Interesting note about AA Airbus crash in NYC

[punkalouver]

The National Transportation Safety Board determines that the probable cause of
this accident was the in-flight separation of the vertical stabilizer as a result of the loads beyond ultimate design that were created by the first officer’s unnecessary and excessive rudder pedal inputs. Contributing to these rudder pedal inputs were characteristics of the Airbus A300-600 rudder system design and elements of the American Airlines Advanced Aircraft Maneuvering Program."

I'm not sure if this has been covered before but a safety award was given for developing that program five days before the accident.

http://www.flightsafety.org/citations/vanderburgh_cit.html

[Airbubba]

Yep, this program filtered down to the other airlines. I was given a version of the training that included the hard rudder kicks to get the nose back down to the horizon in some attitudes. I questioned whether you really wanted to do this in a transport aircraft but was told that it was all within the design envelope. I guess it turns out that it wasn't...

[jondc9]

to all:

this is one of the few times I must disagree with the NTSB. I don't blame the copilot for this crash.

I've flown planes that have wonderful little gadgets called "rudder limiters", reducing the amount of rudder travel the faster the plane goes.

I've also flown a wonderful plane that had a placcard that clearly said: above 30,000feet limit control wheel throw to half travel.


Prior to this crash, I would have believed that the only rudder limit would be the VNE/Vmo speeds and the only other limit would be me getting sick from moving the rudder too much.

IF the airbus rudder will fall off and kill everyone aboard if the pilot kicks the pedals too much, then there better be a PLACCARD in the face of the pilots saying so.

Wolfgang was right, why do we need rudders? ( this is rhetorical and meant to make you think and not to be answered)

[fmgc]

Do you need it placarded to say "Pull stick back to raise the nose"?

[grumpyoldgeek]

Apologies if this has already be thrashed to death...

But as a student pilot who has read Wolfgang's book three times, I'd really enjoy reading the thoughts of you high-timers as to rudder use and the ability to destroy a plane with large rudder movements.

[jondc9]

Dear FMGC:

you said: Do you need it placarded to say "Pull stick back to raise the nose"?


if you believe this, you are a mediocre pilot...pulling back on the stick doesn't raise the nose, it increases angle of attack, and when you go past the critical angle of attack the NOSE COMES DOWN and all the pulling you do won't bring it up (for conventional aircraft)

why not read Wofgang's book again. or read it for the first time...it might help!

[jondc9]

dear grumpyoldgeek:

I see you are from northern california. I used to teach out of PAO...maybe you fly there?

AS to the rudder question. I think reading "Stick and Rudder" is excellent and it will keep you quite well and safe. 3 readings isn't enough, read it till you can quote it.

You will recall that Wolfgang talks about why there is a rudder...things like adverse aileron yaw, crosswinds and the like. Of course a multi engine airplane with engines on opposite sides of the fuselage one needs a rudder to help control the plane in an engine out scenario.


As I mentioned , use of rudder within the limitations of the aircraft should be just fine. as you probably know, the rudder is used by the yaw damper system to keep things like dutch roll under control on swept wing planes.


I think using the rudder is fine provided one knows the plane, AND PROVIDED THE BUILDER OF THE PLANE WARNS THE PILOTS PRIOR TO FLIGHT OF ANY PROBLEMS LIKE THE AIRBUS 300/310.


One time, in a small plane I was flying ( piper turbo arrow 3) the ailerons failed in flight and landing was accomplished using rudder and stabilator (piper uses stabilator instead of elevator).

If a plane has a rudder,know what to do with it and use it. If you can design one without a rudder, all the better. As you know, Wolfgang speaks well of the ercoupe aircraft.

[barit1]

Without having the reference before me, I believe that the rudder limiting approaches between Boeing and Airbus are quite different. IIRC Boeing reduces rudder gain (i.e. a given force on the pedals gives less rudder displacement as airspeed increases); whereas Airbus maintains a fixed gain but limits the pedal travel, thus less pedal force is needed to drive the rudder to the stops.

To me, even though I may not have quoted the details exactly, this is a very substantial difference in control philosophy, and ignorance of this fact by this crew (and I suspect many other crews) is a VERY costly ignorance.

I visited AA's training center back when DFW was in early stages of construction, and they were just beginning the high fidelity simulation program. I don't think this degree of "glossing-over" would have been tolerated back then.

[DozyWannabe]

Without having the reference before me, I believe that the rudder limiting approaches between Boeing and Airbus are quite different. IIRC Boeing reduces rudder gain (i.e. a given force on the pedals gives less rudder displacement as airspeed increases); whereas Airbus maintains a fixed gain but limits the pedal travel, thus less pedal force is needed to drive the rudder to the stops.
Pretty much exactly correct, according to my old teacher's RISK bulletins.

Also worth noting is that the A300 series has a very powerful rudder, with the moving parts taking up a significant percentage of the vertical stab's total area. The video from AA's training sessions implies that the primary focus was on the DC9/MD80 series, which was understandable given that it made up a significant portion of AA's fleet at the time. I don't have the relative sizes to hand, but I'd imagine that the active rudder section of the DC9's vertical stab would be significantly less.

While we will never be 100% sure, the PF was expecting significant wake turbulence and may have perceived the shortening of the rudder pedal's travel to have been a consequence of the JAL 747's wake rather than the rudder limiting kicking in. Either way no matter what aircraft was being flown, repeated rudder reversion in a sideslip would likely lead to the same structural failure that was seen in this incident.

IMO there were lessons to be learned by pilots, manufacturers and airlines as a result of the issues the AA587 accident brought to light and it's a shame that some of those lessons have been submerged due to territorial disputes (AA as a corporate entity, AA's pilots and Airbus were all a little to blame there).

[Clandestino]

AND PROVIDED THE BUILDER OF THE PLANE WARNS THE PILOTS PRIOR TO FLIGHT OF ANY PROBLEMS LIKE THE AIRBUS 300/310.

Interesting point! Even more interesting after you read page 156 of NTSB report (http://www.ntsb.gov/publictn/2004/AAR0404.pdf), which says:

To elevate the characteristics of A300-600 rudder system in hiearchy of contributing factors ignores the fact that this system had not been an issue in some 16 million hours of testing and operator experience - until the AAMP trained pilot flew it.

It wasn't rudder deflection alone that tore off the fin, it required help from large sideslip, created by previous rudder cycle. Granted, if pedal forces were heavier, F/O wouldn't be able to make rapid rudder reversals that led to accident. Hard rudder kicks below Va are not bound to hurt your airplane, as long as they're not alternating.

Personally, I think the greatest fault lies with folks who devised such unrealistic scenario for AAMP as overbank with roll control disabled. Chances are that F/O reacted as he was trained on the sim, found out that there really was no need for so much rudder, corrected excessively, kicked again in direction of first input... we know the rest.

BTW ercoupe does have rudders, it's just that their actuation is somewhat unorthodox.

[DozyWannabe]

Found it:

http://www.cs.york.ac.uk/hise/safety-critical-archive/2004/0735.html

Jon, you may find this part interesting:

When it came out that the certification standards did not
require anything under dynamic rudder movement (Michael Dornheim
of AvWeek was the first to report this extensively) I was
surprised. Then Clive Leyman, former chief aerodynamicist on
Concorde, pointed out to me that it is very hard to measure
and analyse forces on the rudder under such movements. It is
obviously possible nowadays, with the highly improved codes
that have been made available over the last thirty years since
the airplane was certificated, else Airbus would not have been
able accurately to calculate the overload in this accident.

Airbus could not give the precise load to failure figures on the A300 because the methods of measuring such things were not sufficiently advanced when the A300 series was designed.

And here:

Furthermore, it is documented that
they had been warned, not only by the manufacturer but by the
certification authority in writing, years previously about
such use of the rudder.

(emphasis mine)

[Trentino]

After all these years and all this arguing going around I still find it terribly unnerving that a transport category aircraft lost a control surface after flying over my house.

being only an airplane driver and somewhat unfamiliar with the certification process I find it terribly hard to swallow that I can shake apart my aircraft at such a low speed.

Also, maybe this is a moot point but that Japan air 74 that leaves at MTOW has a very low climb gradient, maybe the lowest other than the odd 340.
I usually see the A300 outclimb the 747 so it seems that wake contact would be minimal.

Conspiracy theories aside, could there be more to this than just the wake theory?

[bubbers44]

I have all of those credentials also but it just gives you a pilots license to learn how to fly an airplane. The FO of the A300 had nothing to do with the crash that day. The NTSB could not blame airbus for that crash so blamed the dead FO. Look at the pictures of the vertical stab that separated from the airplane and see how when we got the airplane it was stapled and how the failure was parallel to the staples they put in to repair it. I also took the AARP course at AA emphasizing the use of rudder at high angle of attack low speed recovery but at 250 knots everybody knows roll recovery is primarily aileron input.

[GlueBall]

In all my years of operating big jets, except for engine failure, I have never encountered an inflight upset that necessiated the use of rudder.

And a procedure of ever having to "kick" the rudders in a large transport category airplane is impractical reality, if not outright stupefying.

The copilot in the A306 who had kicked the rudders in rapid succession had a history of doing so when he was flying B722s at an earlier time; ...this, according to one AA captain who had flown with him, in a deposition that is attached to the NTSB Report.

[Ignition Override]

There have been alleged reports of rudder anomolies on A-300/310s operated by Air France, Interflug (formerly East German), and recently, Air Transat.

Maybe none of these incidents happened.

But if they did, not only Airbus, the US FAA and the NTSB had an excellent scapegoat for the accident, if there is a chance that the same AA 587 aircraft experienced uncommanded rudder deflections. Is it true that after a certain degree of rudder pedal travel, the effect on the actual rudder movement is disproportionate?

Blaming the dead pilot, as always, creates a perfect scapegoat and saves various agencies from public embarassment and huge costs involving testing and training throughout the US fleet(s).

[Clandestino]

Well, gentlemen, DozyWanabe posted excellent link (http://www.cs.york.ac.uk/hise/safety-critical-archive/2004/0735.html) dealing with both AA587 crash and post-mortem investigation. For those of you who didn't bother to follow it, here are some interesting excerpts:

The point seems to have been that because one could not
well calculate such overloads, the industry (regulators and
airplane builders) relied on instilling as Best Piloting Practice
that you Just Don't Do That, because you could rip the tail
off an airplane.

Now, that seems to me both reasonable and consistent with
professional operator practice anywhere. If you Don't Know
(and you know that it can be catastrophic) then you Don't Do.

(...)

It is recognised in the industry, although not apparently
at American until recently, that swinging the tail around with
rudder is something you Just Don't Do. Most pilots of large aircraft
(I would have said: pilots of large aircraft, until I learnt
about American's training) are taught to use rudder only at slow
speed (take off, for example) or to correct yaw in an asymmetric
thrust situation.

(...)

during thirty years of A300 flying, American has been the only airline to rip off (or, in another incident, almost rip off) the tail, and that through
explicit use of rudder

(...)

Nobody I knew, including some avid Airbus Design-Flaw Seekers,
ever doubted that the dynamics of the aircraft as shown on the
FDR were highly inappropriate. The debate centered on whether
one could conclude that the pilot did it (rudder pedal travel
was not recorded on the FDR) or whether some automatic system
had gone awry. Obviously, the NTSB's attempts to find some
rudder control system that had a failure mode that caused such
motion came up with nothing. (I am inclined to think that if
the NTSB cannot find one, then nobody can. They have a lot of
experience and succeeded in finding the failure in the
Parker-Hannefin yaw damper in the B737 after the US B737
crash in 1994, and the failure mode of the thrust-reverser
interlock on the B767 engines after the Lauda Air crash in
Thailand.) So even the design-bashers agree that if indeed
the pilot did it, he shouldn't have done so. The NTSB is finding
that indeed the pilot did it. All else follows from that.



So which part of it you don't understand?

When I was I young lad, one of my instructors told my group that you never, ever rapidly cycle any flight conrol (while airborne, that is), for any reason, on any aeroplane. You could easily get in resonance with airframe, develop severe oscillation and enjoy the view of airframe disintegrating around you. And only after listening to this and a lot more of solid advices we were allowed to sit in our mighty cessna-152s for the first time. Lucky me that the chap who told us that was ex-glider pilot, ex-cropduster, ex-dakota pilot (both Douglas and Lisunov) and ex-DC-10 instructor and not someone who passed aerodynamics and airframe construction test by learning all multiple choices questions by rote and than spent a year or two instructing just to build up hours.

Lucky me indeed, because nowadays, when I open my FCOM, foreword tells me:
the text is not intended to teach the crew how to fly an airplane, but to enable an experienced crew to operate the related airplane type safely and proficiently.

Learn, live long and prosper!

[punkalouver]

Blaming the dead pilot, as always, creates a perfect scapegoat and saves various agencies from public embarassment and huge costs involving testing and training throughout the US fleet(s).
Whether the pilot is alive or dead has nothing to do with the cause or the NTSB's interest in finding the cause. It just makes it more difficult. Notice how much effort was placed on blaming ATR in thr Roselawn accident or Boeing about rudder hardovers despite huge manufacturer resistance. Very expensive results have come from those accidents.

[jondc9]

have we forgotten the A310 that lost a portion of the rudder climbing out of Cuba?

This was after the American crash and pilots had all heard the claims from the American Captain who said the copilot used the rudder too much in the 727.

One thing to consider too is this. How many planes made out of METAL and not composites have had this type of inflight breakup due to use of rudder? (and not the 737, that was a different animal)



And if this dead copilot had been bad on the rudder of the 727, why didn't the system (FAA, Airline, APA etc) wake up and do some retraining?


While we can talk of rapid cycling of controls and potential damage from this, we do have to remember that the copilot was an airline pilot. Very few airline pilots over control for one reason alone...passenger comfort.

[bubbers44]

Jondc9, The fact that none of the other hundreds of captains he flew with had a problem with his rudder usage and none of the flight attendants complained about yaw problems when he was flying I don't think he had a problem needing additional training. No captain would let an FO fly like that. Since both engines snapped off during flight. I always thought the vertical stab separated initially from the front causing the severe yawing and gyroscopic forces necessary to cause the engines to separate from the aircraft. I have no proof of this just as the NTSB can't prove he caused the problem.

[Graybeard]

"Nobody I knew, including some avid Airbus Design-Flaw Seekers, ever doubted that the dynamics of the aircraft as shown on the FDR were highly inappropriate. The debate centered on whether one could conclude that the pilot did it (rudder pedal travel was not recorded on the FDR) or whether some automatic system had gone awry. Obviously, the NTSB's attempts to find some rudder control system that had a failure mode that caused such motion came up with nothing. (I am inclined to think that if the NTSB cannot find one, then nobody can. They have a lot of experience and succeeded in finding the failure in the Parker-Hannefin yaw damper in the B737 after the US B737 crash in 1994...
The NTSB is finding that indeed the pilot did it. All else follows from that."

It's folly to assume the NTSB is immune from political pressure. The USAIR B737-300 crash in 1994 followed a UAL 737-200 crash in Colorado Springs in about 1989, which made no sense until the rudder control reversal was admitted to in 1994. That was in spite of a UAL 737-300 going into rudder control reversal on taxi out in about June of 1991. After that was the PBS special on "The Mysterious Crash of Flight 301", a COPA 737-200 that crashed in the Panama jungle one night in about 1992. Some insiders blamed the Sperry vertical gyro, but to me it had all the earmarks of the Colo Springs crash: rudder control reversal. Five years and three accidents does not inspire confidence the NTSB got it right on AA 587.

GB

[jondc9]

Bubbers 44
I agree with you. I really do.
my faith in the NTSB has been shattered. my belief in backroom political dealings is reinforced.
737 and this airbus, while not identical crashes , just reminds me that the truth is often a compromise and not the truth.
I recall, way back when, in my first 20 hours of flying or so, that the instructor had me demonstrate remaining in a stalled condition and keeping the wings level using JUST rudder. while modern planes allow aileron useage into the stall, this was a nice maneuver. The rudder didn't come off of my PA 28, we didn't break apart in flight.
The DC9 I flew for many years had a rudder limiter, no one knocked the tail off the dc9.
I know of pilots who have transferred off the airbus 300 for the concerns we have outlined. I have told my friends to avoid this aircraft if possible. Until the repairs were made, I would have told them to avoid the L188 too.

[Loose rivets]

How sure are they, that the FP's input was not increasing because of an already developing structural failure?

The feedback may have been so modified, that he was reaching further and further for a familiar response.

[jondc9]

great question loose rivets!

one thing that would help us all in the future is a video/camera system that monitors all critical surfaces AND records this info/video in a black box system.

if the plane had started to come apart PRIOR to massive control inputs by the copilot, whose fault was that?

...

by the way, does anyone remember when AIRBUS was going to be called : JET, for Joint European Transport?

[Litebulbs]

I would imagine that the DFDR would no longer be reading rudder surface position if the rudder/fin is no longer attached to the fuselage.

[punkalouver]

Ahhh...the old conspiracy theorists. No matter what reasonable arguement you put forward or studies are done, they just ask more and more hypothetical questions and come up with more and more theories. Reminds me of TWA 800 and also the Egyptian aircraft accident investigation board.
Hmmm. Now that I think about it, they all had to do with JFK departures.

[jondc9]

litebulb

I think that the DFDR doesn't measure location/position of the rudder as much as it measures movement of rudder actuators...if the actuators moved, we might assume the rudder moved with it...unless the rudder fell off

[bubbers44]

If my theory is correct about the vertical stab failing initially from the front then the rudder inputs by Sten were probably to correct the stab causing the yaw. He was only trying to maintain heading so multiple reverse inputs would be what any pilot would do if the stab was causing severe yaw problems. If you were the captain would you let him thrash the plane around for a common wake turbulence event? I don't think so. Any flight attendant in the back would be severely injured if she was out of her seat for some reason. We all deal with wake turbulence and it is not an emergency, we just have to make that PA explaining how it is like being behind another boat to calm nervous passengers. A lot of politics was in that NTSB final findings.

[interpreter]

There have been many professional views expressed here about the incident but surely common sense says that one does not use violent and full activation of the rudder in any aircraft - especially in one where the feedback to the pilot is not quantitive.

All my training - general and service avaition only and some time ago - taught smooth and increasing pressure, never rapid and opposite.

[DozyWannabe]

have we forgotten the A310 that lost a portion of the rudder climbing out of Cuba?
Hadn't heard about that one, it's important, but not likely to be related - I found this article, and it cautions that Airbus and Boeing were watching it closely.
http://findarticles.com/p/articles/mi_m0UBT/is_2005_March_21/ai_n13458444
It's folly to assume the NTSB is immune from political pressure
...
Five years and three accidents does not inspire confidence the NTSB got it right on AA 587.
I don't think anyone is assuming that, GB. Though their independence from the FAA/airline/manufacturer circle has been considered fairly sacrosanct since the aftermath of the DC10 decompression failure debacle, and that was nearly 30 years ago.
I recall, way back when, in my first 20 hours of flying or so, that the instructor had me demonstrate remaining in a stalled condition and keeping the wings level using JUST rudder. while modern planes allow aileron useage into the stall, this was a nice maneuver. The rudder didn't come off of my PA 28, we didn't break apart in flight.
The DC9 I flew for many years had a rudder limiter, no one knocked the tail off the dc9.
Jon, if you know your physics, you'll know full well that the aerodynamic stresses on a PA28 dont even compare with those on a large transport-category aircraft. I also doubt you were in a sideslip following a wake turbulence encounter when you performed that maneuvre. And I've already said that the DC9's rudder surface area in comparison with the A300's makes that comparision unfair too.
No-one 'blamed' the pilot - he was doing as he'd been trained. That training should not have been applied to all aircraft in the fleet. It was a systemic failure.

Also, I think that there's some confusion creeping in - no one was saying that putting full rudder in was the wrong thing to do. They were saying that putting in full rudder in opposite directions while in a sideslip was a bad idea.

[Litebulbs]

jondc9

Surface position is a basic term relating to where the actuator/panel is relative to its datum. A DFDR will record that position. If that part of the structure has fallen off, then it may prove quite hard to record where it is. I would also imagine that the relevant actuators that move the surface would be at least damaged, if not deatched with the said rudder panel?!

[arcniz]

Bubbers said :
If my theory is correct about the vertical stab failing initially from the front then the rudder inputs by Sten were probably to correct the stab causing the yaw. He was only trying to maintain heading so multiple reverse inputs would be what any pilot would do if the stab was causing severe yaw problems. If you were the captain would you let him thrash the plane around for a common wake turbulence event? I don't think so. Any flight attendant in the back would be severely injured if she was out of her seat for some reason. We all deal with wake turbulence and it is not an emergency, we just have to make that PA explaining how it is like being behind another boat to calm nervous passengers. A lot of politics was in that NTSB final findings.


Any suststained contact with contemporary systems of "Law" and "Justice" will reveal they, like "legislation" are quite similar to sausage-making: First grind the source material (facts and information) into barely recognisable fragments, add some seasoning, then pack the results into the desired container (official conclusion). Selection of facts for particular emphasis, inclusion or exclusion of details that support a certain case, even the sequence of presentation and reveal of known information can be massaged to finesse a leaning of meaning in a particular inclination, eventually supporting the conclusion of choice. If the goal is to find truth, then it may be found. If the goal is to conceal truth, then it will be concealed for sure.

If I recall (someone please correct me if wrong - the facts are complex and memory sometimes imperfect late at night), the most important top-level conclusion in the NTSB analysis is that the pilot flying actively and frequently reversed the rudder direction using the pedals. More important, this concept is not had from source data showing his pedal position, but is derived from low-fidelity heavily filtered FDR data on the recording track obtained from the rudder position sensor. Assumed is the premise that the only active cause for changes in position sensor data was the movements of the rudder pedals. The analysis is, therefore, inferring the cause from a partially suspect and very imperfect report of the result - and from this inference is built a framework of cause-effect relationshps using assumptions about how and why the pedals traveled to cause the rudder to move.

The entire analysis is a cascade of suppositions designed to support the final conclusion, heavily reliant on selection of salient facts, including critical facts prepared and information provided (and not provided) by EADS-Airbus, an interested party with immense financial exposure hanging on the outcome.

Not reported but also highly pertinent is the truth that the accident occurs and the final analysis is later put forward in a period of political instability and military concern, when censorship and misinformation from the same government that employs the NTSB are reaching a crescendo in support of perceived strategic imperatives for dealing with some external threats.

The process of requiring full disclosure regarding conflicts of interest is increasingly put upon businessmen and political candidates. Why not also apply this to the bureaucrats? Perhaps in some more enlightened future time, "impartial" reports such as this one could include a soul-searching summary of "External Factors possibly affecting analysis and conclusions in the Final Report".

Suggestions will be welcome for additional reasons why NTSB dropped the ball regarding AA587.

[Another Number]

FWIW, my initial - non conspiratorial - take on the events is:

The pilot's training regime was poorly thought-out in parts. The aspects relating to handling wake turbulence appear to exaggerate the effects, and encourage the pilot to respond quicker and harder than necessary.

This is coupled with unclear/misguided directions wrt rudder, and some missunderstanding.

The effects of the actual wake turbulence, which are impossible to accurately recreate may have been coincidentally reinforcing...

I'm no expert on wake turbulence, but, for the sake of imagery, imagine a boat encountering waves (parallel rather than perpendicular to travel) - the immediate effect is in one direction, then cresting the wave, in the other. If the pilot has commenced reacting to the first input, the second could reinforce the correction. If this was then followed by a second larger "wave", then the harmonics/sympathetic response would be significantly increased.


In such a scenario, once the pilot is preoccupied with the rudder and unexpected feedbacks, would such an outcome not be possible?


Feel free to shoot this down in flames! I'll admit I've only briefly looked over the report, etc.

[misd-agin]

Here's the report.

http://www.ntsb.gov/publictn/2004/AAR0404.pdf

The company didn't disagree that the FO used the rudders. The union investigator(s) didn't disagree that the FO used the rudders. Both of these parties had problems with the design and certification of the A300.

The union's crash investigative report detailed the design differences in rudder control. Only the newer Boeings (747/757/767/777) have the better design. Rudder travel is always the same, as is leg pressure. Other designs, 727/DC9/DC10/737/all Airbus models, have the system where rudder travel is reduced and the force required to get full deflection is reduced. The union's investigators pointed out that the A300 is significantly more sensitive than other designs.(NTSB agrees, page 146 of the report, pg 160 of the .pdf file)

At 250 kts the A300 rudder is 2X as sensitive as it as at 165 kts(most rudder applications x-wind, etc, are below this speed)(from NTSB report)

AAMP did not advocate large rudder inputs(several references to this in testimony, ie pg 86-pg100 of .pdf) (read NTSB report starting on page 80, pg 94 of .pdf).

Airbus stated the full use of controls may be necessary to control the a/c. And said to use alternating rudder inputs in the checklist for gear extension problems. It wasn't until AFTER the crash they published rudder recommendation in their FCOM manual.

Industry experts advised that all transport catagory a/c can generate loads, even below manuevering speed, that exceed design loads for rudder and stabilizer inputs. Caution is advised!

[misd-agin]

The result was an A300-600 design whose sensitivity increases with an increase in airspeed, unlike that of the B2/B4.
"We don't like the change in sensitivity from low speed to high speed," said John Clark, NTSB head of aviation accident investigations. "However, we don't know how far off the 240 knot point you need to be to have a safe system," he said, referring to the 0.02 G force imparted by pedal movement at that speed. "We want to buy more margin," he said, to reduce the potential for aircraft pilot coupling (APC).
APC is a phenomenon in which pilot control inputs can be out of phase with the airplane's reaction, tending to negatively reinforce an increasing deviation from desired to actual aircraft response. In the case of the Flight 587 accident, APC may well have been involved in the rapid series of rudder reversals leading to fin separation. Prior to the Flight 587 accident, few pilots were aware that APC was possible within the rudder circuit (i.e., around the yawing axis). Classic APCs have tended to be in pitch, with a minor number seen as instability around the fore-aft axis and known as roll-coupling. APC involves an involuntary interaction. The nature of the APC beast is that once the process is set in train, it is unlikely that any pilot will suddenly "get off" the controls. Disengagement is not intuitive.
Brenner, an NTSB human performance specialist, said, "APC events always reflect some underlying design characteristic."
"Staff concludes that the A300-600 is susceptible to potentially hazardous coupling at high airspeeds," Brenner said.
Magladry added that the pedal stop "is a moving target" that also depends on the functioning of the yaw damper.
While the board issued recommendations in early 2002 for pilots to be cautioned in training about the dangerous potential for rudder reversals (see ASW, Feb. 18, 2002), Vice Chairman Rosenker said, "At this point, we haven't done much about the rudder - its sensitivity."
Board Member Debbie Hersman said, "The sensitivity is more important than the AAMP program."

[Graybeard]

Here's a curve that maybe wasn't considered before:

The HF antenna and antenna couplers are in the leading edge of the vertical fin in most modern transport aircraft. It is a shunt antenna which is fed by the coupler that converts transmit power up to 400 watts at 50 ohms impedance to very low impedance - on the order of ten milli-ohms. The current, therefore, is very high, and it is carried a short distance from the coupler to the vertical fin on a heavy copper cable. The coupler excites the fin and makes the whole airplane into the antenna, meaning that very high currents are flowing in the vertical fin and its junction with the fuselage.

Now I know very little about the construction of the vertical fin in the A-310, other than it's a composite structure - carbon fiber? Is it possible that high currents, coupled with other defects could have damaged the attach of the fin to fuselage? If such damage were caused, it would surely have had to occur over a period of time.

We know, of course, that AA 587 would not have been transmitting on HF at that time, but do we know if this plane had a recent history of HF squawks?

GB

[misd-agin]

oops, previous post, and this post, from -


http://www.iasa.com.au/folders/Safety_Issues/RiskManagement/crowinstability.html
The Difference Between Certification Standards & The Real World

NTSB Member Debbie Hersman: If you are a line pilot, how likely would it be that you would get the full amount [of rudder]? Or get 1.2 inches of the pedal at 250 [knots airspeed]?
NTSB professional staff member David Ivey: If I were to put in rudder? And knowing what I had found that ... there was a very good chance you could put in full rudder [with 1.2 inches of travel]?
Hersman: And if you put in full rudder to the right, how likely is it that you're going to have to come back with the left rudder?
Ivey: I think I could speak for most pilots that if I had any input that had sent me to the right, for example, I'm not going to do what certification says and put my rudder to neutral. I am going to counter the effects that I have just experienced in my body or what I have seen and I'm going to put in opposite rudder to try to correct the problem ... But to answer your question, if I had a big yaw to the right I would put in left rudder. I certainly wouldn't put it in neutral.
Hersman: And once that happened, is it your belief that this pilot was in an APC?
Ivey: It is my belief. Source: NTSB

[misd-agin]

http://www.ntsb.gov/publictn/2004/AAR0404.pdf

NTSB AA587 final report

http://ntsb.gov/Events/2001/AA587/default.htm

bascially a table of contents

http://ntsb.gov/Events/2001/AA587/board_mtg_anim.htm

animation of flight path and another with control inputs.

[Graybeard]

One more observation:

The NTSB, and especially the FAA, will rarely identify a serious problem until there is a solution available. They really didn't want to ground every 737 in the world indefinitely, as they did the DC-10 in 1979.

By the time the 737 yaw damper problem was conceded, Boeing had a retrofit fix, and a longer term fix for new 737s in the form of a new fail active rudder they needed for CAT IIIb, anyhow.

Planes with wing mounted engines may be a lttle more efficient than those with tail mounted engines, btw, but they require a much larger and more powerful rudder to fly on one engine. That magnifies the seriousness of a wayward rudder.

GB

[Shore Guy]

"Planes with wing mounted engines may be a lttle more efficient than those with tail mounted engines, btw, but they require a much larger and more powerful rudder to fly on one engine. That magnifies the seriousness of a wayward rudder." G.B.


......Absolutley true, and I think most training organiziations do not emphsize this enough. HUGE loads involved. Makes for more of a handfull of airplane in a crosswind also. When I did IOE, I always tried to give students a couple of crosswind landings (once again, something not normally emphasized in the sim).

[mutley320]

Just had a look at the flight path animation link posted by earlier poster.It,s a while since i've seen it but could someone explain the climb profile used?
IE: nose over/accelerate at 1000 ft. Flaps up.
I'm sure it's American airlines SOP,i've just never seen a profile like it.
Climb power 1500ft agl, accelerate 3000 agl. is all i can recall on many types in 22years.
Everyday is a schoolday though.
While i'm at it, the use of the word "kick" in relation to rudder use is a pet hate of mine. "push, rub, squeez" are closer to the required action(bar some fancy aerobatics in an aerobatic aircraft)
Even on the flight control check i try to encourage people to gently and smoothly move the rudder to the left, centre,pause for a fraction and then to the right. Not just for mechanical sympathy but bar sim checks it's the only chance you get to train your muscle memory in your legs as to the forces in the rudder.I know it's a ground check and the rudder is different in the air at different speeds, but it's something.

Without going too deep into the accident, it would appear that the rudder was used in an inappropriate way, that is full one way and then full the other. For a large transport category aircraft it looked like too much to me.
Like all major accidents in aviation we as a group learn something from it.
I think "use of rudder" and its limitations is now given more attention in training.

Finally, at this time of year, spare a thought for the families of the crew and passengers.

[misd-agin]

Std climb profile. Seen the same profile used by other U.S. domestic carriers.

Gets you clean (less gas), and leaving town faster(less time).

AAMP never advocated 'kicking' the rudder which is an unfortunate term others have used. The AAMP tape, referenced in the NTSB report, actually says to be careful using the rudder at low airspeed and high AOA. "Too much is actually the spin entry technique, isn't it?"(paraphrased)

[Zeke]

From an excerpt from the 777, "Use of Rudder on Transport Category Airplanes", in response to NTSB Recommendations.
Explain to Flight Crews that a full or nearly full rudder deflection in the opposite direction, or certain combinations of sideslip angle and opposite rudder deflection can result in potentially dangerous loads on the vertical stabilizer, even at speeds below the design maneuvering speed.
Response: Boeing airplanes are designed to withstand the structural loads generated by a full rudder input out to the airplane's maximum operating airspeed, Vmo/Mmo. Some Boeing airplanes meet these requirements out to the design dive speed. This means the structure has at least a 50% safety margin over the maximum load generated by this kind of maneuver. As previously mentioned, Boeing airplane vertical fins can also sustain loads if the rudder is rapidly returned to neutral from the over yaw sideslip or the rudder is fully reversed from a full steady state sideslip. Boeing airplanes are not designed to a requirement of full authority rudder reversals from an "over yaw" condition. Sequential full or nearly full authority rudder reversals may not be within the structural design limits of the airplane, even if the airspeed is below the design maneuvering speed. There are no Boeing Procedures that require this type of pilot input. It should also be pointed out that excessive structural loads may be generated in other areas of the airplane, such as engine struts, from this type of control input. In addition, large sideslip angles may cause engine surging at high power settings.
It is important to note that use of full rudder for control of engine failures and crosswind takeoffs and landings is well within the structural capability of the airplane.
AAMP never advocated 'kicking' the rudder which is an unfortunate term others have used. The AAMP tape, referenced in the NTSB report, actually says to be careful using the rudder at low airspeed and high AOA. "Too much is actually the spin entry technique, isn't it?"(paraphrased)
From the 777 manual
Boeing recommends that:
· Transport pilots should be made aware that certain prior experience or training in military, GA, or other non-transport aircraft that emphasizes use of rudder input as a means to maneuver in roll typically does not apply to transport aircraft or operations.
· Transport pilots should be made aware that certain prior experience or training in military, GA, or other non-transport aircraft types emphasizing the acceptability of unrestricted dynamic control application typically does not apply to transport aircraft or operations. Excessive structural loads can be achieved if the aircraft is maneuvered significantly different than what is recommended by the manufacturer or the operator's training program.
In simple pilot terms, the rudder in a large transport airplane is typically used for trim, engine failure, and crosswind takeoff and landing. Only under an extreme condition, such as loss of a flap, mid air collision, or where an airplane has pitched to a very high pitch attitude and a pushover or thrust change has already been unsuccessful, should careful rudder input in the direction of the desired roll be considered to induce a rolling maneuver to start the nose down or provide the desired bank angle. A rudder input is never the preferred initial response for events such as a wake vortex encounter, windshear encounter, or to reduce bank angle preceding an imminent stall recovery.
Seems AA does not agree with what even Boeing recommends.
And ..
Q. What pilot action should I take to recover when I encounter wake turbulence?
A- Normal piloting actions for roll control are sufficient for large commercial jet transports. If a roll off does occur, the normal use of ailerons and spoilers should be sufficient to recover. The use of rudder is not recommended.
The induced roll from the vortex will be more severe for short span airplanes (relative to the aircraft that generated the vortex) but the recovery procedures are the same. Crews should perform the upset recovery procedures if bank angles of greater than 45 degrees are encountered.

[bomarc]

I think one thing we might all agree upon is this:

Insufficient information to the pilots regarding the possibility of rudder induced structural breakup was NOT part of either the Airline training program or the Flight Manual. Both approved by the FAA.

We might also wish to include in future FAA ATP written examinations a question concerning rudder induced structural breakup.

There have been other crashes where information existed in one location but not in another.

I am reminded of an F28 crash due to ice/frost on wings in Canada, only to be followed by a crash at New York's LaGuardia airport of another F28 due to ice/frost on wings.

Sharing information in the civil sector is vital.

[aardvark2zz]

Here's a curve that maybe wasn't considered before:

The HF antenna and antenna couplers are in the leading edge of the vertical fin in most modern transport aircraft. It is a shunt antenna which is fed by the coupler that converts transmit power up to 400 watts at 50 ohms impedance to very low impedance - on the order of ten milli-ohms. The current, therefore, is very high, and it is carried a short distance from the coupler to the vertical fin on a heavy copper cable. The coupler excites the fin and makes the whole airplane into the antenna, meaning that very high currents are flowing in the vertical fin and its junction with the fuselage.......

It's 0 ohms near 0 Hz (DC) but once you get to a few hundred KHz the impedance is much higher. Don't forget that you have real and inductive impedance which 'add' up. 400W into 50 ohms is only 2.8A rms.

[Graybeard]

It's 0 ohms near 0 Hz (DC) but once you get to a few hundred KHz the impedance is much higher. Don't forget that you have real and inductive impedance which 'add' up. 400W into 50 ohms is only 2.8A rms.
Maybe you've never seen the battery cable sized conductor from the center conductor of the coupler mount to the tail structure. That wouldn't be needed if the currents were low. The purpose of the current-fed antenna coupler is to convert 50 ohm impedance signal to near zero ohms - at operating frequency. That means currents up to hundreds of amps. And, yes, the carbon in a carbon fiber structure can mean mischief.

The HF system was undoubtedly thoroughly tested at A/B, but how about with all the combinations of degraded bonding?

BTW, what is 'real' impedance?
GB

[ssg]

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested. What about windshear, wake turbulence, flying over smoke stacks, through the tops of some small cell, all could impose way more loads then just shoving the rudder over......

Is it possible a pilot could yank and bank a plane apart, sure, but with the captain sitting right next to him? On take off?

Funny no one is talking about composites, inability to test them at the time, ect.

Food for thought....

[bubbers44]

Sten went to max power in an escape maneuver before the last breakup of the airplane. when control was lost. He would not have done this at that speed of 250 knots unless all other methods of controlling the aircraft had failed with the captains concurrence. Hopefully some day he will be found not responsible for this accident but Airbus and others want to leave the probable cause just as it is, pilot error. No cost.

[bubbers44]

Remember, that aircraft had a delaminated vertical stab that was repaired with staples and the break was parallel with the staples holding the stab together. Seems a lot like holding a sheet of plastic in a vice and guess where it breaks? Parallel to the vice jaws where it flexes. That is how the new aircraft was delivered to American when it was new. Unfortunately Sten had to fly it when it flexed a few thousand times.

[DozyWannabe]

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested. What about windshear, wake turbulence, flying over smoke stacks, through the tops of some small cell, all could impose way more loads then just shoving the rudder over......
Is it possible a pilot could yank and bank a plane apart, sure, but with the captain sitting right next to him? On take off?
Funny no one is talking about composites, inability to test them at the time, ect.
But it was more than just a rudder over, ssg. It was repeated contrary motions, in a sideslip, following a wake turbulence event. I don't think anyone would risk flight testing that situation knowing what we now know about it.

If the jury was out on composites, and it was obvious that Airbus made a mistake in using them, there's no way that Boeing would be risking their future by building their next big project completely out of them - at least, one would hope not.

It's in the nature of people to defend their own in such situations, and if the findings were as cut and dried as blaming the pilot for overcontrolling then I could understand the desire to dig deeper. But it's not that cut and dried, is it? There was a training culture that was too all-encompassing when it came to the type being flown - contributory cause number one. There was a bulletin that was disregarded regarding use of rudder in upset recovery - contributory cause number two. There was a pilot who, while doing as he was apparently trained, overcontrolled the aircraft and overloaded the tail - contributory cause number three. No-one is (or more precisely should be) blaming Sten Molin for what he did, which was by most accounts exactly what he was told to do. I hate to say never, but I doubt that the captain was monitoring his rudder inputs at the time - there simply wasn't the time to figure such things out. The system failed the people on that aircraft and the system has since been changed. There are those that want to blame Airbus and there are even those that insist that there was an act of terror involved. None of this is helping our skies be safer.

[bubbers44]

The captain always monitors unusual control inputs by the copilot. Those inputs would have probably killed a standing flight attendant in the back who got up to take care of a passenger in distress right after takeoff. I do not think you could put enough rudder into an A300 to rip the engines off. The vertical stab must have done it. It probably was separating from the aircraft causing the gyroscopic forces on the engines to make them separate from the aircraft. Wake turbulence normally does not cause much yaw and is easily corrected by aileron. Has there ever been a wake turbulence upset causing extreme yaw? I have never encountered one.

[TowerDog]

I'm sure it's American airlines SOP,i've just never seen a profile like it.
Climb power 1500ft agl, accelerate 3000 agl. is all i can recall on many types in 22years.


That would be Noise Abatement Climb profile.
Quite a few US companies go for clean machine at 1000' unless a Noise Abatment profile is called for.

As for the topic on hand:
I have been through the AA course recovering from unusal attitudes. There was nothing there about slamming the rudder from side to side, but rather using "top" rudder to help bring the nose around...If needed.

Keep in mind the A-300-600 that crashed had the vertical tail damaged at the Airbus factory before delivery to AA.

Perhaps a factor in the accident....? :confused:

[INLAK]

Having flown with African, Asian, Australian, European and American pilots, I found a very noticable enthusiasm to use the rudder from the Americans only. Maybe it's all down to training.

[Mad (Flt) Scientist]

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested.

I am frankly astonished that after all the warnings which were issued after this accident, regarding the potentially catastrophic effect of large rudder inputs AT SPEED EVEN BELOW VA, that anyone could dismiss the idea that rudder inputs could overload a transport category aircraft with such disdain.

Every single Part 25 aircraft with conventional flight controls (i.e. disregarding those with envelope protection) can undoubtedly be brought to the point of inflight break-up by means of flight control applications, even at speeds comparable to this accident. The only differentiation between types is the degree of input (or number of inputs) required, and the associated cockpit forces. But they WILL all do it.

In fact, any aircraft claiming to be resilient to such inputs is in fact BADLY designed, because there was - and still is! - NO certification design requirement to withstand such inputs. And I suspect there never will be; it's not the intent of the regulations to specify a pilot-proof aircraft, simply one that can be operated safely if trained accordingly.

[DozyWannabe]

I do not think you could put enough rudder into an A300 to rip the engines off. The vertical stab must have done it. It probably was separating from the aircraft causing the gyroscopic forces on the engines to make them separate from the aircraft. Wake turbulence normally does not cause much yaw and is easily corrected by aileron. Has there ever been a wake turbulence upset causing extreme yaw? I have never encountered one.
What you're describing are the precise conclusions of the investigations - the rudder reversal induced vertical stab separation, which induced yaw and spin, which induced engine separation.

Keep in mind the A-300-600 that crashed had the vertical tail damaged at the Airbus factory before delivery to AA.
Perhaps a factor in the accident....? :confused:
Got a link handy for that? 'Tis the first I've heard of it. I think there was some disbonding, but that was unrelated to the failure and could be considered normal wear and tear.

[hetfield]

Having flown with African, Asian, Australian, European and American pilots, I found a very noticable enthusiasm to use the rudder from the Americans only. Maybe it's all down to training.

Yeah, I fully agree with you. When I started flying on a Bonanza, my instructers (all of them american) made comments about that bungee which operated (within certain limits) the rudder without pedal inputs........

[Slats One]

Having just spent a long time researching composite construction, I want to throw an unpopular theme into the debate.

Even if we put aside that this aircraft was flying with a manufacturing "cure" fault repaired, there is now surely enough hard evidence - ie the Transat rudder disintergration etc, to now conjecture if there is another reason why the handling pilot was pumping the rudder pedals?

We have been asked to accept that pilot's behaviour, the AA advanced handling training, etc, were the fulcrum behind the handling pilot's response to a wake turbulence induced issue - which then led to the empenage snapping off as a consequence of pilot induced oscilations.

Sorry folks, I no longer buy it. What if the reason the rudder pedals were being pumped was because (a la Transat event) the rudder had begun to disintergrate and detach - resulting in aerodynamic instability - leading to reactive pedal inputs - which are then erroneously blamed as a pilot error cause.

If you doubt the possibility of this potential scenario- go an examine the Transat investigations. You will find that not only did the rudder break up and tear off, it also almost severed the main fin mountings-one side had already begun to tear. It becomes obvious that if the Transat crew had reacted by pumping the pedals, the process would have been completed and another Airbus lost. But they were in the cruise not maneuvering a climb out form JFK.

And all this is without discussing the fitting of one tail design to range of fuselages with differing levels of thrust, polar inertia and airflow. Let alone ageing composites, manufacturing errors and repairs across the entire marque and the mulitple ADs issued about such. Throw in hydrualic actuattor leaks effecting bonding and lamination and electrical effects an you do not even begin to make a 'knock' test of the structure an effective tool.

Sorry folks, but I am not alone in worrying about the ease with which pilot error is being used to smother the very real issues of composites and how Airbus has chosen to use them. And no this is not an anti- Toulouse rant. Its careful factual analysis of a pattern of dysfunction within the design.

Speculation is dangerous, but a repeated pattern of events requires further investigation.

[misd-agin]

What you're describing are the precise conclusions of the investigations - the rudder reversal induced vertical stab separation, which induced yaw and spin, which induced engine separation.


Got a link handy for that? 'Tis the first I've heard of it. I think there was some disbonding, but that was unrelated to the failure and could be considered normal wear and tear.

Find the crash photos from AA 587 and look at the pictures that show the tail. One segment of the tail is still attached to the fuselage lug attachements. That segment is the patch installed by Airbus to correct some production damage(incurred while installing the tail???). The patch was stronger than the rest of the tail.

Design failure is 2.00 design load(incorrect terminology). Failure occured very, very close to 2.00(+/-.3 I believe).

[JustAnothrWindScreen]

Yep, this program filtered down to the other airlines. I was given a version of the training that included the hard rudder kicks to get the nose back down to the horizon in some attitudes. I questioned whether you really wanted to do this in a transport aircraft but was told that it was all within the design envelope. I guess it turns out that it wasn't...

I went through the AA program and it did not include hard rudder kicks for any maneuver. It did however include smooth coordinated rudder when necessary. .

[bomarc]

slats 1

I think you are right

[bubbers44]

Slats one, I have always thought your feeling that he was reacting to the aircraft yawing because the vertical stab or rudder was failing was correct. Did they study if the rudder inputs were before or after the aircraft yawed? I believe I read that the actuators on the rudder sends signals to the flight recorder, not the rudder pedals.

[Jurassic Jet]

Thank you Slats One.

I have long held that there are only 2 pilots who know what it feels like to have the tail come apart on an Airbus and they are both dead.

The NTSB has only 2 kinds of accident findings:

1. Pilot error and the guilty pilot is alive.
2. Pilot error and the guilty pilot is dead.

587 is the latter.

During the investigation of the 587 crash, President Bush was trying to form coalition to fight the GWOT. Whatever else it is, the NTSB is a political animal.

There were 3 things in play during the NTSB investigation into this crash.

1. Politics – The US didn’t need to upset the EU by finding Airbus at fault for manufacturing or certification reasons, thereafter causing the grounding of an entire fleet, perhaps worldwide.

2. Money – The NTSB didn’t want to frighten any more customers away. The US airline industry advance bookings after 911 we non-existent.

3. Pilots – What did the guilty bast@rd(s) do wrong?

Who do we think is going to win that battle? If you think it’s the pilots, go to the rear of the line. Politics and money trump pilots every time in any NTSB investigation.

So the easy fix was to blame a dead pilot. No political ramifications, very minor economic ramifications and one dead pilot who can’t tell what really happened.

Over and out, as far as the NTSB is concerned.

[Slats One]

Glad I am not alone. I do not do conspiracy theories, but the trail of events post this crash is begining to look iffy.

One other point, they found the tail fin minus the rudder -has anyone determined if the rudder came off after the fin snapped - ie as the rudder fell, or did the rudder come off prior to fin failure?

Given that the rudder is not attached to the fuselage -but to the fin - surely it's point that should be answered-ie which wagged the dog first?

As far as I am aware, there is has been no debate as to why the fin was found minus the rudder and when did the rudder come off that fin?

If you study the CVR tape it is very clear that before the application of full power -and before the sound of what might be the fin coming off. there is clearly a handling issue apparent- with reactive process from the PIC and left seater (verbal inputs). What casued that handling issues- was it relly just wake turbulence and pilot input. I doubt it.

(And if it was, that means that the generic tail design as fitted across a range of aircraft is now suspect - an entirely separate issue based on the acceptance of the NTSB findings -not the questioning of it some of now make..)

The political and financial issues as cited are of course relevant -but are not to me the fulcrum. The fulcrum- the point of the thing is that rudder and subsequent events to several aircraft - notably Transat - have not been adequately invesitgted at teh time or consequent to further events.

Nevile Shute and Ernie Gann would have worked on this one.

After careful consideration, I now doubt the accepted NTSB version of events: clearly I am not alone. The AA 587 pax and crew desrve the truth - whatever the ramifications... Time will tell.

[misd-agin]

Spent the morning going over the AAMP tapes. Dated 19 Dec 1997. Training for the CA on AAMP was in May 1997 with sim training 1997(tape presentation was from March/April 1997-NTSB report pg 85 - pg 99 out of 212 pdf file) so

It's an excellent presentation. I'm no fan of the presenter but his briefing is on target. It's about operations at the edge of the flight envelope to save a/c and is about typical line operations. Discussion centers on the to roll the a/c from nose high attitudes and the ability to use the rudder if necessary.

He refers to rudder use several times and it's always 'coordinated', 'smoothly', 'these are powerful rudders so use small amounts', 'I never said to use opposite rudders', 'if you want to use a little rudder go ahead', etc, etc.

http://www.ntsb.gov/publictn/2004/AAR0404.pdf

The NTSB report deals with the AAMP on pages 80 (pg 94 of pdf) Sec. 1.17.1.2 until pg 95 (pg 109 of pdf)

Page 95, (pg 109 of pdf) Sec. 1.17.2.2.1 has Airbus' discussion of the use of rudder. The difference between what Vandenburg's entire presenation, and Airbus' position, is trivial. Airbus had concerns about Vandenburg's comment to use 'rudder in the direction you want to roll'. I thought 'uh oh' when I saw that part of the tape. But when Vandenburg's total presentation is viewed the one sentence being called into question is nit picking. The total presentation mentions several times the limited use, coordinated, small, and careful use of rudder. And, to satisfy the manufacturers concerns, at the end of the tape he mentions the limitations to rudder use again(NTSB report).

If you can't view the AAMP tapes at least read the report. AAMP is still taught at AA training. The briefing by CA Vandenburg is still valid.

And even a non professional pilot on the NTSB gets it (previously posted quote) -

While the board issued recommendations in early 2002 for pilots to be cautioned in training about the dangerous potential for rudder reversals (see ASW, Feb. 18, 2002), Vice Chairman Rosenker said, "At this point, we haven't done much about the rudder - its sensitivity."
Board Member Debbie Hersman said, "The sensitivity is more important than the AAMP program."

The A300 rudder is the most sensitive rudder out there.

And the investigaton shows that the plane moved in response to the rudder inputs as opposed to side loads generating first followed rudder inputs to stop the unintended yawing moments.

As Mad(flt)scientist said, any commercial a/c not protected by computer flight laws can generate these loads. That folks argue or doubt this today is scary.

[misd-agin]

If you study the CVR tape it is very clear that before the application of full power -and before the sound of what might be the fin coming off. there is clearly a handling issue apparent- with reactive process from the PIC and left seater (verbal inputs). What casued that handling issues- was it relly just wake turbulence and pilot input. I doubt it.



I had the luxury of talking with someone who knew about folks reactions from when they flew the accident profile in a NASA sim.. Said folks were sceptical of blaming the rudder inputs for the crash. Problem is typical simulators don't do an accurate job of simulating the side loads. The NASA simulator does a better, if not great, job of simulating side loads.

Simulation timeline is running - "Ok, little bit of turbulence...first rudder input now... WOW *HIT! Folks were stunned by the side load generated.(try flying with a G meter and putting a 1/4 or larger G load on the a/c quickly. Now make that a side load. I was told it was very abrupt).

I was told this is when (some?) folks realized it might have been a rudder PIO. This is the rudder sensitivity the NTSB board discussed.

[misd-agin]

Slats one, I have always thought your feeling that he was reacting to the aircraft yawing because the vertical stab or rudder was failing was correct. Did they study if the rudder inputs were before or after the aircraft yawed? I believe I read that the actuators on the rudder sends signals to the flight recorder, not the rudder pedals.


http://ntsb.gov/Events/2001/AA587/board_mtg_anim.htm

"Flight Path Animation" shows relationship between rudder position and lateral loads so yes, they did study that.

3 rudder swings in 3-4 seconds, followed by full right rudder for two seconds, followed by 2 more rudder swings in two seconds. It's at the end of this 7-8 second timeframe, that included 5 full rudder movements, where data acquisition from the rudder position failed(fin departed).

[AirRabbit]

Hey … guys … ! I am not a dyed-in-the-wool, NTSB fan (as I DO think they make their share of mistakes, like every human being), but I think they got this one right. Everyone here seems to be trying to attribute a single cause to a very complex series of events that resulted in a huge tragedy. THAT simply isn’t going to happen. Those of you who have been involved in aviation for a reasonable period of time should easily recognize that any story is going to have multiple parts – some good, and some not-so-good. That is true here as well.

Those of you who believe the F/O of AA587 was prematurely taken to the woodshed because he is no longer here to defend himself – are partially correct … but only partially. He WAS at the controls. Therefore, he has to bear the responsibility for the control input … but, before you dismiss me out-of-hand, I think he had plenty of help in getting to the accident site.

Those of you who believe it was the faulty, composite aircraft assembly, you may have some legitimacy in your concerns, but none of it has been proven. So, I’m afraid you’ll just have to hold on to your theories for a while.

Those of you who believe it was the faulty design of this particular aircraft, DO have some legitimacy in your concerns – but only some. Read below.
Those of you who believe that it was AA training that should absorb the brunt of the “fault” also have some legitimacy – but, you too, get only some legitimacy.

Those of you who believe that it was Air Traffic’s fault, clearing AA for takeoff too closely behind the heavy JAL B-747 … unfortunately, your concerns get only “honorable mention,” because, while encountering wake turbulence was involved and (I think) was the initiating catalyst, it did NOT cause the accident.

Here is a link to an animation derived from the Flight Data Recorder that shows an animation of the aircraft (although that isn’t the most interesting part, in my opinion), the time, altitude, airspeed, attitude indication, control wheel position (roll control position and pitch control position), vertical acceleration, rudder pedal position (L/R deflection), rudder surface position (also L/R deflection), lateral acceleration and a top-down view animation of the vertical fin/rudder position.

http://www.ntsb.gov/Events/2001/AA587/flight_path_web01.wmv

In this particular circumstance, the airplane is known to have a very sensitive rudder control input system – and one that gets a maximum rudder deflection, not only lighter in feel than other airplanes, but also with a lot less pedal travel required to get a greater amount of control surface deflection. Specifics? The A300-600 rudder is hydraulically actuated with no direct feedback to the pilot. There is no “air load” on the control surface that the pilot can “feel,” so the system is built to provide and artificial “feel.” By way of comparison, a B-767 (a similar sized airplane) at 250 knots has a breakout force of 17 pounds-feet (force necessary to begin movement) and the pilot would need to generate 80 pounds-feet to achieve maximum displacement – which in the B-767, is a bit over 3 and a half inches of rudder pedal travel and 8 degrees of rudder surface deflection. The A-300-600 is noticeably different. With the same circumstances, the pilot has to use 22 pounds-feet to start the movement (breakout force) and 32 pounds-feet to get maximum rudder pedal travel (about 1.2 inches) and maximum rudder surface deflection (9.3 degrees). The math here says that the A-300 is over 7 times as sensitive as the B-767; or, said another way, the amount of rudder actually deflected for each pound of force on the rudder pedal above the breakout force is almost 9 times as much in the A-300 as in the B-767.

We might have had a pilot who was “spring-loaded” to the use of rudder. Specifics? There is the report from other pilots who had flown with this first officer who have said that, in their opinion, he “used the rudder too much.” Now, I certainly don’t know what that means, but, when you combine that statement with a careful review of the FDR animation video, it’s hard not to notice how quickly and how much the rudder was used in this case.

We might have had a training program that instilled in this pilot the idea that the rudder is an effective tool to assist in controlling the airplane. Specifics? While not specifically “damning” in its content (my information is that the specifics in the training program regularly use the terms “smooth,” “coordinated,” “use small amounts,” etc.), the American “Advanced Maneuver Training” course did advocate the use of rudder in recovering from unusual attitudes; and this is not the only instance where an American crew used the rudder (as they were trained to do) in a circumstance that resulted in a flight condition that got the NTSB’s attention.

We had a pilot that, at least to me, appeared to be spring loaded to the “I’d-better-get-into-the-controls-quickly-to-prevent-from-happening-what-I-don’t-want-to-have-happen” position. Specifics? Careful observation of the FDR animation shows almost immediate and rather significant rudder pedal and rudder surface deflection at the very outset of the second set of turbulence encounters – which appear to be applied prior to aircraft displacement. You will have to view the video and make your own determination.

We had a pilot that probably was not aware of the problems that multiple control input and reversals could cause. Specifics? Shoot, there are still pilots on the line who either don’t know, or are skeptical of the fact, that multiple, commanded rudder reversals with an airspeed below Design Maneuvering speed can cause significant airframe damage. Although, with all this publicity, I can’t imagine too many pilots not knowing of this particular accident and its various points and counter-points for very long!

We had a flight that took off relatively close (although probably within legal limits) behind a very heavy, very slow airplane that is known to generate a ton of wing tip vortices, and followed the same departure flight path – below and behind – precisely where wing tip vortices like to live. Specifics? I think this can easily be determined with a review of the CVR tapes and tower and ATC observations.

We had a pilot that probably found himself in a PIO and didn’t know how to correct for it. Specifics? Again, I would refer you to the FDR animation – and again, believe that you will have to determine the accuracy of this statement for yourself.

Also, the comparisons between this accident and the two accidents involving B-737s (for which Boeing has since developed and deployed a “fix” and new procedures) are not valid – as these two circumstances heavily involved the phenomena of “cross-over” speeds vs. aircraft control that had no application to the AA587 accident.

[Slats One]

Airrabbit makes a very reasoned case - which should not be overlooked- its the growing snowball effect of course- all those differing factors building up on top of each other.

All i am trying show is that if you view the AA587 NTSB report with the knowledge of post -report subsequent events (ie Transat etc) it becomes clear that subsequent circumstances- had they been fact at the time of AA587, may, repeat may have created a different mindset.

I think the NTSB should perform a deep peer review of what they knew/know then and now- a la Rumsfeld's, known unknowns and unknown unknowns...

I have just looked again at some AA advanced training video- the lecturer is clearly using a T tailed twin jet- Fokker 100 or MD series (?) He advocates use of top rudder to stop the nose falling down (he demonstrates such nose fall). But he never tells anyone to kick it their.

And those baby T tailers are very different beasts - we all know that...

I am still at a loss as to which came first on the AA 587 - the tail wagging the pilot or vice versa- but I now believe that their are enough subsequent events to suggest a review of the finding that it was the pilot- so far promulgated.

Its not what happend its why- but what if the why was because of the what-the unconsidered what at the time (but since highlighted by events)

The rear cabin on AA857 must have been twanging around like a circus ride - how come no commander intervention - how come no thinking about who or what was causing the swing - pedal or fin/ rudder- which happened first.

If we had not had Transat etc since- all this could be dismissed as speculative dross. but it is not - not any more -not now we know what we know...

The arguement that this had not happened before so it cannot be the aircraft is bunkum- becasue that ignores the issue of teh ageing composite - about which even my professor of composites friend says " we know so very little - except from the experiecne of heat and cold soak and chemcial degredation on yachts..."

As I said, its classic Nevile Shute stuff..

Its time others typed, fly safe...

[RatherBeFlying]

Using AirRabbit's numbers for 250 kt:
Type.. B-767 A-300-600
Brkout 17 .... 22
Max... 80 .... 32
Travel 3.5 .....1.2
Max/
Brkout 4.7 ....1.4

I am led to suspect that any attempt to use rudder on the A-300-600 at 250 kt. is highly likely to get maximum rudder:uhoh:

If you looking for an APC/PIO trigger, it's hard to beat this one.

[Jurassic Jet]

No conspiracy thoughts here either.

In my opinion, it's more like the NTSB decided to ignore Ockham’s Razor.


587 crashed because the rudder failed causing the vertical fin to fail which caused the airplane to crash.

587 crashed because the rudder failed causing the vertical fin to fail because the first officer made excessive and abrupt rudder inputs, which caused the airplane to crash.The finding of pilot error is just the simplest, cheapest and most expedient way to end the investigation. That it also resolved the political and money problems was just icing on the cake.

JJ

[AirRabbit]

Again - take a look at the link provided with special attention to two areas on the video. The first is between 15:35 - 15:45 (the first wake turbulence encounter) and notice the exclusive aileron control applications in response. The second starts at 15:51 and runs to the end (the second wake turbulence encounter) and notice the aileron, elevator, and rudder applications in response. Notice when they start, how much control input was used each time, and how frequently and how quickly these control applications were reversed.

Here's the link again:
http://www.ntsb.gov/Events/2001/AA58...path_web01.wmv

[misd-agin]

Using AirRabbit's numbers for 250 kt:
Type.. B-767 A-300-600
Brkout 17 .... 22
Max... 80 .... 32
Travel 3.5 .....1.2
Max/
Brkout 4.7 ....1.4

I am led to suspect that any attempt to use rudder on the A-300-600 at 250 kt. is highly likely to get maximum rudder:uhoh:

If you looking for an APC/PIO trigger, it's hard to beat this one.

Story going around AA during the investigation was three pilots, Airbus, AA supvr, AA line pilot(union), were put in the sim for testing. All three were asked to apply half rudder at 250 kts.

Of course the AA pilot and the union pilot, if anyone, would be suspect to perhaps slightly overdo their input to support the incident crew. How about the Airbus pilot? No, he'd baby it, if anything, to show how simple using the rudder actually was.

All three applied something like 45 lbs +/-, resulting in full pedal deflection. And they knew in advance how sensitive the rudder is.

The rudder is normal at approach speeds, fine at 210 kts, and significantly more sensitive at 250 kts.

But the design of the A300 is similar to all the older designs except for the 747/757/767/777. I don't know how the A330/340/380 rudders operate. But as AirRabbit's posted data shows what sets the A300 apart from it's peers is the sensitivity of the rudder. 737/727/DC-9's etc. are not as sensitive with the same rudder design.

[Ignition Override]

The DC-9's pedal travel results in a direct, proportionate rudder response, whether powered by a bit of right system hydraulic pressure or (no hydr.)mechanically with the (unlocked) control tab, from what I've always studied.
And the tails have no graphite epoxy or other synthetic, plastic sort of parts.

DC-9s, still flying since 1965, or '72! And no cold-bonding process, as used in the B-737-200 upper fuselage...remember the tragic Aloha Airlines emergency descent, minus one flight attendant?

Why was the A-300 weight reduction in the vertical fin worth the risk of undetected fatigue deep inside the tail? Were not the forecast operating temperature extremes a new element?

[ironbutt57]

I.O sounds like a piece from SNL's old skit "and now a few words from and angry old may" culminating with the statement..."and thats they way it was..and we LIKED it", "and we'd do it again if we had to":ok:

[arcniz]

Damn Right. They don' makem like they usta. No heft. Can't hammer 'em back into shape when something gits bent.

Take it to mind, tho - Progress doesn't always move us forward.

[jeff748]

...Like the Comet.:}

[WorkingHard]

"Like the Comet" did not Boeing benefit from the tremendous research that went on to find why the Comets failed and used the results accordingly? Have yet to see any USA built airliners exceed mach1. Is the VC10 not still the fastest sub-sonic airliner ever built?
Not biased but just wanted to set the record straight.

[bomarc]

dear working hard:
just to set the record straight, both the DC8 and DC9 were taken to mach 1.0+ during tests...neither had rudder problems.(not that the subject referenced rudder)

as to the others speaking ill of the 737 and its rudder...consider that planes built now would have to have a different rudder system for certification...the airbus is a much newer plane (even the A300) and should be better.

The VC10 is a lovely looking plane. I don't know the speed specs on it. but like the DC9, the rudder is quite small compared to the A300 or the 737. For reasons discussed on this thread before.

[Slats One]

The VC10 by the way, flew 3,000 hours at BOAC and nearly 6,000 hours at the RAF with an early composite rudder (1 section of the 3 rudders on VC10) over the course of 3 years. No problems were encountered and along with other trials (like the all composite HS125 wing) these 1970s experiments hastened the use of composites in aviation.

BUT no ageing tests across a decade of temp soak and chemical changes could have taken place in such short trials times. Which again takes me back to my early post- the fact of the ageing composite. Such phenomena is not as rapidly obvious as the Comet's meteal fatigue issues, but it exists.

I did some early work 25 years ago on trying to build an integral (not bolt in) sub-chassis from composite, within a composite skin structure - to create load/stress paths within the panel rather than just have the stuff 'creep' to its nearest weakness and shatter at random.

Yet to this day car makers and our european composite friends just mould a panel and glue or bolt in, composite and alloy reinforcements - which as you can see from the AA587 fin fracture history, does not maketh much sense.

Imagine a fiberglass car- much stronger/lighter than a steel one -but when it does break, it shatters at random and often where you least want it too.. Yachts are still the same.

Here endeth the lesson , but its all vital to the AA587 and subsequent failures - and to the forthcoming 787. I reckon there are lot of worried engineers out there on both sides of the pond...

[GlueBall]

(French) BEA comments on the NTSB report entitled:
"An Inquiry into Whether a Pilot-Induced oscillation was a factor in the crash of American Airlines Flight 587".

"...Regarding the general approach:
On section II, « PIO phenomenon », we have no comments on the veracity of what is presented. What may, however, lead to confusion is the choice of the examples and the definitions given.
This section presents a digest of what is known on the subject of PIO, but it should be emphasized that: The two examples selected (the C17 and the Space Shuttle) describe phenomena where the flight control used acts directly on the axis to be controlled (aileron/roll for the C17, control column/pitch for the Shuttle). The main difference with AA587 resides in the fact that, in the latter case, the pilot used rudder control inputs in an
attempt to control roll. The main identifiable cause of time delay between the control inputs and aircraft response is, in this case, the time delay to induce roll. This subject is, however, never examined in this study.
In the following section, a conclusion is reached through syllogism, based on the judgment that there is PIO and that this phenomenon is attributable to the sensitivity of the airplane.s flight controls. This short cut fails to take into account induced roll, characteristic of rudder control, that is common to all transport airplanes in this category, which generates a time delay between the pilot.s control input and the response perceived. The Airbus simulation on the relation between PIO on the roll axis and the sensitivity of the controls appears to show that even a light rudder pedal input may create a divergent output. This system remains stable simply by using the control wheel with high gain.

As far as we know, no studies have been undertaken on PIO on the yaw axis since the rudder is not a primary flight control. It therefore seems important to treat this problem in a global manner, without omitting any elements. The definition of sensitivity applied in this report for the purpose of comparing the
A300-600 with other transport aircraft marks out the A300-600 without being
representative of the handling qualities of the airplane.
To summarize, hypothetical PIO can be considered to be caused by a time delay between the control input and the expected parameter. This time delay is the sum of different elements:

• Pilot response time, which can be broken down into perception time and
reaction time. It is commonly agreed that reaction time is about 0.2 seconds.
As regards perception time and time to analyze the perception, this can be
variable. In fact, this depends on factors relating to habituation. A trained pilot who knows the characteristics of the system well uses short cuts (Rasmussen model, « Skill Based Behavior »).
• The sensitivity of the flight controls, as mentioned in the report. There is,
however, a lack of factual data to characterize the sensitivity of A300-600
rudder pedals and, in general, data on PIO induced by rudder pedal inputs.
• Time delay due to saturation of the servo-controls. The speed of the servo-
controls is about 45°/s for the ailerons and 60°/s for the rudder. This should be compared with other systems.
• Time delay specific to the use of the rudder (induced roll, etc).
Consequently, the approach used in the report, which does not include all of these parameters, cannot be considered as complete. The complexity of these phenomena requires additional precautions to be taken in the presentation of the results.

Comments on section III:
III.B.1: Bearing in mind all of the reservations expressed on this report, it does not appear to us to be convincing to state that the PIO phenomenon has been clearly established just on the basis of observations made on oscillation frequencies. We note that following the first right open loop rudder input there was a first rudder doublet over a period of two seconds, stabilization for two seconds and then a second doublet over a period of two seconds. These observations do not lead to the conclusion that there is a cyclical phenomenon.
It is likely that the pilot reacted to unusual perceptions and that his actions in turn reinforced his perceptions. Given the complexity of the system, with reactions in all three axes, it seems to us difficult to make a simple judgment that the flight controls are implicated. Further, and in accordance with E. Cooper.s warning on the evaluation of an airplane.s handling qualities, only an evaluation carried out with a pilot would make it possible to draw any conclusions on the sensitivity of the flight controls:

At present the applicability of the mathematical analysis including representation of the human operator is restricted to the analysis of restricted task. Since the intended use (mission) is made up of several tasks and several modes of pilot-vehicle behavior, it is difficult first to describe accurately all modes analytically, and, second to integrate the quality in the separate tasks into a measure of overall quality for the intended use. "(G. E. Cooper NASA, the use of pilot rating in the evaluation of aircraft
handling qualities)
III.B.3: sensitivity was defined, by the human factors group, as "magnitude of aircraft motion in response to a given amount of rudder pedal force above the breakout force (simple measure = lateral acceleration in cockpit resulting from the yaw moment)". However, this report uses another definition of sensitivity "A300-600 rudder pedal is more sensitive than Boeing design if you compare the degrees of rudder commanded per pound of pedal force above breakout".
This new definition of sensitivity cannot be taken into account as a significant factor, since an airplane with different flight control surface dimensions may have identical sensitivity, even though the reactions felt may be very different. Comparisons with other manufacturers on this basis seem meaningless and inappropriate.
We do not agree with the physiological data described in this study. The size of a muscle has no influence on control sensitivity. Comparisons with helicopter yaw control and automobile brake control would serve to illustrate our point.
III.B.5.a The last phrase contains a short cut that does not satisfactorily establish the relation between rudder/pedal sensitivity and a longitudinal axis PIO. While it is true that uncoordinated actions on the roll and rudder controls may have disoriented the pilot, it is still not proven that the sensitivity of the rudder controls was the initial causal factor.
III.B.5.b The use of these results is surprising. Observations made on servo-control rate saturation can be applied to all aircraft. There is no aircraft on which the servo-controls respond instantaneously. This means that the time delay which is mentioned here is a general characteristic. It is, of course, necessary to take this into account in the study but it would be reasonable to include (as in table 1) the relative position of the A300-600 in relation to other airplanes in the same category and to add that the other airplanes have the same limitations. Thus the time delay which is mentioned for the time delay calculation would apply to any servo-control, and it is worth noting that this time delay is of the order of a half a second. In any case, it has not been proven, on the basis of the FDR parameters, that there was any saturation of the rudder, only of the ailerons.
Comments on section IV: The proposition that the pilot did not use the rudder/pedal implies no PIO does not mean that the sensitivity of the rudder/pedal implies PIO.
The preceding remarks and questions call into question the conclusion of this report. The only source of time delay accepted is the sensitivity of the rudder pedals. By omitting the time delay associated with the induced roll that develops when the pilot uses the rudder pedals, as well as the impact of pilot conditioning on the gain, the topic is examined only partially. It is thus difficult to use this document as it stands in the context of the analysis of this accident. It does, however, provide a springboard for questions that may lead to an understanding of this event...."

[Clandestino]

Regarding the issue of ageing composites, it seems that the composites within the tail of N14053 aged graciously because:

NASA's and Airbus' FEA models determined that failure of the rear main attachment lug was the most probable initial failure. The FEA models and NASA's PFA model also determined that the failure initiated at the final observed maximum vertical stabilizer root bending condition during the accident flight, when the vertical stabilizer was subjected to a global root bending moment of more than two times the value defined by the limit load design envelope. (As previously stated, for certification, the vertical stabilizer is only required to support loads of 1.5 times load limit without catastrophic failure.)


as stated on pages 68 and 69 of NTSB report. Couple of previous pages contain methods applied in analysys of fin and rudder. More of it is in other documents available within public docket. If you're still convinced that there was unprovoked delamination or that fin failure started from the front, please read the report and tell us exactly with which part you disagreee and why.

What difference would made if fin was metal instead of composite? Do you think that it would be beefed up to stand 3 times the load limit? Me not. This fin exceeded regulatory requirements by very healthy margin. Perhaps metal would bend before breaking, but that would be hardly helpful.

Accident investigation is not about approportioning the blame. Goal of accident investigation is to gain understanding of particular accident, so its reoccurence can be prevented. By listing F/O's rudder input as primary contributory cause, NTSB didn't say he was to blame or should get punished, just that he did so-and-so and consequences were such-and-such. Blame and punishment are best left for religious and judicial entities.

[rubik101]

That T no Sugar fellow is such a wheeze eh? Where did he come from I wonder, central casting for morons perhaps?
As an aside on this issue and I realise it is very unscentific, consider this if you will;
As you drive your car carefully around a slight bend on the icy road, you encounter a patch of ice which upsets your equilibrium; what do you do in response? a: Swing the wheel repeatedly and fully from side to side to try to regain control, or b: squeeze in a bit of into-skid wheel and reduce the power a little?
B gets you home, a gets you in the ditch. Quite simple really.

[barit1]

The skidding auto analogy doesn't really hold true, for in the auto there's the highly nonlinear control effect of traction vs no traction. That's why it's important to use the small counterintuitive wheel input to regain traction. (I always seek out an empty icy parking lot to practice this manuver at least once a year!) :ouch:
The large transport aircraft by contrast has a large yaw inertia, and a relatively linear rudder control system, but may be susceptible to Pilot-In-Loop oscillation in extreme cases. (We used to call it Pilot-Induced Oscillation, but today that's considered pejorative). Such oscillations have proven destructive on many occasions.

[RatherBeFlying]

BEA's reasoning in its commentary posted by GlueBall is viable as far as it goes.

But there is one giant piece of data missing from the report that left this opening for BEA; namely, a recreation of the accident scenario up to the first rudder pedal movement in the second 747 wake encounter-- definitely lets not do more than one.

If Airbus is that confident of its engineering, why did it not arrange for such a test?

[rubik101]

Barit1 says that the skidding car analogy doesn't hold true then goes on to show that it is as close an analogy as you need to understand the difference between a controlled reaction to the initial upset and the Co-Pilot Induced Ocillations, which resulted in the destruction of the aircraft. I am not a physicist, merely a pilot so the skidding car does it for me, thank you.

[Scurvy.D.Dog]

This fin exceeded regulatory requirements by very healthy margin … Airbus composite fins and rudders in general … or this particular (repaired) fin?
.
… in any event … are the ‘regulatory/certification requirements’ reasonable in that case??
.
… surely one must consider ‘possible’ rudder induced side load/s on the fin and attach points when paired with side load from inertial yaw forces + the H-M interface of 1.2 inches of pedal travel at 250kt??
.
… in turbulent wake, is 1.2 inches really giving pilots a fighting chance of achieving fine, targeted rudder effect ..which in turn might help avoid PIO’s??
.
.. common sense suggests the formular in a crude sense is:-
.
- provide enough surface and structural strength to enable management of required/possible flight envelope (then add margins)-
- limit control input parameters to protect the structure whilst providing necessary control authority to the pilots for 'unusual' encounters!
.
This should apply to all combinations of composite or alloy structures irrespective of control method (hydro-mechanical and/or fly-by-wire) Perhaps metal would bend before breaking, .. anyone aware of a ‘wake fin off’ accident with a wing slung alloy machine?? but that would be hardly helpful. .. what .. damaging a metal fin/rudder (whilst retaining it on the airframe) would give a crew less of more chance of a safe return that the whole thing breaking off?? … :hmm:
.
.. besides, if the initial aileron movement is indicative of the strength of the wake, the vortex may have clobbered the side of the fin/rudder in any number of directions over the elapsed time of the upset encounter ... is it therefore reasonable to expect pilots to provide a physical foot input of 'less' than 1.2inches in either direction whilst counteracting what they may well feel as substancial yawing (perhaps in more than one direction in quick sucession) effects!?
.
.. it is possible that if the aircraft encountered the wake climbing from beneth, the fin would be affected first and from one side (as a result of the rotational vortex stream), then if the aircraft was climbing at a greater rate than the aircraft ahead causing the wake, it would not take long for the fin to receive reverse side force from the upper area of the rotational horizontal wake vortex!
.
.. either way (weakened or not) .. and irrespective of the training and informed best intentions of pilots .. the question remains in my mind..
.
.. could any A300-600 airframe/pilot/turbulence combination result in a similar outcome ..???
.
… 1.2inches …. couple of rudder reversals at slow-ish' speed?? :ooh:
.
… hands up how many folks at the pointy end of these things tend to want to keep their feet up on the glare shield??? :oh:

[Mad (Flt) Scientist]

… Airbus composite fins and rudders in general … or this particular (repaired) fin?

This specific fin did not fail until in excess of twice design load, a margin of 33% over the requirement. So even if the repair did weaken the fin, it was still much stronger than it had to be. Which is precisely the basis on which ANY aircraft repair - whether in build or in service - is assessed - "Is it still strong enough to do what's required?"

… in any event … are the ‘regulatory/certification requirements’ reasonable in that case??

The only means whereby the regulations could be changed to directly address this accident would be to require active envelope protection for all airliners. On a conventional aircraft, where the pilot is the "Flight Control Computer", we rely on his training and airmanship to prevent inputs which risk the airframe structure. The design load manoeuvres required for certification are an ARBITRARY set of cases which have, in practice, proven adequate to provide sufficient structural margin for operations. Since there has been, basically, one event of this type, in who-knows-how-many billion flight hours, it would appear that the regulations are appropriate (the intent of the regulations is not to eliminate risk - that's impossible - but to reduce it to a level consistent with what's perceived as "safe")

surely one must consider ‘possible’ rudder induced side load/s on the fin and attach points when paired with side load from inertial yaw forces + the H-M interface of 1.2 inches of pedal travel at 250kt??

How many such inputs, and at what frequency? Make enough full rudder inputs at close to an aircraft response mode frequency and you WILL break any aircraft of conventional design.


.. common sense suggests the formular in a crude sense is:-
.
- provide enough surface and structural strength to enable management of required/possible flight envelope (then add margins)-
- limit control input parameters to protect the structure whilst providing necessary control authority to the pilots for 'unusual' encounters!

This is exactly what the A300 has: structure that didn't fail until it exceeded the regs by 33% (there's your margin), an RTL to protect the structure from excessive inputs AND enough rudder to meet the various regs for trim requirements.

The simple fact is that the only way to restrict control authority such that no-one can break their aircraft, whatever they do, is to either detach the pilot entirely from the controls, or to so limit authority as to make the aircraft almost unmanoeuvrable. Or make the structural design requirements so stringent it's too heavy to take off.

[Scurvy.D.Dog]

This specific fin did not fail until in excess of twice design load, a margin of 33% over the requirement. … design load … do you think the design load is right then?
.
.. 1.2inches of pedal a couple of times in wake and it failed! the intent of the regulations is not to eliminate risk - that's impossible - but to reduce it to a level consistent with what's perceived as "safe") … 1.2inches … full deflection .. wake reversals … 250kts … and it failed unsafe! How many such inputs, and at what frequency? Make enough full rudder inputs at close to an aircraft response mode frequency and you WILL break any aircraft of conventional design. .. such inputs as 1.2inches or less and a small number of reversal cycles?
.
.. that does not amount to full pedal left and right continuously in other types does it? This is exactly what the A300 has: structure that didn't fail until it exceeded the regs by 33% (there's your margin), … AH.. the ‘reg’s’!:suspect: an RTL to protect the structure from excessive inputs .. sorry, I must have missed how that worked in this case? AND enough rudder to meet the various regs for trim requirements. … and one would assume asymmetric envelope?!
…. The amount of rudder and its resultant authority is not at issue …. It is the rudder attach, the fin and the fin attach structural resilience to a part of the flight envelope that would not be too difficult to reproduce! ...... that has my full attention! The simple fact is that the only way to restrict control authority such that no-one can break their aircraft, whatever they do, ... thats is not what I am pondering ... again, is this such an unlikely or agressive reaction to a wake encounter?? is to either detach the pilot entirely from the controls, or to so limit authority as to make the aircraft almost unmanoeuvrable. Or make the structural design requirements so stringent it's too heavy to take off. … let’s not be silly! :hmm:

[Mad (Flt) Scientist]

… design load … do you think the design load is right then?
Yes, obviously I do, on the basis that inflight structural failure as a result of pilot inputs is Extremely Improbable. The regulations for this aspect of the design are "as safe" as any other regulation. Absolute safety is NOT the goal.

The 1.2 inches is actually irrelevant, since no-one's flying by pedal deflection. Compare force levels if you like, but pedal travel is pretty much secondary. And, yes, the A300 pedal force to rudder deflection gradient is pretty low, but it's by no means the only type with that characteristic. I suspect that +/-45lbf inputs would cause problems on any type with sufficient reversals.

The regulations are all we have to work with; no-one's going to start designing to arbitrarily higher targets, and in any case the regs ARE good enough in this case.

The RTL would have worked against the design case conditions - and who knows how large an input might have been applied if no RTL had been here in this case? It did what it could, and what it was designed to do; but it couldn't do enough to save the structure.

I'm not being 'silly', I'm pointing out that the practicality of aircraft design is that we accept risk every single flight, due to myriad causes. We simply cannot make the sturcture proof against all possible loading; we can't provide redundancy against every failure scenario. All we can do is achieve acceptable risk - currently about one hull loss per ten million FH - and accept that, sadly, one is greater than zero.

[barit1]

… anyone aware of a ‘wake fin off’ accident with a wing slung alloy machine?? ...

There are photos around of a SAC B-52 (early model) with most of the fin & rudder gone - she landed safely at a N. Michigan AFB (Kincheloe?) around 1960. I don't recall it being wake induced, though.

[DozyWannabe]

If Airbus is that confident of its engineering, why did it not arrange for such a test?
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.
… Airbus composite fins and rudders in general … or this particular (repaired) fin?
If anything, the only thing that the repair may have changed in this incident is the point at which the vertical stabiliser failed, in this case the rear rather than the front (where the repair was made) - Given the little I know about air resistance and centripetal force, I'd say it would probably have failed where it did regardless of the repair.
what .. damaging a metal fin/rudder (whilst retaining it on the airframe) would give a crew less of more chance of a safe return that the whole thing breaking off?? … :hmm:
Depends entirely on the failure mode. I believe that it would have made little difference what the rudder was made of if the design was the same, and a similar design has been good enough for the 767 and 777.
I don't think the B52 incident is a fair comparison as the failed vertical stabiliser lay flat over the horizontal and was of a different (split-rudder) design.

Finally, I'd like to repeat the point made in the link I posted, which is it is a crying shame that the incident has caused more response in terms of territorial disputes (pilots/airline vs. manufacturer, US vs. Europe) than it has in terms of co-operation to reduce or eliminate the chance of a similar failure occurring again.

Other aircraft made on both sides of the Atlantic (and Channel for that matter - Concorde was susceptible to partial vertical stab failure, and the vertical stab was built by BAC) have required special handling due to a design feature (the 737 required a faster approach speed while the ECU installed was of original design, for example), and other aircraft have been designed to reduce operating costs by reducing weight. The A320 which offended a certain breed of pilot for potentially endangering their job has no fewer guys in the sharp end than the 737, 757, 767 and 744 - and none of its envelope protection, which supposedly 'wrote the pilot out of the cockpit' prevents evasive maneuvres in an emergency.

In short, blowing hot air based on supposition and pride makes none of us safer and can in fact make things more dangerous, and if proof of that is needed, all we need do is think of the late Captain Stanley Key.

[Clandestino]

I'd like to ask future contributors to this thread to read NTSB report before contributing, thank you. It might help with improving signal-to-noise ratio.

If you're just reading this thread and wondering WTH was all rant in previous posts about, let me clear some misconceptions: AA587's fin wasn't ripped off by wake turbulence, it didn't fail because it was too weak and it wasn't rudder input alone that tore it either. It failed because of overload which was caused by massive sideslip and rudder deflection. Sideslip was created by rapidly alternating rudder movements. Examination of wreckage, FDR data, witnesses and airplane characteristics lead NTSB to conclusion that rudder input was commanded by PF, and not a result of control circuit failure.

Fact that American Airlines' Advanced Manuevering Programme was given FlightSafety award five days before the accident is quite ironic. Couple of posters are correct in noting that it never advocated alternating rudder inputs and always taught that rudder inputs should be smooth and coordinated but here's wher the problem lies. AAAMP's notion that rudder should be, under some circumstances, be used as primary flight control caused mr. Boeing and mr. Airbus to go apoplectic as this was one use of the rudder they never envisaged on airplanes they've made.

On a personal note I'd like to give you a qoute very fitting for this sad case:
Whenever we talk about a pilot who has been killed in a flying accident, we should all keep one thing in mind. He called upon the sum of all his knowledge and made a judgment. He believed in it so strongly that he knowingly bet his life on it. That his judgment was faulty is a tragedy, not stupidity. Every instructor, supervisor, and contemporary who ever spoke to him had an opportunity to influence his judgment, so a little bit of all of us goes with every pilot we lose.
This is from http://www.skygod.com/quotes/safety.html Don't be put off by a cheesy URL, the site is a real gem.

[Slats One]

Clandestino and the Scientist make good points. I quite agree that the fin in question was put beyond its design limits - and that it was stressed beyond its required limits. Indeed, its probable that any tail would have failed in such loads. (remember the Mt Fuji BOAC Boeing 707 side wind rotor fin failure?) .

In my posts all I wanted to do was raise the issue of what made it fail - in the light of subsequent events after AA587 - as opposed to events and knowledge at that time. This is a separate issue to what occurred and the limits applicable and performed to in structural terms.

[GlueBall]

Upon viewing the NTSB accident simulation video, it is obvious that the F/O had made overly aggressive and rapid aileron and rudder control inputs; ...a demonstration reminescent of a kid at play at a video arcade game.
"...[NTSB] Pilot Interviews Regarding the First Officer: An American Airlines captain who flew several times with the first officer on the 727 (when they were a junior captain and junior first officer, espectively) told Safety Board investigators that, during one flight sometime in 1997, the first officer had been “very aggressive” on the rudder pedals after a wake turbulence encounter. Specifically, the captain indicated that, when the airplane was at an altitude of between 1,000 and 1,500 feet, the first officer “stroked the rudder pedals 1-2-3, about that fast.” The captain thought that the airplane had lost an engine and was thus focused on the engine instruments. The captain stated that he then asked the first officer what he was doing and that the first officer replied that he was “leveling the wings due to wake turbulence.” The captain, who had his feet on the rudder pedals, thought that the first officer had pushed the rudder to its full stops.
The captain did not recall what type of airplane the 727 was following. He thought that the wake turbulence encounter required only aileron inputs to level the wings but did not think that the first officer had made any such inputs during the encounter. The captain recalled being startled by the first officer’s rudder inputs and indicated that they did not level the wings but created left and right yawing moments and heavy side loads on the
airplane. He further indicated that the first officer did not need to be so aggressive because the 727 was “a very stable airplane.”
According to the captain, he and the first officer discussed this event later in the flight. The captain pointed out to the first officer that his use of the rudder pedals was “quite aggressive,” but the first officer insisted that the American Airlines Advanced Aircraft Maneuvering Program (AAMP) directed him to use the rudder pedals in that manner. The captain disagreed with the first officer and told him that the AAMP directed that the rudder was to be used at lower airspeeds. The captain told the first officer to review the AAMP when he returned home and to be less aggressive on the rudder pedals when they flew together.
American Airlines records indicated that the flight occurred during a 3-day trip sequence from August 31 to September 2, 1997.
...on a subsequent flight, the first officer modified his wake turbulence maneuver; specifically, the first officer used the rudder during the encounter but did not push the rudder to its full stop. The captain added that the first officer was still “very quick” on the rudder. The captain stated that he did not document or report this event at the time that it occurred. The captain further stated that he remembered the event with such clarity because he had never seen any pilot other than the first officer perform this maneuver.
The flight engineer who flew with the captain and the first officer during the 1997 trip sequence recalled that the captain and the first officer had a discussion regarding piloting skills but added that he was not part of that conversation. The flight engineer indicated that he did not recall anything remarkable (such as a yawing event associated with wake turbulence) that would have provoked the discussion. The flight engineer also indicated that the first officer did not discuss the incident with him but that the captain
made a “passing comment” to him about the incident after the flight.
The flight engineer did remember a different event involving the first officer that he thought also occurred sometime in 1997. Specifically, the flight engineer and the first officer (the flying pilot) were on final approach (about 7miles from the runway) in instrument meteorological conditions to LaGuardia International Airport, New York, when a Boeing 737 ahead of their 727 performed a go-around. The 727 encountered the wake from the 737. The flight engineer thought that the airplane rolled as a result of the wake encounter but that the bank angle did not exceed 30º. The flight engineer stated that the first officer made a “fast” decision to go around because of the wake. The first officer called for maximum power without “discussion or hesitation.” The flight engineer explained that the airplane’s tail went down as the nose of the airplane pitched up. The flight engineer stated that the go-around felt “weird” but that the first officer “flew the airplane to do what was necessary to keep the airplane under control.” The flight engineer
also stated that the event happened when the airplane was at an altitude of between 3,000 and 5,000 feet above ground level (agl) and that the airplane was not in immediate danger of ground contact. In addition, the flight engineer stated that the event was one of the more memorable ones of his career. The captain indicated that the first officer’s aggressive response to wake turbulence was out of character. Specifically, the captain described the first officer’s overall flying skills as “excellent” and did not recall aggressive movements or abnormal rudder inputs during other trips with him..."

[AirRabbit]

There are photos around of a SAC B-52 (early model) with most of the fin & rudder gone - she landed safely at a N. Michigan AFB (Kincheloe?) around 1960. I don't recall it being wake induced, though.
Here's a link:
http://www.barksdale.af.mil/news/story.asp?id=123024862

[AirRabbit]

I'd like to ask future contributors to this thread to read NTSB report before contributing, thank you. It might help with improving signal-to-noise ratio.
If you're just reading this thread and wondering WTH was all rant in previous posts about, let me clear some misconceptions: AA587's fin wasn't ripped off by wake turbulence, it didn't fail because it was too weak and it wasn't rudder input alone that tore it either. It failed because of overload which was caused by massive sideslip and rudder deflection. Sideslip was created by rapidly alternating rudder movements. Examination of wreckage, FDR data, witnesses and airplane characteristics lead NTSB to conclusion that rudder input was commanded by PF, and not a result of control circuit failure.

Finally! A voice of reasoned professionalism. Thank you, sir!

[Scurvy.D.Dog]

.. have read the report!
.
.. a couple of quotes from your linkTake nothing for granted; do not jump to conclusions; follow every possible clue to the extent of usefulness . . . . Apply the principle that there is no limit to the amount of effort justified to prevent the recurrence of one aircraft accident or the loss of one life.
.
— Accident Investigation Manual of the U.S. Air Force. .. thus my questions above!I am a history major. I believe that the past is prologue. The archives bear that out. Most major aircraft accidents are not acts of God. In our recommendations we try to take what we have learned and correct situations so it shouldn't happen again.
.
— James Hall, NTSB, 1996. .. so what is happening to prevent a reoccurrence .... training pilots not to use rudder to correct perceived yaw/roll in wake conditions??
.
.. aircraft control systems/sensitivity and structure are all A OK then I assume?! :confused:
.
.. anyhow, over to the experts ... :p
.
... I hope 2007 is a safe and happy year for us all! :ok:
.
Cheers
.
Scurv

[bomarc]

after reading everything about this sad accident I call upon the NTSB to properly admonish the FAA and demand changes to enhance safety.

The FAA certified the aircraft and its manual(POH)

The FAA certified the airline operating the plane

The FAA certified the airline's training program

The FAA certified the pilot. And along the pilot's career had the opportunity to test the pilot's knowledge of rudder inputs and their effects many times...written and oral exams for the private, commercial, instrument rating, multi engine rating , airline transport pilot certificate and perhaps others including type rating.


regarding the SAC B52 incident, I think there was one another one due toloss of vertical fin leading to a crash somewhere near Cumberland Maryland about 45 years ago or so. I'll bet the pilot didn't rock the rudder!

[bubbers44]

after reading everything about this sad accident I call upon the NTSB to properly admonish the FAA and demand changes to enhance safety.
The FAA certified the aircraft and its manual(POH)
The FAA certified the airline operating the plane
The FAA certified the airline's training program
The FAA certified the pilot. And along the pilot's career had the opportunity to test the pilot's knowledge of rudder inputs and their effects many times...written and oral exams for the private, commercial, instrument rating, multi engine rating , airline transport pilot certificate and perhaps others including type rating.
regarding the SAC B52 incident, I think there was one another one due toloss of vertical fin leading to a crash somewhere near Cumberland Maryland about 45 years ago or so. I'll bet the pilot didn't rock the rudder!

Ok, now that we have our aviation safety problem solved guess we will be traveling by trains and automobiles for quite some time.

[Mad (Flt) Scientist]

so what is happening to prevent a reoccurrence .... training pilots not to use rudder to correct perceived yaw/roll in wake conditions??
.
.. aircraft control systems/sensitivity and structure are all A OK then I assume?! :confused:

Well, amongst other things that have happened (references are to the NTSB recommendations in the accident report)...

All the OEMs have put some kind of warning about excessive control use in their flight manuals, I believe.(A-04-59)
Pilots are now, I hope, much more aware that control inputs below VA are not necessarily within the design envelope. (A-04-60)
The AA training programme was, I believe, reviewed.(A-04-61/62)
All the major manufacturers were asked (required?) to check their structure against manoeuvres more like the AA587 one (rudder doublets)
NTSB (or FAA? - I forget) has been requesting info from all the OEMs regarding rudder system characteristics.(Those last two for A-04-56 and -57, I believe)

So it is conceivable that a change to the regulations will eventually be forthcoming, though I expect it will be concerned with issues of control sensitivity, not the structural design criteria.

[misd-agin]

So it is conceivable that a change to the regulations will eventually be forthcoming, though I expect it will be concerned with issues of control sensitivity, not the structural design criteria.

Control sensitivity is at the heart of this incident. I'd hope the regulations require a design similar to what the newer (757/767/777) Boeing's have. From a human factors POV using that rudder design makes sense. That, coupled with a lower sensitivity rate, should be the 'Gold Standard' of a/c design.

[AirRabbit]

after reading everything about this sad accident I call upon the NTSB to properly admonish the FAA and demand changes to enhance safety.
The FAA certified the aircraft and its manual(POH)
The FAA certified the airline operating the plane
The FAA certified the airline's training program
The FAA certified the pilot. And along the pilot's career had the opportunity to test the pilot's knowledge of rudder inputs and their effects many times...written and oral exams for the private, commercial, instrument rating, multi engine rating , airline transport pilot certificate and perhaps others including type rating.

Your comments about what the FAA certified are mostly correct (they didn’t “certify” the training program, they only “approved” it, and the Airplane Flight Manual was also “approved” – not the Pilot’s Operating Handbook) but I’m not being critical. My questions, however, do have critical components.

For what is it you think the NTSB should admonish the FAA?

Why is it you believe that the NTSB has not admonished the FAA?

IF the aircraft met the certification requirements, on what basis would you have had the FAA deny the issuance of the airworthiness certificate?

IF the airline said they would operate the airplane the way in which it was certificated, on what basis would you have had the FAA deny American the authorization to operate that aircraft?

IF the airline structured a training program that met all the regulatory requirements AND incorporated all of the required tasks AND those tasks that may have been particular to that specific aircraft, on what basis would you have had the FAA deny the approval of the training program?

What specific task or airborne maneuver would you have the FAA add to its list of tasks/maneuvers that would, in your opinion, insure that the pilot would not misapply any of the training or aircraft certification limits?

Where and how frequently should the FAA add the task(s)/maneuver(s) you suggest to their testing requirements?

[bomarc]

l think that the certification, approval and measuring of pilots should all be redone to insure safety.

you see, safety was lost, along with the passengers and crew...if everything met FAA requirements and safety was lost, then requirments must be changed.

I would start with the aircraft...full control throw may be used by the pilot at all speeds below and specifiy a speed. OTHERWISE a placcard must be installed to warn the pilot that full control throw may cause loss of the aircraft.

[barit1]

Alternatively:
Pilot training should include Pilot-In-Loop (or whatever the fad term is) oscillation awareness training, how to recognize it, and how to break the cycle before the airplane breaks. This can likely be implemented much faster than changed design requirements.
I'm not dissing any design or cert changes, just acknowledging the lead times therein.

deja vu: doesn't this AA587 episode read rather like Neville Shute's "No Highway"?

[AirRabbit]

l think that the certification, approval and measuring of pilots should all be redone to insure safety.
Would that be all pilots, pilots flying for American, pilots flying transport category airplanes, pilots flying A-300s, pilots flying Airbus equipment, or pilots being paid to fly, … of course, this list could go on … but, I think you get the idea.
you see, safety was lost, along with the passengers and crew...if everything met FAA requirements and safety was lost, then requirments must be changed.
Do you have a specific requirement that should be changed? Or does that mean all requirements should just change? Is there a suggested amount of change you had in mind? And, should all the rules and requirements be changed every time there is an accident … and only half of those rules and requirements each time there is an incident? Just wondering?
I would start with the aircraft...full control throw may be used by the pilot at all speeds below and specifiy a speed. OTHERWISE a placcard must be installed to warn the pilot that full control throw may cause loss of the aircraft.
Uh ... which do you mean? "Movement of the control to the stops." OR "Movement of the control to the stops, and immediately reverse to the other stop, and immediately reverse to the other stop, and immediately reverse to the other stop, and immediately reverse to the other stop, and immediately reverse ... and so on until structural failure occurs."
If it's the first one - no problem. If it's the second one, I DO NOT volunteer to gather the flight test data!

[bomarc]

barit 1

regarding, "NO HIGHWAY" by Shute, yes, in some ways it does remind me of the book:

step 1: blame the pilot

step 2: have boffin working on new theories of aircraft construction , use concept of general research and not specific aircraft research to add tension.

step 3: have a bunch of other pilots speak out saying that a pilot couldn't do this to a a "good" plane.

step 4: have manufacturer demand that plane not be held to blame


step 5: find out that plane was POS clearing pilot.


hmmmm, lessons learned in advance for metal fatigue and something akin to composite problems.

Solution: in the book, fly less than 1500 hours on airframe. in the crash under discussion, just tell the pilots not to do something with the rudder.



air rabbit:

simply put, if all pilots didn't know that described rudder movements would cause plane to break apart in flight, then all PILOTS must be instructed and tested. At airlines, easily done in sims. A GA pilot could be given this info during their BFR.

Without creating a 50 page document on exactly what to do, isn't it better that we all just agree that the proper thing needs to be done? that plane builders build something more robust? that pilots be a little more careful? and that we must all still wonder a bit...maybe, just maybe something failed causing the copilot to wiggle the rudder in such a fashion?

[fyrefli]

Without creating a 50 page document on exactly what to do, isn't it better that we all just agree that the proper thing needs to be done?

How on earth (or a little above it!) can one do "the proper thing" without very detailed agreement on what "the proper thing" is? Aviation safety is not going to be improved one iota by adopting the headless chicken, reactionary mentality increasingly beloved of incompetent, Peter Principle, middle management, grandstanding politicians and knee-jerk lawmakers.

[DozyWannabe]

regarding, "NO HIGHWAY" by Shute, yes, in some ways it does remind me of the book:
step 1: blame the pilot
...
step 4: have manufacturer demand that plane not be held to blame
step 5: find out that plane was POS clearing pilot.
hmmmm, lessons learned in advance for metal fatigue and something akin to composite problems.
Solution: in the book, fly less than 1500 hours on airframe. in the crash under discussion, just tell the pilots not to do something with the rudder.
I know I'm not Barit1, but I think it's worth pointing out that 'No Highway' was written in 1948, and very much described procedures as they were at the time. The AAIB and NTSB didn't even exist then, and the RAE was the domain of brilliant theoreticians with slide rules and theories. It took the Comet tragedies to highlight the importance of forensic investigation in tandem with the theories and predictions of the 'boffins'.

It's also worth noting that the fictional Dr. Honey's theories in the book, while making for a good story and necessary cautionary tale did not apply in the real world and that the greatest fatigue threat came from pressure cycles, not aircraft velocity.
Without creating a 50 page document on exactly what to do, isn't it better that we all just agree that the proper thing needs to be done? that plane builders build something more robust? that pilots be a little more careful? and that we must all still wonder a bit...maybe, just maybe something failed causing the copilot to wiggle the rudder in such a fashion?
Good points, but the fact remains that the A300 is perfectly robust. The reason that a DC9 is more capable of handling rudder oscillations is a function of the rear-engined design - i.e. you need less rudder travel and a smaller surface area to make a difference than in an aircraft with wing-mounted engines, which has been the prevalent design in almost all large airliners since the 1960s, including those from Douglas and Boeing.

To say that the pilot tended to use more rudder than average and showed a reluctance to engage wake turbulence is not disparaging the man or his skills, he did as he was trained, and as he felt necessary. I don't think any pilot enjoys a wake encounter at slow speed because it has after all caused fatal accidents in the past.

I'll concede that it is difficult to prove conclusively in which order the events happened regarding the rudder pedal reversals and the loss of the stabiliser, but the fact that it wasn't until after the inputs were made that the FDR data for the rudder became unuseable suggests that the inputs were made first.

By saying that, this was a classic 'holes in the cheese' incident. No one factor can be singled out for blame because both the aircraft and the pilot did what their design and training respectively said they would do.

[pontifex]

I have just got back after some time away to find this thread running AGAIN!
I well remember John Farley's post very soon after the event when he drew attention to the difference between Static and Dynamic sideslip. It was reasoned and clearly authoritative but it seems to have been lost in the noise. I was taught on the test pilot course that sideslip is the most critical limit on any aircraft of any sort and it is only too easy to exceed it in some circumstances. Any aircraft, to get certificated, must demonstrate that it cannot get anywhere near its static limit - ever. But, what about the dynamic situation? You have a large chap on a swing and he wants you to give him a push: you can move him a couple of feet or so on the first go. If you give him another push when he is coming back he will more or less stop. However, if you wait until he has just started to move again in the original direction, and give another shove, the amount he moves (the amplitude) will increase. As we all know eventually he will eventually shout stop or fall off having exceeded the swing's limits. Sideslip is like that with the rudder movement being the push; it doesn't even have to be full deflection movements, just in the right direction at the right time. This is what happened to the Airbus. Given the same mishandling the fin would have fallen off any airliner no matter who made it. Why doesn't it happen in Pitch? - too uncomfortable for any one to get there inadvertently, but it would certainly be possible to pull the wings off if you tried.

There have been too many special interests at work in this unfortunate incident with the lawyers hovering like vultures in the back ground. Static and dynamic sidslips are differebt breeds of the same animal; one can be quantified and measures taken to limit it, the other one cannot be quantified and, thus, cannot be protected against. Having said that I recon it is not beyond some clever software engineer to devise a means of doing so on a fully FBW aircraft.

[arcniz]

There have been too many special interests at work in this unfortunate incident with the lawyers hovering like vultures in the back ground. Static and dynamic sidslips are differebt breeds of the same animal; one can be quantified and measures taken to limit it, the other one cannot be quantified and, thus, cannot be protected against. Having said that I recon it is not beyond some clever software engineer to devise a means of doing so on a fully FBW aircraft.
With a couple or three accelerometers and a teensy bit of power, a sensor unit the size of a cigarette package in the tail area could provide all the measuring needed, and a similar-size box up forward with access to an airspeed data signal would be able to provide numeric data for the logs and an actuation signal for panel or efis display advising caution or emergency status re dynamic sideslip. Log data from same would be useful for assessing cumulative airframe & tail stress history. Cheap (in aviation terms), easy enough to make and retrofit. No FBW and no rocket science required. How many would you like?

[bomarc]

maybe the tail mounted engine planes are easier to make safer in this situation...smaller vertical stab, smaller rudder...granted a little less efficient.

and as to the concept of a detailed analysis of what is wrong and how to fix it...what do we do in the meantime?
--
I think Dr. Honey's work ( no highway) was on the amount of vibration prior to failure and it was affected by the temperature (balloon shed vs inflight in the tropics).

I think detailed analysis and a full understanding is vital...but again, we have seen one disaster, and seen a similiar problem, if not identical on a similiar type of plane (transat, cuba).

time to rethink pilot training, aircraft certification, structure of composites and the like.

remember folks, its been 5plus years. is this just waiting to happen again? just waiting for the right amount of rudder, wake, and X?

[AirRabbit]

Static and dynamic sidslips are different breeds of the same animal; one can be quantified and measures taken to limit it, the other one cannot be quantified and, thus, cannot be protected against. Having said that I recon it is not beyond some clever software engineer to devise a means of doing so on a fully FBW aircraft.

With a couple or three accelerometers and a teensy bit of power, a sensor unit the size of a cigarette package in the tail area could provide all the measuring needed, and a similar-size box up forward with access to an airspeed data signal would be able to provide numeric data for the logs and an actuation signal for panel or EFIS display advising caution or emergency status re dynamic sideslip. Log data from same would be useful for assessing cumulative airframe & tail stress history. Cheap (in aviation terms), easy enough to make and retrofit. No FBW and no rocket science required. How many would you like?
If what you’re describing is something akin to FDR information – you bet! However, and again, without meaning to sound overly critical, I’m not sure that putting additional displays “…advising caution or emergency status regarding dynamic sideslip…” is something that would be valuable to the crew. You can see, from the animation provided, it was a maximum of 9 seconds between the first indication of the last turbulence encounter to the point where something major occurred – causing loss of some or all of the data feed – like the loss of the vertical tail. Nine seconds! Even if the data sensors read, computed, and displayed whatever data might be appropriate in less than a second, such a system would still require some data-trace history on which to base its computations (and the technical folks would have to tell us what that time requirement would be), the crew would have to notice, read, interpret, and respond (and respond correctly) to that notification in something considerably less than 8 seconds. Also, I would think there would have to be a pretty standard control application strategy developed (and likely practiced) that could be applied in such a circumstance or it is likely that the “interpret/respond” portion of that strategy would be significantly longer. And with any delay, the likelihood of experiencing a similar structural failure would go up at an alarmingly quick rate.

I recognize that the A-300 has a particularly different rudder and rudder pedal deflection relationship from other, large transport category airplanes. Is this what needs to be examined? I think that a simple reading of the aircraft certification requirements in a ground school class would be most enlightening as well. Also, examining aerodynamic controls during initial flight training and revisiting this area during recurrent flight training is important in all airplanes; and I keep coming back to the reason that a controllable rudder is on the airplane in the first place – that being to keep the airplane in a “coordinated” flight condition. Roll control spoilers have been around for a long time … perhaps to the extent that newer (read, “younger”) pilots have not had the opportunity to fly the airplanes they fly without that particular addition – which, as most of you know, handsomely reduces the necessity for pilot application of rudder to maintain that “coordinated” flight condition under most circumstances. When you get into a lateral/directional PIO – which isn’t taught in very many (if any) airline training programs – I believe the existence of roll control spoilers may well complicate the understanding of what is happening and what should be done to escape from that PIO. Knowing the problem and knowing what to do about either eliminating the problem or extracting oneself from having encountered the problem are not necessarily the same things.

[cornwallis]

Airbus has recently imposed on the A300-600 some large penalties on MTOW with crosswinds greater than 20kts.This has been imposed without any explanation.Perhaps it could have something to do with rudder effectiveness.

[hetfield]

Airbus has recently imposed on the A300-600 some large penalties on MTOW with crosswinds greater than 20kts.This has been imposed without any explanation.Perhaps it could have something to do with rudder effectiveness.

No, don't think so. Check your pm.

Kind regards

[Few Cloudy]

Hmm.

Some pretty outspoken claims above.

My question - which passenger jet aircraft will stand full rudder cycles at
a fast sequence without damage?

Any of you guys care to try it out?

I certainly wouldn't - even on my favourite DC-9 family with limiters.

That's a big barn door of a control up there. It is there to counter engine
failure side forces and needs a lot of respect. I don't even like to see fast rudder actuation on the ground during control checks. Easy does it.

FC.

[pontifex]

Few Cloudy. I couldn't agree more with your comments on rapid control movements - not a good idea unles you are looking to do flick manoeuvres during aerobatics. However, the most important point here is that the speed of the movements or their rapidity is nowhere near as important as their frequency in relation to the aircraft's natural yaw response. If they are in synchronisation, then there's trouble!

[pontifex]

Few Cloudy. I couldn't agree more with your comments on rapid control movements - not a good idea unles you are looking to do flick manoeuvres during aerobatics. However, the most important point here is that the speed of the movements or their rapidity is nowhere near as important as their frequency in relation to the aircraft's natural yaw response. If they are in synchronisation, then there's trouble!

[bomarc]

few cloudy

I think you make an important point. none of us as airline pilots would, in the course of smooth manual flight, "flick" the rudder around...or any controls really.

(recall how over controlling the 757 at KSEA was shown during a crosswind landing...see other thread(hairy xwind landing)...it didn't come apart.

the copilot in this crash probably wouldn't either, especially after the admonishment some years earlier while on the 727 (which did seem to survive the rudder movement).

all of this makes me think that there is more than meets the eye to the crash in question. that something happened in a different sequence than we are lead to believe.

I am sure that If I danced on the rudders at 200+knots I would make myself quite air sick. that should be a limiting factor in and of itself.

[AirRabbit]

few cloudy
I think you make an important point. none of us as airline pilots would, in the course of smooth manual flight, "flick" the rudder around...or any controls really.
(recall how over controlling the 757 at KSEA was shown during a crosswind landing...see other thread(hairy xwind landing)...it didn't come apart.
the copilot in this crash probably wouldn't either, especially after the admonishment some years earlier while on the 727 (which did seem to survive the rudder movement).
all of this makes me think that there is more than meets the eye to the crash in question. that something happened in a different sequence than we are lead to believe.
I am sure that If I danced on the rudders at 200+knots I would make myself quite air sick. that should be a limiting factor in and of itself.
With all due respect, sir, once again, please review the animation video taken from the FDR. Someone was "on" the rudder pedals! And whomever it was, certainly wasn't very timid with the application.

At the initiation of the control inputs, likely as a result of the second wing-tip vortex encounter, you can see a right rudder pedal deflection to the stop and a control wheel input of about 80 degrees to the right. Of course, with full right rudder and darn near full aileron to the right, the airplane begins a roll to the right (back toward wings level). However, when the airplane reaches about 20 degrees of left bank (at time marker 09:15:52) while rolling to the right you can see a simultaneous control wheel and rudder surface movement to the left. I don't know about you, but to me, that is an "Ouch" of the first order! The rudder surface actually looks to exceed the pedal limit (but I don’t know if this is an anomaly with the indicator or not) and the control wheel gets to darn near full control wheel displacement. This means at least 160 degrees of wheel change and probably something like 8 – 10 degrees of rudder surface change – all in 1 second, to the left as the airplane is rolling to the right. Another major "Ouch!" Again, with all this opposite control surface input, the roll to the right is almost stopped (at about 10 degrees of left bank).

To add to the excitement, the full left aileron position is not maintained, nor is the full left rudder pedal position. The wheel is brought back to something like 10 degrees to the right simultaneously with application of full right rudder pedal deflection in 1 second, ("Ouch!") probably reaching constant rate saturation again. While full right rudder is maintained, the control wheel is moved back to about 10 degrees left – again, in 1 second ("Ouch!"). This particular control wheel movement may not have reached the constant rate saturation level again – but it was probably darn close. As the rudder pedal deflection is maintained (very likely getting close to a stable sideslip), the control wheel is moved back to the right to just about full wheel travel and the rudder pedal exceeds the pedal limits – again taking a total of 1 second (again, "Ouch!"). Immediately, the rudder pedal is repositioned to full left deflection, and, in fact, goes well beyond the limits (again depending on the accuracy of the display), simultaneously the control wheel is deflected full left – again, in 1 second ("Ouch!"); time marker 09:15:56-57. As the control wheel is moved back to the right (to about 45 degrees), the rudder pedal deflection goes full right and the surface position presentation disappears (time marker 09:15:58), while the pedal position continues to show full right deflection. There is little doubt that this is where the data feed was stopped – probably because of the departure of the vertical stabilizer and rudder. The control wheel goes back to about neutral and back again to a right control wheel deflection of about 45 degrees.

By the time the rudder surface position display blanks out, there were 7 control wheel reversals and 5 rudder pedal reversals, all in about 7 seconds. Please note ... these were NOT surface position readings ... these were cockpit control positions - and this airplane does not have reversible controls. If these controls were moved, someONE in the cockpit moved them.

The B-757 KSEA crosswind landing attempt had no control inputs that approached the magnitude, frequency, or reversals as on this particular AA flight! Most approaches, even in nasty crosswinds, are not conducted with a clean wing and 250 Knots; but, still, I would think that if anyone DID make such an approach, and "danced" on the rudder along with making the associated lateral control inputs as happend with AA587, I'm not too sure that pilot wouldn't have had more than his hands full as well!

Assuming the rudder pedal movement wasn't the Captain, it would seem that the "admonishment" the F/O received some years earlier, didn't "take."

Of course, there ARE conspiracy theorists under almost every rock - with "theories" about every thing. Why should this accident be any different?

[bomarc]

dear air rabbit:

quite frankly, for the future of air safety, I do hope that the copilot is fully at fault...but I don't think that is really the case. In almost all wake turbulence encounters, climbing above the wake is almost always the best course of action.

if the copilot was dancing on the rudder pedals in an excessive fashion, why wouldn't the captain say, "I'VE GOT IT" and take over control? Why nothing like, "what the hell are you doing to the rudder? on the CVR...if this is on the CVR please let us all know.

Even your post indicates the possiblity of something wrong with the indicator as it seems that the rudder may have moved too

far <<The rudder surface actually looks to exceed the pedal limit (but I don’t know if this is an anomaly with the indicator or not) and the control wheel gets to darn near full control wheel displacement. >>


Conspiracy theories? sure, why not? the second shooter at dallas? roswell? and blame the pilot.


IN the USA, there are about 25 passenger Airbus 300 aircraft? Isn't that about right?

[Mac the Knife]

Forgive me for enquiring of the elite, but I'd like to ask...

"By the time the rudder surface position display blanks out, there were 7 control wheel reversals and 5 rudder pedal reversals, all in about 7 seconds."

This is a large aircraft, not an aerobatic biplane - surely it could hardly have even begun to respond to one control input before another was initiated (and so why the rapid reversal?)?

Just asking, if you don't mind.

[misd-agin]

Forgive me for enquiring of the elite, but I'd like to ask...

"By the time the rudder surface position display blanks out, there were 7 control wheel reversals and 5 rudder pedal reversals, all in about 7 seconds."

This is a large aircraft, not an aerobatic biplane - surely it could hardly have even begun to respond to one control input before another was initiated (and so why the rapid reversal?)?

Just asking, if you don't mind.

The A300 has the lightest control forces, and perhaps the quickest response(havn't timed them) of any large jet a/c I've flown or jumpseated in. Flown would be 5 large jets, j/s'd would add three additional types.

I've been with folks that have over controlled roll inputs. All the hydraulically powered jets with roll spoilers react very quickly. Review the NW 757 @ SEA video and watch how quickly the a/c responds once the roll spoilers extend to a signifcant angle.

[misd-agin]

IN the USA, there are about 25 passenger Airbus 300 aircraft? Isn't that about right?

34 in passenger service with more at the freight carriers.

[misd-agin]

few cloudy

I think you make an important point. none of us as airline pilots would, in the course of smooth manual flight, "flick" the rudder around...or any controls really.

(recall how over controlling the 757 at KSEA was shown during a crosswind landing...see other thread(hairy xwind landing)...it didn't come apart.

the copilot in this crash probably wouldn't either, especially after the admonishment some years earlier while on the 727 (which did seem to survive the rudder movement).

all of this makes me think that there is more than meets the eye to the crash in question. that something happened in a different sequence than we are lead to believe.

I am sure that If I danced on the rudders at 200+knots I would make myself quite air sick. that should be a limiting factor in and of itself.

On a scale of 1-100 abrupt rudder inputs at 160 kts is similar to taking off in gusty conditions. Call it a 10. 210 kts rudder inputs would be 20-30, and 250 kt rudder inputs are 100.

The magnitude of the lateral movement/load increases exponentially. So much so that the AA pilots union had expert testimony about the sensitivity being close to a POI response rate.

[AirRabbit]

Forgive me for enquiring of the elite, but I'd like to ask...
"By the time the rudder surface position display blanks out, there were 7 control wheel reversals and 5 rudder pedal reversals, all in about 7 seconds."
This is a large aircraft, not an aerobatic biplane - surely it could hardly have even begun to respond to one control input before another was initiated (and so why the rapid reversal?)?
Just asking, if you don't mind.
The A300 has the lightest control forces, and perhaps the quickest response(havn't timed them) of any large jet a/c I've flown or jumpseated in. Flown would be 5 large jets, j/s'd would add three additional types.
I've been with folks that have over controlled roll inputs. All the hydraulically powered jets with roll spoilers react very quickly. Review the NW 757 @ SEA video and watch how quickly the a/c responds once the roll spoilers extend to a signifcant angle.
On a scale of 1-100 abrupt rudder inputs at 160 kts is similar to taking off in gusty conditions. Call it a 10. 210 kts rudder inputs would be 20-30, and 250 kt rudder inputs are 100.
The magnitude of the lateral movement/load increases exponentially. So much so that the AA pilots union had expert testimony about the sensitivity being close to a POI response rate.
Hey Mac the Knife … I’m not sure about the “elite” remark, but … your question is an excellent one; “why the rapid reversal?” THAT is the $64 question! I think if you watch the animation of the FDR provided by the NTSB, you will see that the aircraft did begin to move in the direction mandated by the control inputs. It IS a large aircraft … and the momentum it would build up would be substantial … and to reverse that momentum would take A LOT of force. But, THAT is precisely the point. Of all the control reversals noted on the FDR in that 9 seconds, I believe only one was held long enough to potentially allow the aircraft to get close to stabilizing with THAT particular control input. In each of the other cases, the momentum was established … that is, the aircraft began movement in the commanded direction … and then, because of control reversal, that momentum was stopped and reversed … multiple times … in a VERY short period of time. As any structures expert will confirm, while rapid control movement will stress the structure, a significantly larger stress, by far, is generated from applying full control input opposite the movement of the structure.

I don’t know that we’ll ever know the “why” behind this particular accident. It would appear that the F/O was pre-disposed to the aggressive application of rudder, and that he was also very quick to apply what he thought was necessary control input to prevent what he thought was happening, or was about to happen, to his airplane. Again, the FDR traces of the cockpit controls (i.e. column, wheel, and pedal) indicate that those controls were displaced – and since they are not “back-driven,” someone in the cockpit had to displace them.

I hope that the readers here don’t think I’m saying that the complete responsibility of the accident is the fault of the F/O. However, he WAS “on” the controls … so he bears at least part of the responsibility. But, as I’ve said, I think he had significant “help” in getting to the scene of the accident. The control sensitivity of the airplane helped. (I’m not rated on the A-300 so I appreciate misd-agin’s comments about light control forces and quick responses.) The training to which he was exposed helped. The understanding of “design maneuvering” speed (or more likely, the “mis-understanding” of that term) helped. His own control application strategy helped. Not being able to recognize and escape from a “pilot induced oscillation” (PIO) also helped.

With these “helpful” pieces all fitting together, along with the comments offered by misd-agin regarding the exponential increase in structural “load” with airspeed increase, I think that the result of the sequence of these particular events is rather straight-forward. My hope is that pilots will take away from this event several important pieces of information … an understanding of the way aircraft are certificated; an understanding of what control inputs due to the airplane; an understanding of what a PIO really is, how to recognize one, and, most importantly, how to get OUT of one if one does develop.

Let me add one additional and very important point here. I think it important to say, and to say clearly, the development of a PIO is NOT necessarily an indication of poor piloting technique. It’s somewhat like a squad of soldiers marching across a bridge … such an event is ALWAYS done “out-of-cadence” as a precautionary measure to avoid setting up a resonant frequency vibration. A PIO is similar. A PIO is almost always initiated through some triggering event – that may, or may not, have a pilot input involved. But once the trigger has occurred, the pilot’s response is critical to either adding to or damping out that PIO. It’s hard to dampen out a PIO unless you know that you are in one, AND you know HOW to get out of one. Maybe these things will be included in future pilot training programs.

[Rainboe]

Bomarc

if the copilot was dancing on the rudder pedals in an excessive fashion, why wouldn't the captain say, "I'VE GOT IT" and take over control? Why nothing like, "what the hell are you doing to the rudder? on the CVR...if this is on the CVR please let us all know.
you are apparently convincing yourself, as many people do in many incidents, that 'there is more to this than meets the eye!'. That 'we are not being told the full story!'. The Captain was not flying, his feet would not have been on the pedals. When the vortex encounter hit, it was obviously very powerful. He would have been more concerned about watching the situation. If he felt the copilot was handling it and responding correctly, I believe he would not have been looking down at the pedals (more important to monitor what was happening), or placing his own feet on them as this would interfere with the copilot's handling. Why should he take control immediately? Seeing the aileron control moved in front of his nose, he would be confident the copilot was responding. I am sure he was probably unaware of large rudder inputs in the buffeting, turbulence and strong roll being experienced. So please don't lead yourself up a wrong track!

[Mac the Knife]

AirRabbit, thank you for your courteous reply. It helps a bit, but I still don't quite see what he was trying to achieve by this.

I don't fly (in my next life!), but I do sail small boats, so for me it's as if he'd put the tiller hard over and then, just as the bows started to swing, slammed the tiller hard over to the other extreme. And then repeated this 4 more times.

This won't get you anywhere in a small boat and I can't imagine a situation when one might do this, even in a blow and a running sea. I know aircraft are not the same as small boats but it still sounds rather odd.

I'm sorry if it's a silly analogy but I'm trying to understand.

PS: On reflection, you might well break the rudder off in a dinghy if you tried this, so what happened is not that surprising. But why do it?

[bomarc]

dear rainboe:

I've been in the left and right seat of jet transports...and I have never been out of touch with what the other pilot was doing with all the flight controls...

I suppose we shall just disagree courteously on this concept.

---

I do ask the following question for all the pilots on the forum:

Given the following:

pay the same
schedule and destinations the same

equality of good looking flight attendents the same

all the same on everything except the plane:


would the airbus 300 series be your first choice in planes to fly? you may choose from any plane currently flying, comparing it to the above plane?

hypothetical of course.

[bubbers44]

I was scratching my head on the captain having his feet on the floor too. I thought all pilots monitored all flight controls when the other pilot was flying especially during critical phases of flight or when something unusual was happening.

I have talked to the pilot flying the A300 trying to land at MIA when he got continuing uncommanded rudder inputs forcing him to go around. He questioned whether they would be able to control it enough to get on the runway at all. No, I wouldn't fly an airbus 300 if I had any other choices no matter how good looking the FA's were or how well it paid.

[Desert Dingo]

No, I wouldn't fly an airbus 300 if I had any other choicesYeah. All airbusses are crap, aren't they?
The newer ones are fly-by-wire, and the software won't allow pilot input to stall or over stress the airframe.
The older ones, however, will allow a ham-fisted (footed?) pilot to over stress the airframe.
Just like the Boeings that real men fly.
Errr... :confused:

[Rainboe]

Well you two (bomarc and blubbers) surprise me. In the normal course of events, a Captain would be aware of what the Pilot Flying the aircraft (in this case the co-pilot) was doing on the controls, but throw in a violent wake encounter and I think he would be forgiven for just concentrating on what was going on rather than monitoring the controls, as evidenced by his lack of comment or overcontrol on the rudders.
For myself, I would be just as happy to fly the A300 as I am to fly the 737 now. Like almost all pilots, I am happy with its certification just as the A300 deserves its certification. You can overcontrol any aeroplane in all phases of flight. Many of us have always been aware of the dangers of overcontrol- I do not understand why so many pilots now seem to find it a shock that it can occur. I started 35 years ago on the VC10 and recalled being hit with a rolled up newspaper for being too 'expressive' on the rudder during dedicated training flights.

[AirRabbit]

AirRabbit, thank you for your courteous reply. It helps a bit, but I still don't quite see what he was trying to achieve by this.
I don't fly (in my next life!), but I do sail small boats, so for me it's as if he'd put the tiller hard over and then, just as the bows started to swing, slammed the tiller hard over to the other extreme. And then repeated this 4 more times.
This won't get you anywhere in a small boat and I can't imagine a situation when one might do this, even in a blow and a running sea. I know aircraft are not the same as small boats but it still sounds rather odd.
I'm sorry if it's a silly analogy but I'm trying to understand.
PS: On reflection, you might well break the rudder off in a dinghy if you tried this, so what happened is not that surprising. But why do it?
Well, I don’t think it’s a silly analogy, and, as I said, the “why” is the big question here. The “what” of this accident is not terribly difficult to understand – even though some here would want to argue with the findings of the NTSB. It appears that, in addition to improperly using the rudder to prevent a roll from occurring, this pilot actually developed an oscillation similar to what is called a “Dutch roll” – where the yaw-roll coupling is excited. He then managed to exacerbate this oscillation and continued to apply, and then reverse apply, maximum (or nearly maximum) roll and yaw control inputs until the tail structure failed.

You are not alone in trying, but failing, to know “why” this pilot did what he did. Given that this pilot was certainly not a novice pilot, I would presume that the “why” included the fact that he thought he was doing the right thing to prevent what he thought was happening, or was about to happen, to his aircraft. He had just encountered wing-tip vortices from the preceding aircraft (the JAL B-747), and I presume he was responding to a second encounter. Further, it appears that he thought the proper control application strategy included the aggressive use of rudder application. Normally, a pilot is trained to use the rudder to keep the airplane in a “coordinated” flight condition. The instrument used to verify the need for such control, as well as indicating the direction and the magnitude of that control input, is the inclinometer, commonly called the “slip/skid” ball. The idea is to “keep the ball in the center,” and by doing so, keep the airplane in “coordinated” flight; that is, not skidding and not slipping. I’m not familiar with the A-300 so I don’t know if there is an electronic version of the inclinometer that was recorded as part of the FDR, or if there is only a simple, mechanical inclinometer available for pilot reference. I only know that the animation included vertical and lateral acceleration indications, which are not necessarily the same.

There was some testimony/evidence that was presented during the investigation of this accident that indicated this pilot may have been trained to use the rudder during other situations – like the recovery from “other than normal” attitudes. However, the evidence and testimony also shows that this training always included references to “minimal use” or “smooth, coordinated use” of any rudder input. Contrary evidence indicated that at least once, earlier in this pilot’s career, he may have used essentially the same control inputs (i.e., full or almost full rudder application) to, as he was reported to have said, “level the wings due to wake turbulence.” Of course, rudder deflection will cause a rolling moment, due to the sideslip that will develop (in fact, in some airplanes, particularly swept-wing airplanes, a competent aerobatic trained pilot may be able to “roll” the aircraft completely through 360 degrees, using only the rudder), but the rudder is not a roll-control device; and no one seems to know where this pilot may have picked up this particular control application impression.

I know very little about boats of any size – other than the fact that they are supposed to float – but your analogy and your conclusions seem to be pretty well on target. As you say, “you might well break the rudder off in a dinghy if you tried this.” And, it would seem that this situation verifies your concerns.

[bomarc]

dirty dingo

the question was only about the a300(a310) series of planes and not the a320 and later. that is a whole other discussion.

some people feel that this is a boeing vs airbus thing. it is not intended to be. I have no great fondness for the b 737 for example.
---
rainboe: I think that during a violent wake turbulence encounter the captain would be even more in tune with what the other pilot was doing...and if it all in disagreement with the copilots actions would use the time honored phrase: "I've got it".

As far as being hit with a newspaper...it is not one of my preferred instructional methods.

There does seem to be a valid point you make about knowing about over controlling a plane. No where in my 30 years of flying has anyone mentioned breaking apart an airplane by over controlling (referencing safe operating speeds) unless a specific limitation printed in the aircraft flight manual (sometimes called POH).

I have searched the flight manuals of 4 jets that I have flown and nothing about breaking the thing apart.

Now, perhaps you were taught something some of us weren't. Time to share the knowledge.
Perhaps we were taught something you don't know.

Learning to fly is still a bit of an art and not just a pure science.

==
bubbers 44, I have to agree with you.
-----
as far as using the rudder to "roll" the plane...I have used the rudder in a very gentle manner to initiate a slight bank at cruising speeds in a jet. It seems to work fine...but of course the ailerons/spoilers are the intended control for roll. rudder is the intended control for yaw...but yaw a plane and it might just bank.
;-)

[Rainboe]

From before I started passenger flying, I was taught in BOAC to 'go easy on the rudder', it is for engine failure, not for flying the plane. I was taught it at flying school- always be ginger on the rudder, it's not stressed to take misuse. Frankly it is so ingrained I cannot conceive of people using it like in this example. I have been caught flying along a 747 vortex after Canarsie on a Canarsie approach in a VC10. It took most aileron to hold it- I didn't touch the rudder. A pilot who thinks he can apply rudder control as in this case has controlled way outside design parameters and I consider has had a significant part of his flying education and experience missed or ignored. I'm sorry to be brutal, but no pilot flying a passenger jet should have missed this point. I know all my colleagues at a big British Airline have been brought up with this. We have had significant jet upsets for various reasons. All have apparently flown and recovered correctly and 'let it go' rather than bully the thing with overcontrol to get it to do what they desire. I think constantly trying to defend the indefensible and plead ignorance will not instill confidence in the flying public.

[cornwallis]

I have flown almost all the airbus line apart from the 340.I have also flown the 737/757 and the nicest aeroplane I have ever hand flown is the 300.It has a good roll rate and is light but I have never used the rudder in normal flight apart from engine failures.The roll spoilers and aileron are more than enough to pick up a dropped wing.I always felt that the 320 family could be a bit slow in this.
Most instruction I have seen about recovering from upsets advised to roll to the blue-it never advocated rudder inputs.

[bomarc]

dp davies admonishes us not to use the rudder in certain turbulence conditions.

however we must ask ourselves about being taught to use rudder in certain situations as part of a recovery. indeed, since the tragic crashes in pittsburgh and colorado springs involving the 737 hardover, new methods have been introduced...these started about 1995 to my memory.

if one limits the use of rudder to engine out and crosswind landings, leaving it on yaw damper for the express purpose of countering "dutch roll" fine.

but it is not being taught that way...and no specific mention of NOT using the rudder is being made at many large and respected airlines.

indeed in certain wake turbulence encounters, rudder and aileron/spoilers are part of the equation, at least according to some schools of thought at some major airlines in the us.


may I suggest, what has been suggested before, that since American's primary aircraft is the MD80 (super 80) a mindset might have evolved that what was good for the MD80 was good for everything else. And perhaps it is not so.


Indeed, for the record, since 1935 in the US, Rudder has been a vital part of the controls. It is said that a CAB test pilot took off in a plane that had the ailerons rigged backwards and used the rudder to land and since that time the rudder was part of the equation.

in 1982 my ailerons failed inflight on a small aircraft and rudder is what I used to land the plane safely.

We have all learned in different ways how to fly, how our decision making process is influenced by how and what we have learned in the past.


good luck to us all

[Casper]

Has it been officially proved (and beyond doubt) that rudder hardover was a factor in Colorado Springs and Pittsburgh?

[JustAnothrWindScreen]

dear rainboe:
would the airbus 300 series be your first choice in planes to fly? you may choose from any plane currently flying, comparing it to the above plane?
hypothetical of course.

Bomarc,

Hypothetically, I could have bid the B777/A300/B767/B757. Before this accident, I really had no problem with any of them. After the accident and talking with numerous A300 drivers, my choice went to the B767/B777 and bypassed the A300, hypothetically speaking of course. Airbus/Boeing was never one of my criteria, only rosters and QOL. I simply dropped the A300 from consideration.

[bubbers44]

Rainboe, We will never know for sure if Sten put the control inputs in that caused the failure or if it was already happening and he was just trying to keep it flying straight. I still don't think the captain would have allowed him to overcontrol to the point of structural damage for wake turbulence. I'm done.

[AirRabbit]

Rainboe, We will never know for sure if Sten put the control inputs in that caused the failure or if it was already happening and he was just trying to keep it flying straight. I still don't think the captain would have allowed him to overcontrol to the point of structural damage for wake turbulence. I'm done.
Two points - once again.

1) According to the FDR, the cockpit controls were not displaced in an effort to counter a control surface movement or to counter a vertical or lateral acceleration. The A-300 cockpit controllers (column, wheel, pedals) are not reversable controls. If the cockpit controllers were moved (and according to the FDR all three were moved - rather substantially and rather briskly), someone in the cockpit with access to the respective control moved it.

2) The entire episode, from the first controller movement to the end of the data feed was just under 9 seconds in duration. To say that the Captain, or anyone else for that matter, should have been able to observe what was happening, evaluate the cause, determine what was being responded to and how, recognize the adequacy or inadequacy of what was being done, decide on a course of action, and initiate that course of action - and do all that cold, with zero warning, and do it all successfully - is a mighty tall order for a mere human to grasp. I might point out that it probably took you 7 or 8 seconds to read that last sentence.

[misd-agin]

The A300 is a nice flying a/c. The accident made us aware of how sensitive the rudder is.

My comments using numbers (1-100) is just a subjective opinion to perhaps expand the understanding of what increased speed has on rudder inputs and is not based on engineering data.

To fly, or not fly, the A300 for my personally has nothing to do with the accident. My experience is that Boeing products(757/767/777) are more reliable than the A300 but if my schedule was better on the A300 I'd fly it.

I believe the AAMP program developer was on the 757/767 when the program was developed. Numerous profiles were flown, by qualified pilots in the different a/c AA flew, so the AAMP wasn't developed using the S-80 as the baseline.

[AirRabbit]

Has it been officially proved (and beyond doubt) that rudder hardover was a factor in Colorado Springs and Pittsburgh?
As far as I know, the answer to your question is "no." However, the circumstances do point, quite heavily, toward rudder involvement.

The significant point, however, does not necessarily stop at understanding the rudder implications. In both of these cases, the crew was at a relatively slow airspeed and the indications were that they tried to slow even further. There is a phenomenon called "cross-over speed" that comes into play in circumstances such as these. This is where, at a given speed, the rudder and the ailerons are equally effective in controlling the roll of the airplane. Below that speed, the rudder becomes even more effective in that control. Above that speed, the ailerons become more effective. In both of these cases, there is a reasonable likelihood that, had the crew accelerated to something above that "cross-over" speed, they would have been able to recover, even WITH the existing rudder problem thought to exist.

[Casper]

Thanks, AirRabbit. That is interesting info. Boeing "suggested" that the amendment to the B737 QRH re rudder problems was effected due to "politics."

I was also under the impression that some local weather factor (mountain waves) may have contributed to the Colorado Springs accident.

[bomarc]

casper

as the builder of the part of the rudder actuator has taken the lion's share of the liability in the pittsburgh crash, and that the FAA has mandated that there be a "fix" to the rudder problem ( in this case a radio altimeter input to reduce hydraulic pressure to the rudder above 700'agl) I think that we can gather that the rudder was the problem.

as to mountain wave in the colorado springs tragedy, it is up to you to decide for yourself.

I've decided that the rudder is a POS

[AirRabbit]

as the builder of the part of the rudder actuator has taken the lion's share of the liability in the pittsburgh crash, and that the FAA has mandated that there be a "fix" to the rudder problem ( in this case a radio altimeter input to reduce hydraulic pressure to the rudder above 700'agl) I think that we can gather that the rudder was the problem.
Yes, the rudder pressue is reduced to about half - unless there is an engine problem during takeoff. If that happens, the reduction does not occur. But as for "gathering that the rudder was the problem," that may be going just a bit far. Here is link to an FAA document that was published approximately 6 years ago. The contents of this FAA Bulletin contain a lot more of the detail in what was decided and how the facts were going to be dealt with regarding the B-737 "rudder issues." You can judge for yourself.
http://www.faa.gov/library/manuals/examiners_inspectors/8700/fsga/media/Fsga0009.doc
as to mountain wave in the colorado springs tragedy, it is up to you to decide for yourself.
I'd go along with that recommendation.
I've decided that the rudder is a POS
I'm sure we're all glad to know of your decision.

[JustAnothrWindScreen]

2) The entire episode, from the first controller movement to the end of the data feed was just under 9 seconds in duration. To say that the Captain, or anyone else for that matter, should have been able to observe what was happening, evaluate the cause, determine what was being responded to and how, recognize the adequacy or inadequacy of what was being done, decide on a course of action, and initiate that course of action - and do all that cold, with zero warning, and do it all successfully - is a mighty tall order for a mere human to grasp. I might point out that it probably took you 7 or 8 seconds to read that last sentence.

Thats what airline Captains do all the time and is not a tall order for a mere human. When you look at your watch, 9 seconds is an eternity.

[Rainboe]

Yes, but the point seems to be missed that during a sudden violent distraction, such as a serious wake encounter, it is perhaps understandable if the Captain's attention is distracted for a short time away from what is happening hidden from view in front of the control column His feet wouldn't be riding the rudder pedals as the copilot was flying, so there would be no tactile feedback.

[DozyWannabe]

Thanks, AirRabbit. That is interesting info. Boeing "suggested" that the amendment to the B737 QRH re rudder problems was effected due to "politics."
They also spent a considerable amount of money coming up with their own report saying that the crashes were both likely to be a result of pilot input rather than a design fault with the rudder system - aren't corporate lawyers great?
I was also under the impression that some local weather factor (mountain waves) may have contributed to the Colorado Springs accident.
It's plausible, but I'd have thought that a strong mountain rotor would have caused a mid-air breakup as with the BOAC 707 Mt. Fuji incident, rather than forcing the aircraft into the ground intact as happened in Colorado Springs.

Pointless speculation here, but the problem was with the PCU, which could jam and send the rudder into a hardover in the opposite direction to that commanded by the pilot. I've wondered for a while whether both those aircraft encountered some kind of turbulent air and when the rudder was used to correct, the PCU jammed and this 'reverse hardover' defect came into play.

Either way we're drifting off topic, although it's useful to note that no manufacturer is happy about admitting their arcraft has a fault.

[Graybeard]

Yes, but the point seems to be missed that during a sudden violent distraction, such as a serious wake encounter, it is perhaps understandable if the Captain's attention is distracted for a short time away from what is happening hidden from view in front of the control column His feet wouldn't be riding the rudder pedals as the copilot was flying, so there would be no tactile feedback.
Tactile feedback was in his butt.

GB

[bomarc]

air rabbit

if the rudder wasn't the problem on the 737 pit and cos, then:

why is there so much training in rudder hardover recovery for this plane?

why are there now memory items for turning off the hydraulic power to the rudder?

why is there a pressure reduction mechanism?

why are crossover speeds so vital a part in flying the plane now?


believe me, it is much easier a plane to fly with the old "speeds", (except for the lack of rudder hardover protection)
=================================================

I know people who actually believe that both crashes were completely pilot error.

Perhaps these are the same kind of people also would blame the pilots for the electra crashes in the 50's.
----------------------------------------------------------------

and yes to the chap who mentioned corporate lawyers! they do earn their money.

I went to the NTSB hearing in the DC area (near the springfield shopping mall for those familiar with the area).


One thing that did come out was that more recent standards of certification would indicate that the 737 in its present form would not have been certified.


Could this concept be useful with the airbus 300?

[barit1]

Nor could the DC-3, in original or present form, be certified. This proves nothing except that cert stds change from time to time. Does this surprise anyone?

[AirRabbit]

Thats what airline Captains do all the time and is not a tall order for a mere human. When you look at your watch, 9 seconds is an eternity.
Without trying to be overly critical of your opinion, I think that all of us would like to believe our own “press:” Supermen (and women), highly trained, laser-like mind, inerrantly finding the problem and whipping out a weird, but effective, solution. Would that it were so … but James Bond is still a fictional character.

Your characterization of 9 seconds being an eternity is, as I’m sure you recognize, a relative perception. Pointing up that relation is a pretty “standard” attorney response when a witness says “I only got a very brief view of the murder – only about 9 seconds.” The attorney calmly asks the jury to see how long 9 seconds really are … “Ladies and gentlemen, I’m going to ask you to hold your breath when I say ‘now’ and to hold it until I say ‘ok’ at the 9 second mark, and we’ll see just how long 9 seconds really is.” As Einstein once described, “When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity.” The timing involved here is just as “relative.”

If you look at the animation of the FDR, the first couple of control applications and reversals (time marker 15:51 through 15:54) probably didn’t get the airplane terribly “out-of-sorts” with itself – at least to the point that the Captain would have immediately suspected the F/O was about to tear the tail off the airplane – and that is why the Captain asked “You alright?” in response to the F/O’s request for “max power;” which was said some 3 seconds into the “less than 9-second” ordeal. Again, view the animation of the position of the airplane during this brief period. Note how far the airplane animation actually moves. In calm air, this movement would probably be noticeable; but having just experienced an encounter with a wing-tip vortex, I don’t think the second encounter was a surprise – and certainly not one of ominous proportions. However, it is more than likely that, even without an immediately recognizable “tactile impression” of danger in the cockpit (despite Graybeard’s comment, “Tactile feedback was in his butt"), the damage was probably already begun.

The next couple of control inputs and reversals probably DID get the attention of the Captain, but the response of the F/O, “Yeah, I’m fine” would have likely given the Captain reason to pause in his judgment, and additionally, the Captain was very likely evaluating and/or attempting to comply with the F/O’s request for “max power.” Immediately thereafter, he was either directing or encouraging the F/O with his comment “hang on to it, hang on to it.” It was at that moment that the airplane started a rather sizable yaw moment to the left – and there is very little doubt that the Captain would have missed that movement – however, I think THAT was the final straw, and the vertical stab departed the airplane. The time markers between those points are 15:57 and 15:59 – after which the data feed stops.

The Captain was not sitting in isolation, pre-loaded to see, recognize, and respond to a problem – particularly one of the magnitude that was developing. He observed and challenged; and he got what was likely determined to be a reasonable response. But from there it went down hill with the burners full on! I am as sure as I can be that these guys did not feel this scenario was unfolding over some lengthy time period.
They also spent a considerable amount of money coming up with their own report saying that the crashes were both likely to be a result of pilot input rather than a design fault with the rudder system - aren't corporate lawyers great? .
Yes, this is true; but would you expected to have Boeing, or anyone else for that matter, say, “Yep. Guilty. We’ve built the world’s most unsafe airplane.” I suspect that they were trying to walk the very fine line between telling the unbridled truth and perhaps scuttling the company; and out-right lying by claiming that there isn’t, and could not be, anything wrong with the airplane. I don’t believe either of those two extreme positions were accurate. It may well be that the engineers at Boeing don’t even know for sure, what the no-sh*t reason was behind those crashes. However, that the rudder was involved in some way is very hard to argue against. But, if you don’t know (or can’t admit) how do you address the situation?
Pointless speculation here, but the problem was with the PCU, which could jam and send the rudder into a hardover in the opposite direction to that commanded by the pilot. I've wondered for a while whether both those aircraft encountered some kind of turbulent air and when the rudder was used to correct, the PCU jammed and this 'reverse hardover' defect came into play. .
I suspect that laying the responsibility on the PCU was a reasonable route to follow. Was it the REAL cause? I don’t know. My guess is that Boeing would say that it was prudent to re-address the rudder control issues from top to bottom, including the PCU. In fact, I think that is exactly what they DID say – or something close to that.
Either way we're drifting off topic, although it's useful to note that no manufacturer is happy about admitting their arcraft has a fault.
My point as well.
air rabbit
if the rudder wasn't the problem on the 737 pit and cos, then:
why is there so much training in rudder hardover recovery for this plane?
To my knowledge, the training received by pilots flying the B-737 (all series) in addition to the systems taught in ground school, has to do with “cross-over” speeds – where slower airspeeds allow the rudder to be more effective at controlling roll and higher speeds allow the ailerons to be more effective at controlling roll. Therefore, if you have a rudder/roll problem, accelerate to above the cross-over speed to be able to control the roll with the roll control for the airplane, the ailerons.
why are there now memory items for turning off the hydraulic power to the rudder?
Because it makes good sense. If there is any possibility that a powered rudder is causing or exacerbating an existing problem, it would be prudent to eliminate the powered rudder input.
why is there a pressure reduction mechanism?
Because it makes good sense. Even if the existence of a powered rudder had nothing to do with the accidents, it would be good press to take the extra steps to include a rudder pressure reduction system – and, it would be like chicken soup – it couldn’t hurt – particularly if the system prevents pressure reduction in those cases where having the rudder powered is a good thing – like on an engine failure during takeoff.
why are crossover speeds so vital a part in flying the plane now?
I don’t think that cross-over speeds are any more vital now than they used to be. It’s just that more people are more aware of what they are, what they mean, and how that knowledge may be able to save your butt.
believe me, it is much easier a plane to fly with the old "speeds", (except for the lack of rudder hardover protection)
Well, I’m not terribly sure about that. I fly the B-737 and it’s like any other change made to an airplane. IF you were aware of what cross-over speeds were, how they affected the handling characteristics of the B-737 (or any other airplane for that matter), and used that knowledge if or when necessary, I’m not sure that a so-called “rudder hardover” would be a problem.
I know people who actually believe that both crashes were completely pilot error. Perhaps these are the same kind of people also would blame the pilots for the electra crashes in the 50's.
Yes, I’m sure that is true. There are also people who believe that it was a Tomahawk missile that crashed into the Pentagon on 9/11. There are others believe that extraterrestrial aliens are roaming the streets of Roswell, New Mexico. Maybe they should all get together and have a picnic?
and yes to the chap who mentioned corporate lawyers! they do earn their money.
Sometimes they do. Sometimes they don’t.
I went to the NTSB hearing in the DC area (near the springfield shopping mall for those familiar with the area). One thing that did come out was that more recent standards of certification would indicate that the 737 in its present form would not have been certified. Could this concept be useful with the airbus 300?
Are you saying that the “new” certification standards would not allow for the B-737NG to be certificated? And, I’m sure you’re aware that current standards wouldn’t allow many airplanes still flying to be certificated either. So, what would be your recommendation? Ground them all?

[DozyWannabe]

Yes, this is true; but would you expected to have Boeing, or anyone else for that matter, say, “Yep. Guilty. We’ve built the world’s most unsafe airplane.” ... But, if you don’t know (or can’t admit) how do you address the situation?
You're absolutely correct sir. As I stated below, I don't think any manufacturer would do that, and in fact it would probably have a negative impact of safety were the company to be scuttled rather than a fix found.

I just mentioned it to counteract the opinions of those who think that kind of behaviour is strictly a French or Airbus thing.

I suspect that laying the responsibility on the PCU was a reasonable route to follow. Was it the REAL cause? I don’t know. My guess is that Boeing would say that it was prudent to re-address the rudder control issues from top to bottom, including the PCU. In fact, I think that is exactly what they DID say – or something close to that.
Correct again. I've never disagreed with the PCU being the primary failure point. My speculation was purely on the basis of the PCU failing during an attempt to recover what was up until then a normal weather or wake encounter. The Seattle Times report suggested that Boeing may have known that there was something not quite right with the setup when a 747 elevator assembly (using the same or similar components) was reported as misbehaving some time before the 737 accidents occurred.

It just depresses me when I read things like 'What A French POS' regardless of the source, simply because while such statements are obviously provocative rather than helpful, it means that out there, someone does believe that to be the case. For all talk of lack of robustness, the only airliner to survive a missile strike and make a successful landing with a significant portion of the trailing edge of the wing missing, almost up to the aft spar, was an A300.

[airsupport]

Yes, I’m sure that is true. There are also people who believe that it was a Tomahawk missile that crashed into the Pentagon on 9/11. There are others believe that extraterrestrial aliens are roaming the streets of Roswell, New Mexico. Maybe they should all get together and have a picnic?


Good idea.

At that picnic I would like to see just how many people believe as I do, that this crash had little to do with the Pilots, rather it was caused by a design flaw with the composite structure, weakened by the continual ingress of water into it because of the routes it operated.

Still we can't have all A300/A310s grounded, better to blame the Pilots.

[bomarc]

barit one

you mentioned the dc3...how many of those came apart in flight due to pilot over controlling the rudder?

I think the dc3 would be easier to certify now than the current 737...

and AIR SUPPORT

see you at the picnic!~ and let's be sure to use safe food handling and avoid food poisioning!

us skeptical pilots are getting rarer and rarer. ;-)

and air rabbit...9 seconds is a long time for an experienced airline pilot. about 6 seconds pass from crossing the threshold of a runway to touchdown on a normal landing ( 50' over threshold, 500 fpm descent...you do the math)

and alot happens there. I've certainly taken over from an inexperienced or screwing up copilot in less time than that. I'll bet air support and others have too.


all of you who think it was the pilot...welcome aboard the airbus 300! all 34 in pax service in the usa.

all of you who think that the pilot was shafted...you have lots of other choices!

[DozyWannabe]

Obtuse doesn't even begin to describe it. :ugh:

For the last time:

- No-one placed the sole cause, let alone blame, on the pilot.
- The most documented cases of composite fatigue happened on the Concorde, and as a result of that, new techniques of scanning for failures were developed. This is not an unproven technology.

http://www.newscientist.com/article/mg19125673.200-composite-planes.html

- The loads placed on the vertical stabiliser exceeded design limits (proven beyond reasonable doubt) and even a metal rudder would likely have failed in that situation.

[airsupport]

as a result of that, new techniques of scanning for failures were developed.

Interesting choice of words, they MAY have been "developed" I don't know, but they certainly were NOT in use at the time of this accident.

Our Company operated an Airbus A300 similar to the one that crashed, also based at JFK NY, and also flying primarily down through the Caribbean.

During the 12 months it was based at JFK, the ONLY inspection required (and carried out) to the composite tail was just an external visual inspection.

Combined with this, at every maintenance overnight at JFK, it would take all night to drain the water that was trapped in the tail.

After this terrible accident happened, and having previously seen these inspections, I still wonder if although the desperate actions of the Pilots that tragic day MAY have been what finally snapped it off, the composite structure may well have been degraded dangerously and nobody would have known.

Most accidents in Aviation are a combination of things, rarely if ever one cause.

[DozyWannabe]

After this terrible accident happened, and having previously seen these inspections, I still wonder if although the desperate actions of the Pilots that tragic day MAY have been what finally snapped it off, the composite structure may well have been degraded dangerously and nobody would have known.
http://www.ntsb.gov/events/2001/AA587/presentations/04_materials.pdf

The NTSB did a full fractographic and electron microscope scan of the surface of the vertical stab and there was no dangerous level of fatigue observed.

Another aircraft in the AA fleet showed signs of disbonding, but this did not make it dangerous.

J.

[airsupport]

Again an interesting choice of wording.

The NTSB did a full fractographic and electron microscope scan of the surface of the vertical stab and there was no dangerous level of fatigue observed.

Someone decided days after the accident, after the tail had been in the water, that there was no "dangerous" level of fatigue, and by ONLY scanning the surface. It is NOT the surface I was concerned about, but the structure and attachments etc.

We just had a strong wind here, which sadly (not really true) snapped off and brought down on our house a big old gum tree. The wind brought the tree down, however I think the tree was rotten through and through, and it was only a matter of time before we had a strong wind.

I would get the NTSB to carry inspections to determine the cause of this disaster, but why bother, they will only spend a fortune looking at the bark of the tree, find nothing wrong with the bark, and blame the wind.

[barit1]

I think (but cannot say for sure) that the "surface" referred to by NTSB is the fracture surface. That's the surface the material science people are interested in.
See the early NTSB releases from last year's Chalk's G-73T crash - they included photos (http://www.ntsb.gov/Pressrel/2005/051222a_2.jpg) of the lower spar cap fracture surface.

[AirRabbit]

air rabbit...9 seconds is a long time for an experienced airline pilot. about 6 seconds pass from crossing the threshold of a runway to touchdown on a normal landing ( 50' over threshold, 500 fpm descent...you do the math)
and alot happens there. I've certainly taken over from an inexperienced or screwing up copilot in less time than that. I'll bet air support and others have too.
all of you who think it was the pilot...welcome aboard the airbus 300! all 34 in pax service in the usa.
all of you who think that the pilot was shafted...you have lots of other choices!
With all due respect, I am not trying to get into a "one-upsmanship" debate with you. There are quite a few experienced airline veterans here - and I'm sure that more than a fare share of us have "taken away" an airplane from an inexperienced pilot or one who was in the process of "screwing up," as you say.

But, there are times when things ... happen. As I have said many, many times on this thread - I do NOT desire to lay at the feet of the AA First Officer any more of the responsibility for this particular accident than is deserved. I am sure he was a responsible, well-trained, competent, young man, doing his dead-level best to perform honestly and safely. BUT, as I have also said, many, many times on this thread - he WAS at the controls. He DID make those control inputs - or the Captain did. There isn't any other option. When control inputs of that magnitude are made and are almost instantly reversed with equal magnitude, over and over again ... the aviation community has no business attempting to find fault with the structure of the airplane. If the airplane WAS, indeed, structurally inferior or damaged, so be it ... but I have yet to hear from any responsible aircraft structures expert who believes that such control input/reverse, input/reverse, repetitions would NOT have similar consequences regardless of the aircraft involved. The problem that I see is that after having the critique from the B-727 Captain with whom this young man had flown, regarding the ill-advised use of rudder to control the roll that developed after encountering turbulence, that young man or someone responsible for his training, should have revisited at least his training and perhaps queried others regarding the same issues. Of course, hindsight is always better focused – and perhaps the circumstances didn’t rise to that level of concern at that time. If true, it certainly is regrettable – as such a misunderstanding about control application can be rather easily corrected with proper education, training, and procedures.

Sometimes Captains get "caught" in the process of letting a responsible and competent F/O continue to fly the aircraft. As evidence, I would submit the following quote from an NTSB report …
In December, 2003, after final approach into Memphis, the First Officer allowed the airplane to to land so hard that the right main landing gear collapsed and the airplane veered off the runway. The aircraft burst into flame.
The airplane had been in a left crab, but was lined up momentarily with the runway, albeit to the left of the centerline, moments before touchdown. However, the flight data recorder (FDR) indicates that the airplane was a bit high and that the aircraft experienced an unusually high vertical speed. As a consequence, the right main landing gear experienced a vertical speed of 14.4 feet per second (fps). This was more than the 12.5 fps experienced by the left main landing gear. The design limit was 10 fps, and the demonstrated reserve energy was 12.0 fps, which the right gear clearly exceeded.
The gear collapsed during the landing rollout, and the plane fell into its right wing, where friction with the ground pulled it to the right and off the runway.
NTSB investigators attribute the accident to improper crosswind and flare techniques by the first officer and the captain's failure to take corrective actions. "The captain remained silent as the approach deteriorated," said NTSB Capt. Dave Kirchgessner. Yet there were signs that the first officer was not coping well, among them that the aircraft was in a left crab and drifting, that control inputs were not sustained, and that there was no flare, he said. The flight, Flight 647, was a check ride for the first officer, who had experienced an altitude deviation on a previous flight. Her technique was being evaluated by the captain, who was serving as both check airman and pilot in command.
As I said, sometimes Captains get "caught" in the process of letting a responsible and competent F/O continue to fly the aircraft, even when the Captain is there specifically to determine IF the F/O IS responsible and competent.

[airsupport]

I think (but cannot say for sure) that the "surface" referred to by NTSB is the fracture surface. That's the surface the material science people are interested in.
See the early NTSB releases from last year's Chalk's G-73T crash - they included photos (http://www.ntsb.gov/Pressrel/2005/051222a_2.jpg) of the lower spar cap fracture surface.

IF that is what they mean, why don't they say that.

I guess because they want to make the report as ambiguous as possible, and aid in the cover up of the facts.

I will mention this at the picnic. ;)

[AirRabbit]

Good idea.
At that picnic I would like to see just how many people believe as I do, that this crash had little to do with the Pilots, rather it was caused by a design flaw with the composite structure, weakened by the continual ingress of water into it because of the routes it operated.
Still we can't have all A300/A310s grounded, better to blame the Pilots.
So, am I to conclude from your comment that you believe the aileron and rudder control input and reversals, to the same maximum deflection as occured on this aircraft, if occuring on any other aircraft, would have been transparent and non-eventful?

I am not a structures expert by any stretch of anyone's imagination, and I know even less about composite structures; but, if your allegation has any merit, wouldn't it be true that other, similarly constructed aircraft, subjected to similar routes with similar frequencies, would be found to have the same type of structural weakening you describe?
IF that is what they mean, why don't they say that.
I guess because they want to make the report as ambiguous as possible, and aid in the cover up of the facts.
As typical of such report, this one contains “factual statements.” My experience with NTSB accident reports are that they don’t go into overly lengthy explanations when a detailed and scientific concept is being used in the analysis – presuming that those who are interested either know the scientific and engineering concepts involved or will research on their own so as to be able to understand the rationale behind their conclusions.

I guess I just have a problem with those who continue to deny observable, incontrovertible facts … facts that are evident to anyone … in preference for a belief that professionals, with no personal or professional motivation, are attempting to “cover up” a sinister problem that, were it to exist, is likely to raise it’s ugly head again in the future and cost additional lives and untold damage.

[Few Cloudy]

Sorry to hark back to the dark ages but when I trained on the Victor K1 (one of the first big 4 jets for our American colleagues) which was very sweptback with its sickle shaped wing, we had two yaw dampers - hydraulic and electric - one as a backup. The Victor at altitude was very easy to overcontrol, in all axes and steep turns for instance could be a nightmare for a new pilot.

During training the two YDs were often selected Off and a demo Dutch roll was allowed to develop. We than had to stop it but Never with the rudder! You waited until the wings went through the horizontal and then put in an opposite aileron input to the direction of roll. On the roll back you did the same again and after about three oscillations she was under control. Of course some people did try to use the rudder because it was after all the Yaw damper which had been switched Off and those people got into great big problems - far from damping out the oscillation. they aggravated it because the rudder was far too powerful a control for a human to make the tiny and timely corrections required, as the YD did.

Later in life (sorry for the history lesson) I did some maintenance test fliying which involved stalling the aircraft (MD-80). This was about the only time I have used the rudder in flight and that was if one wing stalled before the other, causing a wing drop. Out of roll aileron has the effect of increasing the AA on the dropping wing, so it stalls even more. The way out is a very careful single gentle application of rudder to engender a secondary effect of roll, at the same time getting on with the stall recovery ASAP.

Now you can´t compare that to rudder reversals and we were of course at a very low IAS but even there that barn door was hugely powerful. It needs a lot of respect and that message needs to be got over to each new generation of trainers and students.

It aint a Pitts.

[airsupport]

So, am I to conclude from your comment that you believe the aileron and rudder control input and reversals, to the same maximum deflection as occured on this aircraft, if occuring on any other aircraft, would have been transparent and non-eventful?

I am not a structures expert by any stretch of anyone's imagination, and I know even less about composite structures; but, if your allegation has any merit, wouldn't it be true that other, similarly constructed aircraft, subjected to similar routes with similar frequencies, would be found to have the same type of structural weakening you describe?

PLEASE do NOT make your own conclusions based on what I said, however to answer your 2 questions, question #1, IF by "any other aircraft" you mean other than an A300/A310 then yes, this problem is only on them, not even other Airbus models. Question #2 is a little harder because of the way you asked it, there is NO "similarly constructed aircraft", this problem is unique to the A300/A310, and yes the routes seemed to play a part in it.

I can only speak of what was happening around the time of this tragic accident, hopefully Airbus have modified the aircraft by now, I really don't know as I am no longer involved with the A300/A310.

At the time of this accident I do KNOW that there was nothing more than a brief visual external inspection of the tail carried out on in service A300/A310s, and that on A300/A310s operating out of JFK and down through the Caribbean there was always this massive amount of water trapped in the tail, which obviously used to freeze and thaw on each flight until it was eventually drained during a maintenance check.

Hopefully both of these things are now improved.

[AirRabbit]

...however to answer your 2 questions, question #1, IF by "any other aircraft" you mean other than an A300/A310 then yes, this problem is only on them, not even other Airbus models.
Well, if you can provide anyone with some expertise in aircraft structures who will agree with you that the same aileron and rudder inputs (maximum deflection and maximum reversals, both rudder and aileron -- I think there were 7 of them in 9 seconds -- at the same or similar airspeeds) would be totally transparent and non-eventful on "any other aircraft, not even other Airbus models," I'll back away.

[airsupport]

Well, if you can provide anyone with some expertise in aircraft structures who will agree with you that the same aileron and rudder inputs (maximum deflection and maximum reversals, both rudder and aileron -- I think there were 7 of them in 9 seconds -- at the same or similar airspeeds) would be totally transparent and non-eventful on "any other aircraft, not even other Airbus models," I'll back away.

I really couldn't care less whether you back away or not.

Just PLEASE stop twisting what I say.

I am NOT talking about how to fly or not fly the A300, and I am certainly NOT accusing anyone of anything (that should please Danny), however after being based at JFK NY with an Airbus A300 operating throughout the Caribbean, and seeing this lack of anything but a token external visual inspection of the composite tail, and this water that was always trapped in the tail for weeks on end, I just cannot help thinking that these could have been factors in this tragic accident.

The exact type of composite tail on the A300s in question is unique to ONLY the A300/A310.

Also, as I said, I am sure Airbus now have a better inspection schedule and have fixed the drainage problem.

[AirRabbit]

I really couldn't care less whether you back away or not.
Just PLEASE stop twisting what I say.
I am NOT talking about how to fly or not fly the A300, and I am certainly NOT accusing anyone of anything (that should please Danny), however after being based at JFK NY with an Airbus A300 operating throughout the Caribbean, and seeing this lack of anything but a token external visual inspection of the composite tail, and this water that was always trapped in the tail for weeks on end, I just cannot help thinking that these could have been factors in this tragic accident.
The exact type of composite tail on the A300s in question is unique to ONLY the A300/A310.
Also, as I said, I am sure Airbus now have a better inspection schedule and have fixed the drainage problem.
OK, friend; don't hyperventilate; I have no interest in “twisting” anything – particularly what you have to say. I thought that when you said, “this crash had little to do with the pilots,” you meant that the pilots had little to do with the crash. I was merely reading what was posted. If you are not talking about how to fly or not fly an Airbus A-300, then apparently you and I are talking two different problems. OK, fine. I know nothing about the water drainage issues on the subject aircraft. Perhaps this was a situation peculiar to the A-300/A-310 aircraft – and I certainly have no problem in yielding to your familiarity with those circumstances.

My comment was strictly related to the cockpit control inputs made during the last few seconds of the FDR recordings of AA587. As I said, the cockpit control inputs recorded on the FDR would have done serious damage to any aircraft – regardless of what the structure was – composites, weakened composites, aluminum, stainless steel, or wet cardboard – and that is all I was saying.

[411A]

...may well have never been even remotely aware of the consequences of using the powered rudder aggresively at higher speeds.
They positively know NOW.
Was the concerned pilot in error?
Most certainly.
But, even more importantly, so was the concerned aircarrier, American Airlines (aka, the Sky Gods) for developing an advanced maneuvering program involving abrubt full rudder movements at high(er) speeds, and the FAA inspectors for approving it.
Abrupt full rudder movements repeated at high speeds are absolutely to be avoided, least you want to have an even longer career flying heavy jet transports.
The older guys were taught...now clearly, the younger guys now know, especially at AA.:ugh:

[AirRabbit]

...may well have never been even remotely aware of the consequences of using the powered rudder aggresively at higher speeds.
They positively know NOW.
Was the concerned pilot in error?
Most certainly.
But, even more importantly, so was the concerned aircarrier, American Airlines (aka, the Sky Gods) for developing an advanced maneuvering program involving abrubt full rudder movements at high(er) speeds, and the FAA inspectors for approving it.
Abrupt full rudder movements repeated at high speeds are absolutely to be avoided, least you want to have an even longer career flying heavy jet transports.
The older guys were taught...now clearly, the younger guys now know, especially at AA.
Well, what you allege here is not accurate. If you look at the AA "Advanced Maneuver Training" package you will find that references to the use of the rudder never advocate alternating rudder input and always reflect the premise that rudder inputs should be smooth and coordinated; never do they call for “abrupt full rudder movement,” particularly at high airspeeds. So, other than the fact that they DO discuss the use of rudder in this program (and the rudder is an important and an effective aerodynamic control fixture), on the surface, at least, there would be no real reason to be critical of the program as written. That being said, what would you condemn about the FAA review and approval of such a program? On the other hand, and where only AA instructor and line pilot personnel are truly knowledgeable, the question clearly becomes, “what are the pilots trained to do when actually alone in the simulator?”

On the other side of the coin, there are major airline training programs that advocate the use of aileron only as the initial control input (in response to the yaw-induced roll) when experiencing an asymmetrical thrust situation; i.e., an engine failure on takeoff. In one program at least, while not in the text of the program, it is explicitly discussed in flight training that use of the rudder should be delayed, and the application of rudder should be made toward the “down side” of the control wheel (to ensure the correct rudder is applied), and to use only enough rudder to allow the wheel to “center.” Clearly, this is taking an extreme opposite position on the use of rudder controls – and in the mind of many – is still not addressing the reason that a rudder is on an airplane in the first place … that being to maintain coordinated flight.

[Rainboe]

I'm interested in why these rudder reversals took place, and what caused this pilot to think this was a valid way of controlling the aeroplane in a violent wake encounter. I think most pilots would 'let it ride' the immediate drama knowing it would only last a few seconds, and then take gentle corrective action afterwards to restore normal flight. I cannot imagine what he was doing thinking you can make large rudder inputs, then reverse them an instant later, then reverse again. It seems to be using a sledgehammer control input, because a wide bodied Airbus doesn't encounter such variable external influences at that rate- not at that rate where it can be identified what is happening and what corrective action should be taken. It is a flying technique that doesn't belong on anything bigger than a Pitts- it is most certainly no way to handle a large aeroplane.
The whole accident comes down to either
-a fatal fin defect causing it to come off in flight, or
-a fatal flying technique by the pilot.
If it is going to be suggested the first is the case, it is inevitable that the pilot inputs should be examined, and this pilot technique is what causes so much disquiet. Pleading ignorance that such a technique may be disastrous is no excuse when the vast majority of pilots are apparently aware of the problems rapid rudder reversals can cause. How on earth can any pilot believe such a technique is viable, unless he believes he must forcibly bully the aeroplane to do exactly as he wishes? Water in the fin or not, there has been shown to be no fatal design flaw in Airbus fins, so it was operated outside design parameters. The flight recorder showed why the fin failed under overcontrol. So why did the pilot fly like this?

[Loose rivets]

As I monitor this thread, I still have an uneasy feeling about the chicken and egg logic of the argument. To quote myself.

How sure are they, that the FP's input was not increasing because of an already developing structural failure?
The feedback may have been so modified, that he was reaching further and further for a familiar response.

This still nags at my thinking on the subject.

[JustAnothrWindScreen]

But, even more importantly, so was the concerned aircarrier, American Airlines (aka, the Sky Gods) for developing an advanced maneuvering program involving abrubt full rudder movements at high(er) speeds, and the FAA inspectors for approving it.
Abrupt full rudder movements repeated at high speeds are absolutely to be avoided, least you want to have an even longer career flying heavy jet transports.

Seems like someone touched a nerve here. Please tell me where American Airlines training program used abrubt (sic) full rudder movements at high(er) speeds and what department of the FAA approved this section that I cannot find? I have looked for that section but still have not found it. Why such venom?

[JustAnothrWindScreen]

Without trying to be overly critical of your opinion, I think that all of us would like to believe our own “press:” Supermen (and women), highly trained, laser-like mind, inerrantly finding the problem and whipping out a weird, but effective, solution. Would that it were so … but James Bond is still a fictional character.


I guess we will have to agree to disagree. "In my opinion" anyone that has flown high performance aircraft or have also flown captain on any of numerous commercial airliners do find that 9 seconds is a huge amount of time. Supermen, laser-like mind, whipping our a weird, but effective, solution, James Bond.... no not really, just a professional doing what they were trained and paid to do.

[DozyWannabe]

As I monitor this thread, I still have an uneasy feeling about the chicken and egg logic of the argument. To quote myself.
How sure are they, that the FP's input was not increasing because of an already developing structural failure?
The feedback may have been so modified, that he was reaching further and further for a familiar response.
This still nags at my thinking on the subject.
Because according to the NTSB's scan of the fracture surface of the recovered section of the tail and attaching lugs, there was no pre-existing evidence of fatigue, and the only stress area was at the main point of failure. The loads engendered by the FO's control inputs were capable of making even an unfatigued tail snap because the 'Ultimate' design load was exceeded.

If the tail was suffering from dangerous levels of disbonding and or fatigue then it would have failed well before the point at which it did.

[AirRabbit]

Salient questions are raised by Rainboe and Loose rivets.
I'm interested in why these rudder reversals took place, and what caused this pilot to think this was a valid way of controlling the aeroplane in a violent wake encounter. The whole accident comes down to either
-a fatal fin defect causing it to come off in flight, or
-a fatal flying technique by the pilot.
The flight recorder showed why the fin failed under overcontrol. So why did the pilot fly like this?
I think to have a better understanding one would have to go back further into the F/O’s flying career. There is that one suspicious account when flying the B-727 where both the Captain and the F/E remember him being quick to use massive rudder applications in an attempt to either maintain or, perhaps, from his perception, regain, control of the aircraft after having encountered wake turbulence. Determining why this particular incident was not followed might be an interesting effort – but perhaps the Captain and F/E believed the issue was isolated and had been properly addressed. I would wonder if any instructor or check airman ever noticed similar tendencies from this young man. It would be interesting to find out from the instructor who administered the AA Advanced Maneuver Training to this F/O if he demonstrated any tendency to “over control” the rudder during that training.
As I monitor this thread, I still have an uneasy feeling about the chicken and egg logic of the argument. To quote myself.
How sure are they, that the FP's input was not increasing because of an already developing structural failure? The feedback may have been so modified, that he was reaching further and further for a familiar response.
This still nags at my thinking on the subject.
Of course one would have to acquire the services of a more experienced FDR reviewer than me, but from the animation of the FDR recordings, it is relatively clear that after the first several rudder applications the airplane was responding as it should – given the fact that the applications were full throw – and then reversed. The airplane was responding to the pilot’s inputs in all three axes – at least up to the time when the data feed ceases. I would think that any developing structural failure would have been noticed in either the airplane failing to respond to control input, OR it would have been responding to vertical fin/rudder displacements that were not called for by the pilot. However, neither of these situations is evident in the data available.
http://www.ntsb.gov/Events/2001/AA587/flight_path_web01.wmv

[barit1]

Forgive please if this is old news, but the initial releases of the CVR transcript included two episodes of a "rattling noise". Have these been sorted out?

[AirRabbit]

I guess we will have to agree to disagree. "In my opinion" anyone that has flown high performance aircraft or have also flown captain on any of numerous commercial airliners do find that 9 seconds is a huge amount of time. Supermen, laser-like mind, whipping our a weird, but effective, solution, James Bond.... no not really, just a professional doing what they were trained and paid to do.
Well, yes and no; and I certainly don’t mean to “step” on your opinion – you certainly have a right to disagree with mine.

Nine seconds certainly can be a huge amount of time – but, I believe it all depends on what happens during that time period. I would submit that when a 9-second window is divided into segments, where the first third of it is used to adequately address the issue at hand or, more properly, believe that the issue had been adequately addressed; taking another third of that window to verify that belief – that being the Captain’s query, “You alright?” and the confirmation from the F/O, “Yeah. I’m fine”; the balance of that window, at most a third, or 3 seconds, comes down to processing the “I’m fine” response while having the airplane’s tail ripped off. Again, I don’t think either of these two pilots were watching a series of controlled events unfolding very slowly and deliberately before their eyes.

Yesterday, I posted a quote from an accident report only to show that there ARE times when what would seem to be “adequate time,” for some reason, is not. In that accident, a Check Airman, serving as PIC, was assigned to a line flight to specifically observe a F/O for proficiency, and during a crosswind approach to landing where the F/O apparently showed signs of not coping well with the progress of the approach, allowed the F/O to establish a high rate of descent while still crabbed on the approach, failed to notice that the F/O did not maintain adequate control inputs for the situation, failed to take control of the aircraft when the F/O did not flare the airplane at the appropriate point, and allowed the airplane to land so hard that it collapsed the right MLG, dropping the wing to the ground, dragging the airplane off the runway. The report cited the improper crosswind and flare techniques by the F/O and the Captain’s failure to take corrective actions.

Where a case could easily be made on this landing accident that the Captain had every reason to believe the proficiency of the F/O may have been in doubt and, somehow, got caught either over thinking the problem or was over confident in his recovery abilities, I think exactly the opposite case can be made for the Captain of AA587. The AA587 Captain had no reason to be suspicious of his F/O’s proficiency. He observed the F/O successfully transition a wake turbulence encounter mere seconds beforehand. Whether or not the Captain had any idea of the magnitude of the cockpit control deflections the F/O used, we’ll probably never know, but as the situation didn’t resolve itself as quickly as the first wake turbulence encounter, he queried the F/O about how he was doing and was told “Yeah, I’m fine.” It was THEN that the fit-hit-the-shan!

[airsupport]

As I monitor this thread, I still have an uneasy feeling about the chicken and egg logic of the argument. To quote myself.


Quote:
How sure are they, that the FP's input was not increasing because of an already developing structural failure?
The feedback may have been so modified, that he was reaching further and further for a familiar response.

This still nags at my thinking on the subject.

Exactly my theory, which will also be discussed at the picnic. ;)

[bubbers44]

Wish I could be at the picnic. Did the A300 really have rudder inputs from the pedals like it showed in the video or did they just use rudder actuator inputs to the FDR to show what the rudder pedals would do to make the rudder move? My friend who had the uncommanded rudder movements didn't move his rudders and the yaw damper was throwing his airbus out of control trying to land in Miami. Does the Airbus really have rudder pedal movement in their FDR. Years ago I heard no. I just remember that TWA 800 video that showed them zooming up 1000 feet after the explosion and the nose falling off and lost confidence in their credibility of video reinactments. I dought that this video was accurate either. Feeling your captains seat being thrown around violently would cause any captain to fix it and say I've got it and take control if the FO was out of control. I think Sten was trying to fix a problem, not cause one. Wake turbulence is a non event, we encounter it every month or so. Has anyone experienced what it feels like to have a tail failing in flight? Probably a lot of fluttering and yawing.

[JustAnothrWindScreen]

I would submit that when a 9-second window is divided into segments, where the first third of it is used to adequately address the issue at hand or, more properly, believe that the issue had been adequately addressed; taking another third of that window to verify that belief – that being the Captain’s query, “You alright?” and the confirmation from the F/O, “Yeah. I’m fine”; the balance of that window, at most a third, or 3 seconds, comes down to processing the “I’m fine” response while having the airplane’s tail ripped off.

I have never personally reacted in the way you describe. Having said that, everyone does react in a different manner. Your description reminds me more of a monday morning lawyer trying to prove a point whether that is how things actually took place or not. Like I said earlier, we can agree to disagree.

[bomarc]

AIM 7-3-3 b.


in rare instances a wake encounter could cause inflight structural damage of catastrophic proportions.


===


food for thought, above from the US AIM.

maybe the votex hit the vertical stabilizer of the airbus "just right" to make it come off...and all the rudder pedal movements in the world just wouldn't matter after that.

see you all at the picnic! all the food for thought you can eat!

[misd-agin]

[quote=AirRabbit;3056370]

I think to have a better understanding one would have to go back further into the F/O’s flying career. There is that one suspicious account when flying the B-727 where both the Captain and the F/E remember him being quick to use massive rudder applications in an attempt to either maintain or, perhaps, from his perception, regain, control of the aircraft after having encountered wake turbulence. Determining why this particular incident was not followed might be an interesting effort – but perhaps the Captain and F/E believed the issue was isolated and had been properly addressed. I would wonder if any instructor or check airman ever noticed similar tendencies from this young man. It would be interesting to find out from the instructor who administered the AA Advanced Maneuver Training to this F/O if he demonstrated any tendency to “over control” the rudder during that training.

********************************************************

The exact testimony is here -

http://ntsb.gov/Events/2001/AA587/exhibits/240247.pdf

pages 36-44.

The F/E did not remember the incident that the Captain testified about. The Captain said he discussed it with the FO and it never happened again.

Don't take my word for it, read the testimony.

[Loose rivets]

Well, the first two answers (183 & 184 ) do seem logical and indeed conclusive, but I still wonder what the P1 was thinking when he posed the question “You alright?”.

We, all know that we can break an airliner with the elevators, the reaction in pitch is almost instantaneous, giving a very clear feedback via g-forces. However, the rudder is quite different and perhaps more subtle in the nature of such feedback, but it is still there--and a fundamental part of flying. I just can't understand these wild excursions of a control surface only bringing and almost rhetorical question from the P1.

I realize that the resultant tail-wagging could have been misidentified, just adding to the confusion, but surely, most competent PNFs, would have an awareness of the actual pedal movement. Perhaps it's ‘bad form' for a young co-pilot to hover over the captain's controls, but as a captain in these conditions, I know I would have had a tactile awareness of the pedals. Under the circumstances, it sounds as though it would have been difficult not to have. Perhaps by the time it was clear to the captain, it was too late.

It's as though a small paragraph has been omitted from the story: just something does not add up. But then, come to think of it, this is probably true for more than half the accidents that I have read about in the last 45 years.

[vapilot2004]

...... Did the A300 really have rudder inputs from the pedals like it showed in the video or did they just use rudder actuator inputs to the FDR to show what the rudder pedals would do to make the rudder move? ........... Does the Airbus really have rudder pedal movement in their FDR. Years ago I heard no.

There was an FAA mandate to install control input data sensors by August 2001. The CP data acquisition system was installed on this aircraft and was manufactured by a company in Florida.
This particular FDR records a digitised and filtered version of the control sensor data at a rate of only twice per second or 2hz. Data filtering is something the FAA/NTSB are moving to end as the practice can cause gaps in recorded data or miss extreme data points altogether and was apparent in this case.

A couple of points:
On examining the rudder pedal input data, the NTSB threw out American Airlines certificated correlation tables and proceeded to produce their own by a statistical averaging technique based on previous flight data. The newly created tables were then used to interpret the recorded rudder pedal data points.

Both in public hearings and the periodic updates, the NTSB chose only to reveal averaged amalgamations of the data with no reports available of the actual numbers recorded on the FDR.

In light of the data limitations and subsequent NTSB percolations, we should take the animations and graphs of flight control inputs with more than a few grains of salt.

[Rainboe]

I realize that the resultant tail-wagging could have been misidentified, just adding to the confusion, but surely, most competent PNFs, would have an awareness of the actual pedal movement. Perhaps it's ‘bad form' for a young co-pilot to hover over the captain's controls, but as a captain in these conditions, I know I would have had a tactile awareness of the pedals. Under the circumstances, it sounds as though it would have been difficult not to have. Perhaps by the time it was clear to the captain, it was too late.
They had a sudden, violent and totally unexpected wake encounter at an early stage. Not sure how flap retraction was going and the distraction of the After Take-off checklist. With the sudden buffeting, I think it is understandable the Captain was more pre-occupied with what was going on with the aeroplane and whether the co-pilot was coping- hence the query. I am sure no attention was given to the rudder pedal movement for those seconds, and indeed the violent movement of the rudder pedals (obscured behind the control column and his knees) was not noticed- any pilot had he seen that degree of movement would have queried it out of concern- and in the buffeting probably the motion induced by rudder overcontrol would be masked by the turbulence. I do not believe any pilot can identify yaw in different directions and apply full control and then reverse it at that rate, then repeatedly carry it all out again. Sadly, we do nobody any service by denying the obvious- the fin came off because of violent and sustained overcontrol. The way ahead is to ensure all pilots are thoroughly educated on limitations of the system, much as we have been educated on likely causes of 737 rudder hardovers and how to handle them.

[JustAnothrWindScreen]

I am sure no attention was given to the rudder pedal movement for those seconds, and indeed the violent movement of the rudder pedals (obscured behind the control column and his knees) was not noticed- any pilot had he seen that degree of movement would have queried it out of concern- and in the buffeting probably the motion induced by rudder overcontrol would be masked by the turbulence.

Correct me if I am wrong, but isn't full rudder travel at that speed in the A300 just about 1 inch of travel?

[Rainboe]

No- I would expect that would be at cruise speed at altitude. Without being familiar with the Airbus rudder system, I would expect at the lowish speed the Airbus was going- just after a turn, and within about 3-4 miles of JFK, a larger deflection of the pedals was required for the same rudder movement.

[DozyWannabe]

They had a sudden, violent and totally unexpected wake encounter at an early stage.
The pilots were expecting a significant wake encounter, and were cautioned to expect it by the tower - it could be argued that by the tone of voice on the CVR, the handling pilot wasn't too happy about how soon they were departing after the JAL 747. The rest of your points are bang on the money from this laymans point of view.

[JustAnothrWindScreen]

oops, previous post, and this post, from -


http://www.iasa.com.au/folders/Safety_Issues/RiskManagement/crowinstability.html
The Difference Between Certification Standards & The Real World

NTSB Member Debbie Hersman: If you are a line pilot, how likely would it be that you would get the full amount [of rudder]? Or get 1.2 inches of the pedal at 250 [knots airspeed]?
NTSB professional staff member David Ivey: If I were to put in rudder? And knowing what I had found that ... there was a very good chance you could put in full rudder [with 1.2 inches of travel]?[/I]

From an earlier post.

[Rainboe]

Thank you for that. I find it difficult to see that 1.2 inches travel would give full scale rudder deflection at low climb speeds. It would make engine out control difficult. The normal rudder system on the types I've flown reduces rudder response with speed, so at low take-off speeds, full rudder pedal movement gives full rudder deflection, but at high mach cruise speed, full rudder pedal movement (not that one would ever do it) will give vastly reduced rudder deflection. I recall the discussion earlier went into this, but could an A300 pilot say how the system works?

[DozyWannabe]

I recall the discussion earlier went into this, but could an A300 pilot say how the system works?

Not an A300 pilot, but I hope this helps...

http://www.ntsb.gov/events/2001/AA587/exhibits/241835.pdf

Contains a graph showing pedal travel limitation vs. IAS.

[Loose rivets]

Points taken Rainboe, and thinking about it, I spent so much of my time with new or inexperienced folk in the right seat, that I guess I find it hard to imagine not keeping token toes on the pedals, especially at critical times.


I do not believe any pilot can identify yaw in different directions and apply full control and then reverse it at that rate, then repeatedly carry it all out again.


I know that I'm beating the same drum, and perhaps alone in my thinking having become a dinosaur, but a tied gyro has been my closest friend in extreme turbulence. By extreme, I mean the horizon off the scale time and again, and 3,000 foot fluctuations in height. That little turn needle was all I had sometimes, and nothing, but nothing replaces it.

[Rainboe]

Never quite seen it that bad, though 30+ years ago, turbulence did seem worse, but maybe that was the way the VC10 punched its way through turbulence rather than the Boeing 'wallow'!
I think almost all pilots would let the aeroplane ride through a vortex encounter rather than slam the controls, especially rudder, to their limits. I can't believe the wake encounter was 'extreme'. Severe maybe, but this is an Airbus widebody following a heavy, and it could handle it. Throw into the mix a pilot with a habit of running controls to their stops to try and keep the aeroplane on the straight and narrow, and we have a ready-made disaster. I hope everybody has been educated since that sometimes it's better to let the disturbance take its course and gently correct afterwards rather than come out with all guns blazing to keep exactly on the bead. It must never happen again.

[JustAnothrWindScreen]

Thank you for that. I find it difficult to see that 1.2 inches travel would give full scale rudder deflection at low climb speeds. It would make engine out control difficult. The normal rudder system on the types I've flown reduces rudder response with speed, so at low take-off speeds, full rudder pedal movement gives full rudder deflection, but at high mach cruise speed, full rudder pedal movement (not that one would ever do it) will give vastly reduced rudder deflection.

I could not agree with you more Rainboe. I have flown most of the century series fighters and quite a few of the large airliners. They were all built and reacted just as you have described.

[RatherBeFlying]

As previously noted in this thread and the NTSB report, the maximum rudder pedal travel at the accident airspeed was 1.2 inches, the breakout force was 22 pounds and the maximum deflection force was 35 pounds.

The PF got full rudder -- whether that was what he wanted or expected from his inputs is another question.

[misd-agin]

The a/c was accelerating just prior to the incident. The acceleration was at a faster rate then the reduction effect of the rudder travel limiter, which resulted in the ability to displace the rudder slightly farther than expected.

Guys, if you're really interested in the accident read the NTSB report. It will be enlightening for many that havn't already been enlightened by the accident.

[john_tullamarine]

Having run through this thread to refresh my memory (and deleting a few things in the process), the following points are noted ..

(a) the topic is close to all our piloting hearts and, as a consequence, generates strong feelings

(b) aircraft are not designed to be "perfectly" safe and may be lost in unusual and extreme circumstances .. especially when we get in areas outside the routine design/certification and pilot experience/training paddocks

(c) as aircraft designs become increasingly complex, the piloting fraternity becomes progressively less knowledgeable on the details .. indeed, for many years, most training has been moving to a need to know, rather than nice to know, philosophy. This, combined with a generally low knowledge level regarding certification practices and requirements, can help set up situations as in (b)

(d) with very rare exceptions, it is reasonable to presume that the design, certification, and operational training systems (and pilots) are all trying their level best to do the "right" thing along the way.

That the occasional extreme event crops up is tragic but is also confirmation that the overall system is not too far from a reasonable position .. in that the accident rate from these sorts of events is extremely low.

Can I ask that posters reflect upon their posts prior to putting them in concrete .. the aim is to encourage a rational debate/discussion on the matter with a minimum of huff and puff angst.

The basic rule is "play the ball, not the man"

The moderators will cut a fair bit of slack .. but there comes a point where we must adjudicate.

[barit1]

Excellent overview, John.

I don't mean this to be flippant, but to summarize, every time the designers make the machine more Murphy-proof, the end result is a new-and-improved generation of Murphies. (I say this with some authority, having been on both side of this equation at various times.)

[john_tullamarine]

barit1 - and ain't that the truth of life in general .... ?

Two problems come to mind immediately -

(a) we all are subject (regardless of our walk of life) to developing expectations which are unrealistic .. in the case of aircraft that occurs when we confuse pretty good reliability and safety (which is what we have in general) with absolute versions (which don't exist). Like it or not, life (in general) and aircraft (in particular) are subject to statistics and probabilities. The aim of the game is to load the dice our way to the extent reasonably achieveable.

(b) ever present cost pressures put ever increasing pressures on the training world with the result that the younger flying folk perhaps don't have some of the useful skills in which the old codgers were drilled. Button pressing is an essential skill in the present flying world .. but it would be nice to think that the basics underpin the gloss.

Where is the optimum solution ? .. beats me.

For the aviation fraternity, PPRuNe provides for a sounding board environment along with an extremely useful background knowledge training tool. In the several technically biased forums there are some very, very well qualified and knowledgeable folk who give freely of their hard won experience to the benefit of the new folk.

[vapilot2004]

Having run through this thread to refresh my memory (and deleting a few things in the process), the following points are noted ..
(a) the topic is close to all our piloting hearts and, as a consequence, generates strong feelings
(b) aircraft are not designed to be "perfectly" safe and may be lost in unusual and extreme circumstances .. especially when we get in areas outside the routine design/certification and pilot experience/training paddocks
(c) as aircraft designs become increasingly complex, the piloting fraternity becomes progressively less knowledgeable on the details .. indeed, for many years, most training has been moving to a need to know, rather than nice to know, philosophy. This, combined with a generally low knowledge level regarding certification practices and requirements, can help set up situations as in (b)
(d) with very rare exceptions, it is reasonable to presume that the design, certification, and operational training systems (and pilots) are all trying their level best to do the "right" thing along the way.
That the occasional extreme event crops up is tragic but is also confirmation that the overall system is not too far from a reasonable position .. in that the accident rate from these sorts of events is extremely low.
Can I ask that posters reflect upon their posts prior to putting them in concrete .. the aim is to encourage a rational debate/discussion on the matter with a minimum of huff and puff angst.
The basic rule is "play the ball, not the man"
The moderators will cut a fair bit of slack .. but there comes a point where we must adjudicate.

Would some good soul p l e a s e buy this good man a drink (or five) - and kindly send me the bill - by all means. :}


Master JT's post should be inscribed on a (bronze?) plaque and displayed upon the walls of all who inhabit these forums - particularly the X vs Y discussion participants. :ok:

[Few Cloudy]

As we are now on the tech site - carbon has a different ageing characteristic from that of metals, which actually start to age (in a more or less predictable way) from day one. Carbon stays "as good as new" until its breaking point is reached, when it just goes all at once.
The trick is to design a high enough breaking point. To illustrate this in everyday life, racing bike frames of carbon last much longer than aluminium ones - but if you crash one it won´t bend - it will snap.
On the matter of technique, it might be appropriate to recall John Farley´s words from another thread:
I am concerned that several pilots seem genuinely baffled that rudder use could have the fin off a fully serviceable aircraft that was properly designed and certificated. Unhappily it can, as I will try to explain in a moment.
Before I go on please may I emphasise I am not suggesting this caused the accident this thread is about, but offer these comments to the general debate about rudder use that is going on.
The mechanism I refer to is the same one employed by adults when helping youngsters to enjoy a swing. The adult applies a very small force at just the right moment in the cycle and by so doing builds up the oscillation until in the end the displacement of the swing can become very large indeed (with much yelping from the occupant)
A similar relatively small side force generated by rudder deflection, repeatedly applied, can cause a yaw oscillation to build rather than damp. There are two possible end points in this case, either the fin will stall due to the size of its AoA (in which case the aircraft will depart from controlled flight) or the fin will break before it stalls due to aerodynamic overload.
We all enjoy the powerful damping effects of yaw autostabilisers when they produce a very small force and apply it at the right moment to reduce the yaw oscillations. Now imagine a yaw autostabiliser that is working in reverse. Or a pilot that is out of phase with his feet. Or a pilot that is pushing the rudder pedals correctly but control actuation lags result in those correct inputs being delayed to an incorrect time.
Quote from John Farley,
Post from FC.

[AirRabbit]

The F/E did not remember the incident that the Captain testified about. The Captain said he discussed it with the FO and it never happened again.
Don't take my word for it, read the testimony.
While I don't have any additonal comments on this particular subject, I DID want to acknowledge the link and the reference to the Flight Engineer's comments you provided. My information was obviously bogus and you are, indeed, correct. I stand corrected about what I thought were the F/E comments.

[Rainboe]

Having just watched the documentary on Sky about the accident, the AA pilot replicating the event in the simulator was applying not 1.2" rudder, but a good 6 inches or so, which is what I would expect at low speed. Who threw in this blinder about 1.2"? It is incorrect! Large inputs of rudder were made. It would appear almost full scale deflection, not 1.2" movement. To have another AA pilot testifying that it was not known that you should not use rudder under such circumstances I found slightly bizarre, and unconvincing.

[RatherBeFlying]

Who threw in this blinder about 1.2"? It is incorrect! Large inputs of rudder were made. It would appear almost full scale deflection, not 1.2" movement.
The AA587 NTSB report is available at: http://www.ntsb.gov/publictn/2004/AAR0404.pdf
The 1.2" of rudder pedal travel appears on page "27" (41 of the document) in: Table 4. A300-600 Rudder Control System Design Characteristics Compared With Those of Other Airplanes
A300-600 22.0 65.0 4.0 30.0 32.0 1.2 9.3The columns are:

Airplane
Breakout force
135kt. Pedal force
135kt. Pedal travel
135kt. Rudder deflection

250kt. Pedal force
250kt. Pedal travel
250kt. Rudder deflection

[Rainboe]

Well the guy doing the simulator replication used large amounts, not 1.2". I'm inclined to believe what the simulator did, not what the FAA report stated, as all jets I know of work pretty similar. I do not believe the A300 uses 1.2" rudder pedal deflection to produce large rudder response at low climb speed. If the report insinuates this, it is written wrongly. That AA pilot on film was using large foot movements. Small or large anyway, there is no argument- the fin came off through overstressing because of large rudder deflections, not through any defect and not because it collected water. The only productive discussion is why was this technique used and are the implications of it understood by those who professed at the time to not understand the hazards involved. If anybody is still in doubt about the point, they should stop passenger flying forthwith until they are trained up.

[AirRabbit]

Well the guy doing the simulator replication used large amounts, not 1.2". I'm inclined to believe what the simulator did, not what the FAA report stated, as all jets I know of work pretty similar. I do not believe the A300 uses 1.2" rudder pedal deflection to produce large rudder response at low climb speed. If the report insinuates this, it is written wrongly. That AA pilot on film was using large foot movements. Small or large anyway, there is no argument- the fin came off through overstressing because of large rudder deflections, not through any defect and not because it collected water. The only productive discussion is why was this technique used and are the implications of it understood by those who professed at the time to not understand the hazards involved. If anybody is still in doubt about the point, they should stop passenger flying forthwith until they are trained up.
Well first, it wasn't an "FAA report," it was an NTSB report - second, the simulator is going to do whatever it is programmed to do - nothing more ... nothing less. With proper programming you can make any simulator fly just like the space shuttle. And as you should know, the FAA evaluates simulators to make sure they perform and handle as much like the airplane as can be determined. The data they use for comparison purposes is data gathered during flight testing of the airplane. If you were watching someone in the simulator flailing around on the rudder and the pedal deflections were more than the 1.2 inches described, then I can promise you the airspeed was significantly less than 250 knots and I can promise you that the deflection was more on the order of 4 inches than it was 6 inches. (Sometimes pilots have a problem discerning the difference between those measurements, but that's a debate for another forum!)

No one has said that "the A300 uses 1.2 inches of rudder pedal deflection to produce large rudder response at low climb speed." The accident report specifically describes maximum rudder pedal deflection at 135 KCAS (note-calibrated airspeed) as being 4 inches using 65 pounds of force, and at that maximum pedal deflection, the rudder should be deflected 30 degrees. The same chart (and I'm referring to the chart on page 23 of the report - but, the chart on page 27, cited by RatherbeFlying, is quite eye popping in the relationships it shows!) describes maximum rudder pedal deflection at 250 KCAS as being 1.2 inches using 32 pounds of force (there is a note, stating that this 1.2 inches may change slightly because of the response of the yaw damper), and at that maximum rudder pedal deflection, the rudder should be deflected 9.3 degrees.

So the comparison between the A300-600 and the B-767 (similar sized airplanes) goes like this (same info as supplied by RatherbeFlying, but perhaps a little easier to read:

At 135 knots:

A300-600
breakout force = 22.0 pounds
pedal force at maximum deflection = 65 pounds
pedal travel at maximum deflection = 4.0 inches
rudder deflection at this point = 30.0 degrees

B-767
breakout force = 17.0 pounds
pedal force at maximum deflection = 80 pounds
pedal travel at maximum deflection = 3.6 inches
rudder deflection at this point = 26.0 degrees

At 250 knots

A300-600
pedal force at maximum deflection = 32 pounds
pedal travel at maximum deflection = 1.2 inches
rudder deflection at this point = 9.3 degrees

B-767
pedal force at maximum deflection = 80 pounds
pedal travel at maximum deflection = 3.6 inches
rudder deflection at this point = 8.0 degrees

[RatherBeFlying]

I have not seen any research that contradicts the NTSB investigation factual findings in the report.

Certainly Airbus Industrie would have raised objections had this (or any other) number been in error.

[airsupport]

I have not seen any research that contradicts the NTSB investigation factual findings in the report.
Certainly Airbus Industrie would have raised objections had this (or any other) number been in error.

Airbus will of course not object to any of the findings, unless they are blamed.

Then they would object big time.

[DozyWannabe]

That's why accident reports as a rule are findings of fact rather than attempts to apportion blame. While you do get the occasional incident where gross negligence on the part of a single party becomes the primary cause, those are few and far between.

As it happens, this case was not one of those. To imply this was a case of corporate and political collusion to blame a pilot, as quite a few on here have, is disingenuous in the extreme. The pilot's actions were down to his interpretation of the training he had been through, the aircraft did not behave as he expected, and he ended up in a dangerous situation probably before he even realised it.

Those were the findings in a nutshell - no blame, no insinuation of negligence or incompetence, just holes in the cheese lining up with tragic results.

[RatherBeFlying]

There has been a large volume of discussion about the various particular holes in the cheese in this accident.

In the case of this particular hole, had the PF managed to apply 27 pounds to move the rudder 0.6 inches instead of the 32+ pounds to move it 1.2 inches, the triggering event may not have happened.

Part of this particular hole was that there was no broadly shared knowledge at the time of the rudder characteristics at 250 kt. so that once the PF applied rudder he was likely surprised by the response.

I suspect that he tried to correct getting a bunch more rudder than he expected, but was unable to modulate or recognise he had fallen into APC/PIO.

An inch.2 of movement followed by an inch.2 back over a couple cycles ... and the fin and rudder were gone.

[aardvark2zz]

Good stuff.
.
Also, note that the rudder mechanism does have the proper speed of the plane. The speed is approx 30 kts less while accelerating.
.
Therefore as the plane was going 250 kts the internal rudder-mechanism speed signal was 220kts due to time filtering.
.
And therefore more deflection was possible than designed for. See reports and slides.
.

Well first, it wasn't an "FAA report," it was an NTSB report - second, the simulator is going to do whatever it is programmed to do - nothing more ... nothing less. With proper programming you can make any simulator fly just like the space shuttle. And as you should know, the FAA evaluates simulators to make sure they perform and handle as much like the airplane as can be determined. The data they use for comparison purposes is data gathered during flight testing of the airplane. If you were watching someone in the simulator flailing around on the rudder and the pedal deflections were more than the 1.2 inches described, then I can promise you the airspeed was significantly less than 250 knots and I can promise you that the deflection was more on the order of 4 inches than it was 6 inches. (Sometimes pilots have a problem discerning the difference between those measurements, but that's a debate for another forum!)
No one has said that "the A300 uses 1.2 inches of rudder pedal deflection to produce large rudder response at low climb speed." The accident report specifically describes maximum rudder pedal deflection at 135 KCAS (note-calibrated airspeed) as being 4 inches using 65 pounds of force, and at that maximum pedal deflection, the rudder should be deflected 30 degrees. The same chart (and I'm referring to the chart on page 23 of the report - but, the chart on page 27, cited by RatherbeFlying, is quite eye popping in the relationships it shows!) describes maximum rudder pedal deflection at 250 KCAS as being 1.2 inches using 32 pounds of force (there is a note, stating that this 1.2 inches may change slightly because of the response of the yaw damper), and at that maximum rudder pedal deflection, the rudder should be deflected 9.3 degrees.
So the comparison between the A300-600 and the B-767 (similar sized airplanes) goes like this (same info as supplied by RatherbeFlying, but perhaps a little easier to read:
At 135 knots:
A300-600
breakout force = 22.0 pounds
pedal force at maximum deflection = 65 pounds
pedal travel at maximum deflection = 4.0 inches
rudder deflection at this point = 30.0 degrees
B-767
breakout force = 17.0 pounds
pedal force at maximum deflection = 80 pounds
pedal travel at maximum deflection = 3.6 inches
rudder deflection at this point = 26.0 degrees
At 250 knots
A300-600
pedal force at maximum deflection = 32 pounds
pedal travel at maximum deflection = 1.2 inches
rudder deflection at this point = 9.3 degrees
B-767
pedal force at maximum deflection = 80 pounds
pedal travel at maximum deflection = 3.6 inches
rudder deflection at this point = 8.0 degrees

[AirRabbit]

There has been a large volume of discussion about the various particular holes in the cheese in this accident.
In the case of this particular hole, had the PF managed to apply 27 pounds to move the rudder 0.6 inches instead of the 32+ pounds to move it 1.2 inches, the triggering event may not have happened.

Perhaps this is true. But, the question remains ... why was it this pilot thought it necessary to use the rudder to counter any rolling tendency upon encountering wake turbulence in the first place? That's not what the AA Advanced Maneuver Training teaches; in fact, I'm not aware of any teaching anywhere that advocates the use of rudder to control roll - in either high or low speed portions of the envelope.

[airsupport]

So many different theories.

The real cause will be discussed at length at the picnic. ;)

[misd-agin]

Well the guy doing the simulator replication used large amounts, not 1.2". I'm inclined to believe what the simulator did, not what the FAA report stated, as all jets I know of work pretty similar. I do not believe the A300 uses 1.2" rudder pedal deflection to produce large rudder response at low climb speed. If the report insinuates this, it is written wrongly. That AA pilot on film was using large foot movements. Small or large anyway, there is no argument- the fin came off through overstressing because of large rudder deflections, not through any defect and not because it collected water. The only productive discussion is why was this technique used and are the implications of it understood by those who professed at the time to not understand the hazards involved. If anybody is still in doubt about the point, they should stop passenger flying forthwith until they are trained up.


Believe a simulator "replication" as opposed to the factual report of the NTSB? :confused:

You're inclined to believe the simulator because all jets you know of work similar? Hmmm, I think that's the first time I've seen the simulator being more accurate than the aircraft it's trying to simulate. :sad:

You said all the jets you know work pretty similar. I think your profile showed 747 and 737 knowledge. If you're talking about the rudder limiting systems, which is an issue in this crash, then they are not similar. The 747 rudder gives you about 80% more rudder travel per pound of rudder travel vs. the 737. 747 vs. A300-600R? Only 21% as sensitive. 737 vs A300-600R? Only 12% as sensitive.

You do not believe the Airbus uses 1.2" of rudder travel at low speed? Well you're either correct or very wrong. Are you talking about "low speed" or are you talking about the accident? Two distinctly different scenarios.

If you see noticeably leg movement the a/c is probably below 165 kts, or close to it.

In summary, the simulator replication showed leg movement :ugh: , the facts don't matter, the FDR is wrong, the a/c rudder limiter doens't work like the engineers said it does:ooh: , and all rudder designs you know "work pretty similar". :=

:{:{ :{

[Mad (Flt) Scientist]

To add to the above. On at least some of our (non-Airbus) designs which incorporate rudder travel limiters, the mechanics of travel limiting are similar to the Airbus system (i.e. fixed pedal/rudder gain) as opposed to the Boeing (variable gain) system and pedal travel of the order of 1/4 full travel at 250kts is entirely plausible.

If you consider that you'll want full travel at low speed (say 125 kts) and assume that your travel limits are simplistically set for a constant rudder*Q, then at 250kts you'd have 1/4 travel, and at 375kts you'd have 1/9 travel.

I certainly wouldn't place anecdotal and qualitative simulator evidence ahead of properly analysed engineering test data.

[misd-agin]

Perhaps this is true. But, the question remains ... why was it this pilot thought it necessary to use the rudder to counter any rolling tendency upon encountering wake turbulence in the first place? That's not what the AA Advanced Maneuver Training teaches; in fact, I'm not aware of any teaching anywhere that advocates the use of rudder to control roll - in either high or low speed portions of the envelope.

Some military fighters use rudder at high AOA manuevering for roll. I'm not sure about the new 'computer' generation but it was the way to get roll at slow speed/high AOA.

Obviously with a HUGE degree of heightened awareness and feel!
Figher pilots talk about 'stalls' and 'departures'. They ain't the same....:eek:

[ftrplt]

actually, modern fighter pilots dont talk about stall; they talk about 'rate of falling out of sky'.

Fighters only use rudder for roll at very high AOA's; not really applicable to this situation.

[Rainboe]

This aeroplane was climbing out over Jamaica Bay within about 5 miles of JFK at the encounter. I would think they were going slower than 250kts! Whatever the distance of rudder travel, I am still bemused that any experienced pilot would use rudder as primary control in that circumstance, and how he assessed it. The fatal flaw was human technique and presumably training, not fin attachment. The A300 has been carrying the can quite unfairly.

[airsupport]

The fatal flaw was human technique and presumably training, not fin attachment. The A300 has been carrying the can quite unfairly.

In your opinion, not everyones.

If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.

However IF you are aware of these problems with the A300 composite tail, a design Airbus no longer use, makes much more sense.

[Mad (Flt) Scientist]

If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.

You just grounded every single aircraft flying

Once again, severe enough pilot inputs will cause catastrophic damage to every aircraft out there. There's no doubt about that; the only variable is the degree of severity required, but push them hard enough and they all will break.

*caveat: except POSSIBLY FBW-envelope protected types *cough*Airbus*cough* - but even those may not be fully immune. We don't design aircraft to be flown in a carefree manner, generally, and never in a careless manner.

[Rainboe]

airsupport,
If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.
Well the exact cause of several 737 rudder hardover crashes was never precisely pinned down, so why are 737s flying today? Because we know the problem, we've been trained how to handle it and it is a known risk. So are you saying that we don't know the fin problem? Since my basic training, I was told in no uncertain terms to leave the rudder alone- it's for engine failure, spin recovery, aerobatics. If I ever tried to cheat on approach and slip a little rudder in to line up, I got very short treatment. If I touched the rudder on approach on large jets, I had rude comments made. I think the whole of British aviation is aware you don't mess about with rudder. So how does the public feel watching an AA Captain at the accident hearing answering earnestly "no Sir, we didn't know you couldn't apply rudder like that!" There comes a time when trying to protect one man's reputation becomes counter-productive to safety. I suggest the lesson is drilled home without doubt- no professional pilot should be flying unaware that the fin is not designed for this, and certainly not stressed for it, on any other jet either.

[bubbers44]

Can I watch your first landing in a taildragger like a Twin Beach landing in a crab?

[barit1]

Some folks have Multi-engine licenses "Restricted to centerline thrust only".

For a few decades I've advocated licenses "restricted to tricycle undercarriage" until tailwheel competency is demonstrated. :ugh:

[airsupport]

Rainboe,
There you go, twisting my words AGAIN. :ugh:
I said If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.
The B737 incidents you are on about IF TRUE, were with an UNSERVICABLE Airliner/s.
Just as was the case I still feel with the AA A300 out of JFK.
I still honestly think that if any serviceable Airliner (that is no faulty components or weakened structure) can be brought down PURELY by mechanically allowable (whether normal or not) Pilot inputs then it should NOT be flying.

[Rainboe]

I'm not twisting your words, but I do not believe any Boeing fin could take the strain this fin was put under either If I recall correctly, the photographs of the breakages that occurred showed the metal lugs parted company at the attachments- I'm not sure how much the carbon fibre fin was actually involved in the separation.
I have flown DHC Chipmunk and Auster tailwheels. That class of aeroplane has a much tougher structure with the fin integral with the fuselage structure. Perch a fin on top of the fuselage and attached at the base by lugs, and you have a modern airliner construction that won't take abuse, especially at faster speeds.

[DozyWannabe]

I still honestly think that if any serviceable Airliner (that is no faulty components or weakened structure) can be brought down PURELY by mechanically allowable (whether normal or not) Pilot inputs then it should NOT be flying.

I repeat Mad (Flt) Scientists reply from earlier, which you've apparently missed - or maybe you're wilfully ignoring:

You just grounded every single aircraft flying

Once again, severe enough pilot inputs will cause catastrophic damage to every aircraft out there. There's no doubt about that; the only variable is the degree of severity required, but push them hard enough and they all will break.

*caveat: except POSSIBLY FBW-envelope protected types *cough*Airbus*cough* - but even those may not be fully immune. We don't design aircraft to be flown in a carefree manner, generally, and never in a careless manner.
I'd be tempted to be more specific and say that you'd be grounding every airliner out there, but his point still stands. Have a look at the first few pages of this article:

http://www.flyingmag.com/article.asp?section_id=12&article_id=527

Va (AKA Manouevering Speed) has been a fact of life for pilots for decades - although it was primarily concerned with structural integrity involving wings and horizontal stabilisers, the vertical stab was apparently not originally considered in these calculations.

The simple fact is that your criteria, i.e. being able to rip the vertical stabiliser off through pilot action alone - are applicable to pretty much every large transport-category aircraft currently flying, be they Boeing, Airbus, Tupolev... whatever.

[Mad (Flt) Scientist]

I'd be tempted to be more specific and say that you'd be grounding every airliner out there,

Yes, my apologies, I carelessly used "aircraft"; obviously there are some aircraft that may be exceptions.

[airsupport]

I repeat Mad (Flt) Scientists reply from earlier, which you've apparently missed - or maybe you're wilfully ignoring:
I'd be tempted to be more specific and say that you'd be grounding every airliner out there, but his point still stands. Have a look at the first few pages of this article:
http://www.flyingmag.com/article.asp?section_id=12&article_id=527
Va (AKA Manouevering Speed) has been a fact of life for pilots for decades - although it was primarily concerned with structural integrity involving wings and horizontal stabilisers, the vertical stab was apparently not originally considered in these calculations.
The simple fact is that your criteria, i.e. being able to rip the vertical stabiliser off through pilot action alone - are applicable to pretty much every large transport-category aircraft currently flying, be they Boeing, Airbus, Tupolev... whatever.

Yes I ignored it, I was hoping to keep the discussions logical.

IF (which I hope is NOT true) there are ANY Commercial Airliners out there now, where failure of primary structure and loss of the hull with all the souls on board, can be caused by ONLY (mechanically or electronically) allowable movements of Pilot controls, without any defects on the Aircraft, then they should be grounded IMMEDIATELY.

The scenario is just too ridiculous to to be true, hopefully.

Can you imagine the outcry if this was true say with a car, that on a particular make and model of car, in perfect working order, simply moving one of the pedals "too far or hard" would cause loss of the car and all the lives on board?

That car would quite rightly be removed from the roads immediately, just as these Airliners (IF what you say is true) should be removed from the skies IMMEDIATELY.

[Mad (Flt) Scientist]

It was ALREADY widely known, even before this accident, that full application of controls at speeds above Va - so called "manoeuvring speed" - could cause structural failure.

All that happened here was the exposure to the fact that aggressive control input, even below Va, can cause catastrophic effects.

To take your motoring analogy - any car will spin if handled badly in a corner. Many high vehicles will topple similarly. Full throttle will, if applied long enough, overspeed the tyres above their rated speeds. gear changes from top to first, or reverse, will destroy the engine. Sudden braking may cause skids and loss of control.

And we haven't started yet on the ability to drive into walls, other vehicles, etc.

All machinery must be operated with, and treated with, respect. Airline pilots require training and licensing to qualify them to operate the complex, and dangerous, machines they fly. If the machines were foolproof, the airlines could save a lot of training bills by simply hiring fools.

[airsupport]

I give up. :ugh:

It is a waste of time expecting sensible debate here, I will save it for the picnic. ;)

[Rainboe]

One gets a similar feeling to know there appears to be a large group of pilots, apparently uniquely American, and from one particular large airline with an eagle on a silver tail, who are professing complete ignorance to any limitation on being able to mistreat aeroplane controls without having structural failure 'as long as you are below Va'. Large airliners are not F16s, and treating an airliner rudder as if you are flying a Pitts Special with multiple rapid reversals is just not on. What is more frightening is there appears to be an airline full of pilots who can only point to 'design defect' and not recognise the real cause. Your picnic, whatever it is, needs to be a comprehensive breakdown of how to handle unusual attitudes and recommended techniques on the controls.

[Shore Guy]

Gentlemen and Ladies (not so much in order of preference or political correctness, but order of “who does it”),


I am not familiar with the basic and advanced training concepts in areas other than North America, but……

I would wager a months pay that pilots on the west side of the Atlantic, at a ration of 9 to 1 or greater, would have, prior to AA 587, said that if all systems were operating normally (specifically rudder limiter), that “stop to stop” would be within Part 25 certification limits and would NOT have resulted in catastrophic airframe damage. I was wrong…..We were wrong.

After the accident, and after research, it became apparent that even NACA documents from the twenties showed this was not true. But we were not educated or trained of such, in fact, for many of us, the opposite. There is reference on the web still today that –

” VA
design maneuvering speed (stalling speed at the maximum legal G-force, and hence the maximum speed at which abrupt, full deflection, control inputs will not cause the aircraft to exceed its G-force limit). Maneuvering speed is limited by aircraft structural characteristics.

1-18-07



Not true, as a result of the investigation into AA 587.


Perhaps the pilot/pilots involved were “rough” with the airframe. But with existing knowledge, no one would have thought they would compromise the airframe, resulting in a catastrophic failure.

Yes, the Advanced Manueveing Course may have been a contributor. So may have the “Rube Golberg” Rudder Limeter system incorporated in the A-300 series (what were they thinking?).

Unfortunatly in this business, wreckage and bodies are the major empasis for education. Sad but true.

“There but for the grace of God……..”

[Rainboe]

Just as a reminder, control useage can be viewed here:
http://www.alexisparkinn.com/photogallery/Videos/2006-9-5_Flight-587-Rudder-accident-animation.wmv

Whilst I can appreciate there may be some adverse opinion of the design, there is also equal adverse opinion of piloting technique in this incident.

[Clandestino]

*caveat: except POSSIBLY FBW-envelope protected types *cough*Airbus*cough* - but even those may not be fully immune.

A320s envelope protection through FBW does not extend to yaw/sideslip. And that´s because, once again, rudder is not primary control on any transport category aircraft and shouldn´t be used as such. (not pointed at you Mad(flt)Sceintist, i got your point, just for the ones who might say that Airbus should protect their airplanes in yaw too). Of course you can and will use it to roll the plane but only after all of your ailerons and roll spoilers are rendered inoperative and that´s fairly unlikely event. Rolling with rudder while your roll control channel is operative will most likely lead to PIO (or APC if you´re newspeak´s fan) and PIO leads to... AA587. Just take a look at NTSB animation of cockpit control movements.

Despite JT´s warning to play the ball and not the man, I really, but really have the urge to comment on some posters here. I think it was mid 2002 when we got the letter from mr Caldarelli of ATR, not to use rudder for roll control and warning we might shed a tail if we don´t obey. Soon after that, the yellow FCOM pages arrived and by winter they were replaced by white pages, conveying the same message. Recently I´ve exchanged ATR FCOM for A320´s and there was the message again: don´t roll airplane with rudder and don´t cycle rudder, because when oscillations start, flying below Va does not offer protection. I think that every FCOM (AFM, POH. OM-B...) of the transport category airplane in the world has the same warning nowadays, as a result of AA587 accident. So people who are unable to grasp the significance of the warning, either don´t have the FCOM, or worse, have the FCOM but don´t bother to read it. I hope that no one here falls within bounds of second cathegory.

[Mad (Flt) Scientist]

I give up. :ugh:
It is a waste of time expecting sensible debate here, I will save it for the picnic. ;)
What kind of nonsensible contribution do you find in my statements?
It is a matter of simple engineering fact that aircraft are not designed - and not REQUIRED to be designed - to be immune to the consequences of any conceivable pilot input. I'll add to the last post by clandestino that every single one of our types has a similarly worded AFM/FCOM warning about the consequences of excessive control use.

You appear to be expecting 100% guarantees in your aircraft design; it doesn't exist in either structures or systems, and isn't required.

[airsupport]

What kind of nonsensible contribution do you find in my statements?
It is a matter of simple engineering fact that aircraft are not designed - and not REQUIRED to be designed - to be immune to the consequences of any conceivable pilot input. I'll add to the last post by clandestino that every single one of our types has a similarly worded AFM/FCOM warning about the consequences of excessive control use.
You appear to be expecting 100% guarantees in your aircraft design; it doesn't exist in either structures or systems, and isn't required.

Well that explains your position on this, by "every single one of our types", I take you work for Airbus?

You admit here that your aircraft are not designed to withstand all the stresses that may occur during flight, yet still it is not your fault, you blame the dead Pilot. :(

[Tree]

A point of interest:

The 737 rudder hard-overs did not cause the fin to separate.

[Mad (Flt) Scientist]

Well that explains your position on this, by "every single one of our types", I take you work for Airbus?
You admit here that your aircraft are not designed to withstand all the stresses that may occur during flight, yet still it is not your fault, you blame the dead Pilot. :(

Actually, no I do not work for Airbus, and never have. I have no reason to be biased towards them, or to blame anyone. I find it interesting that you assume that I must be coming from a position of inherent bias.

Once again, because you seem determined to ignore this point:
This could have happened similarly to any airliner in service today.

No-one - not Airbus, not Boeing, not Embraer, not Bombardier, no-one - designs their aircraft to sustain any conceivable control inputs. It's not an "admission", it's a simple statement of fact. Furthermore, the regulations to which all those aircraft are certified don't REQUIRE any conceivable control inputs to be considered; there are very specific cases defined, and if you do something more extreme than those cases, you are in unknown, and potentially VERY dangerous territory.

And if you read the NTSB report you'll see that they don't "blame the dead pilot" -at least not solely. As always, any accident has a number of causes, and the manner in which the aircraft was flown was but one part of the puzzle. There do seem to be some specifics of the flight control design which renders this design more vulnerable to such an event.

[Mad (Flt) Scientist]

A point of interest:
The 737 rudder hard-overs did not cause the fin to separate.

The regulations for rudder load manoeuvres DO require that you be able to sustain a single full authority control application, so it's not surprising that the 737's didn't suffer fin failures in that event.

Oscillatory/reversing rudder inputs are outside the regulatory requirements, aircraft are not designed to withstand them, and that is unfortunately what happened in this accident.

[Mad (Flt) Scientist]

Finally, can I draw your attentions towards the recommendations section of the NTSB report:

Develop and disseminate guidance to transport-category pilots that
emphasizes that multiple full deflection, alternating flight control inputs
should not be necessary to control a transport-category airplane and that
such inputs might be indicative of an adverse aircraft-pilot coupling event
and thus should be avoided. (A-04-59)

Amend all relevant regulatory and advisory materials to clarify that
operating at or below maneuvering speed does not provide structural
protection against multiple full control inputs in one axis or full control
inputs in more than one axis at the same time. (A-04-60)

Taken together, these recommendations are the reason we have cauitionary notes in our AFMs, and why I believe EVERYBODY has such notes - we were basically ordered to put them in following the accident. Because they apply to everyone.

[airsupport]

More proof, not than any more was needed, that books and manuals were changed AFTER this terrible event, to cover weaknesses in the Aircraft.

Effectively these Aircraft are continuing to operate under a de facto MEL, fit to continue flying as long as control inputs are manually limited.

[Mad (Flt) Scientist]

The weakness is in the regulations, not the aircraft. Airliners are not designed for these kinds of manoeuvres.

I believe the NTSB report says the fin failed at twice design load; the actual max may have been higher, but let's assume that the regs get changed to effectively double the design loads requirements. To be consistent, you'd have to follow a "carefree inputs" philosophy in all axes, so let's double ALL the manouvre loads.

Now, manoeuvre loads don't always design the structure, but if they did, doubling the load will generally require twice the thickness or strength. We just, in effect, doubled the structural mass of our design, at least for primary structure.

So we've grounded every existing airliner - because no amount of beefing up will double the design loads - AND ensured we can never design an economically practical one to replace them, because they'll be far too heavy.

As to your last comment; that the plane be operated according to the procedures in the manuals is the only assumption one can make. Every single limitation, caution, warning and procedure in the AFM is a reliance upon the trained people in the pointy end operating, literally, 'by the book'. if you don't then all kinds of nasty things happen.

Suppose you have an engine failure. What prevents you applying full rudder in the wrong sense, causing the aircraft to enter uncontrolled flight? Nothing except training and airmanship. if we restricted the rudder so that you couldn't apply it "the wrong way" we'd end up making the input automatic - the only way to prevent pilot control inputs from potentially catastrophic consequences is to prevent pilot control inputs - PERIOD. FBW envelope protection or full automation. As long as the man is in the loop, and in control, he has the ability to cause a tragic result. It's inevitable.

[airsupport]

This is getting worse.

This terrible tragedy occured to an Aircraft type that was the first to use this kind of technology, and as we know this particular type for various reasons was not maintained as well as it should/could have been, although these maintenance problems have now been corrected, and there are now no types manufactured the same as this one was.

Despite this, you initially jumped on the bandwagon of let's all blame the dead Pilot.

Now you are saying let's blame the Regulators.

What next?

Surely not where the blame really belongs............

[Rainboe]

You have to be joking! What you said cannot be serious. A wake vortex encounter is not an unusual event They happen. This type operated in Australia for years quite happily, having wake encounters. The fin came off because of the unusual pilot reaction to it. I would call it bizarre flying practices because I cannot believe the rudder reaction, the scale of the movements, and the rapidity. I'm quite sure even a 747 fin would come off if you did this to it. The fact that regulatory authorities are satisfied that the aeroplane as it stands is fit to continue operating with pilot 're-education' suggests that the cause is known.

[john_tullamarine]

Airsupport .. I don't know your background but it appears not to be related to any certification areas.

MFS (who is an aircraft designer chappie) has put the story pretty succintly in my view .. the general idea is that the OEM designs an aircraft to do a job and uses Industry standard techniques (with the occasional push to new technology) to design his bird. Along the way the internal system checks that the design standards (FAR25 and the like) can be satisfied.

Sometimes the OEM will endeavour to design more from the standards than from general practice and that can produce interesting results including both good and bad but, at the end of the day, it is a mix of those who know how to design, designing, with a view to getting the requisite tick in the box from the certification world so that the bird can be sold in the marketplace.

The reality is that the world is competitive .. therefore Brand A doesn't unilaterally make Brand A's product incredibly stronger than Brand B's .. as MFS has indicated .. the result is a steel girder bridge with no commercial value.

The pilot is required to be trained and licensed ... the operating techniques adopted by operator and pilot should be in accordance with the techniques recommended/required by the OEM/Type Certification.

Simply wishing that a transport category aircraft can be treated like an aerobatic machine remains just that .. wishful thinking .. the two animals are very different and the required operating techniques, likewise, are quite different.

It is not a case of the OEM having to second guess everything an enterprising operator or pilot might do ... rather, the OEM states what should be done ... the operator or pilot who wants to do something different without OEM blessing is out on his own.

.. and, then again, every now and again, technological status is challenged for the imperfect animal it is ... as, for instance, with Comet, etc.

Each of us in the game has his/her role to play .. it is a team effort ... except in those rare cases of gross incompetence or wilfully negligent behaviour it is not a case of assigning blame within the confines of the Industry (although the legal system may well do independently and in parallel).

[airsupport]

You have to be joking! What you said cannot be serious. A wake vortex encounter is not an unusual event They happen. This type operated in Australia for years quite happily, having wake encounters. The fin came off because of the unusual pilot reaction to it. I would call it bizarre flying practices because I cannot believe the rudder reaction, the scale of the movements, and the rapidity. I'm quite sure even a 747 fin would come off if you did this to it. The fact that regulatory authorities are satisfied that the aeroplane as it stands is fit to continue operating with pilot 're-education' suggests that the cause is known.

There you go twisting things again.

I didn't say anything about wake turbulence.

This type did operate in Australia, for a little over 12 months (not years), and yes we did not have this trouble (obviously as this was thankfully a one off), in fact we had very little trouble at all with them, and I had the pleasure of certifying for them for all that time, but they were NOT operating in the same environment as the AA one.

Later when with an identical Aircraft based in NY, and operating identical routes to the AA Aircraft, was when we had all the maintenance problems with the composite tail, not in Australia.

I do not know about the possibility of a tail coming off a B747, B737 or any other Airbus, and would never comment on such, however no matter how much you all ridicule me, I do KNOW that with an identical Aircraft (A300-600), operating out of the same Airport (JFK) and operating the same routes (down through the Caribbean), we had lots of maintenance problems with the tail, and I honestly feel this is a hell of a coincidence IF as you all say, this could not have possibly played a part in it.

However, I bow to your superior knowledge, even though you weren't there as I was, and will comment no more.

Save it for the picnic.

[AirRabbit]

Hey MFS – Thanks for keeping on keeping on. I gave up. Your voice and that of a few others, has been one of reason, professionalism, and expertise. I very much appreciate not only your comments, but the manner in which you provide them.
I don’t believe anyone here has ever “jumped on the bandwagon to blame the dead pilot.” The unfortunate fact is that the PF was the pilot flying, and, as such, has to bear at least some of the burden. Was there inadequate information available on the airplane? Probably. Inadequate regulations? Maybe. There certainly was inadequate understanding of what the regulations said. Inadequate training? An interesting question, given what was known, what was thought to be known, and what was not considered about the rules, and considering how those rules play out in an airplane with the kinds of controller deflection amounts and forces yielding the kinds of control surface deflections achieved on the accident airplane. But no matter what the proper answers are for these concerns, I have yet to understand why anyone would think that maximum control deflection, and repeated reversals, in all three axes, at the same time, was anything close to expected professional aviation behavior - below, at, or above design maneuvering speed.

[Grunf]

...
Later when with an identical Aircraft based in NY, and operating identical routes to the AA Aircraft, was when we had all the maintenance problems with the composite tail, not in Australia.

I do not know about the possibility of a tail coming off a B747, B737 or any other Airbus, and would never comment on such, however no matter how much you all ridicule me, I do KNOW that with an identical Aircraft (A300-600), operating out of the same Airport (JFK) and operating the same routes (down through the Caribbean), we had lots of maintenance problems with the tail, and I honestly feel this is a hell of a coincidence IF as you all say, this could not have possibly played a part in it.


OK, if I can add my 2cents / 2 ps:
Airsupport, it seems that your case is a subcase of the general potential problem and that is flying outside of design envelope.

Both ground and flight test are there to prove that design is within the required cert requirements. If for any reason these loads are exceeded (either by pilot input or by other means i.e. engine malfunction, weather etc) structure may (and probably will) fail.

In some fortunate cases when OEM designed structure based on conceptual loads which after the test turn to be far too big (one would think of some older aircraft, like most of the 747 structure) these exceeding loads can be sustained but I think that in that case pilots are required to report overloading.

Only case I know of in which structure is submitted to deliberate failure is the wing breaking after the ground tests are completed. Even in that case, from my experience, several times before the test few tries are made in order to predict the exact load at which the wing will break. This looks good when the real breaking is performed in front of selected guests. A good show off and a huge amount of useful data as well.

Sad occasion when an aircraft fails in flight test (few of Bombardier's examples come to mind, right MFS?) is a good proof of a statement about necessity of staying within the loads envelope.

IMHO one's experience with a specific model in a specific situation (A300-600 flying from JFK to Caribbean) is necessary for a conclusion but not sufficient, to borrow the expression. I can stand behind this statement from the certification standpoint (OEM side, Stress/Structure in particular).

... But no matter what the proper answers are for these concerns, I have yet to understand why anyone would think that maximum control deflection, and repeated reversals, in all three axes, at the same time, was anything close to expected professional aviation behavior - below, at, or above design maneuvering speed.

AirRabbit, you're right on. From the standpoint of what are the loads for which we design, and in my case analyze, the structure - no combination of loadcases is used i.e. when you design you use a set of SEPARATE loadcases for which you performthe analysis.

There are NO COMBINATIONS, otherwise you will have a hell of a certification task. Quite impossible even if you try. I've seen that tried only once long time ago, and in an environment that was not exposed to cert requirements used in civilian/commercial use (military project). Namely, someone thought of running two loadcases for the structure simultaneously and guess what happened? Total failure and consequent postponement of a project for several months.

You always assume a discreet set of load cases, defined on requirements from relvant FAR/JAR or other document required by local CAA. So, applying simultaneous maneuvers in this case or simultaneous loadcases, in general, is not acceptable.

I fully agree that under circumstances any structure would behave the same as the one on A300-600. You are maybe right when you pinpoint the characteristics of A300 fin design (I am not familiar with it appart from what was published based on this accident) but I do not think this was decisive.

In fact, just to support that statement I know of at least one case of analysis done for new or modified structure bearing in mind this specific accident. Result was failure. By the way, it was a metallic structure, in use for several years.

Cheers

[airsupport]

Only case I know of in which structure is submitted to deliberate failure is the wing breaking after the ground tests are completed. Even in that case, from my experience, several times before the test few tries are made in order to predict the exact load at which the wing will break. This looks good when the real breaking is performed in front of selected guests. A good show off and a huge amount of useful data as well.

There are other similar tests, on the B767 for example, I was working at Boeing when they did those tests and also a structural test on the fuselage, where they pressurize a fuselage until something lets go, in the B767 it was just near the rear door.

These are tests done on new build structures, yes they put them through simulated cycles, but not (obviously) actual flights.

I do not even really understand, or want to understand what this Pilot did, I am not a Pilot and don't really care IF you blame him or not.

However, after working on these A300-600s out of JFK, I cannot help but wonder if the problems I mentioned before played a part in it, that is no matter who caused what on that tragic day, it was a disaster waiting to happen.

[theamrad]

Knowing all that I've come to know about this whole situation, including reading the transcripts of all the public hearings - from a mainly engineering standpoint, I have to say that I have always been perplexed and worried about the direction in which fault was placed.

As would have become apparent to the board during the progression of the investigation - the A300 had more than it's fair share of exceedances of limit load for the vert stabiliser. Strange considering what Limit load is supposed to mean!

The issue of how control pressure/deflection is varied with speed on the A300 has always smacked of the illogical (to say the least IMO) when compared with the usual Boeing method. When the issue of 'harmonisation' of all control responses through speed changes is used to justify the approach used by Airbus - it just begs the response in my mind - but B' managed it without making a particular control input ridiculously OVERsensitive. Why could airbus not go down the same route of load limiting?

As far as AA's pre-accident upset training is concerned - (with reference esp. to evidence given during the public hearings): I personally could never have had any other impression from that material than the use of rudder was only to be made in a smooth and progressive manner AND only after aileron inputs(up to full) had made no impression on 'wayward' roll. Furthermore, I fail to see how anyone "exposed" to that training could have had the impression that rudder was being described as a primary means of roll control - quite the contrary IMHO. I think the suggestion by the board that this first officer or any other pilot could have learned to 'play footsie' with the rudder after this training is an insult to anyone's intelligence, and disingenuous to say the least.

As suggested during the course of the investigation, the lack of totally reliable/continuous data about the actual accelerations and perceptions which the flight crew experienced, call into question the confidence with which control inputs can be criticised. I believe in the face of the available evidence we cannot know whether ANY rudder inputs were justified - or whether the crew even knew that, for example, in trying to counter pilot induced adverse yaw after a first reaction - full oscillations were in fact being made (IMHO due to the oversensitive mechanism).

I just hate the fact that I think the pilot was unfairly blamed.