AF447
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RGB - that piece that washed up in Guyana was quite apparently a chunk of a launch vehicle not an aircraft. Another reader here provided links to pictures of that piece in its original location. That pretty much close the case for most people here.
JD-EE
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JD-EE and Matelo,
Understood. Then I have to question why the piece of "debris" is on its way to France?????? I would have imagined that the AF447 crash investigators would have been all over this piece of whatever-it-is shortly after its discovery. Would they not have gone to Guyana to examine it? And, if so, wouldn't they have known pretty much with certainty that it is, or is not, a piece of AF447?
It just seems odd that the debris, from whatever it is, was loaded onto a ship headed for France. On the other hand, if it is a piece of an Adriane craft I suppose they wouldn't mind having that back either.
Understood. Then I have to question why the piece of "debris" is on its way to France?????? I would have imagined that the AF447 crash investigators would have been all over this piece of whatever-it-is shortly after its discovery. Would they not have gone to Guyana to examine it? And, if so, wouldn't they have known pretty much with certainty that it is, or is not, a piece of AF447?
It just seems odd that the debris, from whatever it is, was loaded onto a ship headed for France. On the other hand, if it is a piece of an Adriane craft I suppose they wouldn't mind having that back either.
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Machinbird, I suspect the entire sensor system on aircraft needs to be rethought from 100 year old technology such as tubes that transmit pressure data from the pitot tube location to the computers.
Suppose you migrate to "smart sensors". Things like PIC chips are little more than the cost of their sand these days. The pressure sensor could be built into the pitot assembly with no long tubes to collect crud. The sensor data could be massaged through a calibration table custom to at least the probe design if not the probe itself and then transmitted digitally to the newer ADIRU equivalents. Such a concept would allow for multiple sensors and multiple types of sensors for the same data in the hope that when one type of sensor for a given data item suffered accuracy problems due to ambient conditions the alternate type would not.
In the 1980s it made sense to run tubing. In this century it makes sense to run wire or fiber and accept the degraded inaccuracies. (Double negative intended for the sake of sarcasm.)
JD-EE
Suppose you migrate to "smart sensors". Things like PIC chips are little more than the cost of their sand these days. The pressure sensor could be built into the pitot assembly with no long tubes to collect crud. The sensor data could be massaged through a calibration table custom to at least the probe design if not the probe itself and then transmitted digitally to the newer ADIRU equivalents. Such a concept would allow for multiple sensors and multiple types of sensors for the same data in the hope that when one type of sensor for a given data item suffered accuracy problems due to ambient conditions the alternate type would not.
In the 1980s it made sense to run tubing. In this century it makes sense to run wire or fiber and accept the degraded inaccuracies. (Double negative intended for the sake of sarcasm.)
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Hi,
Eurocockpit - Accueil
Use at your own risk any translator
Bye.
publié le 30 juillet 2009 à 15:53 par EuroCockpit.
Passée relativement inaperçue à l’époque où elle a été rédigée, la note d’information de l’EASA (Agence de sécurité aérienne européenne) du 9 juin 2009
http://www.eurocockpit.com/docs/EASA_SIB_2009-17_1.pdf
sur les problèmes anémométriques mérite un petit arrêt sur image, et un décryptage a posteriori puisque l'on dispose à présent des grandes lignes de la stratégie du BEA qui a décidé - ou qui s’est fait imposer - qu’il convenait de charger l’équipage, voire s’il le faut quelques étages de la compagnie, pour protéger les intérêts économiques européens prioritaires. Et surtout ne jamais dire ou laisser dire - même si c'est désormais un secret de polichinelle - que les sondes Pitot pourraient être à l’origine de la situation inextricable dans laquelle s’est retrouvé l’équipage, entraînant une perte de contrôle de l’appareil.
L’EASA a donc pris la sage précaution de se tenir à distance de ce "service commandé", en rappelant que les problèmes anémométriques doivent être traités par les opérateurs en appliquant les procédures prévues par le constructeur, en commençant par la mise en oeuvre des procédures «memory items», ces actions que l'équipage doit immédiatement effectuer de mémoire sans consulter préalablement aucune check-list.
Un gros tacle pour Air France, qui - on le rappelle - dispose d’une documentation interne (visée par la DGAC) qui ne dit pas la même chose que celle du constructeur (concernant le respect des alarmes décrochage). Une procédure qui, en effet, demande aux pilotes de croire et de réagir immédiatement de mémoire à toute alarme décrochage, alors que cette demande n'existe pas dans les "memory items" du constructeur... Une procédure qui figure toujours dans la documentation officielle d'Air France mais dont une note de service interne a spécifiquement interdit qu'elle soit appliquée en pareil cas par les pilotes (sic), ceci 4 jours - par hasard bien sur - après le crash (note du 5 juin 2009)...
En substance, l’EASA - avant l’heure - a rédigé la page 70 du rapport du BEA qui met silencieusement en lumière ces différences de procédures. L’Europe et le BEA désignent donc Air France et ses équipages, et l’avion peut voler tranquillement. Avec ou sans vitesse indiquée, puisqu’on vous dit que dans tous les cas, il n’y a qu'à faire comme si tout fonctionnait à merveille.
Et de toutes façons, il suffit de piloter au moins aussi bien que les concierges d'Airbus et d’appliquer la bonne vieille méthode «assiette puissance» pour s’en sortir. Au besoin, on peut aussi appeler Monsieur Feldzer - le découvreur d'ouragan - pour connaître l'épaisseur du nuage, bien que cette procédure soit réservée aux imbéciles qui ne savent pas se servir de leurs radars.
Tout ceci, c’était sans compter le nouvel incident survenu le 13 juillet sur A320 avec des nouvelles sondes Thales «BA», incident sur lequel nous reviendrons avec tous les détails nécessaires. C'est la panique dans tous les rayons du bazar et nous aurons aussi l'occasion d'y revenir. Au passage, on note que le réalisme économique du SNPL lui a fait faire marche arrière sur sa demande de changement des sondes Thales par des Goodrich n’ayant jamais connu d’incident : la perte des données de vitesse n’a duré que 7 secondes, alors c’est acceptable. Sans que l’on sache au-delà de quel laps de temps sans indication de vitesse Monsieur Derivry considère que la sécurité des vols est engagée. Plus de sept secondes, mais combien… Huit secondes ? Vingt ? Une minute ? Jusqu’au crash ?
En attendant, Air France a pris une disposition courageuse qui montre à quel point ce problème de sondes Pitot est considéré avec attention, même si Monsieur Gourgeon a maintes fois indiqué que le crash de l'AF447 n’avait rien à voir avec tout cela, ne pouvait pas être lié à cela et avait l'interdiction définitive de venir de cela. En effet, pour bien montrer à quel point il n’y avait - il n'y a et il n'y aura - jamais eu aucun problème de sondes, Air France a décidé de… supprimer tous les ASR (rapports d'incident) s’y rapportant des bases de données internes de la Compagnie.
Sur les 9 incidents rapportés, il n’y a plus aucune trace nulle part d’aucun rapport d'incident d’aucun commandant de bord...
Quelques archives dans la revue «Survol» - parce qu'on n'a pas pu rappeler tous les numéros pour les mettre discrètement au pilon - mais le reste a disparu.
Pour la plus grande joie du BEA qui, finalement, a choisi le camp de l’autre copain de promo 1965… La vie impose parfois des choix cruels, mais Airbus l’a emporté en précisant aujourd’hui, par la voix de Tom Enders, que le constructeur serait prêt à «donner» au BEA une somme de 12 à 20 millions d’euros (une broutille comparée aux chiffres avancés par ailleurs sur les délits d’initiés) pour «étendre les recherches». Imaginerait-on un jour que Boeing puisse financer le NTSB ?
Mais le BEA est sage, même si son «choix» a été facilité depuis qu'il se murmure, dans les "milieux autorisés" et depuis quelques semaines, que la décision irrévocable de trouver rapidement un successeur à Monsieur Gourgeon a déjà été prise au plus haut niveau de l'Etat, la discussion ne portant désormais plus que sur le sort des sous-fifres...
Passée relativement inaperçue à l’époque où elle a été rédigée, la note d’information de l’EASA (Agence de sécurité aérienne européenne) du 9 juin 2009
http://www.eurocockpit.com/docs/EASA_SIB_2009-17_1.pdf
sur les problèmes anémométriques mérite un petit arrêt sur image, et un décryptage a posteriori puisque l'on dispose à présent des grandes lignes de la stratégie du BEA qui a décidé - ou qui s’est fait imposer - qu’il convenait de charger l’équipage, voire s’il le faut quelques étages de la compagnie, pour protéger les intérêts économiques européens prioritaires. Et surtout ne jamais dire ou laisser dire - même si c'est désormais un secret de polichinelle - que les sondes Pitot pourraient être à l’origine de la situation inextricable dans laquelle s’est retrouvé l’équipage, entraînant une perte de contrôle de l’appareil.
L’EASA a donc pris la sage précaution de se tenir à distance de ce "service commandé", en rappelant que les problèmes anémométriques doivent être traités par les opérateurs en appliquant les procédures prévues par le constructeur, en commençant par la mise en oeuvre des procédures «memory items», ces actions que l'équipage doit immédiatement effectuer de mémoire sans consulter préalablement aucune check-list.
Un gros tacle pour Air France, qui - on le rappelle - dispose d’une documentation interne (visée par la DGAC) qui ne dit pas la même chose que celle du constructeur (concernant le respect des alarmes décrochage). Une procédure qui, en effet, demande aux pilotes de croire et de réagir immédiatement de mémoire à toute alarme décrochage, alors que cette demande n'existe pas dans les "memory items" du constructeur... Une procédure qui figure toujours dans la documentation officielle d'Air France mais dont une note de service interne a spécifiquement interdit qu'elle soit appliquée en pareil cas par les pilotes (sic), ceci 4 jours - par hasard bien sur - après le crash (note du 5 juin 2009)...
En substance, l’EASA - avant l’heure - a rédigé la page 70 du rapport du BEA qui met silencieusement en lumière ces différences de procédures. L’Europe et le BEA désignent donc Air France et ses équipages, et l’avion peut voler tranquillement. Avec ou sans vitesse indiquée, puisqu’on vous dit que dans tous les cas, il n’y a qu'à faire comme si tout fonctionnait à merveille.
Et de toutes façons, il suffit de piloter au moins aussi bien que les concierges d'Airbus et d’appliquer la bonne vieille méthode «assiette puissance» pour s’en sortir. Au besoin, on peut aussi appeler Monsieur Feldzer - le découvreur d'ouragan - pour connaître l'épaisseur du nuage, bien que cette procédure soit réservée aux imbéciles qui ne savent pas se servir de leurs radars.
Tout ceci, c’était sans compter le nouvel incident survenu le 13 juillet sur A320 avec des nouvelles sondes Thales «BA», incident sur lequel nous reviendrons avec tous les détails nécessaires. C'est la panique dans tous les rayons du bazar et nous aurons aussi l'occasion d'y revenir. Au passage, on note que le réalisme économique du SNPL lui a fait faire marche arrière sur sa demande de changement des sondes Thales par des Goodrich n’ayant jamais connu d’incident : la perte des données de vitesse n’a duré que 7 secondes, alors c’est acceptable. Sans que l’on sache au-delà de quel laps de temps sans indication de vitesse Monsieur Derivry considère que la sécurité des vols est engagée. Plus de sept secondes, mais combien… Huit secondes ? Vingt ? Une minute ? Jusqu’au crash ?
En attendant, Air France a pris une disposition courageuse qui montre à quel point ce problème de sondes Pitot est considéré avec attention, même si Monsieur Gourgeon a maintes fois indiqué que le crash de l'AF447 n’avait rien à voir avec tout cela, ne pouvait pas être lié à cela et avait l'interdiction définitive de venir de cela. En effet, pour bien montrer à quel point il n’y avait - il n'y a et il n'y aura - jamais eu aucun problème de sondes, Air France a décidé de… supprimer tous les ASR (rapports d'incident) s’y rapportant des bases de données internes de la Compagnie.
Sur les 9 incidents rapportés, il n’y a plus aucune trace nulle part d’aucun rapport d'incident d’aucun commandant de bord...
Quelques archives dans la revue «Survol» - parce qu'on n'a pas pu rappeler tous les numéros pour les mettre discrètement au pilon - mais le reste a disparu.
Pour la plus grande joie du BEA qui, finalement, a choisi le camp de l’autre copain de promo 1965… La vie impose parfois des choix cruels, mais Airbus l’a emporté en précisant aujourd’hui, par la voix de Tom Enders, que le constructeur serait prêt à «donner» au BEA une somme de 12 à 20 millions d’euros (une broutille comparée aux chiffres avancés par ailleurs sur les délits d’initiés) pour «étendre les recherches». Imaginerait-on un jour que Boeing puisse financer le NTSB ?
Mais le BEA est sage, même si son «choix» a été facilité depuis qu'il se murmure, dans les "milieux autorisés" et depuis quelques semaines, que la décision irrévocable de trouver rapidement un successeur à Monsieur Gourgeon a déjà été prise au plus haut niveau de l'Etat, la discussion ne portant désormais plus que sur le sort des sous-fifres...
Use at your own risk any translator
Bye.
Suppose you migrate to "smart sensors". Things like PIC chips are little more than the cost of their sand these days. The pressure sensor could be built into the pitot assembly with no long tubes to collect crud. The sensor data could be massaged through a calibration table custom to at least the probe design if not the probe itself and then transmitted digitally to the newer ADIRU equivalents. Such a concept would allow for multiple sensors and multiple types of sensors for the same data in the hope that when one type of sensor for a given data item suffered accuracy problems due to ambient conditions the alternate type would not.
The probe issue still nags and nags - Most of the probes i've seen in the past have heaters but no temperature sensing and looking at the data sheets for the two AI fittings mentioned earlier, it looks like they are similar. Why is this of interest ? . Without sensing, it's not possible to have closed loop probe heat control. This means that the probes are getting full power all the time they are switched on. With 300 to 500 watts input typical, it wouldn't surprise me if the probes get almost cherry red hot on the ground, which can't be good for probe life. With a temperature sensor and a decent controller + enough heat capacity, it should be no problem to maintain temperature at optimum levels irespective of load and would also eliminate ground overheating. Otoh, perhaps they use a resistance element with a positive tempco, but it's still a bit primitive.
Iirc, simple 3 term pid controllers are a first year electronics undergrad subject and have been used in industry for decades...
Chris
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AB probably already have the equivalent software to provide a Pseudo Air Speed (PAS). The software will provide PAS in every a/c configuration, but like everything else in FBW systems it too needs some external references such as air pressure, OAT and altitude. The a/c configuration clean/unclean, CG, weight, thrust, AoA, pitch, bank angle, spoilers, slats and gear etc., down to and including ground effect should provide a IAS/TAS equivalent to that provided to the ADIRUs from correctly operating Pitots.
Lets face it, the SIM algorithms operate using the same principle.
mm43
Lets face it, the SIM algorithms operate using the same principle.
mm43
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The EASA stance
The EASA claims:
"The Aircraft Flight and/or Flight Crew Operating Manuals include procedures for unreliable airspeed indication (Air data system misleading information) and these should be well known by flight crews. Correct application of these procedures by flight crews may be crucial for assuring the safety of the aircraft when such Pitot-static malfunctions occur."
sure, but
1) the Air Caraïbe crew got out without problem by not applying entirely (the stall alarm part) these crucial procedures (and some of its parts being not implementable due to time constraints)
2) how can a crew rely on any procedure when the safety of the plane is immediately impacted by a (false) stall alarm and that the pilot has to take an immediate decision in a context of unreliable airspeeds ? (the AF Paris Antananarivo case)
3) the word "crucial" sounds weird when a month ago Pitot problems posed no safety problems.
I don't understand why the high probability of false stall alarms in this context is never mentioned by the authorities (always mentioning the airspeed loss & pich/thrust procedures).
now, the EASA says it is considering a mandatory change of at least two of the three Pitot probes, so as to have at least two Goodrich probes:
http://www.lexpress.fr/actualites/2/l-ue-voudrait-interdire-un-type-de-capteur-sur-l-airbus-a330_777849.html
I don't even understand why one suspect probe is tolerated on board
Oh yes, the suspect probe only failed 6 sec. between Paris and Rome a couple of weeks ago. But...How long since they had been introduced ? There should not be any compromise to the safety (all the more if it is about 2000$ per plane).
Jeff, pissed off, and intrigued
PS) Has the NTSB produced any report on the Northwest case of Pitot freezing ?
"The Aircraft Flight and/or Flight Crew Operating Manuals include procedures for unreliable airspeed indication (Air data system misleading information) and these should be well known by flight crews. Correct application of these procedures by flight crews may be crucial for assuring the safety of the aircraft when such Pitot-static malfunctions occur."
sure, but
1) the Air Caraïbe crew got out without problem by not applying entirely (the stall alarm part) these crucial procedures (and some of its parts being not implementable due to time constraints)
2) how can a crew rely on any procedure when the safety of the plane is immediately impacted by a (false) stall alarm and that the pilot has to take an immediate decision in a context of unreliable airspeeds ? (the AF Paris Antananarivo case)
3) the word "crucial" sounds weird when a month ago Pitot problems posed no safety problems.
I don't understand why the high probability of false stall alarms in this context is never mentioned by the authorities (always mentioning the airspeed loss & pich/thrust procedures).
now, the EASA says it is considering a mandatory change of at least two of the three Pitot probes, so as to have at least two Goodrich probes:
http://www.lexpress.fr/actualites/2/l-ue-voudrait-interdire-un-type-de-capteur-sur-l-airbus-a330_777849.html
I don't even understand why one suspect probe is tolerated on board
Oh yes, the suspect probe only failed 6 sec. between Paris and Rome a couple of weeks ago. But...How long since they had been introduced ? There should not be any compromise to the safety (all the more if it is about 2000$ per plane).Jeff, pissed off, and intrigued
PS) Has the NTSB produced any report on the Northwest case of Pitot freezing ?
Last edited by Hyperveloce; 30th Jul 2009 at 22:19.
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syseng68k,
The jet has 3 Probe Heat Controllers that use various logic to vary temperature, depending on conditions -
automatically when at least one engine is running, or in flight
manually by switching ON the PROBE/WINDOW HEAT pushbutton.
On the ground, TAT probes are not heated and pitot heating operates at low level (normal power in flight by automatic changeover).
The jet has 3 Probe Heat Controllers that use various logic to vary temperature, depending on conditions -
automatically when at least one engine is running, or in flight
manually by switching ON the PROBE/WINDOW HEAT pushbutton.
On the ground, TAT probes are not heated and pitot heating operates at low level (normal power in flight by automatic changeover).
Per Ardua ad Astraeus
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infrequentflyer789- it was actually a serious question which you have unfortunately misinterpreted.
As far as I am aware, we have a few Boeing accidents caused by blocked pressure sensors - recently an Astraeus operated 757, a bug in the tubes. Yours a wasp in the tubes. Another - ?Peru? by taped over statics. Others I'm sure, I have forgotten. Do we have any events similar to what we are seeing here on other types? The question remains - is this a failure with a common interface link?
As far as I am aware, we have a few Boeing accidents caused by blocked pressure sensors - recently an Astraeus operated 757, a bug in the tubes. Yours a wasp in the tubes. Another - ?Peru? by taped over statics. Others I'm sure, I have forgotten. Do we have any events similar to what we are seeing here on other types? The question remains - is this a failure with a common interface link?
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From Reuters 30JUN09
"Airbus recommends speed sensor switch after crash"
UPDATE 1-Airbus recommends speed sensor switch after crash | Reuters
UPDATE 1-Airbus recommends speed sensor switch after crash | Reuters
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Hi,
That's a very strange solution .. seem's a smoke screen .......
So .. if other Pitot case problems in the future on such equipped planes (mixed Pitot brands) it will be :
"It's not my Pitot faulty .. it's the other brand" ..
Bye.
now, the EASA says it is considering a mandatory change of at least two of the three Pitot probes, so as to have at least two Goodrich probes:
So .. if other Pitot case problems in the future on such equipped planes (mixed Pitot brands) it will be :
"It's not my Pitot faulty .. it's the other brand" ..
Bye.
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rgbrock1 said
France is in charge of the technical investigation being the State of registration of the aircraft.
From what I have understood from the France2 or France3 reports, the debris that have arrived in France were those found by the Brazilian Navy. About 650 pieces. In August about 450 new ones should arrived. These new debris should be the ones retrieved by the French Navy or vessels. Because nobody in France speaks of any debris found nearby Guyana (Kourou space center), I think that the futur debris will come from the crash area. The French Guyana doesn't have the capacity to receive, handle, analyse the debris and conduct such an enquiry. So everything is sent at Toulouse at the Centre d'Essais Aéronautiques.
The BEA Has published the 30th a communiqué:
Press release 30 July 2009
Flight AF 447 on 1st June 2009
A 330 – 200, registered F-GZCP
The Ifremer oceanographic ship “Pourquoi pas?” is currently on site in the area for the second phase of the search for the flight recorders from AF 447. Work to survey the ocean floor has begun in the area considered to be the most likely, with the aid of a side-scan sonar device and the Victor 6000 ROV and Nautile submarine. The flight recorders’ locator beacons having now ceased transmitting, the next step is to identify the place where the airplane wreckage is located, then to search for the recorders.
The BEA recognizes Airbus’ commitment to participate financially in a continuation of the search if a third phase, over a wider area, appears to be necessary.
About the Ifremer, and for the anedocte, if you go here:
Localisation des navires océanographiques de l'IFREMER
you will notice that the "Pourquoi pas?" is shown at Cabo Verde and she has not moved from there since the beginning of June...
Understood. Then I have to question why the piece of "debris" is on its way to France?????? I would have imagined that the AF447 crash investigators would have been all over this piece of whatever-it-is shortly after its discovery. Would they not have gone to Guyana to examine it? And, if so, wouldn't they have known pretty much with certainty that it is, or is not, a piece of AF447?
It just seems odd that the debris, from whatever it is, was loaded onto a ship headed for France. On the other hand, if it is a piece of an Adriane craft I suppose they wouldn't mind having that back either.
It just seems odd that the debris, from whatever it is, was loaded onto a ship headed for France. On the other hand, if it is a piece of an Adriane craft I suppose they wouldn't mind having that back either.
From what I have understood from the France2 or France3 reports, the debris that have arrived in France were those found by the Brazilian Navy. About 650 pieces. In August about 450 new ones should arrived. These new debris should be the ones retrieved by the French Navy or vessels. Because nobody in France speaks of any debris found nearby Guyana (Kourou space center), I think that the futur debris will come from the crash area. The French Guyana doesn't have the capacity to receive, handle, analyse the debris and conduct such an enquiry. So everything is sent at Toulouse at the Centre d'Essais Aéronautiques.
The BEA Has published the 30th a communiqué:
Press release 30 July 2009
Flight AF 447 on 1st June 2009
A 330 – 200, registered F-GZCP
The Ifremer oceanographic ship “Pourquoi pas?” is currently on site in the area for the second phase of the search for the flight recorders from AF 447. Work to survey the ocean floor has begun in the area considered to be the most likely, with the aid of a side-scan sonar device and the Victor 6000 ROV and Nautile submarine. The flight recorders’ locator beacons having now ceased transmitting, the next step is to identify the place where the airplane wreckage is located, then to search for the recorders.
The BEA recognizes Airbus’ commitment to participate financially in a continuation of the search if a third phase, over a wider area, appears to be necessary.
About the Ifremer, and for the anedocte, if you go here:
Localisation des navires océanographiques de l'IFREMER
you will notice that the "Pourquoi pas?" is shown at Cabo Verde and she has not moved from there since the beginning of June...
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"Not the only cause".....? The first 'cause' without which the chain could not be continued is what's known as the 'procuring cause'. The authorities including Airbus and Air France are playing with language, in my opinion.
Technically they are not incorrect, but they are suggesting that there may have been more than one cause. There can be a combination of events that exacerbate or accelerate outcome, but the pitots are in the 'hot' seat for now. Is it possible for the crash to have happened if the pitots had functioned properly? The answer is yes, but demands accepting coincidental events at long odds.
AB is calling for replacement of Thales (both types? but only two instead of all three). Two questions.
1. Where was their 'request' when the pilots 'demanded' it?
2. Why only two? Not all three? Taking a chance, aren't they?
If the remaining Thales fails, and...........
Since the sampling system uses pairs, only one good pair is left, G-G.
This is a singly redundant system.
Technically they are not incorrect, but they are suggesting that there may have been more than one cause. There can be a combination of events that exacerbate or accelerate outcome, but the pitots are in the 'hot' seat for now. Is it possible for the crash to have happened if the pitots had functioned properly? The answer is yes, but demands accepting coincidental events at long odds.
AB is calling for replacement of Thales (both types? but only two instead of all three). Two questions.
1. Where was their 'request' when the pilots 'demanded' it?
2. Why only two? Not all three? Taking a chance, aren't they?
If the remaining Thales fails, and...........
Since the sampling system uses pairs, only one good pair is left, G-G.
This is a singly redundant system.
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Will,
Its money. I imagine most Thales operators have just upgraded any existing AA to AB probes. I am sure that No 1 and No 3 will be changed and it will be a good test bed, to see if the F/O's air data goes haywire, to see if the Capt's and Stby are operating correctly.
It will also be about supply. If the figures are correct, then 400 new probes are going to be needed. I don't know if the ADM's are generic or not. If not, then 400 of them too.
Its money. I imagine most Thales operators have just upgraded any existing AA to AB probes. I am sure that No 1 and No 3 will be changed and it will be a good test bed, to see if the F/O's air data goes haywire, to see if the Capt's and Stby are operating correctly.
It will also be about supply. If the figures are correct, then 400 new probes are going to be needed. I don't know if the ADM's are generic or not. If not, then 400 of them too.
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About the Ifremer, and for the anedocte, if you go here:
Localisation des navires océanographiques de l'IFREMER
you will notice that the "Pourquoi pas?" is shown at Cabo Verde and she has not moved from there since the beginning of June...
Localisation des navires océanographiques de l'IFREMER
you will notice that the "Pourquoi pas?" is shown at Cabo Verde and she has not moved from there since the beginning of June...
No position during the search period
... you won't know it if I'm getting or have been stationary ...
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AOA just Along for the Ride
AOA is the best indicator of stall. Why airliners haven't used it as primary stall warning just puzzles me. Stalling airspeed varies with bank angle and wing loading, but AOA is just that, Angle of Attack, the exact meaurement of stall margin, regardless of bank angle and wing loading.
The stall warning detector on the basic Cessna 150 is a binary AOA device, independent of pitot pressure. Why did the airliners give up that simple redundancy?
GB
The stall warning detector on the basic Cessna 150 is a binary AOA device, independent of pitot pressure. Why did the airliners give up that simple redundancy?
GB
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GB, this AoA based stall detection of the Cessna looks like the AoA law (alpha prot) on Airbuses. But to get an aerodynamical margin, don't we have to compare the AoA to a threshold/a max AoA ? (what is done in the alpha prot). Shouldn't this max AoA depend on the airspeed/altitude ? (Pitot/static)
Jeff
Jeff
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The probe issue still nags and nags - Most of the probes i've seen in the past have heaters but no temperature sensing
As you doubtless know, resistance wire has a positive temp coefficient, and has a higher resistance as it heats up. This within reason makes the heater elements self-regulating, as the current (and thus heat input) will decrease as the element heats up.
But a smart heater controller can measure the current flow and voltage to the heater, and thus determine the resistance. This, in turn, is a measurement of the temperature of the element. It isn't as sensitive as a thermocouple, but it can be pretty good -- especially since the main goals are to prevent the element burning out from overheat, while providing enough current to keep it above some specified temperature.
A better design would probably divide the heater element into 3 or 4 sections, and possibly add a few thermistors, and thus be able to keep a relatively constant temperature (or any other desired heat profile) on the sensor. As it is, the sensor will be at varying temperatures along the single heater winding, depending on the heat load/loss for that section of heater element.
“ AOA is the best indicator of stall. Why airliners haven't used it as primary stall warning just puzzles me. # 4038
Many (most) airliners use AOA for stall warning and stall identification.
The A330 had AOA and in some modes of operation used it for stall alerting; in this instance it appears that the method of routing AOA information via the ADC was a possible problem.
Re: “EASA says it is considering a mandatory change of at least two of the three Pitot probes …”
EASA’s problem appears to be that having already known of the deficiency ( Instrument External Probes), and presumably agreed that crew procedures in the event of unreliable airspeed would be sufficient, this accident may have proved otherwise.
Disregarding hindsight, I wonder how many readers here would have accepted that attitude and power were sufficient for short duration flight without airspeed … of course excepting when in adverse convective weather.
HF in regulation; thinking of all of the alternative scenarios, context, and a judgment call … no blame just a better understanding
Many (most) airliners use AOA for stall warning and stall identification.
The A330 had AOA and in some modes of operation used it for stall alerting; in this instance it appears that the method of routing AOA information via the ADC was a possible problem.
Re: “EASA says it is considering a mandatory change of at least two of the three Pitot probes …”
EASA’s problem appears to be that having already known of the deficiency ( Instrument External Probes), and presumably agreed that crew procedures in the event of unreliable airspeed would be sufficient, this accident may have proved otherwise.
Disregarding hindsight, I wonder how many readers here would have accepted that attitude and power were sufficient for short duration flight without airspeed … of course excepting when in adverse convective weather.
HF in regulation; thinking of all of the alternative scenarios, context, and a judgment call … no blame just a better understanding