airtren

In fairness, that statement is not 100% false - the inhibiting bellow a certain g is true.

It can be amended, see bellow:

THS auto-trim is conditional to the load factor as follows:

THS auto-trim is limited between 'actual setting' and 2 degrees ND, when the load factor is above 1.3g.

THS auto-trim is inhibited/frozen when the load factor is bellow 0.5g.

Note: I used values from the copy of FCOM I had access to - "load factors" numbers seem to vary depending on documents referred (mine has 1.3g, and 0.5g).

BEA Report shows that Normal Acceleration varied within 1.65g to 0.6g range.

airtren

Roulishollandais,

So far, I don't think there is an indication within the perspective available on this forum that there is any software problem/bug.

If you see such an indication, please be specific.

In general, software is written according to system architecture and system block, or component functions, calculations and parameters specifications.

If any mechanism failed in its expected behavior - like the Stall Warning - there is no indication so far that it was because of a software problem or bug.

It is known it was because of NCDs (non calculated data) - due to icing and extreme AoA, which have inhibited certain sensors.

DozyWannabe

@airtren - The point is that the high-g number to which Lyman/Bearfoil/Will Fraser referred to is false and he was misrepresenting Takata's post (which was a very cheeky move, seeing as takata has not contributed since the 5th thread and as such was not here to refute the claims that our prolific water-muddying poster was making).

It won't autotrim any further nose-up over 1.25g, but the only limit for no autotrim whatsoever is 0.5g. If what you say is correct, and the FDR values indicate 1.65g max and 0.6g min, then there was nothing stopping autotrim from commanding the THS *nose-down* at any point. The other implication from takata's post was that manual THS trim is not subject to those restrictions, and that even if 0.5g was achieved, the manual trim wheels could still have commanded nose-down at any point. Now I remember from the very early days of the investigation that the THS nose-up trim stopped at 13 degrees with a theoretical maximum of 14. Could the g-loading demand limitation have kicked in to prevent it from moving that last degree in the wrong direction?

Either way, it is becoming increasingly clear to me that our prolific friend is looking more like the kind of sciolist that the big red letters at the bottom of every page caution us all about with every post he makes, and I'm hoping the mods will do some digging of their own to confirm or refute that idea. I may not be a pilot, but at least I'm honest about my intentions.

airtren

Old Carthusian,

The reading of your post seems to indicate an implying that there was no problem with any of the cockpit instruments, and all the pilots had to do is just follow them.

That would not be aligned with the BEA Report which states very clearly all the information known up to this time about which left side and backup instrument indications were and which were NOT available or functioning correctly and for how long, based on FDR and CVR data.

As the right side instruments are not recorded on the FDR, the availability of information will be clearer if that data can be reconstructed from other sources.

Furthermore, you seem to imply that there was a training problem in flying using instruments.

The lapsus in their training seem to be less, or none about how to use the instruments. It was mostly about how to handle the airplane at high altitude in loss of speed indications conditions, and then in stall approach and stall conditions.

jcjeant

Hi,

Little more ...

jcjeant

HazelNuts39

Lyman

g 'demand'. g 'command'. g 'limit'. g 'inhibit'.

Pick an axis (of the three), and explain how you get 'muddy water'? Better still, consider the three dimensional expression of this LOC. I'll wait.

Consider that TRIM is not an excursion, it is DWELL. It is anti maneuver, not pro. Different? No, opposite.

airtren

Dozywannabe,

Did you read "the" post?

The possible alternative to your interpretation is that the poster simply didn't recall accurately the FCOM text, or Takata's posted data, and posted information as he best could remember, at the excitement of his momentous recollection and inspiration. .... It is an opinion, with a number of disclaimers, as clearly stated by the author ...

Misinterpretation of data, lapses in memory are not uncommon even on official corporate or inter-corporate industry wide, or international standardization body forae, or mailing lists, on which the membership is very strict, and the technical level and content is as high as it can be.

They are in abundance on this Forum, and nobody gets or should be kicked out or censored for that, IMO.

This is a public domain Forum for discussion, with Aviation focus, with an open membership that is a lot wider than the professional variety of the Aviation industry in itself, which is very wide as it is, so stricter technical guidelines for information than those specified by the rules of the Forum do not seem to fit.

So personally, I don't have one bit of worry that anyone could intentionally hijack this thread and drive it into the ditch by injecting certain information. At the rate of posting, at the number and technical level of contributing members, and with the open public availability of Airbus documents and BEA reports, that's out of question. And of course don't worry, with someone that posts under what I perceive an enthusiastic drive to find explanations, rather than a mischievous intention to cause damage.
Ignoring, if bothered, is in such a Forum case a choice, IMO a lot less polluting, or image harmful than personal attacks.

Hm.... I am warming up, it's probably enough of a personal opinion.... so, can we relax now? and enjoy the technical dialog on the Forum?

There were several posts several pages back on this thread, based on data from Airbus documentation and the BEA report, including some graphs, with a discussion on the effect of the Elevator ND deflection, depending on the THS NU, Neutral or ND position, which I think captured well the effects of the THS.

Old Carthusian

Airtren
You seem to be chasing after a barrel full of red herrings. There is no evidence to indicate that the right and left displays were showing different information (which is what you seem to be implying - apologies if I am wrong in attributing this meaning to your post). The aircrew following proper scan procedures including the artificial horizon would have been rapidly appraised of the situation. In fact there are implications that the PNF did have some clue but didn't take any action. The PF did not perform a proper scan which suggests psychological issues and training issues. If the crew had followed SOPs, CRM and the procedure for UAS this accident wouldn't have happened. This is a training and CRM issue nothing else. I take it you have flown at night using instruments? If so you will know exactly what I am talking about when I talk about instrument flying.

jcjeant

Hi,

They had an artificial horizon or a half artificial horizon
I ask again for be sure to understand how the PF was able to give commands to level wings (if the many lateral commands had this means .. of course) and not able to give enough nose down elevators commands .. viewing the artificial horizon display ......

PJ2

Old Carthusian;
Perhaps the human factors group which the BEA's Alain Bouillard has implemented and directed to investigate these questions will learn why this was so. I wonder if there was a "cockpit gradient" issue - two F/O's do not have the same nature of authority and decision-making that a Captain/FO crew do. The discussion, which I know has been had here, about who was in command "really", as well as actually, is only part of this notion. In fact I get the subtle sense that the gradient was from right to left - higher in the right seat even though he was the junior crew member.

IIRC, clear direction was not provided by the captain on which crew member was to command the airplane, vice who was just going to fly.

Making a firm decision in such circumstances can be problematic depending upon company policies, training and even personalities.

Some airlines do not utilize two First Officers in Long Haul operations and provide two separate crews - Captain and F/O, to relieve the first crew. Whether this will turn up as an issue or even a comment we cannot say depending upon other factors that the Human Factors Group will discover.

A33Zab

jcjeant:

The Stall Warning logic itself is not at fault here.
It's the 'reducing' AoA value to 0° when CAS <60Kts by the ADIRUs which stopped the warning.
(We know they have changed that, don't know if its a part of the optional BUSS mod or if it is a separate -mandatory- mod)

Anyway this will be a legal case, who's to blame?
and I think we already suspect who will be blamed (for operating outside specs) at the end.

Old Carthusian

PJ2

My thoughts are very much along the same lines as yours with added psychological factors. I don't feel that I have enough information to articulate these in full yet. I do suspect that the Human Factors group is possibly going to be the vital element in establishing the cause of the accident though.

My comments on SOPs, training and CRM are because I feel that what has so far emerged supports this line of thinking.

AlphaZuluRomeo

Hi A33Zab
Would you (if you may) elaborate on the changes which have been made?
- what was changed, what is the new "logic"?
- when did that change took place, and why (mandatory? issuer?)

Thanks

GarageYears

Personally I have now TOTALLY given up reading any of the "selective reading disorder" originated posts by Bear/Lyingman/whatever, however I DO BELIEVE he is not in this for the good of aviation at all, but for the aggrandizement of Bear/Lyingman/whatever... glory in the screen pixels seems to be the only intent. Which is entirely sad and distracting to the well intended who post here.

Some here will have forgotten how adamant Bear was that the V/S was "torn off" early in the accident sequence... on and on, page after page, recurring at painful regularity, despite many who provided meaningful analysis on how that was not at all likely... and it wasn't/didn't.

Here we are again, on some "evil autotrim campaign" - autotrim "locked", babble, blah, etc.

The simple fact is the traces show that ND commands (few though they were) continued to control the pitch attitude, the THS had NOT locked the aircraft NU, and the damn thing was commanded NU on average all the way into the Ocean. If you like, autotrim, through a time-lagged smoothing function, attempted to offload the elevator demand COMMANDED BY THE PF... nothing more, subject a few limits to prevent stupid things happening. There are momentary periods where the "g" limit was reached, but the MEAN 'g' load was nowhere near the limit and as such the THS system was (hello!) AVAILABLE. It didn't move the THS, because the pilot did not demand it so... he asked for NU and got it. End of story.

There is an undeniable problem with any forum member who attempts to hide his identify be attempting to create a new one. Unless psycho-Bear/Lyingman/whatever can rationally explain why he did this (other than as an attempt to hide) then I'd suggest that this tactic alone is grounds to have his rantings eliminated from grown-up discussion.

And no, I'm not the board moderator, so by all means mods delete this post if it is deemed out of line. I have learned to skip over any post originated by our Troll, but the responses to his posts are a little hard to avoid, since several folks answering the loon have mostly worthwhile contributions.

Having stuck with this thread for 2+ years now, I'll be damned if I am driven away now, but seriously Bear - get off this stupid campaign that the airplane DID IT. The airplane did what the PF asked. Why he asked is a valid question, how to avoid someone making that same sequence of requests of the aircraft is valid, but to continuously infer, jumping from one theory to another, that the aircraft did anything without the pilots input demand is plain misleading. People screw up - professionals and non alike, in this case the result had a very bad outcome. Get over it.

Lyman

Let's see, one wearing a costume derides another wearing a costume for having more than one.

Do you think you have some manner of "call-sign?" A sussable ID?

This is an anonymous forum. You are straightforward and righteous, you have worn only one disguise?

The THS is inhibited >1.25, <.5. I mentioned .75. My Bad. I try attribution, and am "sowing pollution"?

"TRIMMABLE" HORIZONTAL STABILISER. That is not a correct designation, in design, practice, and Training. In fact, it is opposite what is trained.

What is trained is to leave the wheel alone, Only in DIRECT LAW challenge the virginity of the wheel and assault her with your palm.

NOT TRIMMABLE.

'TRIMMABLE' is an adjective, and describes a state of "readiness" or "availability".

"Subject to COMMAND". So the computer "commands" it, automatically, in its design. The PILOT is discouraged from COMMANDING it.

Parse? Words have meanings, and read with patience can be found to be used inappropriately, and perhaps dangerously so.

It is a TRIMMING Horizontal Stabiliser. In this discrepancy, patiently seen, can be a wealth of discussion as to how this system (AB) works, by design, application, and culture.

TRIMMABLE.....Optional. TRIMMING......MANDATORY.

In the climb, the pilot commanded NOSE UP, and the THS did not move. The THS was responding ("not responding") per design, not part of PF's quiver, for the moment (his 'bad').

At STALL, the THS responded immediately, and to the maximum, NOSE UP.

By DESIGN. Responding to PF NOSE UP? Or to gain loading for the airframe when it was less than 1g? Both?

Later, it went 'Dormant' at NOSE UP all the way down.

Posit. The a/c was UPSET at the loss of a/p, and LOC happened soon after ~ . With LOSS OF CONTROL, a design that trims in elevator for its retention when maneuvering is the order of the day? Hmmm.....

The THS, as it moves, changes the flight characteristics of the airframe, it changes the ANGLE OF INCIDENCE of the aircraft, as well as its PITCH.

This is why ANGLE OF INCIDENCE is considered separate from AoA, for it is a critical component of AIRCRAFT ATTITUDE.

Until one separates these two concepts AOI, AOA, the manner of control cannot be explained.

The HS is a VARIABLE INCIDENCE TAILPLANE, and focusing on its elevator chasing is missing the point, in a deadly way. Is this trained? Or is the training, merely, "don't touch that", and on your way?

lomapaseo

Its a shame that a technical thread can deterioate so badly because we don't all communicate under the same politeness.

In most of the forums that I have been, multiple user IDs are verbotten unless specifically permitted by the management. The worst is when a multiple ID user has more than one active at any one time seemingly to support their own opinions.

Thus I avoid all technical back and forth arguments where I suspect that this is going on.

Lyman

Loma

For goodness' sake. Technical/Anonymous forum is an oxymoron.

If you want white papers, credibility, and professional integrity, there are other places.

"PopGun69" is a revered aluminium laminator of astrolabes on to TRIDENTs and MUST be respected for his contributions, etc....

We are what we are, and I do my best at all times to be respectful. I don't issue edicts as to behavior, or moral judgment on imaginary slights.

The reason I stay is because I know what it is. If anyone here flies pursuant to my opinions, they need a mental/medical. Likewise you. And all the others.

I keep my skin thick, my mouth reasonably clean, and practice respect.

My disrespect I reserve for machines, and you will have noticed I do not throw mud at the dead.

The a/c is a gd DEVICE. It is not someone's puppy, or girlfriend. Drama is best reserved to make a point, not to cast aspersions into the ether, at those who are unknown to the caster.

get a grip?

GarageYears

Lyingman: You've seen this > http://www.pprune.org/tech-log/46062...ml#post6650540

Tell me WEHRE in these traces does the THS NOT follow the ELEVATOR?

From 2.10.45 the elevators are continuously NU to some greater or lesser extent, but NU they stay. So does the THS... why wouldn't it?

Lyman

You are correct. Why do you ask me your question? It is the job of the THS to "follow the elevators". Agreed?


You find that appropriate? The thrust of my disagreement is not with you, but with the design.

Let me pose a question. Say that with the dgrd to AL2, the THS was inhibited, no "TRIM". In fact, no TRIM til Degaulle, and some mx attentions. Do you see a possibly better result?

I do. What do you think? Does the TRIM TANK have baffles? I honestly don't know? Will you make an attempt to understand my position?

Many here see a wall because the PF input NU. Because he did, they refuse to even discuss other possibilities.

447 is done. They are lost. Who is at fault? The only thing left is to change what we can, not fossilize ourselves in pointless personality attack.

"Lyingman"? Do you understand how immature that makes you appear?

airtren

Old Carthusian,

I appreciate the apology, as that puts us in line with interpreting the data, which means staying within the "technical" realm, and not the "how", or "why" I am interpreting the data the way I do, which is in the "personal" realm.

This thread is about discussing elements that members consider important, and pertinent to the AF 447 airplane accident, and your post was just that.

Therefore, my apology is due, if my sloppiness in writing my post has made it look more than simply an iteration of some of the content of the BEA Report.