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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 31st Dec 2006, 18:17
  #101 (permalink)  
 
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Originally Posted by bomarc View Post
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?
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Old 1st Jan 2007, 01:45
  #102 (permalink)  
 
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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.
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Old 1st Jan 2007, 01:54
  #103 (permalink)  
 
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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"?
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Old 1st Jan 2007, 04:14
  #104 (permalink)  
 
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Originally Posted by bomarc View Post
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.
Originally Posted by bomarc View Post
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?
Originally Posted by bomarc View Post
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!
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Old 1st Jan 2007, 15:49
  #105 (permalink)  
 
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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?
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Old 1st Jan 2007, 16:27
  #106 (permalink)  
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Originally Posted by bomarc View Post
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.
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Old 1st Jan 2007, 16:35
  #107 (permalink)  
 
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Originally Posted by bomarc View Post
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.
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Old 1st Jan 2007, 17:00
  #108 (permalink)  
 
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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.
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Old 1st Jan 2007, 19:11
  #109 (permalink)  
 
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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?
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Old 1st Jan 2007, 22:32
  #110 (permalink)  
 
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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?
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Old 1st Jan 2007, 22:56
  #111 (permalink)  
 
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Originally Posted by pontifex View Post
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.
Originally Posted by arcniz View Post
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.
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Old 1st Jan 2007, 23:56
  #112 (permalink)  
 
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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.
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Old 2nd Jan 2007, 08:22
  #113 (permalink)  
 
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Originally Posted by cornwallis View Post
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
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Old 2nd Jan 2007, 09:13
  #114 (permalink)  

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Which aircraft will stand it then?

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.
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Old 2nd Jan 2007, 10:12
  #115 (permalink)  
 
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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!
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Old 2nd Jan 2007, 13:44
  #116 (permalink)  
 
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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!
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Old 2nd Jan 2007, 21:57
  #117 (permalink)  
 
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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.
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Old 3rd Jan 2007, 00:07
  #118 (permalink)  
 
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Originally Posted by bomarc View Post
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?

Last edited by AirRabbit; 3rd Jan 2007 at 03:53.
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Old 3rd Jan 2007, 08:44
  #119 (permalink)  
 
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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?
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Old 3rd Jan 2007, 09:19
  #120 (permalink)  

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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.
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