AF447 wreckage found
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nitpicker330 - I guess you must be right otherwise the flight data recorder wouldn't have recorded it ... so they spent 3 minutes pitched up with the throttles closed and the altimeter plunging waiting for the speed to come back down ... what did they think was happening? 
In all the documented incidents so far there has never been an issue with the Inertial Attitude displayed on the primary flight displays or on the separate standby. A simple cross check of all 3 would confirm the same.
Airspeed issues and associated overspeed or underspeed ( or indeed both ) warnings were what happened requiring the crew to look "through" their displays and revert to "basic flying skills"
Oh, and no modern western built transport has an AOA indicator fitted.
Who knows what this crew were thinking, who knows how fatigued they were on the night? Who knows how much Turbulence they were dealing with?
All things being equal they "should" have been able to deal with the situation, obviously all things weren't equal.
Airspeed issues and associated overspeed or underspeed ( or indeed both ) warnings were what happened requiring the crew to look "through" their displays and revert to "basic flying skills"
Oh, and no modern western built transport has an AOA indicator fitted.
Who knows what this crew were thinking, who knows how fatigued they were on the night? Who knows how much Turbulence they were dealing with?
All things being equal they "should" have been able to deal with the situation, obviously all things weren't equal.
Last edited by nitpicker330; 28th May 2011 at 13:29.
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nojwod
Is there any explanation/reason for the two momentary roll inputs by the PF?
Could these indicate a deliberate check by the PF as in, 'Am I really connected to the control surfaces?'
....... indicate that something either in the instrumentation or the plane's response to inputs was diametrically opposed to what the crew expected to see or experience.
Could these indicate a deliberate check by the PF as in, 'Am I really connected to the control surfaces?'
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my comments as a PPL/IMC holder:
If I know that Power plus attitude=performance, so did all 3 pilots there that night. They had power (the engines were working normally) they had attitude info (attitude indicator, not derived from pitots) so obtaining a performance seems the logical way to go. The time the descent took rules out the startle factor, and as is well known, once the descent stabilises at 1g, the seat of the pants feel is useless at best and misleading at worst, yet they still should have had the AI. Again, even as a PPL I know to trust my instruments and ignore the seat of pants sensations. So, why didn't they??
I can see a couple of possibilities- 1. they didn't trust the AI as they were aware of the pitot problems and decided to go with the seat of pants sensations or 2. the stall they found themselves in was irrecoverable due to some design problem or issue inherent in the jets design. No comment whatsoever on AB vs boeing, but don't swept wing jets has a nasty characteristic of entering a flat stall which is hard/very hard to break?
Given the possibility of option 2, and if I were AF or AB I would be looking to promote option (1) since option (2) has the unpalatable effect of admitting that some stalls are invariably fatal, not something which passengers want to hear. So much cleaner to blame it on human error, psychologically, its easier on passengers to believe that the pilots made a mistake, rather than face the possibility that a particular set of circumstances will result in an invariably fatal outcome. What do the stable extroverts amongst us think?
If I know that Power plus attitude=performance, so did all 3 pilots there that night. They had power (the engines were working normally) they had attitude info (attitude indicator, not derived from pitots) so obtaining a performance seems the logical way to go. The time the descent took rules out the startle factor, and as is well known, once the descent stabilises at 1g, the seat of the pants feel is useless at best and misleading at worst, yet they still should have had the AI. Again, even as a PPL I know to trust my instruments and ignore the seat of pants sensations. So, why didn't they??
I can see a couple of possibilities- 1. they didn't trust the AI as they were aware of the pitot problems and decided to go with the seat of pants sensations or 2. the stall they found themselves in was irrecoverable due to some design problem or issue inherent in the jets design. No comment whatsoever on AB vs boeing, but don't swept wing jets has a nasty characteristic of entering a flat stall which is hard/very hard to break?
Given the possibility of option 2, and if I were AF or AB I would be looking to promote option (1) since option (2) has the unpalatable effect of admitting that some stalls are invariably fatal, not something which passengers want to hear. So much cleaner to blame it on human error, psychologically, its easier on passengers to believe that the pilots made a mistake, rather than face the possibility that a particular set of circumstances will result in an invariably fatal outcome. What do the stable extroverts amongst us think?
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Nitpicker330, (post 700) sorry but I have to call you on that statement. Many Boeing 777's and 737NG's have AOA indicators displayed in the upper right corner of the PFD. Delta Air Lines and American Airlines started this trend back around 2001. It is a Boeing option, you just have to tick the box when you order the airplane and they will deliver the AOA. I believe it's standard on the 787.
Last edited by Spooky 2; 28th May 2011 at 13:24. Reason: new information
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Why did the autopilot then auto-thrust disengaged ?
"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall "
At this time, it seems that there were no Pitot problem ?
Why did the autopilot then auto-thrust disengaged ?
At this time, it seems that there were no Pitot problem ?
Why did the autopilot then auto-thrust disengaged ?
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Similar erroneous AOA indication experience on B767300
A couple years ago, I had to fly between two mounstrous squall lines (30nm appart) on a B767300ER. I was descending thru FL250 in dusty air (no water content) for an approach into Lahore, Pakistan, when the stick shaker was triggered continuously for about 1 minute with severe turbulence. I was on FLCH, thrust idle and the airplane was climbing at 500fpm for the whole minute. The AI was showing about -5 to 0 degree. Until today, I assume I encountered the mother of all updraft and for that reason, a high angle of attack information was sensed and triggered the stall warning system.
I was then transferred to the Airbus fleet and prayed everyday I wouldn't encountered the same scenario aboard the A320 I was flying because I had no clue how it would behave in such a situation. I am sure it would be way more confusing than how it happened in the 76 due to the relative complexity of the flight envelope protection system.
This is not an Airbus bashing post but a personal experience that may help understand what happened in AF447.
If it ain't Boeing I'll be going but not by choice...
I was then transferred to the Airbus fleet and prayed everyday I wouldn't encountered the same scenario aboard the A320 I was flying because I had no clue how it would behave in such a situation. I am sure it would be way more confusing than how it happened in the 76 due to the relative complexity of the flight envelope protection system.
This is not an Airbus bashing post but a personal experience that may help understand what happened in AF447.
If it ain't Boeing I'll be going but not by choice...
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OAT
Is any OAT information available? I am recalling the Pulkovo 612 accident, that beside a daredevil decision by the Captain to overclimb CB also was hit by a monstrous updraft sending the plane into a 16,000 fpm zoom to FL420, where it stalled.
"Pulkovo 612 departed Anapa (AAQ) for St. Petersburg (LED). The Tupolev climbed to the cruise altitude of 35,100 feet (10.700 m). Because of storm cells ahead, the pilot decided to change course laterally by 20 km and attempted to climb over the storm cells. However, the thunderstorm front was unusually high, extending up to 15 km (49,000 feet). The Tu-154 entered an area of severe turbulence, pushing up the airplane from 11.961 m to 12.794 m within just 10 seconds. The angle of attack increased to 46 degrees and the airspeed dropped to zero."
Very little is being said in this thread about highly unusual and unexpected WX phenomena that may have caused the rapid freezing of the pitots and the initial upset. Could sudden changes in OAT those minutes into the flight give a hint?
Pardon me for entering ID badge area with my RTF and ICAO 5 English rating.
"Pulkovo 612 departed Anapa (AAQ) for St. Petersburg (LED). The Tupolev climbed to the cruise altitude of 35,100 feet (10.700 m). Because of storm cells ahead, the pilot decided to change course laterally by 20 km and attempted to climb over the storm cells. However, the thunderstorm front was unusually high, extending up to 15 km (49,000 feet). The Tu-154 entered an area of severe turbulence, pushing up the airplane from 11.961 m to 12.794 m within just 10 seconds. The angle of attack increased to 46 degrees and the airspeed dropped to zero."
Very little is being said in this thread about highly unusual and unexpected WX phenomena that may have caused the rapid freezing of the pitots and the initial upset. Could sudden changes in OAT those minutes into the flight give a hint?
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Auto trim is disabled in Alternate law
I too am gobsmacked, that in this day and age Airbus have managed to design another generation of machine that doesn't do what you could reasonably& logically expect.
That's not how the system works. Yipoyan is confusing an autopilot trimming against a pilot induced control input with the normal FBW response. If the crew here had pushed on the stick with sufficient authority, at any speed, the trim would move nose down to match that response.
This still doesn’t address why the trim was moved to the 13 degree nose up position.
The QRH spells the situation quite clearly:---
Unreliable speed indic/ADR check proc:-
Maybe due to Radome damage, air probe failure or obstruction
Indicated Alt may be effected if static probes effected
Unreliable airspeed cannot be detected by the ADIRU
Since Flight control laws maybe effected maneuver with care
Unreliable speed may be suspected by-
--- Speed discrepancies between ADR 1, 2, 3 and standby
---Fluctuating or unexpected increase/decrease/steady indicated speed or pressure altitude
---ABNORMAL CORRELATION OF THE BASIC FLIGHT PARAMETERS
---Abnormal AP/FD/ATHR behavior
---Stall warnings, or overspeed warning or flap relief warnings that contradicts with at least one of the indicated speeds
-RELY ON THE STALL WARNING THAT COULD BE TRIGGERED IN ALTERNATE OR DIRECT LAW. IT IS NOT EFFECTED BY UNRELIABLE AIRSPEEDS BECAUSE IT IS BASED ON AOA
-DEPENDING ON THE FAILURE, THE OVERSPEED WARNING MAY BE FALSE OR JUSTIFIED. BUFFET ASSOCIATED WITH THE OVERSPEED VFE WARNING IS A SYMPTOM OF A REAL OVERSPEED CONDITION.
---Inconsistencies between radio altitude and pressure altitude
---Reduction in aerodynamic noise with increasing airspeed or increase in aerodynamic noise with decreasing speed
*my capitals to emphasize some sections*
Unreliable speed indic/ADR check proc:-
Maybe due to Radome damage, air probe failure or obstruction
Indicated Alt may be effected if static probes effected
Unreliable airspeed cannot be detected by the ADIRU
Since Flight control laws maybe effected maneuver with care
Unreliable speed may be suspected by-
--- Speed discrepancies between ADR 1, 2, 3 and standby
---Fluctuating or unexpected increase/decrease/steady indicated speed or pressure altitude
---ABNORMAL CORRELATION OF THE BASIC FLIGHT PARAMETERS
---Abnormal AP/FD/ATHR behavior
---Stall warnings, or overspeed warning or flap relief warnings that contradicts with at least one of the indicated speeds
-RELY ON THE STALL WARNING THAT COULD BE TRIGGERED IN ALTERNATE OR DIRECT LAW. IT IS NOT EFFECTED BY UNRELIABLE AIRSPEEDS BECAUSE IT IS BASED ON AOA
-DEPENDING ON THE FAILURE, THE OVERSPEED WARNING MAY BE FALSE OR JUSTIFIED. BUFFET ASSOCIATED WITH THE OVERSPEED VFE WARNING IS A SYMPTOM OF A REAL OVERSPEED CONDITION.
---Inconsistencies between radio altitude and pressure altitude
---Reduction in aerodynamic noise with increasing airspeed or increase in aerodynamic noise with decreasing speed
*my capitals to emphasize some sections*
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From the Grauniad. Surely there would be multiple pitots. Could there be a software problem in "voting" in event of discrepancies??
A pilot's analysis
You look at this as an A330 pilot and it's a case of there but for the grace of God. The first sign of trouble was the expectation of turbulence voiced by the first officer. He reduced the speed in anticipation to Mach 0.82, which is normal, and warned the crew. Shortly after entering the turbulence and associated ice, the autopilot disengaged and the first officer commented that the flight control computers had disconnected. This happened because the computers were no longer receiving speed information and neither were the pilots.
I cannot speculate why the pilot climbed the aircraft but it could have been due to confusion caused by the turbulence and sudden instrument failure. The controls at very high altitude are very sensitive and there is only a very small speed envelope, often called "coffin corner", where only a few knots of speed up or down can cause a stall.
So you are flying in this little window of a flight envelope which is perfectly normal and, indeed, you do it every day. But if you are suddenly handed control of an aircraft you can breathe on that little stick and the aircraft can go down one degree. In a very short space of time lost speed and stalled, causing it to fall from the sky. Despite what the pilots must have been going through in the cockpit, the pitch attitude remained fairly constant throughout so the passengers would not have sensed something was seriously wrong. They would have felt mild buffeting of the stalled airflow over the wings and the initial sinking feeling. That's all.
I feel a lot of empathy for the pilots. One could imagine suddenly suffering a total loss of airspeed indication in turbulence in the middle of the night and with all the autopilot systems suddenly failing. The indications, both visual and aural, would have been very confusing. The question for me is why did the instruments that are triple redundant, which means that there are three back-ups, all fail together?
Anonymous A330 pilot
A pilot's analysis
You look at this as an A330 pilot and it's a case of there but for the grace of God. The first sign of trouble was the expectation of turbulence voiced by the first officer. He reduced the speed in anticipation to Mach 0.82, which is normal, and warned the crew. Shortly after entering the turbulence and associated ice, the autopilot disengaged and the first officer commented that the flight control computers had disconnected. This happened because the computers were no longer receiving speed information and neither were the pilots.
I cannot speculate why the pilot climbed the aircraft but it could have been due to confusion caused by the turbulence and sudden instrument failure. The controls at very high altitude are very sensitive and there is only a very small speed envelope, often called "coffin corner", where only a few knots of speed up or down can cause a stall.
So you are flying in this little window of a flight envelope which is perfectly normal and, indeed, you do it every day. But if you are suddenly handed control of an aircraft you can breathe on that little stick and the aircraft can go down one degree. In a very short space of time lost speed and stalled, causing it to fall from the sky. Despite what the pilots must have been going through in the cockpit, the pitch attitude remained fairly constant throughout so the passengers would not have sensed something was seriously wrong. They would have felt mild buffeting of the stalled airflow over the wings and the initial sinking feeling. That's all.
I feel a lot of empathy for the pilots. One could imagine suddenly suffering a total loss of airspeed indication in turbulence in the middle of the night and with all the autopilot systems suddenly failing. The indications, both visual and aural, would have been very confusing. The question for me is why did the instruments that are triple redundant, which means that there are three back-ups, all fail together?
Anonymous A330 pilot
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Repeat after me
Every mother or wife of a pilot should say every day to her son/husband :
"repeat after me one hundred times : when I hear a stall warning I nose down..."
There is absolutely no reason why the PF :
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. "
This is unbelevable exept if you want to suicide.
"repeat after me one hundred times : when I hear a stall warning I nose down..."
There is absolutely no reason why the PF :
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. "
This is unbelevable exept if you want to suicide.
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Hi,
The dinosaurs must think I'm sure the good old days when you had to put the feet on the dashboard for manoeuver elevators to get out of a dive
In the case of FBW aircraft (Airbus particulary) .. may have the same maneuver with two fingers without any effort.
It certainly does not help to understand what is the force exerted on the moving parts
The dinosaurs must think I'm sure the good old days when you had to put the feet on the dashboard for manoeuver elevators to get out of a dive
In the case of FBW aircraft (Airbus particulary) .. may have the same maneuver with two fingers without any effort.
It certainly does not help to understand what is the force exerted on the moving parts
HKPAX:-- Please read my post above. Or better still read the actual QRH you have.
All or 2 of the Pitot probes iced up ( basically failed ) and "confused the system" Overspeed/Under speed warnings resulted, Alt Law, AP A/THR dropped out ......etc etc....
It would have all cleared up after they exited the cloud........
Airbus and Boeing have addressed this issue of super cooled water drops and directed that improved pitot probes be fitted.
All or 2 of the Pitot probes iced up ( basically failed ) and "confused the system" Overspeed/Under speed warnings resulted, Alt Law, AP A/THR dropped out ......etc etc....
It would have all cleared up after they exited the cloud........
Airbus and Boeing have addressed this issue of super cooled water drops and directed that improved pitot probes be fitted.
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Altitude and lateral movement
Would anyone like to comment on this:-
The aircraft is telling the pilots (probably correctly) that they are at 10,000ft. The quoted text implies that the pilots believe this. What mechanism (stall/dive/something else) do they believe has got them from FL350 before any problem arose to FD100 (I know they ended up at one point at FL380 but we don't know that they knew that)?
What manoeuvre are the pilots trying to make on the sidesticks and is there any reason why both of them would be making simultaneous inputs other than that they do not trust one or both of the controls to react to the input?
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred". About fifteen seconds
later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go
ahead you have the controls".
later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go
ahead you have the controls".
What manoeuvre are the pilots trying to make on the sidesticks and is there any reason why both of them would be making simultaneous inputs other than that they do not trust one or both of the controls to react to the input?
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AF Atlantic
Gentlemen & Ladies of course,
Having watched the story since the beginning, I think it is time a few salient points should be pointed out. I think I am qualified to comment having spend 5000 hours as P1 on 330's although I am now retired. I would therefore be happy to accept any corrections.
As I recall from the original ACARS transcripts, all pitot statics were iced up.
The effect of this disconnects the A/P and A/T without pilot input. The airspeed on both PFD's and STBY ASI would be useless and in total conflict to each other. 2 warnings follow, STALL STALL STALL(verbal) followed by immediately by the OVERSPEED warning (I think it is the "Cavalry Charge" bell).
Any sidestick input at this point would be extremely fraught (remember the autopilot is now off).
So, which one do you believe. It seems like the crew were trying to recover from an overspeed event and ended up stalling (throttles closed, pitched up).
The early analysis of the wx showed the flt to be transiting the ITCZ. I spent more hours transiting the Asian one to know that it is not to be taken lightly.
The question then begs-
was the crew aware of the weather approaching;
was the weather radar operating; was it being operated correctly- was the gain on/off, was the tilt down. The radar only shows water droplets not ice, so if it is level or up, nothing shows up at the temperatures one would be experiencing. As I always said to my trainees-: "you have to look at the bottom(of the CB) to understand what the tops might be like".
Given that I have not seen a full report I wont make further comment accept to say especially in the A320/330/340/380 family if in doubt of the warnings, physically sit on your hands until the conflict in your mind is resolved then maybe touch the sidestick.
Having watched the story since the beginning, I think it is time a few salient points should be pointed out. I think I am qualified to comment having spend 5000 hours as P1 on 330's although I am now retired. I would therefore be happy to accept any corrections.
As I recall from the original ACARS transcripts, all pitot statics were iced up.
The effect of this disconnects the A/P and A/T without pilot input. The airspeed on both PFD's and STBY ASI would be useless and in total conflict to each other. 2 warnings follow, STALL STALL STALL(verbal) followed by immediately by the OVERSPEED warning (I think it is the "Cavalry Charge" bell).
Any sidestick input at this point would be extremely fraught (remember the autopilot is now off).
So, which one do you believe. It seems like the crew were trying to recover from an overspeed event and ended up stalling (throttles closed, pitched up).
The early analysis of the wx showed the flt to be transiting the ITCZ. I spent more hours transiting the Asian one to know that it is not to be taken lightly.
The question then begs-
was the crew aware of the weather approaching;
was the weather radar operating; was it being operated correctly- was the gain on/off, was the tilt down. The radar only shows water droplets not ice, so if it is level or up, nothing shows up at the temperatures one would be experiencing. As I always said to my trainees-: "you have to look at the bottom(of the CB) to understand what the tops might be like".
Given that I have not seen a full report I wont make further comment accept to say especially in the A320/330/340/380 family if in doubt of the warnings, physically sit on your hands until the conflict in your mind is resolved then maybe touch the sidestick.
Below the Glidepath - not correcting
Whereas it's a great theory for the press and Airbus that 3 experienced aircrew all forgot the basics of how to fly an aircraft simultaneously, it is of course horse manure. This is just another example of Cognitive Dissonance
When the aircraft started departing from the indicated pitch and speed, the crew were forced to use their experience do determine what was really happening. When some things didn't fit that model, the model was likely changed to accommodate that. Everybody mistrusts a computer, but air instruments are supposed to remain reliable. When an air data computer is driven from air instruments and then to the AP, the symptoms of failure now become complex and less intuitive.
Pitch and thrust control will generally keep you alive, but at night, in a storm, with a cacophony of alerts and warnings going off and the AP trying to fix a problem that didn't exist, somehow the standby AI and thrust settings were not recognized as being the only control references that could be safely relied upon.
Any one of these crew could have probably executed a flawless stall recovery if they had recognized what was happening, but at the given flight level it appears the aircraft rapidly got away from them. So once again the history of aviation safety has an example of a relatively benign event - in this case the failure of the pitot heaters - conspiring with other circumstances to build a scenario that proved fatal for everyone involved.
The fact that the pitot failure was a known condition simply adds to the sorry tale of tombstone engineering practices conducted by the OEMs.
When two simultaneously held cognitions are inconsistent, this will produce a state of cognitive dissonance. Because the experience of dissonance is unpleasant, the person will strive to reduce it by changing their beliefs. Sewell (2006)
Pitch and thrust control will generally keep you alive, but at night, in a storm, with a cacophony of alerts and warnings going off and the AP trying to fix a problem that didn't exist, somehow the standby AI and thrust settings were not recognized as being the only control references that could be safely relied upon.
Any one of these crew could have probably executed a flawless stall recovery if they had recognized what was happening, but at the given flight level it appears the aircraft rapidly got away from them. So once again the history of aviation safety has an example of a relatively benign event - in this case the failure of the pitot heaters - conspiring with other circumstances to build a scenario that proved fatal for everyone involved.
The fact that the pitot failure was a known condition simply adds to the sorry tale of tombstone engineering practices conducted by the OEMs.