Interesting note about AA Airbus crash in NYC
Join Date: Dec 2006
Location: washington,dc
Posts: 486
Likes: 0
Received 0 Likes
on
0 Posts
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!
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!
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
[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.
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.
Psychophysiological entity
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.
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.
Join Date: Aug 2005
Location: fairly close to the colonial capitol
Age: 55
Posts: 1,693
Likes: 0
Received 0 Likes
on
0 Posts
...... 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.
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.
Last edited by vapilot2004; 8th Jan 2007 at 19:45.
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: May 2005
Location: World
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
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.
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: May 2005
Location: World
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
oops, previous post, and this post, from -
http://www.iasa.com.au/folders/Safet...stability.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]
http://www.iasa.com.au/folders/Safet...stability.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]
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
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?
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
http://www.ntsb.gov/events/2001/AA58...its/241835.pdf
Contains a graph showing pedal travel limitation vs. IAS.
Psychophysiological entity
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 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.
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.
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Join Date: May 2005
Location: World
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
The PF got full rudder -- whether that was what he wanted or expected from his inputs is another question.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Moderator
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.
(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.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
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.)
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.)
Moderator
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.
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.
Join Date: Aug 2005
Location: fairly close to the colonial capitol
Age: 55
Posts: 1,693
Likes: 0
Received 0 Likes
on
0 Posts
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.
(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.
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.
