He stepped on the Rudder and redefined Va
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Originally Posted by flarepilot
the FO did the correct thing on the first wake encounter...and did something different during the second...why would he?
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For the sake of argument
Originally Posted by NTSB
The Safety Board considered why the first officer responded differently to the second wake turbulence encounter than he did to the first encounter. One possibility is the difference in the bank angle at the beginning of the two encounters. For the first encounter, the airplane was approximately wings level. Before the second encounter, the airplane was already in a 23º left bank, and, according to the Board’s simulations, the rolling moment generated by the second wake would have acted to roll the airplane (in the absence of countering control inputs) about 10º farther to the left and would have resulted in no significant yaw. However, if the first officer sensed a roll acceleration to the left while already in a left bank, he may have been prompted to react with a more aggressive control response.
The Safety Board emphasizes that the second wake encounter did not place flight 587 in an upset condition, and the airplane’s response to the wake did not indicate that an upset was imminent.197 Therefore, the Safety Board concludes that the first officer’s initial control wheel input in response to the second wake turbulence encounter was too aggressive, and his initial rudder pedal input response was unnecessary to control the airplane.
The Safety Board emphasizes that the second wake encounter did not place flight 587 in an upset condition, and the airplane’s response to the wake did not indicate that an upset was imminent.197 Therefore, the Safety Board concludes that the first officer’s initial control wheel input in response to the second wake turbulence encounter was too aggressive, and his initial rudder pedal input response was unnecessary to control the airplane.
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That question has been asked so many times on this thread that I'm wondering if anyone has read the NTSB's report. It discusses that very question in some detail and provides an explanation that satisfies me.
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Dozy,
you omit the link to training exercises presented as a wake encounter, where the simulator was manipulated so that it did not respond to pilot inputs while the simulated airplane banked to 90 degrees.
you omit the link to training exercises presented as a wake encounter, where the simulator was manipulated so that it did not respond to pilot inputs while the simulated airplane banked to 90 degrees.
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For those that want to read the report in full:
http://www.ntsb.gov/doclib/reports/2004/AAR0404.pdf
Last edited by DozyWannabe; 4th Oct 2013 at 23:26.
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The Safety Board considered why the first officer responded differently to the second wake turbulence encounter than he did to the first encounter. One possibility is the difference in the bank angle at the beginning of the two encounters. For the first encounter, the airplane was approximately wings level. Before the second encounter, the airplane was already in a 23º left bank, and, according to the Board’s simulations, the rolling moment generated by the second wake would have acted to roll the airplane (in the absence of countering control inputs) about 10º farther to the left and would have resulted in no significant yaw. However, if the first officer sensed a roll acceleration to the left while already in a left bank, he may have been prompted to react with a more aggressive control response.
The Safety Board emphasizes that the second wake encounter did not place flight 587 in an upset condition, and the airplane’s response to the wake did not indicate that an upset was imminent.197 Therefore, the Safety Board concludes that the first officer’s initial control wheel input in response to the second wake turbulence encounter was too aggressive, and his initial rudder pedal input response was unnecessary to control the airplane.
The Safety Board emphasizes that the second wake encounter did not place flight 587 in an upset condition, and the airplane’s response to the wake did not indicate that an upset was imminent.197 Therefore, the Safety Board concludes that the first officer’s initial control wheel input in response to the second wake turbulence encounter was too aggressive, and his initial rudder pedal input response was unnecessary to control the airplane.
Of course, I certainly entertain the logic of a momentary on-set acceleration being immediately noticed PRIOR to the airplane actually beginning to move (and thereby NOT recorded on the FDR) and have that on-set acceleration recognition prompt the pilot to apply substantial right control wheel deflection simultaneously with substantial right rudder input – BEFORE that acceleration actually produced an FDR-recorded rolling movement. In fact, I think that such razor-thin timing is very likely what actually happened … but I also think that would result from one of only two sets of circumstances:
First – this pilot was always reacting almost before anyone else recognized the need for any reaction – and in my experience that almost never occurs; and
Second – the F/O was bordering on or had reached a panicked mental state.
Unfortunately, THAT I have seen … and believe me, if you’ve ever seen it, you will always remember it! In fact, I think it is entirely possible that the Captain had either noticed or suspicioned something being inconsistent with what he had previously seen from that F/O and that was why he asked “Are you all right?” pretty much AS the F/O applied those extreme control inputs and said “Let’s go for power please.” I think it’s also important to note that the F/O comment on power was annotated as being spoken in “a strained voice” – also a reaction to panic.
Apparently, the F/O continued to apply these substantial control inputs – very likely after the first such input, were made thinking they were necessary to counter what the airplane was doing … and the airplane was merely doing what it was commanded to do by the F/O control inputs.
Again, I take no particular joy in making these comments – but I think it’s a logical way to make all the pieces of the facts make some kind of sense.
OK – I’m ready for the critiques.
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Owain, thanks for the pedal vs rudder deflection chart. I have never seen it. I am sure there is no reverse input from the rudders to the pedals so if the graph is correct the inputs were made from the cockpit. I just don't understand why. I don't feel AA pilots can not make mistakes because of the numerous ones in our history. I just feel we need to defend our pilots when there is a question about what input they had in a crash. I feel the same way about other airlines having a crash and blaming the crew. I always try to defend my crew until it is obvious they screwed up. I hope we all do.
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NTSB Press Release
National Transportation Safety Board
Office of Public Affairs
________________________________________
NTSB SAYS PILOT'S EXCESSIVE RUDDER PEDAL INPUTS LED TO CRASH OF AMERICAN FLIGHT 587; AIRBUS RUDDER SYSTEM DESIGN & ELEMENTS OF AIRLINE'S PILOT TRAINING PROGRAM CONTRIBUTED
OCTOBER 26, 2004
Washington, D.C. - American Airlines flight 587 crashed into a Queens neighborhood because the plane's vertical stabilizer separated in flight as a result of aerodynamic loads that were created by the first officer's unnecessary and excessive rudder pedal inputs after the aircraft encountered wake turbulence, according to a final report adopted by the National Transportation Safety Board today. The Board said that contributing to the crash were characteristics of the airplane's rudder system design and elements of the airline's pilot training program.
At about 9:16 a.m. on November 12, 2001, flight 587, an Airbus A300-605R (N14053), crashed in Belle Harbor, New York shortly after taking off from John F. Kennedy International Airport on a flight to Santo Domingo. All 260 people aboard the plane died, as did five persons on the ground. This is the second deadliest aviation accident in American history.
The aircraft's vertical stabilizer and rudder were found in Jamaica Bay, about a mile from the main wreckage site. The engines, which also separated from the aircraft seconds before ground impact, were found several blocks from the wreckage site. The Safety Board found that the first officer, who was the flying pilot, inappropriately manipulated the rudder back and forth several times after the airplane encountered the wake vortex of a preceding Boeing 747 for the second time. due to The aerodynamic loads placed on the vertical stabilizer he sideslip that resulted from the rudder movements were beyond the ultimate design strength of the vertical stabilizer. (Simply stated, sideslip is a measure of the "sideways" motion of the airplane through the air.)
The Board found that the composite material used in constructing the vertical stabilizer was not a factor in the accident because the tail failed well beyond its certificated and design limits.
The Safety Board said that, although other pilots provided generally positive comments about the first officer's abilities, two pilots noted incidents that showed that he had a tendency to overreact to wake turbulence encounters. His use of the rudder was not an appropriate response to the turbulence, which in itself provided no danger to the stability of the aircraft, the Board found.
The Board said that American Airlines' Advanced Aircraft Maneuvering Program contributed to the accident by providing an unrealistic and exaggerated view of the effects of wake turbulence on heavy transport-category aircraft. In addition, the Board found that because of its high sensitivity, the A300-600 rudder control system is susceptible to potentially hazardous rudder pedal inputs at higher speeds. In particular, the Board concluded that, before the crash of flight 587, pilots were not being adequately trained on what effect rudder pedal inputs have on the A300- 600 at high airspeeds, and how the airplane's rudder travel limiter system operates.
The Safety Board's airplane performance study showed that the high loads that eventually overstressed the vertical stabilizer were solely the result of the pilot's rudder pedal inputs and were not associated with the wake turbulence. In fact, had the first officer stopped making inputs at any time before the vertical stabilizer failed, the natural stability of the aircraft would have returned the sideslip angle to near 0 degrees, and the accident would not have happened. (The Board estimated that the sideslip angle at the time the vertical stabilizer separated was between 10 and 12.5 degrees.)
The NTSB issued eight recommendations in today's report. Among the seven sent to the Federal Aviation Administration were those calling for adopting certification standards for rudder pedal sensitivity, modifying the A300- 600 and A310 rudder control systems to increase protection from potentially hazardous rudder pedal inputs at high speeds (a similar recommendation was issued to the French equivalent of the FAA, the DGAC), and publishing guidance for airline pilot training programs to avoid the kind of negative training found in American Airlines' upset recovery training.
Because this crash occurred two months after the September 11 terrorist attacks, there was initial concern that it might have been the result of an intentional criminal act. The Board found no such evidence, nor did any law enforcement agencies provide evidence that the accident may have stemmed from criminal conduct. The Board said that witnesses who reported observing the airplane on fire were most likely observing misting fuel released from broken fuel lines, a fire from the initial release of fuel or the effects of engine compressor surges.
A summary of the Board's report may be found under "Publications" on the agency's website at NTSB - National Transportation Safety Board. The full report will appear on the website in about four weeks.
National Transportation Safety Board
Office of Public Affairs
________________________________________
NTSB SAYS PILOT'S EXCESSIVE RUDDER PEDAL INPUTS LED TO CRASH OF AMERICAN FLIGHT 587; AIRBUS RUDDER SYSTEM DESIGN & ELEMENTS OF AIRLINE'S PILOT TRAINING PROGRAM CONTRIBUTED
OCTOBER 26, 2004
Washington, D.C. - American Airlines flight 587 crashed into a Queens neighborhood because the plane's vertical stabilizer separated in flight as a result of aerodynamic loads that were created by the first officer's unnecessary and excessive rudder pedal inputs after the aircraft encountered wake turbulence, according to a final report adopted by the National Transportation Safety Board today. The Board said that contributing to the crash were characteristics of the airplane's rudder system design and elements of the airline's pilot training program.
At about 9:16 a.m. on November 12, 2001, flight 587, an Airbus A300-605R (N14053), crashed in Belle Harbor, New York shortly after taking off from John F. Kennedy International Airport on a flight to Santo Domingo. All 260 people aboard the plane died, as did five persons on the ground. This is the second deadliest aviation accident in American history.
The aircraft's vertical stabilizer and rudder were found in Jamaica Bay, about a mile from the main wreckage site. The engines, which also separated from the aircraft seconds before ground impact, were found several blocks from the wreckage site. The Safety Board found that the first officer, who was the flying pilot, inappropriately manipulated the rudder back and forth several times after the airplane encountered the wake vortex of a preceding Boeing 747 for the second time. due to The aerodynamic loads placed on the vertical stabilizer he sideslip that resulted from the rudder movements were beyond the ultimate design strength of the vertical stabilizer. (Simply stated, sideslip is a measure of the "sideways" motion of the airplane through the air.)
The Board found that the composite material used in constructing the vertical stabilizer was not a factor in the accident because the tail failed well beyond its certificated and design limits.
The Safety Board said that, although other pilots provided generally positive comments about the first officer's abilities, two pilots noted incidents that showed that he had a tendency to overreact to wake turbulence encounters. His use of the rudder was not an appropriate response to the turbulence, which in itself provided no danger to the stability of the aircraft, the Board found.
The Board said that American Airlines' Advanced Aircraft Maneuvering Program contributed to the accident by providing an unrealistic and exaggerated view of the effects of wake turbulence on heavy transport-category aircraft. In addition, the Board found that because of its high sensitivity, the A300-600 rudder control system is susceptible to potentially hazardous rudder pedal inputs at higher speeds. In particular, the Board concluded that, before the crash of flight 587, pilots were not being adequately trained on what effect rudder pedal inputs have on the A300- 600 at high airspeeds, and how the airplane's rudder travel limiter system operates.
The Safety Board's airplane performance study showed that the high loads that eventually overstressed the vertical stabilizer were solely the result of the pilot's rudder pedal inputs and were not associated with the wake turbulence. In fact, had the first officer stopped making inputs at any time before the vertical stabilizer failed, the natural stability of the aircraft would have returned the sideslip angle to near 0 degrees, and the accident would not have happened. (The Board estimated that the sideslip angle at the time the vertical stabilizer separated was between 10 and 12.5 degrees.)
The NTSB issued eight recommendations in today's report. Among the seven sent to the Federal Aviation Administration were those calling for adopting certification standards for rudder pedal sensitivity, modifying the A300- 600 and A310 rudder control systems to increase protection from potentially hazardous rudder pedal inputs at high speeds (a similar recommendation was issued to the French equivalent of the FAA, the DGAC), and publishing guidance for airline pilot training programs to avoid the kind of negative training found in American Airlines' upset recovery training.
Because this crash occurred two months after the September 11 terrorist attacks, there was initial concern that it might have been the result of an intentional criminal act. The Board found no such evidence, nor did any law enforcement agencies provide evidence that the accident may have stemmed from criminal conduct. The Board said that witnesses who reported observing the airplane on fire were most likely observing misting fuel released from broken fuel lines, a fire from the initial release of fuel or the effects of engine compressor surges.
A summary of the Board's report may be found under "Publications" on the agency's website at NTSB - National Transportation Safety Board. The full report will appear on the website in about four weeks.
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Yup, I remember that discussion. As I recall it related to the "variable stop" rudder pedal limiting system as used on the A300-600. For the record, the same system is used on the DC-8 and DC-9/MD-80-90 series.
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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".
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you omit the link to training exercises presented as a wake encounter, where the simulator was manipulated so that it did not respond to pilot inputs while the simulated airplane banked to 90 degrees.
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Sounds like good training to me. I did similar things teaching basic students. JFK JR could have used another session before his crash. I think we have all had vertigo. Training lets us overcome it. It saved my butt once.
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Doesn't matter if it behaves differently, it's still the same system.
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Oops, the first rudder input did a huge amount of yaw, better bring it back. Oops went too far the other way with these small pedal inputs that have a large effect. Damn, I am overcontrolling it, good thing we are relatively slow. CRACK.
Meanwhile, the captain assumed that it was bad wake turbulence from that heavily loaded 747.
Only a guess of course.
Last edited by JammedStab; 5th Oct 2013 at 01:27.
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A300-600 is variable stop....high breakout....and with nearly linear variation in pedal force versus deflection.
A300-600R has a light breakout force.
APA submission to the NTSB, page 8 -
http://alliedpilots.org/Public/Topic...submission.pdf
The change in maximum force and degrees of rudder per pound between the A300B2/B4
and the A300-600 is highly significant. The A300 family (should say A300-600R. Look at chart on page 8) has the distinction of having the
lightest breakout force and the highest number of degrees of rudder travel per pound of
force of any other transport category aircraft. Once a pilot initiates rudder movement, he
or she will be challenged with the most sensitive rudder handling qualities of any
transport category airplane. This sensitivity is a precursor to a characteristic known as
Aircraft Pilot Coupling (APC), a condition typically “…not feasible for a pilot to realize
and react to in real time,” and considered unacceptable in U.S. certified designs
(National Research Council 15). Simply, a very light application of force coupled with a
very small movement of the rudder pedal will yield full deflection of the rudder.
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Is the rudder pedal force sensitivity that much of an issue when a pilot pushes the pedal to the stop with a force of 140 lbs?
Last edited by HazelNuts39; 5th Oct 2013 at 07:05.
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"BE GENTLE WITH ME, HENRY!!!!"
Have I missed something during the long transition from mil to civil aviation?
Or possibly neurons dissolved by too much sleeping lotion has erased the memory?
As far back as I can recall, rudder use in swept-wing aircraft was a delicate subject, as was the teaching of its use on the same 'frames.
On the Gnat Advanced training course in the RAF, we were given ONE demo of its use and effects at high altitude (to allow for the subsequent recovery if needed!) and that was it. Yes, squeeze it to remove drift before X-wind touchdown, but no more. The skin of the fin was cutaway on those 'frames with cracks in the attachment brackets, so we could compare them during walkaround, having "memorised" the crack shape and extent as we signed out the tech log in the line hut. Any noticeable discrepancy and it was back to the hut for another, please?!
This was as a result of fatalities due to fin separation in previous accidents as the phenominal rate of roll of that aircraft was the perceived cause of the early fatigueing.
Now it appears from the A300 accident that coarse and assertive rudder use was at one time being trained as an upset recovery technique. Where did the disconnect intrude into the mind of those who thought this was an acceptable and beneficial method of regaining control of a swept-wing public transport medium to heavy aircraft?
Forward the tape to the 90s and the recommendation from Mr Boeing that the full&free rudder check on the 747 should take 2 seconds from neutral to full deflection, both ways, and avoid crashing the rudders against the stops with coarse inputs.
This was apparently introduced as the routine inspections luckily discovered the PFCU attachment brackets were cracking as the barn doors on the 747 VS assembly were being crashed from side to side against the stops by the inadequately trained gorillas then operating them.
Fast forward the tape (yes I know, VHS-speak!) to today, and observe the massive rudder on the 73NG being slammed against the stops by the current crop of Captains, and if you don't see it from outside, then try sitting in the seats in the aft row and FEEL and HEAR the clunk as they hit the stops.
It gives me the chills when I feel it, and I am forced to ask what are the type-rating trainers and the line trainers up to by allowing this crass, clumsy and careless handling?
It all goes to show that there are some lessons in this game which we have forgotten, at our peril, when it comes to having respect for the flying controls and their effectiveness.
Are there any NG engineers out there who can reassure me the NG rudder assembly is NOT suffering from this abuse so that I'll sleep easier?
Or possibly neurons dissolved by too much sleeping lotion has erased the memory?
As far back as I can recall, rudder use in swept-wing aircraft was a delicate subject, as was the teaching of its use on the same 'frames.
On the Gnat Advanced training course in the RAF, we were given ONE demo of its use and effects at high altitude (to allow for the subsequent recovery if needed!) and that was it. Yes, squeeze it to remove drift before X-wind touchdown, but no more. The skin of the fin was cutaway on those 'frames with cracks in the attachment brackets, so we could compare them during walkaround, having "memorised" the crack shape and extent as we signed out the tech log in the line hut. Any noticeable discrepancy and it was back to the hut for another, please?!
This was as a result of fatalities due to fin separation in previous accidents as the phenominal rate of roll of that aircraft was the perceived cause of the early fatigueing.
Now it appears from the A300 accident that coarse and assertive rudder use was at one time being trained as an upset recovery technique. Where did the disconnect intrude into the mind of those who thought this was an acceptable and beneficial method of regaining control of a swept-wing public transport medium to heavy aircraft?
Forward the tape to the 90s and the recommendation from Mr Boeing that the full&free rudder check on the 747 should take 2 seconds from neutral to full deflection, both ways, and avoid crashing the rudders against the stops with coarse inputs.
This was apparently introduced as the routine inspections luckily discovered the PFCU attachment brackets were cracking as the barn doors on the 747 VS assembly were being crashed from side to side against the stops by the inadequately trained gorillas then operating them.
Fast forward the tape (yes I know, VHS-speak!) to today, and observe the massive rudder on the 73NG being slammed against the stops by the current crop of Captains, and if you don't see it from outside, then try sitting in the seats in the aft row and FEEL and HEAR the clunk as they hit the stops.
It gives me the chills when I feel it, and I am forced to ask what are the type-rating trainers and the line trainers up to by allowing this crass, clumsy and careless handling?
It all goes to show that there are some lessons in this game which we have forgotten, at our peril, when it comes to having respect for the flying controls and their effectiveness.
Are there any NG engineers out there who can reassure me the NG rudder assembly is NOT suffering from this abuse so that I'll sleep easier?
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Originally Posted by [URL=http://alliedpilots.org/Public/Topic...submission.pdf
[...] certification “loophole” [...]
Thank you misd-agin
Did the other aeronautical agencies try to copy ?
Originally Posted by BARKINGMAD
Fast forward the tape (yes I know, VHS-speak!) to today, and observe the massive rudder on the 73NG being slammed against the stops by the current crop of Captains, and if you don't see it from outside, then try sitting in the seats in the aft row and FEEL and HEAR the clunk as they hit the stops.
It gives me the chills when I feel it, and I am forced to ask what are the type-rating trainers and the line trainers up to by allowing this crass, clumsy and careless handling?
It all goes to show that there are some lessons in this game which we have forgotten, at our peril, when it comes to having respect for the flying controls and their effectiveness.
Are there any NG engineers out there who can reassure me the NG rudder assembly is NOT suffering from this abuse so that I'll sleep easier?
It gives me the chills when I feel it, and I am forced to ask what are the type-rating trainers and the line trainers up to by allowing this crass, clumsy and careless handling?
It all goes to show that there are some lessons in this game which we have forgotten, at our peril, when it comes to having respect for the flying controls and their effectiveness.
Are there any NG engineers out there who can reassure me the NG rudder assembly is NOT suffering from this abuse so that I'll sleep easier?