AMR 587 Airbus Crash (merged)
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"Airbus posts no speed limit other than the normal gear door limits (270 knots) and says nothing about slowing down to apply rudder. The manual says the rudder load limiter will protect us in its description of the rudder load limiter."
Wino
Thanks for the above. That is exactly what I expected, and while there was some back and forth comment, I am surprised that AA or the Pilots Assn. did not really hold Capt. Jacob’s feet
to the fire during his testimony. How can he infer fault with rudder movement when their own procedure call for similar actions? Is one to believe that on a Bus slide slip and yaw is acceptable and safe when wrestling with a gear problem, but taboo if used to aid in arresting an upset condition involving roll. Where and how do you draw the line. AA seemed to be saying that their SIM training suggested active rudder use due to the degree of roll airman are put into, 90 degrees. I never did understand why and where AirBus found fault with this procedure, other than their position that the SIM did not accurately reflect real world conditions at that AOA.
Wino
Thanks for the above. That is exactly what I expected, and while there was some back and forth comment, I am surprised that AA or the Pilots Assn. did not really hold Capt. Jacob’s feet
to the fire during his testimony. How can he infer fault with rudder movement when their own procedure call for similar actions? Is one to believe that on a Bus slide slip and yaw is acceptable and safe when wrestling with a gear problem, but taboo if used to aid in arresting an upset condition involving roll. Where and how do you draw the line. AA seemed to be saying that their SIM training suggested active rudder use due to the degree of roll airman are put into, 90 degrees. I never did understand why and where AirBus found fault with this procedure, other than their position that the SIM did not accurately reflect real world conditions at that AOA.
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Some impressions from listening to some of the 2nd and 3rd days of the AA587 NTSB hearing, and later looking at some of the on-line material including the “Reconstruction video” of the flight.
Reconstruction video: This shows “pictures” of the plane and the attitude indicator, together with graphic displays of positions of the rudder pedals and rudder, as well as the vertical and lateral accelerations of the a/c, all derived from FDR data. One of the most interesting features (to me) is that you can see the operation of the yaw damper/auto-coordination system on the ground. As the a/c exits the taxiway it does a 180º right turn onto the runway, during which the rudder deflects left without the rudder pedals moving, i.e. the system thinks the a/c is yawing right (nose right) and tries to correct. When the a/c holds (stops) on the runway the rudder makes a large deflection right which then slowly decays to zero, again without the rudder pedals moving.
During the first wake encounter the rudder makes only tiny movements. Evidently feet were on the pedals but they were used with great restraint.
The second wake encounter is extremely short, about ten seconds from start to fin separation. Its so quick that its hard to see exactly what happens, and I have not found any way to slow the video down. In contrast to the first encounter, extreme coordinated yoke and rudder movements are used almost from the start. The delay between a rudder pedal movement and the consequent rudder movement can be seen. The delay is apparently due to digital processing. It was stated in the hearing that pilot induced oscillations are always more of a concern in fly-by-wire a/c because of this delay. The delay usually has to be reduced to less than 1/10 second. It was also stated that with PIO it is possible to reach limit loads in two cycles and ultimate loads in four cycles.
Vertical Motion Simulator: FDR data are used to back drive a simulator specially suited to reproducing large-amplitude vertical motion. The observers noted that on take-off from JFK 31L the runway roughness was much less than they knew it to be from experience, probably due to the filtering of the FDR data on the a/c and/or limitations in the simulator. They thought the encounter with the first wake felt like a wake encounter. In contrast, they did not feel anything in the second encounter that would justify the extreme yoke and rudder pedal movements recorded. They described these movements as being more typical of an avoidance maneuver.
Wakes from JAL47: The atmospheric conditions were favorable for stable wakes, and it was estimated that 63% of the original energy was still in the wake in both encounters. However, the maximum velocity was estimated to be only 10 m/s (about 20 kts), and too low to be of any concern to the a/c structure. The a/c crossed the wakes at very narrow angles, so that it was almost flying along the wake. One structures witness stated he was not aware of any study of the effects of wakes on structure while in a yaw.
FAR25: It seemed that everybody worked from the regulations only. The FAA decided in the 1950’s that there had to be some standards as to what a/c have to be able to do in order to carry people about, and started to list certain maneuvers, which become the “envelope”. Because manufacturing a/c is a competitive business, manufactures design to this “envelope” and little more, or they will not be competitive. The aircrew are then assumed to stay within the envelope. This whole approach was best illustrated by the first sentence of Mr. Winkler’s prepared presentation, “The most important thing for an a/c structure is that it should be strong enough to resist all load conditions as required by FAR25”. He did not say “strong enough to withstand possible loads“. The same with maintenance. Anything which happens outside the envelope is “non-scheduled maintenance”, e.g. being hit by a truck on the ground. I am not commenting on this, just stating everybody’s attitude.
One question posed to the hearing but not directed to any particular individual was, “how can we continue to certify an a/c which can be broken by use of its certified flight controls?”. The answer given was along the lines that it has always been the case that a/c can be broken by use of the pitch controls. The pilot has always been expected to stay within the pitch envelope. It struck that this is like the case of a bus - you rely on the driver not to drive over a cliff. But perhaps a better analogy is a ship, where a storm may put you on the rocks whatever you do. But at least a ship Captain does not expect the rudder to fall off if he goes “hard a port”. (Continued in the next post.)
One the most interesting (to me) on-line documents is an (undated) talk by Captain William Wainwright, Chief Pilot of Airbus Industrie. I have no idea if this is old or recent. Here are some extracts. The omission of text in these extracts is indicated by “………”.
--------- Start of quote extracts -----------
AIRPLANE UPSET RECOVERY TRAINING AID, By Captain William Wainwright, Airbus Industrie.
INTRODUCTION
The idea for a joint industry working group to produce an Airplane Upset Recovery Training Aid was first proposed by ATA in June 1996. ,,,,,,,,,.The end result of 2 years work is a training package including a video and a CD-ROM, giving an airplane upset recovery training aid. This package is on free issue to all of you, to use or not to use as you wish. ………..The content of the package is not my subject today, but there are a few issues of general interest which I gained from my experience as a member of the working group which I would like to talk about.
2. THE BEGINNING
…… Right from the beginning there was a conflict between the technical advice given by the manufacturers' training pilots and that expressed by those of the principal airlines already practicing upset training. They naturally considered themselves to be the experts on this subject, based on the many .hours of training that they had already conducted on a large number of pilots in their simulators. At the beginning of 1997, the Flight Test Departments were asked to come in to support their training pilots. From then on, the chief test pilots of the 3 major manufacturers became members of the working group; XXX of Boeing, YYY of McDonnell-Douglas (now Boeing - Douglas Products), and myself. But the conflict over the different opinions on aircraft handling and recovery techniques continued for a long time until we finally achieved agreement at the last meeting in January 1998. The reasons for these differences of opinion are the subject of my talk today.
3. THE DIFFERENCES
The differences of opinion were mainly concentrated in the following areas:
(a) Procedures versus general advice.
(b) Ease of training versus failure cases.
(c) Stalling.
(d) Use of rudder.
(e) Use of simulators.
It is worth saying that there was never any difference of opinion between the 3 test pilots on the group. Although we come from different backgrounds and have worked in different organisations with different work cultures, we always agreed on our technical advice. ………………………..
6. STALLING
Another aspect that was being ignored in the existing training was the stall. ……… However, the technique being taught only works if the aircraft is not stalled. ………….This is something that we are well aware of in testing, but it was either being totally ignored, or misunderstood. I consider the inclusion of this note to be one of our most important contributions. ………
7. USE OF RUDDER
We also spent a lot of time discussing the use of rudder. The existing training courses all emphasised using rudder for roll control at low speeds. It is true that the rudder remains effective down to very low speeds, and fighter pilots are accustomed to using it for "scissor" evasive manoeuvres when flying not far from the stall. But large airliners, with all the inertias that they possess, are not like fighter aircraft. Based on our experience as test pilots we are very wary of using rudder close to the stall. It is the best way to provoke' a loss of control if not used very carefully, particularly with flaps out. We finally got the training managers to agree to play down the use of rudder in their existing courses. But we do not say never use the rudder at low speed. We say that, if necessary, the aileron inputs can be assisted by coordinated rudder in the direction of the desired roll, We also caution that "excessive rudder can cause excessive sideslip, which could lead to departure from controlled flight".
But why did we have so much difficulty in convincing the training pilots that it is not a good idea to go kicking the rudder around at low speed? Their reply was always the same; “but it works in the simulator“. This leads me on to my last point.
8. USE OF SIMULATORS
We manufacturers were very concerned over the types of manoeuvres being flown in simulators and the conclusions that were being drawn from them. Simulators, like any computer system, are only as good as the data that goes into them. That means the data package that is given to the simulator manufacturer. And we test pilots do not deliberately lose control of our aircraft just to get data for the simulator. …………..
The complete data package includes a part that is drawn from actual flight tests, a part that uses wind tunnel data, and the rest which is pure extrapolation. If should be obvious that conclusions about aircraft behaviour can only be drawn from the parts of the flight envelope that are based on hard data. This in fact means being not far from the centre of the flight envelope; the part that is used in normal service. It does not cover the edges of the envelope. I should also add that most of the data actually collected in flight is from quasi-static manoeuvres. Thus, dynamic manoeuvring is not very well represented. …………
In other words, you have reasonable cover up to quite high sideslips and quite high AOAs, but not at the same time. Furthermore, the matching between aircraft stalling tests and the simulator concentrates mainly on the longitudinal axis. This means that the simulator model is able to correctly reproduce the stalling speeds and the pitching behaviour, but fidelity is not ensured for rolling efficiency (based on a sirrpfified model of wind tunnel data) or for possible asymmetric stalling of Ihe wings. Also, the engine out range is much less than !he all engines operating one, and linear interpolation is assumed between low and high Mach numbers. Wind tunnel data goes further. ,,,,,,,,,,,,,,,,,,,,
In fact, this is a perfectly adequate coverage to conduct all normal training needs. But it is insufficient to evaluate recovery techniques from loss of control incidents. Whereas, the training managers were all in the habit of demonstrating the handling characteristics beyond the stall; often telling their trainees that the rudder is far more effective than aileron and induces less drag and has no vices In short, they were developing handling techniques from simulators that were outside their guaranteed domain. Simulators can be used for upset training, but the training should be confined to the normal flight envelope; For example, training should stop at the stall warning. They are "virtual" aircraft and they should not be used to develop techniques at the edges of the flight envelope. This is work for test pilots and flight test engineers using their knowledge gained from flight testing the "real" aircraft.
--------- End of quote extracts -----------
Several test pilots (some USA) made the point (if I understood them correctly) that pilots do not make control inputs of set amounts. They make a control input and wait to see what happens. On the basis of the result they then make another input. And so on. They do not just stamp on the pedals. So to some extent it may be argued that it should not matter what the rudder travel gearing is. Certainly the Airbus Industrie engineering test pilot witness said he was very happy with the present system. On the other hand it seemed to me that events in the reconstruction were happening so fast that a “try-it-and-see" approach wasn’t really possible.
If you got this far you may be amused by a comment by one of the simulator instructors being questioned about the psychology of instruction who said, “I know that pilots have a pretty short attention span, and if you have a point to make you had better get it over early”. This same interviewe said that simulator instructors have no way of telling which behaviors of the simulator are based on data and which on extrapolations.
These are just some personal impressions of the hearing. I was not there.
Reconstruction video: This shows “pictures” of the plane and the attitude indicator, together with graphic displays of positions of the rudder pedals and rudder, as well as the vertical and lateral accelerations of the a/c, all derived from FDR data. One of the most interesting features (to me) is that you can see the operation of the yaw damper/auto-coordination system on the ground. As the a/c exits the taxiway it does a 180º right turn onto the runway, during which the rudder deflects left without the rudder pedals moving, i.e. the system thinks the a/c is yawing right (nose right) and tries to correct. When the a/c holds (stops) on the runway the rudder makes a large deflection right which then slowly decays to zero, again without the rudder pedals moving.
During the first wake encounter the rudder makes only tiny movements. Evidently feet were on the pedals but they were used with great restraint.
The second wake encounter is extremely short, about ten seconds from start to fin separation. Its so quick that its hard to see exactly what happens, and I have not found any way to slow the video down. In contrast to the first encounter, extreme coordinated yoke and rudder movements are used almost from the start. The delay between a rudder pedal movement and the consequent rudder movement can be seen. The delay is apparently due to digital processing. It was stated in the hearing that pilot induced oscillations are always more of a concern in fly-by-wire a/c because of this delay. The delay usually has to be reduced to less than 1/10 second. It was also stated that with PIO it is possible to reach limit loads in two cycles and ultimate loads in four cycles.
Vertical Motion Simulator: FDR data are used to back drive a simulator specially suited to reproducing large-amplitude vertical motion. The observers noted that on take-off from JFK 31L the runway roughness was much less than they knew it to be from experience, probably due to the filtering of the FDR data on the a/c and/or limitations in the simulator. They thought the encounter with the first wake felt like a wake encounter. In contrast, they did not feel anything in the second encounter that would justify the extreme yoke and rudder pedal movements recorded. They described these movements as being more typical of an avoidance maneuver.
Wakes from JAL47: The atmospheric conditions were favorable for stable wakes, and it was estimated that 63% of the original energy was still in the wake in both encounters. However, the maximum velocity was estimated to be only 10 m/s (about 20 kts), and too low to be of any concern to the a/c structure. The a/c crossed the wakes at very narrow angles, so that it was almost flying along the wake. One structures witness stated he was not aware of any study of the effects of wakes on structure while in a yaw.
FAR25: It seemed that everybody worked from the regulations only. The FAA decided in the 1950’s that there had to be some standards as to what a/c have to be able to do in order to carry people about, and started to list certain maneuvers, which become the “envelope”. Because manufacturing a/c is a competitive business, manufactures design to this “envelope” and little more, or they will not be competitive. The aircrew are then assumed to stay within the envelope. This whole approach was best illustrated by the first sentence of Mr. Winkler’s prepared presentation, “The most important thing for an a/c structure is that it should be strong enough to resist all load conditions as required by FAR25”. He did not say “strong enough to withstand possible loads“. The same with maintenance. Anything which happens outside the envelope is “non-scheduled maintenance”, e.g. being hit by a truck on the ground. I am not commenting on this, just stating everybody’s attitude.
One question posed to the hearing but not directed to any particular individual was, “how can we continue to certify an a/c which can be broken by use of its certified flight controls?”. The answer given was along the lines that it has always been the case that a/c can be broken by use of the pitch controls. The pilot has always been expected to stay within the pitch envelope. It struck that this is like the case of a bus - you rely on the driver not to drive over a cliff. But perhaps a better analogy is a ship, where a storm may put you on the rocks whatever you do. But at least a ship Captain does not expect the rudder to fall off if he goes “hard a port”. (Continued in the next post.)
One the most interesting (to me) on-line documents is an (undated) talk by Captain William Wainwright, Chief Pilot of Airbus Industrie. I have no idea if this is old or recent. Here are some extracts. The omission of text in these extracts is indicated by “………”.
--------- Start of quote extracts -----------
AIRPLANE UPSET RECOVERY TRAINING AID, By Captain William Wainwright, Airbus Industrie.
INTRODUCTION
The idea for a joint industry working group to produce an Airplane Upset Recovery Training Aid was first proposed by ATA in June 1996. ,,,,,,,,,.The end result of 2 years work is a training package including a video and a CD-ROM, giving an airplane upset recovery training aid. This package is on free issue to all of you, to use or not to use as you wish. ………..The content of the package is not my subject today, but there are a few issues of general interest which I gained from my experience as a member of the working group which I would like to talk about.
2. THE BEGINNING
…… Right from the beginning there was a conflict between the technical advice given by the manufacturers' training pilots and that expressed by those of the principal airlines already practicing upset training. They naturally considered themselves to be the experts on this subject, based on the many .hours of training that they had already conducted on a large number of pilots in their simulators. At the beginning of 1997, the Flight Test Departments were asked to come in to support their training pilots. From then on, the chief test pilots of the 3 major manufacturers became members of the working group; XXX of Boeing, YYY of McDonnell-Douglas (now Boeing - Douglas Products), and myself. But the conflict over the different opinions on aircraft handling and recovery techniques continued for a long time until we finally achieved agreement at the last meeting in January 1998. The reasons for these differences of opinion are the subject of my talk today.
3. THE DIFFERENCES
The differences of opinion were mainly concentrated in the following areas:
(a) Procedures versus general advice.
(b) Ease of training versus failure cases.
(c) Stalling.
(d) Use of rudder.
(e) Use of simulators.
It is worth saying that there was never any difference of opinion between the 3 test pilots on the group. Although we come from different backgrounds and have worked in different organisations with different work cultures, we always agreed on our technical advice. ………………………..
6. STALLING
Another aspect that was being ignored in the existing training was the stall. ……… However, the technique being taught only works if the aircraft is not stalled. ………….This is something that we are well aware of in testing, but it was either being totally ignored, or misunderstood. I consider the inclusion of this note to be one of our most important contributions. ………
7. USE OF RUDDER
We also spent a lot of time discussing the use of rudder. The existing training courses all emphasised using rudder for roll control at low speeds. It is true that the rudder remains effective down to very low speeds, and fighter pilots are accustomed to using it for "scissor" evasive manoeuvres when flying not far from the stall. But large airliners, with all the inertias that they possess, are not like fighter aircraft. Based on our experience as test pilots we are very wary of using rudder close to the stall. It is the best way to provoke' a loss of control if not used very carefully, particularly with flaps out. We finally got the training managers to agree to play down the use of rudder in their existing courses. But we do not say never use the rudder at low speed. We say that, if necessary, the aileron inputs can be assisted by coordinated rudder in the direction of the desired roll, We also caution that "excessive rudder can cause excessive sideslip, which could lead to departure from controlled flight".
But why did we have so much difficulty in convincing the training pilots that it is not a good idea to go kicking the rudder around at low speed? Their reply was always the same; “but it works in the simulator“. This leads me on to my last point.
8. USE OF SIMULATORS
We manufacturers were very concerned over the types of manoeuvres being flown in simulators and the conclusions that were being drawn from them. Simulators, like any computer system, are only as good as the data that goes into them. That means the data package that is given to the simulator manufacturer. And we test pilots do not deliberately lose control of our aircraft just to get data for the simulator. …………..
The complete data package includes a part that is drawn from actual flight tests, a part that uses wind tunnel data, and the rest which is pure extrapolation. If should be obvious that conclusions about aircraft behaviour can only be drawn from the parts of the flight envelope that are based on hard data. This in fact means being not far from the centre of the flight envelope; the part that is used in normal service. It does not cover the edges of the envelope. I should also add that most of the data actually collected in flight is from quasi-static manoeuvres. Thus, dynamic manoeuvring is not very well represented. …………
In other words, you have reasonable cover up to quite high sideslips and quite high AOAs, but not at the same time. Furthermore, the matching between aircraft stalling tests and the simulator concentrates mainly on the longitudinal axis. This means that the simulator model is able to correctly reproduce the stalling speeds and the pitching behaviour, but fidelity is not ensured for rolling efficiency (based on a sirrpfified model of wind tunnel data) or for possible asymmetric stalling of Ihe wings. Also, the engine out range is much less than !he all engines operating one, and linear interpolation is assumed between low and high Mach numbers. Wind tunnel data goes further. ,,,,,,,,,,,,,,,,,,,,
In fact, this is a perfectly adequate coverage to conduct all normal training needs. But it is insufficient to evaluate recovery techniques from loss of control incidents. Whereas, the training managers were all in the habit of demonstrating the handling characteristics beyond the stall; often telling their trainees that the rudder is far more effective than aileron and induces less drag and has no vices In short, they were developing handling techniques from simulators that were outside their guaranteed domain. Simulators can be used for upset training, but the training should be confined to the normal flight envelope; For example, training should stop at the stall warning. They are "virtual" aircraft and they should not be used to develop techniques at the edges of the flight envelope. This is work for test pilots and flight test engineers using their knowledge gained from flight testing the "real" aircraft.
--------- End of quote extracts -----------
Several test pilots (some USA) made the point (if I understood them correctly) that pilots do not make control inputs of set amounts. They make a control input and wait to see what happens. On the basis of the result they then make another input. And so on. They do not just stamp on the pedals. So to some extent it may be argued that it should not matter what the rudder travel gearing is. Certainly the Airbus Industrie engineering test pilot witness said he was very happy with the present system. On the other hand it seemed to me that events in the reconstruction were happening so fast that a “try-it-and-see" approach wasn’t really possible.
If you got this far you may be amused by a comment by one of the simulator instructors being questioned about the psychology of instruction who said, “I know that pilots have a pretty short attention span, and if you have a point to make you had better get it over early”. This same interviewe said that simulator instructors have no way of telling which behaviors of the simulator are based on data and which on extrapolations.
These are just some personal impressions of the hearing. I was not there.
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PickyPerkins
Your article has to be one of the most informative rudder discussions that I've seen so far. All the years that I spend flying both Boeing and Airbus aircraft and no one ever told me that a rudder could actually separate from an aircraft. Maybe the industry didn’t know or didn’t think that it could happen.
A few years back, I did attend, an Airbus equipment meeting with Airbus test pilots and was surprised how their opinions differed on the interpretation of some of the FMGS information presented on the Airbus aircraft.
It seems that we have a lot more to learn about how airplanes fly...
Cheers .
Your article has to be one of the most informative rudder discussions that I've seen so far. All the years that I spend flying both Boeing and Airbus aircraft and no one ever told me that a rudder could actually separate from an aircraft. Maybe the industry didn’t know or didn’t think that it could happen.
A few years back, I did attend, an Airbus equipment meeting with Airbus test pilots and was surprised how their opinions differed on the interpretation of some of the FMGS information presented on the Airbus aircraft.
It seems that we have a lot more to learn about how airplanes fly...
Cheers .
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Interesting comment about sim instructors...and the rudder.
Suspect that part of the problem is all the old guys have retired and gone to heaven, and the lessons learned a LONG time ago about abrupt maximum rudder use have been forgotten.
Good friend of mine, now retired L10 fleet manager at DAL mentioned that when he joined the airline (was a former Marine pilot), one of his older instructors mentioned ..." be gentle but positive with the rudder." Same for me at PanAmerican, long ago.
Newer guys need to be reminded.
Suspect that part of the problem is all the old guys have retired and gone to heaven, and the lessons learned a LONG time ago about abrupt maximum rudder use have been forgotten.
Good friend of mine, now retired L10 fleet manager at DAL mentioned that when he joined the airline (was a former Marine pilot), one of his older instructors mentioned ..." be gentle but positive with the rudder." Same for me at PanAmerican, long ago.
Newer guys need to be reminded.
ex-Tanker
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There seem to be two inter-related but separate subjects here:
- Should the rudder ever be used to max deflection?
Answer - If neccessary (but this presumes a unidirectional input).
- Should the rudder ever be cycled?
Bearing in mind the gear locking procedure quoted above, the answer must be - One side at a time and then wait in neutral - a continuous cyclic movement can well lead to the separation concerned. (And by the way, a "coordinated turn" won't help the gear locking - because the ball will be in the middle).
We all need to learn more about the use of the rudder - it's a friend if treated right and a fiend if not.
- Should the rudder ever be used to max deflection?
Answer - If neccessary (but this presumes a unidirectional input).
- Should the rudder ever be cycled?
Bearing in mind the gear locking procedure quoted above, the answer must be - One side at a time and then wait in neutral - a continuous cyclic movement can well lead to the separation concerned. (And by the way, a "coordinated turn" won't help the gear locking - because the ball will be in the middle).
We all need to learn more about the use of the rudder - it's a friend if treated right and a fiend if not.
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411a
That quote is what we heard at AA (contrary to Airbus statements and hooplah).
A few other points about the NTSB hearing. THere were some ground rules laid out by the new chair of the NTSB before the hearing which directly restricted the APA's ability to defend their pilot.
I have forgotten the woman's name at this second in time, but she doesnt know anything about airplanes. I hope she knows something about trains and can help out in a train accident because she was worse than useless in this case. One of her ground rules was "I will not let you turn this into an advertisement for beoing." which makes an excellent sound bite.
The problem with this is that AA is the largest airline in the world 800+ jets off 100,000 lbs or greater, and thus has an ENORMOUS body of experience in operating aircraft. More than most countries of the world. Airbus was directly attacking the way that AA operates aircraft and trains their pilots. If it was the training that was the problem, then there should have been other incidents of aircraft exceding design or ultimate loading. And yes there were. There were a total of 7 incidents of aicraft exceding design loading and 2 incidents of aircraft exceding ultimate loading (including 587) on the tails over the last 20 years. The problem is that they were ALL on the airbus fleet of 35 aircraft, and none on the 727/737/757/767,777,MD80/MD11/DC10/DC-9/F100.
That is not a statistical abberation and indicates there is nothing wrong with the techniques employed by pilots in line operations except on one aircraft type. That means there is a problem with the aircraft type, not the pilot corps. Furthermore we were able to identify other incidents in other airline fleets that were simliar to ours. But as this was not to be an "advertisement for boeing" we were forbidden from introducing the evidence.
As to the rudder movements during the first wake and the second wake. It is very likely that during the first wake Sten did not excede breakout force on the rudder pedals, hence the no movement. You may think you are making an application but because you are beneath breakout force you are not, but since the ailerons are still doing the job and the aircraft is going the direction that you expect it to, no further pressure is required. In the second wake he definately exceded the breakout force (probably for the first time in all the years he had been on the aircraft) and the result was not what was expected as the rudder is guaranteed to go to the stop and then all hell breaks loose.
There was also testimony from airbus as I recall that it was possible to go through the rudder load limiter if enough force was applied, which had me "gobsmacked". The only time you should come up against the load limiter is in the heat of battle, and then it should be protecting you from yourself at that point. Hence the whole point of a rudder load limiter . I dont know about other pilots, but in the heat of battle this pilot has an adrenal gland that might make me somewhat stronger than normal.
Cheers
Wino
That quote is what we heard at AA (contrary to Airbus statements and hooplah).
A few other points about the NTSB hearing. THere were some ground rules laid out by the new chair of the NTSB before the hearing which directly restricted the APA's ability to defend their pilot.
I have forgotten the woman's name at this second in time, but she doesnt know anything about airplanes. I hope she knows something about trains and can help out in a train accident because she was worse than useless in this case. One of her ground rules was "I will not let you turn this into an advertisement for beoing." which makes an excellent sound bite.
The problem with this is that AA is the largest airline in the world 800+ jets off 100,000 lbs or greater, and thus has an ENORMOUS body of experience in operating aircraft. More than most countries of the world. Airbus was directly attacking the way that AA operates aircraft and trains their pilots. If it was the training that was the problem, then there should have been other incidents of aircraft exceding design or ultimate loading. And yes there were. There were a total of 7 incidents of aicraft exceding design loading and 2 incidents of aircraft exceding ultimate loading (including 587) on the tails over the last 20 years. The problem is that they were ALL on the airbus fleet of 35 aircraft, and none on the 727/737/757/767,777,MD80/MD11/DC10/DC-9/F100.
That is not a statistical abberation and indicates there is nothing wrong with the techniques employed by pilots in line operations except on one aircraft type. That means there is a problem with the aircraft type, not the pilot corps. Furthermore we were able to identify other incidents in other airline fleets that were simliar to ours. But as this was not to be an "advertisement for boeing" we were forbidden from introducing the evidence.
As to the rudder movements during the first wake and the second wake. It is very likely that during the first wake Sten did not excede breakout force on the rudder pedals, hence the no movement. You may think you are making an application but because you are beneath breakout force you are not, but since the ailerons are still doing the job and the aircraft is going the direction that you expect it to, no further pressure is required. In the second wake he definately exceded the breakout force (probably for the first time in all the years he had been on the aircraft) and the result was not what was expected as the rudder is guaranteed to go to the stop and then all hell breaks loose.
There was also testimony from airbus as I recall that it was possible to go through the rudder load limiter if enough force was applied, which had me "gobsmacked". The only time you should come up against the load limiter is in the heat of battle, and then it should be protecting you from yourself at that point. Hence the whole point of a rudder load limiter . I dont know about other pilots, but in the heat of battle this pilot has an adrenal gland that might make me somewhat stronger than normal.
Cheers
Wino
Last edited by Wino; 7th Nov 2002 at 16:38.
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One year ago:
Looked into some threads started in PPRuNe during past year all dealing with AA 587.
Interesting.
Some contributions a bit far from reality, some more emotional
posts motivated more by sympathy for the poor crew or the company involved rather than dealing with facts. And than those brilliant tech. theories or explainations indicating profound system
knowledge and competence.(i.e. BELGIQUE, JOHN TULLAMARINE and others).
In a thread "witnesses saw AA 587 exlpode in flames" JAN2002
I wrote:
"I dare say during the next weeks the profs will circle again around those AA-Procedures you all heard about: the recovery out of unusual attitudes by applying full rudder. Believe me, the Airbus A 300-600 got a huge one and after takeoff you better get your feet off the pedals."
Reaction was not very friendly: "Captain of a C150 me thinks"
Or MCD wrote that application of "full rudder" was not the point.
Reading BOINGS post in this thread:
"The US airlines with whose training I am familiar have all been teaching inappropriate rudder use in upset recoveries for about five years. It did not start as excessive use of rudder. Initially the teaching was that an "appropriate" amount of rudder would be used to aid recovery. Over the years "appropriate" slowly evolved into "full" use of rudder. It was easy to see this transition take place sitting in the left hand seat during simulator check rides. My objections that excessive rudder was being used were ignored by the training system"
and following the nice informative post by PICKY PERKINS (thank you) I'm rather shocked that some forgotten oldfashioned pilot habits could have caused or contributed to this tragic accident.
411A in his charming manner is quite right: in big commercial airliners easy on the rudder.
BTW N380UA: when I was sitting LH on a A300-600 or A310 years ago recycling FAC CB (pull-push) to reengage pitch trim or YD was daily bread and butter routine. The FAC "needed" it sometimes.
Regards
Interesting.
Some contributions a bit far from reality, some more emotional
posts motivated more by sympathy for the poor crew or the company involved rather than dealing with facts. And than those brilliant tech. theories or explainations indicating profound system
knowledge and competence.(i.e. BELGIQUE, JOHN TULLAMARINE and others).
In a thread "witnesses saw AA 587 exlpode in flames" JAN2002
I wrote:
"I dare say during the next weeks the profs will circle again around those AA-Procedures you all heard about: the recovery out of unusual attitudes by applying full rudder. Believe me, the Airbus A 300-600 got a huge one and after takeoff you better get your feet off the pedals."
Reaction was not very friendly: "Captain of a C150 me thinks"
Or MCD wrote that application of "full rudder" was not the point.
Reading BOINGS post in this thread:
"The US airlines with whose training I am familiar have all been teaching inappropriate rudder use in upset recoveries for about five years. It did not start as excessive use of rudder. Initially the teaching was that an "appropriate" amount of rudder would be used to aid recovery. Over the years "appropriate" slowly evolved into "full" use of rudder. It was easy to see this transition take place sitting in the left hand seat during simulator check rides. My objections that excessive rudder was being used were ignored by the training system"
and following the nice informative post by PICKY PERKINS (thank you) I'm rather shocked that some forgotten oldfashioned pilot habits could have caused or contributed to this tragic accident.
411A in his charming manner is quite right: in big commercial airliners easy on the rudder.
BTW N380UA: when I was sitting LH on a A300-600 or A310 years ago recycling FAC CB (pull-push) to reengage pitch trim or YD was daily bread and butter routine. The FAC "needed" it sometimes.
Regards
Last edited by Captain104; 8th Nov 2002 at 18:02.
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Tree........
Accepted - the B737 hardover did not cause fins to fail but it did cause fatal crashes.
Boeing said "there is no problem" but published a recovery technique and then redesigned the rudder for the B737 NG - pretty telling for "no problem".
I am not saying Airbus are perfect or Boeing cr@p - just trying to point out the one-sided arguement. Why should european airliners be grounded if they have problems but American ones keep flying? Could we be talking bias here?
Any crash is a tragedy and should be investigated fully but the truth will only emerge if that investigation is both neutral and open minded. We learn from our errors and if carbon fibre tails are found to be inappropriate then action will be taken.
Concorde has been worked on and the problem sorted ou, the Comet was fixed (and still flies safely today as the RAF's Nimrod), Boeing have reworked their 737 PFCU and I expect that they will sort out the "exploding" fuel pumps, too.
I feel that there is a tendency to turn the blind eye to faults on American products if you live west of 30W - after all, Ford and Firestone said that the Explorer was fine!
Boeing said "there is no problem" but published a recovery technique and then redesigned the rudder for the B737 NG - pretty telling for "no problem".
I am not saying Airbus are perfect or Boeing cr@p - just trying to point out the one-sided arguement. Why should european airliners be grounded if they have problems but American ones keep flying? Could we be talking bias here?
Any crash is a tragedy and should be investigated fully but the truth will only emerge if that investigation is both neutral and open minded. We learn from our errors and if carbon fibre tails are found to be inappropriate then action will be taken.
Concorde has been worked on and the problem sorted ou, the Comet was fixed (and still flies safely today as the RAF's Nimrod), Boeing have reworked their 737 PFCU and I expect that they will sort out the "exploding" fuel pumps, too.
I feel that there is a tendency to turn the blind eye to faults on American products if you live west of 30W - after all, Ford and Firestone said that the Explorer was fine!
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So moggie,
Though boeing said no problem, they atleast did something. Airbus's reaction to the 737 crashes if they were airbus aircraft would simply be that its the pilot's fault.
Tell me what airbus has done? That is the problem. They just said, the pilot did it and there is nothing wrong with the plane and done NOTHING ELSE!
This is not a protectionism debate. I know that no airplane is perfect. However, it is airbus's position that no crash has been anything other than the pilot's fault. That is the problem that they refuse to address.
Airbus could fix the rudder load limiters fairly easily by either further limiting the rudder at high speeds (simply a software change, which would effectively prevent this from ever happeneing again) publishing limitations that are far more accurate than what is published now, or reducing the breakoutforce and or increasing the force to reach the stop at higher speeds (again a software change to reduce the chance of a Pilot Induced Oscilation).
You in your complaint against airbus bashing which you claim to be based on where you live ably pointed out the difference between the two companies. Boeing did something. Airbus did not, even though they knew about the problem atleast 4 years in advance.
Cheers
Wino
Though boeing said no problem, they atleast did something. Airbus's reaction to the 737 crashes if they were airbus aircraft would simply be that its the pilot's fault.
Tell me what airbus has done? That is the problem. They just said, the pilot did it and there is nothing wrong with the plane and done NOTHING ELSE!
This is not a protectionism debate. I know that no airplane is perfect. However, it is airbus's position that no crash has been anything other than the pilot's fault. That is the problem that they refuse to address.
Airbus could fix the rudder load limiters fairly easily by either further limiting the rudder at high speeds (simply a software change, which would effectively prevent this from ever happeneing again) publishing limitations that are far more accurate than what is published now, or reducing the breakoutforce and or increasing the force to reach the stop at higher speeds (again a software change to reduce the chance of a Pilot Induced Oscilation).
You in your complaint against airbus bashing which you claim to be based on where you live ably pointed out the difference between the two companies. Boeing did something. Airbus did not, even though they knew about the problem atleast 4 years in advance.
Cheers
Wino
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Are we learning something from this?
I am really disturbed by the practices described in anecdotal comments about recycling the breakers for YD, pitch/trim, FIC, etc. From these remarks, one can infer that this practice is common, normal, and sometimes considered necessary.
This may be a case where 'old-time' practices have been carried forward without much-needed examination for relevance and safety.
As a pilot, I am familiar with the decision process that leads to go/no-go decisions when some piece of MEL equipment is 'a bit flaky' but seems essentially sound: If you can inspire it to work in a perceptibly proper manner, you sure want to do that rather than scrub the flight. I am also very familiar with the tweaks and prodding sometimes required to fully awaken an aircraft from a cold / hot / long / damp sleep.
But as a computer architect, controls maven, and systems guy, it scares the stuffing out of me to think that repeatedly cycling primary power to mission critical systems - when the systems are balky on startup - is a popular cure-all in operations with "modern" aircraft.
The "modern" qualifier is meant to distinguish between older aircraft systems that were often controlled by relays and other mechanical contactors, versus newer ones that are principally implemented and controlled by electronic circuits of a much more complex nature. In the days of relays, cycling power repeatedly was a crude but effective way to break through oxides on the contacts and to free up stuck or slightly welded contacts on mechanical actuators.
In these modern days of electronics everywhere, cycling power a lot on systems is just a way to make them wear harder and fail much sooner than they otherwise would.
Not only that, the inability of an electronics-implemented control system to function *PERFECTLY* on the first power-up means either
a) it was designed wrong,
b) it (or something attached to it) is broken,
or c) both.
This is especially true for computer / microprocessor-driven systems - which most of the referenced ones appear to be.
If a system has to be recycled four times before it operates correctly, that really means the system probably is only working ok a mere ten percent of the time at initialization, (if I remember the statistics computation). Further correct operation is far from a sure thing. To emphasize the seriousness of this, one need note that initialization is, by design, normally the MOST reliable process in the operation of electronic control systems, so general operation may immediately be less reliable than the startup.
Tolerating faulty systems - in the aero controls especially - really introduces a wild card into the understanding of whatever happens afterward.
In what other aviation context would one *commence* flight with a critical system known to be working incorrectly more than half of the time ???? !!!!!!!! Not many, I hope.
Footnote: A practical procedure I would suggest, consistent with the above: If a system is not operating properly on power up, and smoke is not billowing forth, then leave power on awhile and give it an appropriate time to warm up. Then pull the breaker, count to 10, and repower it. If still inoperative, write it up, with bells.
I am really disturbed by the practices described in anecdotal comments about recycling the breakers for YD, pitch/trim, FIC, etc. From these remarks, one can infer that this practice is common, normal, and sometimes considered necessary.
This may be a case where 'old-time' practices have been carried forward without much-needed examination for relevance and safety.
As a pilot, I am familiar with the decision process that leads to go/no-go decisions when some piece of MEL equipment is 'a bit flaky' but seems essentially sound: If you can inspire it to work in a perceptibly proper manner, you sure want to do that rather than scrub the flight. I am also very familiar with the tweaks and prodding sometimes required to fully awaken an aircraft from a cold / hot / long / damp sleep.
But as a computer architect, controls maven, and systems guy, it scares the stuffing out of me to think that repeatedly cycling primary power to mission critical systems - when the systems are balky on startup - is a popular cure-all in operations with "modern" aircraft.
The "modern" qualifier is meant to distinguish between older aircraft systems that were often controlled by relays and other mechanical contactors, versus newer ones that are principally implemented and controlled by electronic circuits of a much more complex nature. In the days of relays, cycling power repeatedly was a crude but effective way to break through oxides on the contacts and to free up stuck or slightly welded contacts on mechanical actuators.
In these modern days of electronics everywhere, cycling power a lot on systems is just a way to make them wear harder and fail much sooner than they otherwise would.
Not only that, the inability of an electronics-implemented control system to function *PERFECTLY* on the first power-up means either
a) it was designed wrong,
b) it (or something attached to it) is broken,
or c) both.
This is especially true for computer / microprocessor-driven systems - which most of the referenced ones appear to be.
If a system has to be recycled four times before it operates correctly, that really means the system probably is only working ok a mere ten percent of the time at initialization, (if I remember the statistics computation). Further correct operation is far from a sure thing. To emphasize the seriousness of this, one need note that initialization is, by design, normally the MOST reliable process in the operation of electronic control systems, so general operation may immediately be less reliable than the startup.
Tolerating faulty systems - in the aero controls especially - really introduces a wild card into the understanding of whatever happens afterward.
In what other aviation context would one *commence* flight with a critical system known to be working incorrectly more than half of the time ???? !!!!!!!! Not many, I hope.
Footnote: A practical procedure I would suggest, consistent with the above: If a system is not operating properly on power up, and smoke is not billowing forth, then leave power on awhile and give it an appropriate time to warm up. Then pull the breaker, count to 10, and repower it. If still inoperative, write it up, with bells.
Last edited by arcniz; 7th Nov 2002 at 21:25.
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arcniz:
Your footnote-procedure sounds reasonable and proves common sense. That's what I was talking about. (plus or minus a second?) Agree with you completely:there is no sense in resetting a CB more than once and there are CB's in a modern Airbus or Boing I wouldn't touch without recommended by maintenance.
My remark above was referring to some speculation about AA 587 where the crew called maintenance due to disengaged YD/PT switches. They recycled FAC-CB prior leaving the ramp at JFK. All I meant was: probably nothing unusual, just routine.
BTW a FAC is not a FIC. A FAC is just a flight augmentation computer.
Your footnote-procedure sounds reasonable and proves common sense. That's what I was talking about. (plus or minus a second?)
Agree with you completely:there is no sense in resetting a CB more than once and there are CB's in a modern Airbus or Boing I wouldn't touch without recommended by maintenance. My remark above was referring to some speculation about AA 587 where the crew called maintenance due to disengaged YD/PT switches. They recycled FAC-CB prior leaving the ramp at JFK. All I meant was: probably nothing unusual, just routine.
BTW a FAC is not a FIC. A FAC is just a flight augmentation computer.
Last edited by Captain104; 8th Nov 2002 at 13:57.
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I strikes me, reading all the very many informative and relevant views that have now permiated this thread, that Airbus and Colin Chapman have alot in common.
The fact that Airbus have built a plane that can be mistreated to the point of destruction by the pilots by simply moving control surfaces in an inappropriate manner gives me the hebe gebbies! That just sounds absolutely rediculous. But I don't get this general feeling from this thread. Many of you seem to think that the pilot should not have used the rudder in such a way in the first place (not saying people are blaming the pilot...training issue). I say regardless of how the pilot flew the plane, it has been designed to carry 200 people over crowded densly populated areas. If a fin fails because of loading issues then that is a design problem pure and simple.
Is the A3X0 series just like a Lotus 49? Superbly equiped to do the job in-hand, extremely efficient but extremely fragile?
The fact that Airbus have built a plane that can be mistreated to the point of destruction by the pilots by simply moving control surfaces in an inappropriate manner gives me the hebe gebbies! That just sounds absolutely rediculous. But I don't get this general feeling from this thread. Many of you seem to think that the pilot should not have used the rudder in such a way in the first place (not saying people are blaming the pilot...training issue). I say regardless of how the pilot flew the plane, it has been designed to carry 200 people over crowded densly populated areas. If a fin fails because of loading issues then that is a design problem pure and simple.
Is the A3X0 series just like a Lotus 49? Superbly equiped to do the job in-hand, extremely efficient but extremely fragile?
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Wino
Quote: "Tell me what airbus has done? That is the problem. They just said, the pilot did it and there is nothing wrong with the plane and done NOTHING ELSE!"
I remember when my airline first introduced the 320. Airbus maintained that their aircraft was perfect. After many frustrating years Airbus finally started to listen to their customers and modified the arrogant manner in which they treated them. We all thought it was just the European (read French)way. But now they seem to have returned to their old ways.
The bottom line: A tiger doesn’t change its stripes
Quote: "Tell me what airbus has done? That is the problem. They just said, the pilot did it and there is nothing wrong with the plane and done NOTHING ELSE!"
I remember when my airline first introduced the 320. Airbus maintained that their aircraft was perfect. After many frustrating years Airbus finally started to listen to their customers and modified the arrogant manner in which they treated them. We all thought it was just the European (read French)way. But now they seem to have returned to their old ways.
The bottom line: A tiger doesn’t change its stripes
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Airbus may have their head in the sand - but Boeing did the same with the rudder and are still doing it with the fuel pumps. It too a lot of effort to get Boeing to fix the rudders (or even admit to the problem in the first place).
Maybe Airbus and Boeing are reluctant to admit problems if they are worried about getting their @rses sued off in the ludicrous American legal system. that is why Piper stopped producing aroplanes for some years - product liability litigation.
Maybe Airbus and Boeing are reluctant to admit problems if they are worried about getting their @rses sued off in the ludicrous American legal system. that is why Piper stopped producing aroplanes for some years - product liability litigation.
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Moggie!
You still don't get it. We could argue all day long about whether or not Beoing CHANGED the rudder fast enough, and it would be a valid arguement.
But what beoing did do, is as soon as the problem was documented they speeded up the approach speeds for the 737 so that a hard over would no longer mean a loss of the aircraft and published a procedure to deal with the failure. With the fuel pumps they again published a procedure to deal with the problem untill it could be fixed.
Airbus on the other hand has known for years that there is a problem with the A300 tail. They could have at the very least published a limitation, or a restriction on doublets. They did no such thing!
That is an absolute fact that you cannot dispute. And as a result 265 people are gone. Airbus did not make even the slightest effort. If you think boeing is poor, then by your standards airbus is worse! Your inability to see that makes you the biased protectionist one.
Cheers
WIno
You still don't get it. We could argue all day long about whether or not Beoing CHANGED the rudder fast enough, and it would be a valid arguement.
But what beoing did do, is as soon as the problem was documented they speeded up the approach speeds for the 737 so that a hard over would no longer mean a loss of the aircraft and published a procedure to deal with the failure. With the fuel pumps they again published a procedure to deal with the problem untill it could be fixed.
Airbus on the other hand has known for years that there is a problem with the A300 tail. They could have at the very least published a limitation, or a restriction on doublets. They did no such thing!
That is an absolute fact that you cannot dispute. And as a result 265 people are gone. Airbus did not make even the slightest effort. If you think boeing is poor, then by your standards airbus is worse! Your inability to see that makes you the biased protectionist one.
Cheers
WIno
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So then, IF some of the opinions here are more or less factual, Airboos has a lot to answer for.
Wonder IF they will face the music?...or, if the French have their collective way, all will be swept under the carpet.
Many concerned are waiting and watching.
One thing for sure, the lawyers will make a bundle.
Wonder IF they will face the music?...or, if the French have their collective way, all will be swept under the carpet.
Many concerned are waiting and watching.
One thing for sure, the lawyers will make a bundle.
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Interesting Observation
Curiously, as to the alleged excessive rudder inputs by the flying F/O: One AA captain had come out of the woodworks and testified to the NTSB that he remembered one particular incident when this F/O at an earlier time had applied multiple excessive rudder inputs while at the controls of a B727. This F/O was said to have rapidly cycled the rudders to nearly full deflection during one mild wake encounter at low altitude. The F/O had explained to this captain that his action was as per the AA "Advanced Maneuvering Program," ...whatever that may have said. The captain stated that he had vivid memories of this event as this was the only F/O who ever did this.
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Kefuddle_UK
Don't know if you're a pilot, but all of the commercial aircraft that I've flown COULD be mistreated to the point of destruction by "simply moving control surfaces in an inappropriate manner", hebe geebies or not.
That's why we learn pages of limitations for each type we fly and observe them if we wish to survive. Further limitations are imposed by safe flying practices and it is these which apply to the case in question.
I repeat the warning that anything other than small rudder inputs in co-ordination with aileron, when recovering from unusual attitudes, may lead to overstressing of the fin, certainly on ANY of the types that I've flown ( medium twin jets ).
IMHO
Don't know if you're a pilot, but all of the commercial aircraft that I've flown COULD be mistreated to the point of destruction by "simply moving control surfaces in an inappropriate manner", hebe geebies or not.
That's why we learn pages of limitations for each type we fly and observe them if we wish to survive. Further limitations are imposed by safe flying practices and it is these which apply to the case in question.
I repeat the warning that anything other than small rudder inputs in co-ordination with aileron, when recovering from unusual attitudes, may lead to overstressing of the fin, certainly on ANY of the types that I've flown ( medium twin jets ).
IMHO
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Glueball-
If that captain has memories of the right guy, that would be the biggest piece of news I've heard in this investigation. I wonder if he wrote up the incident at the time?
If that captain has memories of the right guy, that would be the biggest piece of news I've heard in this investigation. I wonder if he wrote up the incident at the time?
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I would think Glueball that if you want to post "a particular incident" involving one of the airman, that you get your facts completely correct, and if you cannot, then may I respectfully suggest you refrain from suggesting something based on an "alleged" story. IF there is anything to your allegation, it will most certainly be included in the NTSB findings.