AF 447 Thread No. 8
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
The 757 Cali crash changed our memory items to stow the speed brakes but it probably wouldn't had made any difference anyway. I was flying to Panama City that night and there was no moon so when they screwed up and headed east through the hills to Bogata because both outer markers had the same designater they could not see the terrain. My FO questioned our visual that night overflying the airport at 5,000 ft approaching over the Pacific and said all we have to clear now are sailboat masts.
I was offered the same approach straight in as them and out of courtesy declined it because of the people we lost in that crash. It isn't a hard approach but doing the ILS from the south side seemed like the thing to do after that awful crash.
I was offered the same approach straight in as them and out of courtesy declined it because of the people we lost in that crash. It isn't a hard approach but doing the ILS from the south side seemed like the thing to do after that awful crash.
Join Date: Jun 2009
Location: NNW of Antipodes
Age: 81
Posts: 1,330
Received 0 Likes
on
0 Posts
aguadalte;
Perhaps you would like to discuss anything the TRE brought to your attention regarding trim control when other than in Normal Law.
You must have missed a fairly intense discussion that took place in AF447 Thread No.6, where we were privileged to have some well thought-out input from an experienced aerodynamics engineer.
To directly answer your question, the DFDR traces indicate that even when stalled and with low IAS, any SS ND resulted in the appropriate response.
Yes...but the question is: did they have enough pitch command to put the nose down when the THS reached more than 13º nose up?
You must have missed a fairly intense discussion that took place in AF447 Thread No.6, where we were privileged to have some well thought-out input from an experienced aerodynamics engineer.
To directly answer your question, the DFDR traces indicate that even when stalled and with low IAS, any SS ND resulted in the appropriate response.
Last edited by mm43; 13th May 2012 at 03:02.
A good post and time to reconsider ....
PJ2: @ TurbineD - a fine post, thanks.
Join Date: Jul 2009
Location: France - mostly
Age: 84
Posts: 1,682
Likes: 0
Received 0 Likes
on
0 Posts
Interesting aspect of the AF A340 zoom climb is that alphamax is exceeded in normal law.
Last edited by HazelNuts39; 13th May 2012 at 10:46. Reason: SS not neutral
Join Date: Oct 2009
Location: UK
Posts: 1,270
Likes: 0
Received 0 Likes
on
0 Posts
Hi HazelNuts39,
Presumably alpha is measured real time and the airspeed can reduce if delta g is reduced during the apogee. It will take some time for the attitude of the aircraft to change in response to the new alpha measured at 1g, when the speed was so far back.
Some "amazing" recommendations by BEA including:
"The BEA released another safety recommendation to EASA to require the autopilot disconnect aural alarm become continuous until cancelled by human action, reasoning that the A340 cavalry charge by design sounds 1.5 seconds and may therefore be suppressed by a higher priority aural alert. This suppression had contributed to a critical incident, the BEA continued."
Wtfiidn? springs to mind.
Interesting aspect of the AF A340 zoom climb is that alphamax is exceeded in normal law.
Some "amazing" recommendations by BEA including:
"The BEA released another safety recommendation to EASA to require the autopilot disconnect aural alarm become continuous until cancelled by human action, reasoning that the A340 cavalry charge by design sounds 1.5 seconds and may therefore be suppressed by a higher priority aural alert. This suppression had contributed to a critical incident, the BEA continued."
Wtfiidn? springs to mind.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Turbine D -
An excellent post, thanks. However I do have to take issue with one aspect:
This is incorrect. Landing mode was never triggered. (The theory that put this forward was in fact advanced by Asseline's lawyers and repeated in the international press).
What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.
In order to do this he did not simply disarm autothrust, he actually disabled it - by holding down the disarm buttons. This makes A/THR unavailable until reset by ground crew (it was in fact intended to be used if A/THR developed a malfunction), and therefore also inhibits alpha floor protection (which is distinct from alpha protection). In order to expedite descent he chopped the thrust back past the point required for the flypast and the engines spooled down, which is a big no-no on approach as I understand it. The descent was expedited a little too much and they went below 100ft RA shortly after crossing the threshold. Landing mode was not triggered - possibly because the RA never held a stable value long enough to do so.
The photocopied aerodrome map did not show the trees at the end of the grass runway because on the original they were a light grey shade below the threshold of the photocopier - they were spotted as a danger about halfway down the runway and the thrust levers were pushed to the TOGA position shortly afterwards. Unfortunately with the engines spooled down and alpha floor disabled with the autothrust as a result of the expedited descent, they took too long to spool back up, and the only remaining protection was alpha protection, which limits pitch attitude to preserve AoA above stall. This, not landing mode, was the reason the aircraft did not climb when Asseline pulled up - he simply did not have the required thrust or airspeed to do so by the time the aircraft was over the trees.
In this case, had Asseline been able to override the computer completely, the aircraft would have stalled short of the trees, crashed out of control and many more would likely have died* as a result. As such, there's a degree of tragic irony that, had the A320 done as Asseline asked, he may not have survived to publicly rubbish the A320 for not doing as he asked.
[* - EDIT : The three deaths that did occur (tragically including two children) were as a result of smoke inhalation, not impact forces - and the injuries were relatively minor, with a few serious cases involving broken bones. ]
An excellent post, thanks. However I do have to take issue with one aspect:
What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.
In order to do this he did not simply disarm autothrust, he actually disabled it - by holding down the disarm buttons. This makes A/THR unavailable until reset by ground crew (it was in fact intended to be used if A/THR developed a malfunction), and therefore also inhibits alpha floor protection (which is distinct from alpha protection). In order to expedite descent he chopped the thrust back past the point required for the flypast and the engines spooled down, which is a big no-no on approach as I understand it. The descent was expedited a little too much and they went below 100ft RA shortly after crossing the threshold. Landing mode was not triggered - possibly because the RA never held a stable value long enough to do so.
The photocopied aerodrome map did not show the trees at the end of the grass runway because on the original they were a light grey shade below the threshold of the photocopier - they were spotted as a danger about halfway down the runway and the thrust levers were pushed to the TOGA position shortly afterwards. Unfortunately with the engines spooled down and alpha floor disabled with the autothrust as a result of the expedited descent, they took too long to spool back up, and the only remaining protection was alpha protection, which limits pitch attitude to preserve AoA above stall. This, not landing mode, was the reason the aircraft did not climb when Asseline pulled up - he simply did not have the required thrust or airspeed to do so by the time the aircraft was over the trees.
In this case, had Asseline been able to override the computer completely, the aircraft would have stalled short of the trees, crashed out of control and many more would likely have died* as a result. As such, there's a degree of tragic irony that, had the A320 done as Asseline asked, he may not have survived to publicly rubbish the A320 for not doing as he asked.
[* - EDIT : The three deaths that did occur (tragically including two children) were as a result of smoke inhalation, not impact forces - and the injuries were relatively minor, with a few serious cases involving broken bones. ]
Last edited by DozyWannabe; 13th May 2012 at 15:56.
Join Date: Jul 2009
Location: France - mostly
Age: 84
Posts: 1,682
Likes: 0
Received 0 Likes
on
0 Posts
RRR,
The exceedance of Alpha MAX by about 2 degrees during less than 2 seconds occurs in the initial phase of the incident. In the words of BEA (see also the graph):
My translation:
At first a headwind gust (see note 1) causes an overspeed and activates the "OVERSPEED" warning. A few seconds later an upward gust causes an increase of AoA and vertical speed. Then the PNF disconnects the AP and makes a nose-up command during 6 seconds while the PF extends the speedbrakes. At the start of the nose-up command the AoA exceeds Alpha Prot and the High AoA protection is activated. Then, during 2 s, the AoA is briefly less than Alpha Prot, with the SS at neutral, which cancels the protection. The combined effects of turbulence, of the SS command and the extension of the speedbrakes lead to an increase of pitch attitude, vertical speed and altitude. A peak of AoA greater than Alpha Prot activates the High AoA Protection again. The AoA continues to increase and exceeds Alpha MAX, which causes the automatic retraction of the speedbrakes.
Note 1: The numerical simulations show that the turbulence encountered in the occurrence is essentially characterized by a headwind gust of 25 kt, followed a few seconds later by a 35 kt upward gust. A second upward gust of 15 kt occurs about 10 seconds later. The total duration of the turbulence is approximately one minute.
P.S. Somewhat mysterious is the continued pitch up with the SS at neutral. One would like to see the elevator trace for that element of the occurrence. An explanation could be the decreasing vertical speed, possibly resulting from a downward gust, and the control system maintaining 1g.
The exceedance of Alpha MAX by about 2 degrees during less than 2 seconds occurs in the initial phase of the incident. In the words of BEA (see also the graph):
Phase 1 : dans un premier temps, une rafale de vent de face(1) génère une survitesse et l’activation de l’alarme « OVERSPEED ». Quelques secondes plus tard, une rafale ascendante entraîne une augmentation de l’incidence et de la vitesse verticale. Puis, le PNF déconnecte le pilote automatique et donne un ordre à cabrer pendant 6 s tandis que le PF sort les aérofreins. Dès le début de l’ordre à cabrer, l’incidence étant supérieure à Alpha Prot, la protection grande incidence s’active. Puis, pendant 2 s, l’incidence passe brièvement sous Alpha Prot, avec le manche au neutre, ce qui fait sortir de la protection. Les effets conjoints de la turbulence, de l’action au manche et de la sortie des aérofreins entraînent la prise d’assiette, de vitesse verticale et d’altitude. Un pic d’incidence supérieure à Alpha Prot active de nouveau la protection grande incidence. L’incidence continue d’augmenter et dépasse Alpha MAX, ce qui provoque la rentrée automatique des aérofreins.
(1)Des simulations numériques montrent que la turbulence rencontrée lors de l’évènement se caractérise essentiellement par une rafale de face de 25 kt suivie quelques secondes plus tard par une rafale ascendante de 35 kt. Une deuxième rafale ascendante de 15 kt se produit environ 10 secondes plus tard. La durée totale des turbulences est d’environ une minute.
(1)Des simulations numériques montrent que la turbulence rencontrée lors de l’évènement se caractérise essentiellement par une rafale de face de 25 kt suivie quelques secondes plus tard par une rafale ascendante de 35 kt. Une deuxième rafale ascendante de 15 kt se produit environ 10 secondes plus tard. La durée totale des turbulences est d’environ une minute.
At first a headwind gust (see note 1) causes an overspeed and activates the "OVERSPEED" warning. A few seconds later an upward gust causes an increase of AoA and vertical speed. Then the PNF disconnects the AP and makes a nose-up command during 6 seconds while the PF extends the speedbrakes. At the start of the nose-up command the AoA exceeds Alpha Prot and the High AoA protection is activated. Then, during 2 s, the AoA is briefly less than Alpha Prot, with the SS at neutral, which cancels the protection. The combined effects of turbulence, of the SS command and the extension of the speedbrakes lead to an increase of pitch attitude, vertical speed and altitude. A peak of AoA greater than Alpha Prot activates the High AoA Protection again. The AoA continues to increase and exceeds Alpha MAX, which causes the automatic retraction of the speedbrakes.
Note 1: The numerical simulations show that the turbulence encountered in the occurrence is essentially characterized by a headwind gust of 25 kt, followed a few seconds later by a 35 kt upward gust. A second upward gust of 15 kt occurs about 10 seconds later. The total duration of the turbulence is approximately one minute.
P.S. Somewhat mysterious is the continued pitch up with the SS at neutral. One would like to see the elevator trace for that element of the occurrence. An explanation could be the decreasing vertical speed, possibly resulting from a downward gust, and the control system maintaining 1g.
Last edited by HazelNuts39; 14th May 2012 at 08:25. Reason: P.S.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Habsheim
DW
What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.
What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.
They
up big time, i live 10 klicks away. from airbus last pages
Last edited by RetiredF4; 13th May 2012 at 16:44.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
None of the crew believed they had gone that low - all evidence indicates that they didn't realise they were in any danger until they realised they were level with the trees - as such the CVR was routine up until that point, and quickly became a shouting match as they tried to get out of the corner they'd painted themselves into.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
[nitpick]Alpha floor protection, to be precise (the thrust component). Alpha protection, which is a flight control function and affects pitch and bank, remains active at all times in Normal Law IIRC[/nitpick]
As it should have. AF's performance as an entity was well below-par that day.
I've often wondered if Asseline would have had a better case if he had gone after AF rather than Airbus - but I suspect that he would not have had the benefit of union backing had he pursued that line.
The report criticizes planning, coordination and so on.
I've often wondered if Asseline would have had a better case if he had gone after AF rather than Airbus - but I suspect that he would not have had the benefit of union backing had he pursued that line.
Last edited by DozyWannabe; 13th May 2012 at 17:12.
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes
on
0 Posts
Advantages of two SS with no feedback
Hi,
aguadalte
Some time ago you mentioned in an excellent post to CONF iture (*) some points that could clarify an issue:
Why AI (Airbus SAS) introduced the SS?
This issue is being covered in another Thread concerning the "interface". The paper you mention discuss the issue and is a confirmation of some concerns i had previously.
Could you help me to understand why Airbus Industries (Airbus SAS) introduced two separated SS with no feedback in their planes?
There are advantages with this design?
I mentioned my post in the specific thread avoiding to discuss the issue in AF447 thread. I don't consider the interface an issue between A or B. My agenda is on Aviation Safety, during normal conditions and during anomalies.
PS
(*)
aguadalte
Some time ago you mentioned in an excellent post to CONF iture (*) some points that could clarify an issue:
Why AI (Airbus SAS) introduced the SS?
This issue is being covered in another Thread concerning the "interface". The paper you mention discuss the issue and is a confirmation of some concerns i had previously.
Could you help me to understand why Airbus Industries (Airbus SAS) introduced two separated SS with no feedback in their planes?
There are advantages with this design?
I mentioned my post in the specific thread avoiding to discuss the issue in AF447 thread. I don't consider the interface an issue between A or B. My agenda is on Aviation Safety, during normal conditions and during anomalies.
PS
(*)
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
There are advantages with this design?
In the development portion of the design, it occurs of course that separated controls were a new direction. The risks were no doubt delineated, assessed and addressed.
There were no downfalls sufficient to eliminate this portion of the design.
Hence, into manufacture, test, and service. What was the benefit portion of the change in approach? Anyone?
A possibility of course, exists that single pilot operation, contingent on the building of an extensive record of safety thus equipped, might be "just around the corner"? Awaiting BEA's opinion on the matter....
On the other hand, it may be that the determination was simply that it was unimportant for the Pilots to "see" the other's controls. Actually, that had to have been one conclusion, perhaps still held?
In the development portion of the design, it occurs of course that separated controls were a new direction. The risks were no doubt delineated, assessed and addressed.
There were no downfalls sufficient to eliminate this portion of the design.
Hence, into manufacture, test, and service. What was the benefit portion of the change in approach? Anyone?
A possibility of course, exists that single pilot operation, contingent on the building of an extensive record of safety thus equipped, might be "just around the corner"? Awaiting BEA's opinion on the matter....
On the other hand, it may be that the determination was simply that it was unimportant for the Pilots to "see" the other's controls. Actually, that had to have been one conclusion, perhaps still held?
Last edited by Lyman; 13th May 2012 at 20:29.
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes
on
0 Posts
Trying to get out the corner
Hi,
DW:
The corner they entered (ultimately in the trees) was only "painted" by the pilots? Or the designers "preprogrammed" (with the new concept, protected FBW plane) the corner?
Would not be safer to allow a pilot to just exit the corner when absolutely necessary?
Rigid programming (hard limits) is really necessary? The pilots really need this kind of "protection"?
DW:
...as they tried to get out of the corner they'd painted themselves into.
The corner they entered (ultimately in the trees) was only "painted" by the pilots? Or the designers "preprogrammed" (with the new concept, protected FBW plane) the corner?
Would not be safer to allow a pilot to just exit the corner when absolutely necessary?
Rigid programming (hard limits) is really necessary? The pilots really need this kind of "protection"?
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,777
Likes: 0
Received 0 Likes
on
0 Posts
When you know the history of AF447 and (as far many saying) formation - training of new pilots it seems that strict limits are needed 
If they had been strict in AF447 .. Hall could have said in reaction to SS command to climb :
I dunno our speed ... but ..
Your throttles are set at VVV
The weight of the aircraft is XXX
The current altitude is YYY
The temperature is WWW
The CG is located at ZZZ
If you want climb now you're going to put us in a very dangerous situation that's why I will limit your ability to climb
Will give you update ASAP
If they had been strict in AF447 .. Hall could have said in reaction to SS command to climb :
I dunno our speed ... but ..
Your throttles are set at VVV
The weight of the aircraft is XXX
The current altitude is YYY
The temperature is WWW
The CG is located at ZZZ
If you want climb now you're going to put us in a very dangerous situation that's why I will limit your ability to climb
Will give you update ASAP
Join Date: Jan 2005
Location: W of 30W
Posts: 1,916
Likes: 0
Received 0 Likes
on
0 Posts
Habsheim
Thanks for that link RF4 :
Habsheim : Airbus Response to the Criticisms to the BEA Final Report
By any chance, would you have also the document :
L’Affaire/The Case by Mr R.A. Davis which was the main reason of the Airbus response.
To note that Mr R.A. Davis has been at the head of the prestigious AAIB during 15 years, and not only "an aircraft accident consultant" as the Airbus Response likes to describe him. Also, he was specialized in the Flight Recorders decrypting …
Obviously, there is still a tremendous interest for Habsheim.
I just don’t understand why PPRuNe refused me the possibility to start a thread exclusively dedicated to Habsheim … ?
Habsheim : Airbus Response to the Criticisms to the BEA Final Report
By any chance, would you have also the document :
L’Affaire/The Case by Mr R.A. Davis which was the main reason of the Airbus response.
To note that Mr R.A. Davis has been at the head of the prestigious AAIB during 15 years, and not only "an aircraft accident consultant" as the Airbus Response likes to describe him. Also, he was specialized in the Flight Recorders decrypting …
Obviously, there is still a tremendous interest for Habsheim.
I just don’t understand why PPRuNe refused me the possibility to start a thread exclusively dedicated to Habsheim … ?