|
just sayin'
When the AP disconnected the PF pitched up, which eventually caused the plane to stall. Not sure why he did that, he should have just essentially left the controls alone and flown the pitch attitude at auto pilot disconnect.
But, I have no idea why the programming of the aircraft flight control systems silenced the stall warning system when in fact the aircraft was stalled. Whatever stall warning system is installed in that aircraft should have been active while the aircraft was stalled period, no excuses. |
Doze
Whilst in Autopilot, notice the oscillation of the THS, it varies 1-2 degrees very consistently, and smoothes when PF inputs NU. It also flies at three degrees NOSE DOWN during the same time frame. Stick obviously caged in spring tension. Am I seeing some "Weather" reactions? Or an anomalous "Buzz"? Of course it is not flutter, but flutter does present that way....... |
Hi,
DW Thank's for post here the graphic. In the timeline transcript the BEA write: Between 2H10min07 and 2H10min18 the vertical speed increase to 5200 ft/min That's indeed true .. and when you put it in correlation with the graphic you see immediately it's a vertical speed to down (loss of altitude) Vertical speed used by BEA in transcript is misleading less the down qualification (as in the timeline the BEA don't give the difference of altitude during the time gap) So I can at least understand a little more why the PF give a up command (stick back) as a vario of 5200 ft/min down is not a negligible vertical speed ... http://i.imgur.com/uYwUs.jpg |
@jcjeant
Sorry, but not so - look at the altitude trace. From 2:10:07 to 2:10:18 the aircraft is climbing. It reaches the apogee of the climb at about 2:11:15 and then begins to fall. |
DozyWannabe
ColganAir: I do recall that incident. They said that he had been recently trained to stick up because under certain circumanstances. So he had both the reflex and some training indicating it was the right thing. Like you say it was lower so they had no second chance after the initial nose up stall response. Clearly the problem with a stall is that you must do the opposite of normal flight i.e. a/c drops so I nose up to get back up whereas a stall - i have stalled, nose down to get my wings flying and generate lift. It makes me think that stall recovery is ripe for automation, so long as above a certain height, AoA sensors valid, etc. We want the pilot to do something counter intuitive, quickly. Stall recovery is not practiced often enough to become familiar let alone a reflex except for special pilot categories. Thanks for the graphic and scaling. Has anyone figured out why the speeds spike up and down between 400kts and 50kts. Looks really odd. If the PFD showed radical jumping then it confused them even more. |
Hi,
@jcjeant Sorry, but not so - look at the altitude trace. From 2:10:07 to 2:10:18 the aircraft is climbing. It reaches the apogee of the climb at about 2:11:15 and then begins to fall. http://i.imgur.com/aOtC5.jpg |
It's an initial step down, for sure (at 2:10:07 or thereabouts), possibly due to turbulence - but from that point onwards the aircraft is climbing, and at 2:10:18 the climb is well established.
@bearfoil - I reckon that's the autotrim trying to ride the weather. |
jcjeant....... (vertical Speed)
And it can be understood at a gut level to be consistent with an overspeed dive. (As well as STALL). More so than a STALL, actually. Nose first, she slips quickly down. Butt first, less logical for the reads they saw. I have never been in a Stall long enough for it to get loud. Were they all thinking "Dive", at one point? A-6 guy. See up here. I think no bumps on the ss? That would accede way too much control to the Pilots. The control is like the one on the 402, a big bakelite frisbee that gives elbow cramps on short final. A WHEEL! |
Does the Airbus have a stab trim button on the sidestick? If it does, there is absolutely NO sane reason why, in almost 3 minutes, at least one of the pilots would not take control and push both the stick and the trim button forward to try to break the stall. There is also NO sane reason to explain why those pilots would expect the plane to NOT be stalled with the excess pitch attitude they had.
Regardless of any control laws or design flaws, there was PLENTY of time to get the airplane out of the stall, and they failed to even make a reasonable attempt to do that. THAT is sad! |
Hi,
It's an initial step down, for sure (at 2:10:07 or thereabouts), possibly due to turbulence - but from that point onwards the aircraft is climbing, and at 2:10:18 the climb is well established. @bearfoil - I reckon that's the autotrim trying to ride the weather. So .. and despite stick up commands (nose up) .. the aircraft still not climbing all this gap of time .. Speak of little turbulence .. lol .. it's a downdraft for sure .. and a good .. And I repeat .. the BEA transcript is misleading .. until you put the graphic in correlation ... http://i.imgur.com/YECUr.jpg |
Originally Posted by jcjeant
Look better at the altitude line (blue first up table) .. it's a step down ... sorry but it's very evident .. with my spectacles or not
Second, the change of pitch (reduction) that was recorded after 0209:58 is due to the crew reduction to Mach 0.80, followed by a change of N1 of -16% in 8 seconds. Pitch decreased from +1.8° to 0° in three seconds (0210:00-0210:03). 2 h 09 min 58 La gestion de la vitesse passe de managée à sélectée. Le Mach sélecté est 0,8. 2 h 10 L’assiette longitudinale diminue de 1,8° vers 0° en 3 secondes. En 8 secondes, les N1 commandés et les N1 passent de 100 % à 84 %. |
Funny, that "staccato" buzz on the trace. Weather is that short term, and Consistent?
Another opinion, before I go all VS? |
http://i1088.photobucket.com/albums/...r-vs-munge.png
That's the Vertical speed trace. The slight drop at 2:10:07 is nowhere *near* -5000ft/min. |
Hi,
That's the Vertical speed trace. The slight drop at 2:10:07 is nowhere *near* -5000ft/min. |
Is Vs calculated on anomalous readings? Or raw data?
The drop looks like less than 700fpm. The vertical speed trace is beyond my meager comprehension, are those fluctuations due UAS, or are those, they're not actual, are they? That THS graphic is (they all are) full of bit rash, but the zipper trace is not bit rash, what is that dang deal, dozy? Turbine D? Stop me. What is that? Because if it is real, the THS was oscillating 1+ degrees once per second. Right up til it quit. It looks at least noisy, if not mechanical. A one second wave generated by the one second sampling/trigger that repeated? How long? The aft cabin must have shook like a wet dog. |
@bearfoil - The graphic is too far zoomed-out and too low-resolution to draw any conclusions from anything other than large and significant trends. I don't think you're seeing quick fluctuations in THS angle so much as you are seeing the graphics renderer trying to cope with displaying the data at that granularity.
I'd say the extreme AoA was probably fouling the static data from 02:11:47 onwards. |
I think that is reasonable, and thanks for your patience. What makes it suspicious to me is its connection with a mechanism that exhibits that precise artifact in rare though actual circumstances. We'll see.
Statics? Quite agree. especially with the ROLL coupling the AoA. For that matter, the airframe was in very untrod territory, all bets off. Just to be clear, I am noting the zipper trace at prior to ap loss. I do not take that to be AoA fluctuations, there isn't time enough between 'cycles'. |
Originally Posted by jcjeant
In the timeline transcript the BEA write:
Between 2H10min07 and 2H10min18 the vertical speed increase to 5200 ft/min That's indeed true .. and when you put it in correlation with the graphic you see immediately it's a vertical speed to down (loss of altitude) Vertical speed used by BEA in transcript is misleading less the down qualification (as in the timeline the BEA don't give the difference of altitude during the time gap) So I can at least understand a little more why the PF give a up command (stick back) as a vario of 5200 ft/min down is not a negligible vertical speed ... But sure, right before this point, two seconds before precisely, it decreased, say at -18,000 ft/min in one second... (or you can even make a 10 times much bigger number if you use 1/10th of second), because it was the false loss of about 300 ft due to UAS at 0210:05. . ADR 1 (altitude, ft) 0210:00 -> 35,044 0210:05 -> 35,024 (UAS after this point, barely no mach correction of static pressure) 0210:09 -> 34,664 (ISIS: 34,900) 0210:11 -> 34,636 (lowest altitude recorded) 0210:17 -> 34,976 0210:25 -> 35,856 Explanations, BEA report #2 p.48: (they should have anticipated that far the cover up of those tracks "issues") http://takata1940.free.fr/static.jpg |
Hi,
Explanations, BEA report #2 p.48: (they should have anticipated that far the cover up of those tracks "issues") |
To everyone here
When a french pilot said GAUCHISSEMENT he speak 's about ROLL
That common sense |
Originally Posted by jcjeant
I wonder if the PF had knowledge of this phenomena ..
|
Hi intruder
On AIRBUS
Side stick are fitted with priority button wich allow neutralizing other side stick when operated associated with call " PRIORITY L or R Its not allowed using both side stick a the same time, in case if not there is also a call "DUAL INPUT" On pedestal close to throtlle both side a big wheel trim for manual setting wich is also operating automatically . |
If they felt they were fast and descending perhaps they thought this was a high speed stall warning? In which case relaxing the back stick but still mantaining some might make sense.
|
Intruder, please do some home work :
Does the Airbus have a stab trim button on the sidestick? there was PLENTY of time to get the airplane out of the stall they failed to even make a reasonable attempt to do that. |
IMHO the ignorance of the audible stall warning could only be caused by the pilots assuming, that the stall warning would be triggered by too low speed (instead of AoA).
Speed incorrect -> Stall warning -> ignore it When the speed came back they had stalled the plane and the speed stayed low => assumption: still incorrect. Why should they believe now, that the speed was more correct than before? Why should they believe with all this confusing stuff around them, that any other indication was more correct? The speed even became lower and lower and the stall warning disappeared at some point. -> continue to ignore all this It remains the question: why did he pull so much? where is the no speed indication check list, and so on. Also: pitch is not AoA! |
The real kicker, I suspect, is the timing of the captain's re-entry to the cockpit - almost exactly at the point where the continuous stall alarm switched off. I wonder what he would have done if he'd heard nearly a minute's worth of stall warning.
|
Originally Posted by GerardC
(Post 6616267)
Each time they made a "reasonnable attempt" to solve their problem (ND), the stall warning kicked in again and THAT is VERY, VERY sad !
Only once does the return of the stall warning match a nose-down input (2:12-35-2:12:38). In all other cases the stick is either neutral or back when the stall warning returns, except for once at the very end, where the PNF has already been more-or-less holding nose-down for 15 seconds. @Mimpe - The Hudson aircraft was an A320. Also, while Sullenberger had the piloting chops that ditched them safely in the river, he was the first to praise F/O Skiles and the rest of his crew for a correct and professional response to the situation. |
lonewolf...my concern is that PF may well have been more than just worried about overpeed.Its clear he had lost his initial crucial scan,was overcontrolling, and I feel as the aircraft slowed with zoom climb,may well have crossed the rubicon of lapsing into a sensory interpretation of what the aircraft was doing.I feel the decleration he was experiencing in the late stages of the climb, heightened by marked anxiety,probably ended in a somatogravic illusion of acceleration, and persistent nose up inputs unto death.
The rest was history, as the situation required immediatre transfer of control to PNF, whose spatial orientation and understanding of the situation appears clearly superior throughout. No time for egalitarian social norms. When the birds hit the 737 over Manhattan, pretty much the first action fronm Sullenberger was.." My Aircraft". |
it's really sad and unfortunate
i believe if the crews had known beforehand that they had Unreliable Air Speed, they would have flown the last known power setting and Pitch, ignoring all the other warnings.... i strongly believe they were very confused... if they had recognised it as Unreliable Air Speed earlier , and just fly Attitude + Power, and maintained it until at least out of the weather, things would have been much better. it's not easy to recognise Unreliable Airspeed...... and getting inside some massive weather leaves you very little time to stop and think ,before confirming what's the problem... string of unfortunate events happening at the exact moment... |
thanks for the correction Dozy.
I do remember Sullys F/O cooperated immediately and seamlessly - a great result for all. Sully's book was a wonderful read, and there was a lot to learn from it. |
Originally posted by "Dozy"
Not true : see AF447 wreckage found . Only once does the return of the stall warning match a nose-down input (2:12-35-2:12:38). In all, 4 stall warning activations. Would not YOU be confused : nose down -> stall ; nose up -> NO stall. |
At 02:10:16Z the aircraft goes into "Alternate Law". What was the trigger? The faulty pitots? Just curious.
Also, after the pitots started working again why does the system not re-arm the flight envelope protections. With the narrow flight envelope at those heights it seems dangerous to subject pilots to unprotected flight for any longer than absolutely inevitable. |
Hi,
Le BEA ne prend pas en compte l'incohérence des alarmes de décrochage !? | Communiqués et conférences de presse Le BEA ne prend pas en compte l'incohérence des alarmes de décrochage !? Mise à jour le Mercredi, 03 Août 2011 10:58 Mercredi, 03 Août 2011 10:03 http://www.asso-af447.fr/templates/a...ages/trans.gif http://www.asso-af447.fr/images/M_im...rintButton.png Suite à la récente diffusion dans la presse (>> lien vers l'article) d’une information relative à la non publication d’une recommandation de sécurité aérienne par le Bureau d’Enquêtes et d’Analyses, l’Association Entraide & Solidarité AF447 exprime son vif mécontentement et son extrême indignation quant à cette mascarade. En effet, malgré un délai d’analyse très court du troisième rapport du BEA, nous notons que les pertes concomitantes des données de vitesse et d’incidence génèrent une situation particulièrement critique, et que cette situation, à ce jour, n’a toujours pas été expliquée techniquement. Ainsi, l’absence d’alarme décrochage (Stall) laisse supposer aux pilotes que la situation aérodynamique de l’appareil s’améliore, alors qu’en réalité, elle empire. De la même manière, l’apparition de cette alarme et son respect dans le cadre de la procédure alors en vigueur, sans visualisation possible de l’incidence, conduit les pilotes à augmenter la poussée des réacteurs (TO.GA) et par conséquence, augmenter encore l’incidence de l’aéronef. A cela, nous devons ajouter la différence de procédure « IAS Douteuse » relativement à la manoeuvre dite d’urgence (Memory Items), celle d’Air France indiquant de respecter l’alarme décrochage, alors que celle d’Airbus ne le précise pas. Ainsi, considérant que pour des raisons de sécurité évidentes des actions immédiates doivent être entreprises, nous demandons qu’une recommandation soit émise par le BEA, pour d’une part, informer les pilotes, et d’autre part, pour adapter les procédures aux remarques précitées. Il n’est nul besoin d’attendre les hypothétiques conclusions d’un groupe « facteurs humains » pour réagir uniquement sur des critères de bon sens. Il est également à remarquer que les recommandations de l’autorité d’enquêtes ne sont affectées d’aucun délai de réalisation, ce qui semble incompatible avec la notion de réactivité inhérente à la sécurité aérienne. Au vu de ces évènements à la partialité affichée, il est primordial que l'Association obtienne une réponse favorable à sa requête par voie judiciaire pour obtenir l’intégralité des données des enregistreurs de vol. Enfin, nous condamnons fermement ce triste épisode qui jette définitivement le discrédit sur l’investigation technique et qui génère une crise de confiance sans précédent envers les autorités d’enquêtes. La précipitation avec laquelle ces autorités et ces responsables ont accusé les pilotes sans aucune réflexion préalable avait alerté notre suspicion. Nous avons maintenant confirmation que les affirmations émanant de la tutelle du BEA étaient non seulement prématurées, dépourvues d’objectivité, partiales et très orientées vers la défense d’Airbus. Ceci est totalement indécent et inacceptable. Les victimes de l’AF447 ne méritent pas un tel outrage. Les familles de victimes dénoncent un véritable scandale, qui viole leurs droits à la vérité !... Pour l’Association Entraide & Solidarité AF 447 Le Président Robert Soulas The BEA does not take into account the inconsistency of the stall warning!? Updated on Wednesday, August 3, 2011 10:58 Wednesday, August 3, 2011 10:03 Following the recent press coverage (>> link to the article) of information on the non publication of a recommendation by the Office of Aviation Safety Investigations and Analysis, Solidarity & Mutual Aid Association 447 expresses strong dissatisfaction and extreme indignation at this travesty. Indeed, despite a very short period of analysis of the third report of the BEA, we note that the concomitant loss of data of speed and impact generated a particularly critical situation, and this situation to date, has still not explained technically. Thus, the absence of alarm stall (Stall) suggests the pilots that the situation is improving aerodynamics of the aircraft, when in fact it is getting worse. Similarly, the occurrence of this alarm and respect as part of the procedure then in force, without viewing the possible impact, led the pilots to increase engine thrust (TO.GA) and consequently, further increase the incidence of the aircraft. To this we must add the difference in procedure "IAS Doubtful" in relation to the maneuver called an emergency (Memory Items), indicating that of Air France to respect the alarm drop, while that Airbus does not specify . Thus, considering that for obvious security reasons immediate action must be taken, we ask that a recommendation be issued by the BEA, for one hand, informing the drivers, and secondly, to adapt procedures to remarks above. There is no need to wait for the outcome of a hypothetical group "human factors" to respond only to criteria of common sense. It is also noteworthy that the recommendations of the official investigations are suffering from any lead time, which seems inconsistent with the concept of reactivity inherent to aviation safety. In view of these events to the bias displayed, it is essential that the Association obtain a favorable response to his request through the courts to get all the data flight recorder. Finally, we strongly condemn this sad episode that definitely casts discredit on the technical investigation and generates an unprecedented crisis of confidence towards the authorities investigated. The haste with which such authorities and officials have accused the pilots without any prior thought had alerted our suspicion. We now have confirmation that the statements issued by the authority of the BEA were not only premature, lacking objectivity, biased and very oriented toward the defense of Airbus. This is totally improper and unacceptable. The victims of 447 do not deserve such an insult. Families of victims denounced a scandal, which violates their rights to truth ... Association for Solidarity & Mutual AF 447 President Robert Soulas |
Originally Posted by GerardC
(Post 6616699)
Originally posted by "Dozy" With respect, all the sequence between 2:12-20 and 2:13-00 is a succession of nose down inputs followed by stall warning activations followed by nose up inputs (in reaction to the alarm ?).
2:12:28 - Stick *back* (between 8 and 16 degrees) 2:12:35 - Stick *forward* (16 degrees, this is the only correlation at a potentially recoverable altitude) 2:12:40-2:12:45 - Stick moves from *back* (between -4 and -8 degrees) at onset, through *neutral* to *forward* (The stall warning actually *stops* with the stick approx 4 degrees forward - correct behaviour!) 2:12:48-2:12:55 - Stick is *back* at onset (approx -12 degrees) and stall warning *stops* as stick moves from *neutral* to *forward* (approx 4 degrees), again apparently correct behaviour. @ross_M : I'd recommend slogging through the threads to get yourself up to speed, but for reference, when airspeed becomes unreliable for more than a set period of time (25 seconds I think?) -> ADR DISAGREE mode -> ALTERNATE 2 LATCHED (which means Normal Law is out-of-bounds for the duration of the flight). @jcj - spoken like a true weaselly lawyer, going for the deepest pockets. Airbus have already come in for criticism (and will be expected to share in the secondary causes at least) due to the pitot tube issues, and what the press are reporting as "blaming the pilots" is in fact explicit criticism of Air France and the industry in general. I think a new phrase should be coined for using the press to instill doubt in the public mind - "Doing an Asseline". @RWA (below - sorry, don't want to spam the thread!) - It looks to me like they're just covering all bases, as according to the report, the A/P did indeed click off when ADR DISAGREE was detected, and Alternate 2 was indeed latched. It's possible that they discovered in the simulator testing that it was nevertheless possible to re-engage the A/P if the readings were similar but erroneous. |
Any of us who have been involved in 'accident investigations' of any kind will have experienced the way things tend to develop on a 'double track.' It's not usually possible to reveal the 'whole truth' all at once - particularly in cases like this, where so many issues remain unresolved. But the 'lower orders' - in government, among the manufacturers, and in the airlines - will always make every effort (though quietly) to reduce the likelihood of anything like this happening again.
In this connection I find this article interesting:- "Europe's safety authority is to order Airbus A330 and A340 operators to upgrade flight-control computer software to prevent autopilot engagement should airspeeds become unreliable. "Autopilot and auto-thrust on the types will automatically disconnect, and the aircraft will revert to alternate law, in cases where significant differences emerge between the airspeed sources. "This condition can arise if, for example, the pitot system becomes contaminated with ice. "Previously the European Aviation Safety Agency warned that, under such circumstances, it was possible for two airspeed sources to show similar - but nevertheless erroneous - data. "This would permit the crew to re-engage the autopilot while the airspeed data was unsound, potentially resulting in the autopilot transmitting unexpected commands to the flight-control system - such as an abrupt pitch-up. "EASA had cautioned pilots, in a December 2010 directive, to resist re-engaging the autopilot until they had carried out a cross-check of speed indications to ensure that the airspeed data was reliable. "Since that directive was issued, new primary flight-control computer software has been developed which, EASA states, will "inhibit autopilot engagement under unreliable airspeed conditions"." A330/340 change to inhibit autopilot if airspeed unreliable As an additional contribution to the debate, a mate of mine with aviation connections (in Indonesia) just sent me this - which appears to be a first, unofficial, English translation of the AF447 FDR content combined with the CVR transcript. I can't vouch for its authenticity - except that, as far as my knowledge of French goes, the words seem largely to correspond with the French transcript already published. Only thing is, the link misbehaves - people may need to 'zoom in' to about 400% to be able to read the text:- http://www.globalsim.web.id/publicse...uly2011v10.jpg |
Hi,
"EASA had cautioned pilots, in a December 2010 directive, to resist re-engaging the autopilot until they had carried out a cross-check of speed indications to ensure that the airspeed data was reliable. If a software program is able to declare invalid airspeeds and warn the crew (and disengaging the AP) I suppose it's also possible to have the reverse (warn the crew of valid airspeeds and engage again the AP) Logic ? |
jcjeant
Please read my post above. I thank you for your perseverence, and your scepticism of BEA and the commercial principes. The TRUTH is always in the middle. (Well almost always). |
Simmers site. Must be fake.
|
LONEWOLF_50
I dont know if you are right about the sound of stall inside a stall. All Airbus says on the O. Manual is: WHEN STALL WARNING STOPS PILOT MAY INCREASE BACK PRESS AGAIN IN ORTHER TO RECOVER TRAJECTORY. I dont for you, but seems To me that if it works as you say Anywhere in the Operations Manual should be a Caution warning that at high AOA stall warning stops. BUT IT DOESNT. Thanks for tour answer. Is good To learn from others and To share thoughts. Good flights. |
Originally Posted by Kalium Chloride
The real kicker, I suspect, is the timing of the captain's re-entry to the cockpit - almost exactly at the point where the continuous stall alarm switched off. I wonder what he would have done if he'd heard nearly a minute's worth of stall warning.
Originally Posted by Mimpe
The rest was history, as the situation required immediatre transfer of control to PNF, whose spatial orientation and understanding of the situation appears clearly superior throughout. No time for egalitarian social norms
I think Takata and others suggested that PF was PIC so the left seat FO could not take over in such a manner. It has been suggested that he might have liked to based on wording and dual input. When CAP returned to FD there was little time/benefit for seat change. |
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