interim Report No. 3 July 2011 - French, English

Miscellaneous pertinent links -

(a) Airbus Operations Golden Rules
(b) ALPA FBW Primer
(c) C* and Civil Transports - Cranfield
(d) Longitudinal Flight Control Design - RAeS
(e) Longitudinal Stability: Effect of High Altitude and CG - Boeing
(f) pitot static system performance - USN (Pax River) FTM
(g) The Problem of Automation: Inappropriate Feedback and Interaction, Not Over-Automation. Donald A. Norman UCSD
(h) Upset Recovery - 16MB zip file
(i) Ironies of Automation. Lisanne Bainbridge UCL
(j) Cognitive Capability of Humans. Christopher Wickens Uni Illinois
(k) Trust in Automation: Designing for Appropriate Reliance John D. Lee, Katrina A. See; Human Factors, Vol. 46, 2004
(l) Training for New Technology. John Bent - Cathay Neil Krey's CRM site


Search hint: You can search PPRuNe threads with a filter in Google by using the following search string example -

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Adding the site:URL end part is the magic that restricts Google to only searching in Tech Log.

This filter technique is absolutely wonderful and can be used generically to find things of interest in PPRuNe - appears to work OK in the PPRuNe search function as well.

In respect of Google searching, JenCluse has added some suggestions -

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Old 7th Nov 2011, 10:35
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DozyWannabe, thanks for your last post (#1681) in the previous topic.

One question about it: you didn't mention thrust settings during your tests.
What were they? Did you change them during the simulated flights?
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Old 7th Nov 2011, 12:26
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On searching for text strings in this long discussion, via Goog

Mr Tullamarine:

May I suggest thet your suggestion ref searching, with it's example text, be modified slightly?

I's suggest that the generic entry "ths af447 site:http://www.pprune.org/tech-log/" be modified slightly, by:

a) indenting that text block with a (one) Tab, *and*

b) emphasizing the fact that it is a search text block with some manner of . . .
<SearchText>, or
"SearchText", or
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I'm sure you get the picture :-?
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Old 7th Nov 2011, 15:40
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Thanks for the thanks folks. For convenience, I'll link to my original "weekend sim research" post here:

http://www.pprune.org/tech-log/46062...ml#post6793521

@xcitation - Having conferred, we loaded extra fuel so that the FMGC showed MAX ALT FL379. C of G was 32% MAC. The ROD in our experiments maxed at approx 6,000ft per minute, with the VSI needle turning amber in the PFD. One of the reasons I hope someone will perform a later experiment will be to see how leaving the recovery till later in the sequence will affect the ROD, and hopefully also find out how a 40% MAC CoG will affect things. The caveat here is that the later you leave it, the further outside the tested flight envelope you go, and the more divergent the sim's performance from the real thing will become.

@AZR - Initially, autothrust dropped to Thrust Lock. We pulled the thrust levers back to match the thrust, but as we moved them the thrust increased slightly. The TRE then deliberately staggered the TLs slightly to induce a roll to the right which we trimmed out with rudder and the slightest touch of aileron.

After the initial NU pitch increase (induced with approximately half back-stick, as in the DFDR traces), we triggered a very short "G" induced stall warning as we climbed, then when the real warning sounded continuously (as happened in the AF447 scenario) we applied TOGA and held 10 to 15 degs pitch on the sidestick - during which full deflection was required in order to come close to maintaining it - as I said, the nose wanted to come down naturally if I released pressure for even a split-second.

Hope this helps!

Further details I've just been reminded of - the stall stabilised at approx 180kts IAS on the sim control with the nose-up trim at 3 degrees (the A320 hard limit). With full nose-up trim the stall was similar, but stabilised at approx. 160kts IAS. The Stall Warning was not only clear, but so loud that the TRE had to cancel it with the Emergency Cancel button in order for us to hear each other. On the second (full nose-up trim) experiment, all I had to do was briefly glance down to my left to see the trim roll forward - smoothly and *very* quickly - following recovery via sidestick pitch down.

Last edited by DozyWannabe; 7th Nov 2011 at 16:08.
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Old 7th Nov 2011, 16:39
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DW: Thanks
Originally Posted by DozyWannabe View Post
(...)we applied TOGA and held 10 to 15 degs pitch on the sidestick - during which full deflection was required in order to come close to maintaining it - as I said, the nose wanted to come down naturally if I released pressure for even a split-second.

Hope this helps!
OK, I understand you never did (or had to) go idle to get the nose down. That's reassuring.
Now, does that apply :
- on an A330 sim
- on a real A320
- on a real A330

?
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Old 7th Nov 2011, 16:51
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No problem. As for your question, I suspect there will only be minor differences - but the short answer from my end is - that's for other people to find out.
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Old 7th Nov 2011, 16:52
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Don't under-estimate the sim.

My boss, the famous RD, said to me: "you can learn a lot about the aircraft in the sim".

True, I'm telling you.
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Old 7th Nov 2011, 17:41
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Possibly if a poster might provide pictures of an A320 and an A330, we could verify by looking at them that they have similar stall characteristics.
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Old 7th Nov 2011, 18:02
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The purpose of the experiments was not to provide any definitive data on stall characteristics, they were simply a technical exercise to determine if there were any obvious system problems or design deficiencies that would make recovery difficult, which it would appear there are not. We can say that with a significant degree of confidence for the A320 and a reasonable degree of confidence for the A330, as the systems designs for both share common parentage in terms of flight control requirements.

Aerodynamics is not my specialty and I'll defer to those who know better, but if I were to make an educated guess, given that a lot of the same people were involved in the airframe developement of the A320 and her larger sisters, I'd say it's a reasonable assumption to make that they are fairly docile in stall characteristics across the range. The TRE's opinion was that the A320 seems extremely docile in the stall if the sim behaviour was anything to go by - and this guy seemed to know what he was talking about - appearing to be a pilot's pilot of the old school through and through, with types from every pretty much every major manufacturer of the last 40 years under his belt.
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Old 7th Nov 2011, 19:03
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Dozy,
Good on you for an interesting experiment.

I gather you didn't get to a high enough AOA to experience the invalid airspeed condition (or that the sim was not programed to duplicate that feature). One wonders how the little 'Bus would handle that.
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Old 7th Nov 2011, 19:31
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Originally Posted by Machinbird View Post
I gather you didn't get to a high enough AOA to experience the invalid airspeed condition (or that the sim was not programed to duplicate that feature). One wonders how the little 'Bus would handle that.
The sim is not programmed to handle that (as I understand it's it's a little-understood phenomenon to start with), and even if it did we didn't have enough time to take it that far outside the envelope while I was there. My testing colleague ran them to a greater degree the week before and said that the sim outputs relayed valid speeds (despite the failed air data situation relayed to the PFDs and flight control logic) all the way down, or at least as far down as they went. Just to be clear, this test was simply intended to demonstrate that nothing was untoward with the systems, there was no unintended knock-on effect from Alternate Law affecting the controls and that even with full nose-up trim wound in it should be possible to effect a recovery with sidestick input alone *as long as the situation is recognised in a timely manner*.

Last edited by DozyWannabe; 7th Nov 2011 at 19:42.
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Old 7th Nov 2011, 19:48
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One more test which confirms once more that aircraft or its systems are not to blame (if we forget that there still had the problem for a short blockage of pitot tubes) in the minutes that followed the withdrawal of the auto pilot and power levers
The plane is once again not to blame .. it's work perfect
Everything converges again to the way pilots reacted to the event
If they react well .. results will be likely those of the tests
We know that was not the case
So .. stay on the playing field:
Pilots
Air France
Regulation offices (DGAC .. BEA ... etc..)
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Old 7th Nov 2011, 22:43
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DW, does the sim produce a lot of noise when “stalled” and held in the stall with high RoD?

(It was reported in an earlier thread that somebody who had heard the CVR said that the air rush noise in the AF447 cockpit was very loud, and may have added to the PF confusion by reinforcing any belief he might have had that their problem was overspeed, as that too would have been noisy; and the pilots had probably never heard either noise before in the aircraft, and may not have heard both in the sims.)
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Old 7th Nov 2011, 23:36
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Not particularly, there was a noticeable increase in volume and we were getting bumped about a fair bit - but I can tell you that in that simulator the stall warning was LOUD when it activated, certainly loud enough to get my attention even with the headset off. The only way to compare relative volume would be on the CAM track of the CVR. Hopefully the CAM and HOT sources will be made clear in the transcription of the final report.
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Old 8th Nov 2011, 02:24
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Originally Posted by dnrobson
Vertical Speed = 10,000 fpm, How can one not realise one is stalled?
It is more complex than that.
With full back stick, the PF managed to silent the STALL warning and to temporarily obtain a V/S between zero and -2500ft/min (it is not clear which V/S is recorded ...)
Of course both PNFs have no idea what are the inputs of the PF for that time.
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Old 8th Nov 2011, 02:32
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Originally Posted by DozyWannabe
CONF - the final report on this accident is still some time from completion, give them a chance. Having said that, given the number of ambulance-chasing vultures that would attempt to twist the data to suit their commercial ends, I'm not surprised that the release of data is limited.
Vultures won't fly much on twisted data.
Find something else.
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Old 8th Nov 2011, 08:40
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DW in the sim:
-I'd suspected it would involve considerable effort to hold the sidestick there for a significant amount of time, but I was genuinely surprised at just how much.

-The Stall Warning was not only clear, but so loud that the TRE had to cancel it with the Emergency Cancel button in order for us to hear each other.
never say never,

your first comment show that with a bit adrenalin in your hand the spring in the SS is not so strong as expected from the designers, and this can play surely a role for the beginn of AF447s zoom climb

the second one..... if this cancel button would exist also in a real A330, IŽd say they would have pressed it for the same reason.......
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Old 8th Nov 2011, 11:30
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your first comment show that with a bit adrenalin in your hand the spring in the SS is not so strong as expected from the designers, and this can play surely a role for the beginn of AF447s zoom climb
Dozy's saying that it was even stronger than he'd expected...
the second one..... if this cancel button would exist also in a real A330, IŽd say they would have pressed it for the same reason.......
It does. And it would be clearly evident on the CVR, wouldn't it?
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Old 8th Nov 2011, 15:05
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grity:

Zorin_75 is right - it was *more* difficult (schwierig oder schwer - nicht leichter) than I expected to hold the sidestick all the way back. And the EMER CANC button is on the A330, in the same place on the ECAM panel - I've highlighted it here in yellow for you.

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Old 8th Nov 2011, 16:25
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well, I have to ask for pardon, for my mistranslation
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