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AF 447 Thread No. 7

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AF 447 Thread No. 7

Old 1st Apr 2012, 00:52
  #1161 (permalink)  
 
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Salute!

I gotta go with Roul ( newbie on this thread best I can tell) and RR.

I can not claim 20,000 hours ( mostly cruising at 35K and monitoring the autopilot, and taking a break now and then to the bathroom or whatever). I will match my 4,000 hours against anyone here. Except for the ocean crossings, I rarely flew much autopilot except to find a let down chart or something that I had not prepared for. Oh yeah, every two or three hours crossing the ocean I had to snuggle up to a tanker at about 30 or 40 feet away and get some gas. BFD except in a thunderstorm or at night.

The human interface is extremely important. The basic pilot skills are extremely important. If the robots were really good and had some judgement, then I would be O.K. with them. But they are not.

Somehow we have lost a sense of airmanship. It's as much a skill as an attitude. The new planes are more like a video game than an old plane that required touch and feel and basic flying skills. I flew all kinds. The big thing I learned was that basic flying skills counted more than all the computer assistance and such when things turned to worms.

I shall go with Doze and others' opinions that had the pilot just let the plane alone for several seconds, that we would not have this thread or the fatalities. Many contributing factors and design aspects here. We shall see.

I shall not absolve the crew's actions.

But I cut them a little slack due to the Airbus reversion mode sequence and some confusing warning indications. I also submit that the 'bus FBW system is not as "safe" as all the PR implies.

Gotta go....

Gums
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Old 1st Apr 2012, 00:57
  #1162 (permalink)  
 
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Why?

Hi,

Anthropologist, Bear:

Man is the only sentient being who predictably misses that which is obvious.

Why?

Mac

Last edited by RR_NDB; 3rd Apr 2012 at 04:37.
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Old 1st Apr 2012, 01:38
  #1163 (permalink)  
 
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Cool

Hi,

RR-NDB
Since the beginning BEA told the equipt. worked as designed.
I hope you noticed that in the other cases (B747-B737) the equipt worked as designed (bad design of course) .. and it was "apocalypse"
Working as designed is not a proof that the end result will be good
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Old 1st Apr 2012, 01:52
  #1164 (permalink)  
 
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roulishollandais,

I think one has to be realistic when citing percentages. The gold standard is Six-Sigma - 99.99966% free of defects. You can calculate what this might mean in terms of successful flight hours. However, I should point out this does not include the thing that nature might throw at you, variables that are beyond any control. When you take into account the machine and all of its various component makeup, the human factor and all that could and does imply, and the nature of flying in an atmosphere that can be and is unpredictable at best, Six-Sigma can be a goal, an admirable goal, but may take considerable time to reach, if at all obtainable. Think of all that must happen to make it so. However, the human aspect can overcome some of the shortcomings of the other two variables, as has been pointed out by various pilots, based on proper training, proper instincts and hands on learned abilities...

TD
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Old 1st Apr 2012, 01:56
  #1165 (permalink)  
 
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Hi,

gums

The basic pilot skills are extremely important.
Rich data base, Intrinsic creativity enhanceable by adrenalin.

Nothing compares.

The big thing I learned was that basic flying skills counted more than all the computer assistance and such when things turned to worms.
In "normal conditions" automated Systems are designed to work near perfection. Who can perform so good during long hours "yaw dampening"? And performing as an autopilot? Just impossible.

When "worms are in sight" the System MUST HELP. This is ABSOLUTELY necessary in a good design (and relates DIRECTLY with the "interface")

It's inconceivable one need to interpret when facing difficult conditions "what the plane is telling" through unreliable, massive, erratic or intermittent indications of it's machine to man, interface.

PR (and sales people) concentrates on the "beauties" of new designs. What we know (in real world) is another face. Every mechanism has limitations.

In AF447 case during this fascinating and rich effort a large group of motivated professionals in a high Synergy addressed most aspects involved, here in PPRuNe.

Certainly HF aspects (closely related to the "interface") will be the "key" to explain crew actions that sadly put the A/C in a "terminal state" in a "near terminal speed".

Mac

PS

I also submit that the 'bus FBW system is not as "safe" as all the PR implies.
May be we could put like:

Airbus SAS approach is not what PR implies. Generating (clearly generated this even in pilots) a perception of something less dependent on "crew skill" than other approaches.

IMHO it's the opposite: In order to be able to interpret (and act) when the 'worms are in sight" the 40 seconds PJ2 mentioned could be too long.

In terms of this loss of control, while it unfolded literally over a period of about 40 seconds, oddly that is tons of time to do something, but it is not a lot of time for assessment, discussion, action.
The "capable pilot" here makes the difference.

Yes, we shall see. We don't have all required information. We need to wait to conclude.

Every judgment before (all relevant factual information) is at least, risky.
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Old 1st Apr 2012, 01:57
  #1166 (permalink)  
 
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PJ2 NeoFit came up with 3300 feet to recover the a/c from full STALL (SL).

The 7400' was elsewhere, Did we not see the video? Full Stall to safe landing in camera.

jcjeant, In Construction, it is called "As Built", or "After the Fact". Also, there is Design/Build, which is too sloppy for Airbus. It worked well enough for Clarence Johnson,

RR_NDB. Because sometimes Humans prefer "Correct" over "True". "Correct" requires a tacit wink/nod, though, and falls short of 100% SAFE. Culture requires compromise, and sometimes compromise is deadly. For instance, I ask three questions, and get an answer for one unasked, ignoring the valid three.

In the scheme of things, all here are safe, for now, and should consider thinking of some scary things, instead of reassuring each other. Ignorance is not bliss, it is merely ignorance. And faux comfort.
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Old 1st Apr 2012, 02:20
  #1167 (permalink)  
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The gold standard is Six-Sigma - 99.99966% free of defects.

Indeed, but 6σ applies to the folk who step back a pace and contemplate the population.

For the individual on the day, the reality is more binary ... either you are in strife or not. From the perspective of standards, either the system accepts the population risk as acceptable (and the occasional mishap as inevitable) or provides some semblance of training (admittedly at a cost) to give the individual some reasonable hope of employing the cognitive things which humans are good at.

Like PJ2, I hold the view that a bit of sim time for crew exposure to the improbable may (not necessarily will) provide some benefits.
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Old 1st Apr 2012, 02:59
  #1168 (permalink)  
 
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Hi John,

In a way, that is what I was trying to say, but maybe wasn't clear enough. Indeed, training can/does help overcome the realities presented that are not normal.

Thanks and regards,

TD
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Old 1st Apr 2012, 03:00
  #1169 (permalink)  
 
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COS, near Honolulu and climbing out JFK cases

Hi,

jcjeant,

1) 737 PCU malfunction: Only after Colo. Spgs crash ("testability problem") they started to detect a hidden problem. i don't know if we can classify this as a "design problem". Far more subtle than the Pitot's problem.

2) 741 Flight 811: Indeed a design fault with MANY incidents before this case.

3) 741 TWA 800: IMO doesn't fit as a design problem.They improved the design reducing the risk of a similar case.

Mac

We need to be cautious dealing with "design problem" classification. Everything could fit in that category. E.g. "lack of redundancy is a Design Problem? Not necessarily.

The use of Redundant OBSOLETE sensors (triple redundancy) that "FAILS" near simultaneously IMO is a SERIOUS DESIGN PROBLEM. The use of just one PCU (737) compared to the (redundant) 727 IMO is not a Design Problem. And in the 737 the lack of redundancy magnified the (hidden) problem.

The first case (COS 35 final) was shocking. The plane just rolled diving vertically from ~ 1,000 ft AGL when in the final. I can't imagine the feeling of both crew. Gusty winds masked the analysis. And it was a subtle (not easily testable) problem. Few days before the crash there was "strange" behavior involving rudder. Intermittent failure in a "closed loop" System.

Testability is a complex issue. For some problems only TIME can test.

Last edited by RR_NDB; 1st Apr 2012 at 03:34. Reason: Text impvmt
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Old 1st Apr 2012, 03:15
  #1170 (permalink)  
 
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Awareness increase

Hi,

john_tullamarine:

At least could help to emphasize what can happen. I think, worth the effort. For some. Not necessarily all.

Mac
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Old 1st Apr 2012, 04:07
  #1171 (permalink)  
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I can't imagine the feeling of both crew.

But now contemplate the situation had a crew either in flight experience or sim exposure to something similar.

Might they have been able to bring that experience to bear in time, for instance, to try asymmetric thrust as a counter in combination with aileron input ?

An effective initial solution doesn't always have to be elegant ... but it may need to be implemented very quickly without too much Monday morning quarterbacking if it is to have any real world probability of working ...
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Old 1st Apr 2012, 04:19
  #1172 (permalink)  
 
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John T.

I don't think we can fairly or even logically reject that there were ad hoc and unusual attempts made at recovery. The panel here would have none of it, in general, but let's not forget Bonin, (RHS, PF) was a licensed Glider pilot, as was Sully. I have always been impressed with the rating, for obvious reasons.

We'll see. Or not. I have been unwilling to make the leap I believe necessary to simply assume that an experienced Glider pilot would be so thick in PITCH.

Energy.
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Old 1st Apr 2012, 04:36
  #1173 (permalink)  
 
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99.99966% free of defects
I have no idea to what this applies

certainly not to individual parts like screws, pistons, solonoids, switches and jeezuz bolts.

Maybe with a good quality control program and sampling you might get 75%, but an awful lot of stuff on planes rarely gets the sampling to even validate the quality control.

The idea to achieve safety is to provide backup, like redundancy, alternate paths and trained pilots. That way it takes a lot of things going wrong to result in a catastrophic outcome (death and destruction)

again my belief is opposite a lawyer's

"if not for"


and instead I would still insist on

"in spite of"

as the way to achieve safety in a complex machine of multiple systems called an airplane etc.
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Old 1st Apr 2012, 05:00
  #1174 (permalink)  
 
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Yaw versus roll

Salute!

The Colorado Springs disaster was, indeed, sad. Also lost another jet of the same type near Pittsburgh if I am not mistaken. The stoopid rudder actuator would stick and only a determined effort punching the pedals could offer any hope of recovery. Sad, sad, sad.

(flew into the Springs and out last week and that crash was on my mind)

Folks here that have never flown a swept wing to the edge of the envelope and beyond may not appreciate how important yaw control is. "Retired" can tell all about that when flying the Phantom - lock stick between legs and only use rudder to roll the sucker to counter adverse yaw, and the jet is shaking and the buffet is very severe. Didn't have that problem in the Deuce due to basic aero characteristics of a delta, nor in the Viper- aero and flight control systems much better in the late 70's and 80's.

I side with PJ and RR for the most part. Training and the human interface are two factors that must be addressed by the 'bus folks and the BEA report. I will take PJ's experience in the type over anybody else here. I will take my own experience in 5 or 6 jets over anyone else here, as well.

late here in Florida, and gotta go.

Gums
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Old 1st Apr 2012, 06:40
  #1175 (permalink)  
 
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Originally Posted by roulishollandais
The final loss of height is not your 22000 FT, nor FL200, nor 15000 FT,
but 5000 (max) +(FL100-FL76)=7400 FT
Dutchroll, these were speculative numbers for a last minute escape from the full stall. The pullout is dependent on achieving near maximum performance, and the stall recovery altitude/time is entirely speculative. The emphasis should be on speculative. Remember, this is for near maximum performance. Without an AOA indicator, I see no way to come close to these numbers. OK465 seems to believe it will be a problem teaching people when and if to add some power during pullout to improve performance. He is probably correct.

My intent in coming up with these speculative pullout figures is to remind people who may be in similar situations to not give up! You might think you are toast, but keep thinking and keep flying to the limits of your ability. You just might get a pleasant reward. The light at the end of the tunnel is not always a train.

PJ2s post #1107 (http://www.pprune.org/7109943-post1107.html) is the result of a number of simulator runs of the AF447 scenario and involved a high altitude initiation of the recovery. This is essentially valid data within the unknowns of how well the Sim matches reality in an area it isn't really certified for. Perhaps PJ2 can tell us something about the power setting during the recovery. (High power would be a worse recovery condition than idle power.)

If the recovery is initiated lower, it is likely that the pitch rates nose down will be higher, the descent rates a little lower, and thus the time/altitude loss to unstall the wing may be somewhat less.

Just like the Viper has a sticky spot in its pitching moment curve, the A330 may also have a sticky spot. There may be techniques for achieving a higher nose down pitch rate, but it is not worth risking a test crew to find them. With proper fixing of the myriad Swiss cheese holes that led to AF447, we should never see a similar incident involving an airliner during my lifetime (and I plan on living a long time).
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Old 1st Apr 2012, 08:31
  #1176 (permalink)  
 
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I rather think we need to be very careful in talking about 'deteriorating skills' because of increased automation. A cursuory examination of past accidents will show many, many examples of where piloting skills were lacking and these on unautomated aircraft where piloting skills were required. Automation has improved aircraft safety immeasurably. Several 'solutions' have been suggested on this thread but all run up against issues. Changing the technology is neither easy nor necessarily desirable. It must be realised that this is a human caused accident and removing the pilot would have probably been the only way to have avoided this accident. Remember the adage 'We keep on making things foolproof but God keeps on designing better fools'. I will state again - no matter how well you design a system someone will find a way to evade it and wreck it in a totally unexpected way. That is the reality of this accident.
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Old 1st Apr 2012, 09:33
  #1177 (permalink)  
 
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Why did the crew not maintain 85% thrust and 5 degrees pitch up to maintain a safe speed?
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Old 1st Apr 2012, 16:06
  #1178 (permalink)  
 
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Why did the crew not maintain 85% thrust and 5 degrees pitch up to maintain a safe speed?
T-Vasis
That is the $64,000 question. There are two basic lines of thought on this.
  1. They mis-applied UAS procedures applicable to lower altitudes.
  2. They were distracted by a roll PIO to such an extent that they lost track of what was happening with the aircraft.
We are all hoping that BEA's Human Factors experts can figure this out with some clarity.
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Old 1st Apr 2012, 16:24
  #1179 (permalink)  
 
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3. It is not known the condition of the pilots' displays. The Data divulged on this thread is from a source unavailable to the crew during their ordeal.

4.From the awkward interaction between the two (then three) pilots, some problem can be taken re: at least the Flying Pilot's displays (screens).

5. There is no conclusion re: some interesting observations made by the pilots themselves: "What was that?" "I feel some crazy speed"....etc. "ER....What are you doing?"....et al.


6. Additionally, these noises and artifacts are not released as found, and given the BEA make no comment with exposure of their evidence, the conclusions here are completely unsupported.

7. With his very first input, the Pilot was greeted with a STALLWARN, cricket, sufficient one would think to start a cascade of confusion from a cascade of data, some important, some less so, some completely unnecessary.

It is quite possible that 5 degrees NU was completely insufficient, and without knowing the data supplied to the crew, the "book" may have been worse than the reality.

It is painfully clear that the situation was challenging, despite the protest of those who believe it was just another night at the office.

Hopefully, and with a complete record, more will be known. It is possible what the pilots had to deal with will never be known. To the extent that leaves the crew open to ridicule, such is life.

In a community that trumpets perfection, it would appear ironic that most are happy with group think and "consensus".
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Old 1st Apr 2012, 16:45
  #1180 (permalink)  
 
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Originally Posted by OC
I rather think we need to be very careful in talking about 'deteriorating skills' because of increased automation. A cursuory examination of past accidents will show many, many examples of where piloting skills were lacking and these on unautomated aircraft where piloting skills were required. Automation has improved aircraft safety immeasurably.......
OC, deteriorating aircraft handling skill level for pilots of automated aircraft are a fact of life. The reasons are myriad but are frequently discussed on a number of threads on this forum. We have always been crashing a lot of un-automated aircraft through the years, mostly for the reason of pilots attempting to fly beyond their abilities/training.

Airlines see pilot training as a business case expense, IMHO there will be no dramatic investment in better/more pilot training.
(There is probably room for simple desktop trainers to maintain basic instrument skills in the budget. That is where they will likely get the best bang for the buck. As a suggestion, airlines could put several of these in pilot lounges and provide incentives for using them.)

That leaves better automatic systems to keep the pilots in their 'executive cocoon' while the computers re-configure the aircraft to keep on trucking. This is controversial of course, but allows safety to be improved with minimal cost. How many accidents can you think of that resulted from pilot mis-application of emergency procedures?
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