AF447 wreckage found
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Ozone smell probably came from the Cb overshoot they were flying near. I believe the top of the Cb was estimated by Meteo France as 52000 feet, and by Vasquez as 56000 feet. Ozone is present in significant amounts near the tropopause and the Cb overshoot reached into the ITCZ tropopause by 6,000 feet according to Vasquez.
The PNF seems to have recognized what it was.
The PNF seems to have recognized what it was.
Last edited by SaturnV; 31st Jul 2011 at 21:20.
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@ Jando - was the real aircraft airspeed < 60kts or was this an erroneous reading due to icing? It is a pity if it is the case that when airspeed is unreliable, or all 3 ADC disagree or are out of range, the stall warning computer decideds that the aircraft is not in a "real" airborne situation and decides not to play ball when the situation actually may be recoverable.
It would appear the absence and presence of the stall warning may have added to some of the confusion on the flight deck, though on some aircraft and dependent on pilot technique, the stall warning or stick shaker can be activated during recovery from the stall. But maybe these guys had never experienced this and of course its always easier from the armchair.
In system design, probability is regularly used when deciding how safe a system needs to be or how complex the logic should be. It may be that loss of all air data was of a suitably low probability to not be considered in the stall warning inhibit logic. As someone else said earlier maybe this is one of those 1 in 10000000 events.
It would appear the absence and presence of the stall warning may have added to some of the confusion on the flight deck, though on some aircraft and dependent on pilot technique, the stall warning or stick shaker can be activated during recovery from the stall. But maybe these guys had never experienced this and of course its always easier from the armchair.
In system design, probability is regularly used when deciding how safe a system needs to be or how complex the logic should be. It may be that loss of all air data was of a suitably low probability to not be considered in the stall warning inhibit logic. As someone else said earlier maybe this is one of those 1 in 10000000 events.
Originally Posted by EGPFlyer
From my FCOM
"With the sidestick at neutral, wings level, the system maintains 1 g in pitch"
I've never heard of 'pitch hold'
"With the sidestick at neutral, wings level, the system maintains 1 g in pitch"
I've never heard of 'pitch hold'
I've flown 320/19 with MSNs in low 1000s and never spotted the tendency to pitch up while handflying high. As DozyWannabe mentioned: this quirk was ironed out of TA FBW Airbuses. Difference between gravity on the Earth's surface and at FL390 is about 0.4%, between the equator and poles is 0.5%, I don't think that having constant 1G value of 9.81 ms^-1 in your FBW was good idea, if it ever was used. Could be miscalibration of vertical accelerometer and that there are some Airbi that pitch down slowly, instead of up. We'll have to turn Mythbusters' attention to the issue.
Originally Posted by predictorM9
I may be wrong, but if the static pressure system was totally unaffected, why does the vertical speed graph (page 109 of the report, second graph from top) looks so weird, with huge jumps??
Originally Posted by pedrobaltic
was the real aircraft airspeed < 60kts or was this an erroneous reading due to icing?
Originally Posted by pedrobaltic
It is a pity if it is the case that when airspeed is unreliable, or all 3 ADC disagree or are out of range, the stall warning computer decideds that the aircraft is not in a "real" airborne situation and decides not to play ball when the situation actually may be recoverable.
Originally Posted by predictorM9
They failed to identify a stall
Originally Posted by Mac the Knife
So why didn't they look at the attitude indicator/s, which would have shown them to be steeply pitched up?
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Well Airbus manuals would say that wouldn't they.(about pitch attitude & height)
However if you take the guidance out (Autopilot) at 40,000ft on a 332 and wait.. The a/c TENDS to climb. Tried it a few times on different days as was interested after I knocked the disengage button on the side stick button with our ungainly hard plastic tech log.. Noticed the a/c was STARTING a gentle climb.
Whatever, I still believe that an attitude indicated indicating 16 deg NU. At height would look weird to any heavy jet pilot. If that 1.6 g spike is true that probably explains the INITIAL climb.
Again think too much blame pointing at the pilots..(all dead men who can not defend their corner)
However if you take the guidance out (Autopilot) at 40,000ft on a 332 and wait.. The a/c TENDS to climb. Tried it a few times on different days as was interested after I knocked the disengage button on the side stick button with our ungainly hard plastic tech log.. Noticed the a/c was STARTING a gentle climb.
Whatever, I still believe that an attitude indicated indicating 16 deg NU. At height would look weird to any heavy jet pilot. If that 1.6 g spike is true that probably explains the INITIAL climb.
Again think too much blame pointing at the pilots..(all dead men who can not defend their corner)
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Quote:
I had already asked you this earlier, but now that we have a much more detailed record of 447s final minutes maybe you're ready to answer - at which point didn't "the software" give them what they asked for?
Although this question wasn't addressed to me I'm going to answer it.
The question you ask is disingenuous. The complaint is not that the software didn't do what it was supposed to do but that what the software was doing was not communicated to the crew in an intelligible way.
It's simple.
(a) When the airplane is within the flight envelope the stall warning provides an aural communication to the pilots: SILENCE.
(b) when the software decides the airplane is outside established parameters it provide an aural communication to the pilots: STALL STALL STALL
(c) when the software decides that the airplane has so drastically exceeded established parameters that the data should be considered invalid it provides an aural communication to the pilots: SILENCE.
Now, if you think that the pilots were confused and failed to recognize the stall for what it was then you have to ask yourself how the above represents good software design. Because it does not. It's horrible software design. It's horrible software design for the software to communicate the exact same aural message (and silence is an aural message) to the pilots both when things are 100% good and when things have gone totally to hell.
I had already asked you this earlier, but now that we have a much more detailed record of 447s final minutes maybe you're ready to answer - at which point didn't "the software" give them what they asked for?
Although this question wasn't addressed to me I'm going to answer it.
The question you ask is disingenuous. The complaint is not that the software didn't do what it was supposed to do but that what the software was doing was not communicated to the crew in an intelligible way.
It's simple.
(a) When the airplane is within the flight envelope the stall warning provides an aural communication to the pilots: SILENCE.
(b) when the software decides the airplane is outside established parameters it provide an aural communication to the pilots: STALL STALL STALL
(c) when the software decides that the airplane has so drastically exceeded established parameters that the data should be considered invalid it provides an aural communication to the pilots: SILENCE.
Now, if you think that the pilots were confused and failed to recognize the stall for what it was then you have to ask yourself how the above represents good software design. Because it does not. It's horrible software design. It's horrible software design for the software to communicate the exact same aural message (and silence is an aural message) to the pilots both when things are 100% good and when things have gone totally to hell.
The problem here is that, FBW Airbuses are flown differently from conventional airliners. They purely don't give you any feed-back on the side-sticks (and on ATS). And when confronted with a situation of multiple failures, pilots tend to fly by their pants...that is why the PF Co-Pilot voiced his impression about going with a crazy speed.
They were in a turbulent area (no sense of posture), they had no correct speed informations (no complete visual clues) and no feed-back on the side-sticks.
jcjeant shows it all...
The stick of PF busy making mayonnaise ..
The lack of feed-back (and interconnection between) the side-sticks was IMO a major factor, on the inability of the pilots to properly identify the stalling conditions.
One can always argue about the stall stall synthetic voice warning, but we must remember also, the number of gear-up landings that have been made in the past with the horn ON, all the way down to the tarmac...
Now put that voice coming on when you put the nose down and turn that madness situation into an accident...
Yes, the systems behaved exactly as designed.
Yes the situation was poorly handled by the whole crew.
But when we take away from the man/machine interface such an important clue (feed-back) we are forgetting that those aircrafts are ultimately flown by men and that men revert to basics when in face of an outstanding dangerous situation.
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those aircrafts are ultimately flown by men and that men revert to basics when in face of an outstanding dangerous situation.
Computer pilots are handed an unfimiliar situation when the AP drops out (remember Roselawn ?).
With less hands-on training for the "men", what do you expect ?
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(As far as I know the stall warning is inhibited because the AoA vanes do not work below 60 kts. You cannot sound a stall warning when you have no working sensor to detect a stall.)
According to many prior posts here, the Stall Warning shuts off below 60 kt IAS. Why they have IAS input to SW is beyond me. The DC-10, for example, uses only AOA for SW.
Regardless of IAS, the plane was moving through the air fast enough to keep the AOA vane aligned with the relative wind, even as they were falling like a brick.
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@aguadalte - Tactile feedback will come into it, yes - but it's worth remembering that the same thing happened to the Birgenair 757 which had interconnected yokes, and the psychological impact and tragic result was much the same.
@Graybeard - As I said, I suspect that Airbus will be revisiting their logic over this one. However at the same time I think Ranger one was right when he said:
Remember that the stall warning was sounding for 57 seconds before the values went out of usable range and it shut off. How in the hell did that happen?
@Graybeard - As I said, I suspect that Airbus will be revisiting their logic over this one. However at the same time I think Ranger one was right when he said:
Remember that the stall warning was sounding for 57 seconds before the values went out of usable range and it shut off. How in the hell did that happen?
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Remember that the stall warning was sounding for 57 seconds before the values went out of usable range and it shut off. How in the hell did that happen?
Some posts conclude with aspects which tend to ‘blame’ the crew.
I suggest that before coming to any conclusion a wide range of ‘human’ aspects should be considered.
The crew were faced with a sudden failure of an airspeed display: This is not obviously an unreliable airspeed – there is no display; thus, no demanding thought of using an UAS checklist. Remedial action might focus on reinstating the display or using an alternative source.
With all airspeed displays failing, again there is no obvious link to anything being ‘unreliable’. The priority action has to be to fly the aircraft, but without any specific checklist, basic aero / control concepts have to be recalled from memory and used in an aircraft where the control characteristics might not be best suited for a ‘novice’ pilot.
Add a stall warning to this scenario, which initially and logically, might have been disregarded as false: – Technically, an inappropriate association of stall with airspeed, but ‘stall’ is shown on the airspeed scale and everyone talks about stall speed, thus without any speed display why believe a stall (speed) warning. This was a mindset which unfortunately was not reversed later even with a valid warning, but there were no other stronger cues to trigger a change of view, particularly in a rapidly developing and very confusing situation.
These humans – the crew, may not have deduced that the aircraft had actually stalled until very late in the event, if at all.
Why did the aircraft climb: The loss of airspeed affects the ADC in a way in which the indicated altitude suddenly reads low (see FDR and previous events). In this instance, the crew focus on altitude recovery – avoidance of an altitude bust – they are ‘the juniors’ responsible to the absent captain and thus have responsibility for a safe and accurate flight. Did they deduce turbulence or another affect of adjacent Cbs. Add this to the developing scenario as above, then apparently inattentive control may not be surprising.
Possibly both crew focused too much of their ‘cognitive resource’ on deducing the ‘technical’ situation and problem solving, flying the aircraft was no longer #1 priority. This might not have been a result of a conscious choice, but due to the surprise and confusion of an unfolding complex event in a timescale incompatible with an ability to think, understand, and act.
I suggest that before coming to any conclusion a wide range of ‘human’ aspects should be considered.
The crew were faced with a sudden failure of an airspeed display: This is not obviously an unreliable airspeed – there is no display; thus, no demanding thought of using an UAS checklist. Remedial action might focus on reinstating the display or using an alternative source.
With all airspeed displays failing, again there is no obvious link to anything being ‘unreliable’. The priority action has to be to fly the aircraft, but without any specific checklist, basic aero / control concepts have to be recalled from memory and used in an aircraft where the control characteristics might not be best suited for a ‘novice’ pilot.
Add a stall warning to this scenario, which initially and logically, might have been disregarded as false: – Technically, an inappropriate association of stall with airspeed, but ‘stall’ is shown on the airspeed scale and everyone talks about stall speed, thus without any speed display why believe a stall (speed) warning. This was a mindset which unfortunately was not reversed later even with a valid warning, but there were no other stronger cues to trigger a change of view, particularly in a rapidly developing and very confusing situation.
These humans – the crew, may not have deduced that the aircraft had actually stalled until very late in the event, if at all.
Why did the aircraft climb: The loss of airspeed affects the ADC in a way in which the indicated altitude suddenly reads low (see FDR and previous events). In this instance, the crew focus on altitude recovery – avoidance of an altitude bust – they are ‘the juniors’ responsible to the absent captain and thus have responsibility for a safe and accurate flight. Did they deduce turbulence or another affect of adjacent Cbs. Add this to the developing scenario as above, then apparently inattentive control may not be surprising.
Possibly both crew focused too much of their ‘cognitive resource’ on deducing the ‘technical’ situation and problem solving, flying the aircraft was no longer #1 priority. This might not have been a result of a conscious choice, but due to the surprise and confusion of an unfolding complex event in a timescale incompatible with an ability to think, understand, and act.
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IMHO, and FWIW, I lay the blame for the crash into the sea on the shoulders of the pilot, for not doing the correct stall recovery drill, i.e. unload or drop the nose to recover the airspeed and at 30'000 ft, hang the altitude loss. The fact that the aircraft was descending rapidly is not a valid reason to pull back on the side stick.
The reason for the stall I lay squarely on the shoulders of Airbus/Air France for not fixing the pitot problem years earlier.
The reason for the stall I lay squarely on the shoulders of Airbus/Air France for not fixing the pitot problem years earlier.
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"According to many prior posts here, the Stall Warning shuts off below 60 kt IAS. Why they have IAS input to SW is beyond me. The DC-10, for example, uses only AOA for SW.
Regardless of IAS, the plane was moving through the air fast enough to keep the AOA vane aligned with the relative wind, even as they were falling like a brick."
I completely agree. As long as the plane is in the air there is always 60 kts of relative wind, even if the angle of attack is so high that the pitot measure wrong speeds. The fact that they certified the logic behind this is for me a huge mistake. As long as the AOA is not insane it doesn't matter. But if the aircraft is capable of 45 degrees AOA, they should do a logic that also works in this case (irrespective of the issue of displaying the AOA info to pilots).
Also, what matters is not the fact that it sounded for 57 seconds straight. What matters is the fact that pilots push the stick forward and then the stall warning sound. If you were piloting this plane with all the other faulty sensors, wouldn't you start to think that the stall warning is faulty too?
This kind of behavior of the stall warning is only caused by the faulty logic, and the BEA does not seem to want to address this...
Regardless of IAS, the plane was moving through the air fast enough to keep the AOA vane aligned with the relative wind, even as they were falling like a brick."
I completely agree. As long as the plane is in the air there is always 60 kts of relative wind, even if the angle of attack is so high that the pitot measure wrong speeds. The fact that they certified the logic behind this is for me a huge mistake. As long as the AOA is not insane it doesn't matter. But if the aircraft is capable of 45 degrees AOA, they should do a logic that also works in this case (irrespective of the issue of displaying the AOA info to pilots).
Also, what matters is not the fact that it sounded for 57 seconds straight. What matters is the fact that pilots push the stick forward and then the stall warning sound. If you were piloting this plane with all the other faulty sensors, wouldn't you start to think that the stall warning is faulty too?
This kind of behavior of the stall warning is only caused by the faulty logic, and the BEA does not seem to want to address this...
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It was real. Pitot 1 unblocks at 2:10:35, pitot 3 at 2:11:08. After that they agree until AoA goes above 30° and everything becomes mess.
So the AOA data shouldn't have been "rejected" at all. The system worked as designed, as stressed by the BEA. But the design on this point is bad, and adds unnecessary confusion during emergencies.
I don't see why we should blame the pilots for discarding a warning system that is behaving erratically and against your intuition (nose up= stall, nose down=no stall).
Agreed it sounded 54 seconds straight and they should have done something way earlier. But they were about to fix the stall problem multiple times, when they pushed the stick forward (and the stall warning sounded again at that time... preventing them from continuing in this direction).
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damning report
Having read report 3 and the CVR transcript I am no longer surprised by the ineptness of the handling crew and the crash, more so the fact that they actually managed to get the plane airborne in the first place.
they overlooked just about every lesson that one learns within the first few hours of primary training, simply a horrific testament to modern training and modern electronically flown a/c where manual flying is not so much a requrement but actually discouraged. I hope the whole flying community learns from this crash.
they overlooked just about every lesson that one learns within the first few hours of primary training, simply a horrific testament to modern training and modern electronically flown a/c where manual flying is not so much a requrement but actually discouraged. I hope the whole flying community learns from this crash.
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what faulty logic? the only faulty logic was the pf who looked at the vsi which was pinned to the bottom, and he couldnt deduce that they were fully stalled out. a very elementary mistake