AF447
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Leonardo asks "What force (G) may be deemed necessary to prevent pilot to move his arm at all ?" That depends on the pilot and the layout of the stick. Fighter pilots manage through 9 G somehow.
On the other paw, however, consider holding a very full drink in one hand as you go over a speed bump a little too fast. Now imagine that in turbulence from a CB in three dimensions as you try to reach for the stick. The sidestick has a nice physical layout to ensure stability in turbulence. But you have to get there first and you have to be pretty tightly belted in to keep it stable, I'd bet.
I guess another way to look at it is to imagine you have some springs attached to your wrist exerting 3G accelerations (maybe 10 to 30 pounds force) in random directions every couple seconds as you try to put your hand onto a joystick attached to the arm of your chair. Of course, you desperately don't want to HIT that joystick knocking it full over by accident. Might even 1 G of such acceleration be enough to make it hard to get on the stick accurately and in a hurry?
JD-EE
On the other paw, however, consider holding a very full drink in one hand as you go over a speed bump a little too fast. Now imagine that in turbulence from a CB in three dimensions as you try to reach for the stick. The sidestick has a nice physical layout to ensure stability in turbulence. But you have to get there first and you have to be pretty tightly belted in to keep it stable, I'd bet.
I guess another way to look at it is to imagine you have some springs attached to your wrist exerting 3G accelerations (maybe 10 to 30 pounds force) in random directions every couple seconds as you try to put your hand onto a joystick attached to the arm of your chair. Of course, you desperately don't want to HIT that joystick knocking it full over by accident. Might even 1 G of such acceleration be enough to make it hard to get on the stick accurately and in a hurry?
JD-EE
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Tcas Fault
RE: ACARS msg "TCAS FAULT (2:10)" not yet fully explained?
The exchange in posts #3872, #3873 and #3874 made me go back to BEA's Interim report on AF447 to count how many of these 24 ACARS messages have been marked as "not yet fully explained". I counted 4, and while going to the list it occurred to me how the TCAS FAULT can possibly be linked to pitot failure.
Others in this thread have explained that TCAS uses altitude and does not use airspeed. However, altitude is based on the pressure measured at a static port, which must be corrected for the position error of that port. The position error correction (PEC) is usually expressed as a pressure coefficient cp, which must be multiplied by the dynamic pressure measured at the pitot, to obtain the pressure correction. Some system must have 'reasoned' that since airspeed was unreliable, altitude was also unreliable, and hence TCAS would not be able to perform its intended function.
The PEC occurred to me while reading The Air Caraibe story, where it notes a sudden drop in altitude at the time that CAS and Mach drop, and the altitude steps up by about the same amount when airspeeds come back.
regards,
HN39
The exchange in posts #3872, #3873 and #3874 made me go back to BEA's Interim report on AF447 to count how many of these 24 ACARS messages have been marked as "not yet fully explained". I counted 4, and while going to the list it occurred to me how the TCAS FAULT can possibly be linked to pitot failure.
Others in this thread have explained that TCAS uses altitude and does not use airspeed. However, altitude is based on the pressure measured at a static port, which must be corrected for the position error of that port. The position error correction (PEC) is usually expressed as a pressure coefficient cp, which must be multiplied by the dynamic pressure measured at the pitot, to obtain the pressure correction. Some system must have 'reasoned' that since airspeed was unreliable, altitude was also unreliable, and hence TCAS would not be able to perform its intended function.
The PEC occurred to me while reading The Air Caraibe story, where it notes a sudden drop in altitude at the time that CAS and Mach drop, and the altitude steps up by about the same amount when airspeeds come back.
regards,
HN39
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TCAS failure
In December 2007 EuroControl issued a Safety Reminder Message regarding Low Altitude TCAS II RA's.
They also referred to Guidance for Operators of TCAS Training Programmes, and the initial part of the document is:-
Clause (ii) gives 3 causes of failure, plus the IRS in Note 1.
Take your pick.
mm43
They also referred to Guidance for Operators of TCAS Training Programmes, and the initial part of the document is:-
JAA Administrative & Guidance Material
Section Four: Operations, Part Three: Temporary Guidance: Leaflets (JAR-OPS)
Section 4/Part 3 (JAR-OPS) 11-3 01.02.05
- Criteria: The flight crew member should demonstrate a knowledge and understanding of the ACAS limitations including:
(i) ACAS will neither track nor display non-transponder equipped aircraft, nor aircraft not responding to ACAS Mode C interrogations; and
(ii) ACAS will automatically fail if the input from the aircraft's barometric altimeter, radio altimeter or transponder is lost.
Note 1: In some installations, the loss of information from other on-board systems such as an inertial reference system (IRS) or attitude heading reference system (AHRS) may result in an ACAS failure. Individual operators should ensure their flight crews are aware of what types of failures will result in an ACAS failure.
Section Four: Operations, Part Three: Temporary Guidance: Leaflets (JAR-OPS)
Section 4/Part 3 (JAR-OPS) 11-3 01.02.05
- Criteria: The flight crew member should demonstrate a knowledge and understanding of the ACAS limitations including:
(i) ACAS will neither track nor display non-transponder equipped aircraft, nor aircraft not responding to ACAS Mode C interrogations; and
(ii) ACAS will automatically fail if the input from the aircraft's barometric altimeter, radio altimeter or transponder is lost.
Note 1: In some installations, the loss of information from other on-board systems such as an inertial reference system (IRS) or attitude heading reference system (AHRS) may result in an ACAS failure. Individual operators should ensure their flight crews are aware of what types of failures will result in an ACAS failure.
Take your pick.
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Hi,
So .. seem's the stick is a handicap in this case and a conventional yoke will be more adapted for this kind of situation.
BTW I think a fighter pilot keep allway his hand on stick (assumption mode ON
)
Bye.
On the other paw, however, consider holding a very full drink in one hand as you go over a speed bump a little too fast. Now imagine that in turbulence from a CB in three dimensions as you try to reach for the stick. The sidestick has a nice physical layout to ensure stability in turbulence. But you have to get there first and you have to be pretty tightly belted in to keep it stable, I'd bet.
BTW I think a fighter pilot keep allway his hand on stick (assumption mode ON
)Bye.
So .. seem's the stick is a handicap in this case and a conventional yoke will be more adapted for this kind of situation.
When something is over-analyzed, everything has a handicap that can be "pointed to" as a problem.
The difficulty here is, and I have taken great pains to be patient in explaining the aircraft and how we operate it and what it is like under ordinary and abnormal circumstances, is you just have to take it for granted that Airbus (and Boeing) have actually done some intelligent design work with the basics and believe me, that is really basic stuff that's been around for a very long time.
If I may offer some advise, please do some thinking beforehand and always assume that the people who conceive of, engineer and fly these aircraft know what they're doing and are very, very good at it. JD-EE's response to you was sufficient and well-placed for the layman to comprehend the issue. You're over-analyzing and second-guessing and it's noise, not progress. That's not the way to understand this or any accident or incident.
Just a word to the wise. Most pilots have long since left this thread.
Last edited by PJ2; 25th Jul 2009 at 00:26.
Razoray;
At some point I think they are going to find the wreckage and the recorders. That will inevitably start a whole new round of speculation especially after preliminary readings are posted. Practically everyone, pent up with anticipation, will be suffering from premature release. A few very wise posters here have said that the recorders, if readable, may not provide all the answers either and so another round of tea-leaf reading will unfold. I think it is that moment at which all must keep their head and suspend judgement in favour of curiosity, (he said, knowing it won't happen). As I said in the first thread, we must be extremely circumspect in any new arrival of information and be very aware of the psychology behind "finding cause", the first factor of which is hindsight bias which, I know from personal experience here and in my own work will, (not may), blind one to new notions and original ways of seeing things.
A very long time ago in university, a psych prof said, "Eastern rats perform better for eastern psychologists". That lesson alone was worth the price of admission.
At some point I think they are going to find the wreckage and the recorders. That will inevitably start a whole new round of speculation especially after preliminary readings are posted. Practically everyone, pent up with anticipation, will be suffering from premature release. A few very wise posters here have said that the recorders, if readable, may not provide all the answers either and so another round of tea-leaf reading will unfold. I think it is that moment at which all must keep their head and suspend judgement in favour of curiosity, (he said, knowing it won't happen). As I said in the first thread, we must be extremely circumspect in any new arrival of information and be very aware of the psychology behind "finding cause", the first factor of which is hindsight bias which, I know from personal experience here and in my own work will, (not may), blind one to new notions and original ways of seeing things.
A very long time ago in university, a psych prof said, "Eastern rats perform better for eastern psychologists". That lesson alone was worth the price of admission.
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Well, UNCTUOUS, that flogs away at a different problem, which in this case would have made no practical difference. It points up a potential laxity on the part of the Brazilians and a serious laxity on the part of Dakar. (Note I said potential. I am willing to believe what we saw was a Brazilian presumption of professionality on the part of the Dakar operators who weren't very professional.)
Perhaps yet another fire needs to be lighted under the behinds of the Dakar operators. (Rumors I've heard indicate they are vastly improved from a decade ago or more. What you see is the improved Dakar. So imagine what it must have been then!)
However, in the case present the extra hours before SAR started would not have materially changed the overall results. Some bodies might have been noticed were the SAR aircraft able to get into the area and safely fly around looking at the surface of the ocean. But nobody was likely to be alive and the planes could not effectively search until the storm had abated. If I recall correctly reports from the first days of the aircraft based search included words about how difficult the conditions were due to the abating storm.
Now, there are some other things I draw from this part of the report that hit on my professional interest in RF communications. There are some techniques for RF communications that can ensure that if there is a frequency that can work the aircraft is aware of it and the ground is listening for it. It's a military technique called ALE, Automatic Link Establishment. But selling that technology to the aircraft industry will be difficult and cannot take place here.
I'm just pointing out that almost any part of the BEA report opens avenues for improvement of one kind or another. This is, again, probably not the place to flog these issues, dead horses or not. I could add some notes in private messages if somebody is really interested.
JD-EE
Perhaps yet another fire needs to be lighted under the behinds of the Dakar operators. (Rumors I've heard indicate they are vastly improved from a decade ago or more. What you see is the improved Dakar. So imagine what it must have been then!)
However, in the case present the extra hours before SAR started would not have materially changed the overall results. Some bodies might have been noticed were the SAR aircraft able to get into the area and safely fly around looking at the surface of the ocean. But nobody was likely to be alive and the planes could not effectively search until the storm had abated. If I recall correctly reports from the first days of the aircraft based search included words about how difficult the conditions were due to the abating storm.
Now, there are some other things I draw from this part of the report that hit on my professional interest in RF communications. There are some techniques for RF communications that can ensure that if there is a frequency that can work the aircraft is aware of it and the ground is listening for it. It's a military technique called ALE, Automatic Link Establishment. But selling that technology to the aircraft industry will be difficult and cannot take place here.
I'm just pointing out that almost any part of the BEA report opens avenues for improvement of one kind or another. This is, again, probably not the place to flog these issues, dead horses or not. I could add some notes in private messages if somebody is really interested.
JD-EE
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TCAS Quandary
mm43:
(i) This will not cause or result in TCAS Fail.
(ii) A sudden change in indicated altitude as experienced by Air Caraibe will not trigger TCAS Fail. There was no ACARS report of radio altimeter nor transponder Fail; hence, these do not account for the TCAS Fail. Moreover, there were no reports of ADR Altitude Fail.
1. IRU is inconsequential to Collins TCAS. IRU Fail might trigger Honeywell TCAS Fail. That, however, requires failure of both #1 and #3 IRU, as #3 is automatic backup. Does AF 330 fleet fly Collins TCAS, or Honeywell TCAS?
I agree with the BEA: TCAS Fail report remains unexplained/unrelated to the other Fail reports.
HN39
If the measured altitude was good enough to display to the pilot, it was good enough to report to the transponder. From what little I've seen of airspeed correction tables in other aircraft, they are significant only at high angles of attack, and not at cruise.
Did Air Caraibe have a TCAS Fail during their event?
GB
...(i) ACAS will neither track nor display non-transponder equipped aircraft, nor aircraft not responding to ACAS Mode C interrogations; and
(ii) ACAS will automatically fail if the input from the aircraft's barometric altimeter, radio altimeter or transponder is lost.
Note 1: In some installations, the loss of information from other on-board systems such as an inertial reference system (IRS) or attitude heading reference system (AHRS) may result in an ACAS failure. Individual operators should ensure their flight crews are aware of what types of failures will result in an ACAS failure.
--------
mm43 statement:
Clause (ii) gives 3 causes of failure, plus the IRS in Note 1.
(ii) ACAS will automatically fail if the input from the aircraft's barometric altimeter, radio altimeter or transponder is lost.
Note 1: In some installations, the loss of information from other on-board systems such as an inertial reference system (IRS) or attitude heading reference system (AHRS) may result in an ACAS failure. Individual operators should ensure their flight crews are aware of what types of failures will result in an ACAS failure.
--------
mm43 statement:
Clause (ii) gives 3 causes of failure, plus the IRS in Note 1.
(ii) A sudden change in indicated altitude as experienced by Air Caraibe will not trigger TCAS Fail. There was no ACARS report of radio altimeter nor transponder Fail; hence, these do not account for the TCAS Fail. Moreover, there were no reports of ADR Altitude Fail.
1. IRU is inconsequential to Collins TCAS. IRU Fail might trigger Honeywell TCAS Fail. That, however, requires failure of both #1 and #3 IRU, as #3 is automatic backup. Does AF 330 fleet fly Collins TCAS, or Honeywell TCAS?
I agree with the BEA: TCAS Fail report remains unexplained/unrelated to the other Fail reports.
HN39
...position error of that port. The position error correction (PEC) is usually expressed as a pressure coefficient cp, which must be multiplied by the dynamic pressure measured at the pitot, to obtain the pressure correction. Some system must have 'reasoned' that since airspeed was unreliable, altitude was also unreliable, and hence TCAS would not be able to perform its intended function.
The PEC occurred to me while reading The Air Caraibe story, where it notes a sudden drop in altitude at the time that CAS and Mach drop, and the altitude steps up by about the same amount when airspeeds come back.
The PEC occurred to me while reading The Air Caraibe story, where it notes a sudden drop in altitude at the time that CAS and Mach drop, and the altitude steps up by about the same amount when airspeeds come back.
Did Air Caraibe have a TCAS Fail during their event?
GB
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LeandroSecundo - I have never used a side-stick flight control but have used several 'side-stick system controls' in various fighting machines. Turbulence is your biggest problem and the decider is how 'sensitive' a particular control is to a random input. The 'control column' (yoke) is a very coarse control and turbulence does not create too much of a problem. If the AB side-stick is highly geared and hand support is not adequate you may have problems. Control stick damping is another design consideration. A little flying in a British 'Whirlwind' helicopter showed me that the 'stick' was not 'mass balanced' and if it fell over to one side when you let go the heli followed it
Moving a 'joystick' at 7g+ smoothly takes a lot of effort. However the 'g' we are looking at in this case are few.
Moving a 'joystick' at 7g+ smoothly takes a lot of effort. However the 'g' we are looking at in this case are few.
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TCAS again
RE: Greybeard (#3891)
No, the Air Caraibe Note does not mention TCAS FAULT. Good point, thank you for replying.
Nevertheless, the altitude steps remain puzzling. On page 2 of the ACA Note:
On page 4:
So the PRIM's don't fault the altitude, they fault first one, then all three ADR's
(F/CTL ADR DISAGREE), apparently because of faulty airspeed parameters.
Note however on page 9 of the ACA Note, that "le système <<AUTO FLIGHT>>" also monitors the ADR's, using different rejection criteria:
Would it be far-fetched to imagine that yet another system (for example TCAS) similarly monitors altitude, applying its own rejection criterion?
Finally, in the ACA case CAS dropped to 85 kt, what if it dropped to zero in the case of AF447?
regards,
HN39
Did Air Caraibe have a TCAS Fail during their event?
Nevertheless, the altitude steps remain puzzling. On page 2 of the ACA Note:
A 22H22 et 59S, on enregistre une diminution très rapide de la « CAS », du mach et de l'altitude (correction de mach). Ces paramètres passent respectivement de 273KT à 85KT, M0.80 à M0.26 et de 35000FT à 34700FT.(...)
A 22H24 et 25S, la «CAS» augmente de 111KT à 275KT, le mach retrouve sa valeur initiale M0.80 et l'altitude augmente brutalement passant de 34200FT à 34500FT.
NB1, seuils pour l'élimination d'une «ADR» : Altitude 3000FT pendant 1S, mach 0.05 pendant 10S, « CAS » 16KT pendant 10S, TAS 16KT pendant 10S, pression totale 20HPA pendant 10S, « AOA » 3.6° pendant 1S, pression statique 5HPA pendant 1S.
NB2, seuils pour l'élimination des deux « ADR » restantes : Altitude 3000FT pendant 1S, mach 0.05 pendant 1S, « CAS » 16KT pendant 1S, TAS 16KT pendant 1S, pression totale 20HPA pendant 18, « AOA » 3.6° pendant 1S, pression statique 5HPA pendant 1S.
NB2, seuils pour l'élimination des deux « ADR » restantes : Altitude 3000FT pendant 1S, mach 0.05 pendant 1S, « CAS » 16KT pendant 1S, TAS 16KT pendant 1S, pression totale 20HPA pendant 18, « AOA » 3.6° pendant 1S, pression statique 5HPA pendant 1S.
(F/CTL ADR DISAGREE), apparently because of faulty airspeed parameters.
Note however on page 9 of the ACA Note, that "le système <<AUTO FLIGHT>>" also monitors the ADR's, using different rejection criteria:
NB4, seuils pour le rejet d'une «ADR» : «CAS» 20KT pendant 0.45S, mach 0.04 pendant 0.45S, altitude 400FT pendant 0.45S.
Finally, in the ACA case CAS dropped to 85 kt, what if it dropped to zero in the case of AF447?
regards,
HN39
Last edited by HazelNuts39; 26th Jul 2009 at 16:34. Reason: Corrected an error re ECAM msg EPR MODE FAULT
BOAC;
The AB sidestick fits the hand and the arm is supported by a very adjustable arm-wrest, (up-down, high/low angle) and the sidestick can be easily controlled from the wrist or even just the fingers if placed at the top of the stick. It is heavily damped. My point was, this is a very good control system which is natural and easy to get accustomed to and use even in heavy turbulence. If we are discussing severe/extreme turbulence or jet-upset conditons however, no aircraft is immune to high 'g' loads in terms of reaching/moving the controls, column/wheel or sidestick, especially with the likelihood of flight bags and everything else that's not tied down flying around the cockpit, (possibly in the dark)...
For background info, the sidestick does not move ailerons or elevators. The sidestick requests a roll-rate and a 'g' load. The FCPCs interpret the requests and provide the necessary commands to the servos, through the C* (fbw) laws which have been discussed. This is essentially the same as CWS - Control Wheel Steering - not sure the Boeing has it but the L1011 did.
The process is, for practical purposes, instantaneous - no lag between request and response. Also, the autoflight system, being fbw, keeps the aircraft in the last "known" attitude until another input is made, which, if one thinks about it, makes complete sense. One can "set" the attitude, leave the airplane with hand off the stick and the fbw autoflight system will "keep" the attitude until another input is made changing the attitude.
Even in heavy turbulence, the system (fbw, without the a/p engaged) will attempt to keep the aircraft at the last position established. You mention sensitivity levels - that's not so much an issue with the AB sidestick as understanding what's going on out on the wing - while the full-time fbw system is trying to maintain the last aircraft attitude, the FCPCs will also be interpreting the second-by-second sidestick manual "requests" by the flying pilot so will be busy satisfying both inputs.
For these reasons, the notion of "coarseness" is not so much applicable in understanding the system as is an understanding of what the ailerons are doing out there on the wing in response to all inputs, fbw & manual, and why. There are many cases in which over-controlling is an issue in the AB for exactly these reasons., (I note the thread on the Hamburg accident).
I have posted my biases lots of times - I am not a convinced Airbus pilot trying to "sell" the design or tout its benefits over other types. I'm describing the machine from one pilot's point of view. There are in my view some things that this design must answer for but with solid training, adherence to standards and continuous testing and recurrent training, handling the Airbus is a non-event. It was this level of appreciation for the design that I was making a point about. That said, your own experience re the stick in the Whirlwind, albeit a long way from the AB design, does cause one to sit back a moment.
The AB sidestick fits the hand and the arm is supported by a very adjustable arm-wrest, (up-down, high/low angle) and the sidestick can be easily controlled from the wrist or even just the fingers if placed at the top of the stick. It is heavily damped. My point was, this is a very good control system which is natural and easy to get accustomed to and use even in heavy turbulence. If we are discussing severe/extreme turbulence or jet-upset conditons however, no aircraft is immune to high 'g' loads in terms of reaching/moving the controls, column/wheel or sidestick, especially with the likelihood of flight bags and everything else that's not tied down flying around the cockpit, (possibly in the dark)...
For background info, the sidestick does not move ailerons or elevators. The sidestick requests a roll-rate and a 'g' load. The FCPCs interpret the requests and provide the necessary commands to the servos, through the C* (fbw) laws which have been discussed. This is essentially the same as CWS - Control Wheel Steering - not sure the Boeing has it but the L1011 did.
The process is, for practical purposes, instantaneous - no lag between request and response. Also, the autoflight system, being fbw, keeps the aircraft in the last "known" attitude until another input is made, which, if one thinks about it, makes complete sense. One can "set" the attitude, leave the airplane with hand off the stick and the fbw autoflight system will "keep" the attitude until another input is made changing the attitude.
Even in heavy turbulence, the system (fbw, without the a/p engaged) will attempt to keep the aircraft at the last position established. You mention sensitivity levels - that's not so much an issue with the AB sidestick as understanding what's going on out on the wing - while the full-time fbw system is trying to maintain the last aircraft attitude, the FCPCs will also be interpreting the second-by-second sidestick manual "requests" by the flying pilot so will be busy satisfying both inputs.
For these reasons, the notion of "coarseness" is not so much applicable in understanding the system as is an understanding of what the ailerons are doing out there on the wing in response to all inputs, fbw & manual, and why. There are many cases in which over-controlling is an issue in the AB for exactly these reasons., (I note the thread on the Hamburg accident).
I have posted my biases lots of times - I am not a convinced Airbus pilot trying to "sell" the design or tout its benefits over other types. I'm describing the machine from one pilot's point of view. There are in my view some things that this design must answer for but with solid training, adherence to standards and continuous testing and recurrent training, handling the Airbus is a non-event. It was this level of appreciation for the design that I was making a point about. That said, your own experience re the stick in the Whirlwind, albeit a long way from the AB design, does cause one to sit back a moment.
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Originally Posted by PJ2
That said, your own experience re the stick in the Whirlwind, albeit a long way from the AB design, does cause one to sit back a moment.
.Apologies if you have misinterpreted my post - I was trying to give a general answer to LS with just a 'dash' of AB, not to invoke any criticism.I have, as I said, never used it.
Last edited by BOAC; 25th Jul 2009 at 16:45.
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The two Air Caraïbe A330, the AF 908, the NW planes did not experience any TCAS problem during the corrupted airspeeds events (slight altitude bias, a few 100 ft, -300 ft in the Air Caraïbe case). In the AF 447 case, it could be that the Pitot-static duo was compromised more severely/time than in the other cases ? Or the TCAS problem has nothing to do with the Pitot phenomenology (not my view).
-In the last evening TV news, there was some news about the analysis beginning at the CEAT: Journaux télévisés en vidéo - France 2 at ~12:40, you get a close up on a map of the plane showing colored seats that were occupied by the passengers who were recovered.
-Thank you Unctuous for the interesting scenario: BEA interim report* *Extract
This is speculation, but if the flight data are not recovered, the BEA will also be left to speculate
Speculating is not bad, as long as it also provides the means to be tested at one point (speculating is probably the most creative part in science, and... nice etymology).
It is speculated/hypothetized that:
_____________
e. Disorientation (normally following flight instrument failure)
f. Thunderstorm encounter
g. Stalling or Mach Crit encounters near coffin corner (probably induced by an incorrect manual response to a warning alert - and involving a Flight Law mode change degradation).
The last two instances are the two likely scenarios for AF447. The history of Thales pitots and the similarity of the recorded fault sequences transmitted by ACARS is pointing relentlessly at scenario g.
_____________
It is also speculated that the A/THR had possibly already narrowed the upper aerodynamic margin just before it was auto-disengaged along with the A/P when the cascade of ECAM alerts began. Then the pilots may have further reduced their margin (by reacting in an opposite manner to the Air Caraïbe crew) and got very vulnerable to the turbulences (that may have increased as they were approaching the main Cb cell within the mesocluster). Their stress was probably increased by a sudden & unusual event (a cascade of aural/visual alerts), their attention was split between failure analysis & solving, procedures/check lists impossible (frustration) to apply due to time constraints & very confusing about stall alarms (see Air Caraïbe), manual flight, monitoring met conditions,... At night, in the absence of outside visual clues, an increased workload with the eyes scanning rapidly varied parts of the cockpit and attention split, spatial disorientation may have played a role as suggested ? No pilot should be placed in such a situation (intrumental & procedural ambiguities) and at worst, if this can't be avoided, they should be trained for that:
-As automation grows within the cockpit, the failures get more complex, potentially confusing, and pilots have also to become flight engineers. I don't know about how they are trained for complex system failures analysis (all the ways for otto to get crazy) but don't you think that ground simulation training should also implement false alarms ? I haven't be able to find any pilot whose regular training in ground simulations involves unreliable airspeeds and associated false alarms
Hope this is because pilots have flown away from here. Sorry for not being concise.
Jeff
-In the last evening TV news, there was some news about the analysis beginning at the CEAT: Journaux télévisés en vidéo - France 2 at ~12:40, you get a close up on a map of the plane showing colored seats that were occupied by the passengers who were recovered.
-Thank you Unctuous for the interesting scenario: BEA interim report* *Extract
This is speculation, but if the flight data are not recovered, the BEA will also be left to speculate
Speculating is not bad, as long as it also provides the means to be tested at one point (speculating is probably the most creative part in science, and... nice etymology). It is speculated/hypothetized that:
_____________
e. Disorientation (normally following flight instrument failure)
f. Thunderstorm encounter
g. Stalling or Mach Crit encounters near coffin corner (probably induced by an incorrect manual response to a warning alert - and involving a Flight Law mode change degradation).
The last two instances are the two likely scenarios for AF447. The history of Thales pitots and the similarity of the recorded fault sequences transmitted by ACARS is pointing relentlessly at scenario g.
_____________
It is also speculated that the A/THR had possibly already narrowed the upper aerodynamic margin just before it was auto-disengaged along with the A/P when the cascade of ECAM alerts began. Then the pilots may have further reduced their margin (by reacting in an opposite manner to the Air Caraïbe crew) and got very vulnerable to the turbulences (that may have increased as they were approaching the main Cb cell within the mesocluster). Their stress was probably increased by a sudden & unusual event (a cascade of aural/visual alerts), their attention was split between failure analysis & solving, procedures/check lists impossible (frustration) to apply due to time constraints & very confusing about stall alarms (see Air Caraïbe), manual flight, monitoring met conditions,... At night, in the absence of outside visual clues, an increased workload with the eyes scanning rapidly varied parts of the cockpit and attention split, spatial disorientation may have played a role as suggested ? No pilot should be placed in such a situation (intrumental & procedural ambiguities) and at worst, if this can't be avoided, they should be trained for that:
-As automation grows within the cockpit, the failures get more complex, potentially confusing, and pilots have also to become flight engineers. I don't know about how they are trained for complex system failures analysis (all the ways for otto to get crazy) but don't you think that ground simulation training should also implement false alarms ? I haven't be able to find any pilot whose regular training in ground simulations involves unreliable airspeeds and associated false alarms
Hope this is because pilots have flown away from here. Sorry for not being concise.Jeff
Last edited by Hyperveloce; 25th Jul 2009 at 16:48.
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As automation grows within the cockpit, the failures get more complex, potentially confusing, and pilots have also to become flight engineers.
This is a very sad example of "industrial evolution" .
Money, Profit, Money, Profit.......
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Fully agree!
This is a very sad example of "industrial evolution" .
Money, Profit, Money, Profit.......
This is a very sad example of "industrial evolution" .
Money, Profit, Money, Profit.......
FSLF
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@fslf
Feel free to qualify my post to whatever you want.
I'm sorry if it wasn't clear enough.
The price for highly automatic/sophisticated FD isn't zero. I was refering to Hyperveloce's post in respect to very basic FD like 727/747 classic versus very complex FD like AB fly by wire.
Kind regards
hetfield
727/A300/A340/A320
And yes, sometimes SLF
Feel free to qualify my post to whatever you want.
I'm sorry if it wasn't clear enough.
The price for highly automatic/sophisticated FD isn't zero. I was refering to Hyperveloce's post in respect to very basic FD like 727/747 classic versus very complex FD like AB fly by wire.
Kind regards
hetfield
727/A300/A340/A320
And yes, sometimes SLF
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How to judge whether a stall alarm is justified or not ?
...if you have lost a major indicator like airspeeds and if you are at high altitude with a little aerodynamic margin (GPS ground speed insufficient) and no visibility ?
would the pich & thrust interplay do it ? a few days ago, a pilot asked to the other pilots: flying without airspeeds at FL350 with an AoA~4°, your pich/altitude remain well under control, would you think you are approaching a stall ? (as far as I understand). would such a behaviour (evolution) of the pich/altitude (given the thrust, AoA & altitude) be a non ambiguous indication of a sufficient airspeed ?
if you have more time (assuming you are not subjected to multiple stall alarms), can you assess your aerodynamical authority by inducing a smooooooth vertical manoeuver ? (loosing a bit of altitude and stabilizing it with a slight attempt to regain altitude to assess the airframe authority).
Would you see means to appreciate (swiftly) whether a stall alarm is justified or not ? How will you do if it happens to you ?
Jeff
PS) Automation is not bad (simply you can't rely on it and you have to know it intimately as it is a critical part of your plane) and sometimes, men & automata (Alpha prot.) collaborate for the best:
http://www.ntsb.gov/events/2009/Weehawken-NJ/13-Lutz-presentation.pdf (I know, this is an Airbus presentation, but...)
PPS) today is Bleriot's 100th anniversary, a man not bothered by autmated systems: Le 25 juillet 1909 .The same flight was performed today
would the pich & thrust interplay do it ? a few days ago, a pilot asked to the other pilots: flying without airspeeds at FL350 with an AoA~4°, your pich/altitude remain well under control, would you think you are approaching a stall ? (as far as I understand). would such a behaviour (evolution) of the pich/altitude (given the thrust, AoA & altitude) be a non ambiguous indication of a sufficient airspeed ?
if you have more time (assuming you are not subjected to multiple stall alarms), can you assess your aerodynamical authority by inducing a smooooooth vertical manoeuver ? (loosing a bit of altitude and stabilizing it with a slight attempt to regain altitude to assess the airframe authority).
Would you see means to appreciate (swiftly) whether a stall alarm is justified or not ? How will you do if it happens to you ?
Jeff
PS) Automation is not bad (simply you can't rely on it and you have to know it intimately as it is a critical part of your plane) and sometimes, men & automata (Alpha prot.) collaborate for the best:
http://www.ntsb.gov/events/2009/Weehawken-NJ/13-Lutz-presentation.pdf (I know, this is an Airbus presentation, but...)
PPS) today is Bleriot's 100th anniversary, a man not bothered by autmated systems: Le 25 juillet 1909 .The same flight was performed today
Last edited by Hyperveloce; 25th Jul 2009 at 18:50.
No worries BOAC - it was an opportunity to clarify, which is always a welcome and needed thing when discussing this complex machine!
Rog' on the not-sitting-back-for-too-long...the image made my morning
Rog' on the not-sitting-back-for-too-long...the image made my morning