Interesting note about AA Airbus crash in NYC

[theamrad]

I understand all your points made about the VMS - but it still leads me to think about what happened in the lead up to the second event. This isn't the first report by far which had recommended improvements in data acquisition rates for certain aircraft/FDR installations - and this is something in common with other investigative authorities' reports around the world. You're probably familiar with what I think is the best example of the problem concerning low data rates or too few parameters recorded: The "difference in opinion" between the NTSB and Boeing in regard to the investigation of the Colarado Springs accident - and even more demonstrative - comparing how the NTSB REASONABLY interpreted/interpolated the data - and how Boeing did!(in an unashamed attempt to mitigate future potential liability). In this case, any of my criticism is not meant to suggest that I think there was any malice involved or that I think there was a hidden agenda on the boards part.

The data collected by the FDR is certainly not in the same “league” as far as the frequency of data samples taken for things like aircraft
certification is concerned

That is true - but we also know of the additional use of a secondary, non-crash protected/secured system of data acquisition used by some airlines (usually billed as being for better/more cost effective maintenance handling). This system has already provided far superior data than the FDR allowed in the investigation of one particular incident I know of - (uncommanded spoiler movement on a B744).
When problems associated with FDR data have been a feature of so many accident investigations, perhaps the longterm route to solve this problem is a total revamp of the FDR philosophy - and use of current digital recording technology in a total revamp of the system. I think that would be preferable to (what it sometimes seems like to me) continually reading phrases like "Require that within 2 years, all 'brand x' planes be retrofitted with a flight data recorder system capable of...... . Then we would have a dual use system (airline flight
performance/cost/maintenance monitoring and FDR usage) in one system, large sampling rates, a myriad of parameters recorded and a system which actually provides some cost benefit to the operator.

As you suspected, I don't have any issue with simulator fidelity (A previous NTSB recommendation to Boeing about wet/slippery runway sim fidelity and the excursion case accepted). The only relevant issue in my mind concerns the rudder pedal sensitivity used in these tests, which I refer to later. There is one point apparent to me in an incidental way - Airbus, and others, apprehension about the use of the sim for upset training when obviously outside the envelope. While of course I agree with the problems voiced and that training under conditions where the sim is not able or intended to emulate a particular aircraft could lead to potential negative training - when I think that both main OEM's have taken what seems to me the same stance, I wonder how the general aviation body feels about the arguement: for sim training - Upset situations outside the range where sim fidelity cannot be guaranteed versus no sim training at all for those cases (full stall for example)?

To get back to the matter at hand - as far as the simulator tests were concerned - I was deliberately trying to stick to one issue concerning them. That was my point about "most" of the testers using some rudder to recover. One of my reasons for that was that this was the very same simulator set up which was used in the initial, criticised training of AA pilots. Specifically, the deliberate lack of control response when upset scenario is initiated which was reported as a time lag. Also, the second point, which I think limits the strength of arguement comes in
the next section: 1.17.1.2.7 Comparison of Rudder Pedal Responses in the A300-600 Airplane and the American Airlines A310/300 Training Simulator, - this shows that the pedal response in the simulator is considerably less sensitive than that in the aircraft. Far from damaging my point of view - I believe that this is one of it's strong points. Since the board believed, in their opinion of the AA advanced manoevering program, that the pilot was somehow conditioned to inappropriate use of rudder - if for a moment I accept that ascertion to be correct - why did they not apply the same logic to possible conditioning of the pilots expectations of rudder/rudder pedal response from the simulator?

As far the Airbus ground tests were concerned - I believe again that validates my point of view. I agree it's a tough test - but, nevertheless, when they tried the "50% condition" they got reduced aileron - but NOT reduced rudder. When you say "what you believe the test results show", it makes me think that the tests show what the tests show. I'm not trying to be flippant in saying that - but it makes me think that you believe I question the the finding of the board:

"Because of its high sensitivity (that is, light pedal forces and small pedal
displacements), the Airbus A300-600 rudder control system is susceptible to potentially hazardous rudder pedal inputs at higher airspeeds."

I don't disagree - I agree 110%.

The rate of FDR data acquisition is irrelevant unless you believe that the airplane could have been doing something really “screwy” between

FDR captured data points and return to the same state every second or every one-half second.

I'm not saying that - but i'm not quite agreeing either - at least in terms of degree. Of course you're comments concerning momentum of a large transport are true, but I'm not trying to suggest this aircraft was in or heading for an upset - but there's doubt in my mind about pilot perceptions. If I had only read the report and nothing else - I would probably sway more in favour of the second event being nothing unusual. However, I think ALL the evidence given in relation to metrology/wake turbulence effects during the public hearings warrants ,IMO, a bit more balanced/careful consideration than, for example, the casual inclusion of the statement "nothing extraordinary" by the main author of the wake vortex report in the board's final report. Doubt is raised in my mind about the POTENTIAL for something beyond the bounds of the "average" wake encounter in consideration of ALL the evidence which was available to me, and not just the final reports limited (very IMO) summary of the wake vortex data.

None of the pilots used full rudder except when they were asked to – and none of the pilots reversed the control inputs.

But, as I've tried to indicate, they were in a sim which demonstrated, to a reasonable approximation, half the pedal sensitivity that the real aircraft does (section 1.17.1.2.7). Therefore, they had a better chance of getting the amount of rudder they wanted and not ending up in an APC event. On that one statement - I think the benefit of doubt should have been placed with the PF.

But why was he using rudder in the first place?

We already know that most of the board's testers used some rudder when confronted with an upset - and by extension - I believe most line pilots would react in the same way. As for the PF here; Again this comes down to whether he thought he was in, or entering an upset or not. Was he? Almost without doubt/obviously - no. Did he think or perceive he was heading for one? Possibly. Why do I think that? Because, if the second encounter was just the same as the first, and it really was "nothing extraordinary", and he didn't perceive anything unusual - why on earth did he go for rudder in the second - and not the first? When pilots experience wake turbulence every day of the year to some degree or other, when so many consider that it's 'nothing unusual', and if the second event was no different from any other wake encounter - how could the PF in this case of lasted for over 1,800 hours on type?

In my estimation, on the basis of logic, reasonable doubt, the diligent and careful manner in which this particular accident was investigated, and the voluminous amounts of raw and refined data, I think the Board’s report on this one is pretty accurate.

For the most part I agree. As I've tried to say previously - it's only one element of the report that I really disagree with. And even on that one point - its not because I think they didn't demonstrate diligence - but with all the data at their disposal, and that which I have come to know - they and I reach different conclusions as to the role of the PF versus Airbus in the equation.

It's no surprise that this accident has generated disparity among some people - and it's likely it won't be the last. For a good example of that WITHIN a report, check out the report of NZ60's 'erroneous' glideslope capture.
For example: That report states (in part);"The crew were cohesive and had planned carefully for the duty."

while an NTSB submission to the same report states: "This incident approach appears to demonstrate a lack of proper preparation, inappropriate approach procedures, and a breakdown of crew coordination and crew resource management."

AirRabbit, I think at this point we're going to have to agree to disagree, otherwise this is going to go on and on and we'll just end up going around in circles.

[AirRabbit]

Hi theamrad

(T)here's doubt in my mind about pilot perceptions. If I had only read the report and nothing else - I would probably sway more in favour of the second event being nothing unusual. However, I think ALL the evidence given in relation to metrology/wake turbulence effects during the public hearings warrants ,IMO, a bit more balanced/careful consideration than, for example, the casual inclusion of the statement "nothing extraordinary" by the main author of the wake vortex report in the board's final report. Doubt is raised in my mind about the POTENTIAL for something beyond the bounds of the "average" wake encounter in consideration of ALL the evidence which was available to me, and not just the final reports limited (very IMO) summary of the wake vortex data.

Of course, as we agree (I think) there is always going to be room for some doubt. The question then becomes whether or not a particular thing is “likely” or “not likely;” or, is the doubt beyond reasonable?

From that, I think the question is relatively straight forward: Did the second wake turbulence encounter contain something that the first one did not? The preceding airplane did not change, except for the possibility of flap retraction (if the JAL crew delayed that long) – which, as I know you recognize, would only decrease the severity of any vortex generated. As far as we know there are no atmospheric condition(s) that could magnify the effect of an existing vortex.

According to the FDR a comparison of the aircraft responses to the first and second encounters compare as follows:
Variation in Longitudinal load factor:
First encounter 0.04 G drop Second encounter 0.07 G drop
Variation in Lateral load factor:
First encounter 0.07 G shift left Second encounter 0.05 G shift left
Variation in Vertical load factor:
First encounter 0.03 G drop Second encounter 0.04 G drop

With the amount of experience humans have in discerning a one-hundreth or a two-hundreth of a “G” difference, I would say that anyone would have concluded that these two encounters were, at the most, very, very similar.

But, as I've tried to indicate, they were in a sim which demonstrated, to a reasonable approximation, half the pedal sensitivity that the real aircraft does (section 1.17.1.2.7). Therefore, they had a better chance of getting the amount of rudder they wanted and not ending up in an APC event. On that one statement - I think the benefit of doubt should have been placed with the PF.

Granted, there may have been a difference in the “sensitivity” of the rudder pedal “feel” between the airplane and the simulator. That is primarily due to the fact that the airplane uses tension regulators and cables where the simulator uses software control of direct hydraulic pressure or electric motors to manage control “feel and application.” However, with the simulator being more sensitive, my experience is that this makes it more difficult, not less so, to get the amount of rudder desired. Additionally, if you carefully note the graph (Figure 18) depicted on page 91 of the report, you can see that the representative curves for the airplane and simulator rudder position/sensitivity are considerably different at the higher airspeed for application of “normal rudder pedal force.” However, when “high rudder pedal force” is used, the trace of the aircraft results very closely compares to that of the simulator.

We already know that most of the board's testers used some rudder when confronted with an upset - and by extension - I believe most line pilots would react in the same way. As for the PF here; Again this comes down to whether he thought he was in, or entering an upset or not. Was he? Almost without doubt/obviously - no. Did he think or perceive he was heading for one? Possibly. Why do I think that? Because, if the second encounter was just the same as the first, and it really was "nothing extraordinary", and he didn't perceive anything unusual - why on earth did he go for rudder in the second - and not the first? When pilots experience wake turbulence every day of the year to some degree or other, when so many consider that it's 'nothing unusual', and if the second event was no different from any other wake encounter - how could the PF in this case of lasted for over 1,800 hours on type?

Two things here: first, you have to recall that the “upset” recovery in the simulator had the simulator controls effectively rendered useless for the first part of the roll – that means that any pilot response to counter the roll would have been ignored by the simulator’s computer. Only after the simulated airplane reached a pre-set roll angle did the computer allow the pilot’s corrections to be applied. In all situations, the roll correction with just the ailerons (as most pilots initially attempted) did not work. Well, it didn’t work because the simulator was programmed to not allow them to work. When the pilot saw the inability of the aileron controls to be effective, he applied the only additional control available – rudder – which each pilot used, sparingly, I might add, and, if I may offer a speculative comment, probably out of anxiety and frustration. In a fully responding simulator or airplane, the pilot would have recognized the effectiveness of the aileron to counter the roll and if the upset was sufficient to cause the roll to continue with increasing aileron application, I think it prudent to, at that time, add a rudder input. But, as our PF recognized in the first encounter, use of rudder was not required.

That brings me to you point about whether of not the PF thought the second encounter was “more” than the first. The FDR seems to refute that idea. However, we know that the PF was a bit concerned about the potentials of following the heavy JAL B747. I direct your attention to the CVR where he queried the Captain regarding the ATC supplied separation at takeoff; “you happy with that distance?” When the Captain indicated that it was “OK,” the PF queried him yet again; “so you’re happy?”

I think the PF was nervous about the JAL B747 – probably more nervous than the Captain or you or I would recognize. I think the first wake encounter (handled nicely by the PF) merely made him more “on edge” in anticipation. With the on-set of the second encounter, I think the PF’s self-control was severely taxed, and he over-responded physically while trying to sound like he had everything under control.

However … you may be correct. Perhaps we are destined to agree to disagree on the finer points of this particular accident. Let me say though, I have enjoyed reading your thorough and thoughtful comments. I hope all of us in the industry have learned from this accident and all the discussions that have taken place as a result. AND, sir, let me say that I would be proud to share a cockpit with you any day. Cheers!

[theamrad]

AND, sir, let me say that I would be proud to share a cockpit with you any day. Cheers!

Thanks a lot AirRabbit, that would be an honour, sir. I think this has been a well teased out debate.

The preceding airplane did not change, except for the possibility of flap retraction (if the JAL crew delayed that long) – which, as I know you recognize, would only decrease the severity of any vortex generated

I glanced over some of the evidence at the public hearing tonight - unfortunately not enough time to delve too deeply - but did find some of the relevant parts. As far as flap retraction making a difference is concerned, until being reminded, I would have agreed with you on that point - but it seems we would both be a bit wrong, at least according to Dr. Proctor(chief author of the wake vortex report for the NTSB), who stated that he thought flap retraction would have very little effect on the strength of the wake vortex. In his opinion, the main factors were weight, speed and wing span. He also stated that even the initiation of climb, with the accompanying change in wing loading, would have very little effect on the strength of vortex generated. Personally, I fell compelled to apply a little scepticism to some of his opinions, in light of the fact that when asked what effect the presence of winglets would have on the strength of wake vortex - he stated that he could not answer?!? It has always seemed strange to me that the chief author of the wake vortex report refused to answer some of the questions concerning the relevant matter and cited the reason for doing so by saying he was not an aerodynamicist.

Another matter which was evident in the wake vortex report was a discrepancy between the 'ambient' winds which both aircraft flew through and were recorded by their respective FDR's. Considering their closeness in time and space, Dr. Proctor only acknowledged the difference, but could offer no possible explanation for it. Maybe the presence of at least some turbulence? Maybe - maybe not

With the amount of experience humans have in discerning a one-hundreth or a two-hundreth of a “G” difference, I would say that anyone would have concluded that these two encounters were, at the most, very, very similar.

That brings me to you point about whether of not the PF thought the second encounter was “more” than the first. The FDR seems to refute that idea.

Dr. Proctor stated during questioning that he believed that it was possible the accident airplane could pass through the core of a wake vortex and leave no indication of the passage on the FDR. That puts us in a paradoxical situation! Considering he was the official "wake vortex man" - If I accept that statement in isolation - it strengthens my argument and weakens yours - If I reject it, it weakens my argument and strengthens yours?!? But he also stated that he thought the wake vortex counter would have been "nothing extraordinary". That leads the two of us back to our discussion about the efficacy of the FDR's acquisition rate. But I'm just getting to one of the points which threw doubt up for me early on. The paper titled ""An Engineering Study of the Unsteady Response of a Jet Transport During a Wake Encounter and the Transitional State of Potential Crow Instability", and the work/remarks of Dr. Anthony Brown, NCA Canada. Dr. Brown has an interesting, indeed probably valid, explanation for events that day and how the FDR, pilot perception and APC could have played out - that is if we accept that these conditions existed on that day - Howevr, Dr. Proctor dismissed the idea completely.

My point isn't that I accept or believe the suggestions of Dr. Brown - but rather it's something which makes me approach the conflict of ideas with an open mind - as opposed to just accepting Dr. Proctors evidence, who, IMO, demonstrated quite definitive opinions sometimes - but refused to give answers at other times - which I think should have been within his area of expertise, if authoring a report on wake vortices. At the end of the day, I find it difficult to even form an opinion on who is right - I'm not an expert in that field, Dr. Proctor was called to report/give evidence and Dr. Brown wasn't.

I think the PF was nervous about the JAL B747 – probably more nervous than the Captain or you or I would recognize. I think the first wake encounter (handled nicely by the PF) merely made him more “on edge” in anticipation. With the on-set of the second encounter, I think the PF’s self-control was severely taxed, and he over-responded physically while trying to sound like he had everything under control.

It seems like your suggesting that PF was primed to expect a wake encounter. I think that was discussed at one point during the public hearings and I tend to agree with you. It's probably something which I've tended to overlook a bit. The first time I ever read the CVR transcript - I thought it a bit strange that he should ask that, considering his experience level.

I hope all of us in the industry have learned from this accident and all the discussions that have taken place as a result.

Hopefully! Concerning what "design manoeuvring speed" means, I think it has woken up a lot of people, and maybe refocused attention on the importance of a few related things such as turbulent air penetration speeds, etc.

While I feel quite strongly about my reservations in this case - in general I think the NTSB do an outstanding job, and not only within the US - many states around the world call on their expertise or technical assistance. In certain circumstances it sometimes looks like they have to step into a bear pit of parties and their conflicting interests. To me, it always seems like they lost their naivety over the 737 rudder reversals issue. The only room for improvement that I can see is with the relationship between the NTSB and FAA over the timely enforcement of NTSB recommendations. Since many places around the world take their lead in regulatory matters from the FAA, it's a matter that concerns safety both outside as well as within the US.

Maybe we'll meet up here for another debate on some other thread at some stage, and I'll look forward to that.
Regards.

[AirRabbit]

Originally Posted by theamrad

...in general I think the NTSB do an outstanding job, and not only within the US - many states around the world call on their expertise or technical assistance. In certain circumstances it sometimes looks like they have to step into a bear pit of parties and their conflicting interests. To me, it always seems like they lost their naivety over the 737 rudder reversals issue. The only room for improvement that I can see is with the relationship between the NTSB and FAA over the timely enforcement of NTSB recommendations. Since many places around the world take their lead in regulatory matters from the FAA, it's a matter that concerns safety both outside as well as within the US.

Hi theamrad:

Again - thanks for the very thoughtful comments. I very much agree with you on your comments regarding the NTSB. Not only do they provide the world's aviation interests some very valuable safety information as a result of the investigations they conduct, I think they also serve a necessary function as an "official" critique of FAA rules, practices, and policies.
In fact many - perhaps most - of the safety recommendations the Board makes to the FAA are incorporated into the business of US aviation.

However, because of the burdensome regulatory process and because the opportunity for those being regulated to register complaints with their elected officials in the US Congress is always there and used whenever thought necessary, it isn't as "easy" as it may seem to just implement the Board's recommendations. And, to be completely fair, there are some recommendations that border on the superfluous.

I also agree with your comment that you believe "they lost their naivety over the 737 rudder reversals issue." With me, it was the Air Florida crash in Washington, DC where the "causes" and "contributing causes" determined by the Board seemed to either overlook or disregard evidence contained in the report. Again, while, like you, I do not intend to impugn the integrity of the Board or of the extremely fine professionals who have provided, and continue to provide, valuable information to aviation interests, and while there is little doubt that some extremely valuable information was generated from that particular accident investigation (information that I believe has benefited all who fly in winter weather), I also believe the "naivety" you mention was uncovered (in at least this instance) for anyone interested to see.

I, too, look forward to exhanging ideas, thoughts, and beliefs in future topics here. It is "hangar flying" like this where I believe many really are able to "get into" the "nuts and bolts" of what aviation really is. Thanks again for your generous contributions to that effort!

[Clandestino]

It seems that no one here claims that A306 rudder is impeccable, after all NTSB listed its sensitivity as a contributory factor.

Where we split in two groups is when we discuss what should be done about it.

First group says: almost nothing; while unusal, it will not bite you if you use it properly. Just emphasise the proper use and teach the pilot what to expect if they misuse it. Extremists like me even claim that it was covered in basic aerodynamics during our ATPL courses and go on to lament about declining quality of pilot trainning, learning by rote in order to tick the boxes, "what you don´t know can kill you", etc, etc...

Second group thinks that it is serious design fault, it should be reworked, the airplane shouldn´t be allowed to fly, etc.. Implicit in this position is that airline pilot really need totally foolproof systems to do their jobs properly.

Personallly, I find second attitude very patronizing, almost to the point of being insulting. Then again it´s not a fact; just my opinion.

[RatherBeFlying]

Given the unusual behavior of the rudder at 250 kt. crew training needs to address that behavior. Today this happens.

As to the PF's expressed concern of closely following the JAL 747, I note that Airbus somehow did not see fit to hire a 747 and further research the wake dynamics in an A306 and see what would happen if they tried just one pedal movement in the wake.

[DozyWannabe]

Originally Posted by RatherBeFlying

As to the PF's expressed concern of closely following the JAL 747, I note that Airbus somehow did not see fit to hire a 747 and further research the wake dynamics in an A306 and see what would happen if they tried just one pedal movement in the wake.

I know I'm no professional pilot, but I thought I answered this one before:

Originally Posted by DozyWannabe

Probably because they were not invited to. In any case, the only precursor for such an event would be the 737 rudder / 727 wake encounter tests that were performed in the lee of the USAir 427 accident. In that case, the 727 was provided by the FAA and the 737 from USAir upon request from the NTSB. The manufacturer (Boeing) was not involved directly in that experiment.

[airsupport]

Second group thinks that it is serious design fault, it should be reworked, the airplane shouldn´t be allowed to fly, etc.. Implicit in this position is that airline pilot really need totally foolproof systems to do their jobs properly.

Personallly, I find second attitude very patronizing, almost to the point of being insulting. Then again it´s not a fact; just my opinion.

I certainly belong to what you call the second group, and the main faults I worry about HAVE been corrected now, it is just whether or not this exact type should still be flying or not.

I find YOUR comment very patronizing to the point of insulting, as it is NOT implicit in this position that the pilots need totally foolproof systems to do their job properly, just that the passengers (and crews) should expect to only fly on safe aircraft.

[DozyWannabe]

At the risk of looking like a hawk (not to mention a tiresome bore) on this thread, I think that it's fairly obvious that there is nothing wrong with the type concerned as long as pilots fly it as their training prescribes.

Yes, if aircraft are prone to pieces falling off then we should take notice - I don't think anyone would disagree with you there. I'm sure that there are studies galore on composites and water retention that could be used by people to prove things one way or another, but the fact remains that in this incident, the craft was flown outside its safe parameters before any problems were recorded, and it can be proven with very little doubt that flying outside those parameters in the way that this craft was flown would have caused the damage that led to its loss.

[barit1]

Agreed, DozyWannabe, although I'll take issue with your use of (ahem) "parameters" when you mean limits.

(In a weaker moment, I might speculate that you had a metaphorical useage of "perimeter" in mind, in the sense of a boundary or constraint...)

[airsupport]

At the risk of looking like a tiresome bore

Finally we agree on something.

[Yankee Whisky]

Vertical stabilizer loss

I am a bit late on this discussion but my input is based on practical experience flying in (severe) turbulence created by rotor acticity in mountains, mainly towing gliders.
The only way to not overload any airframe and flight control components is "to ride it out" until clear of the region of turbulence.
To fly in the wake of another (heavy JAL), as is the case with the AAL Airbus, is to be avoided but if turbulence is entered "ride it out". Passenger discomfort will result as the result of unusual 'g' loads and attitude changes but more than likely, no total losses. I am assuming the aircraft is handflown and not on autopilot. (note the BAC111 loss over Georgia USA, quite some years ago)

[airsupport]

The point is this was a catch 22.

Someone MAY have exerted excessive pressure on the tail in a desperate attempt to fly the Aircraft, which ultimately caused the tail to fail, HOWEVER it was just a matter of time before something happened as the tail assembly was weakened by this continual trapped water.

[411A]

The fact remains of course that the concerned airline operator had a program of aggressive maneuvering in place (or just before)...and it has long been positively known (since the early days of the B707) that aggressive use of the powered rudder can lead to big problems, as AA found out, first hand.

In short, AA should have known better.

[PBL]

Originally Posted by airsupport

Someone MAY have exerted excessive pressure on the tail in a desperate attempt to fly the Aircraft, which ultimately caused the tail to fail, HOWEVER it was just a matter of time before something happened as the tail assembly was weakened by this continual trapped water

When a tail assembly fails at 1.93 times Limit Load, then it is 29% over certification strength (which is 1.5 times Limit Load). It is inappropriate to call it "weakened". One could more accurately call it "overbuilt".

Originally Posted by 411A

The fact remains of course that the concerned airline operator had a program of aggressive maneuvering in place (or just before)

The operator was warned in 1997 by a joint letter from the FAA, Boeing and Airbus:

Originally Posted by FAA/Boeing/Airbus letter to AA

The excessive emphasis [in AAMP] on the superior effectiveness of the rudder for roll control ... is a concern. Rudder reversals such as those that might be involved in dynamic maneuvers created by using too much rudder in a recovery attempt can lead to structural loads that exceed the design strenght of the fin and other airframe components. The hazard of inappropriate rudder use during windshear encounters, wake turbulence .... should also be included in the discussion.

In other words, the regulator and major airframe manufacturers warned explicitly of the events that happened to AA587 some four years before.

This is considered in Section 3.5 of my paper "The Crash of AA587: A Guide" from November 2004, available from http://www.rvs.uni-bielefeld.de/publ...ashOfAA587.pdf

Importantly, trying to control roll with rudder has dynamic characteristics which lead to oscillatory behavior in all large transports. This is inherent. For this reason and others, the BEA does not consider rudder to be a primary flight control.

There are lots of other things to be said about this accident; I said most of what I think are worthwhile to say in the paper cited above.

PBL

[airsupport]

When a tail assembly fails at 1.93 times Limit Load, then it is 29% over certification strength (which is 1.5 times Limit Load). It is inappropriate to call it "weakened".

That is your opinion, I don't see why you have to rubbish other people's first hand knowledge and experience.

I am NOT a Pilot, and thus am certainly not just defending a fellow Pilot, and I don't really understand what the Pilot did wrong, however if Professional Pilots say he did wrong I accept that.

However, I was there in New York at the time, working on identical Aircraft, and saw first hand the problem with these Aircraft operating in this unique environment, problems that have been corrected since this tragedy.

The Pilot may or may not have done something wrong, I don't know, but I am SURE that there was a problem with the tail of these Aircraft when operating out of NY and down through the Caribbean at that time.

The final straw, or final link in the chain, MAY have been the action of the Pilot, but there is rarely a single cause in any Aircraft Accident.

[lomapaseo]

That is your opinion, I don't see why you have to rubbish other people's first hand knowledge and experience

That wasn't personal, it was just the proven facts vs your experience being associated with a postulated causal factor that was not in evidence in the New York accident.

[PBL]

Originally Posted by airsupport

That is your opinion, I don't see why you have to rubbish other people's first hand knowledge and experience.

Dear me. I was correcting you under the assumption that you hadn't read the docket and had just made a mistake.

I'm not sure any discussion with someone who wants to call something that failed at 1.93 times Limit Load "seriously weakened" is going to be very fruitful. I'm curious - do you call the A380 and B777 wings "seriously weakened" also?

Originally Posted by airsupport

However, I was there in New York at the time, working on identical Aircraft, and saw first hand the problem with these Aircraft operating in this unique environment

Maybe, but whatever the problems were, they obviously didn't have much to do with why the tail broke off AA587.

PBL

[PBL]

Originally Posted by IGh

Did you recognize the irony of the SAFETY SYSTEM creating a solution that induced a new failure?

I had missed it until you just pointed it out. Thanks.

I obviously tend toward the view that AAMP may have (you say "likely provided the seed" - I imagine we both want to hedge) reinforced the PF's inclinations towards rudder use, which is what the NTSB found and against which AI, Boeing and the FAA had warned.

It would not be the first time. Accidents caused by in-flight activation of thrust reverse or ground spoilers led to the WoW criterion for deployment, which in turn led Lufthansa to float along the Warsaw runway without any deceleration aids for 9 seconds in 1993, and overrun.

There are other factors, of course, in both accidents.

PBL

[hetfield]

which is what the NTSB found and against which AI, Boeing and the FAA had warned.

Yes, but AFTER this tragic accident!