Interesting note about AA Airbus crash in NYC

[AirRabbit]

Originally Posted by Casper

Has it been officially proved (and beyond doubt) that rudder hardover was a factor in Colorado Springs and Pittsburgh?

As far as I know, the answer to your question is "no." However, the circumstances do point, quite heavily, toward rudder involvement.

The significant point, however, does not necessarily stop at understanding the rudder implications. In both of these cases, the crew was at a relatively slow airspeed and the indications were that they tried to slow even further. There is a phenomenon called "cross-over speed" that comes into play in circumstances such as these. This is where, at a given speed, the rudder and the ailerons are equally effective in controlling the roll of the airplane. Below that speed, the rudder becomes even more effective in that control. Above that speed, the ailerons become more effective. In both of these cases, there is a reasonable likelihood that, had the crew accelerated to something above that "cross-over" speed, they would have been able to recover, even WITH the existing rudder problem thought to exist.

[Casper]

Thanks, AirRabbit. That is interesting info. Boeing "suggested" that the amendment to the B737 QRH re rudder problems was effected due to "politics."

I was also under the impression that some local weather factor (mountain waves) may have contributed to the Colorado Springs accident.

[bomarc]

casper

as the builder of the part of the rudder actuator has taken the lion's share of the liability in the pittsburgh crash, and that the FAA has mandated that there be a "fix" to the rudder problem ( in this case a radio altimeter input to reduce hydraulic pressure to the rudder above 700'agl) I think that we can gather that the rudder was the problem.

as to mountain wave in the colorado springs tragedy, it is up to you to decide for yourself.

I've decided that the rudder is a POS

[AirRabbit]

Originally Posted by bomarc

as the builder of the part of the rudder actuator has taken the lion's share of the liability in the pittsburgh crash, and that the FAA has mandated that there be a "fix" to the rudder problem ( in this case a radio altimeter input to reduce hydraulic pressure to the rudder above 700'agl) I think that we can gather that the rudder was the problem.

Yes, the rudder pressue is reduced to about half - unless there is an engine problem during takeoff. If that happens, the reduction does not occur. But as for "gathering that the rudder was the problem," that may be going just a bit far. Here is link to an FAA document that was published approximately 6 years ago. The contents of this FAA Bulletin contain a lot more of the detail in what was decided and how the facts were going to be dealt with regarding the B-737 "rudder issues." You can judge for yourself.
http://www.faa.gov/library/manuals/e...a/Fsga0009.doc

Originally Posted by bomarc

as to mountain wave in the colorado springs tragedy, it is up to you to decide for yourself.

I'd go along with that recommendation.

Originally Posted by bomarc

I've decided that the rudder is a POS

I'm sure we're all glad to know of your decision.

[JustAnothrWindScreen]

Originally Posted by AirRabbit

2) The entire episode, from the first controller movement to the end of the data feed was just under 9 seconds in duration. To say that the Captain, or anyone else for that matter, should have been able to observe what was happening, evaluate the cause, determine what was being responded to and how, recognize the adequacy or inadequacy of what was being done, decide on a course of action, and initiate that course of action - and do all that cold, with zero warning, and do it all successfully - is a mighty tall order for a mere human to grasp. I might point out that it probably took you 7 or 8 seconds to read that last sentence.

Thats what airline Captains do all the time and is not a tall order for a mere human. When you look at your watch, 9 seconds is an eternity.

[Rainboe]

Yes, but the point seems to be missed that during a sudden violent distraction, such as a serious wake encounter, it is perhaps understandable if the Captain's attention is distracted for a short time away from what is happening hidden from view in front of the control column His feet wouldn't be riding the rudder pedals as the copilot was flying, so there would be no tactile feedback.

[DozyWannabe]

Originally Posted by Casper

Thanks, AirRabbit. That is interesting info. Boeing "suggested" that the amendment to the B737 QRH re rudder problems was effected due to "politics."

They also spent a considerable amount of money coming up with their own report saying that the crashes were both likely to be a result of pilot input rather than a design fault with the rudder system - aren't corporate lawyers great?

I was also under the impression that some local weather factor (mountain waves) may have contributed to the Colorado Springs accident.

It's plausible, but I'd have thought that a strong mountain rotor would have caused a mid-air breakup as with the BOAC 707 Mt. Fuji incident, rather than forcing the aircraft into the ground intact as happened in Colorado Springs.

Pointless speculation here, but the problem was with the PCU, which could jam and send the rudder into a hardover in the opposite direction to that commanded by the pilot. I've wondered for a while whether both those aircraft encountered some kind of turbulent air and when the rudder was used to correct, the PCU jammed and this 'reverse hardover' defect came into play.

Either way we're drifting off topic, although it's useful to note that no manufacturer is happy about admitting their arcraft has a fault.

[Graybeard]

Originally Posted by Rainboe

Yes, but the point seems to be missed that during a sudden violent distraction, such as a serious wake encounter, it is perhaps understandable if the Captain's attention is distracted for a short time away from what is happening hidden from view in front of the control column His feet wouldn't be riding the rudder pedals as the copilot was flying, so there would be no tactile feedback.

Tactile feedback was in his butt.

GB

[bomarc]

air rabbit

if the rudder wasn't the problem on the 737 pit and cos, then:

why is there so much training in rudder hardover recovery for this plane?

why are there now memory items for turning off the hydraulic power to the rudder?

why is there a pressure reduction mechanism?

why are crossover speeds so vital a part in flying the plane now?


believe me, it is much easier a plane to fly with the old "speeds", (except for the lack of rudder hardover protection)
=================================================

I know people who actually believe that both crashes were completely pilot error.

Perhaps these are the same kind of people also would blame the pilots for the electra crashes in the 50's.
----------------------------------------------------------------

and yes to the chap who mentioned corporate lawyers! they do earn their money.

I went to the NTSB hearing in the DC area (near the springfield shopping mall for those familiar with the area).


One thing that did come out was that more recent standards of certification would indicate that the 737 in its present form would not have been certified.


Could this concept be useful with the airbus 300?

[barit1]

Nor could the DC-3, in original or present form, be certified. This proves nothing except that cert stds change from time to time. Does this surprise anyone?

[AirRabbit]

Originally Posted by JustAnothrWindScreen

Thats what airline Captains do all the time and is not a tall order for a mere human. When you look at your watch, 9 seconds is an eternity.

Without trying to be overly critical of your opinion, I think that all of us would like to believe our own “press:” Supermen (and women), highly trained, laser-like mind, inerrantly finding the problem and whipping out a weird, but effective, solution. Would that it were so … but James Bond is still a fictional character.

Your characterization of 9 seconds being an eternity is, as I’m sure you recognize, a relative perception. Pointing up that relation is a pretty “standard” attorney response when a witness says “I only got a very brief view of the murder – only about 9 seconds.” The attorney calmly asks the jury to see how long 9 seconds really are … “Ladies and gentlemen, I’m going to ask you to hold your breath when I say ‘now’ and to hold it until I say ‘ok’ at the 9 second mark, and we’ll see just how long 9 seconds really is.” As Einstein once described, “When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity.” The timing involved here is just as “relative.”

If you look at the animation of the FDR, the first couple of control applications and reversals (time marker 15:51 through 15:54) probably didn’t get the airplane terribly “out-of-sorts” with itself – at least to the point that the Captain would have immediately suspected the F/O was about to tear the tail off the airplane – and that is why the Captain asked “You alright?” in response to the F/O’s request for “max power;” which was said some 3 seconds into the “less than 9-second” ordeal. Again, view the animation of the position of the airplane during this brief period. Note how far the airplane animation actually moves. In calm air, this movement would probably be noticeable; but having just experienced an encounter with a wing-tip vortex, I don’t think the second encounter was a surprise – and certainly not one of ominous proportions. However, it is more than likely that, even without an immediately recognizable “tactile impression” of danger in the cockpit (despite Graybeard’s comment, “Tactile feedback was in his butt"), the damage was probably already begun.

The next couple of control inputs and reversals probably DID get the attention of the Captain, but the response of the F/O, “Yeah, I’m fine” would have likely given the Captain reason to pause in his judgment, and additionally, the Captain was very likely evaluating and/or attempting to comply with the F/O’s request for “max power.” Immediately thereafter, he was either directing or encouraging the F/O with his comment “hang on to it, hang on to it.” It was at that moment that the airplane started a rather sizable yaw moment to the left – and there is very little doubt that the Captain would have missed that movement – however, I think THAT was the final straw, and the vertical stab departed the airplane. The time markers between those points are 15:57 and 15:59 – after which the data feed stops.

The Captain was not sitting in isolation, pre-loaded to see, recognize, and respond to a problem – particularly one of the magnitude that was developing. He observed and challenged; and he got what was likely determined to be a reasonable response. But from there it went down hill with the burners full on! I am as sure as I can be that these guys did not feel this scenario was unfolding over some lengthy time period.

Originally Posted by DozyWannabe

They also spent a considerable amount of money coming up with their own report saying that the crashes were both likely to be a result of pilot input rather than a design fault with the rudder system - aren't corporate lawyers great? .

Yes, this is true; but would you expected to have Boeing, or anyone else for that matter, say, “Yep. Guilty. We’ve built the world’s most unsafe airplane.” I suspect that they were trying to walk the very fine line between telling the unbridled truth and perhaps scuttling the company; and out-right lying by claiming that there isn’t, and could not be, anything wrong with the airplane. I don’t believe either of those two extreme positions were accurate. It may well be that the engineers at Boeing don’t even know for sure, what the no-sh*t reason was behind those crashes. However, that the rudder was involved in some way is very hard to argue against. But, if you don’t know (or can’t admit) how do you address the situation?

Originally Posted by DozyWannabe

Pointless speculation here, but the problem was with the PCU, which could jam and send the rudder into a hardover in the opposite direction to that commanded by the pilot. I've wondered for a while whether both those aircraft encountered some kind of turbulent air and when the rudder was used to correct, the PCU jammed and this 'reverse hardover' defect came into play. .

I suspect that laying the responsibility on the PCU was a reasonable route to follow. Was it the REAL cause? I don’t know. My guess is that Boeing would say that it was prudent to re-address the rudder control issues from top to bottom, including the PCU. In fact, I think that is exactly what they DID say – or something close to that.

Originally Posted by DozyWannabe

Either way we're drifting off topic, although it's useful to note that no manufacturer is happy about admitting their arcraft has a fault.

My point as well.

Originally Posted by bomarc

air rabbit
if the rudder wasn't the problem on the 737 pit and cos, then:
why is there so much training in rudder hardover recovery for this plane?

To my knowledge, the training received by pilots flying the B-737 (all series) in addition to the systems taught in ground school, has to do with “cross-over” speeds – where slower airspeeds allow the rudder to be more effective at controlling roll and higher speeds allow the ailerons to be more effective at controlling roll. Therefore, if you have a rudder/roll problem, accelerate to above the cross-over speed to be able to control the roll with the roll control for the airplane, the ailerons.

why are there now memory items for turning off the hydraulic power to the rudder?

Because it makes good sense. If there is any possibility that a powered rudder is causing or exacerbating an existing problem, it would be prudent to eliminate the powered rudder input.

why is there a pressure reduction mechanism?

Because it makes good sense. Even if the existence of a powered rudder had nothing to do with the accidents, it would be good press to take the extra steps to include a rudder pressure reduction system – and, it would be like chicken soup – it couldn’t hurt – particularly if the system prevents pressure reduction in those cases where having the rudder powered is a good thing – like on an engine failure during takeoff.

why are crossover speeds so vital a part in flying the plane now?

I don’t think that cross-over speeds are any more vital now than they used to be. It’s just that more people are more aware of what they are, what they mean, and how that knowledge may be able to save your butt.

believe me, it is much easier a plane to fly with the old "speeds", (except for the lack of rudder hardover protection)

Well, I’m not terribly sure about that. I fly the B-737 and it’s like any other change made to an airplane. IF you were aware of what cross-over speeds were, how they affected the handling characteristics of the B-737 (or any other airplane for that matter), and used that knowledge if or when necessary, I’m not sure that a so-called “rudder hardover” would be a problem.

Originally Posted by bomarc

I know people who actually believe that both crashes were completely pilot error. Perhaps these are the same kind of people also would blame the pilots for the electra crashes in the 50's.

Yes, I’m sure that is true. There are also people who believe that it was a Tomahawk missile that crashed into the Pentagon on 9/11. There are others believe that extraterrestrial aliens are roaming the streets of Roswell, New Mexico. Maybe they should all get together and have a picnic?

Originally Posted by bomarc

and yes to the chap who mentioned corporate lawyers! they do earn their money.

Sometimes they do. Sometimes they don’t.

Originally Posted by bomarc

I went to the NTSB hearing in the DC area (near the springfield shopping mall for those familiar with the area). One thing that did come out was that more recent standards of certification would indicate that the 737 in its present form would not have been certified. Could this concept be useful with the airbus 300?

Are you saying that the “new” certification standards would not allow for the B-737NG to be certificated? And, I’m sure you’re aware that current standards wouldn’t allow many airplanes still flying to be certificated either. So, what would be your recommendation? Ground them all?

[DozyWannabe]

Originally Posted by AirRabbit

Yes, this is true; but would you expected to have Boeing, or anyone else for that matter, say, “Yep. Guilty. We’ve built the world’s most unsafe airplane.” ... But, if you don’t know (or can’t admit) how do you address the situation?

You're absolutely correct sir. As I stated below, I don't think any manufacturer would do that, and in fact it would probably have a negative impact of safety were the company to be scuttled rather than a fix found.

I just mentioned it to counteract the opinions of those who think that kind of behaviour is strictly a French or Airbus thing.

I suspect that laying the responsibility on the PCU was a reasonable route to follow. Was it the REAL cause? I don’t know. My guess is that Boeing would say that it was prudent to re-address the rudder control issues from top to bottom, including the PCU. In fact, I think that is exactly what they DID say – or something close to that.

Correct again. I've never disagreed with the PCU being the primary failure point. My speculation was purely on the basis of the PCU failing during an attempt to recover what was up until then a normal weather or wake encounter. The Seattle Times report suggested that Boeing may have known that there was something not quite right with the setup when a 747 elevator assembly (using the same or similar components) was reported as misbehaving some time before the 737 accidents occurred.

It just depresses me when I read things like 'What A French POS' regardless of the source, simply because while such statements are obviously provocative rather than helpful, it means that out there, someone does believe that to be the case. For all talk of lack of robustness, the only airliner to survive a missile strike and make a successful landing with a significant portion of the trailing edge of the wing missing, almost up to the aft spar, was an A300.

[airsupport]

Yes, I’m sure that is true. There are also people who believe that it was a Tomahawk missile that crashed into the Pentagon on 9/11. There are others believe that extraterrestrial aliens are roaming the streets of Roswell, New Mexico. Maybe they should all get together and have a picnic?

Good idea.

At that picnic I would like to see just how many people believe as I do, that this crash had little to do with the Pilots, rather it was caused by a design flaw with the composite structure, weakened by the continual ingress of water into it because of the routes it operated.

Still we can't have all A300/A310s grounded, better to blame the Pilots.

[bomarc]

barit one

you mentioned the dc3...how many of those came apart in flight due to pilot over controlling the rudder?

I think the dc3 would be easier to certify now than the current 737...

and AIR SUPPORT

see you at the picnic!~ and let's be sure to use safe food handling and avoid food poisioning!

us skeptical pilots are getting rarer and rarer. ;-)

and air rabbit...9 seconds is a long time for an experienced airline pilot. about 6 seconds pass from crossing the threshold of a runway to touchdown on a normal landing ( 50' over threshold, 500 fpm descent...you do the math)

and alot happens there. I've certainly taken over from an inexperienced or screwing up copilot in less time than that. I'll bet air support and others have too.


all of you who think it was the pilot...welcome aboard the airbus 300! all 34 in pax service in the usa.

all of you who think that the pilot was shafted...you have lots of other choices!

[DozyWannabe]

Obtuse doesn't even begin to describe it.

For the last time:

- No-one placed the sole cause, let alone blame, on the pilot.
- The most documented cases of composite fatigue happened on the Concorde, and as a result of that, new techniques of scanning for failures were developed. This is not an unproven technology.

http://www.newscientist.com/article/...te-planes.html

- The loads placed on the vertical stabiliser exceeded design limits (proven beyond reasonable doubt) and even a metal rudder would likely have failed in that situation.

[airsupport]

as a result of that, new techniques of scanning for failures were developed.

Interesting choice of words, they MAY have been "developed" I don't know, but they certainly were NOT in use at the time of this accident.

Our Company operated an Airbus A300 similar to the one that crashed, also based at JFK NY, and also flying primarily down through the Caribbean.

During the 12 months it was based at JFK, the ONLY inspection required (and carried out) to the composite tail was just an external visual inspection.

Combined with this, at every maintenance overnight at JFK, it would take all night to drain the water that was trapped in the tail.

After this terrible accident happened, and having previously seen these inspections, I still wonder if although the desperate actions of the Pilots that tragic day MAY have been what finally snapped it off, the composite structure may well have been degraded dangerously and nobody would have known.

Most accidents in Aviation are a combination of things, rarely if ever one cause.

[DozyWannabe]

Originally Posted by airsupport

After this terrible accident happened, and having previously seen these inspections, I still wonder if although the desperate actions of the Pilots that tragic day MAY have been what finally snapped it off, the composite structure may well have been degraded dangerously and nobody would have known.

http://www.ntsb.gov/events/2001/AA58..._materials.pdf

The NTSB did a full fractographic and electron microscope scan of the surface of the vertical stab and there was no dangerous level of fatigue observed.

Another aircraft in the AA fleet showed signs of disbonding, but this did not make it dangerous.

J.

[airsupport]

Again an interesting choice of wording.

The NTSB did a full fractographic and electron microscope scan of the surface of the vertical stab and there was no dangerous level of fatigue observed.

Someone decided days after the accident, after the tail had been in the water, that there was no "dangerous" level of fatigue, and by ONLY scanning the surface. It is NOT the surface I was concerned about, but the structure and attachments etc.

We just had a strong wind here, which sadly (not really true) snapped off and brought down on our house a big old gum tree. The wind brought the tree down, however I think the tree was rotten through and through, and it was only a matter of time before we had a strong wind.

I would get the NTSB to carry inspections to determine the cause of this disaster, but why bother, they will only spend a fortune looking at the bark of the tree, find nothing wrong with the bark, and blame the wind.

[barit1]

I think (but cannot say for sure) that the "surface" referred to by NTSB is the fracture surface. That's the surface the material science people are interested in.
See the early NTSB releases from last year's Chalk's G-73T crash - they included photos of the lower spar cap fracture surface.

[AirRabbit]

Originally Posted by bomarc

air rabbit...9 seconds is a long time for an experienced airline pilot. about 6 seconds pass from crossing the threshold of a runway to touchdown on a normal landing ( 50' over threshold, 500 fpm descent...you do the math)
and alot happens there. I've certainly taken over from an inexperienced or screwing up copilot in less time than that. I'll bet air support and others have too.
all of you who think it was the pilot...welcome aboard the airbus 300! all 34 in pax service in the usa.
all of you who think that the pilot was shafted...you have lots of other choices!

With all due respect, I am not trying to get into a "one-upsmanship" debate with you. There are quite a few experienced airline veterans here - and I'm sure that more than a fare share of us have "taken away" an airplane from an inexperienced pilot or one who was in the process of "screwing up," as you say.

But, there are times when things ... happen. As I have said many, many times on this thread - I do NOT desire to lay at the feet of the AA First Officer any more of the responsibility for this particular accident than is deserved. I am sure he was a responsible, well-trained, competent, young man, doing his dead-level best to perform honestly and safely. BUT, as I have also said, many, many times on this thread - he WAS at the controls. He DID make those control inputs - or the Captain did. There isn't any other option. When control inputs of that magnitude are made and are almost instantly reversed with equal magnitude, over and over again ... the aviation community has no business attempting to find fault with the structure of the airplane. If the airplane WAS, indeed, structurally inferior or damaged, so be it ... but I have yet to hear from any responsible aircraft structures expert who believes that such control input/reverse, input/reverse, repetitions would NOT have similar consequences regardless of the aircraft involved. The problem that I see is that after having the critique from the B-727 Captain with whom this young man had flown, regarding the ill-advised use of rudder to control the roll that developed after encountering turbulence, that young man or someone responsible for his training, should have revisited at least his training and perhaps queried others regarding the same issues. Of course, hindsight is always better focused – and perhaps the circumstances didn’t rise to that level of concern at that time. If true, it certainly is regrettable – as such a misunderstanding about control application can be rather easily corrected with proper education, training, and procedures.

Sometimes Captains get "caught" in the process of letting a responsible and competent F/O continue to fly the aircraft. As evidence, I would submit the following quote from an NTSB report …

In December, 2003, after final approach into Memphis, the First Officer allowed the airplane to to land so hard that the right main landing gear collapsed and the airplane veered off the runway. The aircraft burst into flame.
The airplane had been in a left crab, but was lined up momentarily with the runway, albeit to the left of the centerline, moments before touchdown. However, the flight data recorder (FDR) indicates that the airplane was a bit high and that the aircraft experienced an unusually high vertical speed. As a consequence, the right main landing gear experienced a vertical speed of 14.4 feet per second (fps). This was more than the 12.5 fps experienced by the left main landing gear. The design limit was 10 fps, and the demonstrated reserve energy was 12.0 fps, which the right gear clearly exceeded.
The gear collapsed during the landing rollout, and the plane fell into its right wing, where friction with the ground pulled it to the right and off the runway.
NTSB investigators attribute the accident to improper crosswind and flare techniques by the first officer and the captain's failure to take corrective actions. "The captain remained silent as the approach deteriorated," said NTSB Capt. Dave Kirchgessner. Yet there were signs that the first officer was not coping well, among them that the aircraft was in a left crab and drifting, that control inputs were not sustained, and that there was no flare, he said. The flight, Flight 647, was a check ride for the first officer, who had experienced an altitude deviation on a previous flight. Her technique was being evaluated by the captain, who was serving as both check airman and pilot in command.

As I said, sometimes Captains get "caught" in the process of letting a responsible and competent F/O continue to fly the aircraft, even when the Captain is there specifically to determine IF the F/O IS responsible and competent.