He stepped on the Rudder and redefined Va
Something I'm finding very disturbing about this thread is the suggestion/implication that the NTSB and FAA are incompetent or corrupt. I'm wondering how many of the people making these suggestions have actually dealt with the FAA during an aircraft certification, or worked with the NTSB during an air safety investigation?
Having done both (I became a DER 25 years ago and I've been involved in multiple air-safety investigations), I find the implications insulting to those involved. My experiences have been just the opposite - people obsessed with covering every possible detail, with impeccable ethics and integrity.
Bubbers, do you honestly believe no one in the NTSB considered the possibility that the rudder movements were uncommanded, and looked at data/research that convinced them otherwise? Does Teldorserious really think that they faked the data that said the tail failed at 2.2x design load (well above the FAR mandated 1.5x)? These are not mindless government agencies we're talking about - they are real flesh and blood people. People that know that other peoples lives literally depend on them getting it right.
Now, that doesn't mean I always agree with the FAA/NTSB - heck I can think of times when the FAA and NSTB couldn't agree with each other, and even times when different branches of the FAA couldn't agree with each other. But these fell into the realm of honest differences of opinion between engineers - something that happens with some regularity between even the best engineers.
So, before you make another post slandering these people, you might want to think about what exactly you're posting.
As for aircraft design parameters that would allow a pilot (or terrorist) to break an airplane tail on purpose, it seems to me that a pilot (or terrorist in control of an aircraft) has the ability to intentionally crash an airplane pretty much any time they want, no matter how strong we make the tail
Having done both (I became a DER 25 years ago and I've been involved in multiple air-safety investigations), I find the implications insulting to those involved. My experiences have been just the opposite - people obsessed with covering every possible detail, with impeccable ethics and integrity.
Bubbers, do you honestly believe no one in the NTSB considered the possibility that the rudder movements were uncommanded, and looked at data/research that convinced them otherwise? Does Teldorserious really think that they faked the data that said the tail failed at 2.2x design load (well above the FAR mandated 1.5x)? These are not mindless government agencies we're talking about - they are real flesh and blood people. People that know that other peoples lives literally depend on them getting it right.
Now, that doesn't mean I always agree with the FAA/NTSB - heck I can think of times when the FAA and NSTB couldn't agree with each other, and even times when different branches of the FAA couldn't agree with each other. But these fell into the realm of honest differences of opinion between engineers - something that happens with some regularity between even the best engineers.
So, before you make another post slandering these people, you might want to think about what exactly you're posting.
As for aircraft design parameters that would allow a pilot (or terrorist) to break an airplane tail on purpose, it seems to me that a pilot (or terrorist in control of an aircraft) has the ability to intentionally crash an airplane pretty much any time they want, no matter how strong we make the tail
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tdracer Please accept my compliments for a well worded and very well positioned post.
There are some here who are somewhat more knowledgeable about some things whereas others may not be and thats simply a fact of life. Throwing insults at peopole or organizations just because the work they do may not be understood or appreciated is the height of ignorance spiced with laziness. Thanks for bringing a level head to the table.
As Ive been trying to convince some here, this accident was NOT caused by the wingtip vortices generated by the preceding JAL747. Yes, that preceding airplane did generate wingtip vortices and yes, AA587 encountered both of them. The first encounter was handled professionally and rather easily by the pilot flying (the F/O) and his response was precisely what he was taught. However, the second encounter was not handled well at all and it was contrary to what he had been trained to do. He was trained - and he did perform correctly the first time. The question should be, why did he do almost the opposite of what he had just done very successfully?
Additionally, there are some here who stubbornly hold to the concept that the rudder displacements clearly seen on the FDR were a result of the vortex encounter not rudder pedal inputs. HOWEVER, as Ive also been trying to convey to these folks, the rudder was displaced by the pilot flying and done deliberately (and could easily be described as a panic response which is what I believe caused him to respond so distinctively different from the way he had just responded to exactly the same kind of stimulus) all of which were excessive, and most of which were at - or beyond - the control limits and reversed each of those inputs at least 5 times in a 7 second period. And, before those same naysayers jump on this issue claiming that rudder pedal position is not an FDR parameter YES IT IS. While it wasnt originally installed on the A300-600 at construction, American DID install a modification (to be in compliance with the requirement that was to soon become effective) that recorded the control wheel, control column, and rudder pedal positions on the FDR. And NO, these are not back-driven controls and that is the reason for the requirement for the completing the FAA-mandated modification to be able to record those control position inputs as well as the resulting control surface positions. The FDR clearly shows that the rudder pedals were used to command the rudder surface position. In fact, the NTSB had produced an animation of the FDR readouts showing the cockpit controller positions (column, wheel, and pedal) as well as rudder position with superimposed markers showing the relevant control limitations that adjusted as airspeed increased. I used to have a copy of that animation but I dont have it with me. Perhaps some here may have or know how to acquire that animation it shows what happened quite clearly ... and it is quite sobering.
As many have said here I, too, get no satisfaction out of criticizing another aviator but facts are facts and we can choose to ignore them or examine them. Personally, Id prefer to examine them and learn, if we can, why a well-trained aviator could become so easily panicked as to do what this well trained and otherwise competent aviator did.
Sure, we can criticize training programs ... and simulators ... and instructors all day but unless we know the facts such criticisms are simply howling at the moon a lot of noise, drawing some attention, and accomplishing nothing.
There are some here who are somewhat more knowledgeable about some things whereas others may not be and thats simply a fact of life. Throwing insults at peopole or organizations just because the work they do may not be understood or appreciated is the height of ignorance spiced with laziness. Thanks for bringing a level head to the table.
As Ive been trying to convince some here, this accident was NOT caused by the wingtip vortices generated by the preceding JAL747. Yes, that preceding airplane did generate wingtip vortices and yes, AA587 encountered both of them. The first encounter was handled professionally and rather easily by the pilot flying (the F/O) and his response was precisely what he was taught. However, the second encounter was not handled well at all and it was contrary to what he had been trained to do. He was trained - and he did perform correctly the first time. The question should be, why did he do almost the opposite of what he had just done very successfully?
Additionally, there are some here who stubbornly hold to the concept that the rudder displacements clearly seen on the FDR were a result of the vortex encounter not rudder pedal inputs. HOWEVER, as Ive also been trying to convey to these folks, the rudder was displaced by the pilot flying and done deliberately (and could easily be described as a panic response which is what I believe caused him to respond so distinctively different from the way he had just responded to exactly the same kind of stimulus) all of which were excessive, and most of which were at - or beyond - the control limits and reversed each of those inputs at least 5 times in a 7 second period. And, before those same naysayers jump on this issue claiming that rudder pedal position is not an FDR parameter YES IT IS. While it wasnt originally installed on the A300-600 at construction, American DID install a modification (to be in compliance with the requirement that was to soon become effective) that recorded the control wheel, control column, and rudder pedal positions on the FDR. And NO, these are not back-driven controls and that is the reason for the requirement for the completing the FAA-mandated modification to be able to record those control position inputs as well as the resulting control surface positions. The FDR clearly shows that the rudder pedals were used to command the rudder surface position. In fact, the NTSB had produced an animation of the FDR readouts showing the cockpit controller positions (column, wheel, and pedal) as well as rudder position with superimposed markers showing the relevant control limitations that adjusted as airspeed increased. I used to have a copy of that animation but I dont have it with me. Perhaps some here may have or know how to acquire that animation it shows what happened quite clearly ... and it is quite sobering.
As many have said here I, too, get no satisfaction out of criticizing another aviator but facts are facts and we can choose to ignore them or examine them. Personally, Id prefer to examine them and learn, if we can, why a well-trained aviator could become so easily panicked as to do what this well trained and otherwise competent aviator did.
Sure, we can criticize training programs ... and simulators ... and instructors all day but unless we know the facts such criticisms are simply howling at the moon a lot of noise, drawing some attention, and accomplishing nothing.
Last edited by AirRabbit; 4th Oct 2013 at 04:10.
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CAUTION
The sudden revered of rudder direction at high rudder deflections, due to improper rudder application or abrupt release, can result in overstressing the vertical fin. This condition could be brought about during recovery attempts from a flight condition induced by a lateral control malfunction.
The KC-135 is a *Boeing*
This revision was published on 30 June 2000.
That was more than a year before the AA587 crash.
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The FDR records position of *both* the *rudder* and the *Rudder pedals*
The FDR positions from the accident of *both* the Rudder and rudder pedals agree.
The Yaw Damper acts through an averaging mechanism which prevents yaw damper movements from moving the rudder pedals.
If the yaw damper moved the rudder, the pedals would not have moved
The rudder pedals moved.
Even though that is contradicted by all the evidence.
Yes, the NTSB did
Yes, the NTSB did
They did
Sorry to keep repeating, but this has all been posted before. How many more times does this have to be repeated before you read what is being posted?
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bubbers
One has to admire your tenacity in defending your colleagues, but I fear you are now clutching at straws. As has been said several times both pedal position and rudder deflection were recorded and reported. This is an extract from the Performance Group's appendix to the NTSB report - sorry I don't seem to be able to make it smaller.
Bearing in mind the qualifications described in that report (different sampling times, yaw damper influence etc.) by any reasonable judgement the rudder deflection followed the pedal inputs. No system malfunction here!
One has to admire your tenacity in defending your colleagues, but I fear you are now clutching at straws. As has been said several times both pedal position and rudder deflection were recorded and reported. This is an extract from the Performance Group's appendix to the NTSB report - sorry I don't seem to be able to make it smaller.
Bearing in mind the qualifications described in that report (different sampling times, yaw damper influence etc.) by any reasonable judgement the rudder deflection followed the pedal inputs. No system malfunction here!
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roulis
Dutch roll is certainly an oscillation, but it doesn't have to be one of increasing bank; in fact it would be a lousy aircraft for which that were true - very probably unflyable. Increasing bank as a result of suitably (mis)timed pilot inputs is quite another thing.
Sure the rolling motion is usually the most obvious sign of a dutch roll, but the motion is a combination of two oscillations - one around the roll axis and the other around the yaw - linked together by a common driver - sideslip.
Way back in the 1950s Ashkenas and McRuer established the importance of the roll/sideslip ratio as a parameter to describe the goodness/badness of dutch roll. The larger the number the worse the aircraft basically. So dutch roll can be triggered by rudder application, but as you say it is best controlled by aileron.
So far as I know, the A300 was not noted as having poor dutch roll characteristics.
A real dutch roll is an OSCILLATION from one side to another with increasing bank due to resonance.
Despite you have a yaw movement in the dutch roll, the names says it well it s a ROLL oscillation, to be corrected with the stick not with pedals.
Despite you have a yaw movement in the dutch roll, the names says it well it s a ROLL oscillation, to be corrected with the stick not with pedals.
Sure the rolling motion is usually the most obvious sign of a dutch roll, but the motion is a combination of two oscillations - one around the roll axis and the other around the yaw - linked together by a common driver - sideslip.
Way back in the 1950s Ashkenas and McRuer established the importance of the roll/sideslip ratio as a parameter to describe the goodness/badness of dutch roll. The larger the number the worse the aircraft basically. So dutch roll can be triggered by rudder application, but as you say it is best controlled by aileron.
So far as I know, the A300 was not noted as having poor dutch roll characteristics.
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Nope, in investigating an accident resulting from rudder movement, it just never occurred to the NTSB to examine part of the autopilot which actuates the rudder.
That's sarcasm. Of course they examined the a/p rudder actuator. The clutching mechanism was disengaged. Read about it in Addendum #5 in the Systems group Factual Report.
That's sarcasm. Of course they examined the a/p rudder actuator. The clutching mechanism was disengaged. Read about it in Addendum #5 in the Systems group Factual Report.
LSM,
I trust you meant American Airlines pilots are infallible. Lots of us mere mortal American pilots make mistakes, sometimes, with a blue moon shining.
I trust you meant American Airlines pilots are infallible. Lots of us mere mortal American pilots make mistakes, sometimes, with a blue moon shining.
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Putting that case in historical context, it can be seen almost as an aberration - as in accident reports both prior and following, the NTSB (post-separation from the FAA) showed no significant bias towards one party or the other.
Much the same could be said of the French BEA and AF296 (except in that case they made the correct call, but it didn't end the controversy).
Last edited by DozyWannabe; 4th Oct 2013 at 18:38.
Thanks Dozy - I had to Google that one (the only "Hoot" Gibson I knew of was the Space Shuttle pilot - I have a SS model around he that he autographed 
).
After I found the Wiki, I vaguely remember hearing about that incident (I was a young, fresh faced engineer at the time) but didn't know it had become so controversial. There was a story going around Boeing at the time that the crew "accidentally" erased the voice recorder after landing (no idea if it has any truth). Doesn't sound like the NTSB's finest hour
.
).After I found the Wiki, I vaguely remember hearing about that incident (I was a young, fresh faced engineer at the time) but didn't know it had become so controversial. There was a story going around Boeing at the time that the crew "accidentally" erased the voice recorder after landing (no idea if it has any truth). Doesn't sound like the NTSB's finest hour
.
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IIRC, it came to light many years later that if certain electrical systems were damaged and the ground crew shut the power down then the CVR would automatically erase the tape.
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how off course are we now?
Famous Hoot Gibson maneuver...well boys the plane went through hell and they all came out alive. Good for the plane
Anyone remember the 60 minute Hoot Gibson interview? I do..he said straight to the camera..."every CFI out there thinks I did it, well I didn't...it was the rudder".
Has anyone posted the dissenting opinion of one of the NTSB members on the airbus thing?
Do consider one thing ...on the preceding page one of the posters says the FO did the correct thing on the first wake encounter...and did something different during the second...why would he?
Lots of graphs, reports and other things...but very little on the human side.
If you do something right the first time, why change? Did he panic? Did he have itchy feet?
Interviews with other pilots? Sorry, I've seen too many pilots say different things because it helps their own "six".
Famous Hoot Gibson maneuver...well boys the plane went through hell and they all came out alive. Good for the plane
Anyone remember the 60 minute Hoot Gibson interview? I do..he said straight to the camera..."every CFI out there thinks I did it, well I didn't...it was the rudder".
Has anyone posted the dissenting opinion of one of the NTSB members on the airbus thing?
Do consider one thing ...on the preceding page one of the posters says the FO did the correct thing on the first wake encounter...and did something different during the second...why would he?
Lots of graphs, reports and other things...but very little on the human side.
If you do something right the first time, why change? Did he panic? Did he have itchy feet?
Interviews with other pilots? Sorry, I've seen too many pilots say different things because it helps their own "six".
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