AF 447 Thread No. 9
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"No evidence there would be any gain?" What a wild statement.
Last edited by DozyWannabe; 13th Jul 2012 at 18:07.
Hello TD;
Re post #330:
Yes, you're correct - the TLs would be in the CLB detent already. The drill merely ensures that this is so, just in case they have been moved out of the detent for any reason.
Yes, again correct - the Thrust Lock would synchronize with the aircraft parameter at the time of disconnect. Eighty-four percent is sufficient to maintain stable flight for the time needed to bring out the QRH, (which should always be right at hand). The page hasn't changed in quite some time, (2.21 in Nav Abnormals). In fact a five-degree pitch attitude results in a gentle climb of around 800 to 1200fpm, (again, I was wrong on the original statements) - for an experienced crew, this would not present a problem as "close to nothing" has changed and one can return to level stable flight with tiny movements on the stick and observing the altitude and altitude trend, (rate of change). Digital vice analogue adds a cognitive step because the notion of "amount-to or -away from" is missing - no big deal.
No, your logic is sound - it takes a significant change in pitch or power to place the aircraft at risk of overspeed or stall during this drill. The settings given are very close to what the aircraft would require but they're not exact. Going from recollection of the FCTM here...I think an answer lies in the 10T weight category intervals. The FCTM does state that the settings are approximate and that fine-tuning involves monitoring altitude using either indicated or GPS altitude:
LEVEL OFF AND STABILIZATION (IF REQUIRED)
The table gives the proper pitch and thrust values to stabilize level flight according to weight and altitude.
If the altitude information is unreliable, the FPV and V/S are also affected. In this case, the GPS altitude, if available, is the only means to confirm whether the aircraft is maintaining level flight.
When the altitude information is reliable, use the FPV.
If the FPV is reliable, or if the GPS altitude is available:
‐ Maintain level flight (FPV on the horizon or constant GPS altitude)
‐ Adjust thrust according to the table
‐ Observe the resulting pitch attitude, and compare it with the recommended pitch target in the table:
• If the pitch necessary to maintain level flight is above the table's pitch target, the aircraft is slow, then increase thrust,
• If the pitch necessary to maintain level flight is below the table's pitch target, the aircraft is fast, then decrease thrust.
When the pitch required to maintain level flight gets close to the table's pitch target, re-adjust thrust according to table's thrust target.
This technique permits to stabilize the speed quickly while maintaining level flight.
If the FPV is not reliable and the GPS altitude is not available (no means to ensure level flight):
Adjust pitch and thrust according to table values, and wait for speed stabilization. Expect a significant time to stabilize and important altitude variations during the stabilization.
Hope this helps.
Re post #330:
My first questions would be aren't the thrust levers already in the climb detent? Does the thrust lock latch a 84% N1? if so, does this give much time to figure the right pitch and power setting before a real stall warning occurs?
Yes, again correct - the Thrust Lock would synchronize with the aircraft parameter at the time of disconnect. Eighty-four percent is sufficient to maintain stable flight for the time needed to bring out the QRH, (which should always be right at hand). The page hasn't changed in quite some time, (2.21 in Nav Abnormals). In fact a five-degree pitch attitude results in a gentle climb of around 800 to 1200fpm, (again, I was wrong on the original statements) - for an experienced crew, this would not present a problem as "close to nothing" has changed and one can return to level stable flight with tiny movements on the stick and observing the altitude and altitude trend, (rate of change). Digital vice analogue adds a cognitive step because the notion of "amount-to or -away from" is missing - no big deal.
But when I see the tables, the reset for pitch is 3.5º and 90% N1 for a M of .82 based on altitude and weight. This seems a little low on N1% with a 3.5º pitch setting based on what is referenced in the BEA report for level flight at the altitude being experienced. I recognize at the upper end of the power settings at 350 there isn't much power left to be had, but the differences seem confusing to me more than anything, perhaps I am missing some finer points. Any thoughts? Is my logic off?
LEVEL OFF AND STABILIZATION (IF REQUIRED)
The table gives the proper pitch and thrust values to stabilize level flight according to weight and altitude.
If the altitude information is unreliable, the FPV and V/S are also affected. In this case, the GPS altitude, if available, is the only means to confirm whether the aircraft is maintaining level flight.
When the altitude information is reliable, use the FPV.
If the FPV is reliable, or if the GPS altitude is available:
‐ Maintain level flight (FPV on the horizon or constant GPS altitude)
‐ Adjust thrust according to the table
‐ Observe the resulting pitch attitude, and compare it with the recommended pitch target in the table:
• If the pitch necessary to maintain level flight is above the table's pitch target, the aircraft is slow, then increase thrust,
• If the pitch necessary to maintain level flight is below the table's pitch target, the aircraft is fast, then decrease thrust.
When the pitch required to maintain level flight gets close to the table's pitch target, re-adjust thrust according to table's thrust target.
This technique permits to stabilize the speed quickly while maintaining level flight.
If the FPV is not reliable and the GPS altitude is not available (no means to ensure level flight):
Adjust pitch and thrust according to table values, and wait for speed stabilization. Expect a significant time to stabilize and important altitude variations during the stabilization.
Hope this helps.
That is a huuuuge way from M0,8 or 0,82 from a kinetic energy perspective.
So even at 84% you're lightyears awy from a stall.
It takes a significant climb to shed that energy. Thrust variation (short of a shut-down) has much less immediate impact on kinetic energy than a climb. If simply keeping altitude you have ample time to sort things out.
Edit: Stall warning would come on earler especially in Alt Law but with a constant altitude it should come up somewhere around 230 kts (M0,65 - 0,7)
Last edited by henra; 13th Jul 2012 at 18:37.
PJ, thank you very much, and also thanks to TD and henra for some amplifying thoughts.
I better understand what was, what is, and an idea for "what ought to be."
The industry as a whole, who fly AB 330's, will hopefully come to a consensus on a "best practice" regarding this malfunction family. What I gather from your observations is that perhaps the consensus has not yet been achieved.
I better understand what was, what is, and an idea for "what ought to be."
The industry as a whole, who fly AB 330's, will hopefully come to a consensus on a "best practice" regarding this malfunction family. What I gather from your observations is that perhaps the consensus has not yet been achieved.
Last edited by Lonewolf_50; 13th Jul 2012 at 19:13.
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Hi DozyWannabe,
Please see Page 105 of the final report:
"1.16.8.3 Response to aural warnings
Numerous studies have been conducted on insensitivity to aural warnings and they showed that the aggressive nature, rarity and unreliability of these warnings may lead operators to ignore these signals [1, 2]. In particular, in the event of a heavy workload, insensitivity to aural warnings may be caused by a conflict between these warnings and the cognitive tasks in progress. The ability to turn one’s attention to this information is very wasteful as this requires the use of cognitive resources already engaged on the current task. The performance of one of these tasks (solving the problem or taking the warning into account) or of both would be affected [3].
In addition, studies on the visual-auditory conflict show a natural tendency to favour visual to auditory perception when information that is contradictory and conflicting, or seen as such, of both senses is presented [4, 5, and 6]. Piloting, calling heavily on visual activity, could lead pilots to a type of auditory insensitivity to the appearance of aural warnings that are rare and in contradiction with cockpit information.
A recent study in electrophysiology on a piloting task seems to confirm that the appearance of such visual-auditory conflicts in a heavy workload situation translates into an attention selectivity mechanism that favours visual information and leads to disregarding critical aural warnings [7]."
Having the stall warning alert only via the auditory channel is not a good design during high work load situations.
If you were busy arguing with Lyman in a noisy party and I wanted to get your attention, the most effective way would be by touch (on your arm or shoulder say). It's a completely separate channel with no competition from any other warning - as is the stick shaker.
...and the same could be said of the Airbus auditory/visual warnings. Unsurprisingly, in training situations, pilots respond well to both.
"1.16.8.3 Response to aural warnings
Numerous studies have been conducted on insensitivity to aural warnings and they showed that the aggressive nature, rarity and unreliability of these warnings may lead operators to ignore these signals [1, 2]. In particular, in the event of a heavy workload, insensitivity to aural warnings may be caused by a conflict between these warnings and the cognitive tasks in progress. The ability to turn one’s attention to this information is very wasteful as this requires the use of cognitive resources already engaged on the current task. The performance of one of these tasks (solving the problem or taking the warning into account) or of both would be affected [3].
In addition, studies on the visual-auditory conflict show a natural tendency to favour visual to auditory perception when information that is contradictory and conflicting, or seen as such, of both senses is presented [4, 5, and 6]. Piloting, calling heavily on visual activity, could lead pilots to a type of auditory insensitivity to the appearance of aural warnings that are rare and in contradiction with cockpit information.
A recent study in electrophysiology on a piloting task seems to confirm that the appearance of such visual-auditory conflicts in a heavy workload situation translates into an attention selectivity mechanism that favours visual information and leads to disregarding critical aural warnings [7]."
Having the stall warning alert only via the auditory channel is not a good design during high work load situations.
If you were busy arguing with Lyman in a noisy party and I wanted to get your attention, the most effective way would be by touch (on your arm or shoulder say). It's a completely separate channel with no competition from any other warning - as is the stick shaker.
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From what I've read I don't believe that Dozy was saying a Stick Shaker wouldn't benefit. Simply that you can't look at it from your armchair and say "that's the solution". You need to look at the whole system and work out the pros and cons. If I read the report correctly, in this tragic situation the pilot ignored the aural warning, ignored the instruments and even ignored the other pilot in the cockpit. He had become fixated completely and if he was ignoring all of those I would guess, and it is a guess, he had a mental picture where he no longer believed what the systems were telling him, if that is the case then there is a real possibility he would have ignored the stick shaker as a false indication too.
As for the crowded noisey room scenario, have you ever tried to break up a fight just by tapping someone on the shoulder?
I will also question why some people on this thread are obsessed with a stick shaker. This aircraft had a system that could have safely restored level flight had it been re-engaged. So, instead of putting a stick shaker in, why not allow the system to take control again if it is convinced that the aircraft is in danger of exiting the envelope?
The system is designed to respect principles that have been held sacred for several decades. The safety analysis is extremely stringent and forces decisions into the design that when analysed against a very specific set of conditions doesn't seem to make sense. If you step back and look at the whole picture, with all the analysis at your disposal, it makes more sense. Of course nothing is perfect, and it takes such events as this to expose weaknesses in the design decisions. However in these cases it is very rare for the fix to be simple. The system has to be re-analysed.
I have read a lot of comments on these threads, many seem to be from people who, from what they've written, appear to have never been involved in designing, clearing and certifying a complex avionic system. But even in their position of ignorance they are quite happy to throw rocks at the Airbus design team.
In my view of this tragic event, the aircraft let down the pilot by suddenly exposing him to a set of conditions that caused him to lose situational awareness and expecting him to run with it. The pilot let down the aircraft by not carrying out the basic tasks required to return the aircraft to safe steady flight. The reasons this happened are no doubt deep and wide going way beyond just the pilot and the aircraft, the lessons will be many and varied and hopefully will lead to changes that improve safety all round.
What scares me is for how little a span of time the airspeed was unreliable and how quickly this event went from routine to catastrophic. What saddens me is that perhaps in 99 time out of 100 this pilot would have correctly interpreted the situation and it would have become a none event.
As for the crowded noisey room scenario, have you ever tried to break up a fight just by tapping someone on the shoulder?
I will also question why some people on this thread are obsessed with a stick shaker. This aircraft had a system that could have safely restored level flight had it been re-engaged. So, instead of putting a stick shaker in, why not allow the system to take control again if it is convinced that the aircraft is in danger of exiting the envelope?
The system is designed to respect principles that have been held sacred for several decades. The safety analysis is extremely stringent and forces decisions into the design that when analysed against a very specific set of conditions doesn't seem to make sense. If you step back and look at the whole picture, with all the analysis at your disposal, it makes more sense. Of course nothing is perfect, and it takes such events as this to expose weaknesses in the design decisions. However in these cases it is very rare for the fix to be simple. The system has to be re-analysed.
I have read a lot of comments on these threads, many seem to be from people who, from what they've written, appear to have never been involved in designing, clearing and certifying a complex avionic system. But even in their position of ignorance they are quite happy to throw rocks at the Airbus design team.
In my view of this tragic event, the aircraft let down the pilot by suddenly exposing him to a set of conditions that caused him to lose situational awareness and expecting him to run with it. The pilot let down the aircraft by not carrying out the basic tasks required to return the aircraft to safe steady flight. The reasons this happened are no doubt deep and wide going way beyond just the pilot and the aircraft, the lessons will be many and varied and hopefully will lead to changes that improve safety all round.
What scares me is for how little a span of time the airspeed was unreliable and how quickly this event went from routine to catastrophic. What saddens me is that perhaps in 99 time out of 100 this pilot would have correctly interpreted the situation and it would have become a none event.
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If you were busy arguing with Lyman in a noisy party and I wanted to get your attention, the most effective way would be by touch (on your arm or shoulder say). It's a completely separate channel with no competition from any other warning - as is the stick shaker.
I'm well aware of the theory that the tactile channel - as separate and distinct from audio-visual - can get attention when audio-visual can't, and it makes sense in terms of pure logic and psychology. This doesn't alter the fact that in times of high stress workload in the flight deck, shakers have been ignored multiple times. The only way to know for certain would be to blind-test the two methods, but I don't see that happening any time soon.
Last edited by DozyWannabe; 13th Jul 2012 at 20:11.
Ladies and gentlemen, dear PPRuNers, honourable participants in our discussion, I would like to take an opportunity to kindly ask you to get acquainted with The Book:
It will do you a lot of good and also might help reduce the PPRuNe bandwidth wastage.
If you have third edition on your bookshelf, you might find the following chapters useful:
Pg 109, Stalling, which shows that pilots' wildly divergent views on the subject of stalling have preceded PPRuNe by decades. Also displays DP Davies fantastic ability of insight, in matters not just technical but also in human nature.
Pg 128, Stick shakers.
Pg 130, Stick pushers.
Stickshakers are not supposed to be universal stall warning devices! They are fitted to aeroplanes that have no pronounced natural pre-stall buffet or margin between buffet and stall is to thin for buffet to be used as effective deterrent. Why A330 doesn't have it installed? Two possible clues in the final report.
So 330 both shakes out of her own accord and did receive some special dispensation in certification process by virtue of her envelope protection.
Now about stick pusher: it is not stall recovery device, it is stall prevention device! It has to be fitted to aeroplanes with unacceptable stall characteristics. e.g. pitch-up at stall or prone to entering the deep stall. As anything else related to aeroplanes, while solving some problems, they bring in some problems of their own (HTBJ, pg 131) so claiming they are stall recovery devices and suggesting they should be installed on any aeroplane to deal with the problem of distracted crew would be sparkling display of aeronautical ignorance.
Since for nine years I have been earning my daily bread flying the aeroplanes equipped with both stick shakers and stick pushers, implying if I ignored the stall warnings and somehow pulled them into stall they would bite without warning and once stalled would stand good chance to be unrecoverable, one might perchance find understandable that I view the propositions to indiscriminately train each & every airline pilot in full stall recovery procedure with considerable amusement.
Yea... it was measly 13 degrees. Far too high for cruise anyway but compatible with the ardent desire to climb and having no idea aeroplane has insufficient performance to fulfill her masters wish - yet she attempted to obey into her eventual destruction.
Emphasis is mine but this is one of the most precise hitting the nail on the head that can be found on the PPRuNe.
Maybe it's just me, but when someone counters to spectacularly wrong theory with some solid facts disproving it, least I expect it would mean the end of that particular direction of discussion.
Sorry Dozy, I missed the part where this was discussed. Could you provide the reference that states latching of ALT2 permanently disables the autopilot? I need to get my head around this.
It will do you a lot of good and also might help reduce the PPRuNe bandwidth wastage.
If you have third edition on your bookshelf, you might find the following chapters useful:
Pg 109, Stalling, which shows that pilots' wildly divergent views on the subject of stalling have preceded PPRuNe by decades. Also displays DP Davies fantastic ability of insight, in matters not just technical but also in human nature.
Pg 128, Stick shakers.
Pg 130, Stick pushers.
Stickshakers are not supposed to be universal stall warning devices! They are fitted to aeroplanes that have no pronounced natural pre-stall buffet or margin between buffet and stall is to thin for buffet to be used as effective deterrent. Why A330 doesn't have it installed? Two possible clues in the final report.
Originally Posted by BEA Final report on AF447, English version, page 93
Airbus subsequently flew special flights to collect more accurate data at high angles
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat.
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat.
Originally Posted by BEA Final report on AF447, English version, page 187
When there are no protections left, the aeroplane no longer possesses positive
longitudinal static stability even on approach to stall. This absence specifically results
in the fact that it is not necessary to make or increase a nose-up input to compensate
for a loss of speed while maintaining aeroplane altitude. This behaviour, even if it
may appear contrary to some provisions in the basic regulations, was judged to be
acceptable by the certification authorities by taking into account special conditions
and interpretation material. Indeed, the presence of flight envelope protections
makes neutral longitudinal static stability acceptable.
longitudinal static stability even on approach to stall. This absence specifically results
in the fact that it is not necessary to make or increase a nose-up input to compensate
for a loss of speed while maintaining aeroplane altitude. This behaviour, even if it
may appear contrary to some provisions in the basic regulations, was judged to be
acceptable by the certification authorities by taking into account special conditions
and interpretation material. Indeed, the presence of flight envelope protections
makes neutral longitudinal static stability acceptable.
Now about stick pusher: it is not stall recovery device, it is stall prevention device! It has to be fitted to aeroplanes with unacceptable stall characteristics. e.g. pitch-up at stall or prone to entering the deep stall. As anything else related to aeroplanes, while solving some problems, they bring in some problems of their own (HTBJ, pg 131) so claiming they are stall recovery devices and suggesting they should be installed on any aeroplane to deal with the problem of distracted crew would be sparkling display of aeronautical ignorance.
Since for nine years I have been earning my daily bread flying the aeroplanes equipped with both stick shakers and stick pushers, implying if I ignored the stall warnings and somehow pulled them into stall they would bite without warning and once stalled would stand good chance to be unrecoverable, one might perchance find understandable that I view the propositions to indiscriminately train each & every airline pilot in full stall recovery procedure with considerable amusement.
Originally Posted by Lyman
Your "15" degrees PITCH UP I believe came from the DFDR, via ins and archive. You know the Pitch attained was not nearly that high, in the initial command post a/p loss.
Originally Posted by Ok 465
727 2-engine out, manual reversion, NDB approach to NDB minimums was essentially a one maneuver check-ride.
What was most interesting, was not who succeeded or failed at the maneuver, but who would be enthusiastically willing to attempt it.
What was most interesting, was not who succeeded or failed at the maneuver, but who would be enthusiastically willing to attempt it.
Originally Posted by lyman
Look, Sir, it is getting tiresome that you expect to make a glib comment about a failure of some piece of equipment and expect others to accept your pronouncement as 'end of discussion'.
Originally Posted by DozyWannabe
he AP will not re-engage itself automatically in any scenario, and because Alt2 was triggered and latched in the case of AF447 even a manual attempt to re-engage AP would have been denied.
Lets not get too deep into the helpfulness of stick shakers.
There is some unique combinations at play in this accident
For starters its at high altitude and preceded by speed drop outs.
My feeling is that if only the stick shaker had annunciated, the crew would likely have addressed that bit somewhat better. But when multiple annunciations are alerted the tendancy of some might be to go to lowest common denominator in their memory bank ( and forget about the stick shaker or auto-something disconect)
I've seen this happen before
There is some unique combinations at play in this accident
For starters its at high altitude and preceded by speed drop outs.
My feeling is that if only the stick shaker had annunciated, the crew would likely have addressed that bit somewhat better. But when multiple annunciations are alerted the tendancy of some might be to go to lowest common denominator in their memory bank ( and forget about the stick shaker or auto-something disconect)
I've seen this happen before
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What scares me is for how little a span of time the airspeed was unreliable and how quickly this event went from routine to catastrophic. What saddens me is that perhaps in 99 time out of 100 this pilot would have correctly interpreted the situation and it would have become a none event.
What is needed for a auto control flight like in the Airbus to automatically go in a mode (one more law
) "pitch and power" in case of UAS ?Can this be implemented ... for avoid the "1%" pilot failure to set the famous "pitch and power" ....
Last edited by jcjeant; 13th Jul 2012 at 21:04.
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Stick shakers help because you immediately release the back pressure or decrease bank angle to stop it. I had it happen at night in a 727 over the water held high with speed brakes and a 30 degree bank circling to keep the pattern tight to lose altitude landing at POP in the Dominican Republic. The speed was fine but the bank and speed brakes set it off.
You instinctively fix the situation not ever experiencing it in an airplane, only the sim during training. It would definately override any oral warning.
You instinctively fix the situation not ever experiencing it in an airplane, only the sim during training. It would definately override any oral warning.
jceant, #344
This is really the common thread of what i've been thinking in terms
of a system that should be designed to degrade more gracefully at
the edges. When all the standard "protections" fail, there should be
absolute limits in command inputs that cannot be exceeded to ensure the
safety of the aircraft.
With so much technology built into these machines, it amazes me that there
are so many corners where the pilot can get himself into serious trouble,
for whatever reason. The acceptable limits under all conditions of flight
are known, so there's no technical reason why such last line of defense
protections shouldn't be built into the system design.
Perhaps they never thought it could never happen, but it does...
Indeed .. and the solution was simple ... and repeated by many here
"Pitch and power". What is needed for a auto control flight like in
the Airbus to automatically go in a mode (one more law ) "pitch and
power" in case of UAS ?. Can this be implemented ... for avoid the
"1%" pilot failure to set the famous "pitch and power" ....
"Pitch and power". What is needed for a auto control flight like in
the Airbus to automatically go in a mode (one more law ) "pitch and
power" in case of UAS ?. Can this be implemented ... for avoid the
"1%" pilot failure to set the famous "pitch and power" ....
of a system that should be designed to degrade more gracefully at
the edges. When all the standard "protections" fail, there should be
absolute limits in command inputs that cannot be exceeded to ensure the
safety of the aircraft.
With so much technology built into these machines, it amazes me that there
are so many corners where the pilot can get himself into serious trouble,
for whatever reason. The acceptable limits under all conditions of flight
are known, so there's no technical reason why such last line of defense
protections shouldn't be built into the system design.
Perhaps they never thought it could never happen, but it does...
Last edited by syseng68k; 13th Jul 2012 at 21:44.
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Clandestino;
It has been posted a number of times, but it was takata in AF447 - Thread No.5. I think A33Zab has also had something to say on the latching of ALT2B.
EDIT :: If you are looking for an AI definitive reference, then I have not been able to find it in FCOM or Instructor Training Manuals, so assume that it will be hidden somewhere in the AMM.
Could you provide the reference that states latching of ALT2 permanently disables the autopilot?
EDIT :: If you are looking for an AI definitive reference, then I have not been able to find it in FCOM or Instructor Training Manuals, so assume that it will be hidden somewhere in the AMM.
Last edited by mm43; 13th Jul 2012 at 22:34.
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Originally Posted by Clandestino
Now about stick pusher: it is not stall recovery device, it is stall prevention device!
From HTBJ page 111 (my bold):
Hence, on aeroplanes capable of super-stalling, the 'stall' speed needs to be positively identified by a completely unmistakable, sharp, forward movement of the control column causing the aeroplane immediately to pitch down and reduce its incidence.
... the pusher is required to work only when the wing arrives at its 'stalling' incidence ...
Last edited by HazelNuts39; 13th Jul 2012 at 22:56.
Thanks mm43, takata discussed the reasons for latching the alt law but I am looking for the confirmation of notion that has made circles around this thread lately: namely that latching of ALT2B disables the autopilot until ground reset. What logically follows is that since other crews normally used autopilot while remaining in ALT mode after regaining the normal airspeed display, they never got as far as ALT2B and AF447 was pretty unique. However, pretty old FCOM I have shows ADR disagreement doesn't result in AP being lost, so I'm looking for further reference.
Maybe semantic but it looks to me like a scope issue.
Maybe a bit semantic
Originally Posted by DP Davies
If a stick pusher is used to meet the stall requirements it must provide two qualities: clear and unmistakable identification of the stall, by a sharp positive forward movement of a control column, and an adequate nose down pitch by the aircraft.
(...)
It is obvious that those constructors forced to use stick pusher, installations did so because they either found that their natural stall was quite unacceptable, or were not prepared to investigate the aeroplane's qualities beyond Max. Cl by other than a small margin, or decided that some part of their structure could not take the hammering in the violent buffet before the nose drop.
It follows form all these considerations, therefore, that that the stick pusher must always prevent the natural stall being reached in service.
(...)
It is obvious that those constructors forced to use stick pusher, installations did so because they either found that their natural stall was quite unacceptable, or were not prepared to investigate the aeroplane's qualities beyond Max. Cl by other than a small margin, or decided that some part of their structure could not take the hammering in the violent buffet before the nose drop.
It follows form all these considerations, therefore, that that the stick pusher must always prevent the natural stall being reached in service.
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It follows form all these considerations, therefore, that that the stick pusher must always prevent the natural stall being reached in service.
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Clandestino...
"Maybe it's just me, but when someone counters to spectacularly wrong theory with some solid facts disproving it, least I expect it would mean the end of that particular direction of discussion."
No solid facts were in evidence, merely a retort that a shaker had on occasion been ignored. Further, even BEA had trouble identifying Buffet and had to with accelerometer data from DFDR.
The dispensation you reference is what is galling. Do you honestly think the shaker would have been without possible benefit on 447?
The 330 in this case showed signs of Buffet only two seconds after the SW fired.
You are without doubt an expert, and I admire and respect your knowledge. Your personality is of no concern to me, I actually enjoy your posturing and preening. I expect that in a good pilot.
"Maybe it's just me, but when someone counters to spectacularly wrong theory with some solid facts disproving it, least I expect it would mean the end of that particular direction of discussion."
No solid facts were in evidence, merely a retort that a shaker had on occasion been ignored. Further, even BEA had trouble identifying Buffet and had to with accelerometer data from DFDR.
The dispensation you reference is what is galling. Do you honestly think the shaker would have been without possible benefit on 447?
The 330 in this case showed signs of Buffet only two seconds after the SW fired.
You are without doubt an expert, and I admire and respect your knowledge. Your personality is of no concern to me, I actually enjoy your posturing and preening. I expect that in a good pilot.
WRT "mixing" baro and inertial.
Regarding the concept of "mixing" baro and inertial (as posted above).
I would suggest, that such an idea, in a unreliable baro situation,
(which has caused the AP to disconnect in the first place), is,
stupidity personified.
Regarding the concept of "mixing" baro and inertial (as posted above).
I would suggest, that such an idea, in a unreliable baro situation,
(which has caused the AP to disconnect in the first place), is,
stupidity personified.
faulty source continues to be used, but that tracking the two sources
on a continuous basis provides a more accurate view of the overall
situation, a potentially earlier warning of developing problems and
fallback in the event of a single source failure. Perhaps i'm not very
good at decribing what i'm trying to get across ?.
If you have an ivsi on the panel, then you are already using baro /
inertial mixing, though not in a particularly complex way.
Why "contaminate" a supposedly "good" source of reliable data (inertial) with "known" or "suspect" baro data ?
All you end up with is a new layer of "uncertainty", on top of the one you already have, which you then have to troubleshoot.
Why make an uncertain situation even more uncertain and harder to troubleshoot ?
Such a situation is self defeating.
In a crisis, you need "crystal clear deliniation" of what is "good" from what is "suspect", or "bad".
The system should clearly "split" the two data sets by source.
Baro says "this", inertial says "that".
All you end up with is a new layer of "uncertainty", on top of the one you already have, which you then have to troubleshoot.
Why make an uncertain situation even more uncertain and harder to troubleshoot ?
Such a situation is self defeating.
In a crisis, you need "crystal clear deliniation" of what is "good" from what is "suspect", or "bad".
The system should clearly "split" the two data sets by source.
Baro says "this", inertial says "that".
validity and consistency of data.
That can be done very simply.
Upon AP disconnect, the system should automatically, and instantly, modify the PFD to show all good inertial data, and remove the suspect data, as follows:
(a) remove FD bars if they were on, and
(b) put up the "inertial" FPV (bird) [with the inertial GS (not CAS or TAS or MN - they are baro) in the circle], and
(c) on the right of the bird - display the "actual" AOA, ("baro-ish" - but - we need it) and
(d) on the left of the bird - display the "target" AOA (for altitude, weight and speed from database - should be the same as the QRH - UAS tables).
(e) on the right - below the bird - display the "actual" N1's
(f) on the left - below the bird - display the "target" N1's (for altitude, weight and speed from database - should be the same as the QRH - UAS tables).
(g) in the left lower corner of the PFD - display a circular "traditional steam gauge" altimeter with a moving hand driven by inertial data, and
(h) in the right lower corner of the PFD - display a circular "traditional steam gauge" variometer with moving hand driven by inertial data.
PF should then just simply fly the bloody aeroplane.
Upon AP disconnect, the system should automatically, and instantly, modify the PFD to show all good inertial data, and remove the suspect data, as follows:
(a) remove FD bars if they were on, and
(b) put up the "inertial" FPV (bird) [with the inertial GS (not CAS or TAS or MN - they are baro) in the circle], and
(c) on the right of the bird - display the "actual" AOA, ("baro-ish" - but - we need it) and
(d) on the left of the bird - display the "target" AOA (for altitude, weight and speed from database - should be the same as the QRH - UAS tables).
(e) on the right - below the bird - display the "actual" N1's
(f) on the left - below the bird - display the "target" N1's (for altitude, weight and speed from database - should be the same as the QRH - UAS tables).
(g) in the left lower corner of the PFD - display a circular "traditional steam gauge" altimeter with a moving hand driven by inertial data, and
(h) in the right lower corner of the PFD - display a circular "traditional steam gauge" variometer with moving hand driven by inertial data.
PF should then just simply fly the bloody aeroplane.
about the last line though :-)...