AF447 wreckage found

[Carjockey]

However, if the PF (or the 'system') stalls the aircraft at altitude and can't recover because the controls won't respond or the instruments don't indicate a stall or the PF's training is lacking; then IMHO that is NOT pilot error.

Of course it's not.

An opinion:

Is that that there are basic software design misconceptions, with regard to the interface between humans (pilots) and the aircraft automation, built into certain commercial passenger aircraft. These misconceptions have been compounded and endorsed (perhaps in misguided good faith) by certain airline operators who believe that they can reduce their 'pilot training' costs by using aircraft that can 'fly themselves'.

These airline operators would have a philosophy something like this:

Why waste money on over-training pilots if the aircraft automation can handle the aircraft in flight? We can just train our pilots to fully believe in the aircraft automated systems can't we? The systems cannot go wrong can they?

But maybe they can...

This aircraft went down 3.5 minutes after the AP disengaged and handed control to the PF, without apparently giving any indication to the PF as to why the AP disengaged.

A supposedly highly sophisticated aircraft automation system just gives up in a flight situation which it cannot handle and gives control to the humans on the flight deck without any indication as to why it did this? WTF!

Is there an SOP for the pilots to deal with this situation?

If so, can the SOP be effectively executed in less than 3.5 minutes (or before the aircraft falls out of the sky) and if not, why not?

These questions really bother me.

I cannot imagine how those guys on the flight deck felt or what they thought when confronted with this situation, not to mention what the passengers/CC went through, if they were (God forbid) ever really aware of their situation...

So how about we take all the software writers who conceived this system, the beancounters who drove it's implimentation and the managers who approved it, put them all on the same type aircraft in a identical situation (with the managers in the drivers seats) and just say 'OK, you have control guys'...

[jcjeant]

Hi,

The english translations of the original French BEA reports must be treated with caution. The BEA clearly states that the authoritative version is the original French copy.

Voiçi la version française .....

Entre 1 h 59 min 32 et 2 h 01 min 46 , le commandant de bord assiste au briefing entre
les deux copilotes, au cours duquel le PF dit notamment que « le petit peu de turbulence
que tu viens de voir […] on devrait trouver le même devant […] on est dans la couche
malheureusement on ne peut pas trop monter pour l’instant parce que la température
diminue moins vite que prévu » et que « le logon a échoué avec Dakar ». Le commandant
de bord quitte le poste de pilotage.

A 2 h 08 min 07 , le PNF propose « tu peux éventuellement prendre un peu à gauche […] ».
L’avion entame un léger virage à gauche ; la déviation par rapport à la route initialement
suivie est d’environ 12 degrés. Le niveau de turbulences augmente légèrement et
l’équipage décide de réduire le Mach vers 0,8.

So ,you can translate in english ...

The captain attended (assiste) the briefing
(the captain is there observing the discussion between the two pilots .. he don't take the lead of the discussion)
Or
J'assiste a un match de football
I attend a football match
Le verbe assiste n'a pas le sens d'assister en tant qu'aider
The verb has no meaning attends to attend as helping
EG:
Je t'assiste a lever ce meuble
I help thee to lift this furniture
Or
Je te porte assistance
I bring you support

If the captain is there for help it will be ...
Le capitaine apporte son assistance pendant le briefing
Captain assists during the briefing

Can you possibly or maybe (éventuellement) take a little to the left
(it's a proposition .. a polite suggestion .. he offer a choice to the PF .. it's not a order)

The sens of the sentences from french to english is exactly the same .......
The french language is full of words meaning the same thing ... c'est la finesse de la langue française

[Turbine D]

Re: Icing or Specifically Ice Crystals

rgbrock1,

Sorry about that, try this link:

http://icingalliance.org/meetings/RI...ersion_nss.pdf

[Level100]

French & English

jcjeant,

with all due respect, but to my taste SeenItAll's perception of the appropriate french-to-english translation is better than yours.
secondly, the way the weather avoidance is phased is a GOOD example of CRM,
polite phrasing is an important part of the game.

[jcjeant]

Hi,

with all due respect, but to my taste SeenItAll's perception of the appropriate french-to-english translation is better than yours.

Je ne pense pas que votre perception du français (qui est ma langue maternelle et paternelle ) ou celle de SeenItAll's est meilleure que la mienne.
Je ne suis peut-être pas un champion de l'orthographe ni sociétaire de l'académie française mais j'ai quand même quelques connaissances de la syntaxe ...

While the English document says, "the Captain attended the briefing between the two co-pilots" the original French is "le commandant de bord assiste au briefing entre les deux copilotes." The verb "assiste" in French translates better into "participates." Thus, a better interpretation is not just that the Captain was

Le verbe assiste .. ne se traduit certainement pas pour le contexte dans lequel il est employé .. comme le fait de participer

Si vous assistez a un briefing ou si vous assistez a un tournois de tennis .. vous ne prenez pas part au briefing ou au jeu ... vous êtes juste un spectateur
Le BEA (en français dans le texte) emploie le verbe "assiste"
Si le BEA voulais que l'on comprenne que le Cdt était part active de ce briefing .. il aurais du employer le verbe "participe"
Si c'était vraiment cela l'intention du BEA ... le rédacteur de cette note doit revoir sa syntaxe .. car il induit les lecteurs en erreur

La bonne formulation:
Le Cdt participe au briefing avec les deux pilotes

Salutations.

PS:
Translation in english on request

[EMIT]

Engine Anti Ice

Answer to # 1473

On the subject of Engine Anti Ice below -40, or not: you will get your answer if you read the Boeing Bulletin.
Engine Anti Ice heats the cowl inlet lip and the spinner bullet nose. In that way, it prevents the build up of large chunks of ice, that may break off and damage compressor blades further down the engine. To be used in regions of supercooled droplets.
Ice crystal icing takes place inside the compressor section of the engine, there where Engine Anti Ice does not heat anything. So, turning on TAI below -40 serves no purpose. Ice buildup on cowl lip or spinner does not occur, because the ice crystals bounce off them.

In general.
On the subject of pitot icing: yes, it can happen, on Airbus as well as Boeing.
TAT probe icing happens as well, probably more often than pitot icing. It can be observed from the TAT anomaly phenomenon (again, read the Boeing Bulletin). For crystal icing to occur, you do not have to fly through any solid wall of red, just the light green outskirts will suffice.

On the subject of stall recovery - even when not stalled, when ever is 15 degrees nose up an appropriate attitude at FL 350 in a big lumbering airliner?

[Chris733]

After flying quite a few pure glass cockpits there is something very comforting about getting a purely analogue aircraft......

[Turbine D]

EMIT,

A very nice summary of engine anti-ice usage. The only thing I would add is the warm air used for the nacelle and spinner cone anti-icing comes from bleed air off the compressor. So if you use it when it is not needed, it hurts the overall engine efficiency.

[TioPablo]

@GY

"From 2 h 10 min 05 , the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input."


So... What would be the correct input (in your eyes), given an undesired roll-right (nose-down), event?
You prolly are aware of the term "Heuristics" and its relationship to "intelligent" software design...

[lomapaseo]

A very nice summary of engine anti-ice usage. The only thing I would add is the warm air used for the nacelle and spinner cone anti-icing comes from bleed air off the compressor. So if you use it when it is not needed, it hurts the overall engine efficiency.

Since spinner cones has turned up twice in this thread, how the heck do you plumb on-off bleed air into a spinning cone on the front of an engine?

[FlamantRose]

French/English translation

Entirely in agreement with jcjeant.
Le verbe "assister" ne signifie aucunement que le Cdb prend part à la discussion. Il est présent et entend l'échange entre les deux co-pilotes mais ne "participe" pas à cet échange. Il n'y a aucun doute la-dessus. Il n'est nulle part fait mention que le Cdb ait dit quoi que ce soit à ce moment là sinon il aurait pris part et donc aurait participé.

As for the second phrase "tu peux éventuellement prendre un peu à gauche" cannot be translated as "you could go a little to the left". The french translation of "you could go a little to the left" is " tu pourrais aller un peu vers la gauche". And that does not meet the original french wording. The meaning of the "eventuality" is left out.

Cela fait partie des nuances de la langue française.

Amicalement

[RWA]

Interesting article which calls attention to the Trimmable Horizontal Stabiliser having remained virtually at full nose-up from very early on; calling attention to the fact that the same thing had happened before, to an A320 near Perpignan in November 2008:-

One question lies with the trimmable horizontal stabilizer (THS). The critical phase of the flight, from autopilot disengagement to the crash, lasted 4 minutes 23 seconds. During the last 3 minutes 30 seconds, the position of the THS went from 3 degrees to 13 degrees nose-up and then remained unchanged. Yet, from about 2 minutes before the crash, the pilot flying switched to pitch-down inputs.

So, as French website aerobuzz.fr pointed out, why did the THS stay in such a nose-up setting? This may hint at the flight control law being no longer “normal” but in a mode (“alternate” or “abnormal”) where the autotrim function is deactivated. In that instance, the crew has to trim the stabilizer manually. In an A320 accident that took place near Perpignan, France, in 2008, the crew’s failure to recognize this situation contributed to the catastrophic chain of events. In the case of AF447, the crew did mention “alternate law” in the recorded conversation.

History of Flight AF447 Puzzles Experts: AINonline

Also found an article on the Perpignan accident. This confirms that the investigators determined that "a progressive pitch-up deflection of the horizontal stabiliser as the A320 decelerated" had contributed to the accident.

The investigators concluded that water in the AoA sensors (which they thought had probably been introduced by sloppy maintenance on the ground) had frozen at altitude and caused the malfunction:-

"With the workload mounting in the cockpit, because the aircraft was on approach to Perpignan, the low-speed test commenced. But the blockage of the angle-of-attack sensors resulted in an underestimation of the limit speeds for the A320's angle-of-attack protection.

"The crew waited for the triggering of these protections while allowing the speed to fall to that of a stall," says the BEA. It says this "passive" wait for the protective systems, a lack of awareness of the risks, and confidence in the operation of the aircraft's systems "tend to show" that the captain and the ANZ pilot started the manoeuvre as a "demonstration of the functioning" of the angle-of-attack protection "rather than as a check"."

Although the stall warning sounded, and the captain increased thrust and pitched the aircraft nose-down, the configuration of the aircraft - notably a progressive pitch-up deflection of the horizontal stabiliser as the A320 decelerated - and the failure to understand the jet's behaviour, resulted in the situation deteriorating and the crew's losing control of the stall recovery. All seven occupants were killed when the A320 struck the water, just 62s after the stall alarm.

Sensor icing caught out A320 crew in Perpignan crash

[Mike-Bracknell]

Forgive me for being an occasional 'dipper' into this thread (no time to read it and the others to completion) but has anyone overlaid the ACARS messages onto the BEA transcript yet to possibly point out what the aircraft thought it was doing whilst those in the cockpit were clueless?

[cwatters]

I'm not a jet pilot or engineer but..

Has the possibility of a fault with the PF stick been ruled out? Suppose that fault added a constant nose up. Presumably that would cause the THS trim to exagerate the problem? A stuck bit fault in a digital system can appear to add a constant to an otherwise correct value (eg it adds 1,2,4,8,16 etc) but you would hope error detection catches such faults.

Anyway Google finds..

Chapter 5. Flight controls

Airbus A320 Family Non-Normal Notes

5.19. Sidestick unannunciated transducer faults

It is possible for a failed sidestick transducer to cause uncommanded control inputs. If no fault is detected, the result is that the aircraft behaves as if that input had actually been made. Generally, the autopilot will disconnect and any attempt to control the aircraft with the failed sidestick will fail. The aircraft should be recovered with the other sidestick using the takeover button. Keeping this button pressed for 40 seconds will lock out the failed sidestick, and the autopilot can then be re-engaged. The autopilot should not be disconnected in the normal manner as pressing the takeover button will re-introduce the failed sidestick and the uncommanded input; use the FCU instead.

[wiggy]

Mike-B

whilst those in the cockpit were clueless?

I was going to say "ouch" but on second thoughts I take it you mean "clueless as to what it was doing"?

[NigelOnDraft]

This aircraft went down 3.5 minutes after the AP disengaged and handed control to the PF, without apparently giving any indication to the PF as to why the AP disengaged.

A supposedly highly sophisticated aircraft automation system just gives up in a flight situation which it cannot handle and gives control to the humans on the flight deck without any indication as to why it did this? WTF!

Is there an SOP for the pilots to deal with this situation?

If so, can the SOP be effectively executed in less than 3.5 minutes (or before the aircraft falls out of the sky) and if not, why not?

These questions really bother me.

There is an SOP - it is quite simple:
PF flies aircraft and states I have Control.

It can, and should, be 'effectively executed' in <5 seconds. Priority #1 is flying (and Airbus philosophy) and far above discussion, let alone diagnosis, of "why" the AP disconnected. The reasons it can do so are numerous - and largely irrelevant at the time.

A supposedly highly sophisticated aircraft automation system just gives up in a flight situation which it cannot handle and gives control to the humans on the flight deck without any indication as to why it did this? WTF!

A somewhat strange way of thinking Even in an Airbus, at no point (that I can think of) is the aircraft AP system considered "more capable" by itself, without monitoring, than the Flt Crew. At no point are the crew absolved from monitoring the AP, and in the event they are not content with what it is doing disconnecting the AP and flying manually (albeit it may require a change in profile e.g. to a GA from a couple approach / autoland). In the same vein, the AP system is designed to disconnect itself (and warn the crew) as soon as it is "overloaded" / "confused" / being pushed outside it's "comfort zone"...

[Basil]

Pointed out to me by a private aviation group, interesting comment here.
Credit AVweb.

AVmail: June 6, 2011

Letter of the Week: Airbuses Fly "Like a Video Game"

I would like to offer my comments and perspective with regard to the Air France Flight 447 accident. I have been a A-330 captain since 2003 and have over 4500 hours in the aircraft. While many A-320 pilots undoubtedly have more series time, I believe this probably makes me one of the most experienced A330 pilots in the world.

When asked how I like the aircraft, I tell people that there is likely no easier airplane to take over an ocean, and that the systems design and presentation is superb. That said, the automation is more complex and less intuitive than necessary, and the pilot-aircraft interface is unlike that of a conventional aircraft. Most important with regard to this accident is the fly-by-wire sidestick control. The sidestick itself has a very limited range of motion, making inadvertent over-control very easy. Of even greater significance, the stick itself provides no "feel" feedback to the pilot. That is, unlike a conventional aircraft, the pilot does not get a sense through pressure of how much input is being sent to the control surfaces. The most important advice I give to pilots new to the Airbus is to treat the aircraft not as an airplane, but as a video game. If you wait for the sidestick to tell you what you are doing, you will never get an answer.

Taking into consideration that Air France 447 was at FL 350 (where the safe speed envelope is relatively narrow), that they were in the weather at night with no visible horizon, and that they were likely experiencing at least moderate turbulence, it does not surprise me in the least that the pilots lost control of the aircraft shortly after the autopilot and autothrust disconnected.

Let's keep in mind that these are not ideal conditions for maintaining controlled flight manually, especially when faced with a sudden onslaught of warning messages, loss of autofllght, confusing airspeed indications, and reversion to "alternate law" flight control, in which certain flight envelope protections are lost.

A very bad Airbus design feature is thrust levers that do not move while in autothrust. They are instead set in a detent which would equal climb trust in manual mode. If the pilots did not reset the thrust levers to equal the last cruise power setting, they likely eventually ended up in climb power, making it difficult to reset the proper cruise power setting and adding to what was likely already a great deal of confusion.

But the real problem probably occurred immediately after the pilot flying grabbed the sidestick and took over manually. Unfortunately, airline pilots rarely practice hand-flying at high altitude, and almost never do so without autothrust engaged. As a result, we forget that the aircraft is very sensitive to control inputs at high altitude, and overcontrol is the usual result. Because the Airbus sidestick provides no feedback "feel" to the pilot, this problem is dramatically compounded in this aircraft.

I believe the Air France pilot grabbed the sidestick, made an immediate input (because as pilots, that's what we tend to do), and quickly became quite confused as to what the aircraft was truly doing. This confusion likely was exacerbated by fixating on airspeed indications that made no sense while trying to find a power setting with no airspeed guidance.

When transitioning from autopilot to manual control at altitude in the Airbus, the most important thing to do at first is nothing. Don't move a thing, and then when you do, gently take hold of the sidestick and make very small inputs, concentrating on the flight director (which, in altitude hold, should still have been providing good guidance). Of course, this is much easier said than done with bells and whistles going off all over the place, moderate turbulence and a bunch of thunderstorms in the area. As I said before, treat it like a video game.

So why did the Air France pilot find himself at the limits of sidestick travel, and then just stay there, maintaining a control input that simply could not logically be correct? When things go really bad and we are under intense pressure, it is human nature to revert to what we know from previous experience. Remember, the Airbus flies like no other aircraft in that the sidestick provides no feedback to the pilot. It is a video game, not an airplane.

I believe the Air France pilot unintentionally fell back on all of his previous flying experience, in which aircraft controls "talkedF" to him when he moved them. Distracted by many confusing inputs, he instinctively expected to be able to control the aircraft by "feel" while dividing his attention to address other matters. I've seen it happen in the simulator, and in an Airbus this is a sure way to lose control of the aircraft and is possibly the most dangerous aspect of Airbus design philosophy.

One last note: Airbus pilots often claim that the aircraft "can not be stalled." When the flight controls are in "normal law" this is a reasonably true statement. However, in "alternate law," as was the case here, stall protection can be lost. If we ever practiced this in the simulator, I don't remember it.

Lest anyone think I am blaming the Air France pilots for this accident, let me be clear. Despite all of my experience in the aircraft, I am not the least bit certain that I would have been able to maintain control under the same circumstances. I do feel certain that were you to spring this scenario on pilots in a simulator without warning less than half of them would have a successful outcome. Safely flying the 320, 330 and 340-series Airbus requires something of a non-pilot mindset.

Name Withheld

Editor's Note:

We have spoken with the writer of this letter to confirm his identity and honored his request for anonymity.

[HundredPercentPlease]

Originally Posted by Carjocky

A supposedly highly sophisticated aircraft automation system just gives up in a flight situation which it cannot handle and gives control to the humans on the flight deck without any indication as to why it did this? WTF!

Carjocky, you are evidently not a pilot. But I will answer your concerns in case any other non pilots or journalists think your comments carry any credence.

Any autopilot/autothrust system needs inputs to work. If one of more of the required inputs are lost, it will stop working.

When the autopilot dropped out here it was clear to the pilots why it had dropped out, and it told them what control law they were now in. The PF verbalised the control law, and the reason for the autopilot dropout.

Flying without an autopilot is not a problem. Flying with unreliable airspeed is not a problem, and there is a QRH procedure to help you climb or descend, fly level and fly an approach. It doesn't take any time to "do" this procedure, since the first action for UAS in level flight is to do nothing - ie maintain the cruise pitch and thrust using manual controls. Unfortunately here the pilots for some reason (much debated and not yet understood) increased the pitch and stalled the aircraft. The exact details of the effect and strength of the turbulence is not yet known.

They then had to unstall the aircraft, with UAS. This, again, they failed to do as they did not reduce the pitch.

From the scanty information from the BEA, the only "surprise" from the aircraft was the lack of stall warning at very low speed. It might have been better if it was not suppressed, but to any pilot with more that 10 hours experience it should have been obvious that they were stalled. Quite why they did not see and correct the stall has yet to be explained - but there may well be more clues in the full report.

[Level100]

Chers
Flamant Rose et jcjeant,

I still am in disagreement with you:

Entirely in agreement with jcjeant.
Le verbe "assister" ne signifie aucunement que le Cdb prend part à la discussion. Il est présent et entend l'échange entre les deux co-pilotes mais ne "participe" pas à cet échange. Il n'y a aucun doute la-dessus. Il n'est nulle part fait mention que le Cdb ait dit quoi que ce soit à ce moment là sinon il aurait pris part et donc aurait participé

.

Really, "assister" is not always employed in the restricted use you advocate. While I can agree with you for the assistance to a tennis-match, I do not definetely would agree for the assistance to a briefing.
That at least others have the same feeling like me (note my careful, polite and non-authoritive wordings in my initial post), I might be allowed to substantiate by showing an exerpt from the very first google answer to the meaning of "assister" and its translation :

assister, verbe transitif
Sens 1 Secourir, aider quelqu'un. Synonyme secourir Anglais to assist Sens 2 Seconder. Synonyme seconder Anglais to assist Sens 3 Être présent. Ex Assister à un match de tennis. Synonyme être Anglais to attend
Note that the meaning that you state as exclusive (il n'y a aucun doute) even ranks only 3rd place.
Now, I also have looked in some old dictionaries (50 y), and, curiously enough, the
order is the other way around.

Given these facts we possibly could agree on the following
1) assister is a word for which the extent of its meanings has some leeway
2) this leeway apparently seems to change in time
3) most likeky the BEA-writer was not conscious about all this semantic issues this when he used the expression
4) and anyhow we do not know his own perceiption of our subject of discussion.

Bien Amicalement

[jcjeant]

Hi,

Given these facts we possibly could agree on the following
1) assister is a word for which the extent of its meanings has some leeway
2) this leeway apparently seems to change in time
3) most likeky the BEA-writer was not conscious about all this semantic issues this when he used the expression
4) and anyhow we do not know his own perceiption of our subject of discussion.

Bien Amicalement

My last answer about this syntax thingh
The verb "assister" can indeed be understand .. have the meaning of help someone or the meaning of rescue someone .. etc ...
But as used in the stance of the BEA .. the meaning is the same than "assister a un tournois de tennis"
You can't help a "thing"
Briefing is a "thing"
Vous assistez a une chose .. a un spectacle .. a un évènement
Vous ne pouvez pas aider une chose .. un spectacle .. un évènement
Mais vous pouvez aider .. assister .. secourir une personne .. un animal
C'est juste une question de syntaxe .. le contexte dans lequel le verbe est employé
It's no in the BEA stance two ways meaning ... it's only one .. and it's "attend"
The BEA don't use the verb "assist"

3) most likeky the BEA-writer was not conscious about all this semantic issues this when he used the expression

Indeed and let me wonder if the mother language of BEA french note writer is the french language .... as it's a gross syntax mistake (if his meaning was to write that the captain was there to give assistance to the two pilots at the briefing)