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TAM A320 crash at Congonhas, Brazil

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TAM A320 crash at Congonhas, Brazil

Old 17th Aug 2007, 05:27
  #1761 (permalink)  
 
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PBL, your reasoning is perfect to the detail and leaves nothing unaccounted, except the facts:

Please read the FDR readout:

At flare point, TL1 goes to idle, TL 2 stays in CLB
EPR1 goes to idle, EPR2 goes up to 1.3 and stays at 1.2 until impact.
Speed is evenly deccelerated from touchdown speed to 90 kts where it impacts.

So, forget all the far fetched theories about slipperyness, autobrake and TL potentiometers and faulty here and faulty there.
It is clear to the open mind that the TL2 remained at CLB detent, thrust never reduced, they got therefore no spoilers and no reversers, thus they never made it.

The only question that is valid: Why did he do it? I think, it's because he thought that you shouldn't touch that TL if there is something wrong with this engine. There is no other reasonable explanation for it.

The technical data is perfectly consistent and absolutly logical. This is not a technical reason, it is a CRM and a psychological reason. We have to concentrate on the human aspect (and its connection to cockpit technology) of this accident. Nothing else.

Dani
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Old 17th Aug 2007, 06:48
  #1762 (permalink)  
 
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re Dani

I tend to agree. Sometimes the most plausible and simplest reason IS the correct one.
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Old 17th Aug 2007, 07:03
  #1763 (permalink)  
PBL
 
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Originally Posted by Dani
Speed is evenly deccelerated from touchdown speed to 90 kts where it impacts.
Nope. Don't agree. The speed curve after 48:36 has a different slope from the segment before 48:36, which was the start of full manual braking.

I also don't agree that the speed goes to 90 kts on the graph.

PBL

Last edited by PBL; 17th Aug 2007 at 07:16. Reason: I might as well give *all* the reasons
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Old 17th Aug 2007, 08:23
  #1764 (permalink)  
 
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mental blockade

The only question that is valid: Why did he do it? I think, it's because he thought that you shouldn't touch that TL if there is something wrong with this engine. There is no other reasonable explanation for it.

The technical data is perfectly consistent and absolutly logical. This is not a technical reason, it is a CRM and a psychological reason. We have to concentrate on the human aspect (and its connection to cockpit technology) of this accident. Nothing else.
Exactly Dani,
I came to the same conclusion long time ago (re post #1027), but I had to recognize that pilots would rather have a technical discussion than considering human issues

Last edited by clearedtocross; 17th Aug 2007 at 08:26. Reason: Quote addition
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Old 17th Aug 2007, 08:29
  #1765 (permalink)  
 
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Although a 30 minute loop would probably not give us the landing briefing, I am puzzled by the 'missing' 20 minutes on the CVR? Anyone know where it went?
BOAC asks the right question.

From a different perspective it seems we are all being "led" to speculate on specifics details of this accident. These information leaks are too obvious for my taste.

I have some questions regarding the CVR transcript we had access:
-Why are we getting the "engrish version"?
-What was the PA made to the pax.
-Why did the FA asked if Congonhas was their destination? Wx or tech prob or both?
-after we are shown the first 2 minutes, it all went strangely silent (or someone kept it from expert eyes) for the following 23 minutes until suddenly HOT-1 wakes up with the startling words "REMENBER, we only haveone reverse". A bit odd don't you think?
-and then the final 5 minutes where you can even see the ATC words, the chimes, the Retard calls, even the sighs... but during 60% of the last half-hour is all silence. Who are they tring to fool?

Although I enjoy the logic /operation / psychological discussions produced on this thread (and I'm very pleased for being able to contribute) I have this strange feeling that we are being led to conclusions. And I don't like it at all.

GD&L
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Old 17th Aug 2007, 08:40
  #1766 (permalink)  
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Re: the CVR. It could be that there is 'chatter' on there which is best away from the public - who knows? Even with the full tape we will almost certainly not have the landing briefing which would normally take place around 30-45 minutes before landing. At least, unless the tape is damaged, the investigation teams will have the whole tape, and they, 'Dani' and 'clearedtocross' are the only people who can try to decide the cause, and there may well be something in the missing minutes which is important and not releasable at the moment. It would be interesting to have a Portuguese version of the transcript as mentioned before since there is doubt about the double translation of some of the words used.

Tempting as it may be to allocate an 'HF' cause here, ALL avenues must be thoroughly explored. It has always been easy to blame a dead crew,
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Old 17th Aug 2007, 09:59
  #1767 (permalink)  
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Originally Posted by BOAC
Tempting as it may be to allocate an 'HF' cause here,...
There are, obviously, at least two root-causal factors in this accident and, equally obviously, one of them is not crew-HF related.

This is true even before one starts thinking about cockpit ergonomics, procedure design, and so forth.

Some of the last few posts have been speaking as though there might be just one. I hope that was just a matter of injudicious rhetoric, and not reflecting what people really think.

PBL
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Old 17th Aug 2007, 12:17
  #1768 (permalink)  
 
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Nope. Don't agree. The speed curve after 48:36 has a different slope from the segment before 48:36, which was the start of full manual braking.
I also don't agree that the speed goes to 90 kts on the graph.
Then we have a problem here. You really want to tell me that there isn't a constant braking and that it does not stop at 90 kts? Are we talking about the same graph? Are you maybe looking at the graph of the previous flight?

Anyway, braking is absolutly irrelevant. We know that he left the runway with nearly 100 kts. This is because engine 2 was still thrusting with approach power. Can we agree on that?

All data is absolutly consistant with the only mistake this crew ever did: They never retarded TL 2.

That's what the Airbus guys realized immediatly (not after 2000 posts!!) and gave out the clear and unmistaken memo to all Airbus pilots: "At this stage of the investigation, and as already indicated in the previous AIT n3, Airbus remind all operators to strictly comply with the following procedures:
A- During the flare at thrust reduction select ALL thrust levers to IDLE.
..." [end quote]. It could not be more precise.

Please stop all theories about what could have gone wrong inside the thrust quadrant aso, the only discussion we should continue is to why the CM1 left TL 2 in CLB detent and what ergonomic improvement could be done to avert another (a third or even more) case.

Dani
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Old 17th Aug 2007, 12:25
  #1769 (permalink)  
 
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Danl

so, why prior to this crash, hadn't that Airbus statement about retarding BOTH thrust levers been trained into every pilot?

If it were so well understood, why did they have to say it again? was there some room for misunderstanding in the aircraft manual?
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Old 17th Aug 2007, 12:30
  #1770 (permalink)  
 
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Dani...
Please stop all theories about what could have gone wrong inside the thrust quadrant aso,
Agreed... whilst the "theory" route I am sure will be examind by the pros, let's leave it to them. It is surely only a small probability?
the only discussion we should continue is to why the CM1 left TL 2 in CLB detent and what ergonomic improvement could be done to avert another (a third or even more) case.
I am not sure we should discuss this in too much depth without the appropriate qualifications / training. As for "what ergonomic improvement... " I again do not believe much needs to be done. It has been addressed by the MEL change, and the timing of that change, and/or promulgation seem unfortunate to say the least

AFAIK there have been ~3 recorded instances where the failure to retard did, or might have occurred (2 x accident, 1 x experience early in this thread?). All were operating under the (now changed) MEL for 1 T/R Inop. So amongst millions of Airbus landings, we have ~3 exhibiting a common "HF error" all with one other "factor" which seems to lead to the error. Remove that factor (now done) and the driver for the "error" seems to have gone. In fact, one better, the new MEL (select full Rev on both) also improves / changes the logic trees...

I am sure there will be many other recommendations / lessons in the Final Report, but as you say, I think the Airbus advice from shortly after the accident cures the basic root causes...

NoD
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Old 17th Aug 2007, 12:37
  #1771 (permalink)  
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In the "Estado de Minas"

In Brazil there are more than one group investigating the accident and they are not necessarily people who understand aviation. We have two CPIs (House and Senate Committees), the Federal Police and of course the Air Force (CENIPA) the agency that investigates aiming at prevention. Today in the newspaper Estado de Minas it says that the Federal Police investigators believe that the cause of the accident was not human error because they have interviewed more than 20 pilots and the vast majority said that it was impossible that the two pilots would leave the right motor T/L without moving it to idle. They now want to know from TAM if some maintenance on that plane was done on the day of the accident when the plane flew first from Belo Horizonte to Congonhas with one crew and then from Congonhas to Porto Alegre and back with the new crew that died in the disaster.
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Old 17th Aug 2007, 12:38
  #1772 (permalink)  
 
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bomarc
so, why prior to this crash, hadn't that Airbus statement about retarding BOTH thrust levers been trained into every pilot?
If it were so well understood, why did they have to say it again? was there some room for misunderstanding in the aircraft manual?
All pilots are trained to retard all TLs on landing. It's rather a "given"... The Airbus goes one further with the "Retard" call due to it's non-moving TLs...

They had to say it again because it seemed to them obvious that this crew had not (as with the other) from the FDR. It is not the manual at fault, it is the "failure" (understandable IMHO) for the MEL advice not to select Rev to be understood in an HF way as leading to the chance the TL would remain in CLB.

It is incredulous to me, and no doubt many, that any pilot would leave the TL anywhere other than idle. However, it seems they did, as have others with this MEL. We are therefore into Human Behaviour factors, and let's leave the trick cyclists to delve into this. Humans are complex and make mistakes - predictable which we train for - and unpredictable, as probably here.

As above, I think the door has been closed on this one now... shame the previous accident was not better / more quickly analysed / publicised.

NoD
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Old 17th Aug 2007, 12:45
  #1773 (permalink)  
 
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marciovp's post needs to be answered...was mx work done on the plane prior to takeoff on the accident flight.

ambiguity in the MEL's language must also be investigated...going from french to porteugese must offer its own challenges.
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Old 17th Aug 2007, 13:18
  #1774 (permalink)  
 
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HF = Blame ???

BOAC, indeed it is most likely that there was not a single hole called HF in the cheese.

But after reading nearly all the posts, most of them dealing with the logic of the airplane, some blaming the manufacturer, some defending, some highly technical, it just seems justified to point to one main factor: An essential and very basic manipulation, the retarding of one TL was not carried out by the crew.

This statement is not meant to overtake any investigation based on knowledge not available to this community and sorted out by true specialists. And most certainly it has nothing to do with blame.

I wonder why the simple reference to human factors immediately calls for an association with blame? Blame - at least in my opinion - is reserved for people acting careless or outright reckless. Human factors is not about blame, even if one accepts that a small part of Human Factors is about reckless behaviour. This is most certainly not the case in this accident.

But the HF issue is important, because it has feedback into other parts of the loop, like training, man-machine-interfaces, system logic and more. Therefore, HF probably yes, certainly no blame, and most important: learning for a lot of us. That's what I praise this thread for.
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Old 17th Aug 2007, 13:55
  #1775 (permalink)  
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Originally Posted by Dani
You really want to tell me that there isn't a constant braking
That's right, I do want to say that. Perform the regression for the points before 48:36, and then for the points afterwards. (Do I need to say: do it from the ground speed line?)

Originally Posted by Dani
and that it does not stop at 90 kts?
Ground speed stops at 95 kts and airspeed a little earlier and a little higher.

Are we talking about the same graph? Are you maybe looking at the graph of the previous flight?
I guess it is possible that you are not working from the same graphs as I am, but I am more inclined to think the difference is that one of us is not as careful an analyst as the other.

PBL
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Old 17th Aug 2007, 14:16
  #1776 (permalink)  
 
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PBL, you really make me laugh. Of course I'm not talking about exactly the correct value. You can't be a pilot, can you? Pilots are used to handle their tools by rules of thumbs and with approximations. Of course there are small deviations from a gradual deceleration. This is lawyer's stuff. Has nothing to do with aviation.

OK, it's 95 kts they left the runway, not 90, so they have been more dead???

Ridiculous...

Clearedtocross, excellent post. I couldn't say it better. Bravo! I think we can closed this thread.
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Old 17th Aug 2007, 14:53
  #1777 (permalink)  

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BOAC

Re: the CVR. It could be that there is 'chatter' on there which is best away from the public - who knows? Even with the full tape we will almost certainly not have the landing briefing which would normally take place around 30-45 minutes before landing.
It's a 2-hour loop recording.
WE should therefore have the whole flight on the CVR, bar damage, as you wrote.
Why am I, along with some people, interestred in the full CVR print-out - and in Brazilian - ?
It's because some of the big answers of this investigation lie in the way this crew functioned.
I have already hinted at the *unusual* or *particular* characteristic of this pairing, of which we only have fragmented and conflicting indications :[LIST][*]What was the RHS pilot real position with the airline ?
What we know is that he was newly hired, highly experienced on Boeing types, and generally regarded as a good and serious operator. Was it as a direct entry command (*), as a direct entry command on a transformation to TRI (**) or as a queue-of-the-list first officer.[*]why was he on the RHS ?
if (*), he had no place on that RHS
if (**), he was at one of his rightful seats -even if he was still being trained- and it could explain the close guard he had on the side-stick (and I presume on the pedals as well)
if (***), RHS was his legal position, but the same actions on the controls that could be deemed *normal* from a TRI become an indication that there was more on the flight deck authority gradient than we know so far.[*]What was the real pre-descent briefing about ?
What we've seen on the CVR was the Captain's concern about the runway and the sole reverse they had at their disposal. Did he insist on the drill ?...
That question seems to me important because it could give us an other look at the crew's mindset.
Why ?
The ONLY situation I know where one would operate a single throttle is the engine shut-down (Retard the throttle, try a relight....etc..) during which time the other T/L would be either in the MCT detent in automatic or handled by the HP....
Can people make mistakes that are so basic ? In this instance, I can't say but I remember an efficient crew at the end of a Four-hour sim training . They were given at the last landing a van crossing their runway which called for an immediate overshoot. On the previous go-around, they were a bit late getting the gear up. On this one, guess what ? They made a mess of the Go-around because both of them were too intent on the gear operation.Never had the right attitude, thrust was late coming...

bomarc,
the MEL's language must also be investigated...going from french to porteugese must offer its own challenges.
THe flight documents are in English, even those given to the French airlines.
Translations come later, inside the buyers' offices.
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Old 17th Aug 2007, 15:00
  #1778 (permalink)  
 
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Why am I, along with some people, interestred in the full CVR print-out - and in Brazilian - ?
Are you aware of any accident where the whole CVR was transcribed for Joe Public tittering? Most reports I read have made have the relevant section(s) available, even then with "non-pertinent" parts removed. From some site or other:
The CVR recordings are treated differently than the other factual information obtained in an accident investigation. Due to the highly sensitive nature of the verbal communications inside the cockpit, Congress has required that the Safety Board not release any part of a CVR tape recording. Because of this sensitivity, a high degree of security is provided for the CVR tape and its transcript. The content and timing of release of the written transcript are strictly regulated: under federal law, transcripts of pertinent portions of cockpit voice recordings are released at a Safety Board public hearing on the accident or, if no hearing is held, when a majority of the factual reports are made public.
If there were "issues" of crew interaction / roles, examples might be pertinent... however, that I hope would be for the enquiry team to decide, not you and me
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Old 17th Aug 2007, 15:00
  #1779 (permalink)  
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Originally Posted by Lemurian
It's a 2-hour loop recording.
- interesting. The 30 minute'ish transcript had me fooled.

Are you certain of that? First flight 13/2/98.

NOD - I quite agree, but why was the tape up to 18:20:39.3 shown?
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Old 17th Aug 2007, 15:33
  #1780 (permalink)  
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Dani,

As I said before once on this thread, I don't respond to ad hominem comments (except like this).

But I do respond to distribution of incorrect assertions by correcting them. I read you now as agreeing with my observations, but thinking them purposeless.

If you are ever, heaven forbid, in an accident situation, with your fellow pilots on PPRuNe pointing the finger at you and saying "that's the cause, end of story, not that we're blaming anyone, you understand", not to speak of your employer, his insurer, the regulatory authorities and the public prosecutor (whose job is to assign blame), then you might change your mind on the value of careful analysis. If it happens, I'll be glad to help.

PBL
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