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Interesting note about AA Airbus crash in NYC

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Interesting note about AA Airbus crash in NYC

Old 22nd Dec 2006, 15:13
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Interesting note about AA Airbus crash in NYC

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/citation...burgh_cit.html
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Old 22nd Dec 2006, 16:00
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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...
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Old 22nd Dec 2006, 19:24
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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)
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Old 22nd Dec 2006, 19:55
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Do you need it placarded to say "Pull stick back to raise the nose"?
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Old 22nd Dec 2006, 20:09
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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.
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Old 22nd Dec 2006, 20:38
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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!

Last edited by jondc9; 22nd Dec 2006 at 22:39. Reason: changed terrible to mediocre
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Old 22nd Dec 2006, 20:48
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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.
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Old 22nd Dec 2006, 21:43
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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.
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Old 22nd Dec 2006, 23:08
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Originally Posted by barit1 View Post
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).
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Old 22nd Dec 2006, 23:11
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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, 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.
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Old 22nd Dec 2006, 23:21
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Found it:

http://www.cs.york.ac.uk/hise/safety...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)
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Old 23rd Dec 2006, 00:44
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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?
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Old 23rd Dec 2006, 02:12
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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.
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Old 23rd Dec 2006, 03:07
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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.
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Old 23rd Dec 2006, 06:05
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Arrow

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).
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Old 23rd Dec 2006, 11:08
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Well, gentlemen, DozyWanabe posted excellent link 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!

Last edited by Clandestino; 23rd Dec 2006 at 11:21. Reason: Whhooooops! Wrong button!
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Old 23rd Dec 2006, 13:43
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Originally Posted by Ignition Override View Post
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.
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Old 23rd Dec 2006, 14:36
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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.
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Old 23rd Dec 2006, 14:53
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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.
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Old 23rd Dec 2006, 15:37
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"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.

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