AF 447 Thread No. 5
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by RetiredF4
The SS has an artificial feel, i did not deny that. It tells you stick deflected NU, than trim NU to equalize, or vice versa. Itīs not comparable to a tactile feedback (be it natural or artificial), where the amount of mistrim and therefore the amount of necessary correction can be felt in the hand on the stick due to stick deflection from neutral and force required to keep it deflected. It is therefore airload related feedback.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Since the a/c was almost immediately in "test pilot territory", what role could immediate Autotrim NU have played in a potential recovery? The THS, as takata has said, does not trim UP when g thresholds are exceeded. At the least, it would have provided a more immediate climb, and not required the PF to continue his ever increasing NU demands. Can't think of everything, I guess. That "Zoom" thing. We know that 330 can recover from STALL, it is patent.
Seems if this THS had not held back, the a/c would have STALLED with a great deal more energy in its airframe, perhaps emphatically dropping her nose, etc. The tail drag did them in.
then again, the safety record is exemplary.
It is assuredly coincidence, but when the THS was needed for climb, it was not available. Later, when it was not needed, it came back, and ruined the trajectory. Still later, it prevented a recovery by limiting elevator authority all the way down.
The way I see it
Seems if this THS had not held back, the a/c would have STALLED with a great deal more energy in its airframe, perhaps emphatically dropping her nose, etc. The tail drag did them in.
then again, the safety record is exemplary.
It is assuredly coincidence, but when the THS was needed for climb, it was not available. Later, when it was not needed, it came back, and ruined the trajectory. Still later, it prevented a recovery by limiting elevator authority all the way down.
The way I see it
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Lyman/Bearfoil
It is assuredly coincidence, but when the THS was needed for climb, it was not available. Later, when it was not needed, it came back, and ruined the trajectory. Still later, it prevented a recovery by limiting elevator authority all the way down.
The way I see it
The way I see it
It was, at first, quite hard for me to parse what you were saying exactly, but now, from a couple of your last post, it becomes perfectly clear again that your style and focus could not be so perfectly immited!
Are we going to chase our tails again on every mentioned subject?
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
takata
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
If this is illegal, then we say adieu.
If not, when you gather your thoughts, can you respond? You brought it up. The THS is dormant to help in the NU demand. Later, with a climb initiated, it activates and zooms the a/c.
BEA: At PITCH +10, the a/c started to climb, (they mean ascend?)
Are you willing to admit the THS has caused a problem? However unfortunate for the AB Philosophy, (It did as directed), do you have the stuffing to admit that whether the flying pilot knew or did not know, there is a problem when Autotrim interferes in an emergent maneuvering regime?
We have our own moderator, and he cares little for ruffled feathers. You have always seemed fair and passionate. Are you willing?
bon chance
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
If this is illegal, then we say adieu.
If not, when you gather your thoughts, can you respond? You brought it up. The THS is dormant to help in the NU demand. Later, with a climb initiated, it activates and zooms the a/c.
BEA: At PITCH +10, the a/c started to climb, (they mean ascend?)
Are you willing to admit the THS has caused a problem? However unfortunate for the AB Philosophy, (It did as directed), do you have the stuffing to admit that whether the flying pilot knew or did not know, there is a problem when Autotrim interferes in an emergent maneuvering regime?
We have our own moderator, and he cares little for ruffled feathers. You have always seemed fair and passionate. Are you willing?
bon chance
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Lyman
takata
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
If this is illegal, then we say adieu.
If not, when you gather your thoughts, can you respond? You brought it up. The THS is dormant to help in the NU demand. Later, with a climb initiated, it activates and zooms the a/c.
BEA: At PITCH +10, the a/c started to climb, (they mean ascend?)
We have our own moderator, and he cares little for ruffled feathers.
bon chance
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
If this is illegal, then we say adieu.
If not, when you gather your thoughts, can you respond? You brought it up. The THS is dormant to help in the NU demand. Later, with a climb initiated, it activates and zooms the a/c.
BEA: At PITCH +10, the a/c started to climb, (they mean ascend?)
We have our own moderator, and he cares little for ruffled feathers.
bon chance
Moreover, me (alone) absolutely never complained about your (multiple) identities!... and behavior to anyone (here, I meant moderators).
I just think that this is a very serious proof of something very wrong with yourself - your many "minds", objectives, agendas.... (including how many other clones?)
I won't complain either as I'm all for open free speech, and it's not my job to moderate you if you (and whoever) are unable to understand that.
My precious...!
Join Date: Jun 2009
Location: Paris
Posts: 691
Likes: 0
Received 0 Likes
on
0 Posts
Hi DJ77,
Yes. Which meant that when Captain moves his sidestick, there is no mechanical relation with F/O's position.
Hi PJ2,
How could this ND tendency be introduced if there was no way to change the pressure applied on the sidestick pitch axis?
My understanding is that sidesticks behave differently in auto mode and manual mode, hence will use different circuits. Documentation about those details is lacking in manuals (like many other details: find, for example, the detailed matrix of Airspeed, Alpha, etc; function monitoring).
"The two controllers are springloaded to neutral, and are not mechanically coupled."
Hi PJ2,
On landing, the Flare Law introduces a slight ND tendency, against which the pilot must pull, naturally creating the flare manoeuvre.
My understanding is that sidesticks behave differently in auto mode and manual mode, hence will use different circuits. Documentation about those details is lacking in manuals (like many other details: find, for example, the detailed matrix of Airspeed, Alpha, etc; function monitoring).
Join Date: Jun 2009
Location: somewhere
Posts: 451
Likes: 0
Received 0 Likes
on
0 Posts
SS artificial feel.
PJ2 & Takata:
There is NO feedback to SS.
Both roll and pitch channel have identical dampers.
Roll channel two rotary spring elements which ensures artificial feel.
Pitch channel two artificial feel spring rods.
The required artificial force in the pitch channel:
There is NO feedback to SS.
Both roll and pitch channel have identical dampers.
Roll channel two rotary spring elements which ensures artificial feel.
Pitch channel two artificial feel spring rods.
The required artificial force in the pitch channel:
Join Date: Aug 2011
Location: Frankfurt
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Hi everybody :-)
even though I am not a "flying" person other than sitting at the rear of a plane I've followed this long discussion with enormous interest.
Many questions turn around my head, but I will continue reading here to find some of them answered.
Nevertheless there is one point I would like to have answered: I love the computer, it's technical side as well and have no problem to understand, not all, but most of the problems which might arise. But I know that not only in my family but also among my friends, there are people who dislike using the PC, even though most of them have to use them at their work, in private they tell me after weeks "oh yeah, i have to go and look at my mail"
Now the profession of a pilot is first of all to know how to fly a plane, which in itself is already very demanding. But what about a person who loves to fly but has no interest or notion of a computer? He or she just doesn't understand what's it all about as he doesn't care. But in modern flying this is essential. When reading about the reaction of the PF I could not help wondering if he really understood the planes computer and everything connected with it.
Many questions turn around my head, but I will continue reading here to find some of them answered.
Nevertheless there is one point I would like to have answered: I love the computer, it's technical side as well and have no problem to understand, not all, but most of the problems which might arise. But I know that not only in my family but also among my friends, there are people who dislike using the PC, even though most of them have to use them at their work, in private they tell me after weeks "oh yeah, i have to go and look at my mail"
Now the profession of a pilot is first of all to know how to fly a plane, which in itself is already very demanding. But what about a person who loves to fly but has no interest or notion of a computer? He or she just doesn't understand what's it all about as he doesn't care. But in modern flying this is essential. When reading about the reaction of the PF I could not help wondering if he really understood the planes computer and everything connected with it.
Join Date: Jan 2005
Location: W of 30W
Posts: 1,916
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by PJ2
The Flare Law doesn't affect the stick, but it instead "rolls in" a bit of ND bias, against which the pilot must then pull.
Join Date: Apr 2011
Location: UK
Posts: 13
Likes: 0
Received 0 Likes
on
0 Posts
Lyman/Bearfoil wrote...
OMG - Bearfoil has evolved into some kind of HIVE-MIND!
Before you shoot off on another wild goose chase concerning the THS, make sure you understand what an "integral" term does in a time-domain control system. (or just look up "integration" on wikipedia). If you understand that, you will understand that the THS position was entirely correct and by-design during the incident.
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
Before you shoot off on another wild goose chase concerning the THS, make sure you understand what an "integral" term does in a time-domain control system. (or just look up "integration" on wikipedia). If you understand that, you will understand that the THS position was entirely correct and by-design during the incident.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Now the profession of a pilot is first of all to know how to fly a plane, which in itself is already very demanding. But what about a person who loves to fly but has no interest or notion of a computer? He or she just doesn't understand what's it all about as he doesn't care. But in modern flying this is essential. When reading about the reaction of the PF I could not help wondering if he really understood the planes computer and everything connected with it.
I dont think it's a case of the PF failing to understand the computer (which in this case, outside of autotrim, wasn't actively doing anything to assist his inputs anyway). He seems to have broken a few basic rules of aeronautics which remain the same whether you're in a Cessna, a 747 or an Airbus - chief among those being that you do not pull up into a stall warning*. Other contributing rules include "Do not make large control inputs at cruise level/at the limits of your aircraft's achievable altitude", and the basic rule of CRM, which is "ignore your co-pilot at your peril, doubly so if he or she has more experience than you".
The fact that the Airbus uses a computer to manage many of its functions is neither here nor there anyway - the fact is that if you are certified to fly an airliner and you have people in the back, it is incumbent upon you to know your aircraft's systems well, whether they consist of modern technology or cables, pulleys and bellcranks.
[* - By which I mean the stall warning that was sounding for nearly a minute before the AoA readings became unreliable, during which time he was still pulling up. ]
Join Date: Aug 2011
Location: Frankfurt
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
thanks Dozy for the welcome
and your explanation.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman
this is not comprehensible at all.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman
this is not comprehensible at all.
Join Date: Jan 2008
Location: uk
Posts: 857
Likes: 0
Received 0 Likes
on
0 Posts
http://www.pprune.org/rumours-news/4...ml#post6620025
The ship seemed fine at 2:10:05. What happened next (and is still happening, one fears), has to do with some basics, and that, as a pilot, is embarrassing.
I think it unlikely he would be reopening previous arguments after concluding in that way, and even more unlikely that it would be done hiding behind a different name - thin skin was not an attribute of the old bear.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Design
sd666
Hmmm.... The "performance as designed" is not in dispute. The THS did in fact, perform as designed. Clear? Because you like many others are stuck on "Design", and 'right' or 'wrong'.
It is, out the gate, quite possible, even likely, that the THS and the PF BOTH performed to "spec".
Fundamentally, the question is this.
The THS lay dormant for a time when the PF was attempting to climb the a/c. It is not programmed to TRIM NOSE UP when the airframe is experiencing g accelerations above, let us say, 1.25g.
The a/c, when the THS came back on line, was climbing, even rotatiing further NU. If unexpected, this could certainly create a "Zoom". A radical PITCH UP, and an unwanted extension of time in aspect (Climb).
So the THS started to TRIM NU from -3 to -13+ without stop, as the PF was still "stick back". Energy, both aerodynamic and ballistic, paid off and the a/c STALLED. Now, the THS is fully NOSE UP, and remained that way till impact. Insufficient ND from PF? Possibly. Stall warning when A/C was close to recover at each ND excursion? So we are told.
Finally, what is the a/c specific performance in Pitch with the elevators free and the THS full NU?
Elevators are sheltered from airflow in this configuration when deflected NOSE DOWN.
They are fully exposed to airflow in this configuration when deflected NOSE UP.
The THS in FULL NOSE UP is in and of itself a very powerful fixed full up Angle of INCIDENCE.
I can frame the question any of a number of other ways. It is meant to be clear and straightforward. Your thoughts?
Please do not feign exasperation to escape answering, as others do.
Again, the THS is not being questioned either as to Performance, or DESIGN.
Hmmm.... The "performance as designed" is not in dispute. The THS did in fact, perform as designed. Clear? Because you like many others are stuck on "Design", and 'right' or 'wrong'.
It is, out the gate, quite possible, even likely, that the THS and the PF BOTH performed to "spec".
Fundamentally, the question is this.
The THS lay dormant for a time when the PF was attempting to climb the a/c. It is not programmed to TRIM NOSE UP when the airframe is experiencing g accelerations above, let us say, 1.25g.
The a/c, when the THS came back on line, was climbing, even rotatiing further NU. If unexpected, this could certainly create a "Zoom". A radical PITCH UP, and an unwanted extension of time in aspect (Climb).
So the THS started to TRIM NU from -3 to -13+ without stop, as the PF was still "stick back". Energy, both aerodynamic and ballistic, paid off and the a/c STALLED. Now, the THS is fully NOSE UP, and remained that way till impact. Insufficient ND from PF? Possibly. Stall warning when A/C was close to recover at each ND excursion? So we are told.
Finally, what is the a/c specific performance in Pitch with the elevators free and the THS full NU?
Elevators are sheltered from airflow in this configuration when deflected NOSE DOWN.
They are fully exposed to airflow in this configuration when deflected NOSE UP.
The THS in FULL NOSE UP is in and of itself a very powerful fixed full up Angle of INCIDENCE.
I can frame the question any of a number of other ways. It is meant to be clear and straightforward. Your thoughts?
Please do not feign exasperation to escape answering, as others do.
Again, the THS is not being questioned either as to Performance, or DESIGN.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
and your explanation.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman this is not comprehensible at all.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman
this is not comprehensible at all.The difficulties in the Captain re-taking his seat are as follows however:
- The PNF, who seemed to have a pretty good grasp of the situation, yet sadly did not feel the ability to directly intervene was sitting in the Captain's seat. Technically the Captain could have taken the PF's seat, but in doing so would have been putting himself in a position where he wasn't as familiar with the controls as he was in the left-hand seat.
- The two F/Os had been at the controls as the situation was developing and as such, the Captain was unaware of what had led up to the situation - it would have been reasonable for him to assume that the F/Os had better situational awareness than he did at that point (though it was a sadly misplaced assumption)
- The aircraft was pitching and rolling to a significant degree. Exchanging seats at that point would have been difficult and probably would have taken a significant amount of time, and as such could have put them in more danger than they were in already as far as the Captain knew.
Personally I think that the logic for not re-taking a seat at the controls was understandable. What bothers me is the fact that he felt it OK to leave two F/O's, one of whom was fairly junior and probably still a little demob-happy (having just returned from vacation) in charge as the aircraft was transiting a known problem weather area.
[@if789 - I got a very well-written and heartfelt PM from bearfoil just after the report was published, expressing an understanding that human error was probably the largest contributing factor, and a desire to take some time away from the forum - nevertheless he was back on less than 24 hours later having picked up sonething CONF said about control logic and saying that it couldn't have been the pilots' fault again. ]
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,777
Likes: 0
Received 0 Likes
on
0 Posts
Hi,
More:
http://www.pprune.org/tech-log/45687...ml#post6630926
Originally Posted by Jutta 
and your explanation.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman
this is not comprehensible at all.
and your explanation.
What I found very disturbing was the fact that the CDB, when he came back into the CP, did not take his seat immediately. Even if I understand that there are certain rules which have to be followed. But the situation was exceptional, he must have felt that!? Both the captain and other co-pilot put their lives into the hands of a person who was visibly in a lot of stress, mildly expressed. For a laywoman
this is not comprehensible at all.
http://www.pprune.org/tech-log/45687...ml#post6630926
Join Date: Mar 2006
Location: Choroni, sometimes
Posts: 1,974
Likes: 0
Received 0 Likes
on
0 Posts
Artificial pitch feel
Please enlighten me.
Is it a function of elevator load?
Or is it just a spring rod, no matter if the aircraft is in a stall or at 340 knots?
Thx
Please enlighten me.
Is it a function of elevator load?
Or is it just a spring rod, no matter if the aircraft is in a stall or at 340 knots?
Thx