AF447 wreckage found
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RWA,
I don't know you're experience but you are one of few posters here asking the right questions.
In the Perpignan Accident the autopilot was disconnected in level flight and the aeroplane decelerated. The pilot would require to applying increasing nose up attitude to maintain level flight. The auto-trim would react correspondingly.
I see your point about the pitch down inputs made by the Air France F/O. I personally believe that these were token gestures to reduce the rate of climb. If the aeroplane has reached a pitch attitude of 10 degrees nose up then the trim would be wound back. The fact that the trim wound all the way back does, in my opinion imply that the F/O's inputs were predominately nose-up and as I say his inputs would have to be sufficient to allow this to happen. I don't think for one second that the THS acted alone or there was a failure.
I completely agree and a very valid point. I believe that in both accidents both crews failed to appreciate that auto-trim was no longer available and it was necessary for them to move the trim wheel.
In my opinion and from all that I have read, the aeroplane responded as it was designed to do in accordance with the pilot inputs that were made.
Why he made those inputs are yet to be explained.
I don't know you're experience but you are one of few posters here asking the right questions.
In the Perpignan Accident the autopilot was disconnected in level flight and the aeroplane decelerated. The pilot would require to applying increasing nose up attitude to maintain level flight. The auto-trim would react correspondingly.
I see your point about the pitch down inputs made by the Air France F/O. I personally believe that these were token gestures to reduce the rate of climb. If the aeroplane has reached a pitch attitude of 10 degrees nose up then the trim would be wound back. The fact that the trim wound all the way back does, in my opinion imply that the F/O's inputs were predominately nose-up and as I say his inputs would have to be sufficient to allow this to happen. I don't think for one second that the THS acted alone or there was a failure.
What it would have amounted to, in aviation terms, is that the 'systems' should have reverted to neutral settings after they signed off - so that the autotrim, for example, would not have just signed off and left the THS at an unheard-of 13 degrees up or so, but would have reduced the angle to a conventional setting (say 3 degrees up or so).
In my opinion and from all that I have read, the aeroplane responded as it was designed to do in accordance with the pilot inputs that were made.
Why he made those inputs are yet to be explained.
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RWA
Agree with your post as well as Man Flex; Have discussed the THS with a few colleagues & I don't see what benefit there is in allowing the THS to remain in a position (that would most likely render the aircraft unflyable) without manual re-trim following reversion to alternate law.
Indeed, (and without knowing the typical range of THS movement during the cruise phase of flight), I can't see why the autotrimming isn't limited to a degree or two beyond the "normal" cruise range, with a warning that it is reaching the limits of its "normal" travel. I doubt that more extreme manoeuvres such as TCAS RA or Terrain avoidance would be hindered significantly by such a limit.
Agree with your post as well as Man Flex; Have discussed the THS with a few colleagues & I don't see what benefit there is in allowing the THS to remain in a position (that would most likely render the aircraft unflyable) without manual re-trim following reversion to alternate law.
Indeed, (and without knowing the typical range of THS movement during the cruise phase of flight), I can't see why the autotrimming isn't limited to a degree or two beyond the "normal" cruise range, with a warning that it is reaching the limits of its "normal" travel. I doubt that more extreme manoeuvres such as TCAS RA or Terrain avoidance would be hindered significantly by such a limit.
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Some of the descriptions of Airbus's propensity to stall are inaccurate and, in my opinion, incorrect.
***************************
330 testflight in Toulouse stalled due to pilot mishandling leading to an unrecoverable stall. Two experienced pilots. Still some debate if the aircraft would have been able to save, still debates about the electronics/protections handling.
320 Perpignan stalled due to THS behavior. Normal pilots. Still some debate about the recovery possibility or not.
Qantas Perth. Aircraft apparently didn't obey pilot orders, recovery succeeded. Still debating about the real reason of the electronic/protections behavior.
**************************
I recently reviewed flight test accidents in FBW airplanes.
The circumstances in the A330 in Toulouuse was caused by deviating from the desired entry conditions and engaging the autopilot with full thrust then shutting one down. Unfortunately during the brief interval between A/P engagement and engine shutdown the autopilot entered altitude capture mode because the selected altitude had been left too low. Because of the nature of altitude capture, the airplane tried to maintain too steep a climb gradient. Some of the envelope protections were not available in altitude capture.
The A320 in Peripignan had two alpha probes frozen effectively outvoting the third (correct) probe. The test card was to verify alpha protection. Clearly with two indications at low values, alpha protection mode was never going to activate. Nevertheless, the crew continued down to the stall to see if it would finally activate (it didn't). During the stall, airflow differences between the various probes cause a transition to direct law. Unfortunately the test was flown at much too low an altitude for recovery.
This paper was presented at the Flight Test Safety Workshop last month.
The A-330 north of Perth is one of the very few in-service, civil flight by wire accidents (several serious injuries). In my opinion, this was a result of a poor voting scheme for a failed sensor. I say "In my opinion" as the formal report has not been released yet.
This was discussed in a 2009 paper at the International Society of Air Safety Investigators. At that time, only three FBW-caused accidents had been reported with no fatalities. AF-447 was not included because the cause wasn't known (and actually still isn't)
I think we should wait for the report to come out. After all, they've only had the flight and cockpit voice recorder data for a few weeks now.
Goldfish
***************************
330 testflight in Toulouse stalled due to pilot mishandling leading to an unrecoverable stall. Two experienced pilots. Still some debate if the aircraft would have been able to save, still debates about the electronics/protections handling.
320 Perpignan stalled due to THS behavior. Normal pilots. Still some debate about the recovery possibility or not.
Qantas Perth. Aircraft apparently didn't obey pilot orders, recovery succeeded. Still debating about the real reason of the electronic/protections behavior.
**************************
I recently reviewed flight test accidents in FBW airplanes.
The circumstances in the A330 in Toulouuse was caused by deviating from the desired entry conditions and engaging the autopilot with full thrust then shutting one down. Unfortunately during the brief interval between A/P engagement and engine shutdown the autopilot entered altitude capture mode because the selected altitude had been left too low. Because of the nature of altitude capture, the airplane tried to maintain too steep a climb gradient. Some of the envelope protections were not available in altitude capture.
The A320 in Peripignan had two alpha probes frozen effectively outvoting the third (correct) probe. The test card was to verify alpha protection. Clearly with two indications at low values, alpha protection mode was never going to activate. Nevertheless, the crew continued down to the stall to see if it would finally activate (it didn't). During the stall, airflow differences between the various probes cause a transition to direct law. Unfortunately the test was flown at much too low an altitude for recovery.
This paper was presented at the Flight Test Safety Workshop last month.
The A-330 north of Perth is one of the very few in-service, civil flight by wire accidents (several serious injuries). In my opinion, this was a result of a poor voting scheme for a failed sensor. I say "In my opinion" as the formal report has not been released yet.
This was discussed in a 2009 paper at the International Society of Air Safety Investigators. At that time, only three FBW-caused accidents had been reported with no fatalities. AF-447 was not included because the cause wasn't known (and actually still isn't)
I think we should wait for the report to come out. After all, they've only had the flight and cockpit voice recorder data for a few weeks now.
Goldfish
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Hi,
Goldfish85
From the BEA report Perpignan
Maybe not very very experienced ... but certainly more than those of the AF447
The crew of Toulouse test flight:
Very more experienced ? .. maybe as test pilots ......
Goldfish85
320 Perpignan stalled due to THS behavior. Normal pilots. Still some debate about the recovery possibility or not.
Captain
Flying hours:
• 12,709 flying hours of which 7,038 on type.
• 128 hours in the previous three months, all on type.
• 14 hours in the previous thirty days, all on type.
• No flying hours in the previous 24 hours.
Co-Pilot
Flying hours:
• 11,660 flying hours of which 5,529 on type.
• 192 hours in the previous three months, all on type.
• 18 hours in the previous thirty days, all on type.
• No flying hours in the previous 24 hours.
Flying hours:
• 12,709 flying hours of which 7,038 on type.
• 128 hours in the previous three months, all on type.
• 14 hours in the previous thirty days, all on type.
• No flying hours in the previous 24 hours.
Co-Pilot
Flying hours:
• 11,660 flying hours of which 5,529 on type.
• 192 hours in the previous three months, all on type.
• 18 hours in the previous thirty days, all on type.
• No flying hours in the previous 24 hours.
The crew of Toulouse test flight:
Nicholas Warner, chief test pilot and captain. 7,713 flying hours experience.
Michel Cais co-pilot. 9,558 flying hours experience.
Jean Pierre Petit engineer. 6,225 flying hours experience.
Michel Cais co-pilot. 9,558 flying hours experience.
Jean Pierre Petit engineer. 6,225 flying hours experience.
Last edited by jcjeant; 13th Jun 2011 at 02:19.
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Many thanks for your open-minded approach, Man Flex. It 'spurred me on' to have another read of the Perpignan report which I linked to earlier. I'm afraid that the paragraph immediately preceding the part I quoted does indeed say that the 'systems,' for reasons best known to themselves, did apparently ignore the pilot's nosedown inputs and leave the THS at 'full up':-
Golden Rivit, the same paragraph also largely answers your question. As far as I know (Airbus pilots please amplify) when the systems go into 'direct law' a message appears saying "USE MAN. PITCH TRIM" - I don't know whether there is an aural warning as well. But the BEA report concludes that this could well have been 'masked' by all the other warnings that would have been going off by that time.
Man Flex, have to 'come to the defence' of the AF447 pilot. He did indeed apply nosedown stick and get the aeroplane practically level, at Mach 0.68, and at an AoA of only four degrees (that is, near enough 'normal flight'). I'm afraid that it looks increasingly likely that the AF447 THS, like the Perpignan one, ignored the pilot's 'nosedown inputs,' and stayed at full up. Which could very well have both caused and maintained the stall?
Anyone know more about that 'automatic compensation system' that the Perpignan report mentions?
When the stall warning sounded, the Captain reacted by placing the thrust levers in the TO/GA detent and by pitching the aeroplane down, in accordance with procedures. The nose-down input was not however sufficient for the automatic compensation system to vary the position of the horizontal stabilizer, which had been progressively deflected to the pitch-up stop by this system during the deceleration. The Captain controlled a left roll movement, caused by the stall. The aeroplane’s high angle of attack and the roll movements generated asymmetry, and a speed variation between ADR 1 and 2 appeared. This increasing divergence caused a rejection of the three ADRs by the FAC then the ELAC. The flight control system then passed into direct law. It is likely that the crew did not notice this due to the emergency situation and the aural stall warning that covered the warning of a change of flight control laws. The Air New Zealand pilot, by saying “alpha floor, we’re in manual” likely considered that the alpha floor function had triggered and that in fact the autopilot had disconnected.
Golden Rivit, the same paragraph also largely answers your question. As far as I know (Airbus pilots please amplify) when the systems go into 'direct law' a message appears saying "USE MAN. PITCH TRIM" - I don't know whether there is an aural warning as well. But the BEA report concludes that this could well have been 'masked' by all the other warnings that would have been going off by that time.
Man Flex, have to 'come to the defence' of the AF447 pilot. He did indeed apply nosedown stick and get the aeroplane practically level, at Mach 0.68, and at an AoA of only four degrees (that is, near enough 'normal flight'). I'm afraid that it looks increasingly likely that the AF447 THS, like the Perpignan one, ignored the pilot's 'nosedown inputs,' and stayed at full up. Which could very well have both caused and maintained the stall?
The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees.
Anyone know more about that 'automatic compensation system' that the Perpignan report mentions?
Last edited by RWA; 13th Jun 2011 at 04:24.
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Video Game
Thank you Basil for what I consider to be the best post so far on this topic. I too have flown the 320 and agree with all you say. I will forever state that they should never have entered the CB in the first place given the circumstances (heavy, high, turbulence). I still feel that the radar was not working. So far there has been no conformation that it was. Why else would trained pilots fly through the red area of a CB ? (see the satellite Wx photo). Something that most of you don't know is that Airbus issued a NOTAM reminding pilots not to depart with inop radar if there was reported CBs enroute. This was sent out some time after the 447 crash. Got me thinking !!
I blame the government watchdogs like the FAA, and others like them, for not paying attention to the type of training required on these new computer driven 'planes. There are a number of items we never covered during our training in the sim. With one day of so called "practice" and then a nerve racking check ride that that was full of surprises, I don't see how any pilot gets any benefit from these stupid sim sessions.
Hope we get more info from the two data recorders soon.
Glad to be retired from a crazy industry such as this.
I blame the government watchdogs like the FAA, and others like them, for not paying attention to the type of training required on these new computer driven 'planes. There are a number of items we never covered during our training in the sim. With one day of so called "practice" and then a nerve racking check ride that that was full of surprises, I don't see how any pilot gets any benefit from these stupid sim sessions.
Hope we get more info from the two data recorders soon.
Glad to be retired from a crazy industry such as this.
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With the Captain on a break ...and two f/o's in charge ...what would be the likely seating arrangement ?
I would imagine the less experienced f/o (800 on type) would be in the RHS as PF and the more experienced f/o in the LHS..
However after the proverbial hit the fan there was a change over of PF..and
this would lead to the f/o in the LHS trying to recover it..with no real experience of operating from that seat ?
is this a possible scenario?
I would imagine the less experienced f/o (800 on type) would be in the RHS as PF and the more experienced f/o in the LHS..
However after the proverbial hit the fan there was a change over of PF..and
this would lead to the f/o in the LHS trying to recover it..with no real experience of operating from that seat ?
is this a possible scenario?
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camel
It is my understanding that a typed Pilot must fly in the Seat which he occupies in his regular role, Captain LHS, F/O, RHS, and relief in either. This puts the F/O in the RHS the one whose panel reads are not recorded. In the ITCZ, my guess is that the F/O is PF. Stand to be corrected.
It is my understanding that a typed Pilot must fly in the Seat which he occupies in his regular role, Captain LHS, F/O, RHS, and relief in either. This puts the F/O in the RHS the one whose panel reads are not recorded. In the ITCZ, my guess is that the F/O is PF. Stand to be corrected.
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jcjeant wrote :
From the BEA report Perpignan
Crew maybe not very very experienced ... but certainly more than those of the AF447
.............
The crew of Toulouse test flight:
Very more experienced ? .. maybe as test pilots ......
What a lot of confusion regarding flight hours !
It's hard to admit for a lot in the industry, but flight hours don't have the same value, depending on the background... Even if it doesn't prevent them for having accidents (see Toulouse Airbus crew, also british Trident stall in the 60's, dozens of others...) hours in a flight test environment have thirty (or more ?) time the value of hours in an airline environnment, with nothing happening in cruise, and landings always identical - if not in external conditions, but for sure in performing. Comparing flight hours of both sides is like mixing strawberries with potatoes.
Maybe there will be an understanding of all this after ?
The Perpignan crew was conducting an acceptance flight, and they had no training for that, period. To call them test pilots is totally unappropriate. I know that in the companies (including mine) you have supposed experienced pilots, calling themselves "test pilots" when they just perform "out-of-maintenance" check flights ....
One day airline pilots will have to admit that their hours don't have big value, compared to other backgrounds ... but as flying big jets is supposed to be the pinnacle of careers, its' not going to happen soon, I'm afraid.
So jcjeant .. please document yourself a little bit about flight testing, ask people or read books...
From the BEA report Perpignan
Crew maybe not very very experienced ... but certainly more than those of the AF447
.............
The crew of Toulouse test flight:
Very more experienced ? .. maybe as test pilots ......
What a lot of confusion regarding flight hours !
It's hard to admit for a lot in the industry, but flight hours don't have the same value, depending on the background... Even if it doesn't prevent them for having accidents (see Toulouse Airbus crew, also british Trident stall in the 60's, dozens of others...) hours in a flight test environment have thirty (or more ?) time the value of hours in an airline environnment, with nothing happening in cruise, and landings always identical - if not in external conditions, but for sure in performing. Comparing flight hours of both sides is like mixing strawberries with potatoes.
Maybe there will be an understanding of all this after ?
The Perpignan crew was conducting an acceptance flight, and they had no training for that, period. To call them test pilots is totally unappropriate. I know that in the companies (including mine) you have supposed experienced pilots, calling themselves "test pilots" when they just perform "out-of-maintenance" check flights ....
One day airline pilots will have to admit that their hours don't have big value, compared to other backgrounds ... but as flying big jets is supposed to be the pinnacle of careers, its' not going to happen soon, I'm afraid.
So jcjeant .. please document yourself a little bit about flight testing, ask people or read books...
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Bubbers44 wrote, "I know we are drifting off topic but I don't understand why the pitch for glideslope and power for airspeed is so hard to comprehend. All autopilots work this way. "
Repeating wrong technique isn't going to make it right. I explained why on the previous page.
The comparison here of autopilot to human is wrong, in that an autopilot is designed to make corrections a number of times a second, which makes speed instability a non factor in flying an approach. The aircraft longitudinal time constant is significantly longer, making autopilot control effective, however a human burdened with multiple tasks, is unable to effectively cope, because of our inherent time constant, especially during multi-tasking workload.
Repeating wrong technique isn't going to make it right. I explained why on the previous page.
The comparison here of autopilot to human is wrong, in that an autopilot is designed to make corrections a number of times a second, which makes speed instability a non factor in flying an approach. The aircraft longitudinal time constant is significantly longer, making autopilot control effective, however a human burdened with multiple tasks, is unable to effectively cope, because of our inherent time constant, especially during multi-tasking workload.
Last edited by opherben; 13th Jun 2011 at 06:36.
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RWA wrote,
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document. I say that being myself a government authorized air accident and incident investigator.
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document. I say that being myself a government authorized air accident and incident investigator.
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Bearfoil
yes of course one of the f/o's is PF due to the Capt being on a break...my point being which one of the f/o's and from which seat ....if the more experienced f/o started of as PF in the RHS i find it hard to believe that he would give control to the less experienced other f/o in the lhs ...
however if the less experienced f/o was PF from the RHS then handed over control to the other F/o in the LHS one can envisage the added problems in trying to sort it all out from the LHS..
make sense?
btw i am in no way trying to blame any of the pilots for this disaster.
yes of course one of the f/o's is PF due to the Capt being on a break...my point being which one of the f/o's and from which seat ....if the more experienced f/o started of as PF in the RHS i find it hard to believe that he would give control to the less experienced other f/o in the lhs ...
however if the less experienced f/o was PF from the RHS then handed over control to the other F/o in the LHS one can envisage the added problems in trying to sort it all out from the LHS..
make sense?
btw i am in no way trying to blame any of the pilots for this disaster.
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In our airline normally the relief FO occupies the seat either P1 or P2 vacates. So in this case the P1 seat. It's assumed that the FO who is most 'senior' will become acting PIC.
As for flying roles: Depending on who is PF and PNF those ''roles'' stay with the seat.
eg. the P1 FO can be ''pilot flying and acting PIC''.
Whether this is what you want is another discussion and best left out of this accident.
As for flying roles: Depending on who is PF and PNF those ''roles'' stay with the seat.
eg. the P1 FO can be ''pilot flying and acting PIC''.
Whether this is what you want is another discussion and best left out of this accident.
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I think I'll bow out soon as this thread is far too up and down for me.
The guy flying was in the RHS and was the least experienced of the three. The guy in the LHS was the other F/O who yes, would have little if any flying experience from that side.
RWA,
I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move. Remember (without getting too technical) that Trim is a function of speed. A pitch change at slow speed has a different effect on Trim than at high speed.
For what it's worth. My reading of the 27th May update is as follows...
The autopilot and autothrust disconnect and the aeroplane reverts to alternate law 2 due to an ADR disagree. They are in turbulent conditions and the aeroplane rolls slightly to the right. The F/O who has been only mildly alert until this moment grabs the sidestick and makes a left nose up input. This may have been instinctive or he may have been reacting to what he saw on his PFD (apparent loss of altitude). This pitch input is enough to cause an increase in the nose attitude to 10 degrees and aeroplane starts a climb. Such an input is fairly agressive at altitude and this creates a zoom climb with a rate of climb momentarily reaching 7000'/min. The THS reacts to this significant and sustained input and starts to wind back relieving the "pressure" on the sidestick. He realises that his initial input is aggressive and slightly checks the rate of pitch reducing the rate of climb to 700'/min (is he seeking 10 degrees pitch?).
I am at a loss what happens from here but it would appear that following the second stall warning he applies TOGA and raises the nose still further, the AoA reaches 6 degrees and continues to increase reaching 16 degrees at 38,000'.
When the aeroplane stalls the AoA reaches 40 degrees and the aeroplane enters Abnormal Attitude law where auto trim ceases and the THS remains at it's previous nose-up position.
I don't know after that whether the elevator alone has the authority to pitch the nose down to what was required but I doubt it.
The guy flying was in the RHS and was the least experienced of the three. The guy in the LHS was the other F/O who yes, would have little if any flying experience from that side.
RWA,
I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move. Remember (without getting too technical) that Trim is a function of speed. A pitch change at slow speed has a different effect on Trim than at high speed.
For what it's worth. My reading of the 27th May update is as follows...
The autopilot and autothrust disconnect and the aeroplane reverts to alternate law 2 due to an ADR disagree. They are in turbulent conditions and the aeroplane rolls slightly to the right. The F/O who has been only mildly alert until this moment grabs the sidestick and makes a left nose up input. This may have been instinctive or he may have been reacting to what he saw on his PFD (apparent loss of altitude). This pitch input is enough to cause an increase in the nose attitude to 10 degrees and aeroplane starts a climb. Such an input is fairly agressive at altitude and this creates a zoom climb with a rate of climb momentarily reaching 7000'/min. The THS reacts to this significant and sustained input and starts to wind back relieving the "pressure" on the sidestick. He realises that his initial input is aggressive and slightly checks the rate of pitch reducing the rate of climb to 700'/min (is he seeking 10 degrees pitch?).
I am at a loss what happens from here but it would appear that following the second stall warning he applies TOGA and raises the nose still further, the AoA reaches 6 degrees and continues to increase reaching 16 degrees at 38,000'.
When the aeroplane stalls the AoA reaches 40 degrees and the aeroplane enters Abnormal Attitude law where auto trim ceases and the THS remains at it's previous nose-up position.
I don't know after that whether the elevator alone has the authority to pitch the nose down to what was required but I doubt it.
Apparently it didn't enter Abnormal Attitude law, continued pitch up will keep THS trimmed esp at slow speed, small excursions pitch down wouldn't give it time to unwind.
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Pitch Trim Authority
The discussion on pitch/power has been enlightening. Guess I shouldn't be surprised there's so much misunderstanding in this group, as just now A&B are admitting power alone does not give you speed to recover from a stall.
Next will be the realization by A&B that trimming the tail to maintain altitude is wrong if your power is limited, as in the case of the Flight Test A330, TK951, etc. I expect some serious limits will be introduced to prevent trimming that presently takes the plane into a stall.
Next will be the realization by A&B that trimming the tail to maintain altitude is wrong if your power is limited, as in the case of the Flight Test A330, TK951, etc. I expect some serious limits will be introduced to prevent trimming that presently takes the plane into a stall.
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opherben
Great, opherben. We appear to be of one mind.
Man Flex
Sorry we're disagreeing, Man Flex. We currently have only the sketchiest information about AF447 - but we have fairly full information about Perpignan. In both cases the THS went to 'full up' and stayed there, whatever the pilot did. The 'difference' is that the (full) report on Perpignan clearly says that the captain repeatedly pushed the stick forward all the way to the stop, and held it there - but the THS just stayed in the 'full up' notch........
Studi
Agree that all those things are relevant, studi. But I would submit that there are at least three other relevant factors.
1. The (known to be sub-standard) Thales pitots. Just the AF447 guys' bad luck that, although these were already being replaced, Air France just hadn't got round to replacing those on their particular aeroplane.
2. The weather. Not just the icing, but probably turbulence as well. Can't have helped.
3. The instruments. The positive 'cascade' of ACARS messages shows that one instrument and 'system' after another was cutting out or in right through the crisis period. I think the most serious criticism one can levy at the BEA is that they didn't say much about that issue in their first report, and say absolutely nothing about it in their recent 'note.' Most of the malfunctioning was probably linked to icing in the pitots and ports. But we'll maybe never know what information the pilots had (or didn't have) as to the aeroplane's attitude, speed, or even its altitude at various times during the crisis. Especially, I fear, if we rely on the BEA to inform us........
In particular, we more or less 'know' that the pilots didn't have any sort of 'natural horizon' to work with. And it's only too possible that, at times anyway, they didn't have an artificial one either........?
RWA wrote,
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document.
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document.
Man Flex
RWA,
I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move.
I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move.
Studi
At the end, it boils down to 4 things:
1. The (known to be sub-standard) Thales pitots. Just the AF447 guys' bad luck that, although these were already being replaced, Air France just hadn't got round to replacing those on their particular aeroplane.
2. The weather. Not just the icing, but probably turbulence as well. Can't have helped.
3. The instruments. The positive 'cascade' of ACARS messages shows that one instrument and 'system' after another was cutting out or in right through the crisis period. I think the most serious criticism one can levy at the BEA is that they didn't say much about that issue in their first report, and say absolutely nothing about it in their recent 'note.' Most of the malfunctioning was probably linked to icing in the pitots and ports. But we'll maybe never know what information the pilots had (or didn't have) as to the aeroplane's attitude, speed, or even its altitude at various times during the crisis. Especially, I fear, if we rely on the BEA to inform us........
In particular, we more or less 'know' that the pilots didn't have any sort of 'natural horizon' to work with. And it's only too possible that, at times anyway, they didn't have an artificial one either........?
What would lead to the attitude indicators failling, RWA?
It has been explained to me in the various other threads on this topic that the attitude indicators are driven by ring laser gyros. I had posited that perhaps the pilots were on a "partial panel" sort of scan, and was advised with some vigor that my supposition was groundless.
There don't appear to be ACARS messages indicating Inertial Reference kicking off, so what anomaly do you think would account for both (all three?) of the "gyros" dropping off?
Or, if you think there was a single failure, the pilot flying, how would the BEA know that his failed and left seat pilot's didn't? Unless the BEA is able to find and publish evidence of an attitude indicator failure, it's hard to point to that as a causal factor.
FWIW (From a summary of how an ADIRU works on wikipedia, consider the source ...) :
As I understand how the ACARS messages were deciphered, it was that ADR faults that stood out, not IR faults. I may misunderstand what was reported.
It has been explained to me in the various other threads on this topic that the attitude indicators are driven by ring laser gyros. I had posited that perhaps the pilots were on a "partial panel" sort of scan, and was advised with some vigor that my supposition was groundless.
There don't appear to be ACARS messages indicating Inertial Reference kicking off, so what anomaly do you think would account for both (all three?) of the "gyros" dropping off?
Or, if you think there was a single failure, the pilot flying, how would the BEA know that his failed and left seat pilot's didn't? Unless the BEA is able to find and publish evidence of an attitude indicator failure, it's hard to point to that as a causal factor.
FWIW (From a summary of how an ADIRU works on wikipedia, consider the source ...) :
An ADIRS consists of up to three fault tolerant ADIRUs located in the aircraft electronic rack, an associated Control and Display Unit (CDU) in the cockpit and remotely mounted Air Data Modules (ADMs).
The No 3 ADIRU is a redundant unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU.
There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data.
An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of attitude and navigation information on their associated Primary Flight Display (PFD) and Navigation Display (ND) screens.
An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
The No 3 ADIRU is a redundant unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU.
There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data.
An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of attitude and navigation information on their associated Primary Flight Display (PFD) and Navigation Display (ND) screens.
An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
Last edited by Lonewolf_50; 13th Jun 2011 at 15:10.