He stepped on the Rudder and redefined Va [Archive]

roulishollandais

26th Sep 2013, 06:26

I don't think the FO did that because the captain would have stopped him if he did. Would any captain let his FO do this? I wouldn't. We had an A300 have out of control rudder movements landing at MIA and both pilots felt they were going to crash prior to this event. We have two very different situations :

- The flight AA587 was tooken in a heavy and quick wake turbulence and the first officer did that violent pedal sharing very quickly - probably the captain had feet on the ground and could not avoid his FO pedaling quickly enough. It is a non pilot induced big oscillation of the airflow where the A300-600 had a stable dynamic, followed by a pilot action near of shocks giving excessive conventional aerodynamic forces.

- In the both cases with Yaw damper failure, the possibility of DUTCH ROLL is important. You avoided it on your B727. Your friend and his Captain had less chance and developped the dutch rolll which is a resonance between the airflow movement around the whole aicraft and action with roll and/or rudder of the pilot to stop that PIO - inadequatly because the dutch roll is not taught to pilots nore described in ATPL books, where the problem is described as non existing with the yaw damper . But dutch roll may start by other initial disturbation - pushing one pedal violently (..in a sim is safer :}) - and the pilot feeds himself the resonance acting on the stick and pedals AT THE WRONG MOMENT AND WITH INADEQUATE SPEEDS. A good aerobatic flight culture may avoid/correct that resonance without equation, but it may be solved, in flight, by equations too.

About the SOP, I already told that Learjet had elaborated that poor and dangerous method of rapid pedal sharing movements after years of fears and some accidents to try to stop their genetic dutch roll. As nobody around the world wanted to teach pilots about dutch roll and other PIO - labelled as "pilot FAULT" and sometimes "human factor" (sic):bored: - in case unions would use it anyway, that bad bar SOP was used - around the world in our lovelly international community :) - against any unwanted oscillation and turbulence ,and perhaps applied in the Queens accident AA587.

Volume

26th Sep 2013, 07:25

the four jet transports I've flown either had a rudder limiter or a placcard about control use. that plane would still be flying if it had a rudder limiter based upon speed.All those jet transports have limiters which limit the rudder so that it is safe at any speed to apply one full rudder input. Reversals are destroying any of those aircraft.
some pilots, myself included, think the problem was not in the pilots/copilots feet.I agree, the problen was most probably more at the top end of the pilot/copilot...
No pilot is a normal state of mind would think, that he can safely do several full elevator reversals at that speed. So why should full ruder reversals be OK? On the other hand, would any pilot is a normal state of mind reverse the rudder at a 0.3 to 0.4 second frequency?

SMOC

26th Sep 2013, 08:42

I was taught from day one when flying large airliners that the rudder was for crosswinds and engine failures that's it, even in upset attitude training I was told to avoid using the rudder and this was 20yrs ago.

Also having been inside section 48 of the 747 and inside the fin I can assure you all it's not attached as securely as some people here seem to think. So don't go thinking it's some deficiency of Airbus, Boeing recommended exactly the same thing regarding rapid rudder reversals.

Photos: Boeing 747-206BM(SUD) Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/KLM---Royal/Boeing-747-206BM(SUD)/0952826/L/)

There are no spars running through into the fuselage it's simply bolted on top.

DozyWannabe

26th Sep 2013, 14:00

I think it was an airframe problem, either the patch or maybe another yaw damper malfunction.

You're entitled to that view, but that then begs the question of why a supposedly weakened structure did not fail until the load on it was almost double the Ultimate Design Load that the engineers had calculated. If anything the vertical stab and attachments were *stronger* than the designers thought - not weaker.

Pugilistic Animus

26th Sep 2013, 15:06

bubbers44, without getting into the contraversy of AA587, my only point is that cycling the flight controls is extremely dangerous...no airplane is meant to take it

tdracer

26th Sep 2013, 15:28

Roughly 30 years ago, while flight testing an E6 (a military version of the 707 with CFM engines), they suffered serious vertical tail damage. I don't recall what they were doing at the time (it may have been flutter testing but it's been a long time so the memory is fuzzy).

What's not so fuzzy is that I happened to see that airplane parked in a hanger at Boeing field shortly after the incident. Roughly half the vertical tail and nearly all the rudder were missing :mad:

I don't seem to recall anyone ever claiming that the 707 airframe wasn't robust.:=

DozyWannabe

26th Sep 2013, 15:38

Your friend and his Captain had less chance and developped the dutch rolll

As I recall, the AA587 situation was not indicative of Dutch Roll as much as it was repeated sideslips in opposite directions.

Aircraft with wing-mounted engines require rudders with more control authority than those with tail-mounted engines because the adverse yaw in an engine-out scenario is much greater. To give an example, both the Air Transat and Gimli Glider incidents used a single sideslip to slow the aircraft down, and in the latter case, the Captain was concerned about what that sideslip would do structurally if it was held too long. As such, it was a last-ditch move.

Reversing a sideslip once, let alone repeatedly and in quick succession, will break any airframe eventually.

[EDIT : Additionally, if the yaw damper input was the source of the oscillations, it would have shown up in the FDR. ]

I don't seem to recall anyone ever claiming that the 707 airframe wasn't robust.:=

You clearly never encountered the late 411A... :E

roulishollandais

26th Sep 2013, 16:22

two very different situations :

- The flight AA587 [...]conventional aerodynamic forces.

- In the both cases with Yaw damper failure [...] Dutch roll Dozy,
It seems that my text was unclear : the both cases were Miami and Bubbers44's B727 flight and did not correspond to the two situations.
In my post I suspected a dutch roll as possible, in the Miami flight, and in Bubbers44's B727 flight (avoided by Bubbers44 aerobatics experience), and not in the AA587 flight.

The connexion I am asserting, between AA587 and dutch roll, is that AA587 used a unfounded and dangerous method, created against Learjet's dutch roll generalized to other oscillations too, as nobody worried about dutch roll and other oscillations. Telling about PIO experiences has during a long time been considered as totaly taboo (not sure it is finished).

In any situation that rudder pedaling is dangerous.

edit : add that PS : If you have a dutch roll, accept the yaw damper outputs as they are (adapted or failing, you can do nothing, only the ground), but only the pilot's input on stick and pedals can - and must - be modified and adapted to stop increasing that crazy oscillation (and high negative Vz) and stop the oscillation and stabilize attitude and path so much as possible (once more inertial data HUD may help).

AirRabbit

26th Sep 2013, 21:38

During the last 10 days of 2006 through the first 8 or 10 days of 2007, there was an extremely "inspired" (some might use the descriptive terms "emotional," "heated," or "impassioned") discussion on this very subject – and, as my memory serves, all of the points of view raised here were taken into consideration at that time – and I would presume would remain essentially the same today. Therefore, I see no particular advantage in attempting to repeat the rather lengthy posts I made during that time in this forum’s history. Suffice it to say that the F/O at the controls of that ill-fated flight made control inputs that no one can deny. Of course the speculation will continue as to the cause – poor airplane design – poor pilot training – an absence of knowledge of airplane certification processes – belief that some airplane manufacturers are more interested in covering “their 6” than speaking the truth – and on and on and on. I’m not sure of what kind of archives may or may not exist on this forum … but it might be worthwhile having those on this forum today read what was said during that 20-day period almost 7 years ago. Since that time, I have seen some major training adjustments and some significant changes in the pilot population having a much better understanding of the terms AND what those terms mean. However, there are some who will refuse to spend the time to read AND understand, believing that simply reading the material or relying on their own knowledge and experience will be sufficient. It’s those persons I would prefer to NOT fly with, thank you. We go through the process of accident investigation, not to fix blame, but to fix problems … when and where they may be found. If we get to the point that blame and consequences are more important than finding out what went wrong and attempting to find ways to prevent the same thing from happening again – I will feel as though the description of “professional pilots” will have to be changed simply to “airplane operators” – with no adjective included. That, to me, will be a dark day for all of us! :ugh:

DozyWannabe

26th Sep 2013, 22:04

@AirRabbit - I remember it well. I believe there are some search tips (using Google) at the start of the AF447 thread that will get you the material. I'll have a go myself later.

...belief that some airplane manufacturers are more interested in covering “their 6” than speaking the truth...

Well, the legal departments of *all* major corporations, be they manufacturer, airline or whatever will do that - they wouldn't be doing their job otherwise. That said, investigative authorities have become a lot better at sorting the wheat from the chaff in the last 25 years or so.

Agree with everything you said.

Teldorserious

26th Sep 2013, 23:12

Oh gee wiz...anyone in here see acro planes, student trainers, even tprops and bizjets during training, people are standing on the rudders, back and forth all day long, year after year for decades...not one tail has fallen off..

What gets me is that the really funny kinds of accidents that defy logic seem to happen in Airbus's...

The only double engine failure ever due to birds?

The only crash where three pilots lose complete SA in level flight completely lost, right until the they impact the water?

The only tail coming off on departure at slow speeds?

Didn't some Afgani AB go down because the FO's seat slid back? Where was the captain?

DozyWannabe

26th Sep 2013, 23:32

What gets me is that the really funny kinds of accidents that defy logic seem to happen in Airbus's...

Really?

The only double engine failure ever due to birds?

Eastern Air Lines Flight 375 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_375) (Lockheed Electra - quadruple failure - fatal)
Ethiopian Airlines Flight 604 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_604) (B732 - double failure - fatal)

The only crash where three pilots lose complete SA in level flight completely lost, right until the they impact the water?

Birgenair Flight 301 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Birgenair_Flight_301) (B752 - fatal)
Flash Airlines Flight 604 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Flash_Airlines_Flight_604) (B733 - fatal)
Northwest Airlines Flight 6231 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Northwest_Airlines_Flight_6231) (B722 - fatal)

The only tail coming off on departure at slow speeds?

See previous posts - Boeing determined that those inputs would have exactly the same result and changed procedures accordingly.

All manufacturers have their flaws and Airbus are no exception - but at least do your homework before making sweeping claims like that!

Teldorserious

27th Sep 2013, 01:35

Dozy - Two things...do you really believe that if you took off any plane, on climbout that if you stood on the right rudder, then the left, then the right, the tail would come off? You should see what people do in aircraft...still here...

Secondly, I am just waiting for a Va placad to be put in planes...

Va-200kts

except if you push the rudder a little too much back and forth,at a non specific airspeed, and don't pull up or push down to much either because we don't test for full scale deflections either..so in summary, just don't move the controls, too much, at any speed, just to be safe.

Pugilistic Animus

27th Sep 2013, 02:42

Va is the maximum speed which any ONE of the flight controls can have a maximum deflection without exceeding design limit load... If other flight controls except the elevator are not limiting then Va is a function of stall speed and design limit load. This post is poorly worded...but even unlimited aerobatics champions don't reverse the flight controls rapidly they always unload first.

tdracer

27th Sep 2013, 04:29

It occurs to me that an important detail has been left out of the debate:

The rudder inputs were so violent that the engines ripped off the pylons :sad: :eek:.

Again, still not in the habit of defending Brand A, but Boeing uses sheer pins to allow the engines to separate the aircraft in certain extreme circumstances - e.g. rotor seize or a wheels up landing - to avoid more serious damage. For example, the stresses from a high-power rotor seize can potentially fail the wing structure - better to let go of the engine. :rolleyes:

If the rudder oscillations are so severe that the engine struts fail, does it really matter much if the vertical tail stays intact? It occurs to me that if the engines have departed the aircraft, you're pretty much guaranteed to have a bad day :sad:

latetonite

27th Sep 2013, 05:52

Tdracer: not sure if i'd agree on that one.
Boeing syllabus trains pilots for an engine separation, but not on a vertical fin separation.

DaveReidUK

27th Sep 2013, 06:55

It occurs to me that an important detail has been left out of the debate:

The rudder inputs were so violent that the engines ripped off the pylonsProbably left out because that isn't what happened.

steamchicken

27th Sep 2013, 13:32

RAF Nimrod MR2 out of Kinloss - birds into all four engines, all lost.

JammedStab

27th Sep 2013, 15:36

engine separation occurred during the
out-of-control airplane motion that followed the separation of the vertical stabilizer.

SMOC

27th Sep 2013, 16:12

Oh gee wiz...anyone in here see acro planes, student trainers, even tprops and bizjets during training, people are standing on the rudders, back and forth all day long, year after year for decades...not one tail has fallen off..

Are you seriously comparing those to large jetliners :ugh:

Have a read about the square cube law.

In mathematical terms, the law states that when an object increases in size, its weight multiplies faster than the strength of the structure that supports it.

SMOC

27th Sep 2013, 16:16

Boeing uses sheer pins to allow the engines to separate the aircraft in certain extreme circumstances - e.g. rotor seize or a wheels up landing - to avoid more serious damage. For example, the stresses from a high-power rotor seize can potentially fail the wing structure - better to let go of the engine.

Nope not any more.

After the El Al crash the 747 fuse pins were changed to steel and additional attachments were added to all 747s to prevent separation. I believe this is the case with all Boeing now.

I have one of the old fuse pins on my desk as a paper weight.

AirRabbit

27th Sep 2013, 17:27

AirRabbit

However, there are some who will refuse to spend the time to read AND understand, believing that simply reading the material or relying on their own knowledge and experience will be sufficient. It’s those persons I would prefer to NOT fly with, thank you.

Teldorserious

Oh gee wiz...anyone in here see acro planes, student trainers, even tprops and bizjets during training, people are standing on the rudders, back and forth all day long, year after year for decades...not one tail has fallen off..

What gets me is that the really funny kinds of accidents that defy logic seem to happen in Airbus's...
The only double engine failure ever due to birds?
The only crash where three pilots lose complete SA in level flight completely lost, right until the they impact the water?
The only tail coming off on departure at slow speeds?
Didn't some Afgani AB go down because the FO's seat slid back? Where was the captain?

I rest my case.

Teldorserious

27th Sep 2013, 17:35

SMOC - Using your logic, that airliners are weaker as they are bigger, as opposed to the way aircraft are tested to withstand x loads at y speeds...then I will run with your premise and see how it Socratically follows out..

Two planes take off into turbulance..one is a biz jet, another is an airliner.

Both are flown 1kt below Va, both are getting slammed around, both crews are doing what they can to keep the rubber side down.

In the ensuing departure, airline test pilot A, steps on the right rudder as hard as he can, all the way to the stop, then the left, then the right..the tail comes off, they don parachutes and bail out.

In the ensuing departure, bizjet test pilot B, gives a Jean Claude Van Damme kick to the right rudder, then then left, then right. Flight procedes normaly.

According to your view of how aircraft are certified the bizjet is an inherently more robust aircraft.

Blantoon

27th Sep 2013, 18:57

I should be quiet if I were you Teldorserious, lest you dig yourself a bigger whole.

Teldorserious

28th Sep 2013, 00:53

galaxy flyer

28th Sep 2013, 02:50

The structural certification standard never envisioned rapid reversals of the flight controls. Va does not imply a strength criteria, it merely is the point at which the wings stalls at the G limit, thus relieving the wing loading. No plane is tested for rapid reversals; similarily asymmetric G load limits are published for FA 25 aircraft, but the exact.

GF

roulishollandais

28th Sep 2013, 03:42

During the last 10 days of 2006 through the first 8 or 10 days of 2007, Nobody mentioned the Learjet method of rapid :mad: sharing movements of the pedals used with much superstition against endemic dutch roll or any not understood oscillation - PIO or other oscillation. Isn't?

AirRabbit

28th Sep 2013, 04:05

This is directed to anyone who may be interested and specifically to Mr. Teldorserious.

You know … throughout my participation on this forum, while it may have only been 8 years or so, I believe I have always tried to maintain some sense of professionalism with the others who participate here – even when they were off into some of their own beliefs – as limited as they were (and recognized as such by many other participants). So, if you would not object, I would like to suggest that you might consider reading the section of the rules that govern the certification of various kinds of airplanes.

In the US, those rules are written, published, and enforced by the FAA – in other countries those responsibilities fall to other organizations. As for the US, the section of the rules that govern the certification of transport category airplanes (like the A-300) is Part 25. This particular FAR Part addresses large civil airplanes and large civil helicopters. Transport category aircraft include jet-powered airplanes with 10 or more seats or with a maximum takeoff weight (MTOW) greater than 12,500 lb (5,670 kg); Propeller-driven airplanes with more than 19 seats or with a MTOW greater than 19,000 lb (8,618 kg); and Helicopters with a MTOW greater than 7,000 lb (3,175 kg). In the example you posted (an airliner and a “bizjet”) if the bizjet met the requirements to be certificated under the rules applicable to Transport Category jet powered airplanes, then, yes, both airplanes would be held to the same standard. You might wish to review the “yaw” standards posted in §25.351 - Yaw maneuver conditions. Here are those requirements:

The airplane must be designed for loads resulting from the yaw maneuver conditions specified in paragraphs (a) through (d) of this section at speeds from VMC to VD . Unbalanced aerodynamic moments about the center of gravity must be reacted in a rational or conservative manner considering the airplane inertia forces. In computing the tail loads the yawing velocity may be assumed to be zero.
(a) With the airplane in unaccelerated flight at zero yaw, it is assumed that the cockpit rudder control is suddenly displaced to achieve the resulting rudder deflection, as limited by:
(1) The control system on control surface stops; or
(2) A limit pilot force of 300 pounds from VMC to VA and 200 pounds from VC /MC to VD /MD , with a linear variation between VA and VC /MC .
(b) With the cockpit rudder control deflected so as always to maintain the maximum rudder deflection available within the limitations specified in paragraph (a) of this section, it is assumed that the airplane yaws to the overswing sideslip angle.
(c) With the airplane yawed to the static equilibrium sideslip angle, it is assumed that the cockpit rudder control is held so as to achieve the maximum rudder deflection available within the limitations specified in paragraph (a) of this section.
(d) With the airplane yawed to the static equilibrium sideslip angle of paragraph (c) of this section, it is assumed that the cockpit rudder control is suddenly returned to neutral.

I would call your attention to this last paragraph … where the airplane would be yawed to the static equilibrium sideslip angle and then the rudder control is suddenly returned to neutral. And we all should note that neutral is not full opposite rudder. While I am sure there are those on this forum who could provide chapter and verse and the formulas involved to calculate the inertia of the mass being “yawed” and what kind of force is generated on the vertical structure if full opposite yaw control (rudder pedal) were applied while the mass was moving in the original direction. If the airplane structure could withstand such reckless use of the rudder controls, all the better for the airplane – but to meet regulatory requirements, it is not required. There is no allowance for any transport category airplane anywhere (at least that I am aware of) that would not have a rudder application limit – and a cavalier “Van Damme kick to the rudder” at any time or place would likely result in that pilot’s immediate dismissal – assuming he and his airplane made it safely back to terra firma.

Tails of transport category airplanes do not “come off” at speeds under Va … or over Va … if the airplane is flown the way it was intended (and certificated) to be flown. In this particular case (AA587), the pilot flying successfully transitioned the first of two vortex encounters quite nicely – in fact, looking at the FDR, it was almost, if not, Textbook. The second vortex encounter was wholly different in that same pilot’s response. I have no idea if you have personally looked at any of the data applicable to this specific accident – if not, it would serve you well to do so … before you get to the level of conclusions that you’ve apparently reached without that kind of research/reading. However, and to alleviate your having to stomp around in knee-deep records, let me offer the following:

I’ll start by focusing on the initiation of the 2nd vortex encounter (and lest you wonder, my observations are directly from the FDR-generated display provided by the NTSB for this accident). The first control movement looks like it begins with a very small aileron correction to the left as the airplane looked to be ever so slightly beyond the 22-degree bank that seemed to be what the F/O was happy with during the departure turn as directed by ATC. Almost immediately we see a right rudder pedal deflection to the stop and a control wheel input of about 80 degrees to the right. The attitude indicator just prior to this looked to be relatively steady. Of course, with full right rudder and darn near full aileron to the right, the airplane begins a roll to the right (back toward wings level). However, when the airplane reaches about 20 degrees of left bank, while rolling to the right we see a simultaneous control wheel and rudder surface movement to the left. The rudder surface actually looks to exceed the pedal limit (but I don’t know if this is an anomaly with the indicator or not) and the control wheel gets to or awfully near to full control wheel displacement. This means at least 160 degrees of wheel change and probably something like 8 – 10 degrees of rudder surface change – all in 1 second, to the left as the airplane is rolling to the right. With all this opposite control surface input, the roll to the right is almost stopped (at about 10 degrees of left bank).

To add to the excitement, the full left aileron position is not maintained, nor is the full left rudder pedal position. The wheel is brought back to something like 10 degrees to the right simultaneously with application of full right rudder pedal deflection, again in 1 second, probably reaching constant rate saturation. While full right rudder is maintained, the control wheel is moved back to about 10 degrees left – again, in 1 second. As the rudder pedal deflection is maintained (very likely getting close to a stable sideslip), the control wheel is moved back to the right to just about full wheel travel and the rudder pedal exceeds the pedal limits (again, I don’t know if this is a display anomaly or if the actual limit was exceeded) – again taking a total of 1 second. Immediately, the rudder pedal is repositioned to full left deflection, and, in fact, goes well beyond the limits (again depending on the accuracy of the display), simultaneously the control wheel is deflected full left … again taking only 1 second. As the control wheel is moved back to the right (to about 45 degrees left), the rudder pedal deflection goes full right and the surface position presentation disappears, while the pedal position continues to show full right deflection. There is little doubt that this is where the data feed was stopped – probably because of the departure of the vertical stabilizer and rudder. The control wheel goes back to about neutral and back again to a right control wheel deflection of about 45 degrees.

The pitch attitude when this second event began was about 10 degrees nose up and the airspeed was 238 knots. By the time the rudder surface position display blanks out, there were 7 control wheel reversals and 5 rudder pedal reversals, all in about 7 seconds … and in this 7-second time frame the pitch goes to zero degrees and the airspeed increases to 251 knots.

Again, as I noted earlier, when an airplane is in a maximum equilibrium yaw, a sudden commanded full, or nearly full, opposite rudder movement against that sideslip can generate loads that exceed the “limit loads” and possibly the “ultimate loads” and can easily result in structural failure. I think the professional investigators reached this conclusion and if you have access to that NTSB produced video, you would likely see the same events and come to the same conclusion.

bubbers44

28th Sep 2013, 04:22

I don't think dutch roll had anything to do what we are talking about. I think rudder movements caused the AA 587 crash and I will bet it had nothing to do with FO rudder movements. Yes, the rudders moved but what moved them? Where does the FDR sense the movement? I think it is the rudder actuator so what caused the actuator to move?

My first thought would be yaw damper, not a totally stupid pilot stomping on his rudders. I think both pilots were along for the ride because the captain would have prevented FO oscillations as all of us would. The yaw damper malfunction has happened before as in my previous post.
The FO didn't cause it in my opinion. NTSB has political pressure to lean to what works their way.

roulishollandais

28th Sep 2013, 05:51

Va does not imply a strength criteria, it merely is the point at which the wings stalls at the G limit F = M x G =» G limit is an expression of strength limit

Owain Glyndwr

28th Sep 2013, 06:58

An interesting discussion, if only to demonstrate the longevity of misinformation circulating on the 'net ;)

AirRabbit

Well said :)

bubbers44

Yes, the rudders moved but what moved them? Where does the FDR sense the movement? I think it is the rudder actuator so what caused the actuator to move?

My first thought would be yaw damper, not a totally stupid pilot stomping on his rudders. If you read the NTSB report and the performance group appendix you will see that AA installed additional instrumentation specifically to record cockpit control positions and forces. On p75 of the appendix you will find rudder position and pedal position; on page 77 you will find pedal forces. All of these correlate with each other, so I find it difficult to see how you can claim that FO input had nothing to do with this accident. How does the yaw damper provide forces at the pedal???

Teledorserious

To go back to your original post, could you please point me towards the actual FAA change to Va? I failed to find it.

TURIN

28th Sep 2013, 07:08

Air Rabbit. An excellent post.
Unfortunately, there are none so blind as them as can't see.

The conspiracy theorists will have it their way no matter what the evidence.

Bubbers, take note.

Posted from Pprune.org App for Android

mono

28th Sep 2013, 08:32

For Bubbers,

The yaw damper would not have moved the pedals. It's a series yaw damper so rudder surface deflection occurs independent of pedal input. Secondly, yaw damper authority is a fraction of the full rudder travel.

bubbers44

28th Sep 2013, 09:02

mono, the A300 yaw damper might not move the pedals but my friend felt they were going to crash trying to land at MIA because of the violent yawing causing them to go around. I wasn't there, just heard the story.

To me it seems more probable than pilot input why AA587 lost it's VS.

SMOC

28th Sep 2013, 09:33

Bubbers, read the post above.

yaw damper authority is a fraction of the full rudder travel

Meaning the yaw dampers maximum input can only mover the rudders a fraction so can't have caused violent yawing.

For example the 747 rudder can move +/-32 degrees however the yaw damper can only move the rudder +/-4 degrees.

You need a power control unit (PCU) failure like the 737 to command full and violent yaw.

flyboyike

28th Sep 2013, 13:43

Tails of transport category airplanes do not “come off” at speeds under Va … or over Va … if the airplane is flown the way it was intended (and certificated) to be flown.

One of the things I discovered in the aftermath of AA587 was that a fair number of pilots seemed to understand Va as that speed below which ANY maneuver is ostensibly safe. That's not how I was taught. I was taught more to the effect that below Va any NORMAL maneuver is safe, and certainly dancing on the rudder stop-to-stop is not a normal maneuver, at least in my opinion.

Clandestino

28th Sep 2013, 15:25

I was recently interviewed for nonTR DEC position. Questions I was asked (among the others) were:

- which scheme correctly depicts model of solar system, followed by sketches of the Sun, the Earth and the Moon circling around each other.
- if aeroplane A has twice the mass of aeroplane B, at the same speed its kinetic energy is a) half of B b) the same c) quadruple of B d) double of B
- if aeroplane A has twice the speed of aeroplane B for the same mass, its kinetic energy is a) half of B b) the same c) quadruple of B d) double of B
- pendulum of larger mass and the same length at the same free fall acceleration has a) higher b) lower c) same frequency compared to lighter one.

Thanks to PPRuNe, I wasn't bewildered by the need to ask such questions and appreciated the reason behind them.

Folks, you are welcome to ask questions, whoever knows (or thinks he knows) the correct answer will be happy to reply, we all might learn something useful from discussion, but If you insist on obstinately pushing forward theories that have nothing to do with reality, you just have no right to feel offended if your efforts are not appreciated.

No, he did not step on the rudder and redefined Va. If he did and tail separated, he would have redefined it. He rapidly cycled the rudder under conditions where no rudder input at all was necessary, thus wiping out himself, his crew and his passengers from existence and posthumously opening the can of worms:

One of the things I discovered in the aftermath of AA587 was that a fair number of pilots seemed to understand Va as that speed below which ANY maneuver is ostensibly safe. Sadly, correct. That's why every manual I've come across in last couple of years has warning of possible airframe failure if controls are cycled even below Va.

I was taught more to the effect that below Va any NORMAL maneuver is safe, and certainly dancing on the rudder stop-to-stop is not a normal maneuver, at least in my opinion. Opinion correct.

flyboyike

28th Sep 2013, 15:40

Folks, you are welcome to ask questions, whoever knows (or thinks he knows) the correct answer will be happy to reply, we all might learn something useful from discussion, but If you insist on obstinately pushing forward theories that have nothing to do with reality, you just have no right to feel offended if your efforts are not appreciated.

Careful now, I got banned for saying something pretty similar, albeit not as elegantly.

AirRabbit

28th Sep 2013, 16:41

It may be appropriate to offer just a tad more information on this specific issue… Not a lecture ... more of a plea ...

I think it quite valuable to understand the factors involved in the loads experienced on the vertical stabilizer / rudder under conditions when an airplane is “yawed” into a sideslip. A sudden rudder deflection will start a yaw, and, if the deflection is at maximum, you get the maximum rudder load. With this condition, the yaw will move the airplane tail to what is called an “over-swing” position. Once getting to that position, the airplane will experience the maximum torsion on the vertical tail. With the rudder in that position, the maximum force on the vertical stabilizer and the maximum force on the rudder surface are opposite each other. With the rudder held in this maximum deflected position, the airplane will oscillate from its “over-swing” position, and dampen down to a position known as “equilibrium yaw.” The same analysis is performed for engine failure, for rolling moments, and lateral (side-to-side) gusts. The most severe of these cases provides the design basis for the vertical stab and the rudder and is called the “limit load.” Here is where the 1.5 factor comes into play. The “ultimate load” is described as the “limit load” multiplied by 1.5. The structure must be able to support the “limit load” without permanent deformation that is detrimental to flight AND support the “ultimate load” without failure. The time for this test is 3 seconds. If either failure occurs within that 3 seconds, the test is failed. But (and it’s a VERY BIG “but”) when the airplane is in this maximum equilibrium yaw, a sudden commanded full, or nearly full, opposite rudder movement against that sideslip can generate loads that exceed the “limit loads” and possibly the “ultimate loads” and can result in structural failure. Certification limits do not consider the survivability of the structure under these extreme conditions.

I think that it is also important to understand that in order to begin to move any of the flight controls, there is what is known as a “break-out” force, or the force necessary to begin the controller movement - like the control wheel or rudder pedal. Once movement is started, there is a force necessary to continue to move the controller. But here we’re focused on the relevant control and control force is that necessary to move the rudder pedals. As you would probably suspect, the A300-600 rudder is hydraulically actuated – no surprise. In systems such as this, there is no direct feedback to the pilot. There is no “air load” on the control surface that the pilot can “feel,” so the system is built to provide an artificial “feel.” By way of comparison, a B767 (a similar sized airplane) at 250 knots has a breakout force of 17 pounds-feet (technical term) and the pilot would need to generate 80 pounds-feet to achieve maximum displacement – which in this airplane, is a bit over 3 and a half inches of rudder pedal travel and 8 degrees of rudder surface deflection. The A300-600 is noticeably different. Same circumstances the pilot has to use 22 pounds-feet to start the movement (breakout force) and 32 pounds-feet to get maximum rudder pedal travel (about 1.2 inches) and maximum rudder surface deflection (9.3 degrees). I don’t want to bore you with math, but the answer is that the A300 is over 7 times as sensitive as the B767; important enough to repeat … over 7 times as sensitive!! If you say this another way … the amount of rudder actually deflected for each pound of force on the rudder pedal above the breakout force is almost 9 times as much in the A300 as in the B767.

I said that the AA587 F/O was at the controls and therefore must bear at least some of the responsibility. I stand by that statement. However, I should also acknowledge that, in my opinion at least, pilots are not often enough trained on the FULL aerodynamic envelope, and how to manage that envelope, of the airplane they fly. My background and experience is heavily focused on education and training – and, no, I don’t believe that education is the fix-all remedy. However, education AND training, in combination with experience, is the basis on which being a pilot should stand. And like anything else, the content of that education, training, and experience has to be appropriate for what the person (here, the pilot) will be expected to face and handle professionally and completely.

I think that this F/O was probably one of those individuals who took a lot of pride in his airmanship – and I suspect he probably was a very good pilot. I think he was the type of person who constantly wanted to correct back to what he was trying to hold - and don’t we all, at least to some degree? I also think that he probably was a bit unsure of the proper way to deal with a wing-tip vortex encounter. I think he was not advised of, and very probably not trained on, the problems that can develop with maximum control input and repeated maximum control reversals. I think he was not aware of the sensitivity of the controls, particularly of the rudder, and how much rudder he was getting with very little force applied and how little pedal deflection generated full surface deflection.

I am also aware that the organizations that hire pilots are not interested in having their pilots spending their “on duty” time 90% in training and 10% on the line. But the question quickly becomes, do we train pilots for the minimum regulatory requirements (which all – or most anyway – airlines do today) and depend on the “good-naturedness” of the management to volunteer additional time in training … or do we increase the mandatory training requirements to an appropriate level – and what IS that appropriate level? I believe this is an important question – not just to be hashed around at the local bar at overnight stops. Serious, committed effort is necessary to determine what is required – absolutely required – and what is “nice to know” kinds of things. This is NOT an easily defined goal – but I know that as long as we continue to ignore it … we’ll never get to the answer!

Teldorserious

28th Sep 2013, 17:12

Rabbit - You are vastly overcomplicating the subject, where members in here think articulation substitues for knowledge.

Simply put a plane has design limitations, generally predicated on G force, as G force is a static number, given a varying airspeed. So 2 gs at 300 kts = 2 gs at 100 kts. Weight is weight. Certainly the input at 300 kts equal to the imput at 100 kts will provide more Gs.

But all things equal we are not talking about a plane flying through tops at Vmo with the pilots standing on the rudders, but a departure, slow speeds, well under Va. So a tail coming off at such slow speeds defies logic, unless, ofcourse, it's a carbon fibre/aluminum hybrid, that can't be Xrayed for fissures, but none the less, after the accident was fortified.

That said, the fallacy that one right rudder load for instance at a given acceptable load factor, then swinging the other way, at an acceptable load factor, has some mysterious exponential effect is pure baloney.

We aren't talking about building up resonance frequencies that need occilations on the order hundreds of hz, that typically happen well past Vne.

People can say all they want that test pilots can't account for every action that a pilot will possibly pull in an plane, but there is a reason why test pilots go up and slam everything up and down, back and forth, side to side, then bring it down for the engineers to see if the math was right.

Pure baloney to consider that any pilot moving the rudder three times will in any way exceed what a test pilot would do over thousands of hours, with much more rigourous flight imputs.

This is a simple case of carbon fibre mated with alluminum, resulting in Airbus fortifying the structure, after the fact, then trying to sell it to the authorties that anything can happen in a plane, at anyspeed, with any control input...effectivelly making many of your Vspeeds completly unreliable. This is just the recalibration going on in the industry right now where water isn't wet, the sky isn't blue, grass isn't green, and Va doesn't mean full deflection but rather, a worthless number, because you know, Airbus says so. The FAA has swallowed this hook line and sinker the same way they were convinced that an ATP wasn't required of prospective airline hires, putting 200 hour ab initio pilots in the cockpit 'because they have a special training program that meets or exceeds ATP requirements'.

Sure.

latetonite

28th Sep 2013, 17:20

Best one I read today.

Armchairflyer

28th Sep 2013, 17:52

But all things equal we are not talking about a plane flying through tops at Vmo with the pilots standing on the rudders, but a departure, slow speeds, well under Va. So a tail coming off at such slow speeds defies logic, unless, of course, it's a carbon fibre/aluminum hybrid, that can't be Xrayed for fissures, but none the less, after the accident was fortified.

That said, the fallacy that one right rudder load for instance at a given acceptable load factor, then swinging the other way, at an acceptable load factor, has some mysterious exponential effect is pure baloney (...) and Va doesn't mean full deflection but rather, a worthless number, because you know, Airbus says so.Boeing and IFALPA seem to differ:A structural design manoeuvring speed or Va is defined for evaluating aircraft structural design. At or below this speed, Boeing aircraft are capable of sustaining a single maximum deflection input to any control surface – elevators, ailerons or rudders (as limited by control surface limiters, blowdown or control stops). It should be noted that these control surface inputs are to be in one axis (i.e. not in combination) and do not include control input reversal or oscillatory inputs.
(...)
Boeing aircraft are not designed to a requirement of full authority rudder reversals from an "over yaw" condition. Sequential full or nearly full authority rudder reversals may not be within the structural design limits of the aircraft, even if the airspeed is below the design manoeuvring speed. There are no Boeing Procedures that require this type of pilot input. It should also be pointed out that excessive structural loads may be generated in other areas of the aircraft, such as engine struts, from this type of control input. Source and more on the subject: http://www.ifalpa.org/downloads/Level1/Briefing%20Leaflets/Aircraft%20Design%20&%20Operation/12ADOBL02%20-%20Use%20of%20rudder%20on%20Boeing%20aircraft.pdf , p. 2 & 4. They have one on rudder use in the Airbus, too: Aircraft Design & Operation Committee (ADO) (http://www.ifalpa.org/publications/briefing-leaflets/design-a-ops.html)

Clandestino

28th Sep 2013, 18:54

I don’t want to bore you with math, but the answer is that the A300 is over 7 times as sensitive as the B767; important enough to repeat … over 7 times as sensitive!! If you say this another way … the amount of rudder actually deflected for each pound of force on the rudder pedal above the breakout force is almost 9 times as much in the A300 as in the B767.True, but largely irrelevant unless someone provides the reference where it says a) rudder on any transport category aeroplane is normally used to control bank or b) that large, rapid and alternating control inputs have reasonable use on any aircraft. Go on, find any single circumstance on any single aeroplane where inflight rapid stop to stop movements in any axis make sense.

However, I should also acknowledge that, in my opinion at least, pilots are not often enough trained on the FULL aerodynamic envelope, and how to manage that envelope, of the airplane they fly.True, but largely irrelevant to case discussed as aeroplane was well within the envelope when it hit the wake and was chased out of it by inappropriate inputs on rudder pedals. It was not as if large slip oscillations was brought on by external factors so we need to teach pilots how to fight it. Better teach them how not to start it and while...

I don’t believe that education is the fix-all remedy... here it would just do the work.

And like anything else, the content of that education, training, and experience has to be appropriate for what the person (here, the pilot) will be expected to face and handle professionally and completely.If other aeroplanes, of the same type or different, were regularly falling out of sky with their tails torn off after hitting the wake vortex, then I might concede you have a point here and poor average line pilot is indeed ill-equipped to deal with the horrible rudder.

I think that this F/O was probably one of those individuals who took a lot of pride in his airmanship.According to the report, chapter 1.5.2.1. he was regarded as above average pilot so pride would not be misplaced. However, his misunderstanding that he was instructed under AAMP to use rudder unconditionally when faced with slight upset turned out to be fatal. Should we call this "incomplete airmanship"?

I think he was not advised of, and very probably not trained on, the problems that can develop with maximum control input and repeated maximum control reversals.Perchance because conventional wisdom considers such inputs completely useless and extremely dangerous so has just one thing to say about them: don't.

Simply put a plane has design limitations, generally predicated on G forceThat's just very, very small fraction of the limitations. BTW, limitations are not optional, you have to obey them all.

But all things equal we are not talking about a plane flying through tops at Vmo with the pilots standing on the rudders, but a departure, slow speeds, well under Va. Fin failure happened at 251 kt, Va was 270. 1 it takes a lot of subjectivity to put it under "well below Va" which is not to say it is safe to do whatever you want faar below Va. Large enough sideslip might produce extreme load thorough high Cl when rhoveesquared is lacking.

So a tail coming off at such slow speeds defies logicIt does only if your premises include completely wrong picture of lateral dynamic stability and aircraft-pilot coupling.

We aren't talking about building up resonance frequencies that need occilations on the order hundreds of hz, that typically happen well past Vne. No, we are talking about dynamically unstable yaw that reached extreme amplitude at frequency below 1Hz.

People can say all they want that test pilots can't account for every action that a pilot will possibly pull in an plane, but there is a reason why test pilots go up and slam everything up and down, back and forth, side to side, then bring it down for the engineers to see if the math was right.They might use full displacement. They might use rapid but they would never use large, rapid and alternating. They know better than killing themselves.

Pure baloney to consider that any pilot moving the rudder three times will in any way exceed what a test pilot would do over thousands of hours, with much more rigourous flight imputs. One has to weigh NTSB well explained, consistent and documented report against two words: "pure baloney". Tough one, eh?

This is just the recalibration going on in the industry right now where water isn't wet, the sky isn't blue, grass isn't green, and Va doesn't mean full deflection but rather, a worthless number, because you know, Airbus says soNo, such recalibration is just going on around anyonmous internet fora where people promote brazen falsehoods without any fear of consequences.

flarepilot

28th Sep 2013, 19:24

the NTSB did not unanimously agree with blaming the copilot.

if stomping on the rudder is bad, better put a placcard in front of the pilots

or make stronger planes

Blantoon

28th Sep 2013, 19:54

Blantoon, don't come in here with 4 posts and start giving the riot act. I am all ears if you have something to offer up.

If the tails of airliners come off under Va, then technically Va doesn't exist, or it needs to be lowered, or recertified with a placard that states.

'Pilots are to only use the rudder one way per episode to avoid catastrophic results'What does anyone's number of posts have to do with anything? :bored:

I would gladly offer something up, but since other people have already said anything I'd say far more eloquently than I could and you still won't put down that shovel; I think I'll refrain from wasting my time. :ok:

AirRabbit

28th Sep 2013, 20:33

Mr. Teldorserious – as I said earlier in this thread, throughout my tenure on this forum (and others) I’ve attempted to maintain at least some decorum in what I consider to be a rather professional discussion – as is typical of this forum. I don’t know your level of education – or the level of understanding you have – with regard to airplane construction and/or certification issues and, neither do you know mine. I have attempted to point you toward the regulatory requirements for the use of rudder in transport category airplanes. Yet you seem to be enamored with the concept of relying on what you “know” about airplane structures issues. With no attempt to insult you, I sincerely believe that regardless of the proficiency you now have in an airplane, if you were to broaden your knowledge of aircraft certification requirements and flight testing procedures, you would probably elevate that proficiency by a substantial margin. Of course, I have only the option of recommending that you do so … and, as to your comment on the rest of the participants on this forum “…thinking that articulation substitutes for knowledge…” I do not believe that to be true – even to the smallest level. Additionally, the “baloney” you believe I’m trying to force you to eat, may just be the “meat ‘n potatoes” on which you rely each time you say or hear “gear up.” In an attempt to get you to recognize the accuracy of your position, without causing you any potential embarrassment, I would humbly suggest you find an aeronautical engineer in whom you have substantial confidence and ask him/her to explain to you the potential results of applying rudder in the way the FDR assuredly shows was applied aboard AA587. Simplistically, if you ask this engineer his/her opinion of the results of a transport category airplane experiencing 7 control wheel reversals and 5 rudder pedal reversals, to the same magnitudes and at the same altitudes and airspeeds experienced by AA587 (which I presume you recognize to be well below Vne), all within 7 seconds, as recorded on the AA587 FDR, perhaps this engineer can explain the results better than I have apparently been able to explain. AND, should it be that you are, indeed, correct, I would you suggest you run, not walk, to the FAA and secure a consulting gig with them to rewrite their regulations for certification of transport category airplanes – as that would surely put some substantial coin in your pocket due to the significant amount of errors that must surely exist in those documents.

AirRabbit

28th Sep 2013, 20:39

Come on Clandestino – you know there is no one here saying that rudder should be normally used to control bank or that large, rapid, alternating control inputs have any reasonable use on any airplane, and certainly not me. The point is that such control applications make NO sense. And I agree that this particular airplane was well within the normal operations envelope and would warrant normal control inputs to control the airplane … in fact, this specific pilot did just that, and did so a mere 9 seconds previously to his initiating these obviously out-of-bounds over-control applications, when this encounter was no more serious than the one he had just transitioned quite successfully. How do I know that? Take a look at the FDR readouts and see for yourself. And, of course, teaching pilots the way to control an airplane throughout the entire envelope is entirely appropriate – and had that been accomplished, this might not have happened.

Also, I’m not sure what “horrible rudder” you are referencing … the one on the A-300-600? I have yet to see anyone say that this is a “horrible rudder.” Attempting to fix something that isn’t broken is like believing that gun control will stop killings due to guns. Guns don’t kill people. People using guns kill other people. But that’s a whole different issue. It wasn’t the rudder that came off the airplane … it was the entire vertical fin that was ripped off … and it was ripped off because of the misuse of the rudder control, accompanying the misuse of the lateral controls – don’t forget that when the ailerons are deployed, so are the roll-control spoilers – which add their own substantial influence into the mix.

I agree that airplanes around the globe are not falling out of the sky because of a loss of the vertical fin. I would love to think that this is due to the superb training received by the pilot groups. However, I tend to believe that at least to the same level of satisfaction you have for the training that currently exists, I believe it is uncommon to see encounters with wing-tip vortices that are handled the way this pilot did the second time. Rather, I believe most pilots deal with those encounters the way this pilot did on his first encounter with the vortex. The question should be – why didn’t he do the same thing he did previously?

Also, I believe you are jumping on the Advanced Maneuver Training that the airline was using. As I said some years ago, I have had the opportunity to see and fly a good share of that same training program – and I saw nothing that could be even remotely interpreted to be permission to use the rudder unconditionally when encountering the slightest upset. It is true that this program discussed the use of rudder – and it was introduced with no more fanfare or encouragement than were the elevator and ailerons. And, as I recall, the times when it made sense to use the rudder were those cases where the nose was uncontrollably pitched up, and the rudder could be used to bring the nose of the airplane back down toward the horizon. That is still true and still makes sense. In my experience with that particular program there was no hint that pilots were encouraged to use the rudder to address the recovery of a “slight upset.” However, the rudder is on the airplane for a specific reason – just as are the elevators and ailerons (including the spoilers). Recall the video of the B747 crash in the middle-east recently? The nose of the airplane was uncontrollably high – and it was apparent to me that the pilot was struggling to get it down … very likely on the rudder to help him do just that. Unfortunately, there was insufficient time and altitude for it to work.

dsc810

28th Sep 2013, 20:59

In respect of the questions/comment about all planes being unable to withstand the rudder being pedaled back and fro......or of it never being done.....and that no plane is tested for rapid reversals etc etc.

Take glider winch launches
If the speed goes too high on the launch you indeed do just that and pedal the rudder left and right. The a/c yaws significantly back and fro and the winch driver sees it as a signal to reduce the speed of the winch cable.
This is the official "too fast" signal on a winch launch.
So here you have substantial rapid alternating rudder deflections being regularly introduced when the a/c is flying near to the max manoeveing speed. Probably not stop to stop but certainly most of the way there.

I am quite well aware that transport aircraft are not in the same category as gliders but I'm just pointing out such movements are commonly used in one such class of aircraft.

Denti

29th Sep 2013, 04:50

That is still in use in the UK? It is expressively forbidden in Germany for the last 20 years or so. It resulted more than once in unsafe situations and accidents. If the speed is too high simply disconnect, but it might help of course to tell the winch driver beforehand that the speed is increasing, that's why we have mandatory radio communications, right?

Teldorserious

29th Sep 2013, 07:00

Must be fun to get an Airbus type...

'So what's the recomended rudder technique?'

'Well, um, you only push the rudder one way, for x amount of time, not too hard, not too fast, gently allowing it to come back to center. Set your timer...then when it dings, you are allowed to push it the other way, only so fast and hard.'

'How hard and how fast?'

'Well, you know, not too hard, or too fast. And just remember, your tail can come off at any speed. Yeah and forget about a higher Va with more weight..that doesn't apply either, especially on take off. By the way, the FAA says pigs can fly now, hell has just frozen over, girls are boys, red is blue, horses are really cows...are you taking notes?'

dsc810

29th Sep 2013, 07:43

@Denti
As listed in the UK's BGA's laws and rules: Part 9 - Signals
Page 3 of the Part 9 pdf file dealing with signals controlling a winch launch
"RP11: If the glider is being launched too fast, the pilot should yaw the glider from side to side with the rudder"
https://www.gliding.co.uk/bgainfo/lawsandrules.htm

Pilots are warned during training that before doing this they should ensure that they have 'unloaded the glider' by reducing the amount of back pressure they have on the stick if they are pulling back very hard at this point.

There is no radio communication that I have ever seen used between the glider and the winch during the launch. The only radio communication used is between between the launch point and the winch during the setting up of and the inititiation of the launch.

Owain Glyndwr

29th Sep 2013, 07:50

Teledor(lessthan)serious

Must be fun to get an Airbus type...Have you even read the Boeing contributions on this problem? you can find them here:http://www.ifalpa.org/downloads/Leve...20aircraft.pdf (http://www.ifalpa.org/downloads/Level1/Briefing%20Leaflets/Aircraft%20Design%20&%20Operation/12ADOBL02%20-%20Use%20of%20rudder%20on%20Boeing%20aircraft.pdf)

I would draw your attention to this extract:

The FAA/EASA have three rudder manoeuvre structural load design requirements, which the rudder and vertical fin must
meet in order to be certified3. These requirements are met for all airspeeds up to the design manoeuvring speed. In addition, newer
aircraft designs meet these requirements up to the design dive speed.
At a zero sideslip condition; the aircraft must be able to withstand a rapid rudder input to full rudder deflection. A Safety
Factor of 1.5 is then applied. This means the structure must have at least a 50% safety margin over the maximum load
generated by this manoeuvre.
Starting from a zero sideslip condition, the aircraft must be able to withstand a rapid rudder input to full deflection that is
held at full deflection until the maximum sideslip angle (over yaw) is achieved. The aircraft will exceed the maximum
steady state sideslip due to the dynamic response characteristics of the aircraft. A Safety Factor of 1.5 is then applied.
Starting from a maximum steady heading sideslip condition, the rudder is rapidly returned to neutral while maintaining
the sideslip angle. A Safety Factor of 1.5 is then applied.
During certification, Boeing does not flight test these exact conditions, but gathers flight test data to validate structural loads analysis.
This analysis, combined with ground structural load testing, ensures that the structure meets design requirements.

The FAA/EASA impose structural load design requirements in addition to these rudder manoeuvre requirements. These include
requirements for loads due to gusts, engine failure dynamics, and lateral control induced rolling conditions. Boeing aircraft vertical
fins can also sustain loads if the rudder is rapidly returned to neutral from the over yaw sideslip or the rudder is fully reversed from
a full steady state sideslip.
Note 3: These conditions are engineering design conditions that may be physically impossible to fly. Also to Fig.3 which shows the sideslip response to cyclic rudder movements and Fig.4 that shows the torque on the vertical stabiliser due to cyclic application of rudder.

Now you may think it amusing to slag off Airbus with cheap shots, but there are folks on this forum that actually take things more seriously than that. Let me remind you that the extract quoted above comes from Boeing. Note the careful wording that their vertical fins can sustain loads if the rudder is rapidly returned from over yaw sideslip or the rudder is fully reversed from a full steady state sideslip. No mention of the fin being able to carry the torque if the rudder is fully reversed at peak over swing sideslip. And all that relates to a single application and reverse of rudder. Look at the effect of cyclic rudder application on sideslip and you will (or should be able to) see that applying full reverse rudder at a peak of an enhanced overswing sidslip is going to produce loads well in excess of the structural capability. And that is for a Boeing aircraft!

In their equivalent document Airbus do not specifically mention an ability to withstand loads if the rudder is rapidly returned to neutral from the over yaw sideslip or the rudder is fully reversed from a full steady state sideslip, but the fact that the AA587 fin failed at about 2.2 times the limit load (as against the statutory 1.5 times) shows that their design has similar structural reserves to Boeing. [And that was the fin with the factory repair that you suggest might have been faulty - don't you realise that any aircraft repair has to be designed to be at least as strong as the original structure!]

I can only concur with Air Rabbit that you might benefit from some serious study of aircraft design and construction.

BTW, you did not respond to my request for identification of the source of your original remark re FAA changes to Va. There was a long debate about the definition of Va in an earlier thread. Perhaps you should also read Keith William's contribution in #21 of the Va Manoeuvring thread

Denti

29th Sep 2013, 08:23

@dsc810 quite off topic now, but yes, in times gone past the same signal was used over here, but it was discontinued as it was deemed extremely unsafe and isn't allowed anymore (although some of the older crowd might still use it, if somethings happens insurance won't pay a thing then). Radio communications are required between winch and launch point as well as between launch point and glider, however every club i flew with had an additional radio on the winch to monitor the glider fields frequency for exactly that kind of command as it is of course faster than communication via the launch point. Current requirement for overspeed is to disconnect and depending on height land back or straight ahead.

And of course certification requirements between gliders and airlines are vastly different, so on the rudder issue, which is used much more often in gliders, it is probably something about apples and oranges.

BBK

29th Sep 2013, 08:54

It seems some posters on here have been drinking from the fountain of knowledge and some only gargled!:E

Air rabbit, Owain G et al

Some interesting info so thanks for posting. My vague recollection, from reading Flight International, was that the problem was largely due to the large rudder input and then the REVERSAL afterwards.

From a line pilot's point of view I cannot envisage why the FO would have thought that such inputs were necessary. No criticism implied- there but for the grace of God etc. Apart from an engine out condition one doesn't touch the rudder in normal ops. In an extreme attitude then of course it may help to use rudder eg high bank angle with the nose yawing below the horizon. I believe that was an example described in the American Airlines training video that I watched many years ago. That video was withdrawn from use after this crash.

The other point I have had drummed into me is that with powered flying controls one has to treat such controls with more than a little respect. With the rudder in particular it is a large control surface and and so, for example, when cycling the rudder on the pre take off checks one must do so SLOWLY!

BBK

roulishollandais

29th Sep 2013, 09:22

To go back to your original post, could you please point me towards the actual FAA change to Va? I failed to find it.I failed too. Teldorserious, could you help please?

Thank you dsc810. Gliders are not built like airlines, but it is assumed that starting piloting with gliders is a good pedagogy. As we learnt it from AA587 wrong practices were accepted from the community of pilots. We have to change now these false ideas built on very particular situations with bad solutions : Learjet dutch roll or communication between glider and trailer. Didactic is important. We know that in critical situation our brain is regressing to what we learn first. How we learn to fly is still coming out after thousands of hours. What you have well learnt in initial formation is for ever. Poor initial training is expensive and dangerous.It is important to give effect to accident reports like AA587 in pedagogy.

Chris Scott

29th Sep 2013, 09:55

This has been an interesting and illuminating discussion, thanks!

Quote from tdracer:
I don't seem to recall anyone ever claiming that the 707 airframe wasn't robust.

When I did my base training with AA at DFW in 1975, I was surprised that no attempt was made to demonstrate dutch roll characteristics and recovery at altitude, even though the a/c was equipped with only one yaw damper. (BTW, I'm not suggesting that dutch roll recovery by the pilot would involve any use of rudder.) Four years earlier, my VC10 conversion had included several full demonstrations (up to about 40 degrees of bank) and recovery. The VC10 has(d) 3 independent rudders, each with a yaw damper.
One possible interpretation was that the a/c was not inclined to serious dutch roll at altitude - we all know that it would on the approach. On reflection, I'm wondering if the B707 airframe, specifically the vertical surfaces, may have been merely adequate for the regs? Has anyone got a copy of Davies to hand?

Quote from flarepilot:
that plane would still be flying if it had a rudder limiter based upon speed. at low speed full throw, at higher speeds less throw.

It has precisely that.

Clandestino,
Your posts are always well-informed, but could I respectfully suggest that you might resist the temptation to nit-pick the statements of those posters with whom you are broadly in agreement, and that you allow for the context in which they are made, and the audience? I'm sure you don't mean to sound arrogant..

Quote from Teldoserious:
Must be fun to get an Airbus type...

Indeed it is! The OP has made some unsupportable assertions (not all as cliched as the above), and in doing so has done us readers a favour by provoking the authoritative contributions of AirRabbit, Owain, and some others.

SMOC

29th Sep 2013, 10:27

Re-upping my CFII was pretty funny...

Teldorserious, out of interest what A/C ratings do you hold or have held?

I gather you've never flown an Airbus, what about Boeing?

Brian Abraham

29th Sep 2013, 11:27

He has no ratings what so ever. He has appeared under numerous identities over the years, and always wears his ignorance on his sleeve.

flarepilot

29th Sep 2013, 11:54

john smith

just about every plane I can think of in the transport catagory has the admonishment that the pilots operating handbook assumes the pilot is an experienced and knowledgeable pilot and does not hand hold the novice.

shutting down the engines in cruise is generally recognized as contrary to maintaining altitude

scanning the instruments is generally recognized as a requirement for precise flying...

an experienced pilot knows that.

but what us experienced pilots didn't know was that using the rudder in a certain way WOULD CAUSE THE PLANE TO FALL APART.

I am of the generation that had it drilled into them BY THE FAA in its approved methods that structural failure wouldn't occur below certain speeds with full control throw.

(not unless their was previous damage to the plane)

In the modern cockpit there are some odd placcards...one I mentioned was about limiting control throw to HALF above 40,000'

many of us go to work every day in planes that have placcards saying you can't do a Catagory 2 ILS without proper training and operating equipment...now most of us still think that one is out of place...BUT ITS STILL THERE.

A placcard describes something unusual about the airplane, it is akin to the pilots operating handbook. Even a short paragraph in the airbus POH saying not to screw with the rudder would have done the trick

OF COURSE, who would buy an airplane that has a placcard or POH statement like: IF YOU SCREW WITH THE RUDDER THE PLANE WILL< REPEAT WILL< FALL APARt and KILL EVERYONE.

sorry john smith...if you knew the plane had this problem and you didn't tell all us other pilots, shame on you.

I just wish I had copies of all those books and tests I've used over the years with statements about what controls, what speeds, etc , all FAA approved.

DP Davies would have had something to say.

Oh, by the way...getting ''locked into " wake turbulence is something we train for...and it can be a bitch ...can't anyone conceive that the wake was bad enough to start a whole cycle of events that ended up showing the weakness of this plane?

I am reminded that there was a dissenting opinion from an NTSB member about the probable cause and the tail had previous , unknown or unreported damage.

makes one think

oh, and an A310 lost a piece of its rudder on a different flight...hmmmm

makes one think

JammedStab

29th Sep 2013, 12:52

oh, and an A310 lost a piece of its rudder on a different flight...hmmmm

makes one think

I think that it is a separate issue. Losing a rudder is a lot different than losing the entire fin which happens to take the rudder with it.

The partial rudder thing was due to some sort of disbonding I believe.

HazelNuts39

29th Sep 2013, 13:07

A placcard describes something unusual about the airplaneMaybe that's the reason there is no placard in transport airplanes explaining use of rudder?

fantom

29th Sep 2013, 13:23

HN, exactly.

Denti

29th Sep 2013, 13:26

Isn't it somewhat tiresome discussing stuff with two different SSG personae in one thread?

Teldorserious

29th Sep 2013, 15:28

Since the trolls(Brian and Denti) have jumped in, the thread derailed. I'm out.

If the Airbus can't take a rudder back and forth, so be it. You can believe that all planes are like this, completely nullifying what us pilots do every day in training, in x winds, in single engine ops, or day to day flying, stepping on the rudders all day long, back and forth, at all sorts of speeds. Still here.

misd-agin

29th Sep 2013, 15:35

The sad part is some still havn't learned the lessons from this accident. Boeing has pages of text on what is, or isn't, acceptable rudder input.

"If you believe that all planes are like this" - we're talking about commercial jet aircraft. What a/c are you talking about? What commercial jet a/c can you swing the rudder back and forth, stop to stop, with no cause for concern?

Teldorserious

29th Sep 2013, 15:53

The lesson is that Airbus made a crappy tail that couldn't be inspected for fatigue, and it did fall apart under conditions that many of us have exceeded in other aircraft, by orders of magnitude, every day in turbulance, upset recoveries, and normal training regimens.

pattern_is_full

29th Sep 2013, 17:10

I've got a technical question (this being the Tech Log forum) that I haven't seen addressed, even in the NTSB report.

What sequence of effects or factors led to AA587 then losing control and crashing after losing the vertical stabilizer?

Yeah, yeah. I know. "Duh! The tail fell off!" Except that aircraft (even large jets) have lost their vertical stabilizers without subsequently crashing: http://www.murdoconline.net/wordpress/wp-content/uploads/2011/04/b-52-no-vert.jpg

I'm figuring the probable effects were:

- abrupt shift to a nose-down cg with the loss of the stabilizer's weight from the tail.
- "snap yaw" in reaction to the loss of the rudder's yaw force in the opposite direction.

BTW - I don't mean to imply that the AA crew could have saved the aircraft. They had little altitude or time and were in an already confusing situation. The crew of the B-52 pictured were test pilots intentionally trying to identify structural weaknesses. So they were at a safe altitude, and expecting (more or less) something to break.

Armchairflyer

29th Sep 2013, 17:20

AFAIR, according to tests after the AA587 accident the "crappy Airbus tail" did exceed the required and specified strength specifications by a considerable margin. A more valid point of Airbus-related criticism was the sensitive reaction of the rudder pedals, translating even very small pedal movements into considerable rudder deflections at higher speeds. And indeed there was apparently some widespread confusion regarding the limits represented by Va, including the FAA itself.* But all this has nothing to do with the tailfin strength or accessibility of the Airbus vertical stabilizer.

* Cited source: AA587: The Perils of Flying by the Book | Flying Magazine (http://www.flyingmag.com/safety/accident-investigations/aa587-perils-flying-book?page=0,0)

@pattern: the B52 on the picture still has an (albeit small) remaining piece of vertical fin that stabilizes the airplane with regard to yawing movements. Without any fin and the resulting weathervaning tendency, AFAIK no airplane can be controlled in flight.

Owain Glyndwr

29th Sep 2013, 17:44

@pattern

I'm not sure about this but I believe that the B52 didn't have any hydraulics in the vertical stabiliser - I'm sure someone here will correct me if I am wrong there.
When AA587 lost its fin it also lost all hydraulics since it was supplied by all three systems. Consequently there was no aerodynamic control of any sort available whereas, if I am right, the B52 at least had elevators and ailerons.

flarepilot

29th Sep 2013, 18:26

DEAR JOHN SMITH...

I see the problem...you don't understand that thousands of properly certificated FAA approved pilots did NOT KNOW THAT STOMPING ON THE RUDDER would cause the plane to fall apart.

thousands of us learned that if you were at or below Va and applied full control movement the plane would not fall apart.

it was on countless examinations and in FAA literature of the time.

Even while flying other planes, that had rudder LIMITATIONS and rudder limiters WE (PILOTS) were required by the FAA and OUR AIRLINES to memorize and display knowledge of limits imposed by design of the plane we were flying.

I can still explain how the rudder limiter system works on douglas systems and boeing systems and that if the limiter system fails we have to KNOW NOT TO USE TOO MUCH RUDDER ABOVE CERTAIN SPEEDS.

What the properly certified airline, training program, and pilots who were involved in the A300 inflight breakup DIDN'T know then is what you claim to have known all along.

Hence my advice about a placcard or a POH write up.

I'm glad you know...but I didn't and a whole airline didn't and the FAA didn't know.

But you knew.

yeah, right.

now we know...and maybe that's why the airbus is so junior at some airlines.

tdracer

29th Sep 2013, 19:41

Here is a cut and paste out of a Boeing 777 AFM:

F L I G H T C O N T R O L S

Avoid rapid and large alternating control inputs, especially in
combination with large changes in pitch, roll, or yaw (e.g. large
side slip angles) as they may result in structural failure at any
speed, including below VA.
I'm pretty sure all Boeing AFMs have that same statement. It didn't use to be there - it's addition was in direct response to the A300 AA587 crash.

Do you really need a placard to remind pilots not to do something that the AFM tells them not to do?

Teldorserious

29th Sep 2013, 19:54

I agree with everything Flare said.

You see some of us teach this stuff, some of us have been getting ratings, some of us have been getting types, some of have been going to school every year and some of us have had to teach and regurgitate the definition of Va now for some time.

It's absolutely full out of deception for peeps in here to say after the fact, after the crash, after the FAA redefines Va, to say ..

'Yeah, well, you know, when WE flew, we never thought that Va, full scale deflection and all that meant anything...because you know...we didn't trust the test pilots, or the manufacturers to give us a speed that we could trust to hit a top, come out upside down, do a recovery any which way...because you know...WE knew all along that three pedal imputs in an Airbus would take the tail off.'

Meanwhile, the rest of us are pounding on the rudders for single engine work, side slips, x winds, upsets, stall recoveries, sometimes bad spin recoveries...and yes in twins, tprops and jets, because you know, pilots should know this stuff..and believe it or not they do upsets, stalls, and recoveries in airlines...right? Or do all you guys just get a little beep and push the nose over and call it good.

Either flare and I are getting putt on by a bunch of kids in here or the airline guys are just following what they are told.

This year Va is x, next year y. This year CRM is great, next year crap.

Maybe because its on me to pull the levers back when things get bumpy I have to know this stuff.

Fantome

29th Sep 2013, 20:20

whether or not those who are doing it as in at work at the front end heed these savvy words
from the coal face and inputs Teld, please keep it up. you have a large readership and no mistake

BTW how come that chinese 747 that stalled and only recovered feet from the briney off NW america all those years ago not serve as an example to all plane makers in getting it right on the drawing board and making them Boeing tough?

BBK

29th Sep 2013, 20:25

Teldoserious

I think some of us airline guys are merely trying to say that large rudder inputs, other than for assymetric yaw conditions, are pretty much unheard of. Possibly in an "upset" condition if it helps to pick up a wing and/or prevent further yaw. I'm not an expert but I've never heard it suggested as an appropriate response. In a vortex encounter I'd expect to use aileron primarily.

Light aircraft may need an appropriate rudder input and I've spent a fair amount of time teaching "co-ordinated" controls. If you're teaching in an aircraft with barn door ailerons that are prone to aileron drag then it's essential. Perhaps that is where your confusion is arising?

tdracer

I suspect all the Boeing FCOMs were amended after the AA crash.

Armchairflyer

29th Sep 2013, 20:42

Cannot say anything for commercial jet aircraft and will readily stand corrected as always, but apart from the (AFAIK rather controversial) "falling leaf", I cannot think of any manoeuvre with oscillating hard rudder inputs. And frankly, even if at speeds well below Va in the spamcans I sometimes fly (let's say at 80-90 KIAS), the idea of giving several alternating full rudder inputs just feels wrong and abusive.

Teldorserious

29th Sep 2013, 21:40

BBK or anyone with Bus experience....

In a bus, can a pilot at say a 200kts, aerodynamic forces be damned, step on a rudder to full stop, and the resulting action in the tail is that the rudder slammed hard over would result in a resulting bang or resonance in the fusilage because the rudder slammed over that hard on the vertical stab?

IF that is the case, that would answer something.

AirRabbit

29th Sep 2013, 21:57

Mr. Teldorserious:

May I ask that you clear up something that is bothering me? Am I reading your posts correctly by understanding that when you started flying you were trained, and trained well, but were never trained, at any point in your career, to NOT apply full rudder in either direction – and specifically were NOT trained to never move any flight control from its hard-stop in one direction to its hard-stop in the opposite direction as fast as you are able? Further, am I understanding you to say that it is because of this absence of training in this specific area, you have determined independently that it must be permissible to apply full flight control input, for any flight control, to its mechanical or aerodynamic limits, in either direction, and then to rapidly move that control in the opposite direction to the opposite mechanical or aerodynamic limits? Or are you saying that you were specifically trained, and if not trained, at least told, that moving this control to one of its directional limits and then rapidly moving that control to the opposite limit, was an acceptable behavior in whatever airplane you were currently training to fly?

I ask this specifically in light of the fact that the AA587 accident airplane FDR readouts clearly show that this is precisely what the F/O did. And in light of your answers to my questions above, we might be able to discern that you are convinced that the accident resulted from inappropriate actions by that F/O or you are convinced that the accident resulted from operating an airplane that was built and certificated in accordance with grossly inadequate standards.

Thanks in advance for your clarifications.

flarepilot

29th Sep 2013, 22:26

Am I to understand that you have never gone to the mechanical stop in any plane? Did someone tell you never to go to the mechanical stops or from mechanical stop to mechanical stop during your control checks?

Am I to understand that you have never landed in a crosswind which required full control to the stop in order to maintain control?

Am I to understand you were told you could not go to the mechanical stop ?

I've been saying over and over that there are certain planes that have limiters (mechanical or lock outs) and that they are well covered in POH and in FAA examinations. I've mentioned placcards till I was blue in the face.

BUT THE FREAKING A 300 didn't have that now did it? Anyplace in the A300 manual from the 1990s that said: DO NOT USE FULL CONTROL THROW OF ANY CONTROLS STOP TO STOP?

IF SOMETHING IS OBVIOUS, does it need saying...YES...and if something is not obvious it really needs saying.

In one transport jet I flew, we could not take off unless the rudder limiter light was working properly and if it failed in flight we had a MANDATORY MEMORY ITEM of which speeds to use full or less rudder.

DID THE A300 have that ? I doubt it.

Maybe the designers assumed something about the A300

and when you ASSUME, you make an ASS out of U and ME

nope, don't blame the copilot...there may be dozens of men to blame, but he didn't have a placcard, or a POH limitation, or hours of lecture and examination.

But I will say this...when I first saw the A300, many years ago, the first thing I THOUGHT TO MYSELF WAS...GOSH THAT TAIL SECTION LOOKS WEAK.

But you see, that is just what I saw and didn't have a POH, placcard, or a lecture to tell me anything.

you don't have a second chance at a first impression.

Clandestino

29th Sep 2013, 22:53

And, of course, teaching pilots the way to control an airplane throughout the entire envelope is entirely appropriate – and had that been accomplished, this might not have happened.Could be true but I still don't see how "Don't ever rapidly cycle any flight control on any aeroplane under any circumstances" is envelope dependent. IMHO it is far more basic than teaching the pilots how to recover from the corners of the envelope.

However, I tend to believe that at least to the same level of satisfaction you have for the training that currently exists, I believe it is uncommon to see encounters with wing-tip vortices that are handled the way this pilot did the second time.While I'm far from being satisfied with the level of training that currently exists, I do resent the attempts to draw the syllabus even further along the wrong way. Of course it is uncommon to see wake vortices handled the way it happened on AA587, most folks use wheel/stick to roll the aeroplane. That rudder is to be used to induce roll only when wheel is not enough should be basic airmanship which lead us to...

Also, I believe you are jumping on the Advanced Maneuver Training that the airline was using. ...my opinion that the biggest problem with AAAMTP was the third "A" - advanced. I'm not suggesting that program was problematic by itself. That flying folks lacking some basic understanding are quite capable of misapplying potential life saving action and turning it into lethal one was clearly demonstrated. I really don't know whether it's better to tailor the program to dumbest common denominator and have nothing advanced in syllabus lest it be misunderstood or insist on higher selection and training criteria so every pilot can get to grips with advanced concepts.

In ideal world choice would be easy.

That is still in use in the UK? It is expressively forbidden in Germany for the last 20 years or so.Could be no one was killed in UK through getting way too much yaw at too low speed on a winch... yet.

As we learnt it from AA587 wrong practices were accepted from the community of pilots. Wrong theories, not practices. Until AA587 no one tried to put "whatever I do with controls below Va won't kill me" to test so misunderstandings about Va were widespread but didn't increase the death toll until that fateful day.

We know that in critical situation our brain is regressing to what we learn first.Well then pilots mustn't have brains because in critical situations they mostly apply what they have learnt last.

What you have well learnt in initial formation is for ever.So if it's wrong, one is doomed? Fortunately it doesn't work like that in real life. It can be forgotten, rejected , expanded upon or whatever. It is likely to influence one but is far from being set in stone.

It is important to give effect to accident reports like AA587 in pedagogy.Too complicated for beginners and totally unnecessary to go through whole of it. "Don't cycle your anything and don't pick the wing with the rudder if there's enough aileron" would suffice.

I am of the generation that had it drilled into them BY THE FAA in its approved methods that structural failure wouldn't occur below certain speeds with full control throw.Heck, I could pump up my number of posts just by repeating "People with scant understanding of dynamic stability should not be overly assertive around here" ad nauseam.

OF COURSE, who would buy an airplane that has a placcard or POH statement like: IF YOU SCREW WITH THE RUDDER THE PLANE WILL< REPEAT WILL< FALL APARt and KILL EVERYONE.Today everyone in the airliner market is compelled by law to buy such contraptions. Not with the exact wording but close enough.

can't anyone conceive that the wake was bad enough to start a whole cycle of events that ended up showing the weakness of this plane?Just those who haven't a) read the report b) understood the report c)both.

I am reminded that there was a dissenting opinion from an NTSB member about the probable cause

And I'll copy-paste the relevant part it for you once again:

To elevate the characteristics of the A300-600 rudder system in the hierarchy of contributing factors ignores the fact that this system had not been an issue in some 16 million hours of testing and operator experience—until the AAMP trained pilot flew it.

The lesson is that Airbus made a crappy tail that couldn't be inspected for fatigue, and it did fall apart under conditions that many of us have exceeded in other aircraft, by orders of magnitude, every day in turbulance, upset recoveries, and normal training regimens. Just plain lie.

I see the problem...you don't understand that thousands of properly certificated FAA approved pilots did NOT KNOW THAT STOMPING ON THE RUDDER would cause the plane to fall apart.That indeed was a problem... fixed now.

I'm pretty sure all Boeing AFMs have that same statement.Airbus, ATR and Bombardier too.

BTW how come that chinese 747 that stalled and only recovered feet from the briney off NW america all those years ago not serve as an example to all plane makers in getting it right on the drawing board and making them Boeing tough? If it stalled nearer the TOC than TOD, outcome would be pretty different.

Teldorserious

30th Sep 2013, 00:06

How about a hypothetical conversation with an Airbus test pilot -

'Did you slam the rudder back and forth when testing the bus?'
'Yes, that's what test pilots do'
'Do you do it at different speeds'
'Yes, that's what test pilots do'
'How did you determine Va'
'We flew to the limits of mathematical fatigue to see if the math was right, examined the structure. Adjusted the numbers, butressed up the airframe if needed, that's what test pilots and engineers do'
'Do you think a left, right, then left application of rudder would take the tail off'
'If it did, then all the Airbus test pilots would be dead or better skydivers.'
'So what is the problem then?'
'Fatigued structure, bad engineering, a bad landing? Went through severe turbulance too many times, bad manufacuring that day, they put that tail on the day before Christmas. Temp issues with carbon fibre, the alumimum condensed moisture in there, maybe it's like the Alaska jack screw deal, mechanics signed the tail inspections off with out getting on a ladder, hydraulics too strong calibrated incorrect, slamming stops, terrorism, it did happen with an engine out...two failures at the same time...what are the odds of that?'
'so do you think the pilots screwed up?'
'Well what do you think an airline pilot could do departing on climbout, standard engine out procedure in a big whale that I couldn't do with an empty plane, both of us in parachutes over a test area trying to break the plane?'

flarepilot

30th Sep 2013, 00:26

hey clandistino

you quoted the ntsb and the 16 million flight hours stuff

tell me, how many flight hours did the boeing 737 have before the rudder hardover that caused the crash near pittsburgh, pa?

I never respected people who quote other people in their replies...

the substance of pprune is pilot experience...i'd much rather hear a narrative of what you have observed in flying instead of pasting quotes and commenting upon them

hey teldorserious...isn't it funny how all the people defending the bus might not have been old enough to hold an atp when the accident happened?

JammedStab

30th Sep 2013, 00:26

A lot of talk about Va but in reality....who knows what their Va is on the airliner they fly. On the one I fly, it is a continuously changing number and it has been the same on the last several that I have flown. Vb is memorized of course in knots and mach and it is less than Va for my type.

I'm sure someone will pipe up and scold me for not having all the Va speeds memorized but I suspect that there is a high percentage of competent pilots in airliners that are the same.

Try asking your other flight crewmember at a particular altitude what their present Va is and see if they know, In fact, I will ask right now to all, what is your Va at 5,000 feet ASL at max landing weight.

galaxy flyer

30th Sep 2013, 00:36

SSG 3.7

Give it up, the Airbus experimental test crews did not such "slamming" of the flight controls because they are professionals, not frustrated "free lancers" with a CE-500 rating, th certification criteria requires not such "slamming" because to do so is very hazardous. Not FAR 25 certified plane cn stand rapid, full throw control reversals. Neither can many military planes. The C-5 tail was subject to very elevated fatigue levels due to air refueling training missions; a BUFF lost its rudder in mountain wave; a KC-135 was nearly torn apart after a wake encounter during Desert Storm. If you fly like you write, I don't want to be near you. Please submit NOTAM prior to flight.

GF

Teldorserious

30th Sep 2013, 00:37

Flare - Probably more suprising is how many have been flying airliners since the Wright Bros and just believe everything they were told.

But to your point, I got into it years ago with a guy at a CFII renewal. He's telling me he's a pilot at United...telling me that they got an 'illegal' IFR clearance and such, that's why they blew an altitude or flew through some restricted area or some nonsense.

Ofcourse I ask why they accepted the clearance and flew it, ect...and he got flustered...argumentative...

Well later on, a guy pulled me off to the side and said 'yeah, don't worry about that guy...he got 'in' with United by writing manuals for them, as a way to get a pilot job, he's got 800 hours...now.'

Now this is before the internet, so there is just no way to know who we are talking to here and what their experience level is. I just know if I you and I were ferrying a BUS, hit turbulance, flew under Va...what are we supposed to do, leave our feet on the floor? What if we had an upset, stall recovery, windsheer....sorry no rudders for you...

Galaxy - Picture yourself in that 747 at Bagram, the plane rolls one way and all you got is rudder, then it rolls the other...oops...can't push the rudder the other way to save the flight...because Airbus says you can't? Do you realize with your logic, you would be dead in that scenario? I guarantee after all your blather under that scenario your rudder would look like a humming bird outside my window unless you truly were a robot kool aid drinker more interested in saving the tail then saving the plane. Well who knows if you get into a stall you will have time to pull out your sops manual or call dispatch for advice. Maybe we can put a time machine in your plane, to create some temporal distortion bubble around your plane, so you can sit there, pushing the rudder one way...nope that didn't work...hit stop, count to ten, yep...ok, NOW I can hit the other rudder, see if that works....because you know...Airbus told us not to wiggle the rudder too much.

galaxy flyer

30th Sep 2013, 00:40

I hope you don't use the rudders in turbulence, at least, in a jet. Sideslip is a no-no in swept wings. Read your D.P. Davies Handling the Big Jets.

GF

AirRabbit

30th Sep 2013, 01:05

Wow! So much for civility, eh? Geeze … and we’ve never been introduced, either. OK.

Am I to understand that you have never gone to the mechanical stop in any plane? Did someone tell you never to go to the mechanical stops or from mechanical stop to mechanical stop during your control checks?
Just for clarification … “going to the mechanical stop” is not the problem … going from one mechanical stop to the opposite mechanical stop during pre-flight control checks is not the problem … it’s during flight, after having reached a mechanical stop in one direction, THEN rapidly going to the opposite mechanical stop, and then reversing that to the original mechanical stop, over and over and over … that is what presents not only a problem, but a significant problem.

Am I to understand that you have never landed in a crosswind which required full control to the stop in order to maintain control?
No, please do not understand that … and while I’m not sure what brought you to ask … but you should know that if I ever attempted to land in a crosswind that would require full control to the stop and then full control to the opposite stop and then full control to the opposite stop … and continue … I’d never again drink that much before I went to sleep … those kinds of nightmares are not worth it.

Am I to understand you were told you could not go to the mechanical stop ?
Am I going out on a limb here by thinking that you’re describing going to the mechanical stop while airborne – with the presumption that you believe that certainly no one would ever expect their student’s to read and understand the regulations under which the airplane they’ll be flying was certificated? Well, on every airplane I’ve ever flown operationally, someone, someplace, made sure that I understood that there would be minimal times when full control application would EVER be required – in any axis – and it doesn’t take the proverbial “rocket scientist” to understand the regulations under which airplanes are certificated. I even included in an earlier post, the specific language contained in the US regulation (§ 25.351 Yaw maneuver conditions, for your reference) - where it clearly describes returning the control application to NEUTRAL after application to the control stop limit. Am I to understand you’ve never read the rules used to certify the airplanes you’ve flown? And, before you ask, yes, I’ve flown a lot of different airplane types (more than I care to list here – no brag – just a lot of work) and the A300-600 is NOT one of them … in fact, my experience on Airbus equipment is limited to the A320 and A330 – and then only a few trips around the pattern and some “up and away” flight control tests in each. But, by that time, I really don’t recall if I was specifically reminded as to how to handle the control application – as it wasn’t really necessary.

Oh, by the way … does everyone require a note someplace or a placard installed for all of the actions that we are NOT to undertake? Are there “Do not eat the contents” statements on Laundry Detergent, or automotive oil, or gasoline?

I've been saying over and over that there are certain planes that have limiters (mechanical or lock outs) and that they are well covered in POH and in FAA examinations. I've mentioned placcards till I was blue in the face.
BUT THE FREAKING A 300 didn't have that now did it? Anyplace in the A300 manual from the 1990s that said: DO NOT USE FULL CONTROL THROW OF ANY CONTROLS STOP TO STOP?
IF SOMETHING IS OBVIOUS, does it need saying...YES...and if something is not obvious it really needs saying.
As long as we’re swapping questions … are you saying that you’ve never read or if you read you don’t understand the regulations under which the airplane you’re flying today was constructed and certificated?

Also, are there are any placards on the airplane you currently fly that tell you what the maximum aileron control limits are … or the elevator limits. What about maximum gear lowering speed? … or maximum flap extension speed? … or anything like that? No? Would you feel comfortable in kicking the rudder on your airplane from stop to stop to stop to stop … Or, perhaps you could enlighten us as to the kind of questions asked of you by the FAA for the airplane you’re currently flying that ensures them that you understand what, if any, limits there are for your airplane? And by the “all CAPS” comment, I would guess that all of the airplanes you’ve flown had placards or notes in the Flight Manual telling you what NOT to do? How about flying the airplane upside down? Is that in your manual? No? How often to you do that?

In one transport jet I flew, we could not take off unless the rudder limiter light was working properly and if it failed in flight we had a MANDATORY MEMORY ITEM of which speeds to use full or less rudder.
DID THE A300 have that ? I doubt it.
Really? What speed were you supposed to hold if you wanted to use less than full rudder?

Maybe the designers assumed something about the A300
and when you ASSUME, you make an ASS out of U and ME.
Well, IF the A300 designers assumed something about the A300, they failed in their attempt when they were thinking of my involvement – so … please feel free to speak for yourself on that topic.

But I will say this...when I first saw the A300, many years ago, the first thing I THOUGHT TO MYSELF WAS...GOSH THAT TAIL SECTION LOOKS WEAK.
But you see, that is just what I saw and didn't have a POH, placcard, or a lecture to tell me anything.
Is that right? Really? Perhaps you could consider going to work for one of the major airplane manufacturers … in that they wouldn’t have to go through all their research, testing, and any re-design issues … they could simply ask you.

you don't have a second chance at a first impression.
Again … really? What about a first chance at a second impression … or is that overly deep?

bubbers44

30th Sep 2013, 01:14

AirRabbit

30th Sep 2013, 01:16

How about a hypothetical conversation with an Airbus test pilot

The only test pilot that would qualify to be involved with the hypothetical conversation you propose would be ones that have been drawn on multiple-layers of photographic film and speak in a tone reminiscent of Donald Duck. Beyond that, a written response certainly isn’t warranted!

bubbers44

30th Sep 2013, 01:20

Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.

AirRabbit

30th Sep 2013, 01:31

Just fly like you were taught over 30 years ago. In the last dozen years button pushing seems to be the new way. AF447 is an example of how well that works. As far as rudder usage in wake turbulence it is a roll problem, not yaw so the AA FO probably used very little rudder no matter what that captain said. The NTSB doesn't always tell the truth.

I’ve known members of the NTSB and their technical staffs for more than 3 decades now, and they’ve always provided the material (for anyone to read) from which they’ve drawn the conclusions they publish. I do recognize that there are times when their conclusions seem to ignore some of the materials they include in their official reports – and I cannot (nor do I intend to) explain those kinds of shortcomings. However, in this specific case, the FDR is pretty clear that either the Captain or the F/O in the cockpit managed to repeatedly displace both the rudder pedals and the aileron control to (and in some cases it would seem, beyond) the mechanical limits. The A300-600 does not have reversible controls – meaning that if you move the aileron or the rudder surface on the airplane – there is NO movement of the respective cockpit controller. But this airplane DOES record the cockpit controller movements – all three axes, and the rudder pedal movement corresponds exactly with the rudder surface displacement. And to avoid repeating myself (see my previous posts) there is little doubt that someone in the cockpit made 7 aileron reversals and 5 rudder reversals within that 7-second time frame. There is nothing on the CVR to indicate that the Captain was assuming control of the airplane – and, in fact, after the first wing vortex encounter (which, the F/O handled quite professionally and correctly, by the way) the Captain asked the F/O if he had encountered a “bit of turbulence” and it was the Captain on the radios after the initial application of power for takeoff.

AirRabbit

30th Sep 2013, 01:39

Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.

My question would be – how did they know that the rudder was being deflected? Unless Airbus has changed the control philosophy to one of reversible controls – displacing the rudder surface will not affect the positioning of the rudder pedals in the cockpit. If the pedals in the cockpit were being deflected, again presuming Airbus has not gone to reversible controls on this airplane, must be due to some anomaly in the rudder “feel” system. Of course that isn’t good and should be noted and repaired. In the accident airplane both the rudder surface AND the rudder pedals were deflected – meaning that one of the cockpit occupants must have been “on” the rudder pedals and commanded the rudder surface position.

bubbers44

30th Sep 2013, 01:49

Whatever! That is what happened.

bubbers44

30th Sep 2013, 01:57

Maybe out of control yawing would give you a clue rudder movement is involved. Rudder pedals are not the same as rudder surfaces as you know.

Teldorserious

30th Sep 2013, 01:59

Reminds of Bonanza V tails coming off at Vne...but the speeds were so high as to create a flutter, oscilation. Ofcourse that was a mechanical problem, blamed on pilots going to to fast, but ofcourse everyone has the tail mod now, surprise surprise. So ofcourse, Beech wasn't to blame, but you haven't had a V tail come off since. Surprise surprise.

I think it was the Meridian that had the tail come off in turbulence, everyone said the A/P did a pitch over, exceeded Vne causing the tail to come off. They have an A/P check, reduced Va for turbulance and forced the pilots to go to school to fly this tricky plane and how to handle it. They did a tail mod too...surprise surprise.

So the Airbus tail comes off...did they buttress and mod the tail or didn't they? Why fix something that aint broken?

Rabbit by your own post you mentioned that your NTSB guys show you the real deal but offical findings are different, for reasons you can't fathom. It's called politics and economics.

AirRabbit

30th Sep 2013, 02:51

Rabbit by your own post you mentioned that your NTSB guys show you the real deal but offical findings are different, for reasons you can't fathom. It's called politics and economics.

That's not what I said. The official NTSB reports that I see are the same ones you see. I am acutely aware of the "politics" that happen in governmental agencies ... but the same kind of "issues" are every bit as prevalent in non-governmental organizations - from airlines to churches. Where ever there are policies and procedures, there's the makings of short-cuts, special deals, lack of publication isssues, and all the rest. The offical NTSB report is available to anyone who wants it. All the FDR traces, the CVR transcripts ... everything that is used by the board in its determinations go into their Official Report. It's been a while, but I imagine that the NTSB has a web site from which anyone is likely to be able to download a oopy of any report the board has published, including AA587. What I said was that I have seen information contained in the Official NTSB Report and when I read the text of the Boards findings - there are times that it seems that some of the contents of the report are not addressed in the findings. I've never been able to get anyone to explain how that may happen ... but I know that it does occur. Certainly you can get an understanding of a novel by reading the Cliff Notes version ... but its not the same as reading the book! IF you want to know what the NTSB had in their possession, what they had available to review to develop their determinations - I'd strongly suggest you get a copy of and read the official NTSB Accident/Incident Report.

Here is a link to the Summary of this accident. From this page you will be able to download a full copy of the report ... if you are interested.
Accident Investigations - NTSB - National Transportation Safety Board (http://www.ntsb.gov/investigations/summary/AAR0404.html)

Teldorserious

30th Sep 2013, 03:30

Air - Their report will say the pilots shouldn't use too much rudder...but what isn't in the report is that Airbus has quietly inspected, fixed, and stiffened up all the tails.

flarepilot

30th Sep 2013, 04:34

air rabbit

the transports I fly DO have placards for gear extension speeds and flap speeds. don't yours?

and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.

methinks you protect airbus too much.

and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400

all sorts of things happen in real life...we even had a special provision for the flight attendants to NOT wear high heal shoes as they were damaging the floorboards in the cabin.

wake up to reality

a plane crashed, pilot blamed

but enough other pilots have spoken up on this forum and in other places to make everyone wonder.

SHEESH

Brian Abraham

30th Sep 2013, 06:19

Guys, guys, Teldiserous is the latest incarnation of SSG and has never sat behind the controls of ANY aircraft. A flight simmer at best, and has proven time after time to have little to no understanding of aircraft ops.

I'm no troll as he claims, if anyone should have doubts I'll happily put those doubts to rest.

Teldorserious

30th Sep 2013, 07:36

Please contain your comments to things pertinent to the thread's subject matter. Brian's comments may irritate you but they don't get to the point of being offensive. Certainly, you have a right of reply but not open slather to be offensive.

Volume

30th Sep 2013, 07:42

How about a hypothetical conversation with an Airbus test pilot -
'How did you determine Va'Oh we did not do that. Our Engineers did. And they used the very same and old formula you find in Books for 100 Years...
Va = Vs * sqrt(n).
No Rocket Science, not brand related.

Chris Scott

30th Sep 2013, 10:47

Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident in which one or more of the main contributors, usually of dubious credentials and having lost the logical part of the argument, didn't resort to the usual accusations of corruption and collusion on the part of the manufacturer/regulator/investigator? I'm not holding my breath. :ugh:

For those who haven't flown big jets yet, and who may be impressed by all the derring-do being pedalled by some contributors here, here's my humble line-pilot experience - for what it's worth.

In the period (1971 - 2001) that I flew six different types of swept-wing big jets for a living on boring, public-transport operations, I never used the rudder except to:
(1) keep the a/c straight on T/O (backed up, if necessary, with into-wind aileron but without "cracking" the roll spoilers);
(2) to help induce a mild sideslip just before the flare when using the wing-down crosswind-landing technique (not on the B707!);
(3) to decrab, as necessary, on a crosswind landing;
(4) to keep the a/c straight during the landing run;
(5) to counter asymmetric thrust following an engine failure.

Note that only (1) and (4) involved rapid reversal of input, and only on the ground at low airspeeds. There were one or two colleagues who would use a bit of rudder to increase the rate of entry into a turn (usually when they were trying to captutre the ILS localiser), but this was frowned upon because it involved sideslip. Except in (2), and a little bit in (5), you do not induce sideslip on a big jet, partly because it is uncomfortable for the passengers and cabin crew. But in any case, it is simply bad flying. We do not need full rudder to pick up a wing in a stall because:
(a) IIRC, certification demands that aileron is usable (and recommended) in the recovery from a simple stall;
(b) we do not stall the aeroplane in public transport ops. However, in the extreme case, a stall normally occurs at a low airspeed.

Can I repeat another point I tried to make in a previous post? The A300-600 flight controls and tail-assembly structure are similar to the A310 I flew in the 1980s, although the VS dimensions may be slightly different.
Despite what flarepath would lead us to believe, there is a rudder travel limiter which becomes effective above a certain IAS (a bit above minimum-clean speed, IIRC). That limiter is a fuction of two computers called FACs. If it fails, the ECAM system (which was pioneered on the A310), announces something like "F/CTL: Rudder travel Limit INOP. Use rudder with care above xxx kt." This is accompanied by a master-caution W/L and a SC (single chime). Very similar to the A320 and its successors.

What the above-mentioned contributors are also in denial about is that, despite being reminded by tdracer and others, Boeing has quite clearly recognised the need to warn pilots not to cycle the rudder from stop to stop on its own airplanes. But who ever did?

Owain, I'm wondering if the B52 may have ailerons and elevators that use balance panels like the B707? In which case loss of hydraulics with the rudder, which may have an hydraulic booster like the B707, would not affect them. The main point about that a/c was that, as Armchairflyer says and you would know far better than I do, there was enough of the fin left to provide some degree of directional stability (unlike that B747 in Japan, caused by a botched repair to the rear pressure bulkhead).

Owain Glyndwr

30th Sep 2013, 11:45

Chris,

I really don't know much about the details of B52 design. I am going from this extract taken from the B52 history site:

An unusual feature of the B-52 was the use of a pneumatic system as the primary power source in the operation of all auxiliary functions aboard the aircraft. High pressure, high temperature air was bled from the second stage compressor of each jet engine, and carried by ducts to the desired locality in the aircraft where it was transformed into electrical or hydraulic energy by air turbine-driven power packs. There were ten turbine-driven hydraulic pumps which supplied pressure at 3000 pounds per square inch to drive the brakes, steering mechanism, spoilers, bomb bay doors, and the adjustable stabilizer. The pneumatic system also drove air turbine alternators which provided the electrical power for the aircraft. That suggests to me that they may have retained roll and pitch controls - I note that there is no mention of a power pack supplying hydraulics to the rudder, but as I said, I am looking for confirmation. This in contradistinction to the A300 which would definitely have been without any form of control.

As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.

Bottom line is that the B52 survived, so it must be possible in at least one case.

Clandestino

30th Sep 2013, 12:26

Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.
Whatever! That is what happened. NTSB investigation reference or it didn't.

what isn't in the report is that Airbus has quietly inspected, fixed, and stiffened up all the tails. Probable cause: no official requirement to include paranoid delusions into NTSB reports. Write to your congressman if you are unhappy about that.

Chris Scott

30th Sep 2013, 13:56

Quote from Owain Glyndwr:
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.

Point taken. Very different fuselage profile from the B747...

galaxy flyer

30th Sep 2013, 14:03

That was prior to the B52G models which did away with the bleed air feed services. A lot if leaks that sent hit air thru all kinds of places it didn't belong. That said, the "finless" BUFF was an early model.

DozyWannabe

30th Sep 2013, 14:04

...getting it right on the drawing board and making them Boeing tough?

It's not about brand B being tougher than brand A and never was. While the 747SP deserves kudos for hanging together in that China Airlines incident, you're talking about a completely different scenario causing completely different load factors on the airframe.

That incident involved a spiral dive - to cut a long description short, the torsional/bending loads are spread across the airframe and occur primarily to structures with spars, such as the wings and horizontal stab. The vertical stab will take some heavy punishment, but the loads only occur in one direction. Reversed sideslips of the kind that brought down AA587 apply almost all the torsion loads to the vertical stab - which is dangerous enough, but when you add in the reversals it quickly becomes more than any design of that size and that nature can handle.

As the photo earlier in the thread shows, not even the 747 has a spar or structural member going from the fuselage to the vertical stab. Like the A300 and pretty much every other aircraft of the type, the vertical stab is simply bolted on through lugs.

Brian - thanks for the clarification on the identity of our FUD merchant.

Airbus has quietly inspected, fixed, and stiffened up all the tails.

Utter rubbish. Inspected and fixed those that needed fixing yes, but there was no programme to "quietly" make changes to all of them because it simply wasn't necessary.

Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident...

@Chris Scott - Amen!

PJ2

30th Sep 2013, 15:49

Chris, regarding:
Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident in which one or more of the main contributors, usually of dubious credentials and having lost the logical part of the argument, didn't resort to the usual accusations of corruption and collusion on the part of the manufacturer/regulator/investigator? I'm not holding my breath.Reading some of the vitriol that passes for "discussion", one wonders what airlines spent all that time and money on CRM for and why, that is, if indeed those contributing are actually transport pilots.
I second your comments which are very well stated, (specifically, points 1 - 5, & a-b), regarding rudder use. Your comments characterize and reflect my own experience in handling transport aircraft.

AirRabbit

30th Sep 2013, 19:57

the transports I fly DO have placards for gear extension speeds and flap speeds. don't yours
and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.
methinks you protect airbus too much.
and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400
It’s a shame that you read incorrectly when you interpret my comments here as being a “fan” or a “protector” of Airbus. I’m not particularly “for” or “against,” that particular manufacturer, despite your acusations.

wake up to reality
a plane crashed, pilot blamed
but enough other pilots have spoken up on this forum and in other places to make everyone wonder.
SHEESH
I am quite sure you have not read many, if any, of my previous posts here, and have not had the opportunity to accurately interpret any of what I might offer here. So … let me assure you that I don’t like laying the blame for an accident at the feet of any pilot – unless that is the correct place. In fact, with regard to this specific accident, I seem to recall my previous posts (some 6-8 years ago, or more) saying that the F/O most assuredly was at the controls when this particular accident occurred. It was this F/O who made the control inputs that resulted in the tail separating from the airplane – it wasn’t because of poor workmanship or substandard materials or construction. BUT, after having said all that, I also said that this F/O most assuredly had lots of help in getting to the accident site. I also said that this particular flight encountered 2 wingtip vortices, not just 1. This F/O transitioned the first encounter quite professionally and with very little use of the rudder, if any at all. My question originally (and it remains a question in my mind today) had to do with why the precise, subdued, professional, and very successful transition with the 1st encounter … and the result of the 2nd vortex encounter being the overly severe control applications in all three axes, but most significantly in lateral and directional control responses – and the fact that those responses went to the control limit a good share of the time and consisted of substantially, and very quickly, reversing those inputs. Did he remember his training the 1st time (which was successful) and forget it the 2nd time (which was unsuccessful)? Or, did he forget his training the 1st time, and after recognizing that what he did was successful - i.e., the airplane maintained the desired flight path – then with the 2nd encounter, decided to do something way beyond what he had just witnessed and experienced as being successful and decided to maximize his control inputs? We may never know. But I think it appropriate for all of us to carefully analyze what happened, including what the results were with both of the "corrective actions" taken … and ensure that this information is widely disseminated and incorporated into all airline pilot training programs.

Did the AAMT course once offered by AA have anything to do with the magnitude of response used in this second encounter? I don’t know. And I don’t think anyone can say for sure. I know that the AAMT course did discuss the use of the rudder – but as I recall my exposure to that particular course (and no, I wasn’t employed by AA), was that the use of the rudder would be appropriate to assist in bringing the nose back to the horizon if using down-elevator was inappropriate or ineffectual after reaching an unacceptably high pitch attitude. Once achieving an angle of bank, pressuring the bottom rudder would bring the nose back to the desired attitude with respect to the horizon. I am also aware that AA did modify the content of this course to be sure that they weren’t encouraging an inordinate use of the rudder – and, I understand, eventually dropped the course altogether. However, if this course did contribute to the accident, it would leave open the question as to why the substantial use of rudder seen prior to the separation of the vertical tail did not occur during the first wingtip vortex encounter?

I hope this clarifies my comments for you.

john_tullamarine

30th Sep 2013, 20:51

Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident...

Sometimes we mod folks tear our hair out trying to tread that fine line between too much interference (stifling debate to the point of overt censorship) and seeing some folk get too excited (too far beyond the reasonable bounds of polite discussion).

The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.

DozyWannabe

30th Sep 2013, 20:58

@AirRabbit

I doff my cap to you for a thoughtful, well-reasoned and insightful post.

One thing I remember from the time was a BBC Horizon documentary that stated a significant number of that FO's colleagues on AA's A300 fleet had transferred to Boeing types because they believed whole-heartedly in the "weak tail" scenario. Such actions speak to camaraderie and loyalty and they are no doubt noble, even if the evidence points elsewhere.

But if we are to be rational about things then we must follow the evidence, even if we don't like where it may lead. Heaven knows I've been accused enough times of "defending" or "protecting" Airbus when sticking to the evidence is all I've been doing. At the end of the day, even with the speculation over why the FO may have handled the rudder the way he appeared to, there is no arguing with the fact that the vertical stab did not fail until the forces on it exceeded the load limit by a factor of 2.2 times, exceeding the Ultimate load reserve by a factor of 1.47 times.

bubbers44

30th Sep 2013, 21:12

I, along with a lot of other pilots on this thread, believe overiding an autopilot or autothrottle not doing what you want it to do is improper and should never be done on an Airbus because of Airbus policy.

I guess that is why I always flew Boeings because they were just an airplane and you could overide anything you chose to overide. I know I can correct a situation hand flying but Airbus says, NO, push this button. I think Airbus has made their pilots into flying robots. AF447 demonstrated this when all they needed was one pilot who knew how to hand fly but he was taking his break. Maybe he should have stayed in the cockpit to take care of the children of the magenta line. Pilots should always be pilots and not let the company make you into a computer operator.

AirRabbit

30th Sep 2013, 21:33

Sometimes we mod folks tear our hair out trying to tread that fine line between too much interference (stifling debate to the point of overt censorship) and seeing some folk get too excited (too far beyond the reasonable bounds of polite discussion).
The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.

Hey John – this forum, and by extension, YOU, do(es), and have done, what most here would describe as a magnificent job of reviewing the posts and allowing the development of what develops. It is a very, very rare circumstance to have what develops here, be even remotely described as an out-of-hand spool-up to name calling and disrespect. All of us here should be so fortunate or work so hard as to find ourselves/themselves an equally “fallible human.” You, sir, and this forum, deserve at least a handful of “atta-boys” for the kinds of information exchange you provide to all of us – and there’s probably no way to measure the value that has produced.

DozyWannabe

30th Sep 2013, 21:50

I, along with a lot of other pilots on this thread, believe overiding an autopilot or autothrottle not doing what you want it to do is improper and should never be done on an Airbus because of Airbus policy.

Bubs, are you sure you're replying to the right thread? If you're sure, then JammedStab followed his original post on "Manually overriding autothrust" stating he'd misunderstood the document.

Said document is here: http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS_SOP_SEQ02.pdf

and the relevant section is at the bottom of page 7.

If you read it in context, all it says is that a pilot should not try to override AP or A/THR by manipulating the controls without first explicitly using the disconnect button.

Note that it also says (emphasis mine):
If doubt exists regarding the aircraft flight path or
speed control, the flight crew should not try to reprogram the automated systems.

The flight crew should use Selected Guidance or hand flying together with the use of navaids raw data, until time and conditions permit a reprogramming of the AP/FD or FMS.

Yup, you read it right - an official Airbus document telling pilots to handfly. Now, if people paid attention to what Airbus *actually* say rather than assuming the ol' rumour mill must be correct, then that shouldn't be much of a surprise. Unfortunately...

PJ2

30th Sep 2013, 21:50

" You, sir, and this forum, deserve at least a handful of “atta-boys” for the kinds of information exchange you provide to all of us – and there’s probably no way to measure the value that has produced."

yessir, very well said, AR, +1

AirRabbit

30th Sep 2013, 21:51

I doff my cap to you for a thoughtful, well-reasoned and insightful post.

One thing I remember from the time was a BBC Horizon documentary that stated a significant number of that FO's colleagues on AA's A300 fleet had transferred to Boeing types because they believed whole-heartedly in the "weak tail" scenario. Such actions speak to camaraderie and loyalty and they are no doubt noble, even if the evidence points elsewhere.

But if we are to be rational about things then we must follow the evidence, even if we don't like where it may lead. Heaven knows I've been accused enough times of "defending" or "protecting" Airbus when sticking to the evidence is all I've been doing. At the end of the day, even with the speculation over why the FO may have handled the rudder the way he appeared to, there is no arguing with the fact that the vertical stab did not fail until the forces on it exceeded the load limit by a factor of 2.2 times, exceeding the Ultimate load reserve by a factor of 1.47 times.

You have, as I think I’ve said before (probably several times), both my respect and my admiration. So, thanks for your comments – and I look forward to reading what you have to say on almost anything, because I’ve long ago recognized that most of the participants here are really after the truth about whatever it is being discussed. It’s far easier to jump on the most popular bandwagon – and sometimes having done so … remain ignorant of the facts … or worse, maybe influence some reasonably inexperienced aviator out there who gloms onto something posted by a seasoned old fart and finds out that he or she has made a serious error in judgment. There is absolutely no reason to NOT learn the truth about anything discussed here – because the truth will not only set you free, it might also save your butt!!

Chris Scott

30th Sep 2013, 21:59

Quote:
Hey John – this forum, and by extension, YOU, do(es), and have done, what most here would describe as a magnificent job of reviewing the posts and allowing the development of what develops.
...You, sir, and this forum, deserve at least a handful of “atta-boys” for the kinds of information exchange you provide to all of us – and there’s probably no way to measure the value that has produced.

Hear, hear... Thanks for articulating those sentiments much better than I for one could have done, AirRabbit. Something as close to the truth as fallible humans can aspire to will out... eventually.

DozyWannabe

30th Sep 2013, 22:26

You, sir, and this forum, deserve at least a handful of “atta-boys” for the kinds of information exchange you provide to all of us...

Perfectly put.

And on a more personal note, I should thank the mods for being lenient to an enthusiast with scant qualifications, who as a result has learned more than he ever could hope to have done any other way. Not to mention making the acquaintance of several stellar pilots, engineers and people in the process.

john_tullamarine

30th Sep 2013, 23:35

Guys .. enough, already ... lest I get an undeserved swelled head.

However, this forum is too important for the folks who use it to let it swing too far either way .. better we maintain a reasonably polite but vigorous and spirited debating platform for whatever topics arise.

We all have the potential to learn from PPRuNe.

I have a small insight into the IDs of some of the posters. If you or I were to seek their advice on a commercial consultancy basis (and many of them are highly regarded Industry Consultants), we would be paying a small fortune for what we are getting here as freebies.

That never ceases to amaze me.

misd-agin

1st Oct 2013, 01:06

Air - Their report will say the pilots shouldn't use too much rudder...but what isn't in the report is that Airbus has quietly inspected, fixed, and stiffened up all the tails.

Really? Airbus stiffened all the tails? On just the A300's? Or the A300-600R's? Is there a difference between the two aircraft? Does it matter?

Or did Airbus stiffen every Airbus tail ever built?
When did they do this? What was the 'fix'?

Brian Abraham

1st Oct 2013, 04:36

Hear, hear for and to those who quite rightly have applauded JT. A gentleman much experienced aviation wise, and does the greatest of jobs riding herd on this community of cats. Helo guy myself, know nought of big iron, but through these august pages have had the privalege of correspondance with proffesionals who have worked and flown on aircraft mere mortals can only dream about. All spilling errors tablet induced.

HazelNuts39

1st Oct 2013, 10:33

The NTSB Accident Report on AA 587, paragraph 1.18.10 Airbus Technical Note, states:
On April 8, 2004, Airbus issued a technical note, titled “AAL 587 – Pedals Force Analysis,” that provided Airbus’ estimate of the rudder pedal forces during the seconds before the vertical stabilizer separated from the airplane. Airbus used FDR data for rudder pedal position, estimates of rudder position, estimates of yaw damper position, and ground test data to derive the pedal force estimate.
The technical note indicated that, during the accident sequence, the forces applied by the first officer to the rudder pedals were much higher than the forces required to reach the rudder travel limit for 240 knots. Airbus found that the highest force applied by the pilot during the accident sequence was about 140 pounds but that the pedal force required to reach the rudder travel limit during that time was about 30 pounds. The note further indicated that the rudder control cable was stretched each time that the rudder travel limit was contacted.The Airbus note is not discussed in the NTSB report that was published in october 2004, and I could not find it on the NTSB website. Has anyone more information?

roulishollandais

1st Oct 2013, 13:24

… remain ignorant of the facts …
Despite reading PPRuNe and our august posters, I am still ignorant of the exact text of FAA's Va old and new definitions:O Is it Defence secrecy? :p

@Clandestino
What we learned first, Critical situation
• Not sure you have taught new pilots. Did you ?
• We don't have the same definition of "critical [situation]" :mad:

Chris Scott

1st Oct 2013, 14:11

Quote from dutchroll:
Despite reading PPRuNe and our august posters, I am still ignorant of the exact text of FAA's Va old and new definitions.

You and me both!

Owain Glyndwr

1st Oct 2013, 14:34

@Chris, Roulis

I think you will find what you are looking for in posts #21 and 23 of the "Va Maneuvring" thread.

This involves subtle distinctions between "Maneuvring speed" and "Design Maneuvring speed". I suspect this was the origin of this thread, but Teldorserious hasn't confirmed that despite repeated requests.

HazelNuts39

1st Oct 2013, 15:14

Va is defined in FAR 25.335, last changed with Amdt. 25-91 Eff. 7/29/97. The change was made to harmonize FAR and JAR.

Owain Glyndwr

1st Oct 2013, 15:29

Va is defined in FAR 25.335, last changed with Amdt. 25-91 Eff. 7/29/97. The change was made to harmonize FAR and JAR.

Agreed HN, but that refers to the design manoeuvre speed. The FAA changes made following the NTSB AA587 recommendation related to FAR 25.1507 and 25.1583

AirRabbit

1st Oct 2013, 15:51

Quote:
Originally Posted by Air Rabbit #135
… remain ignorant of the facts …
Despite reading PPRuNe and our august posters, I am still ignorant of the exact text of FAA's Va old and new definitions Is it Defence secrecy?

Umm … forgive me, but I’m not sure if you’re asking a question or not … and if you are, I’m not sure what that question might be. If you are seeking to read the FAA’s current definition of Va, here is a reference for you to read: § 25.335 Design airspeeds.

DozyWannabe

1st Oct 2013, 15:53

When AA587 lost its fin it also lost all hydraulics since it was supplied by all three systems. Consequently there was no aerodynamic control of any sort available...

While you're absolutely correct in a technical sense, if I understand it correctly the sequence of events following vertical stab separation progressed so quickly that there wouldn't have been enough time for the hydraulic fluid to drain.

I'm pretty sure that because the aircraft was already in a sideslip, the resultant loss of opposing force from the rudder/stabiliser would have caused what amounted to an unrecoverable flat spin within a fraction of a second, would it not?

Owain Glyndwr

1st Oct 2013, 16:24

@AirRabbit

If you go back to the OP you will find it querying FAA changes to "Va" after the Airbus deal I take this to mean the changes FAA made to their regulations as a result of NTSB pointing out the confusion that existed between Va used as a design speed and Va used as a manoeuvre speed.

If you check out the posts I cited earlier you will find that the FAA made changes to the definition of the latter, not to Va used as a design speed. Consequently I think that referring RH and CS to the latest definition of manoeuvre design speed won't help them - hence my reference to an earlier PPRuNe discussion.

@ Dozy

Not so much time to drain the systems Dozy, just that if the pipes are open to the atmosphere the working pressure drops to zero, so the remaining control surfaces will flop all over the place under whatever aerodynamic hinge moments they might experience.

I don't think we know anything about the subsequent gyrations and I would certainly not like to attempt any prediction - they were nowhere near stall when if happened so I don't see why it should develop an almost instantaneous flat spin - in fact a aircraft that size will not do anything much in a fraction of a second.

HazelNuts39

1st Oct 2013, 16:26

Owain,

Thanks, I just couldn't find the thread you referred to.

DozyWannabe

1st Oct 2013, 16:45

I don't think we know anything about the subsequent gyrations and I would certainly not like to attempt any prediction - they were nowhere near stall when if happened so I don't see why it should develop an almost instantaneous flat spin - in fact a aircraft that size will not do anything much in a fraction of a second.

Fair enough - I was speculating on possible momentum build-up from those pendulum-like yaw movements, but admittedly I'm way out of my depth - so if you say it's unlikely then I'm with you! :}

AirRabbit

1st Oct 2013, 20:14

@AirRabbit

If you go back to the OP you will find it querying
Quote:
FAA changes to "Va"
Quote:
after the Airbus deal
I take this to mean the changes FAA made to their regulations as a result of NTSB pointing out the confusion that existed between Va used as a design speed and Va used as a manoeuvre speed.

If you check out the posts I cited earlier you will find that the FAA made changes to the definition of the latter, not to Va used as a design speed. Consequently I think that referring RH and CS to the latest definition of manoeuvre design speed won't help them - hence my reference to an earlier PPRuNe discussion.

Thanks … and I have gone back to the thread and the posts you referenced – and interestingly in my dim memory, I vaguely recall the discussions that took place in my circle of colleagues when all that occurred … and even with those discussions I don’t think that any of us had that proverbial “light bulb” experience – because even with deciphering each individual word – there were still some areas that, at least to most of us, seemed contradictory or at least argumentative.

However, after all that, even with whatever level of understanding any of us may have had (even full understanding) with respect to what the revised regulation would have required or allowed, there is still the issue of not only control reversals, but multiple reversals, most of which were to the control limits, that would throw out all of the attempts to understand any logic or generate any sympathy for any such lack of intelligent understanding of those re-written rules. I still come back to not understanding why that pilot chose such wholly different control applications for what was essentially the same encounter twice.

john_tullamarine

1st Oct 2013, 20:52

Re Regulations and, hence, in this case, what Va might have meant from time to time ...

FAA current and superseded regs can be tracked down from here (http://www.faa.gov/regulations_policies/faa_regulations/).

Always one has to keep in mind that the regs should not be read in isolation but in conjunction with relevant ACs (http://www.faa.gov/regulations_policies/advisory_circulars/).

Tracking down superseded ACs can be a bit of a pain, unfortunately.

roulishollandais

1st Oct 2013, 23:25

@john_tullamarine, Owain Glyndwr, AirRabbit, Hazelnuts39, OK465, others...
Thank you very much to all : a big step has been done . I have much to read now before continuing to try to compare two definitions of Va. Strange but useful thread starting with a not so easy question as it seems. THANKS AGAIN! :):):)

Edit : add Short extract :
Code of Federal Regulations

Sec. 25.335

Part 25 AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Subpart C--Structure Flight Maneuver and Gust Conditions

Sec. 25.335

Design airspeeds.

The selected design airspeeds are equivalent airspeeds (EAS). Estimated values of and must be conservative. (a) Design cruising speed, V C . For V C ,the following apply: (1) The minimum value of V C must be sufficiently greater than V B to provide for inadvertent speed increases likely to occur as a result of severe atmospheric turbulence. [(2) Except as provided in Sec. 25.335(d)(2), V C may not be less than V B + 1.32 U REF (with U REF as specified in Sec. 25.341(a)(5)(i)). However V C need not exceed the maximum speed in level flight at maximum continuous power for the corresponding altitude.] (3) At altitudes where V D is limited by Mach number, V C may be limited to a selected Mach number. (b) Design dive speed, V D . V D must be selected so that V C / M C is not greater than 0.8 V D / M D ,or so that the minimum speed margin between V C / M C and V D / M D is the greater of the following values: (1) From an initial condition of stabilized flight at V C / M C ,the airplane is upset,flown for 20 seconds along a flight path 7.5° below the initial path, and then pulled up at a load factor of 1.5g (0.5g acceleration increment). The speed increase occurring in this maneuver may be calculated if reliable or conservative aerodynamic data is issued. Power as specified in Sec. 25.174(b)(1)(iv) is assumed until the pullup is initiated, at which time power reduction and the use of pilot controlled drag devices may be assumed. [(2) The minimum speed margin must be enough to provide for atmospheric variations (such as horizontal gusts, and penetration of jet streams and cold fronts) and for instrument errors and airframe production variations. These factors may be considered on a probability basis. The margin at altitude where M C is limited by compressibility effects must not be less than 0.07M unless a lower margin is determined using a rational analysis that includes the effects of any automatic systems. In any case, the margin may not be reduced to less than 0.05M.] (c) Design maneuvering speed, V A . For V A ,the following apply:

(1) V A may not be less than where--(i) n is the limit positive maneuvering load factor at V C ; and (ii) is the stalling speed with flaps retracted. (2) V A and V S must be evaluated at the design weight and altitude under consideration. (3) V A need not be more than V C or the speed at which the positive C Nmax curve intersects the positive maneuver load factor line, whichever is less. (d) Design speed for maximum gust intensity, V B . (1)

Vb ≥Vs1 [ 1 + Kg. Uref. Vc. a / 498 w ] ^ ½

where--V S1 = the 1-g stalling speed based on C NAmax with the flaps retracted at the particular weight under consideration; V C = design cruise speed (knots equivalent airspeed); U REF = the reference gust velocity (feet per second equivalent airspeed) from Sec. 25.341(a)(5)(i); w = average wing loading (pounds per square foot) at the particular weight under consideration.

Kg = .88 Mu / 5.3 + Mu
Mu = 2w / r.c.a.g

r = density of air (slugs/ft ); c = mean geometric chord of the wing (feet); g = acceleration due to gravity (ft/sec ); a = slope of the airplane normal force coefficient curve, C NA per radian; (2) At altitudes where V C is limited by Mach number--(i) V B may be chosen to provide an optimum margin between low and high speed buffet boundaries; and (ii) V B need not be greater than V C . (e) Design flap speeds, V F .. For V F ,the following apply: (1) The design flap speed for each flap position (established in accordance with Sec. 25.697(a)) must be sufficiently greater than the operating speed recommended for the corresponding stage of flight (including balked landings) to allow for probable variations in control of airspeed and for transition from one flap position to another. (2) If an automatic flap positioning or load limiting device is used, the speeds and corresponding flap positions programmed or allowed by the device may be used. (3) V F may not be less than--(i) 1.6 ,with the flaps in takeoff position at maximum takeoff weight; (ii) 1.8 ,with the flaps in approach position at maximum landing weight; and (iii) 1.8 with the flaps in landing position at maximum landing weight. (f) Design drag device speeds, V DD . The selected design speed for each drag device must be sufficiently greater than the speed recommended for the operation of the device to allow for probable variations in speed control. For drag devices intended for use in high speed descents, V DD may not be less than V D . When an automatic drag device positioning or load limiting means is used, the speeds and corresponding drag device positions programmed or allowed by the automatic means must be used for design.

Amdt. 25-91, Eff. 7/29/97

Teldorserious

1st Oct 2013, 23:44

Well I am not buying it that airliners are so weak that some pilot or terrorist could intentionaly wiggle the tail loose. If that is the case, something is wrong with the hydros or the tail or the sensors or limiters that allow such actions.

Maybe the solution is to take the hydros out of it, make it all cranks and levers. If the pilot wants to put some rudder in, make him work for it, fight those aerodynamic forces, just like the rest of us in smaller planes that can't even imagine having enough legs to knock a tail off.

misd-agin

2nd Oct 2013, 00:00

Well I am not buying it that airliners are so weak that some pilot or terrorist could intentionaly wiggle the tail loose.

How about calling Boeing and Airbus and explaining YOUR theory to them? They disagree. Whip out your crayons and show them where they're wrong.

DozyWannabe

2nd Oct 2013, 00:04

If anyone else is hearing a faint buzzing noise, like an angry wasp banging against a window - I'd recommend ignoring it.

Teldorserious

2nd Oct 2013, 05:27

Misd - No one except a few peeps on PPRUNE believe that wiggling the tail will crash a plane, any more then three pilots over the Atlantic can't fly straight and level.

Owain Glyndwr

2nd Oct 2013, 06:54

misd-again

Whip out your crayons

Didn't you mean finger paints?

David Bass

2nd Oct 2013, 09:03

With respect to superseded ACs.

Online Digital Special Collections Library (http://specialcollection.dotlibrary.dot.gov/Sac_Notice.aspx)

This site appears to have many and is apparently not affected by the US government shutdown. It was not easy to find, however.

HazelNuts39

2nd Oct 2013, 09:28

Teldorserious,

Pedal forces of up to 140 lbs ... Just wiggling the tail, eh?

HazelNuts39

2nd Oct 2013, 12:41

Thanks JT for the link to historical aviation requirements.

On December 31, the requirement that specifies the design tail loads in the yaw maneuver (currently FAR 25.351, formerly CAR Part 04 (http://ntl1.specialcollection.net/scripts/ws.dll?websearch&site=dot_cars) section 4b.215) will celebrate its 60th birthday!

john_tullamarine

2nd Oct 2013, 12:46

.. and thank you to David Bass from us all for his gem.

flyboyike

2nd Oct 2013, 12:55

Oh, the love.

misd-agin

2nd Oct 2013, 14:37

No one except a few peeps on PPRuNe believe that wiggling the tail will crash a plane,

And Boeing, and Airbus, and the NTSB, and the FAA.

But in the internet world? Yup, it's a fraud. Good catch by you.

Now which a/c models did Airbus 'fix' the tails on? How? When?

Brian Abraham

2nd Oct 2013, 16:30

I'm just waiting for some one to realise that wiggling the stick to and fro above a certain speed makes the wings fall off. Wonder what his solution may be?

AirRabbit

2nd Oct 2013, 16:35

Just a thought...

Maybe what we should do is ask Teldor(no-one-really-believes-she-is)serious to take a Cessna 152 out for a trip around the traffic pattern and, on the downwind leg, do what was done on the 2nd vortex encounter on AA587. Is there anyone here who believes she will do it?

DozyWannabe

2nd Oct 2013, 16:56

AirRabbit

2nd Oct 2013, 17:18

I don't think even that's necessary. One way to think about it is that following Delta191 at DFW, the NTSB commissioned a study that involved deliberately driving a 737 through microbursts in order to collect data - a risky prospect. After Roselawn, they flew an ATR-72 behind a tanker spraying chilled water over the wings to study the ice ridge build-up behind the de-icing boots - an incredibly risky prospect.

And yet they never even entertained the idea of going up in an A300 or B767 and repeating the rudder pedal movements they saw on the AA587 FDR. That should speak volumes to a dispassionate observer.

Actually, I heard that they actually did discuss doing just that, but when the proposal was made in front of an audience of all the Airbus and Boeing test pilots, all five of the pilots who volunteered (all the rest scrambled out of the auditorium quickly) agreed only to man the ground based photo record cameras.

AirRabbit

2nd Oct 2013, 19:11

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. The aerodynamic loads placed on the vertical stabilizer due to the 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 (http://www.ntsb.gov). The full report will appear on the website in about four weeks.

NTSB Office of Public Affairs: (202) 314-6100

flarepilot

2nd Oct 2013, 19:17

Lord Spandex Masher

2nd Oct 2013, 19:23

Yeeeeeeeeeeeeeeeeeah! Clutching. At. Straws. Sevenstrokeroll. Flown the A300 much have you?

AirRabbit

2nd Oct 2013, 20:15

the NTSB is full of humans...humans make mistakes...we have our opinions based on years of whatever we have been doing

my opinion is the airbus 300 series is a piece of shirt

remember that the FAA certified the A300

it also certified the training program used by American Airlines

it also certified the copilot

if they made a mistake somewhere, they could have made a mistake anywhere.

some engineering types are so concerned with elegance in engineering that they forget real life

(I am sure glad for long layovers … it allows me to read and think)

So, Mr flarepilot, I understand you acknowledge that humans sometimes make mistakes, and since the NTSB consists of human investigators and researchers, it is your opinion that the NTSB made a series of human mistakes in their conclusions in this instance. Right? Is it possible that the NTSB members have opinions based on their years of doing what they do, or not? You seem to be quite critical of their “final report.” It is clear that the NTSB recognizes that the FAA certified the A300, and that the FAA certified the copilot, and that the FAA certified the AA training program … were those mistakes as well? Was it a mistake made by the NTSB that they made those recognitions … or did the NTSB make a mistake by not recognizing the FAA made those mistakes in certification? Is that a double negative? This is sure hard to figure out ... isn't it? Humans making decisions, when they know they're fallable - other humans not recognizing that fallability when it occurs and reulting in mistaking additional errors as having been good decisions, and then they, themselves, make mistakes in using those positions to answer questions they have about other actions which they observed. Of course, they may have misinterpreted what they thought that they had observed, when what really happened is known only to those who actually completed the actions based on what they knew (or only thought?) was the correct decision to make based on what they knew about the surrounding circumstances - presuming of course, what they saw was actually what they perceived has happened and are not misjudging what they think they saw. OK, I think I've got it now. :ugh:

So, what organization certified you? You are certificated, aren’t you? Was it the FAA? Did whomever it was who certified you, make the same kind of mistake? Who determines when something is true or a mistake … you? If not you, who is it? The FAA? The NTSB? Some news anchor on TV? Do we all operate in our own little world – carefully protecting ourselves from all the “other” humans who are out there making mistake after mistake – do we all have to look out for ourselves – at all times – in all things? Can we trust anyone? About anything? Forget the evidence … accept only opinions based on years of doing something … right? Of course, no one has ever known of anyone ever doing anything wrong for a long period of time … right? Sure, that’s it. :ugh:

Well, thanks … I’m sure that there are a lot of us here who are as firmly entrenched in opinions as opposed to facts as you are – and I guess we just have to acknowledge that everyone has his/her own opinion … just like they have various body parts. Enjoy! :rolleyes:

flarepilot

2nd Oct 2013, 20:55

dear mr bunny boy...or aka air rabbit

yes the FAA certificated me...many times

evidence...how many times in modern history has additional evidence come to light years later?

call back in 20 years or so. and you fly the A300 all you want...I'll fly something else...made in the USA most likely.

and all the cute emoticons just add to your heft with all your book learnin'

but planes aren't supposed to fall apart and if they do, you have to warn the pilot ...but no warning...hmmmmm

and if there was a warning in some obscure engineering text...great, but someone forgot to tell the pilot.

I"ve flown with engineering types who had commercial or atp lic. get em talking and they would fly right into the side of a mountain or stall the plane...I've seen it.

Teldorserious

2nd Oct 2013, 21:57

Let's take the NTSB report, word for word, and cull for what is being said. Word for word. I just cut and pasted...

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 (http://www.ntsb.gov/). The full report will appear on the website in about four weeks.

Pugilistic Animus

2nd Oct 2013, 22:08

I don't think that the A300 is a bad airplane... one DHL survived a SAM attack and was controllable enough to fly on engine power as a sole means of control...to me that says something about that plane...the flight controls aren't designed to take the stress of rapid large flight control oscillations. In the case of the VS the torque moment is tremendous well above certification...

As an aside Vp which is Va based upon stall is Vs*(nlimit)^0.5 but since stall speed increases with weight the actual maneuver speed is not a constant
An accelerated stall above Vp would impart a force that is above the limit load

Nick Thomas

2nd Oct 2013, 23:09

"the NTSB is full of humans...humans make mistakes...we have our opinions based on years of whatever we have been doing"

Yes Flarepilot, humans do make mistakes so it's just possible that the FO made a mistake.

NTSB I presume consists of more than one person so a "human mistake" is more likely to be picked up by them than a human mistake would be picked up in the dynamic cockpit of an airliner.

"I"ve flown with engineering types who had commercial or atp lic. get em talking and they would fly right into the side of a mountain or stall the plane...I've seen it."

Flarepilot: Your comment above is interesting and I wonder if you could clarify the following:

1. When you were flying with "engineering types" how did you survive flying into a mountain?

2. If you observed a plane flying into a mountain, how did you know that the pilot flying was an"engineering type"?

3. If you are unable to answer 1 or 2 above, might it not be better to delete "I've seen it" and replace it with something along the lines of "That is what I suspect would happen"

As a simple soul am trying to understand your reasoning and sadly failing to do so. Therefore am hoping that your reply to the above three points will for me clarify your position.

bubbers44

2nd Oct 2013, 23:12

I had an FO when flying the B727 that over controlled every landing with PIO's.

I flew with him years later in the B757 and he was the ace of the base. He was smooth and way ahead of the airplane. I still think the captain who complained about his rudder usage got too much input to the NTSB. Everyone goes through a learning process going to a new airplane. I know, I didn't fly the A300 because I didn't trust it like a Boeing. Had no problems because they are so straight forward to fly. The extra pay wasn't worth it for me.

flarepilot

2nd Oct 2013, 23:26

forgive me nick thomas I was speaking in pilot slang...I realize that we are separated by a common language but I am assuming (possibly incorrectly) that my fellow pilots are the ones reading this forum.

I watched engineers who were so interested in talking about the engineering of the plane (while they were pilot handling) that they lost track of their airspeed and approached the stall (aerodynamic stall that is) and I had to remind them TO KEEP THEIR SPEED UP; (up , meaning in a safe range)>

And while they were under the hood (simulating instrument flight) they were speaking of engineering so much that they LOST SITUATIONAL AWARENESS and turned the wrong way on the BACK COURSE OF A LOCALIZER and were proceeding in the direction of a LARGE FRICKING MOUNTAIN RANGE...I again spoke up correcting their error.

I do hope this clarifies...we don't speak as if we are talking to the Queen...we speak like we are talking to fellow PILOTS.

NO, they weren't allowed to hit the mountain or stall the plane...I stopped them. Again, speaking in a manner that a pilot who has flown for many years might speak to a fellow pilot of similar background.

May I translate anything else for you?

And yes, maybe the first officer did crash the plane...but it is my opinion the plane failed the crew, the crew didn't fail the plane.

JammedStab

2nd Oct 2013, 23:41

It is odd how so many people live in denial of reality.

One poster refuses to believe that a vertical stabilizer can be broken off an airplane despite engineering evidence that this is exactly what can happen and why we now have warning not to make certain inputs on certain aircraft.

Others refuse to believe that a pilot made repetitive inputs on his rudder pedals despite direct evidence of it having been done as recorded on an FDR. Excuses such as yaw damper are thrown about despite that being impossible.

All of which reminds me of the Egyptair investigation and more recently the Ethiopian crash in Beirut. Fortunately for us in the west, we have a much smaller percentage of believers in theories that fly in the face of the obvious.

There may be other factors to consider such as how light a force is required on the pedals to get full deflection but that doesn't change the other evidence.

Pugilistic Animus

2nd Oct 2013, 23:51

FlarePilot

pilot how did the plane fail them when the were doing a maneuver outside of certification? I think their training in wake encounter recovery failed them i feel bad for the flight crew and I don't really blame them as the copilot was simply doing what he was taught ...

Nick Thomas

2nd Oct 2013, 23:52

Flarepilot

Thank you for your prompt reply.

I understand why you assume you are speaking to pilots.

I am of course not a commercial pilot yet I have a keen interest in aviation as I have in many other fields.

As an Architect I am interested in the design and construction of aeroplanes. In keeping up with aviation design I have learnt many things that are useful in my practise of Architecture.

I have found that keeping an open mind and not judging things on face value has also been helpful in my Architectural development.

flarepilot

2nd Oct 2013, 23:58

animus...if the pilot knew the plane would fall apart if he did, "X" then he would not have done, "X".

But the authority that certified the plane, pilots, airline and training didn't bother to make sure the pilot knew that "X" would cause the plane to fail.

so I don't blame the pilot...at worst I blame the system equally along the way...

NICK THOMAS...an architect...that's great. You might really enjoy reading, "Sliderule" by Nevil Shute (norway).

As a matter of fact, you might gain keen insight into my views about airplane structure by reading, or viewing the movie version of, "NO HIGHWAY" (sometimes known as "NO HIGHWAY IN THE SKY). Hope you do both.

You might even recognize the keen defense of the pilot in this book and how it does turn out to be the FREAKING AIRPLANE and not the pilot.

Do read them both and get back to me.

Pugilistic Animus

3rd Oct 2013, 00:35

Flarepilot I believe that general ignorance of operating strength limitations is very widespread...this is something that should be covered in primary training...obviously the FO didn't understand that because he was not taught. In fact my belief is that there was a systemic failure...more emphasis needs to be placed on operating strength limitations in general, there are lots of pilots who don't understand the limitations simply because they were never taught...the fact that the FAA approved such a syllabus is appalling and therefore I agree that the FAA should shoulder some of the blame. When Bob Hoover reverses his side slips back and forth he's going very slow he doesn't break the plane because he understands the limits

john_tullamarine

3rd Oct 2013, 00:51

galaxy flyer

3rd Oct 2013, 01:10

In my "line" experience, there is a common belief that the standards have fairly wide margins and using some of that margin is OK. Without certification or performance engineering experience, many don't comprehend how limited those margins are and how easily one can go from inside the envelope to way outside of it.

bubbers44

3rd Oct 2013, 01:15

If our A300 going out of control with yaw damper movements at 140 knots into MIA had happened at 250 knots would the VS had departed? Probably. I still stand with the FO that he didn't cause it no matter what NTSB came up with.

flarepilot

3rd Oct 2013, 01:20

pugilist animus

if you believe what you wrote, what is the problem of putting a placcard in front of the pilot saying: don't wiggle the rudder back and forth too much or the plane will fall apart...or any language you like to express this?

I have placcards right now telling me gear speeds, flap speeds and not to do a CAT II Ils if the equipment isn't working.

of course a placard that says the plane will fall apart will likely be bad for public relations

Pugilistic Animus

3rd Oct 2013, 01:28

One would have to placard all airplanes...it's better that the placard be in the pilots mind just as stall recovery should be.

flarepilot

3rd Oct 2013, 01:37

pugilist

then how about control limiters to make sure pilots don't over control?

and a placard is pretty cheap insurance until all pilots have been trained.

Pugilistic Animus

3rd Oct 2013, 01:58

Flare even with rudder ratio limiting the certification standards do not cover large control reversals... placarding would simply be a bandaide on a gunshot wound...why not placard stall recovery also? Only education can militate against a repeat of AA 587

flarepilot

3rd Oct 2013, 02:10

or better built planes puglist

and if you want a placard for stall recovery, I'm sure Air France will lead the way in placing the placard on their airbus fleet.

and I'll take a band aid any day...its better than an open wound.

by the way puglist

one plane I flew says don't move control wheel more than half way above FL400

now certainly I know that, but there is a placard...

oh maybe there should be one of those on the A300 too

Pugilistic Animus

3rd Oct 2013, 02:33

I suppose for now that PPRuNe serves as a placard, I hope :)
As far as "better planes" go, the weight of reinforcing the VS to survive such abuse would be prohibitive

HazelNuts39

3rd Oct 2013, 07:49

As illustrated in tdracer's post #100, and testified in the FAA's Final Rule on the matter, the 'placard' is now in the Airplane Flight Manuals of all transport category airplanes flying in the US.
The private citizen noted the proposed amendment is not retroactive, so it would not fix the problem for existing aircraft.
Although the proposed amendment would not be retroactive, the FAA has worked with airplane manufacturers to amend their AFMs for all major transport category airplanes used in U.S. operations. The wording now in the limitations section of these AFMs meets the requirements of this final rule.

HazelNuts39

3rd Oct 2013, 11:10

An accelerated stall above Vp would impart a force that is above the limit loadIs that true? As a layman I would think that although the load factor at Va may exceed nlimit, the load would not exceed limit load. But then I don't know much about structures.

Clandestino

3rd Oct 2013, 11:59

If our A300 going out of control with yaw damper movements at 140 knots into MIA had happened at 250 knots would the VS had departed?

Is this what you are referring to?

The flight was assigned an airspeed of 230 knots and cleared to descend from FL240 to 16,000 feet in preparation for landing at Miami. The FDR indicated that while the autopilot was engaged in the descent, the power levers moved from the mechanical autothrottle limit of 44 degrees to the manual limit of 37 degrees. As the aircraft leveled at 16,000 feet the airspeed decreased. The F/O began a right turn to enter a holding pattern and added some power, which stabilized the airspeed at 178 knots. However, the right bank and the resultant angle of attack (AOA) continued to increase, despite left aileron input by the autopilot. As the autopilot reached the maximum input of 20 degrees, bank angle increased past 50 degrees, and the AOA increased rapidly from 7 degrees to 12 degrees. At this point the stick shaker activated, the autopilot independently disconnected, the power was increased, and full left rudder was used to arrest the roll. The bank angle reached 56 degrees, and the AOA reached 13.7 degrees at 177 knots. The aircraft then pitched down, and entered a series of pitch, yaw, and roll maneuvers as the flight controls went through a period of oscillations for about 34 seconds. The maneuvers finally dampened and the crew recovered at approximately 13,000 feet. One passenger was seriously injured and one flight attendant received minor injuries during the upset.
An analysis showed that the forces during the upset not only had gone above the design limit of the vertical stabilizer, they also apparently had reached the ultimate limit. In June 1997, Airbus requested that American Airlines perform another inspection of the jet to ensure it was not damaged. American inspectors, following Airbus' instructions, examined the tail fin. But they did not use methods that would have allowed them to see inside the tail fin. They saw no damage from their visual inspection, and the jet continued to fly until an ultrasound inspection of the horizontal stabilizer was done in March 2002. The inspection found two crescent-shaped cracks at one of the points where the tail fin attaches to the fuselage. The fin was replaced.

PROBABLE CAUSE:"The flightcrew's failure to maintain adequate airspeed during leveloff which led to an inadvertent stall, and their subsequent failure to use proper stall recovery techniques. A factor contributing to the accident was the flightcrew's failure to properly use the autothrottle."

Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.Is 1997. recent or there was another incident recently that no one around seems to know about?

bubbers44

3rd Oct 2013, 13:18

I remember that one too but this one about 20 years ago was on final approach to MIA requiring a go around because of uncommanded rudder movements that they could not stop. I would guess the NTSB would have blamed the pilots if they had crashed as they both thought was going to happen. I will try to find the report and post it.

bubbers44

3rd Oct 2013, 13:30

An airbus 300 on final approach at 1000 ft experienced uncommanded rudder inputs and rudder pedals v... - NASA ASRS (http://www.37000feet.com/report/436935/airbus-300-on-final-approach-at-1000-ft-experienced-uncommanded-rudder)

Owain Glyndwr

3rd Oct 2013, 13:40

HN39

As a layman I would think that although the load factor at Va may exceed nlimit, the load would not exceed limit load. The limit load (assuming the aircraft is designed by manoeuvre loads not by gust loads) would be 2.5g at MTOW and fwd CG limit. Strictly speaking that should be at MTOW less whatever fuel you burn to get there, but WTH! At Va you can just pull 2.5g at whatever weight has been used to define Va.

So if you are at a weight close to MTOW and at a speed above Va for that weight then you could in principle exceed both the 2.5g limit and the limit load. But at those conditions it is unlikely that one could pull enough 'g' to get anywhere near ultimate load (3.75g @ MTOW) if only because to get to a weight/airspeed condition where one could pull 3.75g one would have to burn off enough fuel to reduce the weight well below MTOW.

Owain Glyndwr

3rd Oct 2013, 13:47

bubbers44

Thank you for posting that report, but since it says several times that re-engaging the yaw dampers made things slightly easier, and since the problem was diagnosed as a failed autopilot yaw actuator clutch I don't see how your position re yaw damper failure as a possible cause of AA587 rudder movements can be sustained. Comment?

SMOC

3rd Oct 2013, 14:52

If the FCC detects a disagreement between the autopilot clutch and the autopilot selection, the FCC will command the respective main valve solenoid to close, thus depressurizing that channel of the autopilot actuator.

The examinations revealed two main findings: (1) the wiring to the two main valve solenoids had been cross-connected, and (2) a foreign-particle contaminant was found in the green system engagement valve solenoid.

Examination of the actuator at the Lucas facility revealed that its two main valve solenoids were cross-connected so that the electrical connection for the yellow system was connected to the green system solenoid, and vice versa. In this configuration, the FCC for the green system would actually control the main valve for the yellow system, and the FCC for the yellow system would control the main valve for the green system.

After the cross-connected wiring on N7082A was discovered, Airbus issued an All Operators Telex (AOT) on May 27, 1999, to all operators of Airbus A300, A310, and A300-600 airplanes. The AOT specified that a one-time inspection be conducted within 10 days to confirm proper connection of the main valve solenoids.

As a result of the AOT checks, another American A300-600 (N3075A) autopilot yaw actuator (S/N 1630) was discovered with cross-connected autopilot solenoid wiring. American indicated that it had installed new solenoids on the three actuators (pitch, roll, and yaw) on this airplane and the rest of its A300 fleet between July 1997 and July 1999. At the time the new solenoids were installed, procedures did not specifically include a check to ensure that the solenoid wiring was installed properly. Both Airbus and Lucas have since developed new procedures to ensure that the autopilot actuator solenoids are properly wired.

Lucas Aerospace, which is now known as TRW Aeronautical Systems obviously builds parts for Boeing and others as well.

And as stated above nothing to do with yaw dampers.

HazelNuts39

3rd Oct 2013, 16:05

Thanks Owain,

I probably misunderstood PA's remark.

bubbers44

3rd Oct 2013, 16:16

As I said I was using the info the FO gave me after the incident. I didn't read this report until a couple of hours ago. I agree they found rudder actuator clutch problems. I am curious how that would cause uncommanded rudder deflections. Seems like the rudder would either work or not work.

AirRabbit

3rd Oct 2013, 20:16

by the way puglist

one plane I flew says don't move control wheel more than half way above FL400

now certainly I know that, but there is a placard...

I wonder, with the placard reading “don’t move the control wheel more than half-way above FL400” … I would presume that you would feel perfectly comfortable in moving the control wheel to ½ of it’s maximum throw (I would presume that would be somewhere in the neighborhood of 67 degrees either side of neutral, right?) even if you were operating at FL410. Since you’re comfortable in moving the control wheel this way, how about moving it to 67 degrees left, and then immediately moving it to 67 degrees right, and then back to 67 degrees left, and then back to 67 degrees right, and keep that up for some 6 to 8 repetitions. Please note, the control wheel would not be moved more than half-way, so there would be no problem … right?

And, since there is apparently no placcard saying anything about a similar use of the rudder - would you consder doing the same control deflections - this time to the "stop" (physical or rudder limiter) for that same 6 or 7 repetitions. No placcard ... so ... no problem? Maybe, taking a clue from the lateral control placard, you might consider limiting your rudder inputs and reversals to only the same ½ value?

AirRabbit

3rd Oct 2013, 20:45

It is well understood by the engineering pilots around that there is a great problem with pilot education when it comes to what the certification animal does as contrasted with the line flight standards animal.

Fact of life and it is going to be a long while, if ever, before the typical pilot's knowledge base is lifted to the point where he/she has a basic idea of certification stuff.

.. which is why this Forum is so important. We have a bunch of very well credentialled

(a) line, training, check pilots

(b) TPs and FTEs

(c) certification, design, test engineers, aerodynamicists etc

(d) many anciliary specialists in airports and a host of other disciplines

The problem is that, sometimes, it can be difficult to sort the wheat from the chaff when posters are anonymous but that's a small problem overall as the more experienced folks offer comments (not always as subtle as might be desirable) which provide clues ...

Well, said – and, of course, quite accurate. And, in that same vein, with perhaps more than a little naiveté on my part, it would be my hope that ALL the readers here would take everything posted here as a potential fact until researched or thought through - or determined to be a perspective from a preconceived and/or prejudicial position and not necessarily willing to have the facts or truth lead to the ultimately correct conclusion. As for me personally, I choose to remain anonymous. The only reason for this decision, as I’ve said previously, is that I don’t think my employer would be appreciative of my “sounding off” (as you know I do) in such a public forum. I have a reputation with my employer for doing the same thing on the job and I pay for it regularly … but what I say is almost always retained within the organization in which I toil, and at least I still have my job - and I hope to keep it. However, if I were the janitor at the local Trailways Station – I can suspect what my “believability” might be … and, conversely, if I were the Senior Advisor to the FAA Administrator or the NTSB Deputy Chairman, whatever I say might (just might) enjoy some undeserved acceptance with little or no scrutiny. So, I prefer to offer what I offer in the hopes that I’ve made my points clearly and honestly enough to not depend on such “positional authority” to have anyone who reads what I say understand the accuracy of my comments.

bubbers44

3rd Oct 2013, 20:51

Unless you are doing 8pt hesitation rolls rarely do you need much more than 20 percent control movement in any aircraft.

AirRabbit

3rd Oct 2013, 22:00

…how did the plane fail them when they were doing a maneuver outside of certification? I think their training in wake encounter recovery failed them i feel bad for the flight crew and I don't really blame them as the copilot was simply doing what he was taught ...

With all due respect, sincerely meant, I’m not at all sure that the Wake Turbulence training they received was insufficient or even wrong. Recall that the tail was twisted off the airplane due to the F/O’s indiscriminate use of rapid rudder and wheel control inputs to the stops and just as rapid reversals of both controllers on repeated occasions … BUT … that was the SECOND vortex encounter. The FIRST encounter was transitioned without incident – by the same F/O, doing exactly what he had been trained to do – essentially rely on the inherent stability of transport category airplanes, aided ever so slightly by very minor control wheel inputs to aid or hasten return to wings-level. In fact the rudder controls were barely moved and the rudder surface was barely displaced.

AirRabbit

3rd Oct 2013, 22:03

I guess we'll never know why this F/O did what he did the SECOND time he encountered a wing tip vortex on the SAME departure ... 5 or 6 seconds after the first encounter recovery ... but it certainly wasn't what he was trained to do.....

bubbers44

3rd Oct 2013, 22:16

I guess he forgot everything he did a few seconds before and since that worked so well decided to stomp on the rudders until the tail fell off on the second encounter. Then again did anybody check the rudder actuator clutch? If it happened once it could happen again. I wonder if it was the same airplane?

bubbers44

3rd Oct 2013, 22:25

The upset training we got we all knew was to use the rudder in low speed upsets on approach to maximize recovery not for 250 knot speeds. It had nothing to do with AA Airbus crash in my opinion.

AirRabbit

3rd Oct 2013, 22:48

Then again did anybody check the rudder actuator clutch? If it happened once it could happen again. I wonder if it was the same airplane?

On the surface that might look like an excellent question. But, I think the report indicates that when this particular error manifested itself on the approach into Miami (I think) the airplane was apparently found to have had maintenance cross-connecting the autopilot servos (wasn’t it) and they said that it was extremely difficult to move the rudder pedals. The rudder pedals on AA587 were apparently quite easily moved … as the F/O move them from stop to stop some 5 times in 7 seconds. That doesn’t sound like “very difficult to move.”

bubbers44

3rd Oct 2013, 23:37

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.

roulishollandais

4th Oct 2013, 00:50

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.

We have two very different situations :

- The flightAA587 wastooken in a heavyand quick wake turbulence and the first officer did that violent pedal sharing very quickly - probably the captain had feet on the ground and could not avoid his FO pedaling quickly enough. It is a non pilot induced big oscillation of the airflow where the A300-600 had a stable dynamic, followed by a pilot action near of shocks givingexcessive conventional aerodynamic forces.

- In the both cases with Yaw damper failure, the possibility of DUTCH ROLL is important. You avoided it on your B727. Your friend and his Captain had less chance and developped the dutch rolll which is a resonance between the airflow movement around the whole aicraft and action with roll and/or rudder of the pilot to stop that PIO -inadequatlybecausethedutch rollisnot taughtto pilotsnoredescribed in ATPL books, where the problem is described as non existing with the yaw damper . But dutch roll may start by other initial disturbation - pushing one pedal violently (..in a sim issafer ) - and the pilot feeds himself the resonance acting on the stick and pedals AT THE WRONGMOMENT ANDWITH INADEQUATE SPEEDS. A good aerobaticflightculture may avoid/correct that resonance without equation, but it may be solved, in flight, by equations too.

bubbers44

4th Oct 2013, 01:13

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.

tdracer

4th Oct 2013, 02:17

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:

AirRabbit

4th Oct 2013, 04:09

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.

SMOC

4th Oct 2013, 05:09

Crash of AA Flight 587 on November 12, 2001 - YouTube (http://youtu.be/WWeLJHaXd8M)

A Squared

4th Oct 2013, 05:31

Well I am not buying it that airliners are so weak that some pilot or terrorist could intentionaly wiggle the tail loose.

So, how do you explain this:

CAUTION

The sudden revered of rudder direction at high rudder deflections, due to improper rudder application or abrupt release, can result in overstressing the vertical fin. This condition could be brought about during recovery attempts from a flight condition induced by a lateral control malfunction.

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.

A Squared

4th Oct 2013, 06:38

So you think FDR rudder inputs are measured at the pedals, not at the rudders?

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.

I believe the airplane did it.

Even though that is contradicted by all the evidence.

I think the FDR actually measures the rudder movement, not pedal movement....

It measures and records *both*

Did anybody ever bother to compare them?

Yes, the NTSB did

Probably not.

Yes, the NTSB did

If I was in the NTSB I would.......

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?

Lord Spandex Masher

4th Oct 2013, 07:32

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?

Owain Glyndwr

4th Oct 2013, 08:00

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.

http://i1081.photobucket.com/albums/j351/OwainGlyndwr/scan0232_zps96b38553.jpg

Bearing in mind the qualifications described in that report (different sampling times, yaw damper influence etc.) by any reasonable judgement the rudder deflection followed the pedal inputs. No system malfunction here!

Owain Glyndwr

4th Oct 2013, 08:17

roulis

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.

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.

A Squared

4th Oct 2013, 09:40

Then again did anybody check the rudder actuator clutch?

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.

Pugilistic Animus

4th Oct 2013, 14:16

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

pipeliner

4th Oct 2013, 14:46

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

Hear! Hear!

galaxy flyer

4th Oct 2013, 14:51

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: :}

DozyWannabe

4th Oct 2013, 18:37

Something I'm finding very disturbing about this thread is the suggestion/implication that the NTSB and FAA are incompetent or corrupt.

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).

flyboyike

4th Oct 2013, 19:07

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

AirRabbit

4th Oct 2013, 20:22

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?

flyboyike

4th Oct 2013, 20:25

I meant of the people I've flown with.

tdracer

4th Oct 2013, 20:34

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:.

DozyWannabe

4th Oct 2013, 20:55

IIRC, it came to light many years later that if certain electrical systems were damaged and the ground crew shut the power down then the CVR would automatically erase the tape.

flarepilot

4th Oct 2013, 21:02

how off course are we now?

Famous Hoot Gibson maneuver...well boys the plane went through hell and they all came out alive. Good for the plane

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".

Has anyone posted the dissenting opinion of one of the NTSB members on the airbus thing?

Do consider one thing ...on the preceding page one of the posters says the FO did the correct thing on the first wake encounter...and did something different during the second...why would he?

Lots of graphs, reports and other things...but very little on the human side.

If you do something right the first time, why change? Did he panic? Did he have itchy feet?

Interviews with other pilots? Sorry, I've seen too many pilots say different things because it helps their own "six".

DozyWannabe

4th Oct 2013, 21:12

Has anyone posted the dissenting opinion of one of the NTSB members on the airbus thing?

I haven't heard of such a thing existing - can you find it?

HazelNuts39

4th Oct 2013, 21:21

the FO did the correct thing on the first wake encounter...and did something different during the second...why would he?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.

DozyWannabe

4th Oct 2013, 21:31

For the sake of argument

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.

misd-agin

4th Oct 2013, 22:09

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.

Why read the report? It's much easier to accuse the NTSB of incompetence if you don't read the report OR understand the subject matter. :ugh:

HazelNuts39

4th Oct 2013, 22:22

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.

DozyWannabe

4th Oct 2013, 22:52

I didn't omit them as an act of commission - feel free to add them!

HazelNuts39

4th Oct 2013, 23:01

Dozy,

rather than picking pieces out of the NTSB's reasoning, I'd prefer that thread participants read it for themselves.

DozyWannabe

4th Oct 2013, 23:07

rather than picking pieces out of the NTSB's reasoning, I'd prefer that thread participants read it for themselves.

Agreed, but for those that can't be bothered, surely it's worth laying the basics out?

For those that want to read the report in full:
http://www.ntsb.gov/doclib/reports/2004/AAR0404.pdf

AirRabbit

4th Oct 2013, 23:23

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.

From what I recall and, I think, is again verified by reviewing the NTSB-sponsored creation of the animation (and a big thanks to SMOC for finding and posting it) is that the 23° left bank that existed at the initiation of the 2nd wake encounter seems (to me at least) to remain essentially constant until the very rapid right control wheel and right rudder applications. I fully recognize that this is simply an animation of the FDR traces – and that the FDR information was (as I recall) produced after being “filtered” from the digital recording to be able to print it as an analog trace – and I would feel a lot more comfortable with a “discussion” of what could have happened to generate the observed control application, rather than have someone simply say that “the F/O sensed a roll acceleration to the left.”

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.

bubbers44

4th Oct 2013, 23:41

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.

Teldorserious

4th Oct 2013, 23:50

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 (http://www.ntsb.gov/). The full report will appear on the website in about four weeks.