So you think FDR rudder inputs are measured at the pedals, not at the rudders?
I would like to see what the FDR showed on the MIA Incident when they couldn't move the rudder pedals but the rudder was out of control yawing the aircraft.

Miami Dutch roll • Oct 4, 2013 1:47:44 AM
I say it again AA587 was steady in the turbulent airflow before the unappropriate sharing actions on pedals. Miami is confirmed to have started as a dutch roll due to yaw A/P failure.

A real dutch roll is an OSCILLATION from one side to another with increasing bank due to resonance.

Despite you have a yaw movement in the dutch roll, the names says it well it s a ROLL oscillation, to be corrected with the stick not with pedals.

Don't confuse dutch roll with a low prestall flight that you control with rudder. A stall probably will evoluate to a spin on one side not with that bank oscillation from one side to the other.

Spiral is another situation with bank on a single side.

Lazy eight is already a little different : the dynamic oscillation is present but stays on the step of resonance. The flight remains not really unstable.

In the dutch roll the pilot has a very active role when he flies as learned.

Controling a dutch roll gets really scabrous if you feed his closed loop with energy: and we know that reserves of energy are unlimited so long te plane is not on the ground and stopped (potential and kinetic energy). If you "play" a little more with oscillations or configration or thrust, you continuesly tansfer energy bags... that is very bad! If you know nothing about dutch roll, but have identified it, and have some room under you, the best is to put feet on the ground and hand on the knees : not very easy for a pilot in emergency!! If you are near of the ground, first go around, get altitude...
I suppose you had already applied oscillation abnormal procedure (yaw damper off/alt probably).

Using only the half, or 20%, of the control is not sufisant to overcome quickly a dutch roll. You have to use controls as some exact moment and at exact speed, after you leaved an exact number of seconds action on controls.

The dutch roll closed loop may be controled if you do not pull your plane in furious dynamic. Help the plane to find back quietly his first (!!) order natural oscillation (stopping to shake it!) , don't try to compute in your head when piloting an emergency a second, third, fourth degree system you builded yourself by that shaking : it is just impossible.

Let us jump here equations which don't figure in the well known n/speed stall and gusts enveloppe. But sailors know something looking like dytch roll, the French name is "roulis rythmique". Another similar dynamic is that of the toreador : banderillas are used to oblige the animal to use only first degre movement.

The dynamic of the dutch roll affects not only the position and attitude and bank of the dutch rolled pkane, but also the airflow around the plane, resulting in the very strong effect catching the plane as in a net and doing very difficult some movements. Miami report shows that phenomena which has to do with our bad knowledge of ..theory of lift.

AA587 wasn't a dutch roll. It started with wake turbulence and ended up with rudder movement causing the VS to fail. The question is was it pilot induced or did the airplane do it. I believe the airplane did it. Our MIA incident at their speed if repeated could be why it happened. I think the FDR actually measures the rudder movement, not pedal movement so would like to see the read out of the MIA incident vs JFK crash and compare them. MIA, the pilots couldn't move the rudder pedals but JFK it shows full deflection. Did anybody ever bother to compare them? Probably not. If I was in the NTSB I would because the FO is being blamed for what the rudders did but I don't think he pushed the rudders, the A300 systems did again. I could be wrong but I don't think so.

Something I'm finding very disturbing about this thread is the suggestion/implication that the NTSB and FAA are incompetent or corrupt. I'm wondering how many of the people making these suggestions have actually dealt with the FAA during an aircraft certification, or worked with the NTSB during an air safety investigation?

Having done both (I became a DER 25 years ago and I've been involved in multiple air-safety investigations), I find the implications insulting to those involved. My experiences have been just the opposite - people obsessed with covering every possible detail, with impeccable ethics and integrity.

Bubbers, do you honestly believe no one in the NTSB considered the possibility that the rudder movements were uncommanded, and looked at data/research that convinced them otherwise? Does Teldorserious really think that they faked the data that said the tail failed at 2.2x design load (well above the FAR mandated 1.5x)? These are not mindless government agencies we're talking about - they are real flesh and blood people. People that know that other peoples lives literally depend on them getting it right.

Now, that doesn't mean I always agree with the FAA/NTSB - heck I can think of times when the FAA and NSTB couldn't agree with each other, and even times when different branches of the FAA couldn't agree with each other. But these fell into the realm of honest differences of opinion between engineers - something that happens with some regularity between even the best engineers.

So, before you make another post slandering these people, you might want to think about what exactly you're posting.:ugh:

As for aircraft design parameters that would allow a pilot (or terrorist) to break an airplane tail on purpose, it seems to me that a pilot (or terrorist in control of an aircraft) has the ability to intentionally crash an airplane pretty much any time they want, no matter how strong we make the tail :mad:

tdracer – Please accept my compliments for a well worded and very well positioned post.

There are some here who are somewhat more knowledgeable about some things whereas others may not be – and that’s simply a fact of life. Throwing insults at peopole or organizations just because the work they do may not be understood or appreciated – is the height of ignorance spiced with laziness. Thanks for bringing a level head to the table.

As I’ve been trying to convince some here, this accident was NOT caused by the wingtip vortices generated by the preceding JAL747. Yes, that preceding airplane did generate wingtip vortices – and yes, AA587 encountered both of them. The first encounter was handled professionally and rather easily by the pilot flying (the F/O) and his response was precisely what he was taught. However, the second encounter was not handled well at all … and it was contrary to what he had been trained to do. He was trained - and he did perform correctly … the first time. The question should be, why did he do almost the opposite of what he had just done very successfully?

Additionally, there are some here who stubbornly hold to the concept that the rudder displacements – clearly seen on the FDR – were a result of the vortex encounter – not rudder pedal inputs. HOWEVER, as I’ve also been trying to convey to these folks, the rudder was displaced by the pilot flying – and done deliberately (and could easily be described as a “panic” response – which is what I believe caused him to respond so distinctively different from the way he had just responded to exactly the same kind of stimulus) all of which were excessive, and most of which were at - or beyond - the control limits … and reversed each of those inputs at least 5 times in a 7 second period. And, before those same naysayers jump on this issue claiming that rudder pedal position is not an FDR parameter – YES IT IS. While it wasn’t originally installed on the A300-600 at construction, American DID install a modification (to be in compliance with the requirement that was to soon become effective) that recorded the control wheel, control column, and rudder pedal positions on the FDR. And NO, these are not back-driven controls – and that is the reason for the requirement for the completing the FAA-mandated modification … to be able to record those control position inputs as well as the resulting control surface positions. The FDR clearly shows that the rudder pedals were used to command the rudder surface position. In fact, the NTSB had produced an animation of the FDR readouts showing the cockpit controller positions (column, wheel, and pedal) as well as rudder position with superimposed markers showing the relevant control limitations that adjusted as airspeed increased. I used to have a copy of that animation but I don’t have it with me. Perhaps some here may have or know how to acquire that animation – it shows what happened quite clearly ... and it is quite sobering.

As many have said here … I, too, get no satisfaction out of criticizing another aviator – but facts are facts – and we can choose to ignore them or examine them. Personally, I’d prefer to examine them and learn, if we can, why a well-trained aviator could become so easily panicked as to do what this well trained and otherwise competent aviator did.

Sure, we can criticize training programs ... and simulators ... and instructors all day – but unless we know the facts – such criticisms are simply howling at the moon – a lot of noise, drawing some attention, and accomplishing nothing.

So, how do you explain this:

This is a verbatim quote from a revision to the US Air Force's KC-135 operating manual.

The KC-135 is a *Boeing*

This revision was published on 30 June 2000.

That was more than a year before the AA587 crash.

OK, once again; this has been addressed before and either you missed it or you're ignoring it because it doesn't fit with your theory.

The FDR records position of *both* the *rudder* and the *Rudder pedals*

The FDR positions from the accident of *both* the Rudder and rudder pedals agree.

The Yaw Damper acts through an averaging mechanism which prevents yaw damper movements from moving the rudder pedals.

If the yaw damper moved the rudder, the pedals would not have moved

The rudder pedals moved.



Even though that is contradicted by all the evidence.

It measures and records *both*

Yes, the NTSB did

Yes, the NTSB did

They did


Sorry to keep repeating, but this has all been posted before. How many more times does this have to be repeated before you read what is being posted?

A Squared. Stop being so nasty to Bubbers. His belief is that all American pilots are infallible. :rolleyes:

Who are we to question that fallacy?

bubbers

One has to admire your tenacity in defending your colleagues, but I fear you are now clutching at straws. As has been said several times both pedal position and rudder deflection were recorded and reported. This is an extract from the Performance Group's appendix to the NTSB report - sorry I don't seem to be able to make it smaller.

roulis

Dutch roll is certainly an oscillation, but it doesn't have to be one of increasing bank; in fact it would be a lousy aircraft for which that were true - very probably unflyable. Increasing bank as a result of suitably (mis)timed pilot inputs is quite another thing.

Sure the rolling motion is usually the most obvious sign of a dutch roll, but the motion is a combination of two oscillations - one around the roll axis and the other around the yaw - linked together by a common driver - sideslip.

Way back in the 1950s Ashkenas and McRuer established the importance of the roll/sideslip ratio as a parameter to describe the goodness/badness of dutch roll. The larger the number the worse the aircraft basically. So dutch roll can be triggered by rudder application, but as you say it is best controlled by aileron.

So far as I know, the A300 was not noted as having poor dutch roll characteristics.

Nope, in investigating an accident resulting from rudder movement, it just never occurred to the NTSB to examine part of the autopilot which actuates the rudder.

That's sarcasm. Of course they examined the a/p rudder actuator. The clutching mechanism was disengaged. Read about it in Addendum #5 in the Systems group Factual Report.

I usually keep l out of conversations involving either AA587 and TWA 800:ouch:

Hear! Hear!

LSM,

I trust you meant American Airlines pilots are infallible. Lots of us mere mortal American pilots make mistakes, sometimes, with a blue moon shining. :cool: :}

Although it hasn't been specifically referred to on this thread, there does exist a group of pilots - mostly of a certain generation - who retain a degree of hostility to the NTSB because of the TWA "Hoot" Gibson case. The NTSB made a judgement call there that with 20/20 hindsight could be considered shaky at best - however not only was this almost 35 years ago, but also the call was made due to a lack of hard data because of the primitive nature of the FDR. As has been pointed out, the FDR on AA587 was much more advanced and recorded the relevant parameters separately.

Putting that case in historical context, it can be seen almost as an aberration - as in accident reports both prior and following, the NTSB (post-separation from the FAA) showed no significant bias towards one party or the other.

Much the same could be said of the French BEA and AF296 (except in that case they made the correct call, but it didn't end the controversy).

I know of only about five people who even know of Hoot Gibson (that one, not the SW one).

Acknowledging Dozy, who are the other 3?

I meant of the people I've flown with.

Thanks Dozy - I had to Google that one (the only "Hoot" Gibson I knew of was the Space Shuttle pilot - I have a SS model around he that he autographed :)).

After I found the Wiki, I vaguely remember hearing about that incident (I was a young, fresh faced engineer at the time) but didn't know it had become so controversial. There was a story going around Boeing at the time that the crew "accidentally" erased the voice recorder after landing (no idea if it has any truth). Doesn't sound like the NTSB's finest hour :rolleyes:.