AF 447 Thread No. 10
Lonewolf_50;
I agree.
Of more importance, and to Lyman's observation of the crew's comment regarding having been "nose-up 'for a while' ", the inability on the part of all three crew members to assess as a stalled condition the high rate of descent which could not be arrested by pitching the nose up is, (as well as the absence of effective CRM and the lack of SOPs), set the pathway to this accident.
IMO, somatogravatic illusion is a red herring in this particular case.
Of more importance, and to Lyman's observation of the crew's comment regarding having been "nose-up 'for a while' ", the inability on the part of all three crew members to assess as a stalled condition the high rate of descent which could not be arrested by pitching the nose up is, (as well as the absence of effective CRM and the lack of SOPs), set the pathway to this accident.
Gotta go with PJ2. Wolf and Lyman and others......
I have previously praised the aero characteristics of plane that made a stall so benign. Many planes would have been rocking/shuddering or even having uncontrollable roll. Then there's the attitude that " I can't stall this plane", not appreciating the reversion laws and such. Hence the comment about having kept the nose up for such a long time to no effect.
Besides that, what bothers me most is the initial reaction and initial control inputs. Why not just "hold what you have'? So the flight directors may have provided bad cues and the crew blindly followed them.
I, too, would appreciate a post from Andy as to the sim ride using the AF447 initial conditions. Was it set up after the loss of the A/P? Was it set up immediately prior to loss of the/ A/P? How much had Andy read about the whole profile? In other words, did the sim IP not say that this would duplicate AF447 but simply failed some air data inputs to get the A/P to disconnect? and the beat goes on....
the inability on the part of all three crew members to assess as a stalled condition the high rate of descent which could not be arrested by pitching the nose up is, (as well as the absence of effective CRM and the lack of SOPs), set the pathway to this accident.
Besides that, what bothers me most is the initial reaction and initial control inputs. Why not just "hold what you have'? So the flight directors may have provided bad cues and the crew blindly followed them.
I, too, would appreciate a post from Andy as to the sim ride using the AF447 initial conditions. Was it set up after the loss of the A/P? Was it set up immediately prior to loss of the/ A/P? How much had Andy read about the whole profile? In other words, did the sim IP not say that this would duplicate AF447 but simply failed some air data inputs to get the A/P to disconnect? and the beat goes on....
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@ alogobotur: I do.
I have no clue if it's been published in english, but here (and also here) are some comments about it I wrote at the time.
I concur with roulishollandais: the final report is better (but was released later). The book is an analysis based on what looks like (smells like, feels like) a leaded early draft of the CVR transcript.
@ Lonewolf_50 re: "IMO, somatogravatic illusion is a red herring in this particular case." ==>
I have no clue if it's been published in english, but here (and also here) are some comments about it I wrote at the time.
I concur with roulishollandais: the final report is better (but was released later). The book is an analysis based on what looks like (smells like, feels like) a leaded early draft of the CVR transcript.
@ Lonewolf_50 re: "IMO, somatogravatic illusion is a red herring in this particular case." ==>
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Correct me if I'm misremembering, but wasn't there a school of thought that had the PF misdiagnosing the buffeting - particularly the unusual airflow noise - as an indication of overspeed (or "crazy speed" as he put it)?
Last edited by DozyWannabe; 21st Feb 2013 at 17:42.
Correct, Doze, about the reference to a mach/high speed buffet. I can't read minds, especially those of ghosts, so the comment about "crazy speed" is still puzzling.
I discount confusion about the turbulence, as seems most of use can easily tell the diference between "chop" and an airframe buffet ( high or low speed). My own experience with approach to stall in the bent wing birds is that the buffet/burble/shaking is a lot different than turbulence in a storm or near a storm or even "light chop" you see in clear air when near the tropo boundary or the edge of the jet stream. Departure in the VooDoo was prefaced with noticeable buffet and wing rock. The SLUF also shook and rocked. The Deuce was as smooth as silk and the only thing you felt was a buzz ( could hear it, also). Next thing you knew you had the VVI pegged going down until you released back pressure and moved the stick forward.
and so the saga continues, heh heh
I discount confusion about the turbulence, as seems most of use can easily tell the diference between "chop" and an airframe buffet ( high or low speed). My own experience with approach to stall in the bent wing birds is that the buffet/burble/shaking is a lot different than turbulence in a storm or near a storm or even "light chop" you see in clear air when near the tropo boundary or the edge of the jet stream. Departure in the VooDoo was prefaced with noticeable buffet and wing rock. The SLUF also shook and rocked. The Deuce was as smooth as silk and the only thing you felt was a buzz ( could hear it, also). Next thing you knew you had the VVI pegged going down until you released back pressure and moved the stick forward.
and so the saga continues, heh heh
Last edited by gums; 21st Feb 2013 at 18:09.
Dozy, I recall a few threads ago some detailed discussion on what the PF may have heard, and what may have fed him a false input into his SA via the audio channel. (If that sound registered, why not the cricket chirp of the Stall Warning, one wonders? )
With that considered, the A330 was bopping along at something near to Mach 0.8, which doubtless has a sound signature to it if you are in the cockpit. As the initial climb was underway, might there have been a subtle decrease in that ambient noise? As I have no time in the front seat of an A330 at cruise, I have no idea how noticeable that auditory cue would be for a given pilot, nor how subtle or obvious a change in noise related to the change in speed as the aircraft slows down before the stall.
Would the air flow, once stalled, of the plane falling at somewhere around 10-14,000 feet per minute have the same audible signature? I don't know. I can't recall if anyone had a good answer for that.
But it's somewhat irrelevant, other than as a distraction to the primary task of instrument flying at altitude. To establish SA, the noise is a secondary cue related to the information on the primary flight instruments. (FPV addressed by gums up a few posts). So even though this issue of auditory data input has been raised, we are back to disorientation in the visual domain, in terms of a good (or bad) instrument scan and seeing, as well as grasping, (or not) the information displayed on the primary flight instruments.
I am aware of how attuned most pilots are in the auditory channel. Our ears often tell us of a state change, or alerts us to start looking for indication of a change due to "that doesn't sound right." So I won't poo poo the idea that the audio domain may have contributed to disorientation in this case.
In my experience, a change in the sound of something (often engines, or for the rotary winged bretheren the sound of the rotors changing as well as engines) gets your attention and gets you busy until you either fix what's wrong, or at least satisfy yourself that you know "what doesn't sound right."
The CVR doesn't give us much in terms of any discussion they had along those lines, but that doesn't mean neither pilot was dealing with that. It will remain an unknown.
With that considered, the A330 was bopping along at something near to Mach 0.8, which doubtless has a sound signature to it if you are in the cockpit. As the initial climb was underway, might there have been a subtle decrease in that ambient noise? As I have no time in the front seat of an A330 at cruise, I have no idea how noticeable that auditory cue would be for a given pilot, nor how subtle or obvious a change in noise related to the change in speed as the aircraft slows down before the stall.
Would the air flow, once stalled, of the plane falling at somewhere around 10-14,000 feet per minute have the same audible signature? I don't know. I can't recall if anyone had a good answer for that.
But it's somewhat irrelevant, other than as a distraction to the primary task of instrument flying at altitude. To establish SA, the noise is a secondary cue related to the information on the primary flight instruments. (FPV addressed by gums up a few posts). So even though this issue of auditory data input has been raised, we are back to disorientation in the visual domain, in terms of a good (or bad) instrument scan and seeing, as well as grasping, (or not) the information displayed on the primary flight instruments.
I am aware of how attuned most pilots are in the auditory channel. Our ears often tell us of a state change, or alerts us to start looking for indication of a change due to "that doesn't sound right." So I won't poo poo the idea that the audio domain may have contributed to disorientation in this case.
In my experience, a change in the sound of something (often engines, or for the rotary winged bretheren the sound of the rotors changing as well as engines) gets your attention and gets you busy until you either fix what's wrong, or at least satisfy yourself that you know "what doesn't sound right."
The CVR doesn't give us much in terms of any discussion they had along those lines, but that doesn't mean neither pilot was dealing with that. It will remain an unknown.
Last edited by Lonewolf_50; 21st Feb 2013 at 18:20.
Initial pitch-up
Quote from gums:
"...what bothers me most is the initial reaction and initial control inputs. Why not just "hold what you have'? So the flight directors may have provided bad cues and the crew blindly followed them."
This is the crux of the matter. What I think we can say beyond reasonable doubt is that the PF cannot have made a conscious decision to climb a significant amount above FL350. That he allowed a sustained climb seems inexplicable.
But one thing still bugs me: that sudden INDICATED loss of 300ft caused by the sudden drop of INDICATED IAS/CAS (my deliberate tautology). Pilots are generally unhappy to find they have lost (or gained) that much height in the cruise. The initial reaction may be to recover it asap, however unnecessary that haste may seem. Could this explain the PF's initial stick movement, if not the magnitude of it? If so, his subsequent preoccupation with roll control in roll-direct, and the startle factor causing him to tense up, may go some way to explaining his apparent inability to recognise his inappropriate pitch-up input, and correct it.
"...what bothers me most is the initial reaction and initial control inputs. Why not just "hold what you have'? So the flight directors may have provided bad cues and the crew blindly followed them."
This is the crux of the matter. What I think we can say beyond reasonable doubt is that the PF cannot have made a conscious decision to climb a significant amount above FL350. That he allowed a sustained climb seems inexplicable.
But one thing still bugs me: that sudden INDICATED loss of 300ft caused by the sudden drop of INDICATED IAS/CAS (my deliberate tautology). Pilots are generally unhappy to find they have lost (or gained) that much height in the cruise. The initial reaction may be to recover it asap, however unnecessary that haste may seem. Could this explain the PF's initial stick movement, if not the magnitude of it? If so, his subsequent preoccupation with roll control in roll-direct, and the startle factor causing him to tense up, may go some way to explaining his apparent inability to recognise his inappropriate pitch-up input, and correct it.
Last edited by Chris Scott; 21st Feb 2013 at 19:05.
Hello Chris;
Yes, I think there is something to that in examining the data in the initial 12 to 14 seconds of the initiating (UAS) event. However, the altitude indication returned to FL350 within that time frame the pitch achieved was 10deg NU and rapidly increasing. The fact that no one who is experienced at flying these transports would maintain or even continue such attitudes and/or control inputs is sufficient I think to indicate a rapid loss of SA in terms of what transport aircraft are like to fly at cruise altitudes/high Mach numbers. A rapid return to nominal pitch attitudes in the first 20, possibly 30 seconds would have begun the stabilization process.
After the loss of energy and the increase of the AoA to about 6deg, the nose would have had to have been lowered say, to 5deg ND or even lower, for an effective initial attempt at recovery.
The air at cruise altitudes is, as we all are aware, very thin and the damping effects much reduced compared to the thicker air say, at FL200 so a long time would be needed to stabilize the airplane at that point.
At that point, the only awareness that would have saved the flight was an awareness that the wing was stalled. For a pilot who never hand-flew and who was raised and trained on auto-flight systems and who would never have seen a pitch attitude of say, -10 or -15deg, pointing the airplane down that far with an-already dramatically high VS would have been extremely challenging, but it was the only way to save the airplane.
It is gratifying to hear of so many changes being quietly implemented in training regimes and re-arranged priorities as a result of this tragic accident. That said, knowing how to fly a jet transport airplane using pitch and power in all flight regimes, normal and abnormal, is absolutely, fundamentally paramount in this business, period. Computers and autoflight are huge safety tools but are high-speed idiots that are dumber than a bag o' hammers when it comes to actually flying an airplane.
But one thing still bugs me: that sudden INDICATED loss of 300ft caused by the sudden drop of INDICATED IAS/CAS (my deliberate tautology). Pilots are generally unhappy to find they have lost (or gained) that much height in the cruise. The initial reaction may be to recover it asap, however unnecessary that haste may seem. Could this explain the PF's initial stick movement, if not the magnitude of it? If so, his subsequent preoccupation with roll control in roll-direct, and the startle factor causing him to tense up, may go some way to explaining his apparent inability to recognise his inappropriate pitch-up input, and correct it.
After the loss of energy and the increase of the AoA to about 6deg, the nose would have had to have been lowered say, to 5deg ND or even lower, for an effective initial attempt at recovery.
The air at cruise altitudes is, as we all are aware, very thin and the damping effects much reduced compared to the thicker air say, at FL200 so a long time would be needed to stabilize the airplane at that point.
At that point, the only awareness that would have saved the flight was an awareness that the wing was stalled. For a pilot who never hand-flew and who was raised and trained on auto-flight systems and who would never have seen a pitch attitude of say, -10 or -15deg, pointing the airplane down that far with an-already dramatically high VS would have been extremely challenging, but it was the only way to save the airplane.
It is gratifying to hear of so many changes being quietly implemented in training regimes and re-arranged priorities as a result of this tragic accident. That said, knowing how to fly a jet transport airplane using pitch and power in all flight regimes, normal and abnormal, is absolutely, fundamentally paramount in this business, period. Computers and autoflight are huge safety tools but are high-speed idiots that are dumber than a bag o' hammers when it comes to actually flying an airplane.
Hi PJ2,
That's a cogent analysis of the first half minute; a longer time frame than I had in mind. I think the loss of situational awareness becomes indisputable round about FL352 climbing, with the absence of any attempt to arrest the increasing pitch-attitude, let alone reverse it.
Quote:
"...knowing how to fly a jet transport airplane using pitch and power in all flight regimes, normal and abnormal, is absolutely, fundamentally paramount in this business, period."
Amen to that. Those of us who have hand-flown jets in the cruise for long periods know only too well that a single degree of pitch represents nearly 1000 ft/min (rather more on Concorde...). Practising it without the luxury of the FD, with or without IAS display, needs at least to be encouraged. That would best include a step-climb at CLB thrust with IAS, and a step-descent.
Lonewolf_50,
I reckon that, as you suggest, the audio signature would have changed considerably as the aircraft slowed down: engine noise gradually becoming more apparent as the air noise diminished. But, whereas subtle changes in sound can attract attention when you are relaxed, I suspect that they might not when the adrenalin is running?
That's a cogent analysis of the first half minute; a longer time frame than I had in mind. I think the loss of situational awareness becomes indisputable round about FL352 climbing, with the absence of any attempt to arrest the increasing pitch-attitude, let alone reverse it.
Quote:
"...knowing how to fly a jet transport airplane using pitch and power in all flight regimes, normal and abnormal, is absolutely, fundamentally paramount in this business, period."
Amen to that. Those of us who have hand-flown jets in the cruise for long periods know only too well that a single degree of pitch represents nearly 1000 ft/min (rather more on Concorde...). Practising it without the luxury of the FD, with or without IAS display, needs at least to be encouraged. That would best include a step-climb at CLB thrust with IAS, and a step-descent.
Lonewolf_50,
I reckon that, as you suggest, the audio signature would have changed considerably as the aircraft slowed down: engine noise gradually becoming more apparent as the air noise diminished. But, whereas subtle changes in sound can attract attention when you are relaxed, I suspect that they might not when the adrenalin is running?
Hi Chris;
Re the longer period - the reduction in indicated altitude lasted about 12 seconds with its lowest point about 2-3 seconds after the loss of speed indication and A/P-A/T disconnection.
So in that sense, even though there was no negative 'g' loading to speak of associated with the indication of height loss, a reaction to correct the loss, about 340' indicated could be construed as reasonable although in my mind unusual.
This pull on the PF's stick occurred within a half-second of the indicated airspeed & altitude loss, reaching 10deg backstick in about 2 seconds, (of 16deg full backstick available or about 65% backstick), then back almost to neutral then 11deg NU again within 6 seconds. The AoA went from about 2deg to 6 about 4 seconds after the loss, and the pitch went from and average of around 2deg to 11deg in the same time period or at a rate of about 1deg/sec with a max 'g' of about 1.5+g. The stall warning blipped at 6deg AoA about 7 seconds after the UAS event.
All this occurred within the first 12 seconds after the initial UAS event.
Those who have flown these aircraft will understand the "inertia" of such a dynamic change in pitch and would know intuitively that it would take some gentle, but quick handling to get the nose back down without significant negative 'g' for those in the back and loss of energy for the airplane.
After the initial twelve seconds, the side stick position varied back and forth but almost all the time within the NU area of stick movement.
Re the longer period - the reduction in indicated altitude lasted about 12 seconds with its lowest point about 2-3 seconds after the loss of speed indication and A/P-A/T disconnection.
So in that sense, even though there was no negative 'g' loading to speak of associated with the indication of height loss, a reaction to correct the loss, about 340' indicated could be construed as reasonable although in my mind unusual.
This pull on the PF's stick occurred within a half-second of the indicated airspeed & altitude loss, reaching 10deg backstick in about 2 seconds, (of 16deg full backstick available or about 65% backstick), then back almost to neutral then 11deg NU again within 6 seconds. The AoA went from about 2deg to 6 about 4 seconds after the loss, and the pitch went from and average of around 2deg to 11deg in the same time period or at a rate of about 1deg/sec with a max 'g' of about 1.5+g. The stall warning blipped at 6deg AoA about 7 seconds after the UAS event.
All this occurred within the first 12 seconds after the initial UAS event.
Those who have flown these aircraft will understand the "inertia" of such a dynamic change in pitch and would know intuitively that it would take some gentle, but quick handling to get the nose back down without significant negative 'g' for those in the back and loss of energy for the airplane.
After the initial twelve seconds, the side stick position varied back and forth but almost all the time within the NU area of stick movement.
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" We have been NU for a while"
If the Captain had been told that this was for over 2 minutes... By then it might well have been too late.
PF might not have known. It is difficult to estimate time PAST. Time from NOW is easier.
("When DID I put the egg in to boil ?" Or "I must take the egg out in 4 minutes time.")
When navigating, one was trained to note the TIME of an observation. ( "Was that fix 30 OR was it 35 minutes ago ?" meant that it was somewhat dubious.)
A change of sounds on the F/D may cause one to look around to try and see that " All is Well"... Nothing noticed ?
(The THS was following the PF's order to go more NU than usual ? Altimeters were moving too rapidly to read ? Was it only possible to NOTICE the "10,000ft" because of the change if the first digit?)
If the Captain had been told that this was for over 2 minutes... By then it might well have been too late.
PF might not have known. It is difficult to estimate time PAST. Time from NOW is easier.
("When DID I put the egg in to boil ?" Or "I must take the egg out in 4 minutes time.")
When navigating, one was trained to note the TIME of an observation. ( "Was that fix 30 OR was it 35 minutes ago ?" meant that it was somewhat dubious.)
A change of sounds on the F/D may cause one to look around to try and see that " All is Well"... Nothing noticed ?
(The THS was following the PF's order to go more NU than usual ? Altimeters were moving too rapidly to read ? Was it only possible to NOTICE the "10,000ft" because of the change if the first digit?)
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Linktrained
Quite possible - analogue instrumentation also uses a different cognitive channel so you can react to visual patterns while reading other numbers. The crew were showing all the signs of cognitive overload: fixation on roll not pitch and flight path. (cognitive tunneling) - disregard of auditory cues - such as the stall warning.
An altimeter needle 'winding down' may have been more of an attention getter for them - and definitely for the captain.
The THS was following the PF's order to go more NU than usual ? Altimeters were moving too rapidly to read ? Was it only possible to NOTICE the "10,000ft" because of the change if the first digit?
An altimeter needle 'winding down' may have been more of an attention getter for them - and definitely for the captain.
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Remember the digits change colour to emphasise abnormal rates...
Is there a QCRH? (Quick Reference Color Handbook)
Just the ticket, additional sensory load....
My intuition from the outset was mechanical issue. After nearly four years, it boils down to a change in TYPE, on the fly....
Interface is a species of Mx... Loss of control by definition happened at the first Stall Warn.... None of the three pilots had a good get on the aircraft after that.
Read the recommendations, and then we can talk about PE.
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Manual trim is not available with G+Y hydraulic failure, only elevator is being held in last position by the integrator it is like trim through the elevator and after gear down even that is not available. THS cannot be moved without G and Y.
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Dozy
And once changed they stay that way. The aircraft was dropping at 11,000fpm or so... An analogue altimeter winding down at that rate would wake up the most tunnel visioned pilot. 
Remember the digits change colour to emphasise abnormal rates..
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Generally if your altimeter digits are in amber, you have an issue that needs correcting. If they're red, then that issue is seriously dangerous. The "tape" display is also an indication of vertical speed.
When we did the sim experiment, the digits were still amber when we began the recovery procedure - but it was very noticeable. Unwinding "steam gauge" style is definitely a secondary indicator that can be more easily picked up than read, but so is the colour change and the "tape" display.
@Lyman - no, the altimeter digit colour and tape display are not dependent on control law.
When we did the sim experiment, the digits were still amber when we began the recovery procedure - but it was very noticeable. Unwinding "steam gauge" style is definitely a secondary indicator that can be more easily picked up than read, but so is the colour change and the "tape" display.
@Lyman - no, the altimeter digit colour and tape display are not dependent on control law.
Last edited by DozyWannabe; 22nd Feb 2013 at 19:15.
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Red button
Crash de l?Airbus Rio-Paris d?Air France: la dernière expertise - Challenges
In english (approximate ..
)
Google*Traduction
Crash de l?Airbus Rio-Paris d?Air France: la dernière expertise - Challenges
In english (approximate ..
)Google*Traduction
Last edited by jcjeant; 22nd Feb 2013 at 22:49.
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Very approximate, I'd say...
We've already covered the ins-and-outs of the "red button" on these threads several times though, so it's not really worth going into it again - because no-one on either side of the argument is likely to change their minds.
Originally Posted by Google Translate
He wants such as Airbus civilians are equipped with a "red button" to allow pilots to resume direct the plane to hand out a purely management computer theft.
We've already covered the ins-and-outs of the "red button" on these threads several times though, so it's not really worth going into it again - because no-one on either side of the argument is likely to change their minds.
Dozy;
As a refresher, the altimeter scale is displayed in white, the digital numbers in green, all against a gray background.
The analog vertical speed needle is green and the scale is white on a gray background. The digital display normally "attaches" itself to the analog needle as shown by the first image.
As shown in the 2nd image, at vertical speeds greater than 6000fpm the analog needle stays at the end of the scale and it is both the digital display and analog needle which turn amber. The digital rate of descent is displayed at the bottom or top of the VS display as appropriate.
In our sim exercise (A330) the analog standby altimeter needle was going around the dial once every 3 seconds...THAT gets one's attention.
As a refresher, the altimeter scale is displayed in white, the digital numbers in green, all against a gray background.
The analog vertical speed needle is green and the scale is white on a gray background. The digital display normally "attaches" itself to the analog needle as shown by the first image.
As shown in the 2nd image, at vertical speeds greater than 6000fpm the analog needle stays at the end of the scale and it is both the digital display and analog needle which turn amber. The digital rate of descent is displayed at the bottom or top of the VS display as appropriate.
In our sim exercise (A330) the analog standby altimeter needle was going around the dial once every 3 seconds...THAT gets one's attention.
Last edited by PJ2; 23rd Feb 2013 at 00:35.