AF 447 Thread No. 6

[hetfield]

It's allowed (certified) for the (deleted) pilots hand fly the plane at high altitude. So do it at your next check ride with your company, FAA or whatever examinar @ FL 350 or so.

Have fun...

[HarryMann]

5. PF believed he was applying a correct procedure of stick back, apply TOGA and airbus protections especially alpha prot would prevent the bus from stalling with minimal height loss.A good reason then, for having a proper stick shaker and pusher in ALT mode, as almost all other civil jet aircraft have and have had for many decades now.

There also appears to be little reason for allowing the THS trim system to assist a pilot to trim right into and beyond the stall at altitude and cruise speed...

Yes, yes, i know... bad piloting, inexplicable piloting but that is why stick shakers and pushers have been around for years - because it is known that pilots stall aeroplanes and the consequences are often that with a large swept wing jet a/c (however tailed), recovery cannot always be guaranteed in a set height lossor limit 'g' once badly stalled (c.f. stall netry just averted).

What was the argument then for certifying in Alt2 without a stick shaker and pusher ?

[DB64]

:D
@VGCM66 Is there much more to say?

p.s. for all the A haters from B factoryland....B jets are not without faults; many deadly; and had it not been for government cash injection it would not be the mega company it is today (protectionism as much as the US would like it to be is not exclusive)...therefore I ask those of you with issues to do your homework and perhaps have a bit of understanding, acceptance and humility before passing judgement.

[xcitation]

What more is there to argue?

Before you start attacking the dead pilots you need to do a bit more research here (http://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-070.aspx). Are you aware that QF72 was probably fresh on AF447 pilots minds which included false stall warnings and failed PFDs followed by a steep dive that was recovered by a continuous stick back! Note that QF72 had the benefit of visual references (day time + good weather).

The AF447 pilots probably had less than 60 seconds to get ahead of the aircraft that had run away from them. This was not an easy situation, totally untrained for. In this situation panic can occur quickly. You have to ask why did they behave the way they did. You need to dig deeper to find why they made the mistakes.


The crew were also receiving aural stall warning indications at this time, and the airspeed and altitude indications on the captain’s primary flight display (PFD) were also fluctuating.
Given the situation, the captain asked the second officer to call the first officer back
to the flight deck.
At 1242:27, while the second officer was using the cabin interphone to ask a flight
attendant to send the first officer back to the flight deck, the aircraft abruptly
pitched nose-down. The captain reported that he applied back pressure on his
sidestick to arrest the pitch-down movement. He said that initially this action
seemed to have no effect, but then the aircraft responded to his control input and he
commenced recovery to the assigned altitude. The aircraft reached a maximum
pitch angle of about 8.4 degrees nose-down during the event, and a maximum g
loading of -0.80g was recorded. The aircraft descended 650 ft during the event.

[gums]

A few good points recently.

I hitch hike on RF4's comments, if you will excuse me.

The military guys here flew jets with vastly different operational requirements, and some of our jets had vastly enhanced performance characteristics than the 'bus. So we flew the things to the edge of the envelope and maybe beyond during training. When we encountered a "bad" condition, we usually had seen it before and responded according to procedure and training. This was not the case with the AF447 crew.

There is no substitute for experience. You can fly a simulator all you want, but until you see and feel the real thing in the real situation, you are not fully prepared. Simply following a rote procedure will work 90% of the time, but that remaining 10% can be, and often is, fatal. It is very hard, very expensive, and maybe foolhardy, to experience stalls and high AoA flight conditions in a big commercial jet. Only way around this is to have a small fleet of planes to see and feel the flight characteristics of stall entry, and recovery. Sorta like the Shuttle folks used to practice their approaches.

Another thing I saw when checking out folks in the USAF Reserve and Guard was how commercial airline folks could go from flying the Viper or SLUF or Thud or Double Ugly on weekends to a 737 or 757 for their "day" job. i would take those guys and gals any time in a big jet that had entered unknown territory. So there IS A WAY.

The design philosophy that assumes engineers can build a jet that "protects" the crew and SLF's from all possible contingencies is failing us. As with your auto, you must be able to master the beast without a plethora of control laws and "back up" modes, and such. You must first of all, and lastly, be a pilot.

I'll go back to my cave now....

[jcjeant]

Hi,

DB64
p.s. for all the A haters from B factoryland....B jets are not without faults; many deadly; and had it not been for government cash injection it would not be the mega company it is today (protectionism as much as the US would like it to be is not exclusive)...therefore I ask those of you with issues to do your homework and perhaps have a bit of understanding, acceptance and humility before passing judgement. And what is your advise for all the A haters from A factoryland ?

Xcitation
This was not an easy situation, totally untrained for. In this situation panic can occur quickly. You have to ask why did they behave the way they did. You need to dig deeper to find why they made the mistakes.

You give yourself the answer ....
totally untrained for

[rudderrudderrat]

There are a several QRH procedures that call for Full Back Stick.
WIND SHEAR:
SRS ORDERS .... FOLLOW
This includes the use of full back stick if demanded.
If the FD Bars are not available , use an initial pitch attitude of 17.5 degs with full back stick, if necessary.

WINDSHEAR AHEAD:
Thrust Levers ….. TOGA
SRS ORDERS .... FOLLOW
This includes the use of full back stick, if required.

EGPWS ALERTS
PITCH ….. PULL UP
Pull to full back stick and maintain in that position
THRUST LEVERS …. TOGA

The pilots will have practised all of those procedures in the simulator, and will have gone away with the association of TOGA and Full back stick seems to work OK. Piloting skills don't seem to be required, simply pull back and let the computer fly the aircraft in pitch.

It is not mentioned anywhere that the "piloting technique" of respecting Alpha Max should be employed, and to relax the back pressure when very close.

Is it reasonable to ask a pilot to fly one particular way when in Normal Law, and a different way when in Alternate Law?

If AB had fitted a side stick buzzer, which was activated when approaching ALPHA MAX in NORMAL LAW, then he might have had the opportunity to practice flying the correct pitch attitude / angle of attack during the Wind Shear and EGPWS Alerts, on the edge of the Stick Buzzer / Shaker.

It may have reminded him to respect the stick shaker, when at FL 350, rather than go for TOGA & FULL Back stick again.

One solution is to simply change the crew - but if they failed to recognise their predicament due cockpit design, training, QRH procedures, etc. then you can bet there will be another crew able to do the same somewhere else.

@gums
You must first of all, and lastly, be a pilot.
I agree 100%. :ok:

@ventus45
It is way past high time that the "sim level D" mindset is smashed. We had to do all our B707 emergency exercises in real life, Stalling, Emergency Descent, EFTO etc. Unfortunately we were writing off more aircraft during training than we did in normal passenger operations. There was no good reason to continue using the real thing once simulator fidelity came close. A crew learns far more by freezing the sim before impact than chatting to them in their hospital beds - or worse.

[curvedsky]

VGCM66 - well said. And a fine Flight article too. AF447's initial altitude drift went virtually unchallenged (http://www.flightglobal.com/articles/2011/08/12/360432/af447s-initial-altitude-drift-went-virtually-unchallenged.html)

Please see post #1386 on 3 AUG 11 which seeks the figures for AR447 buffet boundary at the time of the accident. They were clearly exceeded and the inevitable aerodynamic upset resulted.

Has anyone listed these relevant AF447 Flight Manual figures yet?

http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-70.html

[HazelNuts39]

Has anyone listed these relevant AF447 Flight Manual figures yet?Buffet boundary for AF447 weight at FL380 and 1 g is M=0.63.

[Linktrained]

John3775 #743

".. the people on the flight deck were morons.... 2 guys refused to acknowledge a problem... "

Whilst other modes of transport CAN stop and have time to think, this crew had just FOUR minutes...or less, and in Test Pilot country.

A test pilot might well have been flying by day, clear of cloud and anticipating the abnormal.

"Morons" is prehaps unreasonably harsh, especially as you have read all the other comments for two years.

[Zorin_75]

Linktrained,

I fully agree that some respect is called for. Though I suppose with regards to test pilot territory you're talking about unstalling a widebody going down 10000fpm at 60 deg AoA, not about keeping their plane reasonably straight and level for a minute or so? After all the former only resulted from failing at the latter...

[ChristiaanJ]

There are various ways to tell 'non-test-pilots' that they are entering 'test pilot territory', and test pilots lost their lives to get those boundaries established.

"Stall Stall Stall" is one, and unlike what some people here still seem to think, it's a warning about 'approach to stall', it doesn't mean (yet) the aircraft is stalled.

The same applies to stick shakers and stick pushers.....

Once those warnings are not heeded (either because of the perceived or known or 'advertised' unreliabilty of the warnings itself, or the incapacity of the pilot of how to deal with them) disaster in 'test pilot territory' iis often only just around the corner.

"Those who can't learn from history, are bound to repeat it", and another test pilot, and other pilots and passengers, will have died in vain.

[Linktrained]

PA and PNF did not appear to KNOW that they were stalled OR descending at 10,000 fpm, until they were at 10,000ft. ( AoA is on the FDR, I believe.)

Perhaps Approach to Stall Training should be called 447, just to keep that lesson well learned by future generations.

[VGCM66]

More and more I keep on thinking this crew had been probably well prepared and rehearsed for take-offs and landings but cruising had been always left to the automatic system. As time went by and comfortable routines became the norm, they unknowingly became less proficient high altitude PILOTS. It didn't take much for life to prove them deadly wrong. All three of them in their minds avoided looking and addressing the fast decrease of Altitude because they were simply blank about what to do about it. They never thought that one day they might have to fly manually the airplane without the help of the FBW during the cruising phase. Alternate law or even Direct Law, impossible. Those situations could never happen because is simply too extreme and it would mean that we'll all be dead by then. But the remotely impossible and improbable extreme came to be and the tragic outcome did happened as anticipated. That final outcome could have had a different and happier ending but good old human complacency was already hard at work and too deeply rooted .

[ChrisJ800]

Yet there have been plenty of survivable UAS events including in Airbus's. For example see Incident: Jetstar A332 near Guam on Oct 28th 2009, series of ECAM messages (http://avherald.com/h?article=421fb22e/0000)
where the aircraft stays within 100 feet of its assigned FL during the UAS event.

[Ian W]

Yet there have been plenty of survivable UAS events including in Airbus's. For example see Incident: Jetstar A332 near Guam on Oct 28th 2009, series of ECAM messages
where the aircraft stays within 100 feet of its assigned FL during the UAS event.

This is not an equivalent incident. The other "holes in the cheese" were not there - in moderate turbulence at night and automatics handing over not in straight-and-level

[whenrealityhurts]

I am curious...are there any mechanical attitude instruments in the Airbus or is it all tube displays.

I ponder a cockpit where all the tv screens go out, lighting strike...what would the pilot have for attitude reference?

[jcjeant]

Hi,

This is not an equivalent incident. The other "holes in the cheese" were not there

Indeed .. you right
In the other cases .. it was good pilots in the cockpit
It was not the case for AF447 and that's was a big supplementary hole in the cheese (read BEA reports and the BEA press meetings)
That's the sad reality .. and this is a real problem for Air France

[ChristiaanJ]

I am curious...are there any mechanical attitude instruments in the Airbus or is it all tube displays.

I ponder a cockpit where all the tv screens go out, lighting strike...what would the pilot have for attitude reference?
That's a question I've asked myself a few times, too.
The present-day standby instruments use small LCD screens too, which still rely on some kind of separate secure electrical supply, and presumably so does the attitude reference (gyro of some type).

I 'grew up' in the days of the "SFENA", a small 3" standby horizon with its own hi-speed hi-inertia gyro, that would run for several minutes after a total loss of power. The display was purely mechanical, so the attitude information was still displayed.
At some point it equipped about 70% of the world's airliners, including Concorde and 747.
And it's credited with being the ultimate aid in a few OMG situations, and bringing the plane home (a Caravelle with a total electrical failure - or lightning strike, I'm not sure - comes to mind).


I worked for SFENA, but not in that division. I saw the first LCD display standby horizons arrive, but never got the answers to their reliabilty compared to the old "spinning top" version in extreme situations.

[xcitation]

A few misguided comments about test pilot territory.
From what I have heard liner test pilots say when they test the edge of the envelope it is in a highly controlled and low energy way. The goal is to keep control and have the ability to return to the envelope quickly.
These guys pushed aggressively through the envelope to the point of invalidating (breaking) the stall warning. The pilots took AF447 it beyond normal test conditions.
AF need to address why all 3 pilots with their training would not mention "stall" or "décrochage". All 3 pilots could hear it. I don't think Airbus and BEA would have that answer.

[VGCM66]

Now we'll get somewhere:

Airplanes are so automatic, pilots are forgetting how to fly them, says federal panel - NYPOST.com (http://www.nypost.com/p/news/national/auto_pilots_scary_skies_AheRGb0IfSiSp8QqGMcdPL?CMP=OTC-rss&FEEDNAME=)

[bubbers44]

This won't fix anything because once or twice a year having upset recovery does not a pilot make. They will check one more square for the ten minutes they did that training but it won't fix anything because ten minutes is not even close to enough time and the airlines don't want to invest any more sim time in a meaninful two hr session. There are times during flight you can handfly legally per FAA usually now in the lower altitudes below RVSM but so many airlines don't want their pilots to do it at all. On our major airline almost everybody did a lot of hand flying so we didn't have a big problem with automation dependency. Also all had been on board at least 12 years so no new guys.

[DozyWannabe]

They will check one more square for the ten minutes they did that training but it won't fix anything because ten minutes is not even close to enough time and the airlines don't want to invest any more sim time in a meaninful two hr session.

So, as I've been saying from the outset, pilots' unions and airline safety campaign groups need to band together and, as FDR told the progressive groups that helped him into power, "make [them] do it".

As I said earlier, you're probably not going to get a better time than this for the next decade, or at least until the next LOC accident claims more lives. Ask the right questions and tell your stories to the right people and you could have airline management on the ropes.

[ChrisJ800]

Quote IanW:
This is not an equivalent incident. The other "holes in the cheese" were not there - in moderate turbulence at night and automatics handing over not in straight-and-level

The Jetstar incident was nighttime, around midnight local time, in cloud and with lightning around. But this is just one example. I believe there is a list somewhere of over 30 UAS incidents that were successfully recovered from.

[galaxy flyer]

Bubbers44

I went thru the "old" school USAF UPT, lots of acro, lots of under the hood acro, and lots of recoveries; then fighter RTU same torture by ex-Vietnam types who loved handing the plane back, under the "tent", out of speed, straight up to see how you would handle it. Now, even in the AF, the T-1 program has none of that. Funny, when I last went to NTPS and did upset training, I all came back like riding a bicycle despite years of not doing it.

The lesson: this training needs o be "imprinted" early on and reinforced to the point of reaction not deep thinking.

[Machinbird]

AF need to address why all 3 pilots with their training would not mention "stall" or "décrochage". All 3 pilots could hear it. I don't think Airbus and BEA would have that answer.

In other words: Has some phase of the training de-sensitized the crews from hearing and responding to the stall alarm? Do Sim instructors debrief items while the stall alarm is sounding? Have crews somehow learned to ignore or 'listen through' the stall alarm?

The rudder pedal shaker in the F-4 was excellent for gaining my attention promptly. Several threads before, I mentioned a seat shaker as probably the most viable tactile stall warning technique on a stick flown FBW transport aircraft where the crew may fly with feet off pedals and even hands off stick. With the AF447 crew demonstrating that they did not respect/respond to the stall warning annunciation and crickets, there must be a need for a better way to get a pilot's attention. (Yes, PF did appy TOGA at the second set of stall alarms together with aft stick to keep the nose from falling :*)

[Mad (Flt) Scientist]

With the AF447 crew demonstrating that they did not respect/respond to the stall warning annunciation and crickets, there must be a need for a better way to get a pilot's attention.
Agree. Tactile cues used to be thought essential in such a role. No need to introduce seat shakers though. Stick shakers are a tried and tested way of attracting a crews attention. But they aren't part of the AB FBW philosophy and it might be quite a wrench to introduce them now.

[bubbers44]

With all of their stall warnings going off and not responding, I don't think a baseball bat hitting them on the head would have helped. The captain by the time he got up there in his groggy condition and as confusing as the situation was by then probably couldn't help in the limited time he had to respond. Maybe Air France should hire qualified pilots in the future. Maybe everybody should. I know, that costs more money.

[bubbers44]

If I ever need heart surgery or brain surgery, I hope the airline industry isn't hiring my doctor.

[Denti]

That's a question I've asked myself a few times, too.
The present-day standby instruments use small LCD screens too, which still rely on some kind of separate secure electrical supply, and presumably so does the attitude reference (gyro of some type).

As far as i know both Boeing and Airbus use a Thales system as standby instrument. In the 737 the ISFD (integrated standby flight display) has its own internal battery pack that provides power for 150 minutes completely independent of the rest of the aircraft, its own internal inertial sensors which even act as the third inertial platform during fail operational auto land operation. The only inputs it receives is heading information from the left IRS and ILS information from NAV 1.

According to our maintenance those units have a much lower failure rate than their old mechanical counterparts, not surprising as they have no moving parts. Additionally those old units were powered by the general aircraft batteries which only provide enough power for 60 minutes. Inertia keeps them running for a bit after power is off, however the attitude reference becomes unreliable very soon after power is removed, unlike the ISFD which runs happily on its own even after the rest of the instruments fail because the aircrafts battery is depleted. In that case you need a flashlight to read the magnetic compass for heading reference though. Additionally it uses the same presentation as the PFDs, has no parallax error and is therefore easy to use from both seats, and has its own light-source of course which keeps it usable for those 150 minutes in darkness as well.

[Machinbird]

Mad Scientist

No need to introduce seat shakers though. Stick shakers are a tried and tested way of attracting a crews attention. But they aren't part of the AB FBW philosophy and it might be quite a wrench to introduce them now.
Do you really think you can shake the short Airbus stick sufficiently to draw attention without also making control inputs?
And what if the pilot is not holding onto the stick when the alarm is triggered?
Then again, how would you alert the PNF?

It is relatively easy to shake the seat and no chance of unintended control input. It will get your attention. And it doesn't occupy your overworked visual-aural channel.

It isn't part of AB FBW philosophy because the aircraft were supposedly virtually unstallable. Guess that bit of philosophy needs a revisit in light of current experience:}.

[CelticRambler]

Le Figaro - France : L'incident qui relance le dbat sur l'AF 447 du vol Rio-Paris (http://www.lefigaro.fr/actualite-france/2011/09/06/01016-20110906ARTFIG00363-l-incident-qui-relance-le-debat-sur-l-af-447-du-vol-rio-paris.php)

Le Figaro today publishes a report of a near-perfect repeat of the AF447 incident - but without the 200+ fatalities.

En croisière au FL 350, en IMC de nuit, un A340 en provenance de CCS traverse une zone de
turbulences sévères, 10 nm au nord de la position 18N060W.
L'avion subit un fort gradient de vent (+22 kt de vent effectif en 5 s), avec une vitesse atteignant
Mach 0.88 (MMO de 0.86) pour une CAS=304 kt avec déclenchement de l'alarme Overspeed.
Simultanément, une déconnexion de l'AP se produit. L'assiette de l'avion augmente ensuite
progressivement vers 11°, avec un vario voisin de 5000 ft/min.
Moins d'une minute après la déconnexion de l'AP, l'avion atteint le FL380 avec une vitesse en
diminution vers Mach 0.66 pour une CAS=205 kt (Mach GD =0.78, GD=276 kt).
La diminution de l'intensité des turbulences s'accompagne d'une réduction de l'assiette de l'avion,
puis d'un retour à des paramètres de vol normaux.
La période de turbulences dure deux minutes avec une intensité plus prononcée lors des 30
premières secondes. Plusieurs pics d'accélération verticale sont enregistrés, les valeurs limites
atteignant +1.7 g/+0.5 g.
Les informations météorologiques fournies à l'équipage n'indiquaient pas de turbulences dans cette
zone du parcours. Le radar météo était en fonctionnement.
Aucun blessé n'est à déplorer parmi les passagers et 2 CRAT bénins sont rédigés par l'équipage
commercial.
La rapidité de transmission de l'annonce «ici le poste de pilotage, PNC assis attachés, turbulences
fortes », a contribué à limiter les dommages corporels en cabine.
Mise à jour 28/07/2011 : cet évènement fera l'objet d'une enquête du BEA à laquelle Air France sera
associée.

Assuming the incident and the document are real, and assuming the much-criticised original pitot tubes were replaced as recommended, this would seem to narrow the debate over potential causes by one parameter at least.

[AlphaZuluRomeo]

Le Figaro today publishes a report of a near-perfect repeat of the AF447 incident - but without the 200+ fatalities

I must disagree, Sir.

- no speed data loss on this A340, or so it seems so far
- on the other hand, no overspeed alarm on AF447 (which would explain the climb) (and I know that the CVR mentionned "je crois qu'on a une vitesse de fou, là" or something like that, but it was much later, far into the stall).
- no mention of a reversion to alternate on the A340 from Caracas. Assuming the NORMAL LAW, the climb seems adequate, then. If overspeed, then reduce thrust and climb, that's the way the high speed protection works AFAIK.
- if still in NORMAL LAW, the stall was not to be feared on this A340 : the overspeed protection worked, I see no reason that the high AoA protection would not have kicked in, if needed (perhaps it has, for all we know).


NB: This new incident should (and is, apparently) investigated. This is not a subject of debate for me. :ok:
But the article seems to link AF447 & this incident far too much. := Paper selling agenda? :oh:

[AlphaZuluRomeo]

Me again (sorry)

What seems, for now, more linked to AF447 is the publication yesterday (sept the 5, 2011) by the BEA of the report of the work group on the triggered transmission of flight data (inflight).
This report appears to be available only in french, so far. There (http://www.bea.aero/fr/enquetes/vol.af.447/transmission.declenchee.de.donnees.de.vol.pdf).
I don't know if an english version will follow?

[NARVAL]

To help our non french-speaking friends, here is a quick translation if needed.
It is an Air France Flight safety information report.

* Level bust en turbulences
En croisière au FL 350, en IMC de nuit, un A340 en provenance de CCS traverse une zone de
Cruising at night at FL350 in IMC, an airbus 340 coming from Caracas enters a zone of severe
turbulences sévères, 10 nm au nord de la position 18N060W.
turbulence ; 10 nautical north of 18N060W
L'avion subit un fort gradient de vent (+22 kt de vent effectif en 5 s), avec une vitesse atteignant
The airplane meets a strong wind shear (+ 22kts in 5 seconds) with an increase of speed up to Mach
Mach 0.88 (MMO de 0.86) pour une CAS=304 kt avec déclenchement de l'alarme Overspeed.
0,88 (MMO is 0,86) with a CAS of 304kt triggering the Overspeed alarm.
Simultanément, une déconnexion de l'AP se produit. L'assiette de l'avion augmente ensuite
At that moment, the Auto pilot disconnects. The plane’s pitch attitude reaches progressively
progressivement vers 11°, avec un vario voisin de 5000 ft/min.
11 degrees with a climb rate close to 5000 fett per minute.
Moins d'une minute après la déconnexion de l'AP, l'avion atteint le FL380 avec une vitesse en
Less than one minute after the Auto pilot has disconnected the plane reaches FL 380
diminution vers Mach 0.66 pour une CAS=205 kt (Mach GD =0.78, GD=276 kt).
With a speed coming down to M 0,66 and a CAS of 205 knots
La diminution de l'intensité des turbulences s'accompagne d'une réduction de l'assiette de l'avion,
The lessening of the turbulence intensity is met by a reduction of the pitch angle ;
puis d'un retour à des paramètres de vol normaux.
Then by a return to normal flight parameters.
La période de turbulences dure deux minutes avec une intensité plus prononcée lors des 30
The length of the turbulence event is of two minutes with a peak during the first thirty seconds.
premières secondes. Plusieurs pics d'accélération verticale sont enregistrés, les valeurs limites
Several peaks of vertical accelaration are recorded with peaks at 1,7g and 0,5 g.
atteignant +1.7 g/+0.5 g.
Les informations météorologiques fournies à l'équipage n'indiquaient pas de turbulences dans cette zone du parcours. Le radar météo était en fonctionnement.
Meteorological information in the flight crew’s briefing did not indicate any turbulence on this part of their route.The weather radar was on.
Aucun blessé n'est à déplorer parmi les passagers et 2 CRAT bénins sont rédigés par l'équipage commercial.
No passenger was harmed and two medical reports were filed by the cabin crew for not serious injuries.
La rapidité de transmission de l'annonce «ici le poste de pilotage, PNC assis attachés, turbulences fortes », a contribué à limiter les dommages corporels en cabine.
The speed with which the cockpit alerted the cabin (here is the cockpit speaking, commercial crew sit down and fasten your belts ; severe turbulence coming » helped to contain physical damage to the crew.
Mise à jour 28/07/2011 : cet évènement fera l'objet d'une enquête du BEA à laquelle Air France sera associée.
This event will be the subject of a BEA enquiry and report, Air France will cooperate in that work.


Forgive my sometimes stumbling english. Te protection associated in normal law with an overspeed did in fact apply.
We lack information on angle of attack reached, and engine's thrust variations. I think we should wait for the BEA reportt. But i cannot help thinking that "the cure is sometimes worse than the illness"...Heavy handed automatic protection at high altitude maight have led to a very difficult situation (the speed went down to 205 knots after all) compared to a momentary excursion in the overspeed, which would not last as it was due to turbulence in level flight).

[Zorin_75]

Le Figaro today publishes a report of a near-perfect repeat of the AF447 incidentAs far as I can gather with my rusty French, in this case there was no UAS and no alternate law, but rather overspeed protection kicking in? If so this would have been quite different from 447...

[HazelNuts39]

There seem to be some similarities with this incident (http://www.aaib.gov.uk/cms_resources.cfm?file=/Airbus%20A330,%20C-GCWD%20Airbus%20A340,%20TC-JDN%2006-2001.pdf).

[jcjeant]

Hi,

http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-39.html#post6683666

At that moment, the Auto pilot disconnects. The plane’s pitch attitude reaches progressively
11 degrees with a climb rate close to 5000 fett per minute
Less than one minute after the Auto pilot has disconnected the plane reaches FL 380I wonder if this is the result of the automatism (overspeed protection in normal law) or if this is the result of the automatism mixed with a pilot action (pull on SS)
Nothing about in the note ...
Curious to read BEA preliminary report about this (provided the recorder FDR was preserved and not erased like for the AF445 case !)

[mm43]

The BEA's Report by the Triggered Transmission of Flight Data Group (http://www.bea.aero/en/enquetes/flight.af.447/triggered.transmission.of.flight.data.pdf) was published last March and I recall has been available on their website since about 20 March 2011.

Edit :: the correct date is:- 15 June 2011.

[gums]

I had seen the reports about the A340 incident, but didn't see the control law logic back then. I subsequently saw that "sub-law" in some of the great data we have had on this forum.

I initially considered the alpha prot limit as a contributing cause, especially the "automatic" pull to that limit despite the basic gee command. then we got the pilot stick inputs, so I disregarded it.

One mo'time! Confusing reversion scheme and flying so close to the "limits" programmed that we get "overspeed", "alpha prot" and "stall warnings" when the jet deviates only slightly from a "stable" flight condition.

Big surprise about the recommendations was lack of a recommendation to look at the flight control reversion sequence and logic and implementation. Although the pilot attempted to re-engage the A/P twice ( wow! what?), he took control and recovered.

[AlphaZuluRomeo]

@ mm43 : oops, my mistake, then. The english version was first, for once.
Anyway, thanks for pointing it :)

[Clandestino]

It's allowed (certified) for the AP to quit and make the pilots hand fly the plane at high altitude.Surprise...shock...horror. And not just APs! Engines, radios, NAVs are also allowed to malfunction from time to time and poor pilots are expected to cope with it! Is it realistic thing to expect from mere human being?

Yes, yes, i know... bad piloting, inexplicable piloting but that is why stick shakers and pushers have been around for yearsNope, they are not to be considered poor piloting compensators. They are fitted if certifying authority deems that aeroplane stalling characteristics warrant their installation. They may help slightly distracted pilot but they are of limited value with totally incapacitated one. As is anything we came up with so far.

The AF447 pilots probably had less than 60 seconds to get ahead of the aircraft that had run away from them.Aeroplane was not getting away from them. CM2 has chased her away pretty actively.

Is it reasonable to ask a pilot to fly one particular way when in Normal Law, and a different way when in Alternate Law?Is it reasonable to ask me to control the roll by spoilers alone when right roll control linkage gets jammed and I get no feedback via yoke whatsoever? Is it reasonable to expect my F/O to fly us back to the tera firma with no spoilers and thus reduced control if my side is stuck? Was it reasonable to expect Genotte/Michielsen to survive when Gremlin hit took out all of their A300 hydraulics? How about Fitch/Haynek/Records?

For Finnegan's sake, the pilots are expected to cope with the degradation of flying qualities as far as they are able, not by the law of the men, but by the simple law of self-preservation.

We had to do all our B707 emergency exercises in real life, Stalling, Emergency Descent, EFTO etc. Unfortunately we were writing off more aircraft during training than we did in normal passenger operations. There was no good reason to continue using the real thing once simulator fidelity came close. A crew learns far more by freezing the sim before impact than chatting to them in their hospital beds - or worse. Absolutely correct. Today's training is what aviation authorities believe to be optimal trade-off between training value, risks associated with flying and costs.


Do you really think you can shake the short Airbus stick sufficiently to draw attention without also making control inputs?
And what if the pilot is not holding onto the stick when the alarm is triggered?
Then again, how would you alert the PNF?1. Yes, I do, provided it turns out FBW Airbi meet criteria for their installation. It's stickshaker, not stickwaver.
2. Aural warning, already patented.
3. See 2.

I hate to say it but the people on the flight deck were...morons. I know, it is terrible to say.In general terms, I wouldn't say so. I don't think that background checks will find much extraordinary, like more than usual amount of re-training. IMHO there was something that debilitated them at the moment probes froze and did not let them out of its grip till the watery end. This something is what has do be drawn out into the light. To paraphrase Arab proverb: they were like children going into lion's den, unaware that the old nasty lion lives at high AoA. They forgot an old aviation cliche: (http://www.skygod.com/quotes/cliches.html)
To go up, pull the stick back. To go down, pull the stick back harder.

[rudderrudderrat]

Hi Clandestino,

For Finnegan's sake, the pilots are expected to cope with the degradation of flying qualities as far as they are able, not by the law of the men, but by the simple law of self-preservation.

In Post #751, I mentioned 3 QRH procedures which specify the use of Full Back Stick. It is not mentioned anywhere that the "piloting technique" of respecting Alpha Max should be employed, and to relax the back pressure / reduce the angle of attack when very close.

If in Normal Law, the piloting technique of respecting Alpha Max is not trained, then there is a chance that some crews won't respect it in Alternate Law either.

[Machinbird]

Quote:
Originally Posted by Machinbird
Do you really think you can shake the short Airbus stick sufficiently to draw attention without also making control inputs?
And what if the pilot is not holding onto the stick when the alarm is triggered?
Then again, how would you alert the PNF?

1. Yes, I do, provided it turns out FBW Airbi meet criteria for their installation. It's stickshaker, not stickwaver.
2. Aural warning, already patented.
3. See 2.Hi Clandestino, I see you are an equal opportunity commentor.
My experience with the rudder pedal shaker was that it was pretty vigorous and if such a shaker were to be bolted into a FBW control system, it would probably cause excessive motion. But the hand is much more sensitive than the foot, so you may well be correct.

Only problem I see with your comment 2 & 3 is that it doesn't seem to have worked in real life when the chips were down.

But I'm suspecting denial as being a root cause for lack of response among the 2 copilots. Something along the lines of, "How will we explain getting into a stall.?" How will we recover from it? Maybe it isn't a stall."

And the Captain was led down the path by the copilots who didn't want to tell him how badly they had lost control.
I've seen it before in aviation-sort of a better to die than to look bad attitude.

A pilot who maneuvers aircraft should be keeping a mental log of where their energy is. Something along the lines of: "I've gained 3000 feet, I must have lost 70 knots, but if I dive back down, I'll get it back."

The PNF seemed to be aware of how the PF was mis-handling the aircraft and should have been running a rudimentary energy tally. But it appears he was instead completely clueless.
Of course maybe I am expecting too much. None of the AF447 crew were ever tactical jet pilots.

[Clandestino]

If in Normal Law, the piloting technique of respecting Alpha Max is not trained, then there is a chance that some crews won't respect it in Alternate Law either. You are correct but then we can agree that there are chances that some crews will take off without clearance and smash their half-airborne 747 into side of another, some will put their trust in sole failed instrument and spin their 757 into sea, some will dive MD-11 from 4000 ft so steeply to leave themselves no room for recovery... etc.

That every Airbus pilot absolutely must know how protections work, when they are to be relied upon, when they are not to be trusted and that "Airbus can not be stalled" is a simple myth, pushed forward by misinformed & ignorant, shouldn't be matter of discussion at all. We may discus why it isn't so in real life.

If chances of needing maximum climb performance, achieved by pulling the stick to backstop in normal law are 1 to x, and chances of having no protections are 1 to y, then chances of having to observe alpha max on your own, manually are 1 to x times y. Not as easy as letting the computer wring out the maximum performance but not impossibly difficult for a pilot, either. IMHO it's very small (and avoidable) chance for a pilot to fly himself into windshear or CFTT in degraded control law. BTW, there's good reason we call those electronic gizmos "computers" and not "thinkers" or "deciders".

My experience with the rudder pedal shaker was that it was pretty vigorous and if such a shaker were to be bolted into a FBW control system, it would probably cause excessive motion.I can pretty safely assume that pedal shaker didn't affect the handling of your Rhino at all. Shakers oscillate with high frequency and low amplitude. Because of both, controls and aeroplane inertia, they don't affect the flightpath. With ideal control harmony being 1-2-3, I believe that eventual sidestickshaker needn't be nowhere near powerful as pedalshaker.


Only problem I see with your comment 2 & 3 is that it doesn't seem to have worked in real life when the chips were down.

It didn't work for the crews of AF447. According to BEA's intermediate report no2, there were 37 cases of pitot blockage on 330/340, apart from AF447. 13 of them could be studied further, as there was enough data available. In 5 of them crew descended following the stall warning.

Doesn't look like systemic problem to me.

If I include late captain Marvin Renslow's paradoxical reaction to stall warning, shaker and pusher into picture, then we might have systemic problem after all but it goes much deeper than aeroplane model, make and manufacturer.

And the Captain was led down the path by the copilots who didn't want to tell him how badly they had lost control. Another puzzling aspect of the accident is that nose-up attitude and unwinding altimeters should make clear to him what is happening yet did not.

A pilot who maneuvers aircraft should be keeping a mental log of where their energy is.Absolutely correct and not debatable.

I've seen it before in aviation-sort of a better to die than to look bad attitude.Of course, it is possible to do both at the same time. (http://www.skygod.com/quotes/cliches.html)

[gums]

I go with Clandestino about using a "vibrator" on the stick. In the AF447 case, the dude that kept pulling back would have felt it, as he was not just sitting there watching Otto try to fly the jet.

The 'bus stick is displacement, not force as we had in the Viper. The sensors can easily be tailored to pay no attention to the "buzzing" stick.

Need a Concorde dude here, as I bet its "stall" was very benign and a shaker would warn of getting too high of an AoA. My own experience in a delta was that there was zero "stall" as we think of it. The thing just got "mushy" as AoA went way up and drag exceeded power available. Very smooth, with only a very slight buzz that you could hear first, then got to where you could feel it. Viper was almost the same due to the automatic leading edge flaps.

Energy awareness discussion needs to be expanded here. Seems a basic component of the "pilot" skills that can be learned and trained to accomodate. The sailplane folks here shuld be very aware of energy management. I only had about 4 minutes of it, as Sully did, when my motors quit and I deadsticked the jet onto a runway.

[Machinbird]

Of course, it is possible to do both at the same time. (http://www.skygod.com/quotes/cliches.html)
Yes, even while sitting in an ejection seat.:(

[ChristiaanJ]

gums,
You're right, Concorde "stalled", or rather "mushed" much like another delta.
Not a good idea, because by then you were well on the back of the power curve, so there were both a stick shaker and a stick pusher (SFC, safety flight computer) to keep you out of trouble.

[RatherBeFlying]

And the Airbus control laws are designed by a committee of engineers over a period of several months.

I am sure that the engineers were thoroughly conscientious, but it definitely looks that the pilots did not know what airplane they were trying to fly -- well the word Alternate was pronounced, but there was no learned disquisition in the cockpit on the implications of Alt 2B, even though I am sure the committee of engineers spent several days talking it over.

Engineers and programmers can get a bit carried away with themselves when getting into recondite corners -- here we see a proliferation of flight laws and a crew unprepared for Alt 2B combined with UAS at high altitude.

Applying KISS retroactively, the pilots would have known what airplane they were flying if Normal Law was flown with a touch pad and the stick, rudders and trim wheel were reserved for Direct Law;)

In a previous thread I mentioned that the VSI and altitude displays did not alert the crew to the descent rate problem until the 10,000' digit dropped off the altitude readout -- i.e. the readout went from 5 digits to four. Only at that time did the crew verbalise the altitude.

[jcjeant]

Hi,

Information, 7 septembre 2011 (http://www.bea.aero/fr/enquetes/vol.af.447/info07septembre2011.fr.php)

[rudderrudderrat]

Thanks jcjeant,

"The BEA is to establish the working group "Human factors" whose creation was announced at the publication of the third progress report of investigation into the accident flight from Rio to Paris on 1 June 2009.

This working group aims to analyze all aspects related to the conduct of the flight:

actions and reactions of the crew over the last three phases of flight described in the third progress report, especially vis-à-vis the stall warning;
ergonomics of the cockpit;
human-machine interfaces.
This working group is composed of seven experts:
three BEA investigators specializing in Human Factors;
a psychiatrist expert in risk analysis;
Aviation Human Factors consultant;
a qualified airline pilot A330;
a test driver.
The BEA may call occasionally to other experts and consult, as appropriate, Airbus and Air France.

The group's work will start very quickly and should be completed by the end of December 2011. His reflections will be fed by the work group "Operations" and group "aircraft systems."

All these works will be recorded in the final report which will establish the causes of the accident and whose publication is expected in the first half of 2012."

Thanks Google Translator.

[Jig Peter]

The team(s) "doing" the Airbus FBW system did not include "just engineers" but also pilots, some of whom also had high engineering qualifications.
Also, Airbus FBW wasn't a "one-off" programme, but the logical continuation of the control philosophies on preceding programmes, and many of the members of the FBW teams had been involved with those programmes.
Don't go along the "uncontrolled mad programmer/engineer" route - it doesn't wash !

[ChristiaanJ]

Don't go along the "uncontrolled mad programmer/engineer" route - it doesn't wash !Thanks Peter....
I's vexing sometimes to see those comments from people that have never designed a flight control system, and that have no idea how such a system works....
No guys.... the 'mad' aviation 'engineers' mostly went out of fashion in the early 1900s.

[Linktrained]

Machinbird #790

About sixty years ago some high performance gliders were fitted with a " Total energy Variometer" which would show the relationship between speed lost and height gained (or vice versa). These would have been non-electric !

[Ian W]

Thanks Peter....
I's vexing sometimes to see those comments from people that have never designed a flight control system, and that have no idea how such a system works....
No guys.... the 'mad' aviation 'engineers' mostly went out of fashion in the early 1900s.

There are no mad engineers, and there are many very dedicated people. However, at each stage right down at low levels in the system assumptions are made.
For example: "No aircraft will be airborne if its speed is less than 60 Kts as read from the pitot tubes". There will also be misunderstandings coded perfectly into the software. It seems from reports here that outside air temperature was considered to be a stable variable - yet it can vary hugely very rapidly as you fly through warm updrafts and into cold downdrafts - making Mach number calculations for Vmm and Vmo unreliable.

These 'features', quirks and problems, sometimes based on well thought out good intentions, appear in every major software system. They need to be looked at and the logic flaws carefully fixed (or you insert even better bugs). It does not pay to be defensive about these problems - they exist. Unfortunately, some of these 'features' if occurring in rare combination (back to the holes in the cheese) can be very misleading or surprising for the line flight crews: Even if the reasoning behind them still makes perfect sense to the careful design engineers and flight test crews.

[xcitation]

Hi Clandestino,


Quote:
For Finnegan's sake, the pilots are expected to cope with the degradation of flying qualities as far as they are able, not by the law of the men, but by the simple law of self-preservation.
In Post #751, I mentioned 3 QRH procedures which specify the use of Full Back Stick. It is not mentioned anywhere that the "piloting technique" of respecting Alpha Max should be employed, and to relax the back pressure / reduce the angle of attack when very close.

If in Normal Law, the piloting technique of respecting Alpha Max is not trained, then there is a chance that some crews won't respect it in Alternate Law either.

"Alternate law and protections lo"(st) was verbalize by PNF after a slight delay from its onset. PF did not verbally acknowledge this. PNF did not press the issue.
PF was not to be aware of his climb to max altitude due to his stick back.

[DozyWannabe]

However, at each stage right down at low levels in the system assumptions are made.
For example: "No aircraft will be airborne if its speed is less than 60 Kts as read from the pitot tubes".

To be fair, that's a hypothetical extrapolation you're making from the rules and there's no guarantee that was the logic behind that decision.

[Ian W]

It may be a 'hypothetical' but almost every other aircraft in the world would use the undercarriage 'squat switch'. Someone made the decision to not use that. I am sure that there is a squat switch to send the 'OFF' ACARS message.
\
But it was just an example of assumptions and decisions buried in complex systems that are defensibly logical but which can have unexpected consequences.

[gums]

@ Dozy, I am gonna go with Ian W on the weight-on-wheels design consideration.

If you want both < 60 knots and WOW, a simple "and gate" works. If you want either, then the "or gate" works.

OTOH, seems the 'bus and other heavies use WOW for spoilers and such after touchdown, or am I off base? I'll bet most pilots would like the spoilers to be active above 60 knots, as they wouldn't do much to shorten the landing roll below 60 knots, ya think?

I also question the alpha protect sub-law that attempts to fly the plane at the alpha protect AoA when the stick is released/neutral versus the basic one gee command.

And there are other puzzling features I have seen in the manuals regarding the reversion laws.

[rudderrudderrat]

Hi Gums,

I agree with you and Ian W - simple WOW logic for stall warning activation.
If I'm airborne - I want to know if the angle of attack is excessive no matter what my indicated air speed tells me. (There is no mention in FCOM about the >60kt IAS logic)

OTOH, seems the 'bus and other heavies use WOW for spoilers and such after touchdown, or am I off base?
If only it was that simple!

This extract is from Airbus Safety First Magazine Feb 2010: (my bolding)

"3.2. Hard landings
Among hard landings, one specific category has been identified where by the hard landing occurred after a bounce. They fit to the following scenario (fig. 7):

No engine throttle reduction (retard) during the flare
No ground spoiler extension.
Bounce induced by a too high energy level and by the lack of lift destruction.
Engine throttle reduction performed during the bounce
Ground spoiler extension if the retard is performed within 3 seconds following the first touchdown.
Severe hard landing due to sudden loss of lift leading to a fall from a height of about 5ft to 15 ft.
It has been established that most of the hard landings occurring after a bounce are severe."

[AlphaZuluRomeo]

Already said, but anyway...

I've never seen an official (manufacturer's) document which stated :
If IAS < 60kt then we're on ground then stall warning should be off.

I fully concur with DozyWannabe : that's a hypothetical extrapolation you're making from the rules and there's no guarantee that was the logic behind that decision.
If you know of such a document, please let us know.


My guess about the logic stopping the stall warning:
- nothing to do with being on the ground : for that, as was said, re-said, re-re-said, test wheight on wheels.
- if IAS < 60kt, then assuming the AoA probe risks (too much to be acceptable) to output false/inaccurate data.
- then if IAS < 60kt, disregard AoA probes data as unreliable
- then you don't know your AoA, then you cannot have stall warning


I don't pretend this is really better (factually : it was not in AF447) but at least, before being sure, let's not assume Airbus folks just "forgot" WoW... It's as bad & unfair as saying that AF447 crew were idiots, and that all is their fault. :yuk: :yuk:

[Clandestino]

Isn't it funny how unthinking knee jerk reactions to surprise or sudden onset situations are generally not considered to be a good idea in human responses, but are allowed, indeed, mandated, by both policy and design, in computer control systems, especially those supposedly intended to protect those humans from their perceived failings.
The evidence, at high energy altitude at least, is starting to add up to: "The cure is worse than the disease".Humour is a matter of personal preference, yet I must state that I find your excellent example of straw man argument (http://en.wikipedia.org/wiki/Straw_man) not particularly funny.

If definition of knee jerk includes "quick, large, fast, precise, with positive feedback loop", then knee jerk reactions are required while flying in extreme circumstances, such as when one is getting cornered and prompt resolution is required, e.g. stall warning, GPWS maneuver, windshear escape. If not, forget about it at all. Whether my proposition of knee-jerk definition stands or not, UAS wouldn't call for knee-jerk reaction even in your wildest dreams.

Can we agree that half back stick, progressing to full was unwarranted and maladjusted knee jerk reaction to UAS that untimely terminated the lifespans of AF447 crew and passengers or are we going to attack the BEA's findings, so far?

Do you have a slightest idea what effects your cure has, when you pronounce it worse than disease or are you disregarding them and are just into concentrating on side effects?

However, at each stage right down at low levels in the system assumptions are made.
For example: "No aircraft will be airborne if its speed is less than 60 Kts as read from the pitot tubes". That the aeroplane with size and weight of A330, at 60 KIAS will be soaring through the air with grace and elegance of falling refrigerator and that therefore her airborne time at said speed will be most cruelly limited is not just an assumption. It's a fact.

PF was not to be aware of his climb to max altitude due to his stick back.He could have checked attitude and altitude. I am puzzled why he didn't.

I am sure that the engineers were thoroughly conscientious, but it definitely looks that the pilots did not know what airplane they were trying to fly -- well the word Alternate was pronounced, but there was no learned disquisition in the cockpit on the implications of Alt 2B, even though I am sure the committee of engineers spent several days talking it over.Brief summary of flight controls effects in Alt 2B, provided the aeroplane stays within flight envelope:

STICK FORWARD ........................................ NOSE DOWN
STICK AFT ................................................ NOSE UP
STICK LEFT ............................................... ROLL LEFT
STICK RIGHT ............................................. ROLL RIGHT
PEDALS LEFT ............................................. YAW LEFT
PEDALS RIGHT ........................................... YAW RIGHT

Ladies & gentlemen, aren't you forgetting the basics of instrument flying? Namely that successful instrument flying absolutely requires: idea where is aeroplane, where we want it to be and strong positive feedback loop between pilots actions and aeroplane reactions? Aeroplane banks and I don't want that? Give opposite command via stick, yoke, ram horn yoke, whatever happens to be in your hand at the time. How much is enough? 5, 15 or 30° ? Who cares, effects on the aeroplane can be easily read on AH, outside horizon or deducted from turn & bank, if you're going on partial panel and that's what guides pilots hand. Or at least those pilots that can be truly considerd to be proficient in instrument flying.

Considering the matter of untimely activation of alpha prot in normal law, mentioned here and having no relevance on AF447 AFAIK: while I admit I would prefer having its activation clearly anounced, it's not a such big deal. It pitches the aeroplane up mighty quickly but it gets disconnected by pushing the stick forward - which is what you'd be doing anyway if you're unhappy with aeroplane climbing on her own. Sitting, watching the pitch and altimeter go up and comenting " Ehhhh... what eez eet doing now?" is not likely to help.

Retired F4 and his former tactical fighter pilots colleagues have repeatedly mentioned "unloading the wing". Civilian equivalent of this is "PUSH FOR CONTROL" and is sadly neglected in training. Idea behind this is that when faced with loss of control of the unknown origin, most probably it is stall induced, so reduce AoA.

[rudderrudderrat]

Hi Clandestino,
That the aeroplane with size and weight of A330, at 60 KIAS will be soaring through the air with grace and elegance of falling refrigerator and that therefore her airborne time at said speed will be most cruelly limited is not just an assumption. It's a fact.
If you look at page 111 of the report, at time 02:10:15, the computed IAS was about 50 kts, the ISIS was 280 then fell rapidly to about 50 kts. The aircraft was still flying perfectly - and bore no resemblance to your refrigerator.

If I'm airborne and stalled - I want to know about it, especially with UAS.

The 60kt logic is normal with on ground logic to prevent nuisance warnings before take off.
There is no mention in FCOM of the stall warning being deactivated with IAS<60kts when airborne.

[GarageYears]

Pitot specification?

Has anyone access to the specification of the pitot system fitted to the A330?

Could it be that the difference between static and dynamic pressure at airspeed deltas of <60 knots is 'out of spec'? Somewhere in the past, I believe I read something related to pitot design and the issues of drain holes... or at least less accurate.

The presence of the drain hole effectively reduces the low speed sensitivity, since some of the sensed dynamic pressure is bled via the drain (or something like this). There is compensation for this effect, but at some point that gets iffy.

[jcjeant]

Hi,

Ground spoiler extension if the retard is performed within 3 seconds following the first touchdown.TAM A320 Conghonas related .... no retard .. no spoilers .....
http://www.pprune.org/rumours-news/394232-tam-3054-report-released.html
Brazil charges 10 over TAM Conghonas fatal overrun (http://www.flightglobal.com/articles/2008/11/21/319186/brazil-charges-10-over-tam-conghonas-fatal-overrun.html)

[DozyWannabe]

@gums, RRR, Ian W:

I don't think the <60kts in this case was intended to be tied in with ground mode - I suspect it was designed to cover another potentially false stall warning trigger. Remember that one of the main reasons pilots have ignored stall warnings in the past was because they were perceived as unreliable. If I was designing the system I'd have to weigh up the probability of a false stall warning triggering due to UAS causing an inappropriate response by the systems or the crew against the probability of the aircraft ever actually getting that slow in flight, which as logical people you have to admit is considerably higher in the case of the former than the latter. The problem we have now is that while the probability of the latter is low, it has in fact happened and now the design and logic path must be looked at from the ground up. As engineers will tell you, knee-jerk changes to design in order to react to a single failure mode are a bad move in general - one must be absolutely sure that the change has no knock-on effect.

@jcj - With all due respect, what does that have to do with this incident? The post you quote I don't think has to do with any logic change deriving from that accident (or the incident that preceded it), which in that case seemed to have been caused by a diligent attempt to slow down as much as possible in bad weather and use an old (more effective) procedure for engaging reversers - leading to the error the new (slightly less effective) procedure was designed to prevent.

[Clandestino]

If you look at page 111 of the report, at time 02:10:15, the computed IAS was about 50 kts, the ISIS was 280 then fell rapidly to about 50 kts. The aircraft was still flying perfectly - and bore no resemblance to your refrigerator.

1. I should have been more pedantic and write KEAS instead of KIAS, to exclude the case of speed indication loss. It would make it more understandable to those who are learning aerodynamics through Google search.

2. I should have been more pedantic and make clear that my response was referring to stalled phase of AF447 flight (at that time, indication below 60kt was realistic and not result of clogged pitots), as was the Ian W's claim to which I've responded.

3. Since you mention interim 3, it has some other pages, like 29. At 2:10:09 and 2:10:13, computed airspeed is still a mess, yet the stall warning goes off as the aeroplane is jerked into climb!
Where does that leave the theory that unreliable airspeed alone will rob A330 of stall warning?

If I'm airborne and stalled - I want to know about itLet me see.... you pull the stick and are shouted at that you are about to stall for 54 seconds, at least two (and probably three) airspeeds are agreeing and going down, eventually pitch is positive yet the altimeter is unwinding. Somehow you conclude that all those are not clues enough that you're stalled. I am at loss to explain this. Would you, please?

[GreatBear]

Greetings, old friends. I've been lurking in the daily background of this thread since the amazing recoveries from the sea floor; haven't had much to contribute, but I've been following the thinking nonetheless. Today I ran across this interesting cross-industry (marine) interpretation of Joan Lowy's August 30, 2011 AP article "Automation in the air dulls pilot skills." What happens when the electronics on your supertanker go dead and you realize you left your sextant at home? Perhaps of interest to those who have been developing this line of thought.

Maritime Professional (http://www.maritimeprofessional.com/Blogs/The-Final-Word-with-Joseph-Keefe/September-2011/Automation---Technology--Dulling-Mariner-skills-.aspx)

And for those who missed the Associated Press article, here it is complete:

OaklandTribune.com
Aug 30, 2:22 PM EDT

AP IMPACT: Automation in the air dulls pilot skill

By JOAN LOWY
Associated Press

WASHINGTON (AP) -- Pilots' "automation addiction" has eroded their flying skills to the point that they sometimes don't know how to recover from stalls and other mid-flight problems, say pilots and safety officials. The weakened skills have contributed to hundreds of deaths in airline crashes in the last five years.

Some 51 "loss of control" accidents occurred in which planes stalled in flight or got into unusual positions from which pilots were unable to recover, making it the most common type of airline accident, according to the International Air Transport Association.

"We're seeing a new breed of accident with these state-of-the art planes," said Rory Kay, an airline captain and co-chair of a Federal Aviation Administration advisory committee on pilot training. "We're forgetting how to fly."

Opportunities for airline pilots to maintain their flying proficiency by manually flying planes are increasingly limited, the FAA committee recently warned. Airlines and regulators discourage or even prohibit pilots from turning off the autopilot and flying planes themselves, the committee said.

Fatal airline accidents have decreased dramatically in the U.S. over the past decade. However, The Associated Press interviewed pilots, industry officials and aviation safety experts who expressed concern about the implications of decreased opportunities for manual flight, and reviewed more than a dozen loss-of-control accidents around the world.

Safety experts say they're seeing cases in which pilots who are suddenly confronted with a loss of computerized flight controls don't appear to know how to respond immediately, or they make errors - sometimes fatally so.

A draft FAA study found pilots sometimes "abdicate too much responsibility to automated systems." Because these systems are so integrated in today's planes, one malfunctioning piece of equipment or a single bad computer instruction can suddenly cascade into a series of other failures, unnerving pilots who have been trained to rely on the equipment.

The study examined 46 accidents and major incidents, 734 voluntary reports by pilots and others as well as data from more than 9,000 flights in which a safety official rides in the cockpit to observe pilots in action. It found that in more than 60 percent of accidents, and 30 percent of major incidents, pilots had trouble manually flying the plane or made mistakes with automated flight controls.

A typical mistake was not recognizing that either the autopilot or the auto-throttle - which controls power to the engines - had disconnected. Others failed to take the proper steps to recover from a stall in flight or to monitor and maintain airspeed.

The airline industry is suffering from "automation addiction," Kay said.

In the most recent fatal airline crash in the U.S., in 2009 near Buffalo, N.Y., the co-pilot of a regional airliner programmed incorrect information into the plane's computers, causing it to slow to an unsafe speed. That triggered a stall warning. The startled captain, who hadn't noticed the plane had slowed too much, responded by repeatedly pulling back on the control yoke, overriding two safety systems, when the correct procedure was to push forward.

An investigation later found there were no mechanical or structural problems that would have prevented the plane from flying if the captain had responded correctly. Instead, his actions caused an aerodynamic stall. The plane plummeted to earth, killing all 49 people aboard and one on the ground.

Two weeks after the New York accident, a Turkish Airlines Boeing 737 crashed into a field while trying to land in Amsterdam. Nine people were killed and 120 injured. An investigation found that one of the plane's altimeters, which measures altitude, had fed incorrect information to the plane's computers.

That, in turn, caused the auto-throttle to reduce speed to a dangerously slow level so that the plane lost lift and stalled. Dutch investigators described the flight's three pilots' "automation surprise" when they discovered the plane was about to stall. They hadn't been closely monitoring the airspeed.

Last month, French investigators recommended that all pilots get mandatory training in manual flying and handling a high-altitude stall. The recommendations were in response to the 2009 crash of an Air France jet flying from Brazil to Paris. All 228 people aboard were killed.

An investigation found that airspeed sensors fed bad information to the Airbus A330's computers. That caused the autopilot to disengage suddenly and a stall warning to activate.

The co-pilot at the controls struggled to save the plane, but because he kept pointing the plane's nose up, he actually caused the stall instead of preventing it, experts said. Despite the bad airspeed information, which lasted for less than a minute, there was nothing to prevent the plane from continuing to fly if the pilot had followed the correct procedure for such circumstances, which is to continue to fly levelly in the same direction at the same speed while trying to determine the nature of the problem, they said.

In such cases, the pilots and the technology are failing together, said former US Airways Capt. Chesley "Sully" Sullenberger, whose precision flying is credited with saving all 155 people aboard an Airbus A320 after it lost power in a collision with Canada geese shortly after takeoff from New York's LaGuardia Airport two years ago.

"If we only look at the pilots - the human factor - then we are ignoring other important factors," he said. "We have to look at how they work together."

The ability of pilots to respond to the unexpected loss or malfunction of automated aircraft systems "is the big issue that we can no longer hide from in aviation," said Bill Voss, president of the Flight Safety Foundation in Alexandria, Va. "We've been very slow to recognize the consequence of it and deal with it."

The foundation, which is industry supported, promotes aviation safety around the world.

Airlines are also seeing smaller incidents in which pilots waste precious time repeatedly trying to restart the autopilot or fix other automated systems when what they should be doing is "grasping the controls and flying the airplane," said Bob Coffman, another member of the FAA pilot training committee and an airline captain.

Paul Railsback, operations director at the Air Transport Association, which represents airlines, said, "We think the best way to handle this is through the policies and training of the airlines to ensure they stipulate that the pilots devote a fair amount of time to manually flying. We want to encourage pilots to do that and not rely 100 percent on the automation. I think many airlines are moving in that direction."

In May, the FAA proposed requiring airlines to train pilots on how to recover from a stall, as well as expose them to more realistic problem scenarios.

But other new regulations are going in the opposite direction. Today, pilots are required to use their autopilot when flying at altitudes above 24,000 feet, which is where airliners spend much of their time cruising. The required minimum vertical safety buffer between planes has been reduced from 2,000 feet to 1,000 feet. That means more planes flying closer together, necessitating the kind of precision flying more reliably produced by automation than human beings.

The same situation is increasingly common closer to the ground.

The FAA is moving from an air traffic control system based on radar technology to more precise GPS navigation. Instead of time-consuming, fuel-burning stair-step descents, planes will be able to glide in more steeply for landings with their engines idling. Aircraft will be able to land and take off closer together and more frequently, even in poor weather, because pilots will know the precise location of other aircraft and obstacles on the ground. Fewer planes will be diverted.

But the new landing procedures require pilots to cede even more control to automation.

"Those procedures have to be flown with the autopilot on," Voss said. "You can't afford a sneeze on those procedures."

Even when not using the new procedures, airlines direct their pilots to switch on the autopilot about a minute and a half after takeoff when the plane reaches about 1,000 feet, Coffman said. The autopilot generally doesn't come off until about a minute and a half before landing, he said.

Pilots still control the plane's flight path. But they are programming computers rather than flying with their hands.

Opportunities to fly manually are especially limited at commuter airlines, where pilots may fly with the autopilot off for about 80 seconds out of a typical two-hour flight, Coffman said.

But it is the less experienced first officers starting out at smaller carriers who most need manual flying experience. And, airline training programs are focused on training pilots to fly with the automation, rather than without it. Senior pilots, even if their manual flying skills are rusty, can at least draw on experience flying older generations of less automated planes.

Adding to concerns about an overreliance on automation is an expected pilot shortage in the U.S. and many other countries. U.S. airlines used to be able to draw on a pool of former military pilots with extensive manual flying experience. But more pilots now choose to stay in the armed forces, and corporate aviation competes for pilots with airlines, where salaries have dropped.

Changing training programs to include more manual flying won't be enough because pilots spend only a few days a year in training, Voss said. Airlines will have to rethink their operations fundamentally if they're going to give pilots realistic opportunities to keep their flying skills honed, he said.

[rudderrudderrat]

@Clandestino,
Let me see.... you pull the stick and are shouted at that you are about to stall for 54 seconds, at least two (and probably three) airspeeds are agreeing and going down, eventually pitch is positive yet the altimeter is unwinding. Somehow you conclude that all those are not clues enough that you're stalled. I am at loss to explain this. Would you, please?

Page 76.
"Until the end of the flight, the angle of attack values became successively valid and invalid. Each time that at least one value became valid, the stall warning triggered, and each time that the angles of attack were invalid, the warning stopped. Several nose-up inputs caused a decrease in the pitch attitude and in the angle of attack whose values then became valid, so that a strong nose-down input led to the reactivation of the stall warning. It appears that the pilots then reacted by a nose-up input, whose consequences were an increase in the angle of attack, a decrease in measured speeds and, consequently, the cessation of the stall warning."

So you think stopping the stall warning when airborne and IAS<60kts clarified their situation?

[DozyWannabe]

So you think stopping the stall warning when airborne and IAS<60kts clarified their situation?

You're poking at cross tortoises* with that statement and I think you know it. The fact is that you are both talking about very different phases of the accident sequence. You're referring to a later event, where the <60kts stall warning inhibition may have worked counterintuitively, and that's a fair appraisal and reasonable point. Clandestino is referring to the point just after the apogee where the stall warning is functioning and the partial IAS, altimeter and attitude indicator were all giving readings that when combined should logically indicate to an airman that their aircraft is either approaching stall or indeed stalled, and that this went on for nearly a minute without apparent corrective action by the crew before the <60kts inhibition even came into it - as such, he's also made a fair appraisal and has a good point.

* - Best Spoonerism ever IMO...

[Machinbird]

@Clandestino,
Quote:
Let me see.... you pull the stick and are shouted at that you are about to stall for 54 seconds, at least two (and probably three) airspeeds are agreeing and going down, eventually pitch is positive yet the altimeter is unwinding. Somehow you conclude that all those are not clues enough that you're stalled. I am at loss to explain this. Would you, please?Simple.
0200 mindfog, automation overdependence and atrophied/inadequate emergency skills resulting in failure to see the forest for the trees.

A competent pilot, faced with an emergency, should be looking for the big picture. You have to throw out the chaff to form the big picture. If you live with years of routine operations, it is too easy to end up just staring at an indication that is lying or unhelpful. You need to scan, scan, scan until you build a sensible big picture, and until you do, it is very easy to form a faulty picture. This is a demanding mental activity and fatigue can cripple your mind.

When the Fit hits the Shan, you have to rev up your brain first. The normal inflight slog does not work. A little adrenaline can be helpful. An excess of adrenaline can greatly interfere. The difference between these two states results from your learned response to emergencies. You have to learn how to control your own body.

I remember a 4 plane formation flight when I was a student that inter-meshed with a 2 plane flight going at a 90 degree heading to ours. An adrenaline kick resulted of course, but I just told myself-"The emergency is over, no need to get excited." and it worked. Managing/controlling the adrenaline response is one of the skills you have to develop, but I think you get precious little opportunity in the majority of airline flying.

I would imagine that the Abidjan A310 accident lessons have factored into the stall warning design on the later 'Busses. ASN Aircraft accident Airbus A310-304 5Y-BEN Abidjan-Felix Houphouet Boigny Airport (ABJ) (http://aviation-safety.net/database/record.php?id=20000130-1) although It still seems possible to have a similar incorrect stall warning on the current machines.
I see no reason for stall warning to be inhibited at any airspeed with weight off the wheels. That has to be a mistake. As I have said before, AOA is primary flight information, and should not be inhibited by another type of primary flight information.
Similarly, autotrim must not trim into a stall. Even the test pilots avoid doing that if they can-it is too hazardous.

[rudderrudderrat]

Hi DozyWannabe,

The two co-pilots didn't hear / recognise / believe / admit (any of those) the stall and insisted on applying TOGA 15 degs pitch throughout the stall warning.
When the Captain arrived on the flight deck, the stall warning ceased because IAS<60 kts. If it had continued - then maybe he would have diagnosed the problem correctly.

To prevent a similar accident, is your solution to simply change the crew?
I think BEA will arrive at a different conclusion.

Edit. Please explain how you think it is possible for a heavy aircraft to be airborne, yet travel through the air with a speed <60 kts.

@machinbird.
I agree.
Here is an example where the crew acted correctly.
BA 747 crew commended for escaping near-stall on take-off (http://www.flightglobal.com/articles/2010/06/26/343738/ba-747-crew-commended-for-escaping-near-stall-on-take-off.html)

[cwatters]

It may be a 'hypothetical' but almost every other aircraft in the world would use the undercarriage 'squat switch'.

Perhaps it does use the squat switch to disable the alarm on the ground? It could do that and still disable it at <60kts in the air for another reason.

[jcjeant]

Hi,

Perhaps it does use the squat switch to disable the alarm on the ground? It could do that and still disable it at <60kts in the air for another reason. Of course it was for another reason
The engineers knew very well that an actual speed below 60 knots was impossible (or almost improbable) .. but it could come from a false indication given by the pitot tube
The engineers knew very well that, pitot tubes were not reliable in some flight areas (giving false information)
And even it is not the reason ...for me .. the failure of the engineers is not in the design of the global Airbus flight control system .. but their failure is that not fixing one of the most important measuring device (pitot tube) who collect very important information for feed their sophisticated system
A reliable speed measuring device will never indicate 60 knots or less .. provided you are not in a certain flight condition (a stall is one )

[DozyWannabe]

Hi DozyWannabe,

The two co-pilots didn't hear / recognise / believe / admit (any of those) the stall and insisted on applying TOGA 15 degs pitch throughout the stall warning.

That would appear to be the case based on what we know so far - though it certainly doesn't look like the PNF agreed with the PF's decision based on the CVR traces.

When the Captain arrived on the flight deck, the stall warning ceased because IAS<60 kts. If it had continued - then maybe he would have diagnosed the problem correctly.

Well, it was sounding for a few seconds after he arrived and it's probable that he heard it through the flight deck door for some time before he arrived - so while your point is valid, I don't think that deriving "woulda-coulda-shoulda" points is helpful in this case. It's definitely not a positive factor in the stall warning design logic, but you have to ask yourself whether the logic was reasonable given the knowledge and state-of-the-art at the time. This was, after all, the first time that anything of this nature had happened. As it is, the Captain was summoned from trying to get to sleep, so it's probably fair to say that his faculties weren't at their best.

To prevent a similar accident, is your solution to simply change the crew?

Not at all - frankly I find it quite saddening when people say that I'm trying to "blame the crew" and leave it at that.

Edit. Please explain how you think it is possible for a heavy aircraft to be airborne, yet travel through the air with a speed <60 kts.

I don't think it'd be easy or desirable - and I think that's probably why the systems were designed the way they were - for the very reason that it is so unlikely.

Here is an example where the crew acted correctly.
BA 747 crew commended for escaping near-stall on take-off (http://www.flightglobal.com/articles/2010/06/26/343738/ba-747-crew-commended-for-escaping-near-stall-on-take-off.html)

And ironically that was due to a software logic error in the 744's systems that had never reared its head until that moment.

[Lyman]

With a descent rate up to ~10000+ fpm, and its attendant airstream howl, STALLWARN is not a good candidate for a conclusion of airframe STALL. They are not consistent, and in fact, the PF remarks re: the "crazy speed", something not generally associated with STALL.

One might assume it was this airmass din that caused all three PILOTS to "miss" the aerodynamic STALL? It is the likeliest of possibilities, imo.

With "good" ROLL control, more evidence still the airframe was "flying".

Further, the ROD could be thought to be indicative of a dive, given these other cues, and eventually, they acted on it too: "Tire, Tire, Tire...."

Captain's suggestion earlier of "Pull" was met with "But I have had Full back for some time..." A defensive statement, to mean perhaps, 'but I have been trying to exit this dive....' (a conjecture) etc.

So in sum, not a complete mystery why the crew didn't believe she was STALLed?

I think far too much is made of the lack of STALL recovery attempts on the way down.

I also believe far too little attention is paid to the reasons the a/c climbed into the STALL. It is this climb that killed her.

[jcjeant]

Hi,

DW
As it is, the Captain was summoned from trying to get to sleep, so it's probably fair to say that his faculties weren't at their best.
2H 01min 46 Captain leave flight deck
2H 11min 42 Captain again on flight deck

Lost of faculties in 10 minutes .. cause out of ... a deep sleep :confused:
I'm sure he never hit the sack
Think again and repost about ....

Lyman
With "good" ROLL control, more evidence still the airframe was "flying".I'm not so sure that the roll was so much controled by the PF or PNF(see the mayonnaise resulting of the "control" .... )

Lyman
I also believe far too little attention is paid to the reasons the a/c climbed into the STALL. It is this climb that killed her. Indeed if in the first place the PF had paid more little attention .. maybe he had not put the a/c into the stall

rudderrudderrat
To prevent a similar accident, is your solution to simply change the crew? Better was not this crew in the first place (not trained)
Anyways AF had not better crew (all the AF crew were not trained for this event)
Waiting 228 loss of life for make change (better training) .. is way too much cost IMHO
BTW .. AF shares are also in a "deep stall" and seem's that AF stay also pulling on the stick ..... as they do not understand what is happening ..
French taxpayers will have to open their wallet .. :)

[rudderrudderrat]

Hi DozyWannabe,

Thanks for the reply - I think we are talking at crossed tortoises.
Quote:
Me.... Please explain how you think it is possible for a heavy aircraft to be airborne, yet travel through the air with a speed <60 kts.

You .... and I think that's probably why the systems were designed the way they were - for the very reason that it is so unlikely.

Do we agree that it is impossible for a passenger airliner to be at FL 350 with an airflow <60kts passing over the Alpha probes (from whatever direction)?

The A330 stall warning logic has an error (similar to the B744 slat retract & hence stall warning on take off, which I mentioned earlier). The 744's stowing the inboard leading edge devices due to a spurious REV signal when airborne, should also have had on ground logic to prevent it. And ironically that was due to a software logic error in the 744's systems that had never reared its head until that moment.

AB stall warning inhibit below 60Kt should apply only on the ground.

[Lyman]

jcjeant

My reference was to ROLL response of the a/c (seen in the traces), a positive feedback to the pilots of controlled flight, and not STALL.

[HazelNuts39]

Do we agree that it is impossible for a passenger airliner to be at FL 350 with an airflow <60kts passing over the Alpha probes (from whatever direction)?No, I don't agree. In dynamic maneuvers the airspeed can attain any value, including negative values.
AB stall warning inhibit below 60Kt should apply only on the ground.Let's be clear about this. The stall warning is not inhibited, but the AoA signal becomes invalid (no computed data) below 60 kt. It is logical that this occurs at a certain low airspeed, because as the air speed reduces, the friction in the vane mechanism becomes more significant compared to the aerodynamic force that points the vane in the right direction, and the output value becomes increasingly inaccurate. However, IMHO when stall warning is active it should not stop when the AoA becomes invalid but should continue to sound until a valid AoA signal indicates an AoA value less than the stall warning threshold value.

[Machinbird]

Do we agree that it is impossible for a passenger airliner to be at FL 350 with an airflow <60kts passing over the Alpha probes (from whatever direction)?

Heck no! All you need is a bit of ballistic trajectory and any value is possible.
Any AOA sensor that requires 60 knots to read local airflow direction should be trashed. That criterea is way too high. I tested several former airline and military AOA transmitters a while ago by sticking them out the car window and noting my 'ground speed'. They were alive by 15 to 20 mph.

HN39

IMHO when stall warning is active it should not stop when the AoA becomes invalid but should continue to sound until a valid AoA signal indicates an AoA value less than the stall warning threshold value.


I agree fully. Just have a procedure so that you can kill an AOA sensor in case you learn while airborne that someone rammed it with a baggage cart or that it is frozen. With multiple sensors onboard, you do have redundancy. It is quite possible to detect and report sticky AOA motion with an arrangement such as the Airbus has. That is a design feature that Airbus needs to look at. How long was AF447's #1 AOA sensor sticky? A day? A month? A year? Who knows?

My biggest beef with the Airbus ADR design is very fundamental. Airspeed indications should not influence AOA indications in any way. They are fully independent parameters. Why allow one defective parameter to silence a good one?

[Lyman]

Hazelnuts 39

To the extent that "inhibit" certainly means "by design", in your reply, let's look at the problem.

"By Default only", the STALL system is inop. Due other problems, in other words.

Rather than exonerate a failure of the STALL WARNING SYSTEM to continue, does it not instead point to the lack of a design consideration for a demonstrably critical potential FAULT?

Not only does it cast a suspicion of inattention at the design level, it shows a fundamental flaw in the understanding of the consideration itself.

[DozyWannabe]

However, IMHO when stall warning is active it should not stop when the AoA becomes invalid but should continue to sound until a valid AoA signal indicates an AoA value less than the stall warning threshold value.

I'm sure that is the idea that will underpin the eventual logic change requested by the BEA. However, as a logic guy I feel compelled to point out why it isn't necessarily that simple. Changing any logic path will have various side-effects that were not previously considered, and factors that will need to be taken into account include the mean-time-to-failure of the components, including the AoA vanes themselves (because theoretically you could have a mechanically-failed AoA vane causing a false stall warning to remain sounding even if the remaining pair are experiencing only a transitory failure). Ultimately it's a question of probabilities and statistcs that I freely admit is a weak point in my mathematical understanding.

[Lyman]

Likewise a consideration of the effects of ill considered, or even well addressed, changes. As in, PITOT PROBE fail. What is the logic behind a UAS recovery being well addressed, and an AoA Vane which causes false STALL being not addressed?

To some of us, closing the corral gates after the Horses have bolted is not good practice, though compelled by the "Logic Failure"?

"If it breaks, we'll fix it"? "If it fails, we'll replace it?"

These are not complicated shortcomings; their simplicity does not meld well with the complexity used to address them.

Without taking a side, the HSP profile seems to be rather congruent with the initial 447's climb. All Nose Up, no down, and a crazy climb.

[Mr Optimistic]

As I understand it the underlying reason isn't to inhibit the stall warning below 60 it's to prevent spurious data when the airflow is outside the vanes spec. Stalled or not stalled, a warning that airspeed is less than 60 knots when there is no weight on the wheels would be equivalent. If that situation can only arise when stalled, then fair enough allow a warning. Seems quixotic to cancel an existing warning when the speed goes out of range and it is likely that that very same stall caused the speed to go out of range.

[Machinbird]

Dozy, You are overthinking this. The engineers are going to have to get involved and chase down all the new logic branches and implications.

They started with a bad premise the first time. That AOA was a function of Airspeed and other parameters. It is really an independent variable.

[DozyWannabe]

The engineers are going to have to get involved and chase down all the new logic branches and implications.

This is true, but...

Dozy, You are overthinking this.

I can assure you I am not. Part of the reason my old Prof was so leery of computer controlled and managed aircraft in the first place was the sheer amount of complexity required to cover, if not all eventualities, then at least a significant majority of them - and then regression-test the software and hardware to prove reliability to a level required by aviation regulations. Remember this was the '80s - when every line of code had to count, and the hardware specifications called for technology that was obsolete even by the standards of the time.

His visit to Toulouse left him impressed with the lengths that they had gone to to do so, and he worked that into the things he taught us, but even with all that he remained neutral on the subject. I'm slightly more sanguine than he was, but that does not mean that I'm naive to the possibility of problems.

They started with a bad premise the first time. That AOA was a function of Airspeed and other parameters. It is really an independent variable.

But we do not know they started with that premise - all we know is how the eventual design ended up. Given what I was taught, the design is likely to be the way it is probably for a very good reason. What we have here is an edge case where that design decision may not have helped matters. What we don't know is the number of times where that design decision may have helped in a situation where the flight envelope was not compromised in such an extreme manner.

[rudderrudderrat]

What we don't know is the number of times where that design decision may have helped in a situation where the flight envelope was not compromised in such an extreme manner.
That will be all the false stall warnings received at 59 kts and below.

[DozyWannabe]

That will be all the false stall warnings received at 59 kts and below.

Check HazelNuts39's very important point above. Stall warning inhibition is not a direct outcome of the logic, it is a side-effect of the logic that says AoA data is unreliable. Put simply, the logic does not say "if airspeed < 60kts, inhibit stall warning", it says "if airspeed < 60kts then AoA data is unreliable". So already the scope for positive effects from the logic has increased (whenever AoA vanes have headed south due to contamination/mechanical failure in the past, for example).

Up until this incident happened, I think most would agree that the chances of an airliner stalling so comprehensively from cruise that it did actually reach the point where AoA data could become invalid were suitably remote, and that this logical side-effect would pose no threat to flight safety. Now it has been proven that it *is* possible, the logic needs looking at.

[jcjeant]

Hi,

What we don't know is the number of times where that design decision may have helped in a situation where the flight envelope was not compromised in such an extreme manner. Personnaly I prefer work with what I know ... instead with what I don't know..
What I know is that the AF447 ended in the sea and it's possibly an (minor) design implication to add to the fact (major) of the incapacity of the pilots to fly the plane in a professional way ... (pilot error or unconscious action)

[Lyman]

I'm sure the logic was well looked at, and proposing that it need be scrutinized now, is misleading the herd. Perhaps another look, then?

Once STALLED, allowing the cessation of the WARNING is inexcusable, by any stretch. Perhaps disabling all but the few critical prompts (and certainly the ECAM) might be a start.

[DozyWannabe]

Personnaly I prefer work with what I know ... instead with what I don't know..

Me too (along with most rational people, one would hope!). What I'm saying is that until we know the reasoning behind the logic tree, we need to be careful about making snap decisions over the changes we'd like to see applied. Right now we're talking about a single accident among tens if not hundreds of thousands of safe flights made by the A330 over its service life and the risk is that making a change based on a single incident without properly identifying the potential consquences of that change could make the type less safe rather than more.

Once STALLED, allowing the cessation of the WARNING is inexcusable, by any stretch.

20/20 hindsight is a wonderful thing, but the problem here is that the aircraft was so far outside of the flight envelope by the time the stall warning stopped that the very devices used to calculate the data used for stall warning were considered to be unable to generate reliable data.

Look at the response on here when the initial flight recorder data was released - most pilots were in a state of stunned disbelief that a professional crew could have put the aircraft in that state - it's not a major leap of imagination to suggest that the engineers and designers were equally incredulous both before and after the incident.

Perhaps disabling all but the few critical prompts (and certainly the ECAM) might be a start.

But that's the very reason the systems are designed the way they are - i.e. to logically separate out any spurious warnings. The ECAM tells the pilots what is wrong with the aircraft - what good would disabling that do?

We're in danger of losing sight of the fact that the stall warning operated correctly for some time after the aircraft had departed from it's certified envelope. No amount of fiddling with the logic at the extreme level of the envelope excursion concerned can alter the fact that the warning was not heeded, and right now there's no evidence that any of the crew were distracted by any other noises or displays.

[Lyman]

A (very) large red Herring. The critical data involves the total of UAS incidents (accident) and the HSP altitude excursions, plus other identified anomalous unsafe conditions. If we start to add in the degradation of flying skills at altitude and other locales, we have a distressing snapshot of the status quo, to include other manufacturers, to be sure.

Beware the statistical distraction. Its purpose is not to emphasize safety, but to disguise the lack thereof, imho.

[Mad (Flt) Scientist]

I'll just comment that there's no easy way to flag data as reliable enough for some purposes, while unreliable for others.

A FBW system using alpha as part of the control laws is rather more sensitive to AOA accuracy than a conventional type 9which frankly hardly cares until you get to low speeds where the AOA should be doing stuff). i *suspect* - and I confess its nothing more than a semi-educated guess - that one of the reasons for declaring AOA invalid at low airspeed was that the AOA vane could not be stated to provide the required accuracy at such low speeds, and that this accuracy was specified in the context of normal law operations. Gross AOA, good enough to fire the shaker, wouldn';t be good enough to drive the FBW laws.

Now, you could say "ah, but you can't be in normal law at such low speeds" - and normally that'd be correct. But the design was probably trying to cover all bases, but with the assumption that defending the normal law scenario against erroneous and dangerous AOA data was the more important thing to do.

Now, with hindsight, we might try to provide for discarding the AOA data for the control loop closure, while retaining it for the warning. But that's also complexity - and the golden rule in designing complex systems is to not make them any more complex than they need be. Judging the point of "need be" is the trick, of course.

[Lyman]

Dozy is correct, in that the discussion is at the tail end of a long sequence of remarkably disintegrating cruise flight.

At STALL, there is no reason to suspect the a/c format of anything untoward; save the fact that two, and eventually three pilots disregarded what should have been a butt puckering cacophony rather than a demure SyntheticVoice in concert with a child's click toy.

Harsh? What is it to be, then, for a lack of recognition of the death rattle of a two hundred million dollar a/c with 228 sob? No comment? Nuttin?

Incredulity remains. There is more to this than meets the eyes. Perhaps the clamor for better pilots is a response to what may be something that is utterly unbelievable on its face.

None of what is offered as explanation or redress is acceptable. None.

Will this come clear? Will the record be complete, and be made public?

[Machinbird]

Dozy, you are overthinking this.


I can assure you I am not. Part of the reason my old Prof was so leery of computer controlled and managed aircraft in the first place was the sheer amount of complexity required to cover, if not all eventualities, then at least a significant majority of them - and then regression-test the software and hardware to prove reliability to a level required by aviation regulations. Remember this was the '80s - when every line of code had to count, and the hardware specifications called for technology that was obsolete even by the standards of the time.

Dozy, we are not flying with the first design of Airbus 330 control laws nor even the second.

The software design is a work in process.

Airbus has an extensive protocol and infrastructure for maintaining flight control software. At this point, it is an engineering problem and capable of being handled without more than the usual superhuman effort.:}

Mad Scientist.
Doesn't C* use 'g' for control loop closure at high speeds and body angle at low speed?

[CONF iture]

http://i45.servimg.com/u/f45/11/75/17/84/af447_11.png (http://www.servimg.com/image_preview.php?i=100&u=11751784)

Airbus documentation is simply false.

If the CAS measurements for the three ADR are lower than 60 kt, the angle of attack values of the three ADR are invalid (NCD status) and the stall warning is then inoperative. This results from a logic stating that the airflow must be sufficient to ensure a valid measurement by the angle of attack sensors, especially to prevent spurious warnings on the ground.
What a ridiculous pseudo reason really !

Those AoA vanes move at nothing. I took the opportunity to manipulate them the other day and 15kt of relative wind is probably already in excess to place them in the wind on. No wind on them, they also stay in the position you place them, like absolutely not affected by gravity.

[jcjeant]

Some documentations ....

AirbusPapers.pdf (http://www.mediafire.com/?awwddk9a4hkd3nu)

[BOAC]

Now, with hindsight, we might try to provide for discarding the AOA data for the control loop closure, while retaining it for the warning. But that's also complexity - and the golden rule in designing complex systems is to not make them any more complex than they need be. Judging the point of "need be" is the trick, of course. - Whoa! Isn't that going to deny any AoA 'protection' unless you inhibit it only in normal law?

[glad rag]

Good read that.

Remembering the title is Operational Philosophy, the devil will be in the detail, or more precisely, lack of knowledge/practice off, which is becoming more and more obvious in the case of AF447.

[Clandestino]

Simple.

0200 mindfog, automation overdependence and atrophied/inadequate emergency skills resulting in failure to see the forest for the trees.I agree. I couldn't find crew's operating history on days prior to accident. If capt and senior F/O had 24 hours layover in Rio, their clock would be still on CET and that would put the time of the accident at just past the middle of the circadian low, at 4AM. What effect on the junior F/Os body clock had the alleged R&R in Rio, remains to be seen.

I would imagine that the Abidjan A310 accident lessons have factored into the stall warning design on the later 'Busses although It still seems possible to have a similar incorrect stall warning on the current machines. Stall warnings gave unwarranted warnings on older types too, like L1011 at KJFK in '92 (http://aviation-safety.net/database/record.php?id=19920730-0). Fortunately, outcome was less messy. Try hard as we might, we'll never make perfect and infallible stall warning system. Best we can hope for is good enough system combined with good enough crew and hope that system's and crew's low don't overlap. EK Gann understood it very well and to say that much has changed from his times would be displaying very shallow understanding of the aviation.

Similarly, autotrim must not trim into a stall.

Hmmm.... inhibiting autotrim when stall warning is present, like it's inhibited in high speed protection? Interesting idea which might have some merit. While I currently can't think of any reason why it shouldn't be so, so far AF447 investigation has not uncovered a single reason why autotrim wouldn't work with pilots input. If pilots pushed forward, which is universally accepted as good idea when faced with upright stall, THS would follow.

Airbus documentation is simply false.

(quote from interim3, page 20)

What a ridiculous pseudo reason really !

Those AoA vanes move at nothing. I took the opportunity to manipulate them the other day and 15kt of relative wind is probably already in excess to place them in the wind on. No wind on them, they also stay in the position you place them, like absolutely not affected by gravity.

Parbleu, monsieur! You have managed to invalidate calculations of Airbus engineurs which were accepted by certifying authorities on your own by conducting a simple manual experiment. I assume you've done it single-handedly. Congratulations... not! Do you have any idea what's the difference between dynamic pressure at 60 KEAS and 330 KEAS, everything else being identical? Only when you calculate it, we can discuss about precision and reliability of AoA vanes under all conceivable operational circumstances and whether would be too much of designers to come with those working under inconceivable ones.

[Lyman]

Minor point re: STALL WARNING. There was nothing whatever wrong with it, it functioned correctly. What failed happened later, and focusing on the lack of a Horn when one minute into LOC is like nibbling on the plastic garnish in your sushi.

Without comment, BEA does not address BUFFET. The entry into STALL was not 'conventional', and lacked a true break. That left the crew to rely on a System (SW) that was at best 50 percent dependable in the identified problem, (UAS)). That it was correct meant nothing to the crew, how were they to know?

PF was obsessed with Overspeed, and the ROD was not completely non-indicative of HS? The climb was similar in nature to an HSP ascent, and NOSE DOWN 'not responsive'?

Each time the guff gets to this point, someone needs to remind us of the conditions, the failures, and the not well understood UAS problems.

Not even BEA has condemned the crew as yet. Have they cynically relied on the public to convict?

[AlphaZuluRomeo]

Hmmm.... inhibiting autotrim when stall warning is present, like it's inhibited in high speed protection? Interesting idea which might have some merit. While I currently can't think of any reason why it shouldn't be so, so far AF447 investigation has not uncovered a single reason why autotrim wouldn't work with pilots input. If pilots pushed forward, which is universally accepted as good idea when faced with upright stall, THS would follow.
This topic was already discussed a few pages back (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-11.html#post6651335). From the FCOM:
When angle of attack protection is active, THS is limited between setting at entry in protection and 2° nose down (i.e. further nose up trim cannot be applied).
Basically, the idea was: why not do the same in Alt Law? (with the AoA protection remplaced by the Stall Warning, of course).

[NARVAL]

Lyman:Each time the guff gets to this point, someone needs to remind us of the conditions, the failures, and the not well understood UAS problems.
Exactly!
Let us try to be fair:
Simulators (Airbus test pilots have sais so) do not simulate in a useful way for training crews, piloting sensations at high altitude: that means the fact that a small stick input will give much more important nose up or down effect than at a lower altitude. How do you train then as airlines do not encourage hand flying in high altitude cruise?
Protections (although here, as we do not know exactly when the alternate law came in, this may be out of the subject) kick in with the same enthusiasm at 2000 ft and at 35000 ft in a heavy, rear centered airplane, with no regard at all for the flight envelope: see the Caracas A340 incident.Unbeliavable to me: you may have a 1,75 positive g "protection" at 39000 ft!
Speed indications coming back but not trusted. Understandable.
No AOA indicator. (I flew with one in the A300 for years, and, believe me, it is useful).
Nose up from 0 to max 10 degrees, variable, with an angle of attack (unknown to the pilots) of 40 degrees! Difficult to guess for them that their AOA is so high.
Trim wheel: never looked at, never used manually in thousands of hours..
Variometer unreadable in those planes, when leaving "normal values" and probably not read in the chaos.
Only the altimeters unwinding at full speed were an indication of what was really happening to them. I do not say they did very well. I say, without doubt, that they were not test pilots and that the situation was totally out of reach of the training they were provided.
Their experience was onlyA320 A340 A320...Where would they have learnt unuasual positions ?
I have a lot of hours, and have learnt to be really modest. Let us all give a thought to the very many, distressing missing informations in the BEA report. I hope the next one will be a little more complete.

[Mr Optimistic]

As I understand it the underlying reason isn't to inhibit the stall warning below 60 it's to prevent spurious data when the airflow is outside the vanes spec. Stalled or not stalled, a warning that airspeed is less than 60 knots when there is no weight on the wheels would be equivalent. If that situation can only arise when stalled, then fair enough allow a warning. Seems quixotic to cancel an existing warning when the speed goes out of range and it is likely that that very same stall caused the speed to go out of range.

Hope it's allowed to quote myself when I subsequently disagree. After a bit more thought I would give the designers some slack on this. Reasonable (and correct in this instance) to think that the stall warner would have done its job as best it could, well before speed decayed to 60knots. Can't blame the messenger if no-one gives it credence. My supposition is that it was discounted when it was real the first time round but believed when it reactivated on ND.

[OK465]

Simulators (Airbus test pilots have sais so) do not simulate in a useful way for training crews, piloting sensations at high altitude

The approved flight data package that is used by the simulator manufacturers comes from Airbus. It includes automated tests utilized to periodically check & assure that the simulator is performing consistent with the actual data accumulated from flight testing within the aircraft operating envelope, at any altitude.

Why would company test pilots make a statement like this?

[xcitation]

Does anyone have a comment on the fact the PF (right seat) was found with lap belt undone and his audio channel sounding like he hit his mic on a wall? This correlates with the maxima of the acceleration graph on page 43 (+ 1.15g up).
Anyone know if AF pilots always fly with restraints attached or treat them in a casual manner? I could not find the AF policy for pilot seat belts.

On the right side seat no belt was attached.

Moreover, there is a noise on track 1 of the CVR, at about 2 h 10 min 55, which might be the impact of the microphone striking a wall, heard at a stable frequency.

[Mad (Flt) Scientist]

The approved flight data package that is used by the simulator manufacturers comes from Airbus. It includes automated tests utilized to periodically check & assure that the simulator is performing consistent with the actual data accumulated from flight testing within the aircraft operating envelope, at any altitude.

Why would company test pilots make a statement like this?

Because the simulator "matches where it touches" - it reproduces the manoeuvres specified by the data provided, and not necessarily any other manoeuvre. In practice, sims do better than that minimum, because the manoeuvres matched do cover reasonable variety of manoeuvres and across a fair bit of the envelope.

But go far outside the envelope of the specific manoeuvres and you are on your own. I suspect that is what the test pilot statement likely alludes to.

[infrequentflyer789]

http://i45.servimg.com/u/f45/11/75/17/84/af447_11.png (http://www.servimg.com/image_preview.php?i=100&u=11751784)

Airbus documentation is simply false.


No, just too simple. Possibly lost something in translation also. It should be perfectly obvious, with only a small amount of thought, that the warning cannot possibly be permanent if AOA is not recovered.

[infrequentflyer789]

This topic was already discussed a few pages back (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-11.html#post6651335). From the FCOM:
When angle of attack protection is active, THS is limited between setting at entry in protection and 2° nose down (i.e. further nose up trim cannot be applied).
Basically, the idea was: why not do the same in Alt Law? (with the AoA protection remplaced by the Stall Warning, of course).

Possibly (guessing a bit) because in Alt Law you're there because things are broken, and therefore airdata (for one) may not be assumed to be as reliable.

There is a difference between giving pilots a warning (which may be ignored...) and taking affirmative action to limit or override the pilot. The latter should requrie a higher degree of confidence in the data you are acting on - and that may not be available in Alt-Law.

[Lyman]

xcitation. Without too much comment, there is a possibility nomenclature is not being understood. "On the right, 'side seat' (#4)", there was no belt attached. This may mean there was no remnant of belt attached to the seat frame. It would not mean there was no belt attached to a body, since without restraint, there would be no body remaining attached to the seat frame. BEA would ordinarily identify each seat by number, and RHS would be #2.

You say they identify "his mic". Not necessarily. They say "the mic". This could mean the ambient mic (one of, eg).

Either way, having found no belt attached to the seat, strictly speaking, it means that the belts were lost from their attachments (at impact?).

[infrequentflyer789]

Because the simulator "matches where it touches" - it reproduces the manoeuvres specified by the data provided, and not necessarily any other manoeuvre. In practice, sims do better than that minimum, because the manoeuvres matched do cover reasonable variety of manoeuvres and across a fair bit of the envelope.

But go far outside the envelope of the specific manoeuvres and you are on your own. I suspect that is what the test pilot statement likely alludes to.

The original post clarified (cut from the quotes):

that means the fact that a small stick input will give much more important nose up or down effect than at a lower altitude.

i.e. claiming the real thing is a lot twitchier than the sim.

It shouldn't be - ample data should be available for that, and if that statement is true, I would say the sims need fixing.

[BWV 988]

Having read most posts since the recovery of the recorders, and coming from a medical-statistical background, DozyWannabe in #833 raises an important issue:

What we have here is an edge case where that design decision may not have helped matters. What we don't know is the number of times where that design decision may have helped in a situation where the flight envelope was not compromised in such an extreme manner.

When checking for errors/illnesses, the false negative type is typically the one that gets most attention, while false positive alarms may be more harmful in the long run.

False negative in this case would mean not to report a stall, that is indeed happening, while false positive would be to report one that isn't there. A false positive alarm is a cry wolf, insensitizing pilots to a particular warning. The "shut up gringo" incident, the tripped circuit braker on NW255 and (maybe) AF447 reactions are indications of this happening.

Actual stalls are very rare, so even though a system may have a low propabilty of reporting false positive, that scenario is still more likely than a real stall (true positive). In general, minimizing both types of errors may not be so simple, and lowering one type can lead to a rise of the other one.

[TyroPicard]

@Lyman...
Not even BEA has condemned the crew as yet.

And nor will they. From their homepage...

The sole objective of the technical investigation is to collect and analyze useful information, to determine the circumstances and the certain or possible causes of the accident or incident and, if necessary, to make safety recommendations in order to prevent future accidents and incidents.

[Lyman]

TyroPicard, re: "objective"

Except when it becomes necessary to support a manufacturer with a Press Release, and in doing so, laying Blame on crew by default. That Press release was a complete embarrassment, and an abdication of the very charge you quote.

A Mission Statement can be a promise made in Haste, prior to the challenge of the Real World.

The responsibility of those who are served is to challenge the Mission.

Them's the 'Rules'.

[CONF iture]

No, just too simple. Possibly lost something in translation also. It should be perfectly obvious, with only a small amount of thought, that the warning cannot possibly be permanent if AOA is not recovered.
Why not ???

To the contrary, it is paramount the warning does not quit before the stall exit is complete. More than a question of regulation, it is a question of common sense.

But I’m curious here : When would you stop it otherwise ?

[CONF iture]

Do you have any idea what's the difference between dynamic pressure at 60 KEAS and 330 KEAS, everything else being identical?
AFAIK 'dynamic pressure' applies on both side of the vane ... but please tell me more.

[rudderrudderrat]

Hi CONfiture,

I think IF789 was joking at the language translation.

If you are stalled, then the warning can not possibly be permanent, because if AOA is not recovered, then the crash would stop it.

[AlphaZuluRomeo]

Possibly (guessing a bit) because in Alt Law you're there because things are broken, and therefore airdata (for one) may not be assumed to be as reliable.
Yes, but perhaps it should be a good idea to have a stall warning, even if the IAS is NCD / < 60kt.
If you have a NCD / invalid AoA... well... I don't know. But that's not the point.

There is a difference between giving pilots a warning (which may be ignored...) and taking affirmative action to limit or override the pilot. The latter should requrie a higher degree of confidence in the data you are acting on - and that may not be available in Alt-Law.
I totally agree with you, here.
But I was not proposing to limit or override the pilot, but to limit nose up autotrim.
I cannot imagine a situation where it would be dangerous not to autotrim nose up, when stall warning is ON:
- if the stall warning is correct (i.e. most of the cases), one would not trim up, but lower the nose
- if the stall warning is incorrect (e.g. wrong AoA sensed...) => false positive:
---> would it be a problem/dangerous to inhibit autotrim NU? (note: manual trim always possible)
---> is this scenario likely versus the above one?

[DozyWannabe]

Except when it becomes necessary to support a manufacturer with a Press Release, and in doing so, laying Blame on crew by default. That Press release was a complete embarrassment, and an abdication of the very charge you quote.

Lyman, you may be in need of a "chill pill" again. Not only was there nothing in the "note" released prior to the 3rd interim report (which is presumably what you are referring to) that was in support of the manufacturer, either explicitly or implicitly. All it said was that there appeared to be no technical or mechanical failure of the aircraft before the departure from controlled flight over and above the pitot blockage/UAS issue we already knew about.

Firstly, it's a logical fallacy to say that making a statement of that nature "lay[s] blame on crew by default" - that is simply not true, and an example of what many on here will recognise as a "false dichotomy" - a neophyte debating tactic.

Secondly, the press release did not directly lay any responsibility on the crew (nor was it a "cynical ploy" to get the public to do so). All it did was state the facts of the matter, among which was the indisputable fact that the crew appeared to mishandle the aircraft following a UAS incident, leading to a stall and loss of control. It was but one factor in the holes in the cheese/chain/graph of events that led to the accident. That the press may have oversimplified what was actually said in order to provide a more sensational story (and thus sell more papers) cannot be laid at the door of the BEA. Remember that the press have skin in the "face-saving" game here, having popularised the "baby pilot crashes aircraft" meme a couple of years back when the facts were very thin on the ground - to go back on that would make them look very foolish.

In part, it was this constant attempt to re-tread things that you have already brought up several times under several aliases that got the R&N thread closed down and transferred to Tech Log. Do you want the mods to shut down this discussion too?

[infrequentflyer789]

Why not ???

To the contrary, it is paramount the warning does not quit before the stall exit is complete. More than a question of regulation, it is a question of common sense.

But I’m curious here : When would you stop it otherwise ?


rudderrudderrat has it right.

The impact (ground/water/whatever) will stop it. Until stall exit is complete you are falling, not flying. Falling is not a permanent state (unless you are in orbit).

It is common sense that the manual cannot mean the warning is permanent without qualification.

[Lyman]

Someone is taking a disagreement a bit too far. BEA's Press Release allowed Airbus to claim no "new" issues with the a/c. That they did, and since no one was available to prompt no "New" issues with the crews, there you go. It was cynical, callous and sly, imo.

You disagree? Awesome....... A difference of opinion is healthy, up to the point where personal slander and hyperbole get slung. Not one time have I attacked you or your "chill" quotient. You seem intent on expanding ad nauseum on things not being discussed.......

A disagreement is not an insult, so there we are. You continue to have my respect and my admiration for such a complete grasp of the topic.

I tire of being "warned" that I am somehow compromising the thread.

Are you saying the thread disappeared due my posts? That would be odd, since ordinarily it is the poster who garners the ban, not the discussion, and you may have an issue not with me, but with the mods.

[DozyWannabe]

Someone is taking a disagreement a bit too far. BEA's Press Release allowed Airbus to claim no "new" issues with the a/c. That they did, and since no one was available to prompt no "New" issues with the crews, there you go. It was cynical, callous and sly, imo.

Back up a second - the BEA "note" was the first time *anyone outside of the investigation* had any idea what the crew did, so if there was no further technical failure highlighted by the flight recorders then there could be *nothing but* "'New' issues with the crew" presented. That the pitot tubes had failed and caused a UAS incident was something that the investigation and the public already knew, so this was not "cynical", "callous" or "sly", this was simply a release of the information gathered from the new evidence available. I'm sure that if an obvious technical or mechanical failure presented itself then they would have mentioned that.

Are you saying the thread disappeared due my posts? That would be odd, since ordinarily it is the poster who garners the ban, not the discussion, and you may have an issue not with me, but with the mods.

Not at all, but let's be honest here, you've consistently popped up every few pages to reiterate your pet opinions or theories, thus leading to the "hamster wheel" effect that the mods described. I'm not entirely innocent of that either, but I'm pretty sure I've only ever repeated myself in response to questions or suppositions put forward that had already been asked and answered multiple times.

[jcjeant]

Lyman, you may be in need of a "chill pill" again. Not only was there nothing in the "note" released prior to the 3rd interim report I'm in disagreement with the release of this note
The BEA mission is not to make some "dummy interim report" in a note to the public (and press)
It's not the rule ...
They have not to answer to press articles (they answer the press in meetings)
If they are in disagreement with the press (lies .. defamation .. etc ..) the court of justice is available and is the place for such dispute
The release date of this note .. is at least suspicious .. and it's easy to link the dots
This note was a error of the BEA .. and this added nothing to their credit of transparency or independence

[Machinbird]

Originally Posted by Clandestino
Do you have any idea what's the difference between dynamic pressure at 60 KEAS and 330 KEAS, everything else being identical?
Clandestino. This is all very irrelevant to the accuracy of the AOA vane as far as being useful. The AOA transmitters only send out an angular measurement. Nothing that is rocket science.

If the aerodynamic forces on the vane are enough to override the inherent friction in the mechanism, the vane will swing to very closely align with the relative wind. At very small AOA relative to the local air velocity vector, the inherent friction may be sufficient to create a small error provided the velocity is just above the 'come alive' speed. But in reality, once a vane comes alive, it is pretty accurate.. As I mentioned earlier, 'come alive' speed is typically in the 15-20 mph range. By the time you get to 60 knots, dynamic pressure is about 12 times higher than 'come alive' speed. More than sufficient to point the vane with extremely high accuracy. (much more than you need for basic stall warning)

The primary mode of failure that I've seen has been sticky transmitters due to contamination of the bearings and physical damage. They are really interesting gadgets. If you haven't already done so, find an opportunity to handle one.

[grity]

linktrained About sixty years ago some high performance gliders were fitted with a " Total energy Variometer" which would show the relationship between speed lost and height gained (or vice versa). These would have been non-electric ! BUT for this non electric tool you need a compensation orifice..... might also icing like pitot tube

[Lyman]

Not every pressure sensing kit needs be an orifice. I still rather like the flexible membrane, or Tympanum. For that matter, a nicely calibrated skin would suffice, were it connected to a sensing rod, and pot.

[Linktrained]

Grity,

Thank you for your comment.

In sixty years there have been improvements in battery performance in terms of capacity and weight.

A battery powered Pitot/ Static system might have been invented by now, to go with the more modern GPS fitted gliders which already in THIS century have flown higher than FL50.0. Ask elsewhere about wing deicing ! ( I am out of touch.)

[Ian W]

This may be a silly question... but the captain returned to the flight deck and apparently from the BEA transcript did not receive any briefing from the PNF or PF on what had happened and what they had tried, just questions.

So - would it be immediately apparent that the aircraft was in Alternate Law or would the captain assume that it was still in Normal Law and had a plethora of unexplained 'errors'.?

It would explain his calls to the PF to 'pull up' despite obvious indications of a stall.

[sandos]

The non-acknowledgement of Alt Law seems to me to be a major issue. Either the pilot did not understand Alt Law, or more likely in my opinion, he did not understand that it was activated. Maybe he sort of filtered away that information as "not important enough" when the PNF called it out.

[jcjeant]

Hi,

Familiares de vítimas de voo Rio-Paris querem investimento do governo para novos sensores - Internacional - R7 (http://noticias.r7.com/internacional/noticias/familiares-de-vitimas-de-voo-rio-paris-querem-investimento-do-governo-para-novos-sensores-20110913.html)

[DozyWannabe]

So - would it be immediately apparent that the aircraft was in Alternate Law or would the captain assume that it was still in Normal Law and had a plethora of unexplained 'errors'.?

One would hope that the fact that the Stall Warning was blaring as he made his way to the door and continued to do so for 2 seconds after he entered would have been a clue. In Normal Law one should never hear the stall or overspeed warning.

[rudderrudderrat]

Hi DozyWannabe,
One would hope that the fact that the Stall Warning was blaring as he made his way to the door and continued to do so for 2 seconds after he entered would have been a clue.
Do you mean - a clue that the Captain thought they were no longer stalled?
In Normal Law one should never hear the stall or overspeed warning.In Normal Law & with the AP engaged, if you are higher than ideal profile, and select Managed Descent from FL390, it's easily possible to trigger the O'Speed Warning.

[DozyWannabe]

Do you mean - a clue that the Captain thought they were no longer stalled?

I'm pretty sure you know what I was saying (the clue is in the question that I answered and quoted)...

In Normal Law & with the AP engaged, if you are higher than ideal profile, and select Managed Descent from FL390, it's easily possible to trigger the O'Speed Warning.

Fair enough, noted. However, stall warning should imply that the aircraft is not in Normal Law, can we agree on that at least? That was the question I was answering.

[CONF iture]

In Normal Law one should never hear the stall or overspeed warning.
Why not Dozy ?
Again, what are your references ?

would it be immediately apparent that the aircraft was in Alternate Law
Only a few details on the PFD or maybe the ECAM message if it was still displayed.

[rudderrudderrat]

Hi DozyWannabe,
However, stall warning should imply that the aircraft is not in Normal Law
I agree.
In the cold light of day and in an arm chair - that's an easy question to answer.

However, you believed one should never hear an overspeed warning when in Normal Law - because it says so in the manual - but it is possible.
It also says in FCOM that the stall warning will sound until the angle of attack is reduced to a safe margin - not true.
QRH 2.15 recommends 5 degs pitch with Climb Power. Since Alpha was > 45degs - that wouldn't have worked either.
Nose down activated the stall warning again (bit confusing?).
Altimeters were winding down > 10,000 ft per min - was a computer problem or a breach in the static ducts allowing cabin pressure into the static lines?
W.T.F.I.G.O?

It's taken me longer to write this than they had to recover.

[Lyman]

It seems clear that whatever the data has or will show, the a/c was handled as if oversped. Now that is an opinion, but the controls and attitudes were indicative of a mitigating plan against Overspeed.

What caused the climb, what casued the determination of the PF that they were fast, etc.?

There will always be questions unless and until BEA release all the pertinent data.

It is all well and good to pitch calumny at one direction or another, but BEA have all the cards, and they aren't talking.

How complete shall the data be to determine cause and effect? Until a likelihood is established? The climb is not unknown, it is is more like a "trait" than an anomaly. So there it is, the CLIMB. I think it very unwise to trust simplistic solutions, make a "software" improvement, and place one's cranium back in the sand.

"Work in Progress" is not something one likes to see in Aviation.......

There is a bottom line, and it has to do with how folks can deduce a chain of events from a recorder with great accuracy, yet the chain of events itself, in real time, is not privy to this exactitude, and suffers the loss. Perhaps Engineering Pathologists should sit in front.

[DozyWannabe]

Why not Dozy ?
Again, what are your references ?

Note the language - "should". References aren't necessary, it's part of the fundamental systems design. In Normal Law protections are supposed to resolve the situation before the warnings trigger. I'm aware that there are exceptions in edge cases (as rudderrudderrat helpfully reminded me).

However, you believed one should never hear an overspeed warning when in Normal Law - because it says so in the manual - but it is possible.

Fair enough.

If we start debating the merits or otherwise of the stall warning logic *again* then we'll just be going round in circles. This accident identified an edge case which will probably require a re-think of the logic - I'm not questioning that.

All I was doing was answering a question that was asked, namely, would the Captain have had any clue that they were in Alternate Law. I suggested that the stall warning should have been a clue, or at least reason enough to ask what law they were in. I'm not criticising the captain for not following that logic path precisely because the situation was so confusing for him - I'm just suggesting one possible way to work out the current flight control law based on immediate evidence.

[NARVAL]

* Two texts (the first one is very long, and is shortened here) to enlighten the subject of piloting and training for upsets.


Jacques Rosay chief test pilot « Safety First » magazine

Typically, in cruise at high Mach number and high altitude, at or
close to the maximum recommended FL, there is a small margin
between the actual cruise AoA and the AoA STALL. Hence, in
ALTERNATE or DIRECT LAW, the margin with the AoA SW is
even smaller.
The encounter of turbulence induces quick variations of the AoA.
As a consequence, when the aircraft is flying close to the maximum
recommended altitude, it is not unlikely that turbulence might
induce temporary peaks of AoA going beyond the value of the AoA
SW leading to intermittent onsets of aural SW.
Equally, in similar high FL cruise conditions, in particular at turbulence
speed, if the pilot makes significant longitudinal inputs, it is not unlikely
that it reaches the AoA SW value


The AoA decrease may be obtained indirectly by increasing the speed,
but adding thrust in order to increase the speed leads to an initial adverse
longitudinal effect, which trends to increase further the AoA
It is important to know that if such a thrust increase was applied when
the aircraft is already stalled, the longitudinal effect would bring the
aircraft further into the stall, to a situation possibly unrecoverable.
Conversely, the first effect of reducing the thrust is to reduce the
AoA

UPSET RECOVERY A Test Pilot’s point of view. (FAST N°24) by William Wainwhright Chief Test Pilot Airbus Speaking of stalls and the airline pilot’s training.
For the training managers from American Airlines, Delta, and United,
the only thing necessary was to give an overall industry approval to their
existing programmes; they already worked, because the
many pilots that had undergone training all came out of it with
the same standardised reactions to the standard upsets. For them, this was the
necessary proof that their training programme worked.
Where we differed was in our conviction that there is no such thing as a
standard upset and our reluctance to endorse simplified procedures for recovery
from an upset.
We wanted a general knowledge based approach, as opposed to a rule
based one. For this, after proposing some initial actions, we talk about “additional techniques which may be tried”. This obviously is more difficult to teach.
Even those pilots who do stalls on airtests, as might be done after a heavy
maintenance check, only do them with gentle decelerations, and they recover immediately
without penetrating very far beyond the stalling angle of attack. There
is a world of difference between being
just before, or even just at, the stall, and going aerodynamically well into it.

ON THE USE OF SIMULATORS :
We manufacturers were very concerned over the types of manoeuvres being
flown in simulators and the conclusions that were being drawn from them.
Simulators, like any computer system, are only as good as the data that goes
into them. That means the data package that is given to the simulator manufacturer.
And we test pilots do not deliberately lose control of our aircraft just to
get data for the simulator. And even when that happens, one isolated incident
does not provide much information because of the very complicated
equations that govern dynamic manoeuvres
involving non-linear aerodynamics and inertia effects.
The complete data package includes a part that is drawn from actual flight
tests, a part that uses wind tunnel data, and the rest which is
pure extrapolation.
It should be obvious that firm conclusions
about aircraft behaviour can only be drawn from the parts of the flight envelope
that are based on hard data. This in fact means being not far from the centre
of the flight envelope; the part that is used in normal service. It does not
cover the edges of the envelope. I should also add that most of the data
actually collected in flight is from quasi-static manoeuvres. Thus, dynamic
manoeuvring is not very well represented. In fact, a typical data package
has flight test data for the areas described in Table 1.
In other words, you have reasonable cover up to quite high sideslips and
quite high angles of attack (AOA), but not at the same time. Furthermore, the
matching between aircraft stalling tests and the simulator concentrates mainly
on the longitudinal axis. This means that the simulator model is able to correctly
reproduce the stalling speeds and the pitching behaviour, but fidelity is
not ensured for rolling efficiency (based on a simplified model of wind
tunnel data) or for possible asymmetric stalling of the wings. Also, the range
for one engine inoperative is much less than the range for all engines operating
and linear interpolation is assumed between low and high Mach numbers.
Wind tunnel data goes further. For example, a typical data package would
cover the areas described in table 2. In fact, this is a perfectly adequate
coverage to conduct all normal training needs. But it is insufficient to evaluate
recovery techniques from loss of control incidents. Whereas, the training
managers were all in the habit of demonstrating the handling characteristics
beyond the stall; often telling their trainees that the rudder is far
more effective than aileron and induces less drag and has no
vices! In short, they were developing handling techniques from
simulators that were outside their guaranteed domain.
Simulators can be used for upset training, but the training should be confined
to the normal flight envelope. For example, training should stop at the
stall warning. They are “ virtual” aircraft and they should not be used to develop
techniques at the edges of the flight envelope. This is work for test pilots
and flight test engineers using their knowledge gained from flight testing
the “ real” aircraft.


Vereinigung cockpit, the German syndicate has issued a press release that says that blaming the pilots and only them is far too easy. (On their internet site, press releases)

[roulishollandais]

They are many confusion about different loss of control :
Stall and spin, deepstall, lazy eight, dutch roll, rupture of rudder, are all specific and very different.
Equations are very different. Litterature is not very adapted to describe these different behaviours of the plane.
I know some things about dutch roll, but less about deepstall. Perhaps could a test pilot explain some more about specificity of deepstall which has PERHAPS been the case in AF447.

[CONF iture]

References aren't necessary, it's part of the fundamental systems design. In Normal Law protections are supposed to resolve the situation before the warnings trigger.
To the contrary, in Normal Law overspeed protection will resolve the situation only once the warning has been triggered.

No other choice than to be challenged for references as you keep making statements that are in no way part of the fundamental systems design.

[NARVAL]

Roulishollandais: specificity of deepstall which has PERHAPS been the case in AF447.
Saying that shows that you are honest and open-minded.
In fact I believe it was a perfect example of deep stall. Stable, with only roll excursions. The angle of attack at a very high value, and a stable (awful) rate of descent. To "break" this stable descent, you need flight control efficiency to decrease the angle of attack (with a full "up" THS (or PHR fot the french) was the elevator sufficiently powerful?) and you need to use engine's secondary action (reducing completely will help to decrease the angle of attock)...
But every plane has its idiosyncrasies, and this had never been tried on the A330. I remember, long ago, in Bretigny (flight test center at the time) a French Navy Crusader being tested after two losses following unrecoverable spins. The test pilot used full reheat (post-combustion) to manage decreasing the angle of attack and getting out of the spin. I worked a lot with him later on, and of course, if he had been in the A330...But such pilots are scarce in the airlines nowadays.

[Zorin_75]

It also says in FCOM that the stall warning will sound until the angle of attack is reduced to a safe margin - not true.
I think nobody will disagree that the deactivating stall warning is not a bright idea. It should be noted though that it took a lot of effort to get the a/c that far over the edge.
QRH 2.15 recommends 5 degs pitch with Climb Power. Since Alpha was > 45degs - that wouldn't have worked either.5 deg /CLB is a worst case interpretation (I'm sure most are aware of this Flight Safety Article? Aviation Troubleshooting: AF447 - Unreliable Speed - by Joelle Barthe, Airbus Engineer (http://tinyurl.com/3or72nd) ) of the UAS procedure. Had it been applied we wouldn't be having this discussion.

[Superpilot]

This neat piece of technology has the potential to avoid another AF 447.

Garmin Aera 795 Touchscreen GPS (http://www.transair.co.uk/sp+Garmin-Aera-795-Touchscreen-GPS+2795)

Of course, it's based on GPS signal and needs to be understood differently to traditional instruments but a few simple rules of thumb allow you to fly any aircraft both accurately* and safely* using this.


*when you have nothing else to help you achieve accuracy and safety.

[DozyWannabe]

To the contrary, in Normal Law overspeed protection will resolve the situation only once the warning has been triggered.

OK, fair enough and noted (as I said to rudderrudderrat). The protection/warning coupling we're talking about in this case is stall, not overspeed. Several people other than myself have stated that you should not hear the stall warning when in Normal Law.

No other choice than to be challenged for references as you keep making statements that are in no way part of the fundamental systems design.

Given that you've insisted for years that the yoke is an inherently safer system with no evidence to back it up, I guess that makes us even.

[Lyman]

Three seconds before loss of Autopilot, the aircraft is climbing at 1000 fpm with her NOSE DOWN four degrees off cruise. five seconds later, the NOSE is passing through 0 degrees and rising.

1000fpm UP and NOSE DOWN is a/p logic for UPDRAFT. If the UPDRAFT disappears, the NOSE will start to rise to lose the indicated and (actual) speed increase. These airspeed anomalies are more than sufficient to waste the ADR's in the eyes of the FC.......

The STALL WARN has a demonstrable failure mode, that we didn't know about.

You are a fair man, and very fluent in systems, DOZE. Do you care to address this possibility of OVERSPEED sans WARN?

The only conclusion I cannot accept as exculpatory is lack of WARN.

Further, these reads and prompts would not be accurate, but sufficient to cause degrade, PF takeover, etc.

It also explains perfectly the ensuing climb, since "crazy speed" cannot be dismissed, especially as an indicated speed.



Sir?

[CONF iture]

Several people other than myself have stated that you should not hear the stall warning when in Normal Law.
But you still can.
One reason is mentioned by Jacques Rosay here (http://www.pprune.org/6699365-post885.html).
Another is the case of a damaged AoA that could trigger a continuous stall warning.

Given that you've insisted for years that the yoke is an inherently safer system with no evidence to back it up, I guess that makes us even.
Not too much my style to state that that x is safer than y but please quote me … ?

On the other hand, my position has always been clear :
Sidesticks a la sauce Airbus, is a sure path to waste very valuable information in a multi-crew operation.

The BEA has simply not the latitude to acknowledge such evidence.
Never they would ever mention for the final on 447 that 2 Pilots Monitoring had not the best tool to positively be aware of PF’s inputs.
IMO it is a bare minimum for the Findings.
Beer is on me if they do …

[Clandestino]

Machinbird, given quality of discussion on this thread, it seems that my attempt at trying to open meaningful discussion on how it's difficult to design, manufacture and install the AoA probe that would work accurately and reliably all throughout the modern jetliner envelope has complettely flopped. Against the arguments "I have moved it by hand easily so it must work below 60kt", "It's not rocket science", "pressure affects both of its sides" and "find an opportunity to handle one" I'm totally powerless. Quite amused, too. Still, I maintain that indignant request for AoA vane to work flawlessly far outside the flight envelope is so unrealistic as to be ludicrous. I can take some comfort form making a big, fat assumption that it stems from ignorance and not agenda.

Anyway, workings of Airbus AoA wane and stall warning system are relevant only in the context of theory that claims the crew which has ignored the stall warning for 54 seconds and after that canceled it's push and pulled when warning sounded again - twice, therefore showing complete inability to comprehend what was the meaning of warning or what is happening to the aeroplane, would miraculously snap out of its confused daze and suddenly react properly only if the warning didn't stop when the aeroplane was where no test pilot dared to take it before. Quite a stretch, isn't it?

Sidesticks a la sauce Airbus, is a sure path to waste very valuable information in a multi-crew operation.

The BEA has simply not the latitude to acknowledge such evidence.Aviation accident investigation entities have obligation to reliably collect facts and analyze them as accurately as possible. Admitting someones baseless pet theories as evidence is not helpful to their aim is therefore not practiced. Moanings on anonymous forums can not be considered to be reliable evidence. Besides, delusion of vocal minority that they're representing the silent majority is as at least as old as written history itself.

[ChristiaanJ]

Machinbird, given quality of discussion on this thread, it seems that my attempt at trying to open meaningful discussion on how it's difficult to design, manufacture and install the AoA probe that would work accurately and reliably all throughout the modern jetliner envelope has complettely flopped. Against the arguments "I have moved it by hand easily so it must work below 60kt", "It's not rocket science", "pressure affects both of its sides" and "find an opportunity to handle one" I'm totally powerless. Quite amused, too. Still, I maintain that indignant request for AoA vane to work flawlessly far outside the flight envelope is so unrealistic as to be ludicrous. I can take some comfort form making a big, fat assumption that it stems from ignorance and not agenda.I'm still baffled.... why 'blame' the AoA vane?
The often-quoted recorded 60kts IAS was a result of the UAS (blocked pitots), it was NOT the real IAS of the aircraft at the time in question.
A lot of posts here do not seem to have made that easy conclusion....

[roulishollandais]

@ NARVAL

Thank You.

Not only the Crusader has deepstall : the Learjet of MICHEL BAROIN, father of FRANCOIS BAROIN, crashed in a dutch roll, followed by a deep stall... (february 5. 1987). Can the BEA remember that precedent fact ?
Only very very few people, and none in Congo from 1987, could imagine that the pilots would not be able to come out from the dutch roll and try to transform a murder in an accident, and how to organize that (As Dominique Lorentz wrote it in a book (1997 "Une guerre").

Surely the end of the AF447 diving under 45° in the ocean, looks like a deepstall. But "stable" is not the good word when we look BEA's report 3, annexe 4 :
Around 02h10m07s we can see the begining of a lateral autooscillation (page 115), and later around 02h11m40s we can see the begining of a longitudinal autooscillation (page 114). Oscillation does not go with "stability" in the automatician language.

It is strange too that the yaw damper began to oscillate at 02h09m35s, but very slightly. And the loos of IAS happened just after 2s delay in engine deicing : I don't affirm, but it would be well to study the case. Indeed a dutch roll can start on any aircraft when ice comes or goes away from the aircraft.

Another problem is the ability of any stall warning to prevent the deep stall : it is not the wing, but the whole aircraft who has a bad incidence.

[Clandestino]

I'm still baffled.... why 'blame' the AoA vane?Because what was discussed is the part following the actual aerodynamic stall, where the ice has melted away, indicated airspeed was realistically measured to be below 60 kt and AoA exceeded 45°. Someone with not much knowledge about basic aerodynamics or flying dug out the certification requirement that stall warning should sound as long as the aeroplane is stalled, took umbrage at Airbus' decision to use 60kt instead of WoW to invalidate AoA measurements, thereby cutting off the stall warning and here we are. One step short of insisting that X-31 style probe should be installed on all airliners.

[rudderrudderrat]

Hi Clandestino,

Please explain how a ROD of 10,000 per min (about 98 kts) is not sufficient to validate the stall warning.
The invalid <60 kt logic must was meant for on ground nuisance warnings.
Using the same logic when airborne must have been designed by Someone with not much knowledge about basic aerodynamics or flying

[xcitation]

The often-quoted recorded 60kts IAS was a result of the UAS (blocked pitots), it was NOT the real IAS of the aircraft at the time in question.
A lot of posts here do not seem to have made that easy conclusion....

Coupling the stall warning to the IAS is clearly a problem. This cross dependency needs to be eliminated. If you lose/degrade IAS <60kts then you lose the stall warning! But when you lose IAS you need a stall warning more than ever. The only work around is to select the AoA display.

[ChristiaanJ]

Coupling the stall warning to the IAS is clearly a problem.We've been there before... and unfortunately we have no comment from whoever designed that logic, instead of just using WoW.
Somehow IAS <60kts at altitude was never considered....

Oddly enough, I still remember an [IAS <60kts] switch in the logic of a FCS I was involved in.... but it was an analogue system.... and it was a helicopter.... so not relevant here.

[Machinbird]

Clandestino
Against the arguments "I have moved it by hand easily so it must work below 60kt"You must have missed the post where I stated I had personally tested an actual airline (In this case DC-9) AOA transmitter and that it came alive at 15-20 mph based on my vehicle's speedometer reading. Since I drove in a closed course and had consistent results, wind was a negligible factor.

I suppose it is possible that the A330 AOA transmitters require much higher dynamic pressure to provide accurate readings, but somehow I doubt that the manufacturers were that inept.

The term 'come alive' means that the transmitter has enough aerodynamic force operating on the vane to cause the vane to point in the direction of airflow and to maintain its direction while you turn the body of the transmitter. The difference between 20 mph and 60 knots is a factor of 12 increase in dynamic pressure.

my attempt at trying to open meaningful discussion on how it's difficult to design, manufacture and install the AoA probe that would work accurately and reliably all throughout the modern jetliner envelope has complettely flopped. The design and manufacture of electrical AOA transmitters has been going on for well over 50 years. A Korean war vintage jet I used to fly had one.

The design and manufacture are not trivial, but it is an art that is well understood.
The location of the AOA transmitters on an aircraft, requires understanding of the flow fields around the aircraft at various angles of attack and selection of one which will create the most representative indications.

The modern jetliner envelope is nothing unusual, you guys usually like to stay sub-sonic.:}

I do not know why Airbus allowed the AOA indications to be invalidated by speeds <60 knots, but "there is more than one way to skin a cat," and more than one way to achieve whatever objective they were attempting to achieve with that logic.

As I have stated numerous times, AOA is primary flight information and airspeed is primary flight information and they are each independent variables. To permit one to disable the other is setting up a loss of both pieces of information. Conceptually, this is poor logic from a reliability standpoint. It is just that the 60 knot point is so far out of the normal flight envelope, that the engineers never dreamed that it could potentially be a problem for someone.:sad:

We do not need X-31 style probes for airliners. The existing ones work well enough. Once AOA is well away from normal flight envelope, that is good enough information to work with unless you are running a full stall characteristics flight test.

But you do need to know that AOA is approaching flight envelope limits, preferably with a stall warning device that cannot be ignored and an actual indication to reinforce that information.

[CONF iture]

Aviation accident investigation entities have obligation to reliably collect facts and analyze them as accurately as possible.
Of course ... Nevertheless they do not share all the facts starting with data and won’t necessarily feel the need to share all of their analysis, with Clandestino or CONF iture.

[gums]

I gotta go with 'bird and other pilots.

I realize that an airspeed below 60 knots ( TAS, EAS, IAS, CAS, whatever) is unlikely once airborne. OTOH, the AoA vanes or conical probes or whatever are independent of the pitot-static system.

If the pitot-static sensors go tango uniform, then do we ignore the AoA sensors?

Somehow, I get the feeling that the cosmic engineers never expected the jet to have unreliable dynamic pressure and then get close to a stall. Just ignore the AoA sensors, huh? This is despite the fact that actual EAS/CAS in the AF jet was above 60 knots and the AoA sensors were prolly still providing valuable data to the FCS.

Sounds like a fault tree analysis is in order.

I flew two jets before the Viper with the old-fashioned vane style AoA doofers. Then I flew the Viper that had the conical AoA things with slots in them. The Viper also had a pneumatic, hemispheric probe that provided another AoA indication and sideslip inputs for the FCS. If we lost dynamic pressure we used "standby gains" for "q", but still used the AoA data. Worked for me and thousands of Viper pilots.

If the AoA sensors are getting weird due to actual aircraft flight conditions, then no big deal. It means that the jet is doing something weird!! So don't ignore the sensor values.

And then there's all the "alpha prot" and other "laws"/"sub-laws" and on and on and on. Sheesh. Too many autopilot functions are embedded in the design. Maybe have reversion "laws" that are clearly defined and get rid of all those functions that should be allocated to Otto when it is engaged. And make no mistake, I am not advocating a reversion to "direct" law. There needs to be a basic "law" that uses basic flight dynamic data to provide the pilot a "basic" airplane to fly. If you lose dynamic pressure, then use AoA. If both go tango uniform, then pitch and power are the drill.

[CONF iture]

I am not advocating a reversion to "direct" law. There needs to be a basic "law" that uses basic flight dynamic data to provide the pilot a "basic" airplane to fly.
That what is Direct Law gums.

[grity]

gums If you lose dynamic pressure, then use AoA. If both go tango uniform, then pitch and power are the drill.is´n it the same for the AP? is it realy realy that an airbus in his auto-logic hold the altitude with the elevator+trims and hold the speed with the power ??? should the AP not hold the altitude with the power and the AoA with the elevators ? at least in case without dynamic pressure.....

[Linktrained]

NARVAL #885

Thank you for guiding me (and others) to Jacques Roysay's article in "Airbus Safety Magazine" of January 2011.

IIUC, he suggests that, in Direct or Alternate Law, one should fly 4000 ft. below the height recommended for FBW, especially in turbulence. (To keep the SW quiet ?)

He also discusses SW and the use of TOGA on flights at lower levels (in a 340)

[Ian W]

Clandestino
"Anyway, workings of Airbus AoA wane and stall warning system are relevant only in the context of theory that claims the crew which has ignored the stall warning for 54 seconds and after that canceled it's push and pulled when warning sounded again - twice, therefore showing complete inability to comprehend what was the meaning of warning or what is happening to the aeroplane, would miraculously snap out of its confused daze and suddenly react properly only if the warning didn't stop when the aeroplane was where no test pilot dared to take it before. Quite a stretch, isn't it? "

Clandestino it is not a stretch at all - and I am sure I could make you react in a similar way in a simulator where you 'totally fail to notice' something that is obvious to an outside observer. Overload a cognitive channel and NOTHING else will be processed by it. There is a famous experiment where a team of observers of a basket ball match did not notice a man in a gorilla suit on the basket ball court. Or for an aviation example a set of fighter pilots flying a 'highway in the sky' type display who on overshoot each flew through a blimp that was VERY obvious in front of their simulated aircraft. Then there was the YouTUbe video earlier in this thread showing a crew of three landing an aircraft wheels up while in the background for the entire approach the undercarriage warning horn was sounding. The examples are endless.

Unfortunately, people who disbelieve the existence of cognitive overload have been allowed to design, test and implement aircraft systems. Setting up the potential for just the type of human factors caused accident that we have seen in AF447.

This is why there is now a human factors team analyzing what happened. It would have been far better for the passengers of AF447 if the human factors analysis of what could happen had been before release to service

[Lyman]

Likely the release of the CVR record will explain the PNF's "What was that?"

Frankly, BEA have no choice, since they have ascribed his comment as "Probably related to the STALL SV."

Without actually hearing the noises in the cockpit, they will be stuck with "Probably". So that much more data will be forthcoming, what a relief.

Right, CONFiture?

[IFLY_INDIGO]

This accident shows that how much we rely upon the indications inside that we forget to look outside and fly using stick and rudder :uhoh:

[GerardC]

1) Does anyone know why AP disconnected at 02:10:05 ?

According to NTSB (and AI), see : DCA09IA064 (http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20090706X72654&key=1) : "According to Airbus documentation and analysis, if an airspeed discrepancy of more than 20kts or an altitude discrepancy of more than 400ft is detected between one ADR and the two others, the subject ADR is rejected. Then if a discrepancy occurs between the two remaining ADR, all auto flight functions are lost and autopilot, flight director, and autothrust disconnect.".

I do not see any discrepancy between the two recorded AS before, at least, 02:10:07.5.

In the TAM case : "the No.1 ADR airspeed dropped rapidly from about 260 knots to approximately 60 knots for a few seconds, then rose to 100 knots. At the same time, the recorded pressure altitude dropped by about 300 feet. About one minute later, the autothrust and autopilot disengaged..."

Why such a hasty AP disconnection in the AF 447 case ?

2) Why did the "NAV ADR DISAGREE... IF SPD DISAGREE... ADR CHECK PROC... APPLY " ECAM message came in as late as 02:12:XX ?

[Lyman]

GerardC

There is an additional circumstance. Without discrepancy among the ADRs, but with a drop or gain of >30 knots with the concurrence of all three, the automatics drop out. This is sudden, and would seem to relate to the need for immediate manual control, as in WIND SHEAR.

Turbulence is the prime candidate for even a conformal change in airmass speed (or direction, sensed as the 'same thing' by the a/c).

The sudden loss of a/p is consistent with the lack of a 'run of the mill' UAS.

It also argues against ICE having any impact on the Probes. Beyond this, airspeed variance of this order would also be associated with OVERSPEED PROTECTION.

Overspeed (a/c reaction to) explains the fixed position of the THS in the climb.

Similarly, a possibility of this sort explains why the speeds did not become discrepant until after the loss of a/p, and the degradation to AL2.

My understanding is that with WIND SHEAR, the a/c remains in NORMAL LAW. This also would explain why, if so, the PF was convinced he was in NL well into his climb, and felt safe in Pulling aft stick.

[DozyWannabe]

Unfortunately, people who disbelieve the existence of cognitive overload have been allowed to design, test and implement aircraft systems. Setting up the potential for just the type of human factors caused accident that we have seen in AF447.

That is a complete falsehood. Half the reason for the somewhat arcane annunciation logic employed in modern airliners is for the precise reason that cognitive overload is so feared and to be avoided. This is why Stall Warning quite literally trumps a whole host of others.

@Lyman - give it up. The aircraft did *not* climb due to autoflight input and autoflight did not move the THS. It was pilot input, pure and simple. The reason for the delay in disconnect and the message is purely because it takes some seconds for an initial ADR discrepancy to become a confirmed ADR DISAGREE status, as was mentioned quite clarly in the earlier threads.

[Lyman]

Dozy. Nothing of any conclusive value has been demonstrated, other than to the threshold of this forum (!).

Autoflight did indeed initiate a NOSE UP at hand off (with the AoA at three degrees below cruise), and was climbing the a/c at 1000fpm (conservative) by the traces published by the BEA. This is in the record, and autoflight would not have climbed the a/c after that, where did I post that?

Neither did I posit a delay in "disconnect", where do you get these things? Of course the PF did not change the THS in the climb, it did not move at all. This is not consistent with anything other than a potential for Overspeed protection. You have eliminated that? You are making wild statements where BEA is still using "Probable", etc. Who is the rabid one here?

[DozyWannabe]

The point is that it appears that you're arguing that the autoflight should be considered in part responsible for the zoom climb initiated by the PF (as I read it), which doesn't look to be the case. You're also arguing overspeed protection coming into play, despite the fact that even CONF iture himself has said that in Normal Law, the Overspeed warning will sound before any protections kick in. There were no occurrences of overspeed warning on either the ACARS or the CVR, based on the material released so far. You've been continually trying to argue that the aircraft was responsible for the loss of control and you say you're doing this to "defend" the pilots. Defend them from what?

In the legal sense, it's always going to be a case of split responsibility between Airbus and the airline because of the known pitot tube issues and the subsequent mishandling of the aircraft.

[Lyman]

Autoflight is not responsible directly, no, though the a/c was given to PF with a need for correction eg climb, roll.

The CVR showed no warning for the simple fact that it has not been released, only a very few transcribed statements. The ACARS is not the Gold Standard, as you would believe, it simply is not.

You insist on eliminating possibilities out of bias, or worse, even pique. I am not aware of evidence eliminating the possibilities about which I inquire. If you have it, and will show it, let's move along, indeed.

BEA had their Pirate's opportunity to exonerate the airframer, which of course is not the case, in fact, or in evidence. They proclaim no new issues.

Why? Because they have not been announced? Have you taken a page from their book?

I submit that the beliefs of those who wish the a/c to be found innocent are spitting into the wind.

Until sufficient evidence exists from its source, let's just discuss?

I will repeat, you waste time in rejecting my opinions out of hand.

No evidence of computer aided PITCH UP? Not exactly a sound defense, at this stage.

I asked an honest question earlier, with a possibility that has not been addressed in detail....You overlooked it?

[DozyWannabe]

BEA had their Pirate's opportunity to exonerate the airframer, which of course is not the case, in fact, or in evidence. They proclaim no new issues.

You use phrases like that and accuse *me* of bias?

You also mentioned "joining the dots" earlier, implying an effort to "exonerate" Airbus (even though, as I have said before they will have to carry at least some of the responsibility for the pitot problems), yet you provide no proof.

If there was an overspeed warning then the BEA would have mentioned it - there is absolutely no reason for them not to.

Sometimes a windmill is just a windmill.

[Lyman]

For crying out loud, of course you are biased. At least I admit to it.


Va Bien Quixote......

bon chance

[DozyWannabe]

If, by "biased", you mean "not inclined to immediately suspect any French institution of skulduggery", then I'm guilty as charged - otherwise I'd say I'm fairly neutral. All I ask is evidence of the supposed dots you are joining.

How else am I supposed to understand what you're getting at?

There is no reason - none - for the BEA to fudge anything here even if they wanted to (the A330 is already a successful airliner, and all the evidence so far suggests that they are throwing everything they can at the investigative process). I ask again, what is it that you think you're "defending" here?

[jcjeant]

Hi,

In the legal sense, it's always going to be a case of split responsibility between Airbus and the airline because of the known pitot tube issues and the subsequent mishandling of the aircraft. I will repeat (I posted already about)
On a pure legal sense .. AF is not a culprit concerning the Pitot tubes
It was not a law to force AF to change or replace the Pitot tubes.. it was only recommendations
You can't break a law if this law don't exist !
AF bear not responsibility concerning the Pitot tubes .. in the legal sense

[DozyWannabe]

jcj:

The point I'm trying to make is that the pitot tube issues mean that Airbus is going to have to share responsibility in some way, I wasn't saying that AF should hold all responsibility for that. The way Lyman puts it, you'd think Airbus was going to be completely absolved - all I was saying is that they can't be.

[GarageYears]

So I went away for a week of real work and return, only to find this thread appears to have rewound several weeks to repeat a topic already hung, drawn and quartered - or at least it seemed so.

Here's where I thought we were:

a) All the adults seemed to agree that the 'zoom-climb' was induced by PF action. The stick-trace shows PF NU inputs, that correspond with control surface movements, that correspond with altitude change...

b) The NU inputs were not continuous (at this point) and hence not sufficient to demand a trim input from the THS. However later in the event, PF did pull, long and hard NU, such that the THS moved, as demanded, to off-load what the pilot appeared to desire.

c) That the "auto-flight", protections or any other computer induced skulduggery had anything much to do with what went wrong seems to be absent from all the evidence so far, excepting that at autopilot release the aircraft needed a mild roll correction.

d) We have seen that certain contributors here have an amazing ability to add 2+2 and get -47, in other words theories with little basis in fact, but equally little to dispute them, which in the mind of the author therefore gives them legitimacy... much to the frustration of many others. Just because something is possible does not mean it is likely. The shortest route between two points is the straight-line. While it is true we do not have all the 'dots', those that we do have, are pretty convincing.

Anyway, I'm not sure I'm contributing much here, except to get my mind straight, so I'll shut-up for a bit longer.

[3holelover]

Contributing something?!? Are you kidding!? That's an excellent summary Garage Years! Concise, and spot on, by my read....

[Lonewolf_50]

IFLY_INDIGO
This accident shows that how much we rely upon the indications inside that we forget to look outside and fly using stick and rudder
Right.

Night, IFR, lots of clouds, near large buildups, fly by looking outside the window for your visual reference.

For whom do you fly, sir? :confused:

[Lyman]

GY

Are you at all interested in what PNF meant: "What was that?" How about PF: "I think we have some crazy speed".....

You are satisfied with the presumption that the THS stayed where it was due lack of loiter at NU with the Stick?

As a sound professional whose goal is to challenge and improve the industry, you seem easily satisfied.

In a difficult investigation into a vehicular homicide locally, the defense team was frustrated by lack of witness production by the Prosecution at Trial.

Our firm found a witness who had been interviewed, and the report taken and memorialized by the State Police. It was not produced at discovery, and the upshot was that it had been hidden from the accused's counsel.

The case was dropped, with prejudice.

I am no longer trusting of the folks who are charged with Public Duty.
Certainly not when they own a financial stake in the airframe manufacturer. BEA does just that, they share a stake in the future well being of a firm that thus far has been shown to be negligent in some areas related to AF447.

Are you ffs kidding me? 2+2=47?

[DozyWannabe]

I am no longer trusting of the folks who are charged with Public Duty.
Certainly not when they own a financial stake in the airframe manufacturer. BEA does just that, they share a stake in the future well being of a firm that thus far has been shown to be negligent in some areas related to AF447?

How do you work that out? How does the BEA, an independent government department, "share a stake" in a publicly-held international corporation that manufactures airliners?

By your logic, we should also be suspicious of the NTSB's neutrality towards Boeing (which, although nominally publicly-held, relies on government contracts to shore up the lean times in the civil market).

So please, provide some direct evidence that the BEA has any stake in the outcome of the investigation, or leave the subject alone.

[ChristiaanJ]

Dozy,
Please stop feeding the troll.....
I would like to put him on my 'ignore' list, but since he changes his ID continuously, and then pollutes the thread yet again, that isn't practical, if one tries to follow the posts.

[Lyman]

Dozy. NTSB? Suspicious? You must live in dreamland, or have nil experience in PUBLIC/PRIVATE partnering. The government of FRANCE owns a 15 per cent financial stake in Airbus, and BEA is an arm of the executive duty of the government.

You make assumptions that are amusing, as does Mr. Concorde.

Two weeks ago, a popular politician was found to have been behind a loan guarantee to a private Company. The Company has since gone Bankrupt, and has lost hundreds of millions of PUBLIC MONEY.

You are naive beyond belief, and trusting in areas patently populated with menace, greed, and public gullibility.

NTSB? Like the time when presented with new evidence in an ongoing investigation rejected it, because the leader was to start his vacation?

You are as a child.

[structor]

I think the advice to ignore Lyman (in his/their current manifestation) is wise. If Lyman is not a Troll but an Aviation Professional it is very strange that "he" chooses to communicate in a way that does not reflect the economic and efficient use of language essential to, and respected by, the Aviation Community.

If "he" truly believes in the ideas that "he" seems to be trying to get accross to others then why does he not understand about signal-to-noise ratio?

[HarryMann]

I have to say, after many months with Bearfoil and Lyman posts, however open-minded I do try to be, finding it all very enervating :(

[Mr Optimistic]

To my mind the disquieting thing here is how the design of a machine and the attendant training culture appears to have put a cognitive boundary between the crew and physical reality. It seems that three intelligent and well trained men sat dumbfounded and incomprehending unable to discern which signals were real and which were artefacts.

[VGCM66]

Lyman wrote:
Our firm found a witness who had been interviewed, and the report taken and memorialized by the State Police. It was not produced at discovery, and the upshot was that it had been hidden from the accused's counsel.

If you are an ambulance chaser related, you can't never accept a pilot's error verdict. There is no money to be made. Wasn't it you or early incarnation against the NTSB final report of the American Airlines Flight 587? :=

Just wondering aloud.

[GarageYears]

Lyman... exasperated!

Are you at all interested in what PNF meant: "What was that?" How about PF: "I think we have some crazy speed".....

You are satisfied with the presumption that the THS stayed where it was due lack of loiter at NU with the Stick?

As a sound professional whose goal is to challenge and improve the industry, you seem easily satisfied.Hi Lyman, well I thought we had said our goodbyes, but here you are....

As a sound professional I am constrained by the limits of the data presented to me. I cannot analyze what I do not have recorded, I cannot simulate that which I cannot hear, etc. In other words, beyond a certain point I am making sh*t up. I try to avoid that.

I appreciate the comments you mention might be sound related, but don't I have enough information to definitively state what is or isn't going on? I think not. Can I hazard a guess?

Perhaps...

PNF: "What was that?" --- no, here I can't. Having heard the stall warning from the FWC, it is hard to imagine this being misunderstood, if that is your implication. The Cricket_Stall warning is a unique dual-tone that is interrupted by the spoken word "Stall" repeated every second, so you get something like, "de-da-de-da-STALL-de-da-de-da-STALL...etc". It's alarming and clear. Anyone that ignored that is pretty focused! Did the PNF hear something else? See something else?


PNF: "I think we have some crazy speed" --- yes, my guess is something like this > Once in the stall, the vertical speed would have introduced an unusual and unfamiliar wind-rush sound. Given the AoA, this sound would have had an unusual direction and I suspect character. Perhaps this was mistaken for overspeed. A stall-induced, vertical speed sound is NOT simulated in any flight simulator I have ever been inside.

As for where the THS stayed. Surely we have discussed the behavior? You hold NU for long enough and the THS trims NU, hold ND for long enough and THS trims down. What else do you need to be told?

[Zorin_75]

PNF: "What was that?" --- no, here I can't. Having heard the stall warning from the FWC, it is hard to imagine this being misunderstood, if that is your implication. The Cricket_Stall warning is a unique dual-tone that is interrupted by the spoken word "Stall" repeated every second, so you get something like, "de-da-de-da-STALL-de-da-de-da-STALL...etc". It's alarming and clear. Anyone that ignored that is pretty focused! Did the PNF hear something else? See something else?

Somewhere earlier in this or the other thread some of our french friends had explained this to be an expression more or less equivalent to "what the *beep*?"
He's surprised to get a stall warning, but he knows exactly what he's hearing.
I concur that not paying attention to certain posts is probably the only way to prevent this hamster wheel from turning until any sane person participating will be exhausted.

[Lyman]

Yes, sound. Of course PNF recognized the STALL click click click STALL...etc. I think in this case, the sound attenuated prior to the cricket clicks. A "Nibble" then.

'Crazy Speed'. I had an open aux window in a 402 at 200+ knots, the sound was impressive. When it slammed shut, it broke, and it was hard to concentrate on the flying.

I think PNF was unimpressed with PF's PITCH control, and I am suspicious that it was due to other than his ordinarily (assumed) quality of manual flight.

So many things do not add up, here. It is easy to allow a prejudice to explain it away....."stirring Mayonnaise". "Twitchy ailerons" "Ham handed" etc. ad nauseum.

I will always assume everything was working as expected, until the proof is shown me. The released data is highly prejudicial, and I am used to it, I write it, and I defend it, and I attack it. It is "Jargon". Those unaware of the domain are excused their naive acceptance of "as written".

The PITCH, dependent "as it was" on PF's "Constant back stick" shows no follow on by the THS, and you cannot explain it. No one has. One second is all it takes for the slab to articulate and trim out the elevator. One cannot stir mayonnaise and have the THS refuse to move, the Bus is not built that way. Neither is the sharp AoA change due only PF's hand. I say that without evidence, how can that be? A frozen THS and an additive elevator input to PF's explains the unknowns perfectly, and these have not been eliminated. Unless and until I see (or hear) conclusive evidence, there is no conclusion.

BEA have concluded "nothing". Funny that? I wish for an open minded discussion, not slander and schoolyard name calling from purported 'heroes' of aviation. But I won't hold my breath.

I appreciate your comments; they are valuable as your name calling is useless.

The THS appears not to have moved from a/p loss to STALL, up or down. One circumstance explains that, and I have seen no evidence favoring or negating that very thing.

Unless........We will find out, won't we?

signal: The THS did not move from -3 degrees until the STALL. Consistent with Overspeed Protection.

signal: Pilots were alarmed at rate of climb. Consistent with automatic increase to Pilot's inputs of UP elevator in Overspeed Protection.

[DozyWannabe]

No Lyman - the THS does not move much prior to the stall because there is no reason for it to move. The THS is a surface that is designed to compensate for long-term changes in attitude. It therefore follows that in order to move it a significant amount, the demand has to be made and held for a significant period of time.

Reading the traces, it does just that, when the PF goes from "making mayonnaise" with the sidestick (where it moved slightly following a general nose-up trend in the inputs made) to holding the thing back against the stops for the best part of a minute.

The computer did not order an overspeed protection sequence because there was no overspeed situation detected by the sensors and instruments. Are you seriously accusing the BEA of wilfully deleting an overspeed warning trace from the CVR? If so I'd have to see some pretty significant evidence before I'd be inclined to take you seriously. Your suppositions have now crossed the line into unadulterated fantasy.

I've decided to do as I've been asked and henceforth leave you alone. If that means this thread becomes an endless circle-jerk between yourself and the Michel Asseline fan club making up ever more lurid theories about how it must have been the computers at fault, I no longer care.

[Lyman]

Dozy

Not only did the THS not move much, it did not move at all. I consider a climb of three thousand feet a "long term change in attitude". I do not accuse BEA of deletion at all; if O/P exists, it is unreported. Until the CVR is released, you need to stop making assumptions first of all that I accuse anyone of wrongdoing, and secondly, that you understand exactly what transpired.

You are quite right in another regard, my attempts to keep the collective mind ajar are futile, and have cost me dearly in the good will of ones I had befriended, and befriended me. For this I am sad......

I will not soon understand why posters here consider themselves better judges of content than the owners of the website. My questions are unanswered except by a sniff and an opinion, I see no proofs offered.

I have not demeaned or attacked, I have asked only questions that have yet to be answered by proofs. If you are offended by my crack about being naif, then so be it. You are trusting to a fault. I have long accepted that the pilots effed up, you seem unwilling to allow others to question the airframe at all.

[infrequentflyer789]

GY

Are you at all interested in what PNF meant: "What was that?" How about PF: "I think we have some crazy speed".....


I am more (or at least equally) interested in "je suis en toga, hein ?" and "On a pourtant les moteurs qu’est-ce qui se passe (…) ?"

"crazy speed" - crazy high or crazy low ? They never acknowledge stall, [I]unless the toga comment is reference to that, so maybe they thought they were overspeed - but they engaged toga, to respond to overspeed. Really ???


You are satisfied with the presumption that the THS stayed where it was due lack of loiter at NU with the Stick?
I am satsified that from basic aerodynamics, the control surface movement required to achieve the same climb demand at high airspeed (initial climb) will be less than that required at low airspeed (later), and hence the likelihood that THS will need to move to unload it will also differ. Further, I am sure that the sims have data to replicate that. Finally, I'm sure BEA haven't faked the sim data lining up with the real data - too easy to get found out, and why not just fake the FDR data at issue if you are going to fake stuff...


I am no longer trusting of the folks who are charged with Public Duty.
Those in industry are not necessarily any more trustworthy. The biggest and most suspicious missing information for me, is in the actions of AF. My consipiracy theories ? - below:


AF released new UAS procedure days after the crash - with what changes and why ? - we are not told. Think we'll ever be ?

Rumour posted on these threads was that based on the ACARS info only (all they had at the time) they threw the scenario at line crews in the sim, and they crashed. Where are the reports of those sim tests ? What could the industry be learning from the debriefs ? Silence. Information suppressed. Clearly no lessons to learn... or just too embarrassing for AF ?

Which airlines pushed back against the AI recommendation for pitot change - was it just AF or others too ? Did others put pressure on Airbus via AF ? Where was the regulator in all that - just letting them sort a safety mod out amongst themselves when the cash flow was convenient ? Think we'll ever find out ?

AF pushed back against the pitot change because they wanted proof the new ones were better. Maybe that doesn't hang them, but in the meantime they flew on with known-bad pitots. Who signed off on that risk and decision ? Where is the risk assessment for not replacing the pitots ? Does it say "procedures and crew will handle UAS" ? Did they quality check said procedures and crew in assessing that risk ? [the crews that allegedly failed to handle UAS in sim afterwards, and the procedure so well written that pilots on here with all the time in the world to analyse it can't even agree what it meant]. You reckon we're going to see that assessment from AF ? Ya think maybe it might be otherwise engaged in a meeting with Mr Shredder (if it ever existed) ?

Then there's that cross-industry working group on stall. Conveniently reporting just after BEA (but maybe not the public) find out that 447 was another stall - so not to worry, look we've already found and fixed the problem... But look at that document. Target audience - line pilots. Content - pretty diagrams showing what AOA is. WTF ??? You mean line pilots don't know that ??? Repeated statements that stall is an AOA problem, not airspeed. WTF ??? You mean line pilots have been trained that stall is purely about speed ?? And conditioned not to lose altitude in stall for fear of failing the check ?

Pilots:
a) not trained to know what AOA is (hence no need for airlines to order the AOA display option)
b) trained that stall is about airspeed (going too slow)
c) trained not to lose alt in stall (pull up)

Result:
"stall stall". "I'm in TOGA". "We've got the engines". [Pulls back. Why aren't we going up?]


Oh, and after all that rant, yes, there was something wrong with the plane too. The pitots were a bit s**t in bad weather. As we've known for 2 yrs, remedial action taken, and as AF already knew before the event - because Airbus told them, proactively. Also, if you take the plane so far outside the envelope that no mfr engineer or test pilot or sim can tell you what will happen... some of the warning logic turns out to be screwy. And, er, that's it. No control reversal or controls ineffective (actually I'm not 100% sure on those), no departure into spin, no bits falling off... In fact following stall, plane did better than might be expected.


End of the day, AF litany is "the pilots did as they were trained". Yep. That's because, in response to a single instrument failure, you trained them to crash.

And that, sir, is the real scandal, that's what needs fixing - way before looking at stall warning logic at 30deg+ AOA. And by all acounts it is an industry wide problem, not just AF.

[Lyman]

infrequentflyer789

Without exception, exactly so. We knew all that, and the lack of redress/mitigation is another hole in the ground. My expectations are far too high.

If the numb, led by the greedy, supported by the regulator can keep those chain saws juggled, how can anyone expect to see actual improvements in the logic/airframe? One can't.

By the way, I have been trying to herd as many as I can back to the 20 seconds around a/p drop, mostly without success. So I completely agree that the interminable wheel action of the STALL, TOGA, "SUPERSTALL" brigade is an abject waste.

Are we truly in that deep?

Whether 447 oversped or no, we see it in action elsewhere, and it debriefs as some form of "best guess" remediation, by those who are demonstrably unclear on the concept.

We should be encouraged: Airbus did "Consult with Pilots"......

[philip2412]

a few weeks ago i have ask a question,meant to be answered by lyman.
did he answer it ?
no
am i surprised he did`nt ?
yes,because he reacts to every post immediatley and the anwer was only "yes" or "no".
no,because he had his reason not to answer.


soonce again:

do you think every commercial pilot on the whole wide world would have put AF447 into a climb to the stars ?

[HazelNuts39]

BEA no.3, Appendix 1: 2 h 12 min 04 - 2 h 12 min 07 :::
The airbrakes are controlled and deployed. ::: (PF - HN39) I have the impression that we have some crazy speed no what do you think?

[Ian W]

Quote:
Originally Posted by Ian W
Unfortunately, people who disbelieve the existence of cognitive overload have been allowed to design, test and implement aircraft systems. Setting up the potential for just the type of human factors caused accident that we have seen in AF447.

Originally Posted by Dozywannabe
That is a complete falsehood. Half the reason for the somewhat arcane annunciation logic employed in modern airliners is for the precise reason that cognitive overload is so feared and to be avoided. This is why Stall Warning quite literally trumps a whole host of others.

If you read my original post I proposed that you watched the YouTube video of the three crew in a landing aircraft not noticing the undercarriage up warning horn. Landing with undercarriage up is dangerous :This is why [undercarriage up] Warning quite literally trumps a whole host of others"

The crew in the YouTube video were just doing a routine landing and they had a cognitive overload. It can happen the next time you try to talk on a hands-free cell phone and drive. It is almost certain to happen immediately after an automation failure and 'automation surprise'. The reason stick pushers and shakers work better than an aural warning is that they are transmitted to the brain through the haptic channel. Just like when you are concentrating on something and you 'don't hear' someone talking to you - but you react immediately if they tap you on the shoulder.

Now the question to be addressed is _why_ did all three pilots react like this. just like the crew in that YouTube video. The fact that in both cases a full crew disregard an urgent aural warning should be an indication of a cognitive problem with aural warnings. Could it be that certain character types are more susceptible to cognitive tunneling when given more workload or in non-normal situations? Perhaps there was a lack of training in a particular aspect such as flying in alternate law at cruise level - so attention was tunneled to that task?

Whatever the reason was for them ignoring what to an observer is a warning that "quite literally trumps all others" - it shows that this type of warning can remain unnoticed by crews. This cognitive issue needs to be considered at the design stage and may result in a requirement for crew selection or specific (re)training.

Blaming the three pilots and ignoring the problem won't make it go away.

[Clandestino]

Please explain how a ROD of 10,000 per min (about 98 kts) is not sufficient to validate the stall warning.Pitot probes are fixed pointing forwards and were so ever since there were first installed on the aeroplane. They don't handle extreme AoAs well, such as were met in AF447 case. So far no one has come with a good reason why should they be swiveling or gimballed so they can detect downward speed - we use VSI's for that.

Worked for me and thousands of Viper pilots. Viper is supersonic single-engine aroplane with cropped delta wing plus chines. It has 1/5 of A330 installed thrust and 1/12 of its weight. A330 and F-16 have very different mission profiles, maneuverability/stability and stall characteristics. What works for one is not necessarily useful on the other.

So the Airbus designers installed the probes that don't work so far outside the flight envelope that noone even had an idea that aeroplane is capable of going that far out. Also they meet all certification criteria but in use get clogged in conditions we don't even know what they are. Welcome to the real world.

Overload a cognitive channel and NOTHING else will be processed by itHuman beings don't have cognitive channels. You might try improving your theory by including sensory channels in it. However, I doubt that pilots "hearing channels" were overloaded with anything else when stall warning went off.
There is a famous experiment where a team of observers of a basket ball match did not notice a man in a gorilla suit on the basket ball court. BS. It's not an experiment, it's an instructional video most pilot have seen at one or another CRM lecture.
people who disbelieve the existence of cognitive overload have been allowed to design, test and implement aircraft systems. Nope. They really know a lot about cognitive overload, they just choose not to believe any unfounded theory about it, put forward by zealous and ignorant.

1) Does anyone know why AP disconnected at 02:10:05 ?
(...)
I do not see any discrepancy between the two recorded AS before, at least, 02:10:07.5.Most probably because pitot2 succumbed to icing first. As the pilot in the right hand seat was designated PF, AP2 connected to ADR2 was engaged. Recorded speeds are from ADRs 1 and 3, which meets legal minima of two speeds been recorded.

Investigation of other UAS events was made easier by other crews bringing the aeroplane back unscathed to earth and with it the QAR, which records far more parameters but doesn't have to comply with survivability requirements applicable to FDR.

Of course ... Nevertheless they do not share all the facts starting with data and won’t necessarily feel the need to share all of their analysis, with Clandestino or CONF iture.I don't know about you sir, but I am not of such importance to be addressed direct by the investigation authorities. Rather I read their investigation reports that are made public and open to everyone's scrutiny. Their sole purpose is improving the aviation safety through disseminating information. They're not there to assign the blame or responsibility to anyone or anything and are not supposed to have any entertainment value. To understand and make good use of them, one needs to understand aeronautics well. To paraphrase Euclid: "There is no royal way to aeronautics".

Approaching accident reports with mind so open that the brains fall out is not conductive to learning anything from them. Lot of posts here remind me of an aphorism made by certain Teutonic, mustached gentleman:

The worst readers are those who proceed like plundering soldiers: they pick up a few things they can use, soil and confuse the rest, and blaspheme the whole.

[DozyWannabe]

Blaming the three pilots and ignoring the problem won't make it go away.

Again, name me a single person on this thread who is doing so. Even the BEA aren't!

[OK465]

A330 and F-16 have very different mission profiles, maneuverability/stability and stall characteristics. What works for one is not necessarily useful on the other.(my bold)

With respect to the very different stall characteristics, you know this to be true how?

[DozyWannabe]

Well, for a start the A330's airframe is designed to be a stable platform under normal flight conditions, and judging by the stall profile remains relatively stable in stall conditions too. The F-16 on the other hand is not stable without computer assistance even under normal flight conditions.

[Lyman]

When a/c is STALLED, do the F-16's stabilators migrate to, and remain at, FULLNU?

[Clandestino]

F-16:
http://www.militarypower.com.br/avi-F16-01.jpg



Airbus 330:

http://static.guim.co.uk/sys-images/Guardian/About/General/2009/6/1/1243859585912/An-Air-France-Airbus-A330-001.jpg

You've guessed it right... it's an aspect ratio. :E

[Lyman]

That's roll, then, what about the close couple?

[OK465]

Nice pictures.

[Lonewolf_50]

The difference I spotted immediately was ... no Frenchman at the controls of the Viper. :E


Nice pics.

Perhaps the A330 should have crosshairs superimposed, since our Russian readers might not recoginze a commercial aircraft without one ... (KAL 007 reference, and yes, I know it wasn't an A330 ... )

And now

Coat, hat, doorway ... Taxi!!!!! :eek:

[ihg]

Spot the difference!

well, that might bring back scales;
Photos: Airbus A330-322 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Belgium---Air/Airbus-A330-322/1765484/L/&sid=d214f13a7fafcf014834a07476dffa14)

[Zorin_75]

Perhaps the A330 should have crosshairs superimposed, since our Russian readers might not recoginze a commercial aircraft without one ... (KAL 007 reference, and yes, I know it wasn't an A330 ... )
I'm not sure I'd point my finger in that direction when talking about downing civilian Airbuses...

[Lyman]

Very unfortunate choice wolf.

[DozyWannabe]

I'm not sure I'd point my finger in that direction when talking about downing civilian Airbuses...

To clarify:

USA : 1 (Iran Air A300)
Iraqi insurgents : 0 (Despite an attempt on a DHL A300)

[Lyman]

philip2412 (re: #938)

"Does Lyman think that all commercial pilots in the world would start a climb to the stars?"

Sorry, I took that for rhetorical insult. 2nd look shows it to be a sincere attempt at insult.

No pilot would initiate such a climb, obviously. Your reference to the "intention" of 'to the stars' makes it ridiculous.......


These guys did not do so. Nor would anyone.

[VGCM66]

It is not the flying machines but the pilots and it is happening all over.

Accident: South East T154 at Moscow on Dec 4th 2010, two of three engines out in flight (http://avherald.com/h?article=4342e2dc/0003&opt=0)

Two assertions but only one is true:

"A good pilot is a well trained pilot."

"A well trained pilot is a good pilot."

One is not necessarily so. Can you guess which one?

[Lonewolf_50]

How interesting, the response to a jest.

This if off topic, but, in the course of the jest, please recall that there was NO visual ID in the Vincennes / AB300 incident, and while there was a VISUAL ID in the KAL 007. Given that we were talking about pictures, do you wonder at why I said it thusly? "since our Russian readers might not recoginze a commercial aircraft" (again, this is a jest) which might imply actually looking at an aircraft with a Mk 1 Mod 0 eyeball.

By the way, Zorin, you will find that KAL 007 was a Boeing aircraft- a 747. (Does it occur to you that this is why I put, in parens, the bit about it not being an A330?) Your attempted riposte might have worked better with an understanding of the facts.

In any case, Clandestino posted nice pics, so off we go, back to the discussion about ... an Airbus 330 that tied the low altitude record over the Atlantic Ocean. (And perhaps setting a record for negative altitude? :p)

[GarageYears]

Can we please get back on point? The last 5 or 6 posts or whatever are quite irrelevant and, if there was an attempt at humor, I'd venture sadly very misplaced.

[gums]

Nice pics. Best-looking jet I ever flew. And PLZ note the lack of a "PNF" or the ability to leave the cockpit and take a nap.

The Viper could not enter a stall in the conventional sense due to the AoA versus Gee pitch command implementation. The AoA limit was intentionally placed at 27 degrees to allow full roll commands at that value without fear of a departure. That's with A2A configuration. With bombs and such it was a different story and our AoA limit was reduced to about 18 deg and roll command was also reduced.

So the way you got to the "deep stall" was to be clever, or stoopid, and command a max roll rate when slow, but not necessarily "riding the limiter". So you could "rate" the pitch thru the limiter and also introduce some roll-coupling for added measure. However, several of the first "deep stall" incidents resulted from climbing at a high pitch attitude while holding the one gee basic trim command. If you slowed down quickly enough, then the stabilators ran outta nose down authority - about 50 deg AoA, and the pitch moment coefficient was such that you could not lower the nose.

The Airbus deep "stall" ( can't say it's a "deep stall" such as the Viper had or the T-tail airliners) is still not clearly defined. We don't have a good graph of the pitch moment coefficients or the amount of control authority with the THS in full nose down position at extremely high AoA. What we DO HAVE is one test point that implies the A330 can remain in a stalled condition when the THS is positioned for a full nose up command AND the pilot is commanding nose up - AF447.

The AF447 maneuver closely resembles the Viper entry conditions I described. Fly nose up with decreasing airspeed and then add the THS movement to full nose up command and Voila! Fly thru the AoA protection and you're there. And I am still not convinced that the AoA protection was working normally.

I still maintain that AoA inputs can be of value even at very slow speeds. In the Viper, you hit the gee limit before the AoA limit at cruise speeds and higher. This was based on the dynamic pressure at the time. So we could get 9 gees at about 360 KCAS and 15 degrees AoA. If you "rode the limiter" down to one gee, you were at 27 deg AoA. You were also very slow, maybe 140 knots or so.

That's all for now, and thot we went thru this before.

[PuraVidaTransport]

From looking at the data in the latest report, sure looks to me like the pilot pulling nose up (and the THS at full nose up) were not enough to keep the aircraft in the nose-high attitude and thus, the full stall.

Notice the ENGINE THRUST traces vs. attitude during the stall. Every time the pilots pulled back on the throttle, the nose fell through as it should. The engines (thrust) was what kept them in the nose up attitude and in the stall, not the pilot sidestick commands OR the THS.

[Clandestino]

The Viper could not enter a stall in the conventional sense due to the AoA versus Gee pitch command implementation. It's pretty alike to the way the Alpha protection works on FBW Airbuses. However, Viper is supersonic combat aircraft and A330 is long-range passenger transport, so their design specifications and sensors/flight controls architecture are certain to be different, even if end results are somewhat similar.

And I am still not convinced that the AoA protection was working normally.That's the point. It worked as designed - it shut itself down. Why in the hell would it do that? People more intimately acquainted with intricacies of Airbus protection systems might come up with more precise and more comprehensive answers, I'll just stick to one that first crossed my mind: AoA max of Airbus wing is quite affected by the mach number so AoA prot needs to "know" actual mach number to modify its activation threshold. threshold applicable to cruise might restrict flare capability, threshold applicable to approach would not activate protection at high mach before the aeroplane is stalled (provided G limit is not reached first, that is). In situation where there was no valid TAS, and therefore no mach, there could be no protection adjustment so alpha prot was lost.

Loss of protections is not such a stark condition as its name would imply. Airbus protections don't interfere with flying as long as one stays well within the envelope and are only very seldom met during regular flying. When they're gone, one can rely only on one's own wits to keep him from transgressing outside the flight envelope but that's what pilots have been doing since there were first pilots.

All the talking about three different aeroplanes in three different control laws is pretty non-sensical. Aerodynamically and performance-wise, it is the same aeroplane and flight controls feel is not much different. At least it is so in level D sim and I yet have to come across level D that doesn't closely match the aeroplane's behaviour - within the territory where test pilots dared to go.

The engines (thrust) was what kept them in the nose up attitude and in the stall, not the pilot sidestick commands OR the THS. Chances are, it were all three that kept it stalled but I doubt we'll find test pilot brave enough to check exactly how much each of them contributed to the demise of 447.

[gums]

Trust me, I am very familiar with mach and AoA. I also appreciate a design of the fly-by-wire control laws that takes into account of all the aero crapola.

Until you have supersonic flow over the entire wing, then the basic AoA works like we expect. Once supersonic, we have a different shock wave flow pattern, hence the "diamond" configuration of some fighters' wings. We no longer have a "normal" shockwave front and have different pressures on the bottom and top and even parts thereof. The diamond airfoils have at least two shockwave "fronts" on top and bottom. So moving the wing or the stab changes the pressures and we get pitch authority. Ailerons have a more serious problem, but the clever engineers have figured that out.

The Airbus AoA versus mach equation seems very conservative, and I would bet my life on the AoA before the overspeed warnings and whatever "laws" and warnings that are implemented. I seriously doubt you could rip the wings off of the A330 if you exceeded the "protections"/"warning" values by .05 mach or 30 or 40 knots EAS/CAS/IAS. You might get some wing "flapping" as the shockwaves got in the way of the ailerons and spoliers, but big deal.

The shockwaves over the THS would be more of a concern to me, and I have provided Yeager's war story and the design changes to all fighters that resulted in all-moving horizontal stabilizers ( not the 'bus with a conventional elevator and the THS).

In all defense of the basic Airbus aero design, the sucker looks like an outstanding platform without all the FBW protections and plethora of alternate laws and such. i would take that beast and wring it out any day even in the "direct law". OTOH, I fully understand the FBW control surface movements and rate and mechanical/aero limts that are implemented. I would not like to fly the beast with a simple electric command of the control surface position and rate of movement. But I could!!!

As all know here, I have an extreme problem with all the "autopilot" functions and "protections" that Airbus has implemented that can get in the way of basic airmanship by the pilots and the basic aero characteristics of the jet. The jet appears to be well-designed.

[PuraVidaTransport]

Clandestino - If you will look at the FDR traces in the latest report, you will notice that at 2:11:45 the pilot had full nose-up sidestick inputs, the THS was in the process of moving to full nose up and the aircraft was fully stalled with a nose-up attitude of about 15 degrees and an AOA greater than 30 degrees. A few seconds later, the N1 falls off, bottoming out at about 2:12:07 around 60%. During this time, PF had the sidestick full back and the THS was almost full nose up BUT the attitude decreased from 15 degrees nose up to 10 degrees nose down in about 10 seconds.

Later, at around 2:14:05, with both sidesticks in full back (nose up) and the THS at full nose up, a decrees in N1 reduced the pitch from 20 degrees nose up to 5 degrees nose down. For me, this proves what was keeping the nose pitched up was the thrust not any flight control inputs or the THS because EVERY time thrust was reduced, the nose fell despite the PF actions (inputs and THS).

Every other instance where the nose started to fall were control inputs showing even with the full thrust, there was enough control to get the nose down.

[Linktrained]

Clandestino #960

A "brave test pilot " has done some of the tests. Jacques Roysay in Airbus Safety First quotes a " practical test done in flight, and well reproduced in the simulator..." of an A340 in various approaches with the Stall Warning on, at low level, going from flight idle to TOGA.
See page 8 Para 8 ( Home (http://www.ukfsc.co.uk/) ) January 2011 issue.
( I suppose that it was probably not at night, in/near a Cb. and suddenly...)

[mm43]

The direct link to the January 2011 Airbus Safety First magazine is here (http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Airbus%20Safety%20First%20Mag%20-January%202011.pdf).

[jcjeant]

Hi,

Some press release ... (BEA accused by a family lawyer)
Vol Rio-Paris: des familles de victimes saisissent la juge d'instruction - Libération (http://www.liberation.fr/depeches/01012361598-vol-rio-paris-des-familles-de-victimes-saisissent-la-juge-d-instruction)
Google Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.liberation.fr%2Fdepeches%2F01012361598-vol-rio-paris-des-familles-de-victimes-saisissent-la-juge-d-instruction&act=url)

[DozyWannabe]

The article (and the lawyer concerned) seems to be saying in a roundabout way that the pitot probes should have been subject to an AD rather than a service bulletin, but neglects to mention that it was AF who had chosen to delay the replacement until the next scheduled service interval - in defiance of Airbus's own recommendation that the replacement be carried out as soon as practically possible. It also neglects to mention that BUSS was a new option (that AF had elected not to fit), and the research that caused its development was also very new at the time of the AF447 crash.

It also makes the assertion that the BEA have been implicitly blaming the pilots which is not the case - if anything, the interim reports and press releases since the retrieval of the flight recorders have tended to imply a problem within Air France and the industry as a whole.

So basically it's an ambulance chaser going after bigger money by trying to get the aircraft (and it's manufacturer) blamed, or assigned more responsibility than they are already expected to share due to the pitot tube issues - they've produced no proof at all that the BEA are anything but on the level here.

This is no different than the cases where ambulance chasers in the past have tried to get manufacturers (not just Airbus) in the frame legally when the reports and evidence say there is no reason to do so as yet.

[Lyman]

That certainly is a point of view, and well taken. The problem with it is that it reeks of the type of rhetoric the ambulance chaser is accused of using.

pot/kettle


Hindsight and the accusation of the use thereof cuts both ways. This accident makes painfully clear some things no one wants to look at, least of all a partisan.

As a flyer, I take note of the record. With upwards of three dozen UAS events, each handled in an ad hoc manner, the replacement of the Probes should have been an emergency AD, imo. One would hope that those in charge would have seen it that way after the first dozen or so events.

This alone frames the problem well. It also makes clear the approach used by the Line, the Manufacturer, and the Regulator: Roll with the data, modify procedures, and alert the crews.

Mixing bile with resentment does not produce a clear product.

Lawyers do what they do, and in doing so, present a kind of eeyew predictability that has an aroma of integrity.

It is such a shame that while the three principals present as having integrity, they do not, and seemingly, they have their cheering section as well.

The worst of this crowd is the supposed "independent" Investigator/Regulator. It is to laugh out loud, this hypocrisy.

Hindsight should destroy this practice; can there be agreement?

[jcjeant]

Hi,

AIR FRANCE EN QUETE DE SECURITE - YouTube

To see on France 5 TV network this Sunday
Guide des programmes - France 5 (http://www.france5.fr/programmes/index-fr.php?affnum=011414&prgnum=0&numcase=42&date=25-09-2011&plage=1900-2400)

52 'documentary directed by Fabrice Amedeo and Veronique Préault and produced by Galaxy Press, with the participation of France Televisions and Planet.

Air France is one of the largest companies in the world, but it displays in aviation safety, a poor track record with three major accidents in less than ten years. The crash of the Rio-Paris in June 2009, which caused the disappearance of 228 people, the explosion of an aircraft landing in Toronto in 2005, which has miraculously no one was injured and the accident Concorde takeoff in 2000, which was 113 dead. They made the French company plunged into the depths of the world ranking security. How to explain this series of disasters? Could they be avoided? Do you always expect the worst to react? Aviation Safety at Air France is one of the biggest taboos of French industry. With this documentary, for the first time, people start to speak, witnesses speak, retired from the company whistleblowers. The investigation goes back to the track unreported incidents in recent months, where we came close to disaster. For the first time, Air France has played the game of transparency. The company has agreed to allow filming Focus on the drivers, which symbolize the company's thinking on the major changes necessary for safety. From internal documents and testimony shocks, this film breaks the silence, of setting in the aviation industry.
(Programme for teletext subtitles for the deaf and hard of hearing)

[DozyWannabe]

As a flyer, I take note of the record. With upwards of three dozen UAS events, each handled in an ad hoc manner, the replacement of the Probes should have been an emergency AD, imo. One would hope that those in charge would have seen it that way after the first dozen or so events.

The manufacturer recommended the SB be applied as soon as practically possible. AF elected to take their time over it. An AD would have resulted in the grounding of all A330 and A340s, which could be argued would have been overkill given that none of the previous incidents had resulted in an emergency situation. Again, it looks like the ball is more in AF's court than Airbus's - though as I've said before Airbus will carry some responsibility for fitting those pitot tubes in the first place (despite the fact that they passed certification). Airbus said "fix this", AF decided to delay - how can Airbus be held responsible for AF's decision?

To re-state the facts as they were prior to this accident is not "partisan" in any way - facts are facts. To state that there was no emergency situation beforehand is not cheerleading, it is just honesty.

Put another way - before this happened, if I as a mere software engineer had suggested that a 2-man relief crew with a combined number of hours in excess of 6,000 was unable to identify - let alone recover from - a high-altitude stall, I'd have been pilloried and laughed off the forum for impugning the abilities of professional airline pilots. Now we know that if the training is inadequate, that can indeed happen and the ripples of that revelation will be doing their work throughout the industry for some time to come.

In a perfect world, every incident that revealed a minor technical problem would result in an AD until the problem was fixed. But neither the world nor the aviation industry is perfect, and real politik will have to be taken into account. This situation is a million miles from the DC-10 cargo door issue (where an AD was appropriate), because the loss of pitot data results in neither structural damage nor an uncontrollable aircraft. The accusation of political machinations also rings hollow, because Airbus were not at the time in existential danger from the issue - the A330 and A340 were already a commercial success and there was little danger of jeopardising their continued success.

[Lyman]

When there is an "as supplied" issue, one that creates a safety problem, the standard of the industry is to recall the equipment, or arrange for a refit or replacement. Air France is not in the Airframe business, and Pitot Tubes are not "livery". Airbus is clearly in the wrong, though I see your point, I simply do not agree.

"Void if altered or modified". Ring a Bell? Even with an automobile, a conveyance that can pull over to the side of the road, the vehicle is recalled to the location of Manufacturer's representative, for an approved repair or replacement of the offending kit.

The arrangement is demonstrably full of "Oh, I thought you'd take care of that" nonsense that allows for keeping in service, equipment that has demonstrably fallen short of safety minima.

You think loss of indicated airspeed is not an emergency? The only pilot who may be surprised with a life and death issue must be in test only. UAS got to be "acceptable risk", I think it has been shown that the state of affairs shows it not to be acceptable at all. Not knowing if a STALL WARN is correct? Not knowing that re select of autopilot might initiate a wild climb? These data WERE KNOWN and the pitots sat on the Bench.

You are satisfied that Airbus is free of responsibility once AF has the SB? Two things of utmost importance are absent from that opinion.

Initiative, and Follow-up.

Regulator, Airbus, Air France:

This unholy triumvirate has killed 228 people.

So now the Overspeed Protection is the latest wiggle on the worm? The lack of forthright clarity in understanding of systems by the pilots here on thread is disturbing. Someone, somewhere must know what's up.

Do they?


ps. Be careful about constantly returning to the "ill-trained" crew meme.

We do NOT know that, and pending the accuracy and content of further data, it is a thin branch on which to stand. Saying otherwise begs the lie for BEA "Not impugning the crew" with cherry picked releases. imho.

best regards

[DozyWannabe]

Lyman, I said I wasn't going to get into this with you any more.

You are satisfied that Airbus is free of responsibility once AF has the SB? Two things of utmost importance are absent from that opinion.

No, that's quoting me selectively - I said Airbus cannot be held responsible for the somewhat lackadaisical approach to replacing the pitot tubes that AF took. Airbus are still on the hook for the pitot tube problems in the first place.

It was an unfortunate situation, but there was no cover-up here, no "unholy triumvirate". This was a problem that had a procedural solution while the mechanical solution was being applied - just like the long-dormant software bug in the 747-400's control logic that the BA crew recently discovered, a fix was designed and was in the process of being rolled out without having to ground the fleet. This is not unusual, it's just how aviation works.

Anyway, enough.

[Lyman]

When a critical repair is delegated to others, no matter the provenance, two things:

Responsibility cannot be shrugged off, and a follow on is required for many reasons. It is not so simple as you say. Suffice to say Airbus was obviously satisfied with the protocol for replacement, and they should have been more careful.

Having identified the problem, it is not possible for Airbus to absolve responsibility for its mitigation, as we will see.

Thanks for your time and patience.

[jcjeant]

Hi,

DW
But neither the world nor the aviation industry is perfect, and real politik will have to be taken into accountCiel orageux sur l (http://www.liberation.fr/societe/01012352624-ciel-orageux-sur-l-independance)

Google Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.liberation.fr%2Fsociete%2F01012352624-ciel-orageux-sur-l-independance&act=url)

It's unfortunate that BEA took also in accounts real politik and by doing so become a not credible or independent investigation office

Tutelle. La loi garantit son «indépendance», mais sans lui en donner les moyens, car c’est un service de la Direction générale de l’aviation civile (DGAC), elle-même sous tutelle du ministre des Transports. Or, le BEA est susceptible d’enquêter sur la DGAC, mais aussi sur Airbus et Air France, dont l’Etat est actionnaire. D’où les risques d’interventions et de conflits d’intérêts. Le crash du Concorde en 2000, à la suite d’un éclatement de pneus ayant perforé la voilure, est un cas d’école. Lors de l’instruction, un enquêteur du BEA, Michel Bourgeois, a rapporté avoir subi des pressions lors d’un incident similaire survenu sur l’avion en 1979 : «On nous a dit de rester tranquilles et de ne pas embêter Air France.» Le juge d’instruction a également constaté que les incidents de pneus «pouvaient provoquer des trous de dimensions importantes» dans les ailes, ce qui a «semble-t-il, gêné le constructeur». Effectivement : EADS (maison mère d’Airbus) a demandé en août 2000 au BEA d’ajouter dans son rapport que les trous étaient «de petite dimension». Ce que le BEA a accepté. Mais on ne l’a su que dix ans plus tard. Cet exemple et celui du Rio-Paris (lire ci-contre) mettent en cause les méthodes du BEA, souvent critiqué pour son «manque de transparence». Il envoie son rapport avant publication aux acteurs concernés, sans jamais dire s’il a pris en compte leurs observations dans sa rédaction finale. A la différence de la Cour des comptes, qui ne modifie pas ses rapports, mais publie en annexe la réponse des organismes qu’elle met en cause.Guardianship. The law guarantees its "independence", but give him the means, because it is a service of the Directorate General of Civil Aviation (DGAC), which in turn supervised by the Minister of Transport. However, the BEA is likely to investigate the DGAC, but also on Airbus and Air France, which the state is a shareholder. Where the risks of interventions and conflicts of interest. The Concorde crash in 2000, following a tire burst having punctured the wing, is a textbook case. At the trial, an investigator from the BEA, Michel Bourgeois, reported being pressured in a similar incident on the plane in 1979: "We were told to be quiet and not bother Air France. "The judge also found that incidents of tires" could cause large size holes "in the wings, which" apparently he embarrassed the manufacturer. " Actually: EADS (Airbus' parent company) has requested in August 2000 to add the BEA in its report that the holes were "small." What the BEA agreed. But we did know that ten years later. This example and that of the Rio-Paris (see below cons) involved the methods of the BEA, often criticized for its "lack of transparency." He sends his report before publication to stakeholders, without ever saying it took into account comments in its final drafting. Unlike the Court of Auditors, which does not modify its reports, published in the appendix but the response of the organizations it involves.

[CONF iture]

An AD would have resulted in the grounding of all A330 and A340s
No.
The compliance time for an AD has not to be immediate.

Airbus said "fix this", AF decided to delay
If Airbus had said that, it would have been an AD.

[DozyWannabe]

@jcj - The BEA is a different institution than it was in 1979. The world learned the hard way what happens when accident investigation and repair procedures are stymied for political reasons. They were so afraid of being seen as biased following AF296 that they invited the NTSB along as impartial observers following the Air Inter crash, and to my knowledge the NTSB had nothing bad to say about thir methods. I'd like to know the source of the "large" vs. "small" argument in 2000 regarding Concorde, and I'd also like to know more details about what that means. To me, a "large" hole would imply a significant enough size to reduce lift, which never happened due to a tyre burst.

@CONF

A Service Bulletin also says "fix this" - the difference between that and an AD is that the aircraft should not be considered airworthy without the repair being done promptly (and supervised by the regulatory authority) in the case of the latter, which was not the case based on the evidence prior to AF447.

(PS. My question here : http://www.pprune.org/rumours-news/388573-pilot-handling-skills-under-threat-says-airbus-24.html#post6661648 remains unanswered - did you see it, and would you like to give it a go?)

Airbus covered as many bases as possible by releasing the Service Bulletin and advice to pilots for procedures to follow in the case of a UAS incident. These procedures were not followed in the case of AF447, whether due to human factors, poor training or a combination of the two. Whatever the outcome of the debate over the stall warning logic at low speed, the fact is that the aircraft would not have stalled in the first place had proper airmanship been applied, and no matter how many some may wish for evidence supporting the automatics being behind the initial zoom climb, that evidence does not exist. Instead there's plenty of evidence supporting manual input causing the zoom climb, followed by a failure to diagnose stall and an attempt to "power out" of the upset, and unless you're prepared to provide evidence that the BEA have somehow falsified the flight recorder traces, then that is the most likely conclusion.

The BEA are not content to "blame the pilots" and leave it at that, however and the presence of an in-depth human factors investigation proves that - so to say that they are protecting the regulator, manufacturer or airline is nothing short of a big, fat lie. As I said earlier, the A330 is a success and the project has broken even - what is there to "protect"?

[jcjeant]

Hi,

To me, a "large" hole would imply a significant enough size to reduce lift, which never happened due to a tyre burst.Nothing to do with lift .. but with flow
The Concorde problem was hole (s) in the fuel tank !
And this happened to Concorde (Washington event) long time before the Gonesse accident.

The BEA is a different institution than it was in 1979The BEA is exactly the same institution today than in 1979
a service of the Directorate General of Civil Aviation (DGAC), which in turn supervised by the Minister of TransportSame duties .. same hierarchy ...
Or tell me what is changed .... ?

[Lyman]

"A Big Fat Lie". If anyone has charged BEA with falsification, where is it? To my knowledge they have merely created a climate of doubt, absent the full disclosure of recorded data.

There is no evidence that the autos helped STALL the a/c, neither is there exculpatory evidence. None of either kind have been disclosed.

Since there have been well documented instances of a/c behaviour that did create dangerous flights, it would seem in the best interests of all to see, read, and hear the (complete) CVR/FDR.

Until then, the argument isn't worth the blood flow.

Except to say. Read the BEA report re: THS 'movement' at the start of the climb post handoff. Several times if necessary. Very odd, and very erm, "well-devised".

[Da-20 monkey]

Hi,

May I ask some Airbus- related questions out of general interest?

1. Do Airbus flight controls use artificial feel units?

2. If they do, how would it behave in a scenario with unusual airspeed readings, like AF 447 had? Because an AFU needs airspeed input right?

3. Is this of any significance?

Thanks

[DozyWannabe]

@DA-20 monkey:

Nope - Airbus sidestick feel is implemented via passive springing. It takes more effort to deflect the further you move it from the centre, but there's no force-feedback as such.

[CONF iture]

A Service Bulletin also says "fix this" - the difference between that and an AD is that the aircraft should not be considered airworthy without the repair being done promptly (and supervised by the regulatory authority) in the case of the latter, which was not the case based on the evidence prior to AF447.
No Dozy.
Service Bulletin = You may fix this
Airworthiness Directive = Fix this (but that does not necessarily require immediate compliance prior next flight - You might as well have a full year compliance time)

No justification to state anything like this :
"An AD would have resulted in the grounding of all A330 and A340s"

[Lyman]

Airworthiness Directive. The owner is ordered to make the repair, with a schedule supplied by the Regulating Authority. Unlikely that the pitot r/r would have involved a RTB anyway. Clearly, the Regulator was good with the "at your leisure" pace set by Airbus. No one entity can be singled out for this egregious lapse in safety concerns. To me, all three are equally culpable.

After BA038 went in, UAL discovered a non compliance issue with the fire Bottle #5 Inspection Record in their 777 fleet. They recalled all a/c back to station for an inspection, immediately. It was deferrable, but the line chose to exercise caution.

This foot dragging by AF with the pitots is classic backscratching. It is similar to the "negotiated" relaxation of the TRENT inspections on the Qantas 380 that led to an engine explosion.

It is a cordial, "adversarial" and a negotiated diminution of safety.

[DozyWannabe]

@CONF

I was referring back to "The DC-10 Case", where it states that an AD to replace the cargo doors would have resulted in the grounding of all DC-10s until the repair had been carried out. Perhaps the rules have changed since then, but that was my source material.

[hetfield]

1. Do Airbus flight controls use artificial feel units?

2. If they do, how would it behave in a scenario with unusual airspeed readings, like AF 447 had? Because an AFU needs airspeed input right?

3. Is this of any significance?Like dozy already answered modern airbus don't have artificial feel, A300/310 had.

IMHO this accident wolud NOT have happened with artificial feel.

[DozyWannabe]

The direct link to the January 2011 Airbus Safety First magazine is here (http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Airbus%20Safety%20First%20Mag%20-January%202011.pdf).

Finally got around to reading this - despite the occasional endearing translation error it's good stuff and surprisingly makes the AoA situation (which I must confess confused me when described in raw numbers) understandable to a maths/physics dolt like me.

On another note though, it does rather put a spoke in the wheel of those who are saying Airbus/BAE/DGAC are trying to sweep the issue of AF447 under the rug by blaming the pilots, because in the article Airbus come out and directly state that the previous procedures (which they helped develop) were inadequate and in some cases could make a developed stall worse - in short, they're admitting - in print - that they, along with the rest of the industry, screwed up to some degree.

[Mr Optimistic]

This seems a rather difficult 'take away'.

If the control column does not provide the
needed response, stabilizer trim may be necessary.
However, excessive use of trim can aggravate the
condition, or may result in loss of control or in high
structural loads.

How do you deetrmine the limit before it becomes 'excessive' ? Couldn't an easier rule of thumb be devised ? A simple instruction to check trim seems a more natural starting point.

[hetfield]

If the control column.........

What control column?

[DozyWannabe]

You're quoting from the "generic" recommendations, i.e not Airbus specific (the clue being the word "control column" as opposed to yoke or sidestick). I suspect the FCOM information per type will be more specific about how the trim should be used in that situation.

[JenCluse]

On 22 Sep/page 49 mm43 kindly posted the link to the Airbus Safety First magazine, with a follow-up link on page 50 by DozyWannabe. Thanks to both.

My reading of it has stalled (geddit?) at Issue 11, page 9, at the oh so simplistic stall condition & effects diagrams. They have been, of course, put together by Airbus, who IIRC only make one high-engined aircraft, the rest of their engines being underslung.

All well and good, but as happened on my initial 320 endorsement, people new to type will have come from low, on-longitudinal-centreline and high mounted engines, all of which require different stall recovery techniques, the range of which which these diagrams don't address.

At item 10, page 9, it is states that "

This generic procedure will be published as an annex to the FAA AC 120.
This new procedure has been established in the following spirit:
)- One single procedure to cover ALL stall conditions
)- Get rid of TOGA as first action
)- Focus on AoA reduction.

Bearing in mind that there will be strong recruitment pressures on airlines, and a probable need to accept less experienced aircrew, to cement the first item of this 'generic procedure' in legislation strikes me as a form of engineering conceit bordering on hubris, and will certainly bring with it deep industry-wide problems in the future.

Personally, I would require all trainees have to be exposed to the Victa 100 (not the higher powered versions, which were heavier on the controls) and be able to demonstate a continuous series of three loops without inducing stall buffet at *any point of the loop. It can & will 'bite' at *any speed and/or g-load if mishandled, and breeds a deep knowledge of airfoil behaviour that sticks with you. Cheap insurance. Oh yes, it also develops a fine 'touch', a la Gums early observations.

[infrequentflyer789]

My reading of it has stalled (geddit?) at Issue 11, page 9, at the oh so simplistic stall condition & effects diagrams. They have been, of course, put together by Airbus, who IIRC only make one high-engined aircraft, the rest of their engines being underslung.


That isn't quite correct, the Airbus magazine report is just one publication of the outputs from the FAA Stall Recovery Training Working Group. That included at least Airbus, Boeing, ATR, Embraer and probably some others too.

Some non-Airbus reference:

Flight Path Management (Expanded Version) | Flight Safety Foundation (http://flightsafety.org/asw/nov2010/flightpath.html)
Stop Stalling | Flight Safety Foundation (http://flightsafety.org/aerosafety-world-magazine/april-2011/stop-stalling)
http://flightsafety.org/asw/apr11/asw_apr11_p46-49.pdf

Yes, the simplistic diagrams don't inspire confidence, given the intended audience, however what is more scary is the conclusion (supported by various documents including from FAA) that the industry has been effectively teaching pilots to power out of a stall rather than put the nose down and start flying again.

This isn't an Airbus problem, and Airbus can only be part of the solution - though at least it looks like something is finally happening across the industry to fix this.

[Lonewolf_50]

IF789: if I may play devil's advocate for a moment.

Even when one is trying to "power out of a stall," one still has to control pitch to prevent restall. Pitch + Power = Performance still applies. Low to the ground, seems to me that there is a risk of negative training taking place if use of power and pitch to unstall isn't well taught.

How the recovery, or return to flight away from stall when one gets a stall warning, is taught is as important as what it taught.

[Lyman]

It was through Colgan/Buffalo that the more recent concerns re: training to STALL were made evident. Procedure (for an approach/STALL) was to advance throttles, and prevent altitude loss. This was trained as "maintaining back pressure", not increasing it. A loss of greater than 100 feet altitude was considered disqualifying.

And this was accepted training at low level.

Has the common perception of 447's crew STALL procedures been equated with "not losing altitude"? Has it morphed into "full back stick", with the STALL WARN activated for 54 seconds? One believes so, and what an outrageous position to 'push', absent full disclosure of all data.

At the last, when Captain suggests a Pull, ('Tire', in the French), pilot flying says, essentially, "I have been pulling back a long time already".
Without further elaboration by the investigators, this translates as an incorrect reaction to STALL. It most assuredly was not, since no recognition of STALL is demonstrated.

I suggest that leaving it at that, (as a non-response to the airframe's attitude) is grossly misleading, and infers a knowledge of the situation that either is non-existent, or, more likely, not released.

Here we bump into the most telling failure of the current "Investigatory" paradigm. With knowledge of problems in accepted procedures seemingly available, but 'hidden', they are not addressed, and the professional community is at a loss to make progress.

For fear of embarrassing an airline? An Airframer? This is unacceptable.

A profoundly important opportunity to increase knowledge and improve safety exists in the full and complete disclosure of 447's data. BEA are sitting on it. BEA make flying less than safe. It is my charge.

No, call it an accusation.

[DozyWannabe]

It doesn't matter what the response was, the fact is that they *were* stalled, and as part of the investigation (bolstered by the ColganAir accident), they discovered that approach to stall procedures and training were inadequate for dealing with a real stall.

Will the Asseline fanclub please explain to me why they are not also demanding the same release of raw data from NTSB and AAIB investigations as a matter of course?

@LW_50 - we've been through this many times before, so I'll keep it brief, but if the PF either did not hear or did not properly comprehend the PNF's callout of "Alternate Law" at the start of the sequence, he may have been subconsciously relying on the Normal Law protections to keep his AoA out of the danger zone.

[Lyman]

Indeed, I believe PF was in "Normal Law", figuratively, if not actually. In fact, It seems consistent with the rest of his flying, this 'reliance' on the a/c's Laws. I keep in mind that turbulence alone could have augmented his "shaky" stickwork; no one here has the chops to say this "mayonnaise" was indicative of poor flying. Bear in mind that Overspeed was his working hypothesis, and we know that can work in NL. So can the autopilot dropout in Normal Law, and remain so...... If he had Overspeed on his mind, and Normal Law as his mien, that would explain alot.

Someone has not considered how much the remaining data can add to the discussion about which he has made some remarkable conclusions. And this particular one not a pilot, as it were.

Dozy, the poor attempt at humor comes across as mere snark, and is beneath you.

"It doesn't matter what the response was...." That may be the single most salient remark in these 6 threads, all respect.

[Centrosphere]

Try Before You Fly: How Dreamliner Pilots Train Without Lifting Off | Autopia | Wired.com (http://www.wired.com/autopia/2011/09/787-flight-training/)

"Anyone who's flown a Boeing 777 can get up to speed with the 787 in as few as five days as the two airplanes share a type rating for pilots. A pilot with no experience in a Boeing airplane will need as long as 22 days to receive a type rating and master the 787."

Just wondering about the relationship between sim training and that "human factors" problem...

Disclaimer: I´m not even remotely trying to put this in AB vs Boeing perspective.

[Mr Optimistic]

I think it is possible to get to sophisticated about the 'human factors' problem. It is all very well talking about isolated detail (sidestick v yoke, angle of attack meter display), but I think the real underlying issue is the pyschological response which seems to have determined that something inexplicable was happening. In a straightforward, known, simple, deterministic system which you know doesn't embody millions of man hours of design, coding and testing, there are relatively few parameters and few possible control responses. The mental approach to problem solving in such a regime is happily constrained. In a system which you know (all that training, all those sub-modes, all those interactions and dependenciess to remember) to be complex, starting to understand the problem is polluted by the possibility that the complex intervening layer is behaving in a way which you either don't understand, or which has bust and gone outside its normal limits.

It doesn't require the complex system to in fact break, or for you to forget your training, to introduce the possibility that a stressed human mind trying to start to appreciate an unanticipated possibility never achieves sufficient confident to diagnose and then act. The awareness of a complex intervening layer is in itself sufficient to frustrate intelligent problem solving, at least in a timely way.

A 'big red button' which forced direct law, with direct law behaviour a set of memory items, would seem a reasonable last resort to offer a bemused crew.

Not forgetting appropriate display of unusual trim conditions and cancellation of any warning cancellations, naturally.