AF 447 Thread No. 9
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TD. PITCH AND POWER was used, and it kept them stalled. Reducing thrust would not have helped? You are strict on sequence, did you not get my point?
Reducing thrust and pushing the stick forward would not have recovered the flight path, according to BEA, unless you maintain that this crew was exceptionally clever, and not average Line. So yes, the issue was they were lost at STALL, the rest is truly irrelevant to the accident, but not to us....
Why do you bring up TWA800, it is insulting. I am no conspiracist. You think listening to the entire CVR would add nothing to the PUBLIC perception of the pilots' actions? Now that is truly remote.
In saying that prior events should be isolated from the one we see, I am speaking of crew action, it is always the problem, since humans can and do misunderstand, make huge blunders (727-200). What did the crew do that was unique? Mechanically, the idea is that repetition is far more insightful, machines do not take abstract thought, and are of course different in that it requires a differ and unique analysis for recommendations.
Sad for this flight that the FDs were not turned off? It is outrageous, in my opinion. I am of the opinion that the crew were unaware they dealt with UAS for precious seconds, and made decisions based on their belief that NORMAL LAW obtained, and this is what started the crucial disconnect between the PF SS and actual PITCH.
The sidestick conveys no information, either by position or feel, and losing track of one's inputs over time can be profoundly confusing. Without an instrument to track PITCH, ( And there is NO instrument for AoA data) , the a/c was utterly doomed. Now people say that PITCH data was available, but there is no positive proof, and it is not disallowed to consider that the pilots were put in the weeds by a partial, or missing, panel full of reliable data.
May I see an artifact or image that shows an horizon? I'll wait.
Yes theory. I take your point re: practical realities. Are you saying the BEA report is a compromise? It is, but I would not mind hearing it from you, you are esteemed from my vantage point, and not without good reason!
Reducing thrust and pushing the stick forward would not have recovered the flight path, according to BEA, unless you maintain that this crew was exceptionally clever, and not average Line. So yes, the issue was they were lost at STALL, the rest is truly irrelevant to the accident, but not to us....
Why do you bring up TWA800, it is insulting. I am no conspiracist. You think listening to the entire CVR would add nothing to the PUBLIC perception of the pilots' actions? Now that is truly remote.
In saying that prior events should be isolated from the one we see, I am speaking of crew action, it is always the problem, since humans can and do misunderstand, make huge blunders (727-200). What did the crew do that was unique? Mechanically, the idea is that repetition is far more insightful, machines do not take abstract thought, and are of course different in that it requires a differ and unique analysis for recommendations.
Sad for this flight that the FDs were not turned off? It is outrageous, in my opinion. I am of the opinion that the crew were unaware they dealt with UAS for precious seconds, and made decisions based on their belief that NORMAL LAW obtained, and this is what started the crucial disconnect between the PF SS and actual PITCH.
The sidestick conveys no information, either by position or feel, and losing track of one's inputs over time can be profoundly confusing. Without an instrument to track PITCH, ( And there is NO instrument for AoA data) , the a/c was utterly doomed. Now people say that PITCH data was available, but there is no positive proof, and it is not disallowed to consider that the pilots were put in the weeds by a partial, or missing, panel full of reliable data.
May I see an artifact or image that shows an horizon? I'll wait.
Yes theory. I take your point re: practical realities. Are you saying the BEA report is a compromise? It is, but I would not mind hearing it from you, you are esteemed from my vantage point, and not without good reason!
HazelNuts
I think BEA is saying that, if this was a movie you had been watching, at this point you would give up all hope of a happy ending.
EDIT: What was lacking was 'a good understanding of the situation'. With that they should have known what to do about it, and would not need a 'purpose' to do it. The quote is from the part of the BEA report that is "mainly based on the results of the work of the Human Factors group". IMO it speaks more of the HF than of airframe technicalities.
I think BEA is saying that, if this was a movie you had been watching, at this point you would give up all hope of a happy ending.
EDIT: What was lacking was 'a good understanding of the situation'. With that they should have known what to do about it, and would not need a 'purpose' to do it. The quote is from the part of the BEA report that is "mainly based on the results of the work of the Human Factors group". IMO it speaks more of the HF than of airframe technicalities.
I cited the discussed matter word for word out of the BEA Final report, or do you have a different one? It does not cover the creation of a script for a movie, but this report is the work of experts with a lot more data at hand than we ever will, created over a two year period for the sake of safety. .
What evidence do you have, that it is the result of the human factor group, which is covered in the report under point 1.16.8?
The above cited statements from BEA is found under
2. Analysis
2.1 Accident Scenario
2.1.3 From the triggering of the STALL 2 warning until the end of the flight
Bolding by me
2.1.3.5 End of the flight
At about 2 h 12, descending though FL 315, the aeroplane’s angle of attack was established around an average value of about 40 degrees. Only an extremely purposeful crew with a good comprehension of the situation could have carried out a manoeuvre that would have made it possible to perhaps recover control of the aeroplane. In fact, the crew had almost completely lost control of the situation.
Up until the end of the flight, no valid angle of attack value was less than 35°.
At about 2 h 12, descending though FL 315, the aeroplane’s angle of attack was established around an average value of about 40 degrees. Only an extremely purposeful crew with a good comprehension of the situation could have carried out a manoeuvre that would have made it possible to perhaps recover control of the aeroplane. In fact, the crew had almost completely lost control of the situation.
Up until the end of the flight, no valid angle of attack value was less than 35°.
Last edited by RetiredF4; 30th Jul 2012 at 16:21.
Lyman
I am of the opinion that the crew were unaware they dealt with UAS for precious seconds, and made decisions based on their belief that NORMAL LAW obtained, and this is what started the crucial disconnect between the PF SS and actual PITCH.
I am of the opinion that the crew were unaware they dealt with UAS for precious seconds, and made decisions based on their belief that NORMAL LAW obtained, and this is what started the crucial disconnect between the PF SS and actual PITCH.
BEA 2.1.2.4 Identification of the situation
..........In the case of the accident, the crew did not associate the loss of displayed speeds and the associated procedure. This may be explained by the difference between the symptoms that appeared during the training session that they had followed a few months previously and those that appeared during the event. In particular, the high number of ECAM messages that the PNF called out should be compared with the absence of messages in the training session scenario......
.......In the absence of a specific message expressing detection of unreliable speed by the systems, the crew was unable to identify any logical link between the symptoms perceived and these ECAM messages. The impression of an accumulation of failures created as a result probably did not incite the crew to link the anomaly with a particular procedure, in this case the “Vol avec IAS douteuse” procedure........
.........The symptoms perceived may therefore have been considered by the crew as anomalies to add to the anomaly of the airspeed indication, and thus indicative of a much more complex overall problem than simply the loss of airspeed information.
..........In the case of the accident, the crew did not associate the loss of displayed speeds and the associated procedure. This may be explained by the difference between the symptoms that appeared during the training session that they had followed a few months previously and those that appeared during the event. In particular, the high number of ECAM messages that the PNF called out should be compared with the absence of messages in the training session scenario......
.......In the absence of a specific message expressing detection of unreliable speed by the systems, the crew was unable to identify any logical link between the symptoms perceived and these ECAM messages. The impression of an accumulation of failures created as a result probably did not incite the crew to link the anomaly with a particular procedure, in this case the “Vol avec IAS douteuse” procedure........
.........The symptoms perceived may therefore have been considered by the crew as anomalies to add to the anomaly of the airspeed indication, and thus indicative of a much more complex overall problem than simply the loss of airspeed information.
Incomplete excerpt, bolding by me, please read the report for full version
BEA 3.1 Findings
......
Although having identified and called out the loss of the airspeed indications, neither of the two copilots called the “Unreliable IAS” procedure.
ˆˆThe Flight Directors did not disconnect.
ˆˆThe crossbars disappeared and then re-appeared on several occasions, changing mode several times.
.......
BEA 3.2 Causes of the Accident
These events can be explained by a combination of the following factors:
......
The lack of a clear display in the cockpit of the airspeed inconsistencies identified by the computers;
......
Flight Director indications that may led the crew to believe that their actions were appropriate, even though they were not
......
The difficulty in recognizing and understanding the implications of a reconfiguration in alternate law with no angle of attack protection.
......
Although having identified and called out the loss of the airspeed indications, neither of the two copilots called the “Unreliable IAS” procedure.
ˆˆThe Flight Directors did not disconnect.
ˆˆThe crossbars disappeared and then re-appeared on several occasions, changing mode several times.
.......
BEA 3.2 Causes of the Accident
These events can be explained by a combination of the following factors:
......
The lack of a clear display in the cockpit of the airspeed inconsistencies identified by the computers;
......
Flight Director indications that may led the crew to believe that their actions were appropriate, even though they were not
......
The difficulty in recognizing and understanding the implications of a reconfiguration in alternate law with no angle of attack protection.
Last edited by RetiredF4; 30th Jul 2012 at 16:52.
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Lyman;
Ballistic, in my vocabulary, is zero 'g'. Figure 66 of the final report shows the variation of normal acceleration prior to, and through the stall. Prior to the the stall warning, the PF push on the SS in response to the PNF's urging resulted in less than 1g. Then the PF started to pull, increasing the LF to 1.13 g until the airplane stalled. The stall resulted in (was associated with) a large increase in drag, which caused the subsequent steep descent without an increase in airspeed.
RetiredF4;
You're taking my post out of context. I was responding to BOAC's question: What do you think? The issue was whether BEA intended to say that FL315 was the last point where recovery was possible.
The aircraft has climbed after the lift ceiling was passed, it was converting energy to altitude without benefit of aerodynamic lift, IOW, Ballistic. There was no drastic increases in drag, in fact drag was decreasing, due to the lessening of velocity.
RetiredF4;
You're taking my post out of context. I was responding to BOAC's question: What do you think? The issue was whether BEA intended to say that FL315 was the last point where recovery was possible.
2 - ANALYSIS
2.1 Accident Scenario
This part is mainly based on the results of the work of the Human Factors group, whose approach is described in paragraph 1.16.8.
2.1 Accident Scenario
This part is mainly based on the results of the work of the Human Factors group, whose approach is described in paragraph 1.16.8.
Hazelnuts
RetiredF4;
You're taking my post out of context. I was responding to BOAC's question: What do you think? The issue was whether BEA intended to say that FL315 was the last point where recovery was possible.
RetiredF4;
You're taking my post out of context. I was responding to BOAC's question: What do you think? The issue was whether BEA intended to say that FL315 was the last point where recovery was possible.
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Originally Posted by Lyman
I still believe the crash was a foregone conclusion within fifteen seconds after loss of autopilot.
It means the captain had 90 seconds to correctly evaluate the situation before taking or directing the corrective actions.
But first things first, the BEA had to evaluate what was the influence of the autotrim in the process.
Take the same airplane, one with no autotrim under stall warning, one which trims almost to the stop.
Before developing HF the BEA had to first extensively analyze the technical aspects ... Instead of that they kept silent on what Airbus is not interested to see discussed.
HN39 (#859), I had considered that the first stall warning could have been an artifact of the ADC changeover, but ‘real’ as you describe does not alter the thrust of my view (#816).
The important inference was that (at least) the PF decided that this alert represented a real stall and commenced the erroneous action, even though we know (in hindsight) that a warning would not be given in normal law. I surmise that the PF did not consider this, nor re-evaluate the situation even when the PNF called the Alt Law condition. The PF may never have appreciated the change in control law as his attention was fixed on the erroneous ‘stall recovery’ pull up manoeuvre.
Do you mean they did not associate the UAS procedure with the UAS situation?
Yes, this supposition is supported by the crew reports from previous incidents. The loss of an airspeed display in itself is not ‘unreliable’ – it’s not there, reliability as such cannot be judged (unreliable might mean it’s not there very often).
This may be playing with semantics, but it is an exploration of how the PF might have interpreted the situation, or how this procedure might have been taught which then influenced the assessment.
IIRC the distant history of the UAS drill probably came from accidents involving flight without airspeed, was this taught. Or perhaps the UAS training was done against the backdrop of ice crystal icing, a completely different context. Therefore there may not have been an immediate association between loss of an airspeed display and a drill relating to ‘ice crystals’ and aircraft handling.
The important inference was that (at least) the PF decided that this alert represented a real stall and commenced the erroneous action, even though we know (in hindsight) that a warning would not be given in normal law. I surmise that the PF did not consider this, nor re-evaluate the situation even when the PNF called the Alt Law condition. The PF may never have appreciated the change in control law as his attention was fixed on the erroneous ‘stall recovery’ pull up manoeuvre.
Do you mean they did not associate the UAS procedure with the UAS situation?
Yes, this supposition is supported by the crew reports from previous incidents. The loss of an airspeed display in itself is not ‘unreliable’ – it’s not there, reliability as such cannot be judged (unreliable might mean it’s not there very often).
This may be playing with semantics, but it is an exploration of how the PF might have interpreted the situation, or how this procedure might have been taught which then influenced the assessment.
IIRC the distant history of the UAS drill probably came from accidents involving flight without airspeed, was this taught. Or perhaps the UAS training was done against the backdrop of ice crystal icing, a completely different context. Therefore there may not have been an immediate association between loss of an airspeed display and a drill relating to ‘ice crystals’ and aircraft handling.
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I am going to need a rewind here again, I'm afraid:
a) References appearing to the Airbus 'stall recovery pull-up' manouevre. Is this right?
b) References to the fact that the stall warning 'cannot' sound in Normal Law. Is this right?
c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
Putting these together, this means, does it not, that it is considered 'correct' to pull up as hard as you like at the 'stall' in Alt Law where you might have no stall protection? I am just not understanding why the logic of all the years of aviation is suddenly overturned. I do hope I have got this wrong.
a) References appearing to the Airbus 'stall recovery pull-up' manouevre. Is this right?
b) References to the fact that the stall warning 'cannot' sound in Normal Law. Is this right?
c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
Putting these together, this means, does it not, that it is considered 'correct' to pull up as hard as you like at the 'stall' in Alt Law where you might have no stall protection? I am just not understanding why the logic of all the years of aviation is suddenly overturned. I do hope I have got this wrong.
BOAC, it seems to me, from the information I have available, that the audio warning of a stall* begins before the wing actually stalls, in terms of the AoA value that triggers the crickets. Since the crew can't see their AoA, they must rely on such a trigger to become aware of an impending stall if they don't realize that they are approaching one.
(* = or warning of impending stall)
I reached back to find some info on PPRuNe discussion on alpha floor, and am interested in how confusing references to it seem to remain.
(* = or warning of impending stall)
c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
Posts: 339 Alpha Floor is an Autothrust mode that selects Full Power to prevent the a/c from stalling. Full power is maintained and even with full back stick the a/c will not stall. The max angle of attack is Alpha max and in normal law (normal flight mode) this can not be exceded.
http://www.pprune.org/questions/8386...tml#post798663
http://www.pprune.org/tech-log/35588...ml#post4611937
http://www.pprune.org/questions/4705...ml#post6836119
http://www.pprune.org/questions/8386...tml#post798663
http://www.pprune.org/tech-log/35588...ml#post4611937
http://www.pprune.org/questions/4705...ml#post6836119
Last edited by Lonewolf_50; 30th Jul 2012 at 18:34.
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Safetypee;
IMHO you are reversing cause and effect.
Loss of airspeed display means that you have to manage flight without it. In cruise that means maintaining current attitude and power setting, not pulling to climb.
the PF decided that this alert represented a real stall and commenced the erroneous action
Therefore there may not have been an immediate association between loss of an airspeed display and a drill relating to ‘ice crystals’ and aircraft handling.
BOAC,
A. My reference to this considered that there was an ‘invented’ stall recovery procedure in normal law involving a pull up because the protections were there (#816).
B. AFAIK, correct.
C. AFAIK, correct.
Thus combining A (on the premise of B) with C, and due to poor situation assessment, surprise, inappropriate training, application of automation, etc, the PF pulled up believing that the aircraft had stalled at the time of speed failure, the resulting climb did actually stall the aircraft. Then by supposition, the ‘normal law’ mindset maintained the control input resulting in complete confusion, particularly when back stick stopped the stall warning and forward stick started it (AoA cut-out logic).
HN39 “IMHO you are reversing cause and effect.” Hence my consideration of the ADC, or even turbulence / poor handling with the lower stall threshold?
“Loss of speed …”, I agree, but if the mindset was that of ‘a higher priority’ stall warning, then what?
A. My reference to this considered that there was an ‘invented’ stall recovery procedure in normal law involving a pull up because the protections were there (#816).
B. AFAIK, correct.
C. AFAIK, correct.
Thus combining A (on the premise of B) with C, and due to poor situation assessment, surprise, inappropriate training, application of automation, etc, the PF pulled up believing that the aircraft had stalled at the time of speed failure, the resulting climb did actually stall the aircraft. Then by supposition, the ‘normal law’ mindset maintained the control input resulting in complete confusion, particularly when back stick stopped the stall warning and forward stick started it (AoA cut-out logic).
HN39 “IMHO you are reversing cause and effect.”
Hence my consideration of the ADC, or even turbulence / poor handling with the lower stall threshold?“Loss of speed …”, I agree, but if the mindset was that of ‘a higher priority’ stall warning, then what?
HazelNuts
RetiredF4;
What do you think? Is the BEA saying that no recovery was possible after passing through FL315?
RetiredF4;
What do you think? Is the BEA saying that no recovery was possible after passing through FL315?
Last edited by RetiredF4; 30th Jul 2012 at 18:52.
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a) References appearing to the Airbus 'stall recovery pull-up' manouevre. Is this right?
No doubt if I have that wrong in any particular the flak will fly
b) References to the fact that the stall warning 'cannot' sound in Normal Law. Is this right?
c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
BOAC, it seems to me, from the information I have available, that the audio warning of a stall* begins before the wing actually stalls, in terms of the AoA value that triggers the crickets? Since the crew can't see their AoA, they must rely on such a trigger to become aware of an impending stall.
(* = or warning of impending stall)
(* = or warning of impending stall)
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CONFiture...
"Quote:
Originally Posted by Lyman
I still believe the crash was a foregone conclusion within fifteen seconds after loss of autopilot.
Hi... I am more or less in agreement with BEA, in fact, I am unwinding their conclusions to include the errant climb, vis a vis the skill/perception quotient.
At one point I was willing to say that the flight path was recoverable perhaps immediately, from the beginning of the descent from apogee. I have seen it done, never in an airliner, which means I am choppless in the discussion.
HazelNuts39.... For purposes of discussion, words like "apogee" and momentum, suggest ballistic influences. Totally Ballistic? It depends, everything is subject to gravity in our environment, BEA suggest the wing has passed its ceiling, just after Power passed its, and. Omentum caused the a/c to continue climbing. Where is the "drastic increase in Drag" Clandestino points up? Certainly not drag from lift exchanges, or do I read BEA incorrectly? The pilot keeps the NOSE UP after limits pass, and starts descending, at virtually identical AoA, so where is the conversion of loss of lift to lowering of the airframe's nose? I suggest that "0" gravity is not possible in any portion of the trajectory, only exceedance and shortfall, so less than "1" suggests ballistic is at work. "Descent" is the result of gravity, always, yes? In any case, My take on the regime around apogee is that the a/c was already Stalled, if your definition is the wings have stopped lifting?
And my conclusion from that is that the pilots were unaware that a Stall had taken place?
One cannot escape the impression forced upon us by the relevant and released data, this crew were not up to UAS recovery in these conditions. That means the discussion should practically revolve around crew, CRM, and flight data issues.
The mechanical/electrical/avionical (?) is there as well, and since there is incomplete data involved for any conclusions, BEA have removed these areas from discussion, IMO. More's the pity, also IMO.
"Quote:
Originally Posted by Lyman
I still believe the crash was a foregone conclusion within fifteen seconds after loss of autopilot.
Hi... I am more or less in agreement with BEA, in fact, I am unwinding their conclusions to include the errant climb, vis a vis the skill/perception quotient.
At one point I was willing to say that the flight path was recoverable perhaps immediately, from the beginning of the descent from apogee. I have seen it done, never in an airliner, which means I am choppless in the discussion.
HazelNuts39.... For purposes of discussion, words like "apogee" and momentum, suggest ballistic influences. Totally Ballistic? It depends, everything is subject to gravity in our environment, BEA suggest the wing has passed its ceiling, just after Power passed its, and. Omentum caused the a/c to continue climbing. Where is the "drastic increase in Drag" Clandestino points up? Certainly not drag from lift exchanges, or do I read BEA incorrectly? The pilot keeps the NOSE UP after limits pass, and starts descending, at virtually identical AoA, so where is the conversion of loss of lift to lowering of the airframe's nose? I suggest that "0" gravity is not possible in any portion of the trajectory, only exceedance and shortfall, so less than "1" suggests ballistic is at work. "Descent" is the result of gravity, always, yes? In any case, My take on the regime around apogee is that the a/c was already Stalled, if your definition is the wings have stopped lifting?
And my conclusion from that is that the pilots were unaware that a Stall had taken place?
One cannot escape the impression forced upon us by the relevant and released data, this crew were not up to UAS recovery in these conditions. That means the discussion should practically revolve around crew, CRM, and flight data issues.
The mechanical/electrical/avionical (?) is there as well, and since there is incomplete data involved for any conclusions, BEA have removed these areas from discussion, IMO. More's the pity, also IMO.
Last edited by Lyman; 30th Jul 2012 at 18:56.
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c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
According to Clandestino, Alternate Law handling is trained to assume a worst-case scenario (i.e. all protections lost).
As I (a non-pilot) understand it, there has been a commonly (A+B) accepted drill for "approach to stall recovery" which involves application of power and sometimes a pull-up to minimise altitude loss? Now both A & B are saying that this approach can lead to confusion and possible accidents...
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BOAC,
Re (a): From Annex 11 to BEA FR:
Re (b): In normal law, stall warning is not inhibited, but the threshold for its occurrence is set at 23 degrees, whereas the High AoA protection does not allow AoA greater than alphamax (approx. 14.5 degrees at low Mach, 5.2 degrees at M.8) (all in clean configuration).
Re (c): The alpha-floor protection is inoperative in Alternate law (FCOM 1.27.30)
Re (a): From Annex 11 to BEA FR:
Stall Warning
At lift-off:
(...)
During any other flight phases after lift-off:
Thrust levers: ... TOGA
At the same time:
Pitch attitude ... Reduce
(...)
At lift-off:
(...)
During any other flight phases after lift-off:
Thrust levers: ... TOGA
At the same time:
Pitch attitude ... Reduce
(...)
Re (c): The alpha-floor protection is inoperative in Alternate law (FCOM 1.27.30)
Last edited by HazelNuts39; 30th Jul 2012 at 19:28.
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One is the AB GPWS escape procedure - namely pull the stick back to the stops and alpha-prot plus alpha-floor will automatically give you climb performance (without risk of stall) that you would need a sky god to get on a conventional a/c. Nowt to do with stall recovery or 447 though.
Second is the practice noted by BEA and others before of emphasising minimum altitude loss in (approach-to) stall recovery, and perhaps teaching stall as a speed problem not an AOA problem. That is an industry problem though, not an AB problem.
b) References to the fact that the stall warning 'cannot' sound in Normal Law. Is this right?
I suspect that it is true to say the by the time you hear the stall warning you are not in normal law...
EDIT: disregard the bit above, it's memory playing tricks (i.e. it's b***ocks). I sit corrected.
c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?
Alpha floor is, as far as I know, not active in any law outside Normal [maybe on some AB type - but I don't think so].
Putting these together, this means, does it not, that it is considered 'correct' to pull up as hard as you like at the 'stall' in Alt Law where you might have no stall protection? I am just not understanding why the logic of all the years of aviation is suddenly overturned. I do hope I have got this wrong.
Something, however, made this crew think it was correct to pull (and Colgan and Ethiopian and many others further back)...
Last edited by infrequentflyer789; 30th Jul 2012 at 21:39.
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My confession is that I believe PF was not utilizing a version of "pull back hard it will not Stall..." I think he was honestly trying to regain a cruise Pitch or thereabouts. I do not think he was instantly on board with UAS, and all that it demanded. Whether he sussed it ever is arguable. The data is insufficient to make a perfect conclusion.
So I agree with Infrequentflyer. This accident is not well understood, but it does not suggest that anything like it will occur at all, ever.
bubbers, by " not well understood " I mean by me.
So I agree with Infrequentflyer. This accident is not well understood, but it does not suggest that anything like it will occur at all, ever.
bubbers, by " not well understood " I mean by me.
Infrequentflyer
Arguable. Stall warning can trigger in normal law, but I believe the immediate effect will be a law degradation. In normal law the system thinks it is keeping within the envelope, plus a margin, so this is a "should not happen". If it does happen, the system is going to drop envelope protections because it is clear the envelope simply isn't where it was thought to be...
I suspect that it is true to say the by the time you hear the stall warning you are not in normal law...
Arguable. Stall warning can trigger in normal law, but I believe the immediate effect will be a law degradation. In normal law the system thinks it is keeping within the envelope, plus a margin, so this is a "should not happen". If it does happen, the system is going to drop envelope protections because it is clear the envelope simply isn't where it was thought to be...
I suspect that it is true to say the by the time you hear the stall warning you are not in normal law...
reference BEA FR Appendix 11