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AF 447 Thread No. 8

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AF 447 Thread No. 8

Old 18th Apr 2012, 01:18
  #81 (permalink)  
 
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Hi PJ2

The TITANIC was unsinkable, but for an un-designed for event (clogged Pitots?), the way she struck the iceberg.

She was built of a horizontally stacking series of watertight compartments. But she struck the berg tangentially, a glancing blow. So she acquired a long gash in her hull, the first seven compartments communicating with the sea. A head on would have smushed her to three/four compartments back, and she would have remained on the surface.

Tragically, she should have been steered into the iceberg, not away. She sank to the bottom of the Atlantic, 12,500 feet down. At 2am, her Captain was called back to the bridge, (familiar?). He was too late, and could not have helped.

Hubris, Sir, indeed. Boasting at Nature's door, not advised, eh?

Take care,
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Old 18th Apr 2012, 18:43
  #82 (permalink)  
 
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Oh dear.

I think it's time to officially add Dozy's addendum to Godwin's Law here, namely:

"As a PPRuNe discussion involving Airbus continues, the probability of someone bringing up Habsheim and concierges approaches 1."
This may sound a little presumptuous of me, but I think I can get away with saying that Habsheim is not relevant to this incident or this discussion. Feel free to PM me if you want to know why. Regarding Ziegler and his oft-quoted "concierge" remark, he didn't say anything about his concierge being able to fly it in a degraded control mode or damaged state, so can we please leave that tangent there?

As it happens I'd be willing to go to the mat and bore for England on the subject of Titanic as well, but again it really isn't relevant to the case we're discussing.

It's pretty clear to me that until new information is released, this subject has been discussed to a standstill.
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Old 18th Apr 2012, 19:18
  #83 (permalink)  
 
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Tex Johnson actually rolled one, and managed not to put it into the trees.

Chutzpah, claiming an addendum to one's own petard.
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Old 18th Apr 2012, 19:34
  #84 (permalink)  
 
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I don't follow.

Johnson planned and executed an unauthorised addition to a flightplan he otherwise stuck to like glue, but nevertheless had planned that addition in secret and went in knowing exactly what he was doing. Asseline got lost (not his fault) missed his TOD waypoint, tried to fudge his descent profile to catch up and ended up in the trees. Equally importantly, Johnson was not carrying passengers.

Quite what this has to do with AF447 is beyond me.
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Old 18th Apr 2012, 21:50
  #85 (permalink)  
 
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Airbus, Flight Plan, Boeing, Display flight.

Wheat/Chaff

I think both were demo flights, wait, I know they were. Airbus needs to stop promoting to chief pilot or even F/O, those who lose the plot, in cahoots with the platform/Format. Funny how many nincompoops get into the front dere, yes?

Are you trying to tell me Airbus doesn't have a glossy release prepped at a moment's notice to exonerate the a/c for any foul/up? In at least one case, the manufacturer applied pressure to have the investigative body carry their d'Eau, No? Pre Paris Air Show? Fetes d'avions? Nothing wrong here, nope.

If Airbus wasn't addicted to excuse making, they might release all the data they own? IOW, the whole deal, they got off BEA? By that I mean, if they are innocent, what is behind the white knuckles holding on to 447's data?

Goes to motive, and intent.

Everything Airbus has done since 1988 pertains to 447. Didn't auto/recover from CFIT result from Asseline's folly? Not all bad, then? Weren't they attempting to get their arms around "Unreliable Speeds" when the 330 went down? At some point, it might be nice to admit a problem, take a breath, (PARK THEM), and not fly until the problem can be sussed and mitigated?

Mon Dieu! Je ne sais pas! Moment, s'il vous plait.
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Old 18th Apr 2012, 22:51
  #86 (permalink)  
 
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[Quoting in full in case the original post "disappears"... Apologies.]

Originally Posted by Lyman View Post
Airbus, Flight Plan, Boeing, Display flight.
Wheat/Chaff
I think both were demo flights, wait, I know they were. Airbus needs to stop promoting to chief pilot or even F/O, those who lose the plot, in cahoots with the platform/Format. Funny how many nincompoops get into the front dere, yes?

Are you trying to tell me Airbus doesn't have a glossy release prepped at a moment's notice to exonerate the a/c for any foul/up? In at least one case, the manufacturer applied pressure to have the investigative body carry their d'Eau, No? Pre Paris Air Show? Fetes d'avions? Nothing wrong here, nope.

If Airbus wasn't addicted to excuse making, they might release all the data they own? IOW, the whole deal, they got off BEA? By that I mean, if they are innocent, what is behind the white knuckles holding on to 447's data?

Goes to motive, and intent.

Everything Airbus has done since 1988 pertains to 447. Didn't auto/recover from CFIT result from Asseline's folly? Not all bad, then? Weren't they attempting to get their arms around "Unreliable Speeds" when the 330 went down? At some point, it might be nice to admit a problem, take a breath, (PARK THEM), and not fly until the problem can be sussed and mitigated?

Mon Dieu! Je ne sais pas! Moment, s'il vous plait.
Forgive me if I'm appearing dense here, but it appears to me that despite the fact that you're using mostly English words, and your sentence structure is largely OK, I can discern no coherent meaning from that post at all.

If I sort of squint and angle my head slightly, however, it would appear that you've just tried to imply a conspiracy between Airbus and French authorities to absolve Airbus of any problems with their products and to blame pilots when things do go wrong - a conspiracy that is ongoing and goes back to 1988.

If that is indeed what you're saying, then you've basically confirmed what I've suspected for about a year now - that your continued posting of ever more bizarre theories, alternating with assurances of good intent, were nothing more than a smokescreen - behind which lurked merely another person who bashes Airbus because they never got over Habsheim.

To which all I can say is : Even Captain Asseline is over *$!?%&g Habsheim by now!

To answer your "points" (after which if you want to talk about this it does not belong in the AF447 thread) :
  • Both were demonstration flights, but AF296 was carrying passengers because it was due to continue from Habsheim to a sightseeing flight over Mont Blanc. The Dash-8 barrel roll would never have been considered under those circumstances. The decision for the former lay with AF ops, not Airbus - the latter lay with the test pilot alone (AF447 : No relevance)
  • Capt. Asseline was an AF training captain, *not* an Airbus employee (AF447 : No relevance)
  • *Every* airframe manufacturer will, in the absence of an obvious design problem, try to prove their product is not at fault - think Boeing and the 737 rudder PCU issue (AF447 : No relevance)
  • The decisions as to how much data is to be released, when, and to whom are based on relevance and made by the investigating authority, not the manufacturer. No investigation bureau in the world has ever released full, unexpurgated FDR traces, and yet you conclude that because the BEA is doing the same, they or Airbus must be hiding something. Paranoid much?
  • The pitot tube replacement work was scheduled at the airlines' discretion, not Airbus's. In the meantime Airbus met due diligence criteria and published a procedure to be followed in case of UAS, which was not followed by this crew
  • An AD grounding the fleet would have been overkill in this instance, because procedures were established to deal with the problem without incurring additional risk - just like the increased approach speed numbers to counteract the 737 rudder hard-over fault in the late '90s

I dread to think how many hours I've spent patiently explaining documented facts that refute the claims of skulduggery between the BEA and Airbus either then or now, so I'm not going to repeat myself further.

I'm glad you've finally revealed your true colours Lyman. I'd like to say it's a weight off my mind, but frankly I've barely given this any thought of late - and will not be doing so until more information is forthcoming.
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Old 19th Apr 2012, 09:47
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Recovery trajectories

I'm sympathetic to Dozy's pov that missing new data the subject has been done to death, but we need not expect to see any new factual data ex BEA since their "cartoons" already give much more information than is customary in accident reporting. The data has, after all, been enough to keep these threads going for a year or so!

OTOH, with HN39's help (but any errors are mine!) I have been able to construct a means of calculating performance at and beyond the stall, and this in turn allows a systematic study of recovery possibilities - something that AFAIK has not been presented here before, so perhaps it qualifies as "new data"?

On the diagram, the yellow line is the actual AF447 flight path derived from BEA traces of inertial ground speed and barometric altitude, corrected for wind effects wherever possible.

The purple line is a theoretical calculation of that flight path using the developed method with actual flight pitch and power (N1) as input data. Given the fact that the aircraft was gyrating with six degrees of freedom and the model is restricted to three, I think it a reasonable match which gives some credence to any recovery calculations. Others may differ.



Wherever you see a red line the stall warning was, or would be, operative.
The blue bits on the recovery trajectories are the final pull ups.
All recoveries assume 104% N1 throughout.

The interesting finding for me was that it is not necessary to go to extreme nose down attitudes to recover - in fact it may even be counterproductive, since although you arrive at a good 'flying' speed at a higher altitude, you have further to go in pitch and if you do that at a moderate rate the extra time uses up all the benefit. Countering that by a more aggressive pitch up rate looks as if it may get you into secondary stall territory.

The other point is that the actual rate of pitch down at entry into the recovery is not all that important either. If you are going to be in a 10 deg ND dive for 60 seconds it really makes little difference if it takes you a few seconds more or less to get there.
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Old 19th Apr 2012, 13:55
  #88 (permalink)  
 
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Originally Posted by PJ2
No, there almost certainly isn't.
And you are most certainly correct, not in the FDR, in the QAR most probably but the chance we are informed some data were retrieved from the QAR would be that those data can further advance the main idea behind that last piece of mind formatting :


Still, the AP/FD vertical engagement mode trace must be one from the FDR. I am concerned we have not seen it yet, like I was concerned we have never seen the vertical acceleration trace for Perpignan ...

Originally Posted by Old Carthusian
Some prefer the yoke but remember the yoke will not necessarily guarantee safety. Given that this is the case then one cannot criticize the side stick on the grounds it is less safe. One can say I prefer the yoke because it has this factor which is important for me but that is all.
Sidesticks suppress information of GREAT value for a PNF Did it play a role for AF447 ? I think it did.

Originally Posted by Owain Glyndwr
The interesting finding for me was that it is not necessary to go to extreme nose down attitudes to recover
It depends at which AoA the recovery process is engaged. At 40 degrees of AoA anything short of 30 degrees of negative pitch is useless. Airline pilots are not trained to command such negative pitch especially at a time when minimum altitude loss was the most important credo.
In the meantime I must admit your graph is a bit complex for me.
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Old 19th Apr 2012, 15:17
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ACARS: Excellent system. It worked, brilliantly.

Two way Comms: FAIL

UAS drill: FAIL

RADAR sytem: FAULT

Engines: Excellent

INTERFACE FAIL

PITOT PROBES: FAIL

Coincidence? A a=system designed solely to make money, to minimize gear down time, and streamline operational reliability, performs flawlessly. Had they arrived, the work would have begun at chocks in.

Is this a commentary on priorities? Yes.

UAS drill? Any pilot who cannot keep current with instant P/Power values, and be ready with gentle and decisive handling, needs to be back at ops, in the sim. Even DOZY can get a sim ride, AF is too cheap to add a drill of 7 minutes to the syllabus?

If it continues, perhaps we should address an upgrade to the way we fish parts and bodies out the SEA........

I have one word for the designers: PROACTIVE
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Old 19th Apr 2012, 15:29
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Very interesting graph Owain Glyndwr. It appears that at lower altitudes, the nose down control is much more effective and thus the pitch down to flying AOA occurs much more quickly.

What assumptions are made in this graph regarding nose down trim performance by the flight control system? What assumptions are made with regard to AOA management by the crew since the flight control system does not manage AOA in Alt law.

They could have still recovered down to ~5000 feet if all went perfectly? What a tragedy.
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Old 19th Apr 2012, 15:33
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Dozy got a sim ride through an act of incredible kindness on the part of three people he will always be eternally grateful to (one in particular).

Dozy managed to perform a manual takeoff first time, followed the FD around, recovered the aircraft from the AF447 scenario *twice* and managed a successful FD-led landing on the second attempt (having fumbled the throttle/stick co-ordination on the first). Dozy did all that in around an hour and a half. Dozy hadn't been anywhere near the controls of an aircraft since he last got out of an AEF Chippie in 1993.

How you can say there's anything wrong with an interface that allows a clumsy doofus like Dozy to manage that I cannot fathom.
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Old 19th Apr 2012, 15:49
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Doze. If you expect to be taken seriously, you will have to be serious. It is outrageous that you should compare your jaunt with a certificated long haul ATPL.

OWAIN. The graph is beautiful, but I too am having some difficulties. Could you take us through some of the data? For instance you have a G demarcation that looks luscious, but can you give some direction as to how it may have felt, indexed with a/s, and ROD?

many thanks.

DOZY: "Followed the FD around...." There's a ripe apple, can you elaborate?
Is that something an ATPL in 447 land might do?
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Old 19th Apr 2012, 16:00
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Machinbird

What assumptions are made in this graph regarding nose down trim performance by the flight control system? What assumptions are made with regard to AOA management by the crew since the flight control system does not manage AOA in Alt law.
None - it is just a performance calculation in which the crew is assumed to apply pitch at a given rate until the desired steady ND value is achieved, and then to fly constant pitch attitude until about 250 kts EAS at which point it is assumed that pitch is reversed at the same rate as going in, unless the S/W boundary is exceeded in which case the pitch rate was backed off to keep inside the limit (this only applied in the 3 deg/sec FL350 case). There is an implicit assumption that since the crew did not have AoA information they couldn't fly to manage it, but they could fly pitch.

Don't look for too much detail in this picture - it isn't there.

They could have still recovered down to ~5000 feet if all went perfectly? What a tragedy
Yes, but can you see anyone passing through FL60 at 10,000 fpm applying 10 deg ND pitch and holding it? This line unfortunately is very theoretical.

Lyman

For instance you have a G demarcation that looks luscious, but can you give some direction as to how it may have felt, indexed with a/s, and ROD?
Since there is no G on the graph I am at a loss how to reply, but the pull-up 'g's were in the range 1.4~1.7

Last edited by Owain Glyndwr; 19th Apr 2012 at 16:05. Reason: additional comment
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Old 19th Apr 2012, 16:02
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I'm not comparing anything, I know full well that controlling the aircraft is merely the base level of what you can achieve. An ATPL would have to do a lot more. However, "following the FD" is *exactly* what the AF447 pilots had been trained to expect to do 99% of the time.

The reason I was able to recover (aside from the complex psychology behind me knowing I was in a sim and them knowing they weren't and that their lives were on the line) was the fact that I knew what was coming and how to recover, whereas it would appear that they did not. I had about 5-10 minutes following the FD on a departure orbit to get a feel for the thing before the scenario was loaded and I got dropped in the doo-doo.

That wasn't me blowing my trumpet by the way, that was me saying that the Airbus cockpit ergonomics are in fact very good. So good that even I could acquit myself with minimal egg on my face.

There was no radar "fault" either - the radar's exactly the same as in any other airliner of that vintage.
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Old 19th Apr 2012, 16:25
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Originally Posted by DozyWannabe View Post
How you can say there's anything wrong with an interface that allows a clumsy doofus like Dozy to manage that I cannot fathom.
Your day job wouldn't be concierge by any chance... ?
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Old 19th Apr 2012, 16:45
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Cool

Hi,

Owain Glyndwr
The data has, after all, been enough to keep these threads going for a year or so!
Can be also ...
The lack of data has, after all, been enough to keep these threads going for a year or so!
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Old 19th Apr 2012, 18:09
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O.G.:

I'm curious about your Mach lines vs CAS vs altitude.

For example, your chart shows Mach 0.8 at 30,000 is 288 CAS.

I get 304 CAS for Mach 0.8 at 30,000.

In addition, I show A330 Va reaches about 315 KCAS at 27,000 where it intersects the Mach 0.78 Va limit for the aircraft.

You have 0.78 Mach intersecting Va at about 290 KCAS.



(Is it an ISA + x thing?)

Last edited by OK465; 19th Apr 2012 at 18:20. Reason: ISA question
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Old 19th Apr 2012, 18:11
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Originally Posted by Owain Glyndwr
Yes, but can you see anyone passing through FL60 at 10,000 fpm applying 10 deg ND pitch and holding it?
No way 10 degrees ND was enough to go anywhere, be it at 5000, 20000, or 35000 feet on the way down when the AoA was already above 30 degrees.
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Old 19th Apr 2012, 20:58
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OK465

I'm curious about your Mach lines vs CAS vs altitude.

......
(Is it an ISA + x thing?)
No, it's a senior moment. I picked up the wrong values from the spreadsheet. The Mach lines shown are EAS not CAS. doesn't change the other numbers though which are all CAS - these Mach lines were just for background info. Thanks for the correction.

Last edited by Owain Glyndwr; 19th Apr 2012 at 21:12.
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Old 19th Apr 2012, 21:52
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Originally Posted by infrequentflyer789 View Post
Your day job wouldn't be concierge by any chance... ?
No mate, way above my pay grade.
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