AF 447 Thread No. 8

[gums]

THNX Retired for discussing how easy using an AoA indication is.

Sucker shows stall or optimum approach speed or.... regardless of your weight. And we can still use rules-of-thumb to make a comparison - you know, 175 knots plus 5 knots for every thousand pounds above 3,000 ( F-101B VooDoo). If the AoA is really high or low at the textbook speed, check your flaps or fuel gauge or... And that's the OODA I was referring to, PJ, basic instrument crosscheck.

I am having my leading edge flap failure approach digitized, and will make it available in a few days. I flew airspeed and not AoA due to controllability factors, but you can see the AoA bracket and watch what it does just before touchdown. Can also see how valuable the flight path marker is, as it shows you where you are gonna crash.

[PJ2]

Hi gums;

Re, "THNX, Retired for discussing how easy using an AoA indication is.

Sucker shows stall or optimum approach speed or.... regardless of your weight. And we can still use rules-of-thumb to make a comparison - you know, 175 knots plus 5 knots for every thousand pounds above 3,000 ( F-101B VooDoo). If the AoA is really high or low at the textbook speed, check your flaps or fuel gauge or... And that's the OODA I was referring to, PJ, basic instrument crosscheck. "

Thanks - I learned something again...OODA. We have a slightly different approach but I believe the outcome is the same. Thanks for bringing it up.

I have a question regarding an AoA indicator and how airline crews would use it.

With reference to the following, from the BEA Interim Report #2, pg46, it states:

In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold. In clean confi guration, this threshold depends, in particular, on the Mach value in such a way that it decreases when the Mach increases. It is the highest of the valid Mach values that is used to determine the threshold. If none of the three Mach values is valid, a Mach value close to zero is used. For example, it is of the order of 10° at Mach 0.3 and of 4° at Mach 0.8.My question is, how does one use the guage in operations, and how does one stay away from the stall AoA using an AoA guage when the AoA at which the aircraft will stall changes with Mach? Would the guage be calibrated, (using much the same logic as the ECAM does in Alt/Dir Law - a table was posted around Thread 4 or 5 showing this AoA calculation at which the stall warning would sound).

I'm not arguing against installing/using an AoA guage here. I frequently interrogated the ACARS function to watch the flight data which included the AoA among many other interesting parameters.

But, if I may, I think that there is more to an AoA guage than just installing and selectively watching it. Clearly, the AoA at which a transport will stall at high Mach number at cruise altitude is different (due Mach effect) than an approach AoA which is typically 8 to 12deg depending. In cruise, a stall AoA may be as low as 4deg, as it was here when the first blip of the stall warning was heard, and later, at a much-reduced Mach but at FL376 or so, the aircraft was starting to stall at an AoA of around 7deg. I'm trying here to imagine how the guage would get the crew/PF of AF447 out of trouble and how the PF would use an AoA indication and what AoA he would be targeting.

[HazelNuts39]

Quote HN39: I'm aware that the 'low speed awareness' markings are fundamentally different from Airbus' markings of 'characteristic speeds'.
Quote Clandestino: Not valid for all Airbus characteristic speeds. Valpha max and Wsw on Airbus are very similar to low speed cue. ADC/IR design, flight controls and display architecture are different yet displayed information is similar.

Reply: AFAIK Valpha max is the '1g' stall speed and is not g-sensitive. It is not displayed in alternate law. Although Vsw is g-sensitive, it is calculated for the current weight and moves off-scale as the speed tape moves up to display 60 kts. As I understand low speed awareness (see here (http://www.pprune.org/tech-log/484457-aoa-asi-low-speed-awareness-2.html#post7174619)), and you concurred in your post 467, it would maintain the 'Vsw' where it is on the display, while the speed tape moves.
Quote Clandestino in post#467: I strongly suspect your further line of thought, about showing wrong stall warning speed when IAS gets unreliable is correct ...
Quote FCOM 3.04.27 p.7: (Alternate Law) ValphaMax disappears ... Unlike VLS, which is stable, VSW (stall warning speed) is g sensitive so as to give additional margin in turns.

Quote HN39: But when airspeed has 'gone south' and in Alternate Law, may be the 'low speed awareness' is better?
Quote Clandestino: If airspeed is lost, how could we have possibly have low speed awareness? High alpha awareness is even better and is provided through aural stall warning.

Reply: The aural stall warning comes 'out of the blue' for the pilots, they do not see it coming, consider it 'inappropriate' and dismiss it as 'false'.

Quote HN39: It would have informed the pilots of the 'validity' of the first brief stall warnings, that they were transient and no reason for concern at that time
Quote Clandestino: At the cruise Mach, they were not 'valid', they were valid. They were transient as the aeroplane was jerked into climb at its max recommended cruise level and were reason to be very, very concerned.

Reply: Yes, they were valid, but partly due to turbulence, and therefore transient, and as such, not calling for immediate nose-down response.

[RetiredF4]

OC
Retired F4
I see what you mean now - I was thinking of a different definition of expectation pattern. That you have a certain desire and when you move the controls you think that the aircraft will respond to your expectation no matter what the reality is.



No, you still dont get it. You have an intention to change the flightpath a given amount, you move the controls and expect the aircraft to respond to the flight control input in relation to the flight control change. The reality of the response shows on the instuments, or you can see and feel it if flying visual and you compare it to the expected outcome and use that one again to fine tune your input. It´s a closed loop system.

OC .... no matter what reality is..... is totally off the scope, don´t know where you can find it in my post.


If the input is not done by yourself or cannot be observed (SS issue), you dont know what to expect,´you have no reference, only the real response to an unknown input / unknown malfunction / unknown external input can be observed on the instruments. The source of the unwanted deviation of the desired outcome is not known, only the result. Therfore the correction input to the situation might not be appropriate to the situation as i described extensively in my prior post.

Back to the SS, it could be that PF is already correcting an undesired pitch attitude by SS input, and PNF might add his own input, as he doesn´t know that a correct input is already being made by the PF.

Nearly all performance issues can be observed and judged by instruments to the "what" and "why" is it happening, but as told before, it gets tricky with flight path issues. Those can be (and normally are, but not exclusively) SS or yoke induced. The yoke can give feedback to the PNF in relation to the kind of input, the amount of input, the agressiveness of the input and the duration of the input, the SS in the present configuration dosn´t.

Enough for now.

[RetiredF4]

PJ2
My question is, how does one use the guage in operations, and how does one stay away from the stall AoA using an AoA guage when the AoA at which the aircraft will stall changes with Mach? Would the guage be calibrated, (using much the same logic as the ECAM does in Alt/Dir Law - a table was posted around Thread 4 or 5 showing this AoA calculation at which the stall warning would sound).

Our gauge was a simple round one (posted it before) with aditional tone and indexer lights in the front window for the approach and landing. I don´t know (but assume) that it was somehow calibrated. We could use it over the complete speed range from 0 to Mach 2.2 in all altitudes and under all loads and in all configurations. As our Rhino was not digital and had only an limited capable flight data computer i assume, that it is no rocket science today either to make it usable under all circumstances. With power on the aircraft and the WOW switch pressed by mintenance we hand tested it by turning the vane and observing the gauge, lights and tone at the appropriate units of AOA (don´t know even if the indicated units were equal to degrees).


PJ2
But, if I may, I think that there is more to an AoA guage than just installing and selectively watching it. Clearly, the AoA at which a transport will stall at high Mach number at cruise altitude is different (due Mach effect) than an approach AoA which is typically 8 to 12deg depending. In cruise, a stall AoA may be as low as 4deg, as it was here when the first blip of the stall warning was heard, and later, at a much-reduced Mach but at FL376 or so, the aircraft was starting to stall at an AoA of around 7deg.

Good points, but again, i think it is a calibration kind of thing and for sure relevant to the Rhino and other fighters as well. The indicated units could be calibrated to the facts you mentioned and then the numbers would be identical to all situations from T/O to Landing.

PJ2
I'm trying here to imagine how the guage would get the crew/PF of AF447 out of trouble and how the PF would use an AoA indication and what AoA he would be targeting.

First it should keep them out of trouble. There is a fast familirization with the values normal present during cruise (normally close to max range) approach and landing. In a situation where these values start to deviate from the known common values it indcates not only a state, but also a trend. Now you may say, that the speed tape does the same, wether you get fast or slow. The difference being that the AOA and consequently also an AOA indication also puts the loading of the airframe into the equation. During the initial pullup the AOA would have increased from known value to the stall threshold value thus telling the PF to ease of on the controls , reduce pitch and never let this AOA go higher than safe value. While the Stall warning is only an ON / Off indication, the reference to the AOA is a "performance state" indication with hints to the momentary trend. Changes due to loading or unloading are immidiately observable. That could have helped after stall had occurred during the recovery attempts as well. SS aft, AOA stays high, SS forward, AOA reduces, keep SS longer forward, AOA reduces further.... and so on. Even the effects of the power changes would have been seen on the gauge, thus developing a quick learning pattern what will work and what is wrong.

In all my time in the AF i never had or even heard from an AOA malfunction (except birdstrike) and understanding and working with the gauge, the aural tone and the indexer lights was no issue at all.

Just adapt it to the use in the individual airframe and go for it.

[HazelNuts39]

My question is, how does one use the guage in operations, and how does one stay away from the stall AoA using an AoA guage when the AoA at which the aircraft will stall changes with Mach? One could argue that, even without indication of stall and SW AoA's, having an indication of actual AoA is better than nothing. Does anybody know if and how the BUSS addresses that problem?

P.S.
AFAIK the BUSS indication of SW and Stall AoA does not change with Mach. Is is a function of flap/slat configuration only. The stall warning AoA with all three ADR's off is 8.6 degrees in F/S configuration 0/0 . Above FL 250 the pilots are instructed to fly pitch and power and not use the BUSS.

[DozyWannabe]

PJ2, I loved the early 737's and 727's but didn't want the automation of the Airbus so stayed away from it. Only because it took a lot of your control away and let automation take over.

When pilots cannot control an airplane because automation is doing something they don't understand I don't like it. Maybe I am too old and don't understand the new technology but I love the feeling of being in control no matter what the computer thinks. My 757 let me do all of that.

We need to be careful here. The automation on the A320 and her widebody sisters is in fact not a great deal more advanced or restrictive than that in your 757, and never was. The difference was that in the 757 the safe limits were coded into the autopilot, whereas on the A320 those same limits were handled by the protections in the FBW logic.

It's very important to separate the automation concepts from the FBW concepts in order to understand them properly. There is some crossover in the case of the protections and autopilot limitations, but it stops there. What I think you're talking about (and correct me if I'm wrong) are the "what's it doing now?" incidents that came with automation - and they were as prevalent on the 757 and 767 as they ever were on the Airbus FBW types. Yes, you can turn it all off on the 757 - but you can turn the automation off on the A320 too.

As I said earlier, there was a greater leap in automation between the 727 and 757 than there was between the 757 and the A320.

If you're talking about the A320's protections - which only go away if there's a significant systems failure - then that's a very distinct aspect of FBW which has nothing to do with automation, and in any case you only encounter them if you try to do something dangerous. Otherwise, as PJ2 and others have testified, the A320 and her sisters hand-fly beautifully. It's not taking control away from you so much as helping you maneouvre safely within the limits of the airframe.

Also a side stick with a single pilot plane would be just fine.

Looks like it works just fine on a two-crew plane as well, going on the evidence - even with yokes, only one of those two pilots should ever be controlling the aircraft, after all. The sidesticks were nothing to do with automation, they were an outgrowth of the fact that big, heavy yokes weren't necessary on fully-hydraulic airliners, and even less necessary with FBW.

I realise that psychologically a connection could be made between the transition from big, heavy yokes to the lighter and less-obtrusive sidestick and the belief that pilots were relinquishing more control to automation, but as I've said above it just isn't the case. FBW/protections and FMS/automation are two very separate and distinct things, and it's important to bear that in mind.

[Old Carthusian]

Retired F4
Yes I do get it but we were defining expectation pattern differently - we were both focusing on different things. However, we are not talking about visual flying but instrument flying at night with no visual cues. What do you do then? You rely on the instruments to tell you what the aircraft is doing. In fact it's the only thing you can do - relying on any other cue is a recipe for disaster. Your argument becomes irrelevant because the cues or measures you need for visual judgement do not exist. Other sensory judgement is also worthless. You need a a measure. You have to rely on your instruments. A visual appreciation is totally worthless in this sort of situaiton. Hence being able to see the position of the control medium means nothing. Reference to the instruments and what they tell you is what matters.

[Owain Glyndwr]

Retired F4

OK, I see how an AoA gauge works - it doesn't need any calibration to tell you what the AoA is; it's not until you want it to tell you how close you are to stall that calibration comes into play.

Now AFAIK, you can't do that with any precision unless you know Mach number, since stall AoA is Mach dependent, so my question is how did your F4 AoA gauge work in a UAS situation?

BTW, I'm not trying to argue against fitting AoA gauges, just trying to establish their capabilities.

[RetiredF4]

OC
Retired F4
Yes I do get it but we were defining expectation pattern differently - we were both focusing on different things. However, we are not talking about visual flying but instrument flying at night with no visual cues. What do you do then? You rely on the instruments to tell you what the aircraft is doing. In fact it's the only thing you can do - relying on any other cue is a recipe for disaster.

Well, last try. It works both ways, also in IMC and dark night and especially there. Your words, ....."You rely on the instruments to tell you what the aircraft is doing"..... and i fully agree and never ever said anything else. But flying does not stop there. A pilot will be and has to be in constant monitoring modus to compare the "what is the aircraft doing" to the "what should the aircraft be doing, which i call the expectation state. To be able to get this comparison you need the input value into the system . If you are flying manual in your 152 and you didn´t deflect any flight controls, because you didn´t want any change of the flightpath, but you observe a sudden bank, you know it is not your input, because you have your hands on the yoke and didn´t move any control surface. There must be another reason causing the input and that again might cause a diferent action from yourself.

Same if you are flying as PF, wether you made the flightcontrols change by manual input or by programming the automatics, you will know that it was your input. Will the PNF know ? He observes the change on the instruments and in a yoke aircraft observes the yoke movement in his lap, but in a non interconected SS aircraft? He has to guess.

Well, that works most of the time, because transport aircraft are and should be operated in a safe and preplanned mannor, so due to CRM it is common knowledge when something should happen in regard to flightpath or performance parameters change, because it is announced by PF, briefed before, or ordered by ATC. Therefore the expectation (we will now start descent, climb, turn..... ) shows as reality on the instruments.

When the sh**t hits the fan really bad like in AF447, the reality on the instruments is no longer nearing the expectation, the aircraft does not behave like expected (i´m in TOGA hehe..........I pulled back for quite a while....) and even both PF and PNF have now different understandig of things and the awareness, what the other guy is doing is lost. The corelation of the aircraft behaviour to the flight control inputs is lost, no valid feedback loop any more and therefore complete loss of situational awareness.

By the way, as far as i understand FBW systems it would be the same. If the system would loose the ability to recognize and measure its own input into the system, it would not be able to maintain normal control, like the dampers then counteracting the flightcontrol deflections.

[RetiredF4]

Owain Glyndwr
Now AFAIK, you can't do that with any precision unless you know Mach number, since stall AoA is Mach dependent, so my question is how did your F4 AoA gauge work in a UAS situation?

I dont know, how it was done, what input it used. Im no techician´and also technically very interested i never questioned the functioning of the AOA. It was there, it was always working, also with a iced up pitot tube (we only had one).

I don´t see the problem there, the information was present in the AF447 aircraft (Stall warning, FDR traces....), it was not displayed.

[DozyWannabe]

...but in a non interconected SS aircraft? He has to guess.

Or, y'know, ask.

("Are you pulling up?"
"Yes. Shouldn't I be?"
"No - we're approaching stall - I have control."
"You have control.")

An exchange for which there was plenty of time between disconnect and apogee/stall. Remember a similar lack of communication did for Birgenair, despite the yoke being in the PNF's lap and - eventually - stick shaker going off.

[RetiredF4]

DW
Or, y'know, ask.

("Are you pulling up?"
"Yes. Shouldn't I be?"
"No - we're approaching stall - I have control."
"You have control.")

An exchange for which there was plenty of time between disconnect and apogee/stall.

Why shold he ask? What would have triggered him? Why should one assume, that the PF is applying backstick in a situation, where it is not appropriate? Even the aircraft talked different to him after the initial pull. From 02:10:29 until 02:10:45 and from 0211:05 until 02:12:00 the loading was below 1g, thats more than 1 minute less than one g against 26 seconds with g at max 1.15. The instruments should have triggered him, absolutely correct. But he didn´t get the clue, otherwise he would have asked or even he would have taken over the aircraft like you mentioned, correct? Maybe he was thinking some kind of updraft, some kind of misreading altitude (speed was gone, why shouldn´t VS and altitude not be affected)? Maybe the unloading gave him the impression, that PF is doing the right thing.

We don´t know what he was thinking, what he was "guessing". But he couldn´t see the SS input and he didn´t ask, and he didn´t get to the right decision, that one we do know.

[Old Carthusian]

Actually no - as a pilot you should be reading your instruments and taking your cue from them. You might have expectations but these need to be sublimated to the readings on your instruments. They will tell you what is happening. You seem to be describing an expectation state exactly the same as I interpret the phrase and this is dangerous. By allowing yourself to accept this state and to let it influence your actions you are running the risk of deviating from actuallity and ignoring the warning signs. Your definition of expectation is also flawed - it is a belief that a future situation will pertain or a future flow will occur. It is not per se linked to reality. Reality is what happens and rather than focus on expectations one should be focusing on things as they are and trying to predict what will happen based on the reality. Once one gets into expectations one can wander off the path to a very large degree.

[RetiredF4]

OC
Actually no - as a pilot you should be reading your instruments and taking your cue from them. You might have expectations but these need to be sublimated to the readings on your instruments. They will tell you what is happening. You seem to be describing an expectation state exactly the same as I interpret the phrase and this is dangerous. By allowing yourself to accept this state and to let it influence your actions you are running the risk of deviating from actuallity and ignoring the warning signs. Your definition of expectation is also flawed - it is a belief that a future situation will pertain or a future flow will occur. It is not per se linked to reality. Reality is what happens and rather than focus on expectations one should be focusing on things as they are and trying to predict what will happen based on the reality. Once one gets into expectations one can wander off the path to a very large degree.


I´m glad, i survived 20 years of flying high performance fighter aircraft and the students who learned flying with my help still are all alive.

[jcjeant]

In 2008, Airbus recommended replacement of the Thales pitots with Goodrich pitots which had less susceptibility of failure due to icing or heavy rain conditionsA recommendation is not binding
If you refer to motorists not to exceed 120 Km / h on a highway .. what result?
If you ban motorists from exceeding 120 Km / h on a highway .. this is different (constraint) and the results will not be the same

[Owain Glyndwr]

Retired F4



I dont know, how it was done, what input it used. Im no techician´and also technically very interested i never questioned the functioning of the AOA. It was there, it was always working, also with a iced up pitot tube (we only had one).

I don´t see the problem there, the information was present in the AF447 aircraft (Stall warning, FDR traces....), it was not displayed.

OK, since I posted my query I’ve found an example of an F4 operational manual on the ‘net.
Short answer is that it wasn’t done with any precision.
The AoA probe doesn’t give incidence in degrees, but an AoA ‘index’. Probe output goes from 0 to 30 arbitrary units for an AoA range of -10 to +40. UAS pages give stall at 27 units, stall warning (pedal shaker) at 21.3~22.3 depending on aileron droop. . There is no mention of any variation of stall or stall warning with Mach number. Values of AoA units are suggested for a range of flight cases, but so far as I can see these simply replace pitch by AoA units as memory items. The weight range for the F4 seems to be small enough for such a simple approach to work. For example the index for approach (19 units) is said to be “adequate” for all loadings and in fact is a simple reflection of approach at 1.3Vs or whatever being close to a unique AoA for all CGs. But the indicated AoA is only valid with gear down – with gear up the aircraft stalls 3 or 4 units earlier. Stall, it is said, is preceded by buffet starting at 12~14 units and stall will “usually be above 25 units” although the actual angle varies considerably with loading. With flaps and gear down the pedal shaker operates about 17 kts above stall and 9 kts before wing rock.


[B]I haven’t found any mention of automatic indication of stall AoA, so presumably you had to set one or more of the ‘bugs’ appropriate to the flight state?


Overall, I have to say that my impression is one of a system that can be made to work well enough on an aircraft operated as military, but which would need some additional sophistication to meet the needs of civil operation, unless one accepts use of memory items for typical AoA in routine day to day operation. Nothing wrong in that, it is already used in pitch, and any indication of AoA would be better than none, but I don’t see it as an all embracing panacea I’m afraid.

[gums]

I go with Retired about the useful AoA at all mach numbers.

For example, the infamous "pitch up" in the VooDoo had plenty of warning when subsonic, lile medium buffet and wing rock. But we had zero warning when supersonic. So our AoA doofer must have corrected for the change in mach, as it worked like a charm to keep us outta trouble. We flew around with a "limiter" on that keep you from getting within "x" degrees of the stall AoA ( called MCSL). If we pulled thru it ( 60 pounds or so), then the "pusher" moved the stick forward ( 28 more pounds to overcome if you were determined to get out of control).

The AoA steam gauge was large and had the "barber pole" to show the stall AoA and existing AoA.

Viper was the same as far as working supersonic, but we didn't get the AoA bracket until gear was down ( no steam gauge).

I have no problem with relying on the gauges when IFR, as body sensors are no good. Ask Retired about flying formation at night. After a few turns in the WX you were convinced that the flight leader was inverted or had done a roll, heh heh. So a quick glance back inside really helped.

[PJ2]

RetiredF4;
Quote:
PJ2
I'm trying here to imagine how the guage would get the crew/PF of AF447 out of trouble and how the PF would use an AoA indication and what AoA he would be targeting.
First it should keep them out of trouble. Thank you for your extended response and for indulging my question. I understand that the technical details aren't at hand...no problem R.F4.

My question isn't about how the guage is read, but what assumptions lie behind its design and whether such assumptions are known and understood by flight crews.

Does such an indication take into account the effect of high Mach Number on the stall AoA?

If not, such a guage or indication is useless for determining when/if an aircraft in cruise at high Mach Number has reached the stall AoA.

If the AoA indication adjusts for high Mach Number, (as the ECAM stall warning does when the Airbus is in Alternate Law), then the indication is useful.

That's all I meant.

Here is the ECAM logic which triggers the stall warning from AoA in Alternate Law - this was posted earlier, (can't recall who to credit), but it may illustrate what is meant by the question:

http://www.smugmug.com/photos/i-Qr5xMMw/0/X3/i-Qr5xMMw-X3.jpg

[DozyWannabe]

Why shold he ask? What would have triggered him? Why should one assume, that the PF is applying backstick in a situation, where it is not appropriate?

For starters because the aircraft has started to climb, and vertical speed has increased from +1500fpm to +4-5000fpm in a matter of seconds. They had discussed altitude and decided not to go any higher than the level they were at because of the weather. Autopilot is off - who else could be causing the climb?

You ask because communication is a tool that's given to you before you can even pronounce the word "aeroplane". Even if you've got a yoke in front of you, unless you're in a life-and-death situation (which this wasn't at that point), you should take it gently, follow through and verbally confirm what you're feeling before you try to take over. I've never heard of a successful recovery requiring handing over of control where one pilot simply grabbed the controls from the other - except in instances where the other pilot was clearly incapacitated.

But he didn´t get the clue, otherwise he would have asked or even he would have taken over the aircraft like you mentioned, correct?

He did try to correct the PF verbally, so it's reasonable to assume he realised, or at least felt that something was wrong. I'm not an expert, but his speech pattern seems to indicate indecision. The captain has put the PF in charge - if the PNF takes over before the captain arrives, will it reflect badly on him if it turns out to be unnecessary? Perhaps he felt that correcting the PF verbally until the captain arrived would be the safest path to take

Maybe he was thinking some kind of updraft, some kind of misreading altitude (speed was gone, why shouldn´t VS and altitude not be affected)?

Well, for a start I don't think there's an updraft in existence that could cause a heavy widebody to climb like that, plus an updraft wouldn't necessarily cause the pitch to increase.

If he knew his systems then he'd be aware that altitude and VS rely on a completely different set of sensors (static ports) than airspeed (pitot tubes), and it was unlikely both would have been affected.

Maybe the unloading gave him the impression, that PF is doing the right thing.

I don't think G-loading is as integral to the scan in an airliner is it is in a fighter. It'd definitely be secondary to ADI, altimeter, VS and airspeed.

We don´t know what he was thinking, what he was "guessing". But he couldn´t see the SS input and he didn´t ask, and he didn´t get to the right decision, that one we do know.

We also know, as I said above, that he tried to correct the PF verbally several times before the Captain arrived - he clearly didn't think things were going well. The next logical step would have been to take control, and he did try just before the Captain arrived, but didn't follow through - and the PF took back control unannounced a few seconds later

@jcj - The Airbus Service Bulletin was binding in terms of the work being *required*, not recommended - and the work having to be done by a given date. An Airworthiness Directive is the next level up where the type is effectively grounded until the work is done, and that wasn't really necessary in this case. ADs are only used when a fault is so severe that it is likely to result in the loss of the aircraft every time it occurs. The successful recoveries that pre-dated AF447 prove that this was not the case.

[jcjeant]

The successful recoveries that pre-dated AF447 prove that this was not the case. I don't consider this as a valuable argument
In the case of the Concorde .. predated problems with tires happened and none produced a fire ..
And one day .. same problem .. and fire .. and end of flight at Gonesse (it's not a airport ... unfortunately)

[DozyWannabe]

@jcj:

What you think is not the issue here. I repeat - an AD is only necessary when a fault is severe enough to be likely to cause the loss of the aircraft every time it occurs - for example, the DC-10 cargo door failure leading to hydraulic failure.

If ADs were required in every case where a fault made it possible to lose the aircraft then a lot of the world's fleets would spend a lot of the time grounded.

For example, if you go back to the late 1990s, the 737 fleet was flying around with a known problem in the rudder PCU, they just did not know what that fault was at that stage. The NTSB were considering pushing the FAA and international authorities AD to ground the 737, but it was considered impractical (not to mention the fact that Boeing was fighting tooth-and-nail to get UA535 and US427 classified as pilot error - note that Airbus is *not* doing this in the case of AF447). The NTSB investigator in charge of the 737 issues literally had nightmares about another crash occurring - specifically nightmares in which he was called before Congress and asked why the type was not grounded after two fatal incidents.

Compare that situation - where you have two fatal incidents and an isolated issue, but not enough information to confirm it - with the situation around the Thales pitot tubes, where the issue was successfully solved in 12 incidents out of 13.

Boeing published a workaround which involved maintaining a higher approach speed in the 737 while the issue was being solved. I boarded a few 737s during that period, and I must confess I didn't feel 100% safe, but trusted the pilots enough to get us out of any difficulties.

Likewise, Airbus published a procedure to deal with UAS while the Service Bulletin was taking effect. Unlike with the 737 PCU, the pitot tube fix was known and was being implemented, and with the UAS procedure in place, theoretically things were safe. Unfortunately in the case of AF447 the procedure was not followed.

[NB : The Concorde accident was down to a failure mode which was not considered at the time the aircraft was designed, and no procedure could have saved the aircraft. With AF447, the failure mode was known and workarounds put in place (which, sadly, were not followed) - it's a completely different scenario. ]

[PJ2]

RetiredF4;

Further research on the AoA issues raised has yielded some interesting results.

Boeing has produced a document entitled, "Operational Use of Angle of Attack (http://www.boeing.com/commercial/aeromagazine/aero_12/aoa.pdf)". In the introduction, Boeing states:

A dedicated AOA indicator shown on the primary flight display (PFD) recently has been developed in cooperation with airline customers. The new indicator is offered as an option on the 737-600/-700/-800/ -900, 767-400, and 777 at this time.

During the development of the new indicator, discussions with airlines, the NTSB, and U.S. Federal Aviation Administration (FAA) pilots and engineers provided a unique opportunity to examine potential uses of AOA and the many existing uses that have evolved in recent decades along with advances in display and indication technology.

This article discusses the following:
1. Basic principles of AOA.
2. Airplane performance and AOA.
3. AOA measurement.
4. AOA indications and flight crew procedures in current Boeing production models.
5. Design and uses of a separate AOA indicator.The document answers my question:

Boeing and several operators worked together to develop the display format for an optional AOA indicator (fig. 12). The upper right location was chosen as one that can be accomplished without significant rearrangement of the existing PFD or electronic flight display formats. The indicator itself consists of an analog scale and pointer, and digital representation similar to displays of many other parameters throughout the flight deck.

Stall warning AOA is shown with a red tick mark, which will change position as a function of Mach number for those airplanes with Mach dependent stall warning schedules.

A green approach reference band is shown whenever landing flaps are selected. The range of the approach reference band accounts for normally expected variations in CG, thrust, sideslip, and other considerations.

Many AOA indicators used in the past have been of the “normalized” type, where AOA is shown in arbitrary units and scaled so that zero load factor is shown as an AOA of zero and stall is shown as an AOA of one. Normalized AOA on a commercial jetliner would require that Mach number be introduced into the calculation of AOA because stall AOA and buffet margins are a function of Mach number.

The indicator developed shows body AOA in degrees and is not normalized, which is related to the second objective above, that the indicator be useful when pitot or static data, and therefore Mach calculations, are unreliable because of blockage or a fault in the system. The pointer of a normalized indicator in this condition would behave erratically, making the indicator unusable.

With the non-normalized design, the position of the needle is a function only of sensed AOA. The red tick mark for stall warning may behave erratically in a pitot or static failure state, as may stick shaker, PLI, and speed tape amber and red bands. However, the AOA needle and digits will remain stable, and the indicator itself still will be useful as a backup for unreliable airspeed, provided the AOA vanes are undamaged.
I haven't seen a similar document from Airbus yet but will continue research. Essentially however, this is how an AoA indication should function for an airline crew and I think may address Owain Glyndwr's points as well.

[RetiredF4]

Well, would be too easy to just switch gauges from an fighter into an Airliner, didnt believe either that it would be possible.

PJ2
Here is the ECAM logic which triggers the stall warning from AoA in Alternate Law - this was posted earlier, (can't recall who to credit), but it may illustrate what is meant by the question:

So the AOA signal from the vane is available, the logic is there as well, it´s the engineers task to create a gadget which gives the necessary information for the required task. Use units or degrees, digits or a round gauge. the point i tried to make, its easy to use and doesn´t need sophisticated training.

@ Owain Glyndwr

The rhinos had different wings, stabilizers, Leading edge flaps, slats, BLC or no BLC, and therefore different onspeed values, different stall speeds and different wing rock behaviour. Therefore the numbers are only valid for one specific type, i estimate it´s the F4B. But that is no important point, as you tried to show how simple the system was built and that the indications lacked the accuracy necessary for air transport flying. I didn´t expect anything else and as mentioned before, i didn´t care. Despite that inaccuracy the phantom and other second generation fighters flew worldwide some millions flight hours with such a system and it kept thousands of pilots out of trouble.

Therefore the system might be inaccurate in todays standards, but it did its job well and never ever did i hear of an accident being caused by the inaccuracy of the AOA gauge.

Modern fighters still retain the indication of AOA in a modernized version, and those systems should somehow work in a air transport aircraft as well.

It´s not a question of technical feasability or of the necessary understanding and training, it´s a question of money and will.

@ PJ2 saw your post after i finished mine.

[DozyWannabe]

I haven't seen a similar document from Airbus yet but will continue research.

I know it's bleedin' Learmount, but here's an article from August last year (2011):

Airline pilots who've forgotten how to fly - Learmount (http://www.flightglobal.com/blogs/learmount/2011/08/airline-pilots-whove-forgotten.html)

Relevant snippet (in the comments) :

Airbus, and others, will be reviewing the aoa indicator option when all the wisdom is assembled in the BEA's final report. But that will not be for a while yet.

[PJ2]

RetiredF4, thanks for a good discussion on this important item. Perhaps we'll see some authentic change in these areas which should be relatively straightforward to implement. I also look forward to how the BEA Final Report's recommendations on this and other issues raised. The installation of an AoA indication was also an NTSB recommendation made in the Airborne Express DC8 accident in 1996.

Re your comment, "...it´s a question of money and will.", Yes sir, it most certainly is, especially in these times, or as someone put it so well here, "It's an indication of the value placed by a carrier on human life", or some such similar pithy statement.

Dozy, thanks for the link. The comment makes sense, given that Airbus is "in process" regarding all outcomes of the BEA work.

[RetiredF4]

DW

Retired F4
But he didn´t get the clue, otherwise he would have asked or even he would have taken over the aircraft like you mentioned, correct?

He did try to correct the PF verbally, so it's reasonable to assume he realised, or at least felt that something was wrong. I'm not an expert, but his speech pattern seems to indicate indecision. The captain has put the PF in charge - if the PNF takes over before the captain arrives, will it reflect badly on him if it turns out to be unnecessary? Perhaps he felt that correcting the PF verbally until the captain arrived would be the safest path to take

I made my point clear in this post (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-21.html#post7172639), bur let us look further into this matter:

2 h 10 min 11 What is that?
2 h 10 min 17 We’ve lost the the the speeds so… engine thrust ATHR engine lever thrust
2 h 10 min 22 Alternate law protections (law/low/lo)
2 h 10 min 24 Wait we’re losing…
2 h 10 min 25 Wing anti-ice
2 h 10 min 27 Watch your speed Watch your speed
2 h 10 min 31 Stabilise Go back down
2 h 10 min 33 You’re at Go back down
2 h 10 min 39 I’ll put you in in ATT (*)…
2 h 10 min 49 (…) where is he er?
2 h 11 min 00 Above all try to touch the lateral controls as little as possible eh
2 h 11 min 06 (…) is he coming or not?
2 h 11 min 21 But we’ve got the engines what’s happening (…)?
2 h 11 min 38 Controls to the left (and puts the SS to the full left stop)
(2 h 11 min 43 Captain on the deck: Er what are you doing?)
2 h 11 min 43 What’s happening? I don’t know I don’t know what’s happening
2 h 12 min 07 No above all don’t extend (the)
2 h 12 min 13 What do you think about it what do you think what do we need to do?


I stop there, because it gets worse later on.

Is that really a pilot monitoring in the loop?

2 h 10 min 11 What is that?
Probably the stall warning? Did he even recognize it as stall warning?

2 h 10 min 27 Watch your speed Watch your speed
He describes the symptoms not the cause. The cause was the pitchup, therefore the speed decrease, but he didn´t get it.

2 h 10 min 31 Stabilise Go back down
2 h 10 min 33 You’re at Go back down
Now 4 seconds later, he grasps that the altitude is off, that they are no longer in the assigned FL, no connection to the imminent stall if they continue like before....

2 h 11 min 00 Above all try to touch the lateral controls as little as possible eh

Now he starts to worry about the roll control, again no connection to the overall picture, an aircraft that is still gaining height, still losing speed, and is now doing some rolling oscilations due to impending loss of control

2 h 11 min 21 But we’ve got the engines what’s happening (…)?
another point that he has no clue. With engines working everything should be ok, but it isn´t...

2 h 11 min 38 Controls to the left (and puts the SS to the full left stop)

Now he is acting on his perception and guessing pattern not on knowledge, therefore he doesn´t mind the pitch, but he tries to stop the roll with full left SS

2 h 11 min 43 What’s happening? I don’t know I don’t know what’s happening

Now comes the relevation, when captain comes to the deck and asks "Er what are you(doing)?" he admits what we all know but are reluctant to accept, that he had no idea what was happening. He admits it himself.

2 h 12 min 07 No above all don’t extend (the)
At least he recognized what shouldn´t be done...

2 h 12 min 13 What do you think about it what do you think what do we need to do?

He was not able to give any information (despite a useful one) to the captain, but asks him what to do.

Tell me again, he had any plan on what was happening, why it was happening, and what could have been done about it. He was pilot monitoring, he could have used his whole concentration into that matter, but he didn´t get the picture.

[gums]

Thanks for the super link to Boeing, PJ.

@ other.....

You don't need to know the exact AoA you are at or the exact degrees that will get you into trouble. You just need relative values to be displayed. The Boeing link discusses the mach correction and configuration effects.

I once bumped the flap switch in my SLUF on approach and had only leading edge flaps ( they really smoothed out the buffet). So a poor cross check with speed had me maybe 10 or 15 knots faster than I should have been although I had the AoA bracket nailed in the HUD. No problem with stall, but a rain-soaked runway and long landing created a serious problem. Had to take the departure end barrier with my trusty hook and all was well ( except for meeting the boss and taking the heat for being stupid).

Although a decent AoA display could allow an optimum cruise, my personal thoughts are it should primarily help the crew prevent a stall and have an optimum approach AoA.

Seems the commercial airline folks do not want to implement a wide field-of-view HUD, but I can tell you that the sucker is invaluable in bad weather. Apparently the 737 fleet had the option a few years back, but I don't know if there are many being used. Some of the commercial pilots here could comment.

The HUD's I used were a lot easier to interpret than some of the panel displays I have seen here. Sure, they can be cluttered, but the ones I used had de-clutter options to help out.

Secondly, with the increasing deployment of FBW systems, HAL should use all available inputs to make the flight safer and easier than the old days. Why the AoA is ignored below 60 knots befuddles me. There are too many other sensor inputs to use than the airspeed or the AoA by themselves. So it comes down to the reversion laws and such, huh?

Lastly, and @ several here, the zero gee trajectory vastly reduces the chance of a stall. The 'bus keeps trying for the one gee Nz, and the trim system doesn't allow a trim otherwise. Compared with the Viper, we could trim the basic system for any gee from minus whatever to zero or about 3.5 positive gees. So a neat demo for the nugget was to run the trim all the way back and watch the jet do a hands-off perfect loop. As speed got low and we reached the AoA limit we stayed at the AoA limit until flying back down, when the gee limit came into play.

[CONF iture]

"Are you pulling up?"
"Yes. Shouldn't I be?"
"No - we're approaching stall - I have control."
"You have control."
The fact itself that such exchange becomes necessary highlights how information is suppressed by the Airbus sidestick concept.

RF4, I do salute your patience. Your explanations are clear.
I find amusing how DW, who sat down twice in a A320 simulator (but I don’t know about the experience of OC ?) is teaching you what flying is and more specifically instruments flying :
Even if you've got a yoke in front of you, unless you're in a life-and-death situation (which this wasn't at that point), you should take it gently, follow through and verbally confirm what you're feeling before you try to take over. I've never heard of a successful recovery requiring handing over of control where one pilot simply grabbed the controls from the other.
BTW Dozy, it is taking place everyday in the world, and not only in flying school. You don’t hear about it everytime it is successful.

The Airbus Service Bulletin was binding in terms of the work being *required*, not recommended - and the work having to be done by a given date. An Airworthiness Directive is the next level up where the type is effectively grounded until the work is done, and that wasn't really necessary in this case. ADs are only used when a fault is so severe that it is likely to result in the loss of the aircraft every time it occurs.
You have been answered on this point already (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-50.html#post6717915), so would you stop making the same erroneous comment.


My personal view on the AoA gauge on an airliner is that it has to be very simple and the training must suggest that anything approaching 5 degrees in cruise, or 15 deg at low level is inapropriate.

[DozyWannabe]

@RF4/franzl :

There's a missing piece of info that renders this statement interesting (my bold)

2 h 11 min 38 Controls to the left (Selects LHS sidestick priority and puts the [LHS] SS to the full left stop)

What this means is that his words could be referring to either of his actions, or indeed both. I've not had any definite confirrmation as to what he was likely to be implying here.

In any case, this doesn't seem to be perceived by the PF as a definite assertion of control, as 2 seconds later he's back on his own sidestick.

We're losing a lot of context in transcript and translation, so it's difficult to read too much certainty into what he was saying. Your point of view is that he was almost as at sea as the PF, which may be valid. But I see another way of reading it - which is that he was aware he might have had a better handle on things but wasn't sure, hence the nervousness about the arrival of the Captain, and his automatic delegation and deference to the same as soon as he arrived.

Was it a "pilot monitoring, [fully] in the loop"? Probably not.

But - prior to the Captain's arrival - he definitely seems to be more savvy than his colleague when he does open his mouth. His calls are correct (if non-standard) and his inputs more measured (although the latter takes some extrapolation). He puts all his faith in the Captain, even when the captain is not on the flight deck, and his confidence seems to wane when it seems that the captain (who has been called back from rest) seems none the wiser.

Either of us could be right or both of us could be completely wrong. I doubt we'll ever know for sure because the guys we're talking about are all dead. What we have to contemplate is the possibility that the Captain's decision to delegate the relief role to the junior F/O might have made the PNF reticent to act decisively.

We know that a steep command gradient can cause a PNF to not correct a senior PF (e.g. Birgenair, KLM4805) and we know that a more competent PNF will defer to his commander if they have been conditioned to defer to authority (e.g. Palm 90). What we have here is a scenario where a commander has made a decision on command gradient which runs contrary to that which might be expected, which is new to the study of HF.

The fact itself that such exchange becomes necessary highlights how information is suppressed by the Airbus sidestick concept.

I've said before that it's a drawback to the sidestick concept, but there are benefits in some scenarios which outweigh it.

I find amusing how DW ... is teaching you what flying is and more specifically instruments flying :

Not in the least. I'll happily defer to Franzl on flight and aerodynamics factors, but HF is an area in which we're both on fairly similar ground. Given that you (CONF) have repeatedly misrepresented the importance of airspeed to the alpha (AoA) max calculation, I guess we're even.

BTW Dozy, it is taking place everyday in the world, and not only in flying school. You don’t hear about it everytime it is successful.

Nor do you hear about successful sidestick handovers. Let me get this straight - are you saying that it *is* the norm on a scheduled flight for one pilot to take control from another without saying a word?

You have been answered on this point already (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-50.html#post6717915), so would you stop making the same erroneous comment.

OK - so the grounding date may be set in the future, but it doesn't change the fact that an AD would have been overkill in this case.

[Owain Glyndwr]

Retired F4

I was not unaware that the numbers were type specific. My point was simply that an AoA instrument for airline use would have to be more sophisticated than that on your F4 and that it might not give entirely reliable advice in a UAS situation. The Boeing explanation posted by PJ2 seems to bear this out.

With the non-normalized design, the position of the needle is a function only of sensed AOA. The red tick mark for stall warning may behave erratically in a pitot or static failure state, as may stick shaker, PLI, and speed tape amber and red bands. However, the AOA needle and digits will remain stable, and the indicator itself still will be useful as a backup for unreliable airspeed, provided the AOA vanes are undamaged.
I'm happy with that statement. And as I said I was not trying to argue against installation of AoA instruments, just to be clear on what they can or cannot give.

[RetiredF4]

DW
There's a missing piece of info that renders this statement interesting (my bold)

Quote:
2 h 11 min 38 Controls to the left (Selects LHS sidestick priority and puts the [LHS] SS to the full left stop)
What this means is that his words could be referring to either of his actions, or indeed both. I've not had any definite confirrmation as to what he was likely to be implying here.


You picked out the only text, where i added a shortened version of the explanatory text from IR3, which i should have markled as such.

Here is the original one and it is without doubt,

2 h 11 min 38 Controls to the left
And explanatory text in IR 3:
The pilot in the captain’s seat takes over the controls. The Captain sidestick is positioned left in stop position.

[DozyWannabe]

@franzl - Exactly. Where I'm at a loss as to decide what he meant by that statement is that he uses the words "Commande à gauche", which is ambiguous as to whether he is referring to putting in full left aileron, transferring control authority to the left-hand (Captain's) seat, or both - bearing in mind my understanding of French is limited to a translation dictionary.

The English translation is similarly ambiguous. I'm sure that if the BEA were certain as to what he was attempting to convey, they'd have translated it accordingly.

[Lyman]

@PJ2..."If the AoA indication adjusts for high Mach Number, (as the ECAM stall warning does when the Airbus is in Alternate Law), then the indication is useful."......

To be brief, does the ECAM (FCM) have time after a/p loss and Alternate 2 to recalc the STALLWARN AoA? As near as I can tell that would be 4 degrees at M.80? IOW, you are satisfied the "STALLSTALL" is legit?(the first one). Also, what does Bank Angle play in the ECAM's (display, via FCM logic?)

@DOZY.....

"Well, for a start I don't think there's an updraft in existence that could cause a heavy widebody to climb like that, plus an updraft wouldn't necessarily cause the pitch to increase."

All aircraft are susceptible to updraft, size and mass are not irrelevant, but by itself, the size and mass of 447 doesn't innoculate it from the effects of UPDRAFT. Yes, the PITCH may remain constant, but the AoA will not, it will INCREASE......Dozy, is it possible the presence of updraft may have caused the initial divergence in PITCH/AoA?

[DozyWannabe]

Lyman, all values are recalculated in real time - don't think of it as a home computer where tasks are prioritised differently and the machine will slow down as it has to process more. These computers are designed to process all the streams of information without missing a beat.

In answer to your question, the STALLSTALL at 02:10:10 was "G" induced and was silenced almost as quickly as it appeared. The *next* STALLSTALL was the real deal, however - and stayed on until the aircraft was well outside the designed operating envelope.

An updraft may mess with the AoA, but crucially the flight path does not indicate a climb of this nature, and nor does the DFDR data. This was a commanded climb.

[Lyman]

Doze....

"Lyman, all values are recalculated in real time - don't think of it as a home computer where tasks are prioritised differently and the machine will slow down as it has to process more. These computers are designed to process all the streams of information without missing a beat."

Yes, I know, it was a bit of a trick question, but not meant in any sinister way. What was the calculated AoA for STALLWARN at the instant of STALLSTALL? Via that data, you might guess what I am after.....

"In answer to your question, the STALLSTALL at 02:10:10 was "G" induced and was silenced almost as quickly as it appeared. The *next* STALLSTALL was the real deal, however - and stayed on until the aircraft was well outside the designed operating envelope."

Yes, but to acquire "G" what needs to happen? What silenced the WARN? G is a symptom.....

"An updraft may mess with the AoA, but crucially the flight path does not indicate a climb of this nature, and nor does the DFDR data. This was a commanded climb."

Yes, a commanded climb, no argument. Any other possibilities? Assistances?

The STALLWARN happened after loss of Autopilot, and the machine will not WARN in Normal Law, and we know (?) the aircraft was in ALTERNATE LAW, is it possible the a/c degraded merely (only) to acommodate the WARNING?

Lyman

[DozyWannabe]

I'm not in a position to do the maths right now, Lyman - but what I can tell you is that we got the same "G"-induced STALLSTALL in the sim at the moment I commanded pitch to 15 degrees - it was not caused by the updraft (the effects of which were simulated by the TRE using asymmetric thrust).

The "G"-induced STALLSTALL was caused by the sudden change in AoA caused by the pitch input, and was silenced because the airspeed was sufficient to climb and the values settled within limits. The behaviour would be the same with an electro-mechanical stall warning system, as far as I know.

[Lyman]

DozyWannabe I'm not in a position to do the maths right now, Lyman - but what I can tell you is that we got the same "G"-induced STALLSTALL in the sim at the moment I commanded pitch to 15 degrees - it was not caused by the updraft (the effects of which were simulated by the TRE using asymmetric thrust).

Yes, but in Which LAW was the SIM when you got STALLWARN...... And had you programmed "UAS" prior to unlatch?

In NORMAL LAW, the a/c will respond to a/p within certain limits of rate and deflection. It will also respond to rate ONLY..... So if G loaded beyond the limit of a/p, it will unlatch the a/p, by definition. So how are we to know what caused the a/p to unlatch? Speeds, or G, or "Rate". Or TREND? Inability to arrest TREND inside limits? This is an old question, but I thought I'd bring it up now that we're there, again.

[DozyWannabe]

Yes, but in Which LAW was the SIM when you got STALLWARN...... And had you programmed "UAS" prior to unlatch?

Alternate Law with no speed stability (A320 equivalent of ALT2) - the TRE failed 2 ADCs to simulate UAS. Trust me - these guys were thorough.

All evidence suggests that the autopilot disconnected because of UAS itself, as it was designed to do - not because of any external factors. Modern autopilots are designed to cope with moderate turbulence of the kind encountered by AF447, but you should know this because we've discussed that very subject before.

[Turbine D]

jcjeant,

Here is an interesting Powerpoint presentation that gives you the timeline and information on the pitot tubes. Slide #37 is a discussion between AF and Airbus, in French that perhaps you can translate the gist of for me. Hope you can open it...

http://henrimarnetcornus.20minutes-blogs.fr/media/02/01/151647242.ppt

TD

[Lyman]

Did you try without failing the ADR's? See, if PITCH (elevator) can induce a STALLWARN, transient, then the a/p has no business remaining active, wouldn't you program it that way? My point is that the a/p can quit without UAS.

Just on the prowl for negative synchronicity, aero style :ok:

[DozyWannabe]

Careful TD, your source is not exactly known for impartiality.

Did you try without failing the ADR's? See, if PITCH (elevator) can induce a STALLWARN, transient, then the a/p has no business remaining active, wouldn't you program it that way? My point is that the a/p can quit without UAS.

It took a lot of pitch input to induce that stall warning - way in excess of what the autopilot would order in terms of magnitude and speed.

Autopilots *can* quit as a result of extreme maneouvres, but that doesn't seem to be the case here - it was designed to cope with worse than what it was facing.

[Lyman]

One does not need PITCH input to trigger the STALLWARN, only "G", as you say.

If so, and you say it is, we would be looking for sufficient turbulence to trigger G that triggers the STALLWARN. This can happen in a/p, obviously, and the STALLWARN will remain silent. So I seek the data that conclusively shows us the PITOTS were clogged, and in failure. Powdery ICE is thus far unknown to me. Perhaps it is hitherto not well understood by others?

I do submit that STALLWARN can trigger without my touching the controls. No "extreme maneuvers" needed. The STALLWARN can be a TURBWARN as well? Even a WINDSHEARWARN ?

[HazelNuts39]

The brief stall warnings at 02:10:10 were the result of a combination of control inputs and turbulence (vertical gusts). That is evident in the traces of normal acceleration shown on page 42 of interim report no.3.

The gust velocities that can be derived from the DFDR data were posted here (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-12.html#post7159041).

The meteorological analysis by Tim Vasquez points to the possibility of a gust velocity of 23 m/s = 75.5 ft/s = 4527 ft/min based on the atmospheric temperature profile obtained in a radiosonde ascent from Fernando de Noronhas.

Powdery ICE is thus far unknown to me.Snow?

[DozyWannabe]

But Lyman, Stall Warning *did not* trigger until *after* the PF had taken manual control - that's a documented fact, down in black and white.

It would take considerably more external force to trigger Stall Warning or trip autopilot off than the aircraft was facing - this was all laid out in the TRE's debrief. This TRE is not an Airbus fanboy and I hold him in the highest regard.

I know you want to believe that the aircraft handed itself over in a practically uncontrollable state, but the evidence simply isn't there to back that hope up - not even slightly.

@HN39 - possibly. All I can tell you is that we got the transitory stall warning when I pulled the stick halfway back - so either the impact of turbulence was relatively negligible, or our simulated condiitons happened to hit a randomly-generated pocket that matched the conditions AF447 faced (which is on the face of it very unlikely). I don't believe the turbulence alone would have been anywhere near enough to trigger it, and neither did our TRE.

[Lyman]

What are the margins for error? A gust that does not impinge on the airframe sufficient to upset the Inertials can displace the AoA vanes, is this so?

[DozyWannabe]

What are the margins for error? A gust that does not impinge on the airframe sufficient to upset the Inertials can displace the AoA vanes, is this so?

At a guess, not enough and not for long enough to trigger a warning or autopilot disconnect. Remember that the AoA vanes are responding to the forward velocity of the aircraft and as such are subject to more inertia from those forces than an updraft could provide.

[Lyman]

Doze. No, not uncontrollable, not at all, I am trying to establish that the degrade could be the result of issues other than UAS. If turbulence was sufficient, and short cycling quickly enough to be masked by the inertial lag with airframe displacement, the AoA could be wack, short term, but disguised as unaffected in longer time cycles (seconds).

The 330 hasn't a part to play in this, except to say, she was there....

The vanes are every bit as sensitive to vertical as horizontal gusts....

[DozyWannabe]

Lyman - all I can say with any certainty is that what you're proposing is extremely unlikely. Which is to say none of us can know for certain, but based on the information we have it does not seem to be a plausible scenario.

The AoA value could be "wack" on one vane (which appears to be the case for a period), but as long as two of them are providing good data, it's not going to mess the systems up.

You'd need to be talking about a near-supersonic updraft to overcome the normal operation of those vanes, and the data suggests that the forces weren't even close to that.

[Lyman]

Unlikely? More so than Pitots filling with powdery ice? Prolly. Can you quote me a velocity for UP/DOWN air mass in a fully developed Cell? Or in its vicinity? I'm going to guess 100 knots. You? If not symmetrical, this movement can be quite a threat to life in the Flight Level?

Hardly supersonic, 100 knots (vertical) can deflect an AoA vane (s) what, five degrees?

[DozyWannabe]

Unlikely? More so than Pitots filling with powdery ice?

This was a known issue with the Thales AA pitot tubes, so not at all unlikely.

Can you quote me a velocity for UP/DOWN air mass in a fully developed Cell? Or in its vicinity?

No.

I'm going to guess 100 knots.

In which case it's going to come up against the inertia of 500+kts horizontal airflow and come off worse.

[Lyman]

NO. The airmass (flow) is no longer horizontal, relative to the a/c. The AoA is the new result of the relative displacement of the airmass.

And ground speed decreases...

[DozyWannabe]

Lyman, prior to climb, it's more horizontal than it is vertical. These vanes and the systems connected to them are *designed* to cope with conditions like this, otherwise you'd have minor emergencies as a result of every moderate turbulence encounter, which just isn't the case.

The Stall Warning comes after the initial pitch up command by a matter of a couple of seconds. The aircraft disconnected autopilot due to UAS and followed the PF's commands into the climb, not vice-versa.

[HazelNuts39]

100 knots (vertical) can deflect an AoA vane (s) what, five degrees?Simple: 11.3 degrees

[DozyWannabe]

Simple: 11.5 degrees

With no other force acting on them, right?

[HazelNuts39]

@Dozy,
I'm thinking in terms of flow angle. What forces are thinking of?

[DozyWannabe]

@HN39

The sharp up- or downdrafts that Lyman is describing against the flow generated by the aircraft's forward motion, and whether they would be enough to have a significant impact on the AoA value supplied to the systems.

[Lonewolf_50]

If I may revisit a tidbit about AoA from Retired F4

I don´t see the problem there, the information was present in the AF447 aircraft (Stall warning, FDR traces....), it was not displayed
AoA is information related to airflow over your flying surfaces, more or less a snapshot of "How is my aircraft (wing) flying?"

There is a bit of pilot scriptural canon, oft cited on these pages and in particular in the first two or three threads on AF 447, called Fly the Wing. Your AoA can tell you how your wing is doing, flying wise.

The A330 already detects and uses AoA information ... at least the robot does.

Why it is not considered by designers, airline companies, and others to be useful to the pilots remains a matter of design attitude, and conceptual attitude.

Choosing not to make that info available for the pilot's display looks to me like an attitude problem. (And again, I appreciate that the real estate in "display area" is precious, and is (allegedly) allocated with great care, particular in modern design processes. )

So who needs an AoA gage? What you don't know won't hurt you, eh?
Sorry, I disagree, with data point AF 447 a supporting tidbit.

Would a discreet AoA display have made the pilots aware, as they were flopping about, that they were in stall, a fact that seems to have escaped their notice?

Maybe, maybe not. Given my previous remarks on scan breakdown, there is ample argument against.

[HazelNuts39]

@Dozy,

An airplane moving forward at 500 kt encountering a sharp-edged upward gust of 100 kt would see the AoA increase by 11.3 degrees, and airspeed by 2%. That would increase the lift/weight ratio to about 1.8 and put the airplane in a stall. If the airplane maintains its pitch attitude, it would be accelerated upwards at initially approx. 0.8 g. As the airplane vertical speed increases the AoA reduces. The stall warning operates until the AoA is below the threshold. If the updraft lasts long enough, the airplane V/S will increase until it is equal to the updraft speed. The increased drag in the stalled condition would decelerate the airplane horizontally.

[DozyWannabe]

An airplane moving forward at 500 kt encountering a sharp-edged upward gust of 100 kt would see the AoA increase by 11.3 degrees. That would increase the lift/weight ratio to about 1.8 and put the airplane in a stall. If the airplane maintains its pitch attitude, it would be accelerated upwards at initially approx. 0.8 g. The increased drag in the stalled condition would decelerate the airplane horizontally.

OK, so taking this statement as the basis for our raw numbers and the fact that we know moderate turbulence does not as a rule lead to stall warnings or loss of AP, this means :


Either moderate turbulence does not reach 100kts vertical
Or the vanes and systems are designed to cope with this kind of anomaly


Personally I'm leery of getting too theoretical in this manner, as we begin to diverge from the facts on the ground.

Choosing not to make that info available for the pilot's display looks to me like an attitude problem. (And again, I appreciate that the real estate in "display area" is precious, and is (allegedly) allocated with great care, particular in modern design processes. )

Probably more a case of "no-one else does it" than anything else. The FPV display option comes pretty close.

Would a discreet AoA display have made the pilots aware, as they were flopping about, that they were in stall, a fact that seems to have escaped their notice?

Maybe, maybe not. Given my previous remarks on scan breakdown, there is ample argument against.

My position isn't too far from yours. If they couldn't diagnose a stall from the information they were provided, then it leaves the question open. That said, if it's easy enough to implement (and I'm pretty sure it is), that option should be exercised if for no other reason to provide more defence-in-depth than already exists.

[A33Zab]

A late reply on Your post #506 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-26.html#post7177438) concerning the BUSS.
I'm behind with all the posts.

Maybe this image is of some help?

AFAIK, there is no MACH compensation and amber/red area is not changed for speedbrake.

http://i474.photobucket.com/albums/rr101/Zab999/BUSS_SPEEDS.jpg

[Lyman]

Dozy

This argument is not to do with pilots, right, wrong, or indifferent. It has to do with the a/c, and what it is doing, strictly. AoA aside, my point is that there is room to entertain sensing/sussing anomalies with the autoflight, and the a/c basic modes to include Vselect, and work done prior to the Early June surprise sprung on the crew. This accident had its roots deep in the time frame prior to handoff, irrespective of ICE, turbulence, and Degraded Law. A working theory of Ice occluded probes suits me fine, but there is wiggle room in there for other sources of danger.... RetiredF4 I must say thank you for your work, your frame of PNF as a human, and not a foil for nothing more than a guess at CRM, well, thanks. There was ample confusion, and no less than two qualified pilots felt thoroughly in the weeds from the gitgo. If for no other reason, I will keep my objective view alive. There had to have been more than off target competence in play.

And HazelNuts39 thank you for a finer point on airmass/AOA. Five degrees? What was I thinking? :O

[DozyWannabe]

Lyman,

This is the definition of "Moderate" turbulence, but the bolding is mine:

Turbulence that is similar to Light Turbulence but of greater intensity. Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed.
or
Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude.

From : Tutorial: wind shear and turbulence (http://www.aircraftpilots.com/tutorials/safety/wind_shear.html)

The meteorological categories for wind gusts in general (as measured with an anemometer) are:
Category 1: weak — ≥ 5 m/s to <10 m/s
Category 2: moderate — ≥ 10 m/s to <15 m/s
Category 3: strong — ≥ 15 m/s to <25 m/s
Category 4: severe — ≥ 25 m/s
The meteorological categorisation restated for vertical gust measurement might be:
Weak — ≥ 16 fps to <25 fps
Moderate to strong — ≥ 25 fps to <50 fps
Strong to severe — ≥ 50 fps to <80 fps
Extreme — ≥ 80 fps (or 66 fps [20 m/s] might be used)

Note that Moderate doesn't even come close to the equivalent of 100kts (50fps = 29.6kts).

Outside of the numbers, I sat in the sim - I saw it happen and I *heard* it happen. I experienced an infinitesimal fraction of the concern and fear those pilots felt as the aircraft ran away from me. I stand by the assertion that the climb, warning and deviation from assigned altitude were predominantly caused by deliberate action by the PF.

I can't convince you - of this I'm sure. But I've gone to further lengths than I ever have before - assisted by people to whom I am in eternal debt - to prove that I'm not talking out of my ar*e here, and I'm as certain as it's possible to be that the aircraft did nothing to make things harder for them.

[jcjeant]

[NB : The Concorde accident was down to a failure mode which was not considered at the time the aircraft was designed, and no procedure could have saved the aircraft.Some off topic
Indeed this failure mode was not considered at the time the aircraft was designed
And for this kind of failure .. it's not possible to apply a procedure (pilot is not able to go plug the holes in F.O tanks) this failure required a structural correction ...
The problem is that along the life of the Concorde .. one of his main problem was the tires (many events) and so the design has to be reconsidered seriously (certainly after the important accident of Washington concerning tires and F.O tanks)
Another flaw design was the position of the tires relative to the engines ducts .. (this one was pratically impossible to correct .. lol)
But it was a possible solution for the dangerous tandem tires-F.O tanks ... and the solution was put in force .... after Gonesse ... unfortunately again too late for some people ...
Return to topic ...

[Lyman]

Dozy

Be careful not to extrapolate from guesswork. Initially, the Airline reported "turbulence fortes". We were not there, and the accelerations on the airframe leave some important data out. Why would the airline make such a statement? Who knows, and we do not know if there is data that is available, from the line, that is not released. Met based on satellite IR? Hmm......

Some cells can exceed 60000 feet in height, and contain monster cylinders of highly energetic vertical air. The crew inter briefed "somewhat more intense than that we just experienced, etc" . Once accelerated, the airframe can report calm accelerations, but be moving rapidly Up, or Down. Besides, I am not interested in turbulence, but in well developed symmetrical, and independent air mass, mostly, Up. Imagine an a/ c that is rising vertically, but with a reasonable Pitch, and consider that an airliner can climb whilst essentially level. Rapid climb....

I am suggesting the discrepancy in AoA and Pitch suggest such a thing. A thirty second bonus of climb, that paid out, and left the a/c hanging on her Fans, basically, all the way down. PostStall, I think it is a reach to get too critical of anyone on deck.

I am a fan of this a/c; whatever happened, look elsewhere for bias against this airframe.

[DozyWannabe]

The problem is that along the life of the Concorde .. one of his main problem was the tires (many events) and so the design has to be reconsidered seriously (certainly after the important accident of Washington concerning tires and F.O tanks)

BA made an alteration to the MLG deflection guard - AF did not.

Another flaw design was the position of the tires relative to the engines ducts .. (this one was pratically impossible to correct .. lol)

True - nowhere else to put them.

But it was a possible solution for the dangerous tandem tires-F.O tanks ... and the solution was put in force .... after Gonesse ... unfortunately again too late for some people ...

Well, BA altered the MLG setup, so one solution to that particular problem was in place on half the fleet years before Gonesse. However after Gonesse both operators did everything possible - and then some - to make sure the problem was completely resolved.

But there were only a dozen or so serviceable Concordes - it's a very different proposition compared to a type where the aircraft in service number in the hundreds or thousands.

But the point is that we're talking a catastrophic failure in which there is nothing any pilot could do to resolve the situation. This is very different from a UAS incident which is trained for even when there is no problem known on the type.

Be careful not to extrapolate from guesswork. Initially, the Airline reported "turbulence fortes". We were not there, and the accelerations on the airframe leave some important data out. Why would the airline make such a statement? Who knows, and we do not know if there is data that is available, from the line, that is not released. Met based on satellite IR? Hmm......

All data was released. The Airline reported "fortes" to the press, which makes sense if you bear in mind that most passengers - even frequent fliers - rarely encounter anything more than what is considered "light" turbulence to pilots

...and consider that an airliner can climb whilst essentially level. Rapid climb...

This one didn't though - the pitch change preceded the climb according to the FDR.

I am suggesting the discrepancy in AoA and Pitch suggest such a thing. A thirty second bonus of climb, that paid out, and left the a/c hanging on her Fans, basically, all the way down.

If the PF had kept her on a relatively level pitch angle then I'd be happy to entertain your theory, but this is not the case. He pulled up and continued to pull up throughout the sequence. As I've said, this climb was commanded.

This isn't about bashing the crew. Sure, they made mistakes - but even if they did, the fact that at least two of them were placed in a position beyond their knowledge and experience is not their fault.

[Lyman]

If the PF had kept her on a relatively level pitch angle then I'd be happy to entertain your theory, but this is not the case. He pulled up and continued to pull up throughout the sequence. As I've said, this climb was commanded.

Yes, Yes, Yes..... It was commanded. Yes there was a Pitch Up command. What evidence do you have that shows the PF's input was the only thing happening? How do you eliminate that some of the ascent was due airmass?

They are not mutually exclusive. See? The rate may have been in excess of PF's command? Additive, but masked in his Pull?

[bubbers44]

Highly unlikely since his full up commands were during a high climb rate from FL350 to 380 when it of course went into a full stall as all aircraft do handled that way.

[Lyman]

Yes. But remember "full up commands" doesn't net him any more than one g.

So actually the 7000 fpm lends credence to an assisted ascent (U/D). What is your opinion on melding 7k fpm with One G?

[DozyWannabe]

Yes. But remember "full up commands" doesn't net him any more than one g.

Not true. The system will allow anything up to 2.5G.

[Lyman]

In DIRECTLAW...... Pitch in AL 2 is g limited?

[bubbers44]

I think 1 G means you can not climb because as soon as you climb you will have to exceed it. Just a simple law of physics.

[Lyman]

I think max g in the climb was 1.68? One g in unaccelerated flight, yes. But accelerated rate (limit) is one g, ok?

[CONF iture]

Why don't you take a rest Dozy, you're writing nonsenses one after the other. It is getting hard to know which one to comment :
Alternate Law with no speed stability (A320 equivalent of ALT2) - the TRE failed 2 ADCs to simulate UAS. Trust me - these guys were thorough.
You fail 2 ADRs to switch to Alternate Law, not to simulate UAS.

Given that you (CONF) have repeatedly misrepresented the importance of airspeed to the alpha (AoA) max calculation, I guess we're even.
I have seen that before :
The aircraft *did* gave him alpha max, but alpha max was *limited* by the airspeed. To have increased the AoA much further would have induced a stall and probably would have killed most of the people on board.

You understand nothing about Alpha Max, you understand nothing about the protections, you didn't read the Habsheim report, and obviously understand nothing about aerodynamics ...
But please comment further, I'm curious to know how deep you'll go in this nonsense.

OK - so the grounding date may be set in the future, but it doesn't change the fact that an AD would have been overkill in this case.

Absolutely not. After the crash, EASA issued an AD, did it kill the 330 ?
Obviously the overkill has been to not treat the situation seriously enough before.

[RetiredF4]

A33Zab
A late reply on Your post #506 concerning the BUSS.
I'm behind with all the posts.

Maybe this image is of some help?

AFAIK, there is no MACH compensation and amber/red area is not changed for speedbrake.

Do I understand your insight correct, that the BUSS indications are not compensating for MACH or configuration and therefore the accuracy of the underlying AOA is therefore similar to the AOA indication we had in second generation fighter jets (F4)?

post of Owain Glyndwr (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-26.html#post7177879)
and
PJ2 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-26.html#post7177879)

[HazelNuts39]

RetF4,

The BUSS 'Slow' indication is adjusted for configuration as per the 'VSW-BackUp table'. (Second Table A in PJ2's post)

Since use of the BUSS is limited to FL250, the Mach at Vsw does not exceed 0.525 and therefore the threshold at 8.6 degrees is reasonable.

http://i.imgur.com/Uuw0K.gif?1

[Owain Glyndwr]

BUSS/AoA

Do I understand your insight correct, that the BUSS indications are not compensating for MACH or configuration and therefore the accuracy of the underlying AOA is therefore similar to the AOA indication we had in second generation fighter jets (F4)?

To be strictly accurate the actual AoA doesn't need to be compensated for Mach, but if you mean that the surrounding limits are no better than you had on your F4 then yes, I think BUSS is no different. In fact it cannot be otherwise; to get stall AoA for the display in all flight conditions you need at least some estimate of Mach number, which is in principle not available in a UAS situation. It might be, as gums sort of suggested, that you could get by with an approximate value of Mach derived from (for example) inertial speeds and barometric altitude - this would probably be good enough to give the sort of protection one is looking for in an AF447 situation but this is not, AFAIK a feature of BUSS as currently offered.

Otherwise, as I see it, BUSS functions exactly like your F4 AoA indication. In particular it gives a good guide for approach, or anything below about 0.4M and apart from the mechanics of the display BUSS does exactly the same job on approach as did your indexer lights.

[Clandestino]

Gentlemen, thank you for quite useful discussion on AoA gauges. I don't have definite opinion on the matter of necessity of equipping the airliners with them and anyway I spent about 150 hours warming up the front right seat on A320 of mid 200s S/N vintage, that had AoA indicators; small, round, analog, mechanical, pretty devoid of markings on dial face (just some units which might have been degrees or indices or whatever, no bugs or typical AoA markings) and set outboard of PFDs. There was description of the way system works in our manuals but there was not a single procedure based upon them. They did provide some inflight entertainment, especially in CONF 1 as they were not config compensated.

Nevertheless, I am not convinced that AoA gauge would have been necessary or even helpful to get AF447 crew out of their predicament as 1) UAS was never recognized and prescribed actions were never initiated 2) 36 other crews managed to do just fine under similar circumstances just relying on attitude and power 3) CVR and FDR don't paint a pretty picture; it seems that both pilots got utterly confused simultaneously and did not realize what was going on. In my opinion the IFR pilot that is unable comprehend the implication of the attitude he's putting the aeroplane into and does not realize what is that synthetic voice shouting "STALL STALL" trying to convey has zero chance of understanding what AoA gauge is telling him.

AFAIK Valpha max is the '1g' stall speed and is not g-sensitive.No. The wording of the manual does leave many possibilities for creative misinterpretation but I am pretty sure I've spent about a dozen hours overhead Lambourne, watching it creep up during turns.

Another misconception is that low speed cues are g-sensitive. They are not. They are alpha sensitive, just as the Cl is, therefore change of AoA will simultaneously change low speed cue position and wing lift which leads to Nz (colloquially: G) change. Applying post hoc, ergo propter hoc one can come to fallacious conclusion you need inertial source to drive low speed cue.

The gust velocities that can be derived from the DFDR data were posted here.

The meteorological analysis by Tim Vasquez points to the possibility of a gust velocity of 23 m/s = 75.5 ft/s = 4527 ft/min based on the atmospheric temperature profile obtained in a radiosonde ascent from Fernando de Noronhas.Valiant effort, but if you tried to prove there was significant turbulence that has affected the flight, you needed not bothered. Interim 3, page 42 shows difference between control induced Nz and measured one - which is indication of turbulence. +/- 0.4 G is moderate. Also very short lived.


Careful TD, your source is not exactly known for impartiality....but their PPS has sinister looking, dark figure of pilot on almost every page. Perchance compensating slight and not so slight distortions of facts with stage effects?

DGAC and EASA did know about far more than just AF's 9 pitot blockages. Consideration was given to changing SB regarding the replacement of Thales probes with Goodrich ones to AD somewhere in late 2008 but change was not effected. If it suits you, you may believe it to be a conspiracy. However, I have no problems seeing how the already more than twenty incidents that ended uneventfully could lead EASA to belief that every crew knows what to do when loosing IAS.

While Goodrich pitots perform far better than Thales, they are not perfectly immune from same type of clogging and their installation will not absolve the pilots from obligation to recognize UAS, know appropriate procedures for it and apply them. Law of self-preservation demands so.

Seems the commercial airline folks do not want to implement a wide field-of-view HUD, but I can tell you that the sucker is invaluable in bad weather.Actually, for last three years, I have been earnin' my daily bread by staring through wide angle Head-up Guidance System grafted onto my Q400. It's a wonderful thing. It has flight path vector. It has inertially driven energy caret so you know you'll lose or gain speed before IAS makes a slightest movement. It has speed error column on FPV so you don't need as much as look left across the HUD to check your speed, let alone perform quick glances inside the cockpit to check ASI on primary flight display while maneuvering manually during final approach. It's not direct measure or readout, but vertical distance between aeroplane reference and your FPV represents your AoA. There are pitch limit indicators preventing you from whacking your tail on takeoff rotation, unusual attitude recovery help, flight path limit showing you margin to stickshaker, TCAS RA flightpath (instead of VSI) guidance and lots of other neat stuff.

Is there a downside to it? Of course there is; it's too good and too easy to use and aeroplane can be dispatched with HUD or IRS failed so you are back to classic instruments scan. It's easy to let your classic scan get rusty so I make a habit of using HUD only on about half of the flights, to stay in shape.

Did my company buy this neat gizmo to make my life easier? Of course not. Our base gets pretty foggy in winter and HGS enables us to perform low visibility approaches down to 200m RVR and 50 ft DH, rather than 300m/100ft we had before HGS. It was cheaper to install HGS then to develop autoland capable autopilot cum autotorque.

[philip2412]

i`m quite in line with DW.we do not know,what happend when the cpt gave command to bonin.
maybe there was a discussion,a look,a grumble.maybe there were some frictions.
ithink we will read a lot about the personal and prof-history of PF/PNF in the BEA report.he was afraid that it will look like he took the first opportunity to go at bonin and that it may reflect bad on him if it was not necessary.
that`s why he was so eager for the return of the cpt: "come back and see was your `wunderkind` has done."
but to his surprise dubois didNt have a clue too.so he was reluctant to tell the cpt what bonin did,because now he thought maybe i`m wrong .
and bonin was afraid to brief the cpt. because he knew or felt that he had made a miistake.

[CONF iture]

One example chosen for a recent simulator LOFT (Line oriented flight training) exercise was the scenario of flying an A380 through a volcano ash cloud, which could simultaneously set off fire alarms on the flightdeck and elsewhere (thanks to smoke detectors) as well as flame out the engines.
In the simulator exercise, pitot tubes would also be blocked by ash.
It is getting pretty sporty at Qantas these days ... but not unrealistic at all I must say.

Is this really what you're trying to do? Eliciting certain reaction? Well, it's nothing personal, but IMHO airline pilot who enters the flight deck in night IMC and does not look for the clues on the instrument panel displays unprofessional behaviour, definition of which is not entirely arbitrary as not adhering to professional standards in aviation can be lethal.
No need to look, that's the first thing that will jump in your face : 2 yokes in that very unusual full aft position as soon as you enter the flightdeck. That's the first elephant in the room. Instruments reading only when get closer.

Second elephant in the room is the STALL WRN but that one unfortunately quits when the Captain is back. Still the Captain is fully aware of it as he could hear it when he was attempting to penetrate the flightdeck.

BTW who opened the door ? Did he have to use the emergency code to unlock the door ?
BEA, you have to produce much more that you did up to now.

For you Clandestino, too much to comment on your earlier post (467) (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-24.html#post7175819)
See you later.

[HazelNuts39]

Valiant effort, but if you tried to prove there was significant turbulence that has affected the flight, you needed not bothered.No, that was not the reason for posting. I referred to page 42 in the same post and at several earlier occasions.

[DozyWannabe]

I was wondering whether to dignify this with a reply, but I'm in a realtively good mood, so what the hell...

Why don't you take a rest Dozy, you're writing nonsenses one after the other.

Aah... I love the smell of ad hominem in the morning - smells like, er, ad hominem.

You fail 2 ADRs to switch to Alternate Law, not to simulate UAS.

Yes, and the TRE also failed the speed tape and altimeter on my PFD to simulate the conditions (the sim couldn't fail one or the other - only both), so I read the altitude from the standby. I wasn't giving Lyman an in-depth blow-by-blow account because I wrote about it in extensive detail on an earlier thread, I was simply giving an overall view.

Failing 2 ADCs switches to Alternate Law, as will a UAS event - that was the point I was making.

You understand nothing about Alpha Max, you understand nothing about the protections, you didn't read the Habsheim report, and obviously understand nothing about aerodynamics ...
But please comment further, I'm curious to know how deep you'll go in this nonsense.

Now let's see - Alpha Max isn't a protection, it's a variable value indicating the maximum AoA an aerofoil can reach before it stops generating lift (this is simplified, but you catch my drift). AoA is determined by the coefficient of lift, the formula for calculating which includes airspeed/Mach as a variable.

I hope I'm more-or-less right so far, and incidentally, damn you to hell for making me revise algebra for this. :8

Alpha Prot is a layer of protection within the flight control logic and is the first protection triggered as AoA approaches Alpha Max. This protection inhibits further pitch-up, retracts speedbrakes if deployed and limits bank angle to 45 degrees.

Alpha Floor is a protection within the autothrottle logic and is triggered at a predetermined point between the onset of Alpha Prot and arrival at Alpha Max, and primarily sets thrust to TO/GA.

Neither of these protections are a direct function of airspeed, purely that of AoA - but because airspeed is a variable used in the calculation of AoA there is an indirect relationship. In short, because you can increase your AoA by increasing pitch and by bleeding off airspeed, the relative pitch of Alpha Max (and the protection triggers) will decrease if you bleed off airspeed.

Alpha Prot and Alpha Floor both activate just short of Alpha Max, so when you state that the logic prevents Alpha Max from being reached you are technically correct. However, the reason for holding just short of Alpha Max is because it provides a safety margin. If Alpha Prot triggered at Alpha Max itself, it would take only a small gust to stall the aircraft and the protection would be much less effective.

Absolutely not. After the crash, EASA issued an AD, did it kill the 330 ?

Well no, but let's not ignore the fact that a significant percentage of the fleet had already had the SB work carried out prior to AF447. And it's not about "killing" a type, it's about airlines kicking up a stink because their aircraft aren't making money while they're on the ground.

Obviously the overkill has been to not treat the situation seriously enough before.

Your opinion, to which you are both welcome and entitled. In an ideal world I'd agree - but this isn't an ideal world. As I said, the risk posed by the Thales AA pitot tubes strikes me as considerably less than that posed by the 737 rudder PCU issue, and yet the latter was never deemed worthy of an AD with grounding to take effect immediately or otherwise.

No need to look, that's the first thing that will jump in your face : 2 yokes in that very unusual full aft position as soon as you enter the flightdeck.

Again with the presentation of your opinion as fact. A few posts back I listed four accidents just off the top of my head where the yoke cue was not acted upon. I'm not disputing that it *might* have helped, but it's a considerable stretch to claim it as a certainty (or an "elephant in the room").

I hate to use a driving analogy because it's not really the same, but when you've been driving for a while you rarely, if ever, *look* at the steering wheel. You're either looking out of the windscreen and reading the road, or glancing at your instruments - the latter of which causes you to look *through* the wheel, which after a time becomes automatic. I'd imagine it's the same for pilots, although they spent a much greater amount of time looking at the instruments and "through" the yoke, if there is one. I suspect this is one reason why there are so many incidents where the yoke position was not taken as a cue.

I'm genuinely curious as to why you think how he opened the door is so important.

[jcjeant]

I'm genuinely curious as to why you think how he opened the door is so important.Myself dunno if it's more or less important than all other movements .. actions and chatters of the pilots during this night
Anyways .. as this accident seem's very complicated ( flight deck and pilots matter) any clues can be important to find what happened ...
Actually we have ony the sparcely clues provided by BEA in the interim N°3

[Organfreak]

DW, in utter denial mode, wrote:

"Obviously the overkill has been to not treat the situation seriously enough before."

Your opinion, to which you are both welcome and entitled. In an ideal world I'd agree - but this isn't an ideal world. As I said, the risk posed by the Thales AA pitot tubes strikes me as considerably less than that posed by the 737 rudder PCU issue, and yet the latter was never deemed worthy of an AD with grounding to take effect immediately or otherwise.

Quote:
Originally Posted by CONF iture
"No need to look, that's the first thing that will jump in your face : 2 yokes in that very unusual full aft position as soon as you enter the flightdeck."

Again with the presentation of your opinion as fact. A few posts back I listed four accidents just off the top of my head where the yoke cue was not acted upon. I'm not disputing that it *might* have helped, but it's a considerable stretch to claim it as a certainty (or an "elephant in the room").

IMO, the 737 should have been grounded. This was a (poorly-decided) risk/benefit equation. There were, arguably, more than the three well-known accidents/incidents of rudder hardover/reversals. In hindsight, given the particulars of AF447, the Thales-equipped planes, too, ought to have been grounded. The crash sequence began there and ended hundreds of lives. "...risk...less serious"??? Oy veh! Here's how worried I am about airlines' profits: not one bit. If they can't be safe, they can jolly well fold their tents and get outta the business.

As for CONFiture's opinion, I (as well as others far more qualified) fully agree. Some opinions are more informed than others. It Just Make Sense. Your opinion seems to me to be arbitrary and capricious, with no offense intended, sir. Once more, with feeling, just because it didn't prevent some accidents proves nothing. As we all know, one cannot prove a negative.

[DozyWannabe]

Organfreak, please note the part where I said that in an ideal world, I'd agree with him re:ADs and grounding.

You're as free to believe what you wish about yokes as he is, but the fact is that he stated flat out that the yoke position would automatically have been noted. I provide evidence to refute that, while noting that it *might* have made a difference, and *I'm* the arbitrary and capricious one?

Look, I know that a popular conception among some has the Airbus FBW control system being dreamed up by a bunch of us computer geeks, none of whom had ever set foot inside a flight deck, but it just isn't true. I've mentioned this before, but the system was overseen by none other than the late Captain Gordon Corps, who was not only one of the most respected pilots of his day but also a colleague (and briefly the successor) of the late D.P. Davies, who wrote the seminal book on heavy jet operation still in use today. In terms of informed knowledge on the technical and operations aspect of airliners you simply can't get much more clout than that.

As for "It Just Makes Sense" - just about the most subjective statement in existence, because what makes sense to one individual may very well not make sense to others, and in terms of qualitative appraisal is about as useful as "My Dad Always Said", "It Stands To Reason" and "Some Bloke In The Pub Told Me".

[EDIT : Think for a second about the knock-on effect of grounding the 737. In a matter of days you'd be looking at a significant number of airlines - even the safest - folding completely through no fault of their own, if they couldn't find some way of making alternative arrangements. The only recourse they'd have would have been to seek compensation from Boeing, and before long you're looking at a collapse of a large chunk of the industry.

The A330 and A340 are not as widespread, but they make up a significant percentage of long-haul fleets these days.

As safe as air travel has become, the simple physics of what it involves means that there will always be an inherent risk even when everything is plain sailing. Mitigating that risk is a careful balancing act, and sometimes that means making a call that is not only cutting things finer than many (including myself) would like, but also has every potential of blowing up in your face. Real life by definition means compromising ideals and balancing risk on the occasions where the alternative would definitely be worse.]

[Organfreak]

DW:
Organfreak, please note the part where I said that in an ideal world, I'd agree with him re:ADs and grounding.

You're as free to believe what you wish about yokes as he is, but the fact is that he stated flat out that the yoke position would automatically have been noted. I provide evidence to refute that, while noting that it *might* have made a difference, and *I'm* the arbitrary and capricious one?


I was afraid you'd point out the "in an ideal world" part. I saw it; I should have addressed it. When it comes to air safety, I think we should strive for the ideal, even tho we all know that perfection is unattainable (something I learned long ago as a musician). "Good enough" is the friend of shoddy.

It is obvious that CONF's contention was an opinion-- good writing guidelines tell us that an opinion is obvious and the statement ID-ing it as such should be left out. But it the opinion of someone with a great deal of piloting experience, unlike yourself, or me for that matter. He did not state it as fact because it can't be fact, only a very-informed opinion.

As for the rest of your answer: it doesn't apply. When premier experts design things, we still have to look at mistakes made, ones that could not have been foreseen by any designer-god.

[DozyWannabe]

When it comes to air safety, I think we should strive for the ideal...

I think we're talking at cross-purposes here. I agree.

...even tho we all know that perfection is unattainable (something I learned long ago as a musician).

Me too.

"Good enough" is the friend of shoddy.

This wasn't a case of "good enough" as much as "the best that could be done in the circumstances". In this case guarding as much as possible against the risks inherent in doing things one way which could potentially have a bad outcome because to do things the other way would inevitably have a bad outcome.

good writing guidelines tell us that an opinion is obvious and the statement ID-ing it as such should be left out.

Whoever wrote those guidelines had clearly never encountered an internet forum before... :E

But it the opinion of someone with a great deal of piloting experience

Certainly, and if we were talking about airline operations, aeronautics and the like then I'd be all ears. But we're discussing an opinion he formed before he got that piloting experience on political grounds and one he has rigidly stuck to since. The equivalent with me would be over a decade of software engineering experience having no effect on the fact that I find Apple a loathsome company and have done since 1994 - not that it seems to have done them any harm over the last decade or so, so make of that what you will.

As for the rest of your answer: it doesn't apply. When premier experts design things, we still have to look at mistakes made, ones that could not have been foreseen by any designer-god.

Capt. Corps didn't design it, he was responsible for making sure that the system provided a safe and effective way of operating the aircraft, and doing so in a way that a majority of pilots would find relatively natural. By any objective measure, he succeeded. Seeing doing away with the yoke as a "mistake" is very much a minority opinion - and a dwindling one at that.

[Organfreak]

DW:
The equivalent with me would be over a decade of software engineering experience having no effect on the fact that I find Apple a loathsome company and have done since 1994 - not that it seems to have done them any harm over the last decade or so, so make of that what you will.


Just for fun, and something completely different (I'll never win this argument with you anyway), I've picked out the one part with which I entirely agree! Don't even let me get started on that!

[DozyWannabe]

@Organfreak

I'm not trying to win any arguments, I assure you. I'm just presenting rational evidence-based counterpoints to sweeping statements that we're expected to take as gospel.

Just as anyone asking me about Apple needs to take into account my visceral (to put it mildly) dislike of the company and their products when evaluating my words, so it goes with CONF iture and Airbus.

Right - let's get back on-topic.

[EDIT : Hostile? Nah - my natural manner is fairly jovial. Persistent almost to the point of being irritating? Guilty as charged, m'lud. :} ]

[Organfreak]

Your Honour, I submit that the witness is hostile.

:O

[Lyman]

Jobs and Boyd would have been buds. What makes Apple wildly successful is its genesis in product, and its disdain for tradition, and corporate corrosion, in Boyd's case "stale rank"....

Jobs..."Be Brutal, keep moving, and don't be satisfied..."THINK MOTION"

Boyd... "The victor is agile..."

Neither tolerated the status quo, and rejected explanations that took longer than two seconds...

The death of corporate agility started with the first committee.....

The evolution of the cockpit abandoned command in favor of democracy...

How precious....

[DozyWannabe]

The evolution of the cockpit abandoned command in favor of democracy...

Not at all. CRM may have been kryptonite to the "Captain God" philosophy, but in order to work effectively, a clear and well-understood command gradient is essential. Authority can be exercised without being a martinet about it.

In this case, both F/Os understood that they were under the captain's authority, but at least one of them seemed unsure as to his own.

[Lyman]

If you pause, you will note that you may have affirmed my opinion. The flightdeck from BEA information, only, suggests a gauzy and illdefined working group. I like your summary of the PNF's intentions. I don't necessarily agree, but here, the format failed due surprise, mainly. Leaderless enterprises seldom succeed. There was precious little to hold on to, and the environment had an unfriendly ambience. It cannot have been as bad as it seems, per BEA #3.

It simply can't....

bubbers44: Yes, I know.

[Lonewolf_50]

Dozy, your comment on the diagnosis bit misses the mark, handsomely.

If they couldn't diagnose a stall from the information they were provided, then it leaves the question open.
The point of the AoA gage discussion over numerous AF 447 threads hinges upon how easy it is to see, on an AoA gage, if you are or are not stalled.

The other means of diagnosing pale in comparison when it comes to simplicity, though one must admit that a stall warning horn is usually a clue that one must pay serious attention to one's performance! :eek:
(I guess on this next bit, but I suspect that the pilots in the cockpit associated stall warning with Airspeed being unreliable, and for that reason ignored it as assumed to be spurious ... may be wrong on that).

That said, if it's easy enough to implement (and I'm pretty sure it is), that option should be exercised if for no other reason to provide more defence-in-depth than already exists.

While that is my feeling as well, I do appreciate the counter to any of us recommending that added indication:

the plane isn't supposed to be flown into stall, and pilots ought to be aware enough in their flying to take stall prevention steps when warning of impending stall (via scan or other alerts) tells them that they are about to stall. AoA would help that, but it is an additional scan item, as a supplemental scan, which takes us back to "if the scan is breaking down, or has broken down, what will the pilot look at next, and what will register?"

The requirements folks can make a decent case against. It takes something like AF 447 to demonstrate where that reasonable approach may still not account for how that gage helps when needed most.

[Organfreak]

....but here, the format failed due surprise, mainly.

Mainly?

If you had said, "The format failed due to lousy/non-existent training, mainly" then I'd completely agree!

OF,
-"Afflicting the comfortable since 1950"

[Lyman]

They were surprised by their lack of training?

Comforting the afflicted, since.....

[Ornis]

Maybe it would help some drivers if the warning stall, stall was replaced by the instruction stick forward, nose down.

[NeoFit]

Hi,

'NAV ADR DISAGREE : RISK OF UNDUE STALL WARN'

But
'AIRBUS incite les pilotes .... ne pas tenir compte des alarmes STALL'
= 'Don't take care with Stall Alarm'
Make your choice

[gums]

Glad to hear from Cland that a few carriers are using a HUD.

His observations agree with mine to a large degree. That is, instrument approaches are much easier and safer. The down side is you can get spoiled and have to do the "human" reversion laws if the doofer fails. Just a few days until my digitized video is posted, and you will have no trouble seeing what was there to help.

I am not sure that any display should emphasize AoA in all flight regimes. However, even cruising, an AoA symbol referenced to the flight path marker would let you know within a second that something was gonna get bad and soon.

I have seen zero accident references to failed AoA sensors or inputs to the flight control system computers or even the old jets with basic control systems.

As some have pointed out, the basic airliners are much more sensitive to a mach stall than the jets I flew. Still, a display that shows a ridiculous AoA and low speed should be a clue for the pilot to use. You don't even need "bitching Betty" to tell you that you're about to stall. If that AoA bracket is way above the flight path marker, then....... duh?

Lastly, the solid-state HUD electronics were vastly more reliable than many old display systems. They either worked when you powered up or kept working unless you got hit by lightning.

[mm43]

Originally posted by NeoFit ...

'AIRBUS incite les pilotes .... ne pas tenir compte des alarmes STALL'Where was that quoted?

[AIRBUS encourages pilots to ignore the STALL warning]

[jcjeant]

Quote:
Originally posted by NeoFit ...

'AIRBUS incite les pilotes .... ne pas tenir compte des alarmes STALL'
Where was that quoted?

[AIRBUS encourages pilots to ignore the STALL warning]
AIRBUS encourages pilots to ignore the STALL warning :confused:
This is the procedure in force at the day AF447 crash
http://i.imgur.com/raVo1.jpg

At the end ... under TRAIN
Respecter les alarmes décrochage
Respect (take in account) the stall alarms

[PJ2]

Hello mm43;

I've seen words to that effect in past documents and I'm still searching through my archive. I found one item that hints that the stall warning may be false, but all other documents I've viewed thus far, (2002 to the present) having to do with UAS, state that the stall warning should be respected. But I know I have read somewhere that the warning could be false. The following may hint that the stall warning is/could be false but nothing in the document, (1997 & 2005) states that the warning should be ignored:

Any erroneous speed/altitude indication will always be associated with one or
more of the following cues:
· Fluctuations in airspeed indications
· Abnormal correlation of basic flight parameters (IAS, pitch, attitude, thrust,
climb rate); e.g IAS increasing with large nose-up pitch attitude, IAS
decreasing with large nose down pitch attitude, IAS decreasing, with nose
down pitch attitude and aircraft descending
· Abnormal AP/FD/A/THR behavior
· Stall or overspeed warnings
· Reduction in aerodynamic noise, with increasing IAS
· Increase in aerodynamic noise, with decreasing IASOn a related matter, the link to this Airbus presentation may have been posted previously but it is worth taking a look at it. The presentation was created in September, 2006.

Unreliable Speed - Latest Improvements (http://www.iag-inc.com/premium/AirbusUnreliableSpeeds.pdf)

[mm43]

Hi jcjeant, PJ2;

Thanks for your responses.

Well I've done a Google search and found the culprit article (http://henrimarnetcornus.20minutes-blogs.fr/archive/2011/08/20/af-447-avis-d-un-expert-les-omissions-subtiles-et-pas-anodin.html) for which a Google page translation can be found here (http://translate.google.com/translate?sl=fr&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fhenrimarnetcornus.20minutes-blogs.fr%2Farchive%2F2011%2F08%2F20%2Faf-447-avis-d-un-expert-les-omissions-subtiles-et-pas-anodin.html&act=url).

It is on an Airbus 'bashing' blog dated 20 August 2011, and I believe that it has previously been commented on in the PPRuNe threads, though I can't find a particular reference to it. The name Henri Marnet-Cornus is associated with it!

Now I've found it back in the AF447 Thread (http://www.pprune.org/tech-log/376433-af447-225.html#post5257772). Tilting at shadows?:}

[Flyinheavy]

@mm43
At the site that you cited, I found an interesting blog:

Il appartient aux seuls experts judiciaires* de faire enfin éclater la vérité (ce n’est pas la peine de compter sur le BEA) qui est :

Le 31 mai 2009lorsque le vol AF 447 décolle de Rio pour Paris, l’A330 F-GZCP n’avait pas un niveau de sécurité acceptable à cause du défaut des sondes Pitot Thales AA qui équipaient cet avion. La condition compromettant la sécurité qui en résultait, entretenue par l'absence d'une alarme spécifique "BLOCAGE PITOT" et par un système d'alarme décrochage non conforme au JAR 25, réduisait la capacité des pilotes à gérer une situation dégradée et a provoqué la destruction de l’avion et la mort de 228 personnes.

Alain de Valence, Hubert Arnould, Charles Magne, Eric Brodbeck, Michel Beyris.
Hope, I did not forget my French completely:

It is only up to legal experts* to finally reveal the truth (it's not worth counting on BEA), which is:

May 31st, 2009, when AF447 took off from Rio to Paris, the A330 F-GZCP did not have an acceptable level of safety because of the problems with
the Thales AA Pitot probes that equipped the aircraft. The resulting unsafe condition, sustained by the absence of a specific "BLOCKED PITOT" alert and by a
STALL WARNING SYSTEM not complying with JAR-25, reduced the pilot's ability to handle an abnormal situation and caused the destruction of the aircraft and the deaths of 228 people.

* Alain de Valence, Hubert Arnould, Charles Magne, Eric Brodbeck, Michel Beyris

Looks like a very bold statement "...NOT COMPLYING FAR-25", but on the other side, who knows....

Here is the link:
[URL="http://henrimarnetcornus.20minutes-blogs.fr/"]Les dossiers noirs du transport aérien

[CONF iture]

But I know I have read somewhere that the warning could be false.
This can be part of the F/CTL ADR DISAGREE when the RISK OF UNDUE STALL WARN STATUS MSG may mainly occur in case of AOA discrepancy and let's remember how the AOA data were different for AF447. Again, still not a single word from the BEA on this point ...

Also that information (http://www.pprune.org/tech-log/468394-af-447-thread-no-7-a-66.html#post7122035) is important regarding the stall warning and the way to deal with it.

[DozyWannabe]

@Flyinheavy:

I'd take *anything* that site has to say with a shovelful of salt. It is not remotely objective in any sense of the word and simply a repository for a disgruntled ex-AF captain to vent about his dislike for Airbus.

@CONF iture:

This might be a long shot, but is it not even slightly possible that the BEA factored that into the tests and found it to be irrelevant?

[PJ2]

Thank you CONF iture, yes, have seen this caution in various places both historical and recent. Also, I do recall coming across the OSV document more than a year ago and thought it prescient. The puzzle is, with so much information available prior to the accident, why did the accident occur at all? Getting information out to crews is always a challenge and doesn't happen in a few days or even weeks, and the sense of urgency is always contextual, so something perceived to not be an immediate threat receives less emphasis and dedication of what has become today, minimal resources, than other, "more immediate" concerns.

[Lyman]

I have more or less assumed that the crew rejected the STALLWARN as an anomaly in the procedure (mechanical), and that they came by that info through the Airline, via meter, Bulletin, or other......perhaps even the grapevine. Was AF so in the weeds they launched hundreds of flights with a cobbled together procedure that amounted to nothing more than "Scuttlebutt"?

Which of course explains clearly why the STALLWARN was ignored....

In the document, it specifically states the a/c can relay to the instruments
"NOSEUP/HIGH airspeeds" NOSELOW/SLOW airspeed, etc. IF Bonin was in NOSEHIGH, HIGH AIRSPEED (he obviously thought so, crazy speed) then NOSEHIGH/LOW SPEED (HE WAS), what does he do? Reject IAS? That makes the re-STALLSTALL partcularly poignant, just at the point when things were going the right way, etc.....His cues were there for NU/high speed, and did he accept them due the Bulletin as false? They seemed real....So, how to recover? Reference to VSI? It's pinned, how can he trust that, has anyone ever descended that way?

Any upset, a/c or pilotage, may interrupt the flight path, and once interrupted, it cannot be regained if systems become unreadable, and no trained response works to realign it. No going back, once lost. No trail of corn, no experience.

If true, it certainly explains things in a different light.

Worse, though, is what it says about the guesswork and negligence present around UAS in its 30plus iterations.

Were the crews and pax to be 'observers" on dozens (hundreds) of "test flights" whilst each occurrence involved "ad lib" recovery? Or no recovery (447)?

Challenge. Given the presence of STALL warnings, and unreadable/unreliable airspeeds, more information from the CVR is required. I cannot believe in the midst of this problem, the only conversation we see is what BEA have trickled out...

[HazelNuts39]

Which of course explains clearly why the STALLWARN was ignored....Was it? He immediately went to TOGA/15° pitch ...

[Flyinheavy]

@PJ2

If you read the AirCaraibe report, there they mention exactly the discrepancy of respecting S/W or not to.
ECAM status page stating:

"RISK OF UNDUE STALL WARNING" and
"UNDUE STALL WARNING MAY MAINLY OCCUR IN CASE OF AN AOA
DISCREPANCY"

Could it be, that the AF447 PF thought of Air Caraibe crew ignoring the S/W? Still would not justify pitching up to >10° at FL350.
What if he simply mixed up values of memory items below and above FL100 as he did UAS in the simulator not long before the accident.

Anyway, PNF would have had to at least call out "PITCH" and they probably would have broken the chain of events. Were they both so stunned, that neither of them thought of calling for the QRH?

May be BEA report to come will give more insight.........

[Lyman]

HazelNuts39

My only response can be that in his confusion, he was randomly selective about his response/not to STALLWARN. I apologize if I seemed narrow in my post, but his behaviour to me, shows a lack of recognition, as the others displayed, and emanated from an event that was not well known, had never been trained, and was a mere part of the LOC chain.....

how about.... "was variously ignored, and taken as fact..."

[roulishollandais]

AoA and HUD on commercial jets
Glad to hear from Cland that a few carriers are using a HUD.

The French Gilbert Klopfstein invented the HUD, :ok:and showed it in USA with MIT's congratulations. The French Armée de l'Air nor Zieglers (Aerospatiale, Airbus) did not like nor trust Klopstein and his HUD as he was Jewish. Klopfstein's HUD has been used on many aircrafts, i.e. F16, F18, Space Shuttle, etc. :rolleyes:

I have seen a HUD in a IT flying A310 (Air Inter, today included in AIR FRANCE !) around 30 years ago . :cool:

Something is sure, AF had that HUD and don't use it :ugh: not a question of price !

Would AF put it in the AF447, ... and crew trained, could you explain what would had been different ? :p

[Lyman]

Isn't HUD simply a panel "annex" with the most important cues displayed so all the pilot has to do is change focus (if even that) not field, with his scan? So the AoA would assuredly be displayed. "Eyes out" doesn't mean alot in 447's situation?

[CONF iture]

The puzzle is, with so much information available prior to the accident, why did the accident occur at all?
Because it is conflicting information - Nothing is clear.

Following the Air Caraibes events and the subsequent Memo, it was a known and accepted fact by Airbus that unreliable airspeed indication in cruise do happen and could be tricky. Airbus had to publish a clear and unambiguous note to all crews how to properly deal with such scenario that triggers a load of ECAMs but can be easily mastered if you do this this and that.
They knew that something was coming, hopefully not as bad as AF447, but something has to be done to inform crews before they face the situation.

[CONF iture]

I'd take *anything* that site has to say with a shovelful of salt. It is not remotely objective in any sense of the word and simply a repository for a disgruntled ex-AF captain to vent about his dislike for Airbus.
As a start Henri Marnet-Cornus has never worked for airfrance, so I would suggest anyone to take anything DozyWannabe has to say with a shovelful of salt if they don't want to be misguided or confused especially when the guy is talking about Alpha Max.

[CONF iture]

Challenge. Given the presence of STALL warnings, and unreadable/unreliable airspeeds, more information from the CVR is required. I cannot believe in the midst of this problem, the only conversation we see is what BEA have trickled out...
That the word STALL in a way or the other has not be pronounced once in 4 minutes time ... I also think we are served only part of the story by the BEA.

[Lyman]

The Truth requires no Seasoning.

And it may taste foul, granted. The Pilots are not Gods, and they don't have much to say about the operation of the business that provides their livelihood.

If the argument devolves to what did they know, and when did they know it? the personal histories of the various messages is irrelevant. Without a guideline for procedure, who would wager on the outcome of a situation that one time out of 30 was fatal? No one. Did Airbus, POST 447, issue a primer to pilots re: Stall? YES, Also, High speed handling? also YES.

If that is a finding, to my way of thinking, the pilots might not have responsibility for this accident at all.....

[aguadalte]

RetiredF4:
Well, last try. It works both ways, also in IMC and dark night and especially there. Your words, ....."You rely on the instruments to tell you what the aircraft is doing"..... and i fully agree and never ever said anything else. But flying does not stop there. A pilot will be and has to be in constant monitoring modus to compare the "what is the aircraft doing" to the "what should the aircraft be doing, which i call the expectation state. To be able to get this comparison you need the input value into the system . If you are flying manual in your 152 and you didn´t deflect any flight controls, because you didn´t want any change of the flightpath, but you observe a sudden bank, you know it is not your input, because you have your hands on the yoke and didn´t move any control surface. There must be another reason causing the input and that again might cause a diferent action from yourself.

Same if you are flying as PF, wether you made the flightcontrols change by manual input or by programming the automatics, you will know that it was your input. Will the PNF know ? He observes the change on the instruments and in a yoke aircraft observes the yoke movement in his lap, but in a non interconected SS aircraft? He has to guess.

Well, that works most of the time, because transport aircraft are and should be operated in a safe and preplanned mannor, so due to CRM it is common knowledge when something should happen in regard to flightpath or performance parameters change, because it is announced by PF, briefed before, or ordered by ATC. Therefore the expectation (we will now start descent, climb, turn..... ) shows as reality on the instruments.

When the sh**t hits the fan really bad like in AF447, the reality on the instruments is no longer nearing the expectation, the aircraft does not behave like expected (i´m in TOGA hehe..........I pulled back for quite a while....) and even both PF and PNF have now different understandig of things and the awareness, what the other guy is doing is lost. The corelation of the aircraft behaviour to the flight control inputs is lost, no valid feedback loop any more and therefore complete loss of situational awareness.

By the way, as far as i understand FBW systems it would be the same. If the system would loose the ability to recognize and measure its own input into the system, it would not be able to maintain normal control, like the dampers then counteracting the flightcontrol deflections.

I totally agree with you RetiredF4.

Further to the need of an AoA display unit, I believe this would be better than nothing but, unfortunately, that feature only addresses the stall issue. The question is wider than that IMHO. It has to do with the need (or not) for the PNF to "know" exactly what the other pilot is doing in all phases of flight and circumstances. How can I "see" if my copilot is over-controlling the aircraft? (Especially in the final stages of the approach?) How can I confirm that he is using all available performance of the aircraft to (lets say) perform an EGPWS terrain avoidance maneuver?
The actual (side-stick) system seems to leave one of the pilots out of the loop, throwing him into a situation in-which he is just watching the unfolding of events, once he can only take part, after his (delayed) interpretation of what was already "done" by PF. How can we interpret a "reaction" without knowing the "action" that led to it? What we "see" on instruments is the reaction of the aircraft to certain actions/inputs (whether done manually or via automation) but, as you say, there is an expectation created upon those inputs. We manage expectations along our flights. Long term (strategic/FMC/FMGC), medium term (FG/FCU) and short term (manual). Just like the 3 levels of automation... And when in doubt: click click...click click.
Children of the Magenta...

[Lyman]

But, like Dozy says, the Yoke has faults. There were accidents where the Yoke did not save? So SS has faults?

So with the Yoke shown to be fallible, the examination of the SS is:

1. Not necessary

2. Not relevant to this accident

3. Not sufficiently alarming so as to warrant a Grounding

4. All of the above.

5. None of the above.

Likewise, though the A0A would seem to have been helpful, (and it was on the a/c, but INVISIBLE), should the AoA be eliminated from the discussion? After all, how many accidents were not prevented by the presence of the AoA indicator?

Inquiring minds want to know.

[bubbers44]

With the inexperienced new hires coming to the right seat I think of my instructing days and how the instructor had to use his eyes to see if the student was going to be able to land without breaking anything until he approached soloing. It would be very difficult in a side stick airplane.

I think having the yoke as a reference in your sight made it easy to monitor. Even in the 757 I had an FO yank and bank to touchdown every landing and he said it was turbulence. Watching the yoke twitching I knew it wasn't. SS's might weigh less but they sure take you out of the real loop on what is going on.

[bubbers44]

I don't think it would take an ace to know at 35,000 ft you can not have the yoke in your gut. The PNF would have reacted but with the SS he didn't.

[bubbers44]

No it doesn't but if you are talking about visual scan I think the yoke being full back would make you react immediately leaving 35,000 for the impossible climb to 38,000 at the rate he was climbing before noticing the attitude indicator, don't you? They were too heavy to climb to FL370 because of weight and temp in turbulence so 1.3 buffet was their chart to climb.

Even if they used the AB 5 degrees nose up climb power memory items at their altitude it wouldn't have worked because unless they leveled out immediately they would have been too high and too slow and violated their RVSM separation.

[bubbers44]

I was responding to a momentary reply that is now removed about why the attitude indicator and 38,000 ft wouldn't have clued the PNF.

[CONF iture]

With the inexperienced new hires coming to the right seat I think of my instructing days and how the instructor had to use his eyes to see if the student was going to be able to land without breaking anything until he approached soloing. It would be very difficult in a side stick airplane.
And it is interesting to note that there is still no trainer in flying school equipped with such independant SS, probably for that very reason.
But now guys arrive on the RHS of a 320 with virtually no flight time at all ...

Question for you or aguadalte or RF4 or anyone who seems to share my view how the Airbus concept suppresses valuable information : What made Airbus to embrace such philosophy ?

[bubbers44]

Cost is my guess. I was able to bid away from AB so didn't have to leave Boeing planes my whole career. Loved Boeings because you always had control. Two button pushes and you were a DC3 style airplane. You were 100% in control. It made flying easy.

[CONF iture]

You could still have given a try and like most of us you would have loved it. With time and perseverance we learn step by step what’s inside and how to master it and recognize the weak points. Of course you can still fly it like a DC3 except you’re not allowed to force direct law, so you’re still vulnerable to a Qantas mishap ... but what are the odds after all.

[Old Carthusian]

I am still left with the question - would a yoke or visible side stick have helped in this accident? The conclusion given the information we have is no. The PNF had all the information he needed and didn't need to guess what was happening from seeing the position of anything. Gentlemen this is just clutching at straws and displaying your prejudices not objective examination of the situation. Look to the psychological and 'soft' features of this accident not whether you can see a side stick or not. Instruments, gentlemen, instruments.

[gums]

The lack of visual cues or "feel" of the other pilot's control position is a bogey man.

You see what the jet is doing and question the other dude/gal and then get in the loop.

I have soloed dozens of troops in the Viper with the sidestick and zero feedback and zero stick movement ( actually about 1/8 inch after first few came on line). That's the family model. In the SLUF we had no two-seat trainers so first flight was solo. Flew close chase and talked to the troop.

As several here have stated over and over, it's the instrument crosscheck and determining if the jet is doing what it is being commanded to do, or not.

[bubbers44]

Ask any normal flight instructor how he would like to teach basic flying and see what they say. You need visual feedback of what the controls are doing. Once you have an advanced student you might get by with no visual feedback.

[Old Carthusian]

However, this is an advanced flight situation - not a basic training exercise. No visual cues outside the aircraft at all.

[Lyman]

I think bubbers44 meant cues direct from controls, not outside.

[Mr Optimistic]

Surprising that the cmd didn't command the pf as to his action and ask, repeatedly, what he was doing. On the evidence, could an assertion that all the crew were aware of the pf inputs be refuted ie there was a consensus in the fd? All the ss discussion seems to be that the pf was a secretive incompetent renegade and if only the others had known and acted!

And if the pnf had to get up to let the cpt in, why didn't the cpt immediately take his seat ? The mystery of the undone straps was never resolved was it?

[aguadalte]

CONF iture:
The provocative answer to that question would be: "because Airbuses were designed by engineers but unfortunately flown by pilots"...
My personal guess is that they wanted to brake with the "old" concepts. Starting with a blank sheet, they wanted to show the world that they were able to design an all new aircraft reflecting the European potential for innovation. "An aircraft made against pilot's errors"...
I had the opportunity to meet Pierre Baud, when I was invited to Toulouse in the early ninety's, to fly one of their A330 testbed aircraft. That was my first experience with a FBW aircraft (before that, only Boeing and A310's) and I personally had the chance to verbalize my worries in this regard (no feed-back on SS, added inputs on SS, lack of need for trimming, ATS in step of Auto-Throttles) and he explained to me that this was a new concept of aircraft and that the FBW represented not only an evolution on the handling characteristics but also the chance to save on weight and that the final goal would be MFF and communality.
I do understand that at certain point of the design work, AI engineers had to take options. They have opted for this system and there is no go-back, at this time. It is not yet clear for the majority of the pilot's community that the system is wrong. There's a great deal of pilots feeling quite comfortable flying SS without feed-back, but as Donald A. Norman wrote on his:
THE PROBLEM OF AUTOMATION:
INAPPROPRIATE FEEDBACK AND
INTERACTION, NOT OVER-AUTOMATION
Donald A. Norman
University of California, San Diego
As automation increasingly takes its place in industry, especially high-risk
industry, it is often blamed for causing harm and increasing the chance of human
error when failures occur. I propose that the problem is not the presence of
automation, but rather its inappropriate design. The problem is that the
operations under normal operating conditions are performed appropriately, but
there is inadequate feed back and interaction with the humans who must control
the overall conduct of the task. When the situations exceed the capabilities of the
automatic equipment, then the inadequate feedback leads to difficulties for the
human controllers.
The problem, I suggest, is that the automation is at an intermediate level of
intelligence, powerful enough to take over control that used to be done by people,
but not powerful enough to handle all abnormalities. Moreover, its level of
intelligence is insufficient to provide the continual, appropriate feedback that
occurs naturally among human operators. This is the source of the current
difficulties. To solve this problem, the automation should either be made less
intelligent or more so, but the current level is quite inappropriate.

[A33Zab]

To solve this problem, the automation should either be made less
intelligent or more so


The automation was made less intelligent with ALT LAW (PROT LOST),
the human (pilot) was in control...but failed.

Conclusion?......green light for MORE automation.

[DozyWannabe]

It's always distressing when everyone's talking and no-one takes a second to listen:

I don't think it would take an ace to know at 35,000 ft you can not have the yoke in your gut. The PNF would have reacted but with the SS he didn't.

Just to point out a few indisputable facts:

Northwest Airlines Flight 6231 (B727) - PNF had yoke in his lap during stall, did nothing.
Birgenair Flight 301 (757) - PNF had yoke in his lap during stall, did nothing.
Air Florida Flight 90 (737) - PNF had yoke in his lap during stall, did nothing.


The provocative answer to that question would be: "because Airbuses were designed by engineers but unfortunately flown by pilots"...

...I know that a popular conception among some has the Airbus FBW control system being dreamed up by a bunch of us computer geeks, none of whom had ever set foot inside a flight deck, but it just isn't true. I've mentioned this before, but the system was overseen by none other than the late Captain Gordon Corps, who was not only one of the most respected pilots of his day but also a colleague (and briefly the successor) of the late D.P. Davies, who wrote the seminal book on heavy jet operation still in use today. In terms of informed knowledge on the technical and operations aspect of airliners you simply can't get much more clout than that.

[Diesel8]

"It is not yet clear for the majority of the pilot's community that the system is wrong."

Oh really?

If the accident/incident rate were different between AB and Boeing, then you would have a point, but as we know, it isn't.

I hate to ask, but I surmise you do have time on the bus?

[CONF iture]

Thanks for the reply aguadalte. Interesting.

The automation was made less intelligent with ALT LAW (PROT LOST),
the human (pilot) was in control...but failed.
That kind of aircraft is so dependent of the quality of the inputs received through the numerous probes. If a doubt exits on any of those probes or sensors, the aircraft should reverse straight to the most simple law : the direct one and get rid of any kind of automation. To have quietly autotrimmed 13 deg NU under those conditions has been a killer.

You see what the jet is doing and question the other dude/gal and then get in the loop.
That's the advantage of fully visible yokes, no need to wait or ask, you are continuously in the loop.

As several here have stated over and over, it's the instrument crosscheck and determining if the jet is doing what it is being commanded to do, or not.
Again, it has never been question to doubt what the instruments are telling.
It is question to know what has been commanded, or not. How do you know if you can't be aware of the command inputs ? Maybe the aircraft is doing something that has not even been commanded by the PF.

Fully visible flight control commands place you one step ahead in the thinking process.

[Flyinheavy]

@CONF iture


To have quietly autotrimmed 13 deg NU under those conditions has been a killer.



I share some of your views, but this statement seems a little strong, as it has been showed by BEA.3 that PF did use N/U SS inputs nearly all of the time for whatever (wrong) reason.

Means I would concur if he would have tried to overcome a NU trimm with N/D inputs...

[Diesel8]

I don't recall many incidences where the SS bus has not responded appropriately to sick movement, one that comes to mind is the cross wired stick, that reversed roll. F/O took command and landed safely.

As for AF447, the PF almost continuously applied nose up, when he applied nose down the A/C responded.

After all this discussion, I still cannot figure out why the pilots managed to stall this aircraft, it seems it was a simple case of loss of airspeed?

[DozyWannabe]

Fully visible flight control commands place you one step ahead in the thinking process.

If - and *only* if - you see them. Many haven't.

Question for you or aguadalte or RF4 or anyone who seems to share my view how the Airbus concept suppresses valuable information : What made Airbus to embrace such philosophy ?

CONF, if you only ask people who already agree with you, you're less likely to learn anything new. Most of the useful stuff I've learned has come from people who either agree partially or don't agree with me at all.

Pretend this isn't coming from me if it helps, but at least one of the reasons for the switch was that the yoke was designed around cable control. Before hydraulic assistance you needed a control column that size to have the leverage to move the flight surfaces. The 737 still requires it because it's manual reversion mode is cable-operated. None of the widebodies did, as they were fully-hydraulic, but it was kept anyway with a complex electro-mechanical feedback system in place. Same with the 757. The 777 and 787 use a software-controlled feedback system, the code for which is in all likelihood more complex than every system on the A320 put together. The A320, like the 757, was a narrowbody that was fully-hydraulic, and therefore one of the main reasons for having a yoke was no longer there.

With a fully-hydraulic system, one of the main reasons for having the controls interconnected - i.e. the need for both pilots to exert leverage when control cables are damaged - also goes away, so Airbus developed a system that would attempt to enforce one pilot in control at all times. Being an airliner and not a trainer, the need for one pilot to feel what the other is doing was greatly reduced, and losing the interconnection also removed the possibility of pilots fighting over the controls or having to work against the force exerted by an incapacitated pilot's body interfering with the yoke.

Being able to see the primary flight control movement buys some time, but only a matter of a second or two, if that. And if a PNF is really unsure about what their colleague is doing, they can take control at the press of a button and lock them out by holding it down (although would only be recommended in extreme circumstances - e.g. EgyptAir 990).

If you come at the problem having already concluded that the yoke is a superior control method in every sense, then you don't find this stuff out because you don't want to. Similarly if someone were to come at it from a conclusion that the SS is better, then they'd close their ears to what you're saying. Believe it or not, I do take on board the advantages the yoke has - but I don't think it's enough to say it's better or safer in every respect, because in some scenarios it clearly isn't.

[rudderrudderrat]

Hi DozyWannabe,
If - and *only* if - you see them. Many haven't.
If you read the cvr transcript, both crew knew they were close to the stall.
Air Florida Flight 90 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Air_Florida_Flight_90)
“16:00:45 CAM-1 Forward, forward, easy. We only want five hundred.
16:00:48 CAM-1 Come on forward....forward, just barely climb.
16:00:59 CAM-1 Stalling, we're falling!
16:01:00 CAM-2 This is it. We're going down, Larry....
16:01:01 CAM-1 I know it!”

Birgenair Flight 301 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Birgenair_Flight_301)
“The co-pilot and relief pilot both seemed to recognize the approaching stall and tried to tell the captain, but did not intervene directly, possibly out of deference to the captain's age and experience.”

That's a CRM problem. The other pilots recognised the approach to the stall.

[Lyman]

Reliability and performance are not the same thing. No one expects any system to actually cause a problem. The key is how is the performance, when there is a problem.

Two different things. When in a bad deal, what is the performance expectation?

To say that one system is not compromised in its design consideration because a separate system has been present in a fatal, is frankly preposterous. In the vast majority of cases, controls are not an issue. Can controls become an issue? Yes, I would say.

"Climb, then" "But I have been pulling for some time". Right. For some length of time, unknown to the other two crew, PF was inputting up elevators.

Can they have their time back? Request a do-over? What could have been the solution had the PF's yoke been in his lap, visible immediately at any given time?

Rest

[DozyWannabe]

If you read the cvr transcript, both crew knew they were close to the stall.
...
That's a CRM problem. The other pilots recognised the approach to the stall.

It's been a while since I read about Palm 90, but I'm pretty sure that F/O Pettit knew they were stalling from reading the ASI, and that the Birgenair F/Os were using a combination of the ASI (which was working on the F/O's side) and ADI (the other F/O in the jumpseat calls "ADI!" out several times during the sequence). Neither made any reference to yoke position.

I know they were aware they were close to the stall. The point I was making was that even with the yoke telling them that their respective PFs were pulling into the stall, they either did not see it, or saw it and didn't do anything about it.

[Lyman]

As non-flying pilots, their duty is to notice attitude, not the controls that produced it. "Yoke,Yoke"....... That makes them an instructor, and is not in the quiver of a highly charged cockpit. Even in emergency, habit and tradition.

"not acting" and "acting" are on two sides of a VERY thick coin.

Case in point: 447 PNF, apparently aware, and 'irritated' does not say, "Use your Stick, Push Nose down." He points to VS, and, due protocol, waits for the correction. None is forthcoming, yet he persists, unto STALL, apparently. That part of Training may need a looksee.

[Lonewolf_50]

If that is a finding, to my way of thinking, the pilots might not have responsibility for this accident at all.....
Lyman, I think you are stretching a bit too far there.

Look at the nose pitch behavior: it appears that the crew on the flight deck did not correct the nose attitude, nor maintain assigned altitude, within normal parameters during the early course of the malfunction, before it became something worse. It began as a comparatively mundane malfunction of a system known in the past to have some vulnerabilities. It does not appear that the malfunction they were faced with was novel, nor a "first time in class" malfunction.

Given that with similar malfunctions, most crews in 30+ similar events, who dealt with attitude and altitude excursions of varying magnitude ...

got their planes sorted out
remained flying
remained unstalled
prevented a malfunction from becoming an emergency.
then this crew's inability to do so stands out.

I do not wish to disrespect the dead, but I think that, with some of the info available to us via released CVR extracts, the crew has at least some responsibility, even if a BEA conclusion is reached that training, command decisions by the captain, documentation, systemic problems at Air France, probe replacement schedules, et cetera, are major contributing factors.

That "zoom climb" is to me doubly inexplicable, given that the crew were very aware of their altitude limitations for that sector of the route. Their discussion was recorded, to the effect that actual versus forecast temps at altitude did not permit a climb to a higher altitude that they had planned for (or left as an option) before takeoff.

The Airspeed was unreliable, but Altitude was not.

I cannot think of a professional airline pilot who considers a 1000 or 2000 foot altitude deviation (no less a 3000 foot deviation) as something other than very serious, and in need of immediate correction unless something else very untoward is also occurring at the same time.

[Lonewolf_50]

As non-flying pilots, their duty is to notice attitude, not the controls that produced it. "Yoke,Yoke"....... That makes them an instructor, and is not in the quiver of a highly charged cockpit.

Respectfully, no.

In multiplace aircraft, when the other guy isn't doing great at flying, you do indeed resort to "instructor" type techniques and behaviors in order to get him back into the ball game. In some cases, you have to take the controls, but more often it is simpler to talk him back into the game.

"Lower your nose ...
Roll left ...
Ball's out to right, step on it ...
Add power...
We are sinking -- POWER POWER POWER! ...
The Gear's UP! Wave OFF! (Go Around!)"

All of these are solid actions / calls that in some situations must be initiatied by a good co-pilot (PNF) that are also "instructor" actions/calls.

The two roles overlap; they are not mutually exclusive.

[Lyman]

I make no moral judgment as to these two accidents, and you are correct. BUT, going from the evidence, can you say some political reluctance was not in play? You quote proper procedures, certainly. In these tragic accidents, I believe your "best practice" was not folowed, as it should have been. Do you see these as "best practice," then? It is occasionally extremely difficult to act without "equality" in the cockpit, that is my point.

As to 447, "Responsible" remains to be decided, and since it is in Court, some percentage value will be apportioned to whomever the principals are determined to be. If crew were briefed, officially, to ignore STALLWARN, where is their culpability? So that means that up til three seconds after a/p handoff, the pilots were totally on the hook. The first STALL,STALL is intriguing, and we do not know its genesis. PF did not "TOGA/15 degrees at this point, and did later, so to me, that indicates the first warnng was ignored. If PNF was concerned about something "What was that?" we do not know what it was.

fifty four seconds total of STALLWARN, and not a word......do you think that odd, Lonewolf?

[B]@Lonewolf...."That "zoom climb" is to me doubly inexplicable, given that the crew were very aware of their altitude limitations for that sector of the route. Their discussion was recorded, to the effect that actual versus forecast temps at altitude did not permit a climb to a higher altitude that they had planned for (or left as an option) before takeoff. /B]

Not inexplicable and the reason is this: The evidence. My take is that the PF was unaware of his climb, and his instruments were not helping him to decide the correct attitude, plus a concern for Overspeed. Another factor could be an uncommanded ascent. Make no mistake, his pull on the stick caused climb, but can we eliminate the a/c climbing on her own? In additiion to? The VS and the altitude gained are remarkable, and the initial inputs of PF were not commensurate with ROC, imho. How can the a/c sustain 1.68 g and the cockpit not remark? ROLL masking the VS accelerations? Columnar airmass, ~ +100?

[Organfreak]

Lyman,
It is occasionally extremely difficult to act without "equality" in the cockpit, that is my point.

B-but Lyman, that was supposed to have gone out with high-button shoes, or at least hula hoops, after numerous accidents were blamed on poor/no CRM. How could, in this day and age, cultural customs trump professional procedure???

And, if there was such a problem, it seems to point to: they would rather die (and kill everyone else) than speak out-of-turn! It's hard to fathom. I'm wondering something that can never be answered: Were they both so panicked that they froze and forgot everything? (Deer, headlights.) It sure looks that way.

[Lyman]

Howdy Organfreak.

Given the evidence, that the yoke was certain salvation, and nothing of consequence happened, you are correct in assuming some sort of hard to explain vector of behaviour. I count three times that I was very close to dying, once in a hang glider.

I did everything I could do, in all three situations, and each time I experienced a very calm feeling; in looking back, I could not have done anything differently.

BTW. I'd like to recapture that feeling, and like most humans make it my way of life. But without the danger.....

[jcjeant]

Hi,

DW
The question can be also ... why Boeing keep the yoke even on their last aircraft conception ?
Why they don't choice the SS ? .. as it's less weight .. etc ...

[aguadalte]

Diesel8:
I hate to ask, but I surmise you do have time on the bus?

Well, my friend, you made me go back to my logbook only to find out that I have about 7760 fh on FBW aircraft and 7740 fh on non-FBW.

I guess I'm a lucky guy ;)

[DozyWannabe]

The question can be also ... why Boeing keep the yoke even on their last aircraft conception ?
Why they don't choice the SS ? .. as it's less weight .. etc ...

In part because it gave them a selling point by taking advantage of the backlash among some following the A320's entry into service. FBW as a concept was already proven, so they could focus on the backdrive software, which was probably more complex than anything Airbus could have attempted back in 1982.

That was all window-dressing really though - where Airbus had and still have an unassailable lead over Boeing is the ease of conversion between types - in which the design of the Airbus FBW flight deck played a crucial role. Because there is more commonality between the Airbus FBW types than could be remotely possible between Boeing's, it didn't make sense for Boeing to try to retrofit all their existing types with 777-based controls. In that sense, Boeing having been around for longer and being responsible for the most popular airliner in the world actually proved a disadvantage.

[EDIT : Just to try and clarify - the debate over Airbus, FBW and automation frequently misses the point in a lot of ways. The A320's automation is not a great deal more advanced than that of the 757 (Boeing's 3rd-gen narrowbody at the time).

The fact is that Airbus found themselves in an almost unique position in the early 1980s. Because their only existing types catered for a specific market, and because that market was near-saturated, it meant that they could expand without encumbering themselves with A300 commonality.

One of the great misunderstandings about Airbus's much-publicised cost savings to airlines with the new FBW types was how the savings were achieved. It wasn't really to do with greater automation, and it definitely wasn't an attempt to de-skill pilots - it was to do with ease of conversion. By designing the flight deck of their narrowbody and new widebody types to have unprecedented commonality with each other, theoretically the cost to airlines of conversion training could be drastically reduced. Boeing had made inroads on this theory by designing the 757 and 767's flight decks to be very close functionally, but Boeing still had the legacy types (727, 737, 747) to contend with. Airbus had a relatively clean run at doing it across their entire range, with the exception of the A300/310 (which had nowhere near the market penetration of the older Boeing types).

As such, the fundamental design brief was to put together a flight deck that could be installed in anything from a twin-engined puddle-jumper to a four-engined widebody long-hauler and as near as possible have the only difference to the pilot be the reference numbers. Obviously if you're feeding back the control surface resistance to the stick that's not possible - so with the help of some of the best pilots in Europe they set about making a design which would feed back all the information available in a more traditional setup, but would fulfil the design brief. Some compromises had to be made, but the position Airbus enjoys now is a testament to the soundness of the design they came up with. ]

[Lyman]

I think the Bus markets well, but let us not leave out the ease of transitioning to flight in the first place, the entry level. How much of this "consumer friendly" sales Pitch has to do with ease of operation? That is the foundation for the chronic knock on the Bus cockpit, imho.

[DozyWannabe]

All of it, Lyman - that's why people like Gordon Corps were onboard.

Leaving aside the sidesticks for a moment, the rest of the design was probably one of the most ergonomically friendly in airliner history. One of the reasons I miss 411A is because he could wax lyrical on what a pig the early 707 cockpits were (and different for every customer initially!).

The fact that I could take off, follow the FD and land the sim with minimal instruction* - having not been in a real aircraft cockpit since I last climbed out of an AEF Chuckmunk 18 years ago - shows that it is pretty intuitive to the novice.

[* - Not to underplay the instruction I did get, which was concise, to the point and everything I needed to do it - I can't thank those involved enough. ]

[IcePack]

Lyman re your post of not reacting to Stall Stall.
A lot of years ago I was involved in an investigation into a wheels up arrival.
The GPWS was triggering for 17 seconds. None of the 3 crew heard it. However it was as clear as a bell on the CVR area mike. 1st thing to go under stress is hearing so I guess the 447 didn't hear the stall warning.

[Organfreak]

jcjeant wrote:
The question can be also ... why Boeing keep the yoke even on their last aircraft conception ?
Why they don't choice the SS ? .. as it's less weight .. etc ...


I realize that your question is only rhetorical, but I have read recently (but can't remember where, dammit!) Boeing's statement of their FBW design philosophy. It made it clear that they insist upon realistic FC feedback.

[DozyWannabe]

I realize that your question is only rhetorical, but I have read recently (but can't remember where, dammit!) Boeing's statement of their FBW design philosophy. It made it clear that they insist upon realistic FC feedback.

The question then becomes, why do they insist on that - given that the realistic feedback is entirely artificial?

I had a pop at answering that question above. I believe it has more to do with corporate philosophy and the need to stake out different ground from their competitors than anything else - plus they weren't in a position to reap the benefit of radically overhauling their control methodology in the way that Airbus were.

@IcePack - there are visual stall warning cues too, including the bright red master caution light going off right in front of you and various cues on the PFD.

(And whatever else you may think of Airbus, they were on the money - going from a distant third in terms of western airliner sales to being able to duke it out with Boeing for the crown on an annual basis.)

Lyman (below) - spelling corrected.

[Lyman]

Chipmonk....that is a Catholic deHavilland?

[Organfreak]

DW:
The question then becomes, why do they insist on that - given that the realistic feedback is entirely artificial?

Come on, Dozy, you know the answer as well as anyone. Because it is entirely realistic. It does its job, it works.

As to your second point, I'm sure that's true.

DW:

(And whatever else you may think of Airbus, they were on the money - going from a distant third in terms of western airliner sales to being able to duke it out with Boeing for the crown on an annual basis.)


Great Jumping Jehosaphat! That is so disingenuous I forgot to sneer. MD merged into Boeing. That pretty much took care of the rest of the competition. (Though Boeing titularly bought-out MD, Boeing's board and leaders suddenly became largely MD, and that's when they began dropping lots of balls. Run by money wonks instead of engineer wonks.)

But I digress.

[HazelNuts39]

... why Boeing keep the yoke ...Because American pilots are more conservative than their European collegues?

[DozyWannabe]

Come on, Dozy, you know the answer as well as anyone. Because it is entirely realistic. It does its job, it works.

Until it doesn't (just because it hasn't gone wrong yet doesn't mean it won't). One of the things I used to find amusing about the A v B debate were the B people who swore up-and-down that Boeing's latest models weren't entirely computer-reliant, and the presence of the moving yokes proved it.

Great Jumping Jehosaphat! That is so disingenuous I forgot to sneer. MD merged into Boeing. That pretty much took care of the rest of the competition.

They'd overhauled the ailing MD by the early-mid '90s. In any case the point still stands, because the MD/Boeing merger would have produced a company that consistently outsold Airbus year-on-year if Airbus themselves hadn't done something about it.

[EDIT : I'm sure I've said this before, but as an aside, I wonder what would have happened if Boeing had elected to shrink the 757 rather than stretch the 737 for their (then) next-gen narrowbody. ]

[rudderrudderrat]

Hi DozyWannabe,
One of the things I used to find amusing about the A v B debate were the B people who swore up-and-down that Boeing's latest models weren't entirely computer-reliant, and the presence of the moving yokes proved it.

http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf
"11.3 Design Philosophy.

More will be said of these specific features later. What should be noted, however, is that none of these features limit the action of the pilot. The 777 design utilizes envelope protection in all of its functionality rather than envelope limiting. Envelope protection deters pilot inputs from exceeding certain predefined limits but does not prohibit it. Envelope limiting prevents the pilot from commanding the airplane beyond set limits. For example, the 777 bank angle protection feature will significantly increase the wheel force a pilot encounters when attempting to roll the airplane past a predefined bank angle. This acts as a prompt to the pilot that the airplane is approaching the bank angle limit. However, if deemed necessary, the pilot may override this protection by exerting a greater force on the wheel than is being exerted by the backdrive actuator. The intent is to inform the pilot that the command being given would put the
airplane outside of its normal operating envelope, but the ability to do so is not precluded. This concept is central to the design philosophy of the 777 Primary Flight Control System."

It seems to have the benefit of computer assisted warning - but not interference.

[DozyWannabe]

It seems to have the benefit of computer assisted warning - but not interference.

It's a different approach certainly, and one that seems to work just as well. As I'm sure you're aware, you have to put the A320 a fair amount out of whack attitude-wise before the non-alpha related protections kick in.

The point I was making (albeit not very clearly) was that those early nay-sayers were adamant that an entirely computer-controlled flight control system could not be trusted under any circumstances, and were labouring under the misapprehension that the 777 didn't have one.

[jcjeant]

Hi,

DW:
that an entirely computer-controlled flight control system could not be trusted under any circumstances,Seem's to me that it will be better if:
An entirely computer-assisted flight system controlled by the pilot ....

[DozyWannabe]

An entirely computer-assisted flight system controlled by the pilot ....

Which is true of both Airbus and Boeing's FBW systems. Unlike Boeing, Airbus's system does have hard limits, but I'd be prepared to bet you could count the number of times those limits have been encountered in 24 years of service on your fingers and toes. For example, the bank angle limit is 67 degrees - any further and you'll risk a spiral dive and structural damage. Those limits are not there to inhibit pilots, they're there to prevent structural damage and loss of control.

[rudderrudderrat]

Hi DozyWannabe,
Those limits are not there to inhibit pilots, they're there to prevent structural damage and loss of control.
That was the design concept - but sometimes the programmers haven't anticipated every possible eventuality. There have been several heavy landings where the ELAC computers prevented the authority the pilots wanted.
Accident of an Iberian Airbus A320 in Bilbao (http://www.iasa.com.au/folders/Safety_Issues/others/Bilbao.html)

I bet the LH A320 crosswind landing pilots wish they had full aileron control once the landing gear touched the runway. I know they should not have been there in the first place (X wind outside limits) - but reducing the maximum amount of available aileron control on touch down doesn't make sense to me.

[DozyWannabe]

@rudderrudderrat

If there's a case to change it, they will. It wouldn't have been the programmers making that call in any case, it would have been the aeronautical engineers and the test pilots*. Even the best and most experienced of us codemonkeys have to stick to the specification we're given. A good software engineer will tell you how to implement a specification in the best way, but they can't change the spec themselves.

I suspect that even with a conventional airliner, the engineers would push back on changing a behaviour that manifested itself outside of the operational limits - those limits are there for a reason after all.

[* Just to reiterate the point in general - Software Engineers do not define the limits within a FBW control system. That is the remit of the aero engineers and test pilots. ]

[RR_NDB]

Hi,

Why Airbus SAS (former AI) introduced SS in commercial aviation?
(http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies-4.html#post7185277)

[bubbers44]

23,000 hrs flying in my career has never required a computer to protect my bank limit. Maybe we just need to train pilots, not computer operators. AF447 had computer operators because they rarely flew the aircraft. They just monitored the autopilot. If we continue to use autopilot monitor people to fly we need an absolutely fool proof automated airplane that will never disconnect, no matter what. Is that what we want? Why?

Stall recovery was quite simple, lower the nose and add power not pull up into a deep stall at 38,000 ft. We need qualified pilots back in the cockpit now. Not a 300 hr new guy that will only monitor the autopilot for thousands of hours then become a captain. Does anybody disagree? UAS is an abnormal, not an emergency. Every jet has a checklist to keep you flying with no airspeed. pitch and power for weight and altitude. Or just use the altimiter since it is working.

[mm43]

We need qualified pilots back in the cockpit now. Not a 300 hr new guy that will only monitor the autopilot for thousands of hours then become a captain. Does anybody disagree? Which begs the question, "How do you get 'hands on' experience?"http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/icons/46.gif

This post by Good Business Sense (http://www.pprune.org/7179690-post102.html) in R&N is possibly food for thought.More time in the flare ?
There are an increasing number of very well known airlines today who put 200 hour ab initio pilots straight into 747/A340/777 long haul operations.

If you consider the usual SOPs regarding the use of autopilot and that many would be very lucky to get 20 sectors per year (post cruise pilot years) I would guess that the average amount of hands on per year would be in the order of 100 minutes. Of course, the hands on would mainly come after the aircraft has been configured and stabilized 4-6 miles out by the autopilot.

So some 10-15 years down the road when command comes around they would have, post initial training, about 16 to 25 hours of handling, in 2-3 minute bursts, under their belt.

To quote the old joke, I think I've got more time in the flarehttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif

Just a thought

[Diesel8]

Aguadalte,

Wasn't slagging on you, just asking.

Besides, glad you found your logbooks so easily, last I looked for mine I wound up in the dark attic!

[CONF iture]

I share some of your views, but this statement seems a little strong
The statement is strong I agree. Still, I did not want to write the killer, but just one element in the puzzle that lead to the final result.
I gave my opinion below but we can discuss further.

http://www.pprune.org/6727692-post1024.html

http://www.pprune.org/6812692-post343.html

[Lyman]

"That’s even worse Lyman, under Normal Law, the system logically thinks it’s time to cancel autotrim by reaching Alpha Prot or slightly above, but when the situation has degraded and Alternate Law is active, the system thinks it’s smart to autotrim all the way whatever the Alpha …" CONFiture.

And to me, the sequence of events should be seen in its logical context... Once climbing, the THS stopped trimming @ ~3 degrees. That would indicate that NORMAL Law obtained...(overspeed react, a/c?)

At 2:10:22 "....ALTERNATE LAW..." PNF

Once slowed, with AoA increasing, the THS re-invigorated, then the a/c STALLED.

By the evidence, and knowing the controls LAW profile, one could conclude that the a/c was reacting to an actual overspeed at 2:10:07. The STALLWARN could have been triggered by an A0A at or above STALLWARN trigger (bug).

Once slowed by ( 'elevators only' climb, ) the a/c switched to ALTERNATE2 and the THS started cranking again....

Other than ruffling feathers, I have not seen that this could not be so.

In the case of controls LAW, the evidence points to overspeed followed by Law degrade, then STALL, with an active THS.

Not knowing the length of time the a/c takes to suss/WARN Overspeed, or ALTERNATE LAW, it is conceivable the direction and fortitude of the airmass, plus controls input (to include THS), could easily cause: climb/upset/STALL......

In any case, the aircraft seems to be telling us that @ Alpha Prot (STALLWARN) the THS is stopped. And that once degraded into Alternate2 in the climb, the THS starts trimming UP once again.

As above....

[mm43]

At 2:10:22 "....ALTERNATE LAW..." PNF[BEA]"The flight control law switched from normal to alternate at about 2 h 10 min 05. The alternate law adopted was alternate 2B and it did not change again subsequently."

The PNF took 17 secs to note and verbalize the LAW change.Once slowed by ( 'elevators only' climb, ) the a/c switched to ALTERNATE2 and the THS started cranking again....The aircraft was effectively stalled before the THS passed 5°NU.

[A33Zab]

And to me, the sequence of events should be seen in its logical context

This is Lyman's logic!.......very well corrected by mm43:ok:

Compare for differences and similarities:

F-GLZU A340-300 22 july 2011:

Avherald Link (http://avherald.com/h?article=44280b2a/0006&opt=0)

BEA reort (French) (http://www.bea.aero/docspa/2011/f-zu110722/pdf/f-zu110722.pdf)

[mm43]

Originally posted by A33Zab ...
Look for differences and similarities:Yes! No wonder the BEA want to know what is being said in these cockpits.:uhoh:

[HazelNuts39]

Find the differences to the AIRPROX incident to A340 TC-JDN on 2 october 2000:
The turkish pilots responded slightly earlier to the zoom climb. (Turkish 18s, AF 90s).

Isn't it strange that pilots immediately respond to an overspeed warning, but fail to notice a zoom climb that (if it hadn't been protected) would have brought the airplane close to stalling?

P.S. Another notable difference is a change in the control law, which now leaves high AoA protection mode with SS in neutral during 0.5 seconds when the AoA is below AlphaProt.

[aguadalte]

mm43:
The aircraft was effectively stalled before the THS passed 5°NU.

Yes...but the question is: did they have enough pitch command to put the nose down when the THS reached more than 13º nose up?
(please, before replying that the aircraft could have been manually trimmed by them, please consider that apart from direct law flight sim situations, (done my flight sim check today;)) FBW pilots may have the chance to never touch a trim wheel during their whole life...)

[Turbine D]

Hi Dozy,

Have been reading the ongoing back and forth on A vs B, sidesticks vs yokes, FBW control, etc. I know you are knowledgable on Airbus control systems and defend Airbus practices when challenged. So in that there is not much going on relative to AF447, I though it might be good to put some things in perspective, A vs B.

Boeing designed the 767 & 757 aircraft in tandem with the idea of shared cockpit design features so that pilots could obtain a common type rating to operate either aircraft. Boeing continued to selected conventional control systems for both aircraft.

Airbus had a difficult time initially selling A300 aircraft as a replacement for either the MD-10/11 or the Lockheed Tri-Star and decided on a new approach to the soon to be A-320 which would compete against the Boeing 737. For this airplane and those that followed, a FBW system was designed and the yokes used in the A-300 were replaced with sidesticks.

Boeing finally decided to introduce a FBW system for the new 777 aircraft being considered. In the design of the Boeing 777, Boeing changed the way it went about designing aircraft. On previous aircraft, Boeing pretty much selected the design and presented the aircraft to the customers. For the 777, eight major airlines had a role in the development of the aircraft. The airlines were, All Nippon Airlines, American Airlines, British Airways, Cathay Pacific, Delta Airlines, Japanese Airlines, Qantas and United Airlines. It was the first aircraft completely designed entirely on a computer. It was decided to retain conventional control yokes rather than change to sidestick controllers. Along with traditional yoke and rudder controls, the cockpit featured a simplified layout that retained similarities to other Boeing aircraft. However, the FBW concept used was slightly different than what Airbus designed for the A320. The differences are in philosophies.

Airbus designed its FBW jets with built-in protections or hard limits. Boeing, on the other hand, believed pilots should have the ultimate say, meaning the pilot can override onboard computers and therefore built-in soft limits. So here is the issue. Should pilots or a computer have the ultimate control over a commercial jetliner as the plane approaches its design limits in an emergency? There were and are strong arguments by pilots on both sides of the debates. Some pilots are of the opinion that computer protection of the A320 and subsequent designed aircraft are very good whereas other pilots support the Boeing philosophy that they must have the final say in controlling the aircraft. There are valid arguments both ways.

One argument was the Boeing 757 Cali Columbia crash where the pilot didn't retract the speed brakes after receiving a terrain avoidance warning. In a A320 the retraction would have been automatically accomplished by the computers. On the other hand, the A320 Habsheim crash was the result of the pilot going below a 50 ft threshold in which the computers assumed the pilot was trying to land. The plane did exactly what it was suppose to do according to the computers and landed in the treetops. The first five accidents involving A-320 aircraft were the result, in one way or another, of misunderstandings between the computers and the flight crews. Obviously this has improved through pilot training, familiarity with the computer control systems, and refinements of the computer control systems by Airbus. Over time, there have been 50 incidents on A320 aircraft involving "glass cockpit blackout". The most serious occurred on a United Airlines aircraft where half of the ECAM displays, all radios, transponders, TCAS and attitude indicators were lost. Due to good weather and daylight conditions the pilots were able to land at Newark airport without radio contact.

I should point out that the Boeing 777 FBW aircraft have suffered only two hull-loss accidents and 6 other "occurrences" with 1,009 aircraft currently flying. Neither hull-loss accidents involved the FBW system. One was BA's mishap landing at Heathrow (engine problems) and the other was an onboard fire in the cockpit due to a faulty oxygen tube while the plane was at the gate in Egypt, there have been no fatalities.

Personally, I would fly on any aircraft in commercial service that either A or B have produced. Each are different in some respects but both share very good safety records when you take away the outlying causes such as hijackings and deliberate crashes. I flew on A320s back and forth to the West coast of the US last week, uneventful, pleasant flights and a nice comfortable seating arrangement by Delta Airlines.

Just trying to be fair and balanced when it comes to a statement like this:

Until it doesn't (just because it hasn't gone wrong yet doesn't mean it won't). One of the things I used to find amusing about the A v B debate were the B people who swore up-and-down that Boeing's latest models weren't entirely computer-reliant, and the presence of the moving yokes proved it.


They'd overhauled the ailing MD by the early-mid '90s. In any case the point still stands, because the MD/Boeing merger would have produced a company that consistently outsold Airbus year-on-year if Airbus themselves hadn't done something about it.

The merger of Boeing and MD had nothing to do with the commercial aircraft side of the ledger. IMHO, it had everything to do with the military side of the ledger as MD was near or at bankruptcy. The US DOD arranged a "shotgun wedding" to save the production of several lines of military aircraft from folding. At the time, there was no redeeming value on MD's commercial side of the ledger.

[PJ2]

Turbine D - a fine post, thanks.

[bubbers44]

The 757 Cali crash changed our memory items to stow the speed brakes but it probably wouldn't had made any difference anyway. I was flying to Panama City that night and there was no moon so when they screwed up and headed east through the hills to Bogata because both outer markers had the same designater they could not see the terrain. My FO questioned our visual that night overflying the airport at 5,000 ft approaching over the Pacific and said all we have to clear now are sailboat masts.

I was offered the same approach straight in as them and out of courtesy declined it because of the people we lost in that crash. It isn't a hard approach but doing the ILS from the south side seemed like the thing to do after that awful crash.

[mm43]

aguadalte;Yes...but the question is: did they have enough pitch command to put the nose down when the THS reached more than 13º nose up?Perhaps you would like to discuss anything the TRE brought to your attention regarding trim control when other than in Normal Law.

You must have missed a fairly intense discussion that took place in AF447 Thread No.6 (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-23.html#post6663753), where we were privileged to have some well thought-out input from an experienced aerodynamics engineer.

To directly answer your question, the DFDR traces indicate that even when stalled and with low IAS, any SS ND resulted in the appropriate response.

[RetiredF4]

PJ2: @ TurbineD - a fine post, thanks.

Yes i totally agree, and a good opportunity to close down the A vs B discussions, which are fruitless in the first hand and only turn the exchange of arguments over different technical matters worth looking at into endless distractions from the detailed view itself.

[HazelNuts39]

Interesting aspect of the AF A340 zoom climb is that alphamax is exceeded in normal law.

[rudderrudderrat]

Hi HazelNuts39,
Interesting aspect of the AF A340 zoom climb is that alphamax is exceeded in normal law.
Presumably alpha is measured real time and the airspeed can reduce if delta g is reduced during the apogee. It will take some time for the attitude of the aircraft to change in response to the new alpha measured at 1g, when the speed was so far back.

Some "amazing" recommendations by BEA including:
"The BEA released another safety recommendation to EASA to require the autopilot disconnect aural alarm become continuous until cancelled by human action, reasoning that the A340 cavalry charge by design sounds 1.5 seconds and may therefore be suppressed by a higher priority aural alert. This suppression had contributed to a critical incident, the BEA continued."

Wtfiidn? springs to mind.

[aguadalte]

mm43,
I thank you for driving my attention to that particular part of the forum that I have missed unfortunately.

[DozyWannabe]

Turbine D -

An excellent post, thanks. However I do have to take issue with one aspect:

On the other hand, the A320 Habsheim crash was the result of the pilot going below a 50 ft threshold in which the computers assumed the pilot was trying to land. The plane did exactly what it was suppose to do according to the computers and landed in the treetops.

This is incorrect. Landing mode was never triggered. (The theory that put this forward was in fact advanced by Asseline's lawyers and repeated in the international press).

What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.

In order to do this he did not simply disarm autothrust, he actually disabled it - by holding down the disarm buttons. This makes A/THR unavailable until reset by ground crew (it was in fact intended to be used if A/THR developed a malfunction), and therefore also inhibits alpha floor protection (which is distinct from alpha protection). In order to expedite descent he chopped the thrust back past the point required for the flypast and the engines spooled down, which is a big no-no on approach as I understand it. The descent was expedited a little too much and they went below 100ft RA shortly after crossing the threshold. Landing mode was not triggered - possibly because the RA never held a stable value long enough to do so.

The photocopied aerodrome map did not show the trees at the end of the grass runway because on the original they were a light grey shade below the threshold of the photocopier - they were spotted as a danger about halfway down the runway and the thrust levers were pushed to the TOGA position shortly afterwards. Unfortunately with the engines spooled down and alpha floor disabled with the autothrust as a result of the expedited descent, they took too long to spool back up, and the only remaining protection was alpha protection, which limits pitch attitude to preserve AoA above stall. This, not landing mode, was the reason the aircraft did not climb when Asseline pulled up - he simply did not have the required thrust or airspeed to do so by the time the aircraft was over the trees.

In this case, had Asseline been able to override the computer completely, the aircraft would have stalled short of the trees, crashed out of control and many more would likely have died* as a result. As such, there's a degree of tragic irony that, had the A320 done as Asseline asked, he may not have survived to publicly rubbish the A320 for not doing as he asked.

[* - EDIT : The three deaths that did occur (tragically including two children) were as a result of smoke inhalation, not impact forces - and the injuries were relatively minor, with a few serious cases involving broken bones. ]

[HazelNuts39]

RRR,

The exceedance of Alpha MAX by about 2 degrees during less than 2 seconds occurs in the initial phase of the incident. In the words of BEA (see also the graph):

Phase 1 : dans un premier temps, une rafale de vent de face(1) génère une survitesse et l’activation de l’alarme « OVERSPEED ». Quelques secondes plus tard, une rafale ascendante entraîne une augmentation de l’incidence et de la vitesse verticale. Puis, le PNF déconnecte le pilote automatique et donne un ordre à cabrer pendant 6 s tandis que le PF sort les aérofreins. Dès le début de l’ordre à cabrer, l’incidence étant supérieure à Alpha Prot, la protection grande incidence s’active. Puis, pendant 2 s, l’incidence passe brièvement sous Alpha Prot, avec le manche au neutre, ce qui fait sortir de la protection. Les effets conjoints de la turbulence, de l’action au manche et de la sortie des aérofreins entraînent la prise d’assiette, de vitesse verticale et d’altitude. Un pic d’incidence supérieure à Alpha Prot active de nouveau la protection grande incidence. L’incidence continue d’augmenter et dépasse Alpha MAX, ce qui provoque la rentrée automatique des aérofreins.

(1)Des simulations numériques montrent que la turbulence rencontrée lors de l’évènement se caractérise essentiellement par une rafale de face de 25 kt suivie quelques secondes plus tard par une rafale ascendante de 35 kt. Une deuxième rafale ascendante de 15 kt se produit environ 10 secondes plus tard. La durée totale des turbulences est d’environ une minute. My translation:

At first a headwind gust (see note 1) causes an overspeed and activates the "OVERSPEED" warning. A few seconds later an upward gust causes an increase of AoA and vertical speed. Then the PNF disconnects the AP and makes a nose-up command during 6 seconds while the PF extends the speedbrakes. At the start of the nose-up command the AoA exceeds Alpha Prot and the High AoA protection is activated. Then, during 2 s, the AoA is briefly less than Alpha Prot, with the SS at neutral, which cancels the protection. The combined effects of turbulence, of the SS command and the extension of the speedbrakes lead to an increase of pitch attitude, vertical speed and altitude. A peak of AoA greater than Alpha Prot activates the High AoA Protection again. The AoA continues to increase and exceeds Alpha MAX, which causes the automatic retraction of the speedbrakes.

Note 1: The numerical simulations show that the turbulence encountered in the occurrence is essentially characterized by a headwind gust of 25 kt, followed a few seconds later by a 35 kt upward gust. A second upward gust of 15 kt occurs about 10 seconds later. The total duration of the turbulence is approximately one minute.

P.S. Somewhat mysterious is the continued pitch up with the SS at neutral. One would like to see the elevator trace for that element of the occurrence. An explanation could be the decreasing vertical speed, possibly resulting from a downward gust, and the control system maintaining 1g.

[DozyWannabe]

At first a headwind gust (see note 1) causes an overspeed and activates the "OVERSPEED" warning.

Just to clarify, we're talking about a separate A340 incident here, not the AF447 crash - right?

[Organfreak]

Dozy-- right.
Isn't it, like, about 3 or 4 PM over there? Time to wake up! :)

[DozyWannabe]

Dozy-- right.
Isn't it, like, about 3 or 4 PM over there? Time to wake up! :)

Aye, but I've only been home a short while. I just didn't want another round of misunderstanding, it took a long time to establish that AF447 never went into overspeed.

[RetiredF4]

DW
What happened was that thanks to poor briefing materials provided by AF (they were B&W photocopies, so some shades of grey were either too faint to spot easily and some disappeared altogether - and the briefing notes pointed them at the asphalt runway, not the grass one being used), the crew almost missed the Habsheim airport. To stay on schedule, rather than turn around and make another approach, Capt. Asseline elected to attempt a short final that cut it too fine and maneouvre into position during the descent.

Nothing on the CVR though? Autothrottle disconnect was at 50 feet RA at 12:45:26, 11 seconds later TOGA, 2 seconds later contact with trees.
They :mad: up big time, i live 10 klicks away.

from airbus last pages (http://www.crashdehabsheim.net/Rapport%20Airbus.pdf)

[DozyWannabe]

None of the crew believed they had gone that low - all evidence indicates that they didn't realise they were in any danger until they realised they were level with the trees - as such the CVR was routine up until that point, and quickly became a shouting match as they tried to get out of the corner they'd painted themselves into.

[DozyWannabe]

Below 100', Alpha-prot is disabled.

Alpha floor protection, to be precise (the thrust component). Alpha protection, which is a flight control function and affects pitch and bank, remains active at all times in Normal Law IIRC

The report criticizes planning, coordination and so on.

As it should have. AF's performance as an entity was well below-par that day.

I've often wondered if Asseline would have had a better case if he had gone after AF rather than Airbus - but I suspect that he would not have had the benefit of union backing had he pursued that line.

[RR_NDB]

Hi,

aguadalte

Some time ago you mentioned in an excellent post to CONF iture (*) some points that could clarify an issue:

Why AI (Airbus SAS) introduced the SS?

This issue is being covered in another Thread (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies.html)concerning the "interface". The paper you mention discuss the issue and is a confirmation of some concerns i had previously.

Could you help me to understand why Airbus Industries (Airbus SAS) introduced two separated SS with no feedback in their planes?

There are advantages with this design?

Reasons for AI SS introduction to airliners

Hi,

Why AI (Airbus SAS) introduced the SS? What reason(s)?

It was representative (the visible item) of the Airbus new control philosophy?

What are the main advantages? And it's disadvantages?

What about the overall cost to benefit compared to original (proven) solution?

This interface is adequate when dealing with possible anomalies?

Why active feedback was not built in?

A similar device would be eventually adopted by Airbus SAS competitor(s)?

(http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies-4.html#post7185277)

I mentioned my post in the specific thread avoiding to discuss the issue in AF447 thread. I don't consider the interface an issue between A or B. My agenda is on Aviation Safety, during normal conditions and during anomalies.

PS

The mentioned Thread:

Man-machine interface and anomalies

The increasing technological sophistication in FBW planes brings benefits and challenges to the pilots and other 'players". The objective here is to discuss the "interface" and it´s components, specially when facing anomalies. (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies.html)

(*) CONF iture:
The provocative answer to that question would be: "because Airbuses were designed by engineers but unfortunately flown by pilots"...
My personal guess is that they wanted to brake with the "old" concepts. Starting with a blank sheet, they wanted to show the world that they were able to design an all new aircraft reflecting the European potential for innovation. "An aircraft made against pilot's errors"...
I had the opportunity to meet Pierre Baud, when I was invited to Toulouse in the early ninety's, to fly one of their A330 testbed aircraft. That was my first experience with a FBW aircraft (before that, only Boeing and A310's) and I personally had the chance to verbalize my worries in this regard (no feed-back on SS, added inputs on SS, lack of need for trimming, ATS in step of Auto-Throttles) and he explained to me that this was a new concept of aircraft and that the FBW represented not only an evolution on the handling characteristics but also the chance to save on weight and that the final goal would be MFF and communality.
I do understand that at certain point of the design work, AI engineers had to take options. They have opted for this system and there is no go-back, at this time. It is not yet clear for the majority of the pilot's community that the system is wrong. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-32.html#post7184026)

[Lyman]

There are advantages with this design?


In the development portion of the design, it occurs of course that separated controls were a new direction. The risks were no doubt delineated, assessed and addressed.

There were no downfalls sufficient to eliminate this portion of the design.

Hence, into manufacture, test, and service. What was the benefit portion of the change in approach? Anyone?

A possibility of course, exists that single pilot operation, contingent on the building of an extensive record of safety thus equipped, might be "just around the corner"? Awaiting BEA's opinion on the matter....

On the other hand, it may be that the determination was simply that it was unimportant for the Pilots to "see" the other's controls. Actually, that had to have been one conclusion, perhaps still held?

[RR_NDB]

Hi,

Bear

Commented on "Interface" thread. (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies-4.html#post7185277)

[RR_NDB]

Hi,

DW:

...as they tried to get out of the corner they'd painted themselves into. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-35.html#post7187783)

The corner they entered (ultimately in the trees) was only "painted" by the pilots? Or the designers "preprogrammed" (with the new concept, protected FBW plane) the corner?

Would not be safer to allow a pilot to just exit the corner when absolutely necessary?

Rigid programming (hard limits) is really necessary? The pilots really need this kind of "protection"?

[jcjeant]

When you know the history of AF447 and (as far many saying) formation - training of new pilots it seems that strict limits are needed :}
If they had been strict in AF447 .. Hall could have said in reaction to SS command to climb :
I dunno our speed ... but ..
Your throttles are set at VVV
The weight of the aircraft is XXX
The current altitude is YYY
The temperature is WWW
The CG is located at ZZZ
If you want climb now you're going to put us in a very dangerous situation that's why I will limit your ability to climb
Will give you update ASAP

[CONF iture]

Thanks for that link RF4 :
Habsheim : Airbus Response to the Criticisms to the BEA Final Report (http://www.crashdehabsheim.net/Rapport%20Airbus.pdf)

By any chance, would you have also the document :
L’Affaire/The Case by Mr R.A. Davis which was the main reason of the Airbus response.

To note that Mr R.A. Davis has been at the head of the prestigious AAIB during 15 years, and not only "an aircraft accident consultant" as the Airbus Response likes to describe him. Also, he was specialized in the Flight Recorders decrypting …

Obviously, there is still a tremendous interest for Habsheim.
I just don’t understand why PPRuNe refused me the possibility to start a thread exclusively dedicated to Habsheim … ?

[RR_NDB]

If you want climb now you're going to put us in a very dangerous situation that's why I will limit your ability to climb
(http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-35.html#post7188300)

Why not limit the climb (zoom climb, ballistic climb, any climb) above REC MAX?

Simple programming, easy to inform the crew, hard limit IMHO important to avoid entering a very dangerous space where you could stall and LOC your plane.

Why not? This would be over automation? :=

Simply put:

You must have authority to control your plane. Always. Specially during anomalies of any type.

[jcjeant]

Hi,

Confi_ture
Obviously, there is still a tremendous interest for Habsheim.
I just don’t understand why PPRuNe refused me the possibility to start a thread exclusively dedicated to Habsheim … ?
Sensitive subject !! ... minefield .. contaminated with viruses of conspiracy ... ghosts that lurk .. case closed for justice .... post mortem analysis highly discouraged ... http://smilies.sofrayt.com/%5E/9971/deepsleep.gif

[RR_NDB]

Hi

Sensitive subject !! ... minefield .. contaminated with viruses of conspiracy ... ghosts that lurk .. case closed for justice .... post mortem analysis highly discouraged ...

:}

[DozyWannabe]

To note that Mr R.A. Davis has been at the head of the prestigious AAIB during 15 years, and not only "an aircraft accident consultant" as the Airbus Response likes to describe him.

I've got a lot of time for Ray Davis, and read that he did exemplary work trying to get to the bottom of BEA548 back in 1972 - which was no mean feat given the lack of survivors and lack of a CVR (In fact the recommendations made by his team were what eventually made CVRs mandatory in G-registered transport category aircraft).

Airbus wasn't knocking him, despite how you're trying to frame that statement. They were pointing out that he had been retired for several years before he took the case on. You can't bring a doctor back after an extended period of retirement without first familiarising them with the advances that have happened in their absence - so it goes with accident investigators.

Also, he was specialized in the Flight Recorders decrypting …

No, he wasn't. For a start, Flight Recorder data is not "encrypted", it is encoded. On the old analogue gear this was as a series of voltages and on the newer digital boxes as a serialised sequence of binary data.

Ray Davis was a brilliant investigator, but he didn't really understand how DFDRs differed from their older analogue counterparts, which led him to make several erroneous conclusions about the tapes, which are explained at length in the article Franzl posted.

DW:
The corner they entered (ultimately in the trees) was only "painted" by the pilots? Or the designers "preprogrammed" (with the new concept, protected FBW plane) the corner?

Yes - only painted by the pilots. They diverged from an already shoddily-put together flight plan because they missed the turning point for the airfield, then elected to expedite the descent rather than turn around and start the approach again - letting the engines spool down completely in the process (fatal mistake no.1).

They made the decision to disable A/THR completely to proceed with the display. As PJ2 said, the narrow, short runway may have fooled them into believing they were higher than they were. This prevented any chance that the system could help them out of their predicament (fatal mistake no.2)

Would not be safer to allow a pilot to just exit the corner when absolutely necessary?

In this case, no. I've already said that if Alpha protection had not checked Asseline's attempts to pitch up that the aircraft would have stalled and more would have died.

Rigid programming (hard limits) is really necessary? The pilots really need this kind of "protection"?

Clearly - sometimes - yes. This isn't a criticism of pilots as a breed, just an honest acknowledgment that we all have bad days at the office.

Funny that an allegedly "conveniently buried" issue has already been brought up at least three times in the course of discussing AF447, an incident which bears no relation to AF296 in any way, shape or form on a technical or procedural level.

[RetiredF4]

Confiture
By any chance, would you have also the document :
L’Affaire/The Case by Mr R.A. Davis which was the main reason of the Airbus response.

You are lokking for that one?

Davis (http://www.crashdehabsheim.net/Rapport%20Davis%20(EN).pdf)

Most of the conspiracy stuff is here:

crashdehabsheim (http://www.crashdehabsheim.net/)

[CONF iture]

Thanks a lot RF4 !
The last time I visited that site, a while ago I admit, the original English version of Davis document was not there, only the translated French version was.

You know, nowadays the conspiracy idea is always raised when people are looking to NOT debate a subject - It is getting all too convenient.

I just can't stand anymore reading DozyWannabe uninformed erroneous and false comments on Habsheim.

There is matter to discuss on Habsheim, I'm looking for that.
Of course the level of credibility and independance of the BEA will be chalenged ...

When time permits I will start a thread called Habsheim.

[Lyman]

Distract, Damage, Muffle, Marginalize. The answer is always patience, and some element of good fortune, or a change in fortune of those who hurl "Conspiracy".

The thing I do not get is the animosity toward scepticism.

Patience, Persistence.

The hook in this report will be the conversations, cockpit. Habsheim made a fertile field for loss of reputation, no doubt. Who will guard the guardians? The mere appearance of a conflict should provide a judicial special master, or ombudsman, one would hope. The Public interest is superior to bottom line.

imho

[DozyWannabe]

I just can't stand anymore reading DozyWannabe uninformed erroneous and false comments on Habsheim.

I think you'll find everything I said backed up by the investigators, the courts and and every aviation agency in the world. Your argument is predicated on the paranoia of a mentally ill ex-AF Captain who went to bat with Asseline and ended up ruined.

In the immortal words of Jack Nicholson, "You can't handle the truth".

[Lyman]

Damage, Distraction, Marginalize. Next comes Muffle.

[KBPsen]

Lyman,

Have you considered that people are just fed up with your continued attempts at disinformation and manipulation of the known facts? The picking and choosing, taking things out of context and ignoring others.

The only saving grace would be that you are simply not able understand the subject and/or are a confused soul. I suspect that is only partly the answer.

CONF iture seems to heading down the same path, sadly.

[jcjeant]

Hi,

DW
mentally ill ex-AF Captain Urban legend ...
Sorry DW .. but this Captain was not mentally ill .. and that's not my opinion .. but it is the medical reports that attest after examination by experts that this pilot was not mentally ill
Those reports are available on internet
It surprises me that you did not know that .. saw the interest and knowledge you have of the accident

[Turbine D]

I think you'll find everything I said backed up by the investigators, the courts and and every aviation agency in the world.

I think you are intertwining factual information with personal opinions. Here is why:

Quote:
Originally Posted by CONF iture
To note that Mr R.A. Davis has been at the head of the prestigious AAIB during 15 years, and not only "an aircraft accident consultant" as the Airbus Response likes to describe him.
Your quote
Airbus wasn't knocking him, despite how you're trying to frame that statement. They were pointing out that he had been retired for several years before he took the case on. You can't bring a doctor back after an extended period of retirement without first familiarising them with the advances that have happened in their absence - so it goes with accident investigators.

Nowhere does Airbus point out what is in bold in your statement, that is your interpretation/personal opinion. Mr. Davis challenged the BEA report, particularly that of the recorded data.

IMO, that left both the BEA and Airbus no choice but to discredit Mr. Davis and his technical challenges, and they did. Much was at stake for Airbus, a new airplane, new concept for flight controls, first airplane delivered, a public demonstration and public conjecture that the airplane was at fault. It was important for Airbus to rebut, emphasizing the aircraft performed as designed. In the same way it was important for the BEA to rebut as they were under much heat for a perceived "botched & biased" investigation by the media and others, erroneous or not. This happens all the time in the courts with either the prosecution or the defense attempting to discredit a knowledgable expert witness and it happened in this instance.

Your quote
None of the crew believed they had gone that low - all evidence indicates that they didn't realise they were in any danger until they realised they were level with the trees - as such the CVR was routine up until that point, and quickly became a shouting match as they tried to get out of the corner they'd painted themselves into.


IMO, I don't see a shouting match at all, there were only six short vocal exchanges three by the F/O, three by the Captain once they reached 100 ft., the last comment by the Captain coming while descending into the trees.


Originally posted by RR_NDB
Would not be safer to allow a pilot to just exit the corner when absolutely necessary?
Your quote
In this case, no. I've already said that if Alpha protection had not checked Asseline's attempts to pitch up that the aircraft would have stalled and more would have died.

IMO, the bold in your statement is supposition for something that didn't take place and therefore can't be confirmed one way or another.


Originally posted by RR_NDB:
Rigid programming (hard limits) is really necessary? The pilots really need this kind of "protection"?
Your quote
[Clearly - sometimes - yes.

IMO, this gets back to the philosophical FBW debate, your opinion, not a fact.

Your quote
Funny that an allegedly "conveniently buried" issue has already been brought up at least three times in the course of discussing AF447, an incident which bears no relation to AF296 in any way, shape or form on a technical or procedural level.

IMO, there are always overarching fundamentals, whether they be familiarity with and understanding of the aircraft operating systems, training, improvements and or changes in basic written operational instructions that may differ from one incident to another. Nevertheless, there are relations from this aspect or point of view.

[RR_NDB]

I think you are intertwining factual information with personal opinions. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-36.html#post7189655)

This may be the reason we find sometimes difficult present arguments to DW.

TD probably characterized something useful to be considered by DW and some other participants.

I think it's important to distinguish facts from personal opinions and put both clearly separated.

E.G.

I personally have as a Electronics Designer serious objections against several "resources" (including protections, etc.) used in aviation today. When questions, issues and facts are presented to us it's important to hear, to analyze, to study, etc. before.

Sometimes we must criticize. I made this against the FALSE REDUNDANCY of using 3 Pitot's that stistically fail near simultaneously. I called it ridiculous. The responsibility is not small when we make this. We must check redundantly and then, need to be assertive.

Assertivity without careful analysis is dangerous and can cause problems and confusion.

[PJ2]

DW, re your post #694 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-35.html#post7187816)- "Alpha floor protection, to be precise (the thrust component). Alpha protection, which is a flight control function and affects pitch and bank, remains active at all times in Normal Law IIRC"

Thank goodness I don't have to remember the nitpicky stuff any more. Thirty-five years was enough.

[Lonewolf_50]

For Lyman:
fifty four seconds total of STALLWARN, and not a word......do you think that odd, Lonewolf?

Yes, odd, even though I have seen something very much like that in real life previously*.

I repeat my guess regarding what is behind that non-reaction: SW presumed spurious due to known airspeed spurious input. That said, simply paying more attention to "tasks x, y, and z" may render the audio input less compelling.

*Two (of a number) things I experienced IRL to do with warnings ignored.

A. Late 80's. Night training flght. Safe for solo check, me Instructor, one Student. Standard arrival VMC, night, final landing. Task: simulate "you have an engine oil high temp, low pressure" (engine oil leak drill). Student chooses correct response: climb to high key then set up for a (power on, training) dead stick landing profile. Which he did, except ... (this is at night, warning lights tend to be brighter in the cockpit at night) when he got to high key (~ 2500 feet AGL) he dropped the flaps rather than the gear and began his turn.
This gave him multiple warnings:
Caution light flashing (he'd turned on the landing lights),
flashing red light
loud and annoying warning horn,
He reported to me "three down and locked, landing checklist complete" and proceeded into the turn for low key (which is the abeam / 180 position) for a dead stick landing profile. He reset the Master Caution ... but didn't fix anything else.
I allowed him to continue, figuring he'd catch his configuration error and fix it at the 180. He approaches the 180, calls tower, reports three down and locked (all three indications were up, all warnings still going off) and continues.
Tower clears him to land.
He hits the 90, roughly on profile, (a bit high now, as he should have gear and flaps down already) and reports to me "gear down, flaps down, checklist complete" and begins a gentle slip (a technique taught for altitude control in the dead stick provile) to get his final better matched to profile.
All lights and aural warnings still going off.
I direct him, as he turns to final, to wave off / go around. (IP wants to preclude wheels watch shooting flares at us at night).
I call tower "Wave off, request left Low key" as the student obediently waves off this approach, and tried to raise the gear.
And now, the icing on the clueless cake.
"Sir, the gear handle won't go up, are you holding it down?"
(Instructors would occasionally guard gear handle to avoid certain errors, overspeed gear, etc).

My reply: "You never lowered it, which is why you can't raise it any higher than UP, A---. I have the controls."

I cleaned up the aircraft, took it to low key, performed the rest of the dead stick profile, and landed the aircraft, emphasizing to him the absence of the warning horn, absence of warning lights, and absence of anything odd.

I had flown with him before, and he'd usually gotten things in the right order. I had been his instructor on his first night flight, and he'd flown that same profile correctly then. What struck me was how the warning at night are so much more noticeable, and he never seemed to "see" them.

For whatever reason, he went brain dead and exposed a tendency to report things by rote that he wasn't doing. (Bad idea) No solo for him.

B. Year 2001, me pilot under instruction (referesher training) and my experienced IP has the controls. Day, VFR, return to base for final landing. Pilot enters the break nicely, gets to the 180, calls 3 down and locked (and I check, seeing the handle up and indicators up, and flaps going down) and he calls tower, three down and locked, for landing permission.
I say
"T---, the gear handle is still up, as are the wheels, and that warning horn is kinda loud."
Pause.
Wheels go down, flaps stay down, we review the checklist complete together, agree we have three down, and we land safely. (He buys at the club that afternoon, needless to say. :ok: )

From novice to experienced pilot ... it can happen.

What makes me so confused and so sad is that it seems to have happened to both pilots on the flight deck in AF 447.

That is why I lean toward an internal dialogue inside each head "with airspeed unreliable, stall warning must be spurious."

I could be very wrong, and it may be some other thing, or a bunch of other things.
My take is that the PF was unaware of his climb, and his instruments were not helping him to decide the correct attitude, plus a concern for Overspeed. Another factor could be an uncommanded ascent. Make no mistake, his pull on the stick caused climb, but can we eliminate the a/c climbing on her own?

Altitude display was not known to be manfunctioning, nor the attitude indicator malfunctioning. (Slight unknown, but no strong direct evidence for)
From info reported, PNF's attitude indicator was for sure working.

[HazelNuts39]

If PF didn't notice stall warning, what caused him to select CLB, then TOGA, go to 15 degrees pitch and actively maintain that until the airplane dropped out of his hand after 40 seconds?
http://i.imgur.com/ETUWN.gif?1

[DozyWannabe]

DW
Urban legend ...
Sorry DW .. but this Captain was not mentally ill .. and that's not my opinion .. but it is the medical reports that attest after examination by experts that this pilot was not mentally ill

Norbert Jacquet ended up several lettuces short of an allotment. He paid the "medical experts" (actually university professors) to refute that assertion and then spent the next few years putting together a website filled with ever more paranoid claims that the French aviation industry was out to get him.

As a rule, that suggests a level of paranoia and mental instability considerably above the norm to me. "Here's the reason I was blackballed by my country's aviation industry to protect a dangerous aircraft design, and by the way here are three experts who have all concluded I'm not mad" is not exactly an introduction to inspire one with confidence.

@TurbineD

I wouldn't say I'm threading opinion between documented info - it's pretty obvious that Ray Davis's conclusions come from a lack of understanding regarding digital flight recorder information storage. This isn't me knocking him, this is just a fairly straightforward conclusion. Think what you may of the source, but pages 21-38 (original) of the Airbus rebuttal posted by Franzl go into considerable detail to explain it.

Also worth pointing out is that the BEA and Airbus rebuttals were separate entities and there was no collusion in producing the documents - the BEA invited Airbus to provide their own given the technical expertise on the DFDR technology they were using.

Maybe "shouting match" was an extreme description, but there is a definite increase in volume, intensity and interpersonal conflict from the moment the crew spotted the trees on the CVR.

The "philosophical" debate on FBW and protections aside, I was simply providing an example where the protections *did* in fact save lives from the actions of a captain who on that particular day turned out to not be as infallible as he thought he was.

[CONF iture]

If PF didn't notice stall warning, what caused him to select CLB, then TOGA, go to 15 degrees pitch and actively maintain that until the airplane dropped out of his hand after 40 seconds?
I think it is all about the FDs coming back at that time in V/S mode. The PF happily finds something to follow ...
Before AF447, TOGA was the correct answer to a stall warning, but 15 degrees of pitch was not part of that procedure.

During that period, the autotrim silently helps him to follow that foolish FD command and gives him the illusion to be in control ...

A few elements could now make us think the pilots intentionally discredited the stall warning.


Would you add to your graph the FD, V/S, SEL V/S traces if possible ?

[HazelNuts39]

Would you add to your graph the FD, V/S, SEL V/S traces if possible ? There are some practical difficulties with that, and I don't see the point. On page 111 the V/S Sel equals the V/S and page 91 IR#3 states:
2 h 10 min 47: The FD 1 and 2 become available again (modes HDG/ VS).
The selected heading is 34°.
The vertical speed is 1,500 ft/min.
The thrust levers are moved back to 33° (2/3 of the IDLE / CLB range). The N1 decrease to 85% in 4 seconds.

[Lonewolf_50]

HazelNuts39, your question I don't have a simple answer to.

Caveat: the following is an attempt at analysis, not any sort of "truth" about what happened.

Let's suppose that the stall warning (created by the sustained "zoom climb," which is a matter of either scan breakdown or perhaps an internal decision to use nose to control speed to avoid overspeed ... ) triggered the "low altitude stall warning" response, which might be described and depicted in your graph, albeit with a nose attitude not set and held very well.

1. What stall warning ought to trigger is a decision to reduce angle of attack, particularly when stall warning happens at cruise altitude. It didn't. Why is that? Unknown. (Estimate: In part, I don't think either pilot had a sense of the AoA of the wing. I also wonder at their training regarding "high altitude stall, high altitude approach to stall.")

2. As the warning sustains over time (50-60 seconds) the control inputs do not show a trend of AoA reduction based upon your graph. The overall trend is to climb toward limits of performance envelope (if not into it). What seems to be going on in the cockpit is that the pilot who took the actions you describe is not getting the result he expects.

(Expectation: "If I go to CLB and TOGA, I should fly out of this stall warning.")

Note: his / their response at cruise altitude (with a lower altitude set of procedures) isn't the response one would expect. (Do I hear the Pitch and Power Chorus warming up in the background?)

At some point in that 50 - 60 seconds of response, I conclude a cognitive mismatch:
"What I am doing to treat stall warning is not curing my stall warning sympton."
This could lead to internal conclusion that "A/S is unreliable, this stall warning is unreliable or spurious since what is supposed to fix it didn't."
Further stall warnings, when they come back on well into the stall, are ignored during the period when a potential remedy (nose down, fly out of the stall, begun somewhere above ~ 12-15000 feet?) to stall could be attempted.
The signal "stall warning" is never converted into either pilot's awareness "you are stalled" realization. I believe that if PNF had diagnosed "we are stalled" he would have said so to the PF.
(From my example, my flight student never converted "lights and warning noise" to "your gear are still up" realization.)

Back to AoA, which is measured but not displayed. There is no AoA gage to consult as a cross check. Neither pilot seems to have considered digging down through the pages to get a look at AoA. (Memory hazy: is it seven button / page actions to get there? PNF would need to do this, PF was behind the aircraft and trying to fly it). Given their task loading gradient and apparent misunderstanding of what is going on, I am not surprised that PNF didn't go head down in search of AoA on the pages. Were AoA a primary concern, the actions we see evidence of on the traces would probably have been different. Also, when captain at last arrives, would his glance at an AoA gage help him say "{Merde!} You are stalled, do x, y, z, etc." Don't know, maybe yes.

So there you go: if not initially (your point is taken on that score), then at some point subsequent, the stall warning was either
dismissed as suprious
or
ignored due to "what is it doing now?" problem solving/confusion overriding aural cues.

@ 0210, 47 sec.
The thrust levers are moved back to 33° (2/3 of the IDLE / CLB range). The N1 decrease to 85% in 4 seconds.
That appears, from your graph, to be about six seconds before CLB TOGA are chosen. Did I read your graph correctly?

[Lyman]

HazelNuts39

In your graph, notice stick placement when "Pulled". The UP inputs are spikes, between them are lapses of linger in Nose Down.

It appears that his UP inputs are a severe reaction to something about the a/c behaviour. Quickly, after pulling up, he immediately reverses and pitches down; the stick does not remain in NU? What might be the cause of this actions? What is he getting from ND that he does not "like"?

Or Lonewolf?

[Lonewolf_50]

It appears that his UP inputs are a severe reaction to something about the a/c behaviour.
Lyman, this is a guess response based upon a few things.

1. Stated sensitivity of this model acft at high altitudes by people who have flown it, as compared to control sensitivity in the terminal area and altitudes.
2. Change in power setting
3. Pilots initial overcontrol of roll previous to the graph

The above considered, what HN's graph excerpt shows me is that as with roll, the PF doesn't have a good "feel" for his pitch control during seconds 50-85, so there's a bit of over controlling going on. Part of what he's doing looks to me like a response to a pitch change that you'd expect from an addition of power to TOGA, and in part to correct for his own various pitch inputs, corrections, and counter corrections that he apparently isn't happy with. Why unhappy? I think he's aming for a particular pitch attitude and not hitting nor holding it. (Could be wrong).

I am uncertain what pitch attitude he is trying to establish and hold.

From 90-100 seconds, he makes what appears to be a substantial counter correction in the nose down direction with very small counter corrections ... he's milking the stick a bit, trying to avoid overcorrection during that phase, and seems to be making progress in establishing his "feel".

Not sure where the CVR sync's up, but I suspect this particular correction is a response to PNF's warning about 'you are climbing' and 'go down'

Not sure what other forces you are referring to. Seconds 120 to the end, he appears to be deliberately walking the nose down. The graph ends in what appears to me to be the next set of corrections / counter corrections about to start ... though why the SS at - angle induces nose up at the tail end there confuses me ... seeing the whole timeline/graph would probably resolve that confusion.

[Lyman]

Around the time Captain re-enters, PNF takes control and inputs full left bank. So it seems that both pilots are acting with "Full Stick" ?

HazelNuts, I think I said PF was unaware of his climb, not the Stall Warn.

Lonewolf, not wanting to belabor it, but the graph above null is more reactionary than that below,,,,, it seems to ape the ROLL oscillations, but in PITCH.

The "UP" is spikes, the ND, more flat. So, he's lingering in ND, and spiking NU?

??

[HazelNuts39]

The zoom climb is not 'sustained'. In response to the PNF's "go down", the V/S is reduced from 7000 fpm at t=25s to 1100 fpm at t=49.

As I read his SS movement, he is trying to maintain 15° pitch but is overcontrolling, like he was earlier in roll. Each time the pitch increases through 15° his SS moves forward, and backwards again when pitch reduces through 15°. From 90-100 seconds, he says "I've lost control ..." and goes all the way to full nose-up to counter the nose-down pitch rate.

[Owain Glyndwr]

Lyman

The "UP" is spikes, the ND, more flat. So, he's lingering in ND, and spiking NU?

I think you've got it about face again - +ve sidestick is ND - he's lingering in NU.
Check the DFDR traces for SS sign convention

[DozyWannabe]

I think you've got it about face again - +ve sidestick is ND - he's lingering in NU.

Correct.

For what it's worth, I think he's chasing something on the ADI rather than the FD (although we'd need confirmation of what the FD would output in that circumstance to confirm or refute).

[Lyman]

Dozy, Owain. Thanks for the correction. And thanks to HazelNuts39 for his establishment of a rationale in re: PF manual control of the a/c. Something is preventing his establishment of 15 degree Pitch NU, such that he must emphatically get the Nose down? Either way, the spikes to me are a sign of problems in Pitch, just as there were in Roll.

Can we entertain a chronic bias NU, similar to that seen in Right Roll? From the bank traces, just as here with Pitch, there appears (to me), to be just such a bias. Can we conclusively say that the a/c was unbiased in Pitch? Not to include the THS, at least at this point?

Thanks

[HazelNuts39]

Lyman,
I think we can conclusively say that the a/c was unbiased in Pitch and in Roll.

[rudderrudderrat]

Hi Lyman,
Can we conclusively say that the a/c was unbiased in Pitch?I'd say the aircraft naturally wanted to lower it's nose as the speed washed off.
It was only due to the PF's mostly nose up ss demands, aided by full nose up stab trim, that he managed to prevent it from lowering.

[CONF iture]

There are some practical difficulties with that, and I don't see the point.
The point is precisely to emit a logical hypothesis to your earlier question :
"If PF didn't notice stall warning, what caused him to select CLB, then TOGA, go to 15 degrees pitch and actively maintain that until the airplane dropped out of his hand after 40 seconds?"
If the V/S was at 1500 ft/min at the time the FDs reappeared, then the SEL V/S target reopened at that 1500 ft/min. But as the V/S soon was in reduction, the vertical command bar went up, and the PF was proceeding to follow the command and the trim was 'helping' him to do so.

To note that under stall warning the FDs were telling the pilots to pull ...

[Owain Glyndwr]

I'd say the aircraft naturally wanted to lower it's nose as the speed washed off.
It was only due to the PF's mostly nose up ss demands, aided by full nose up stab trim, that he managed to prevent it from lowering.

I'd say that he held it up there deliberately, but that's only nitpicking :D

I don't want to spoil the fun, but Clandestino was right when he cautioned against applying 'normal' rules to the stalled state (post #221). I think maybe you can apply some generalisations,i.e behaviour averaged over many seconds, but when you get down to specific time slots there are just too many unknowns.

Just for example; we know that stalling AoA depends on sideslip, so that pitch behaviour near the stall will also vary with slip. We know that the sideslip at high AoA varies kinematically with bank angle, as does AoA itself, so AoA, pitch and sideslip are linked to roll, and we know that the natural lateral behaviour at high AoA is a virtually undamped roll oscillation so that one can expect a sympathetic oscillation in the longitudinal axis. How the dickens can one unscramble that lot without access to some very good data and a powerful computer or simulator? And that is without considering any known possible effects from forebody vortex shedding or wingtip vortex movement over the wing or vortex bursting.

IMHO It just ain't possible - you are wasting your timehttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/puppy_dog_eyes.gif

[Lyman]

Thank you both. It may be obvious, I am trying to look at all the inputs, to find something, a clue, as to why: Stall. One needn't remind of the way it looks as a whole. His spike ND looks almost desperate, even angry. So what I seek is an opinion as to why these emphatic ND's? It is in this region of the accident that CRM seems conspicuously absent. If Someone could explain, for instance, why rather than the jerky motions, PF didn't settle on a nudge/ wait format. The aircraft in Pitch cannot move as his stick would, and since the trace of actual Pitch is far smoother than the inputs that command it, why the constant oscillation in stick/hand?

At the least, is it fair to think that the controls and procedures are more reflective of down low, than up high? From the stick trace, the ND inputs seem solitary, again, as if he is angry perhaps at his own over-control? An unfamiliar response from the a.c?

[Lonewolf_50]

HazelNuts39
The zoom climb is not 'sustained'. In response to the PNF's "go down", the V/S is reduced from 7000 fpm at t=25s to 1100 fpm at t=49.

OK, I am working on just this bit of the graph.
From time = 0 to time = 25, zoom climb took x seconds.
As I understand it, that was due to more than a single input to the SS.
Am I wrong about that?
It is my understanding that he sustained the climb, but am happy to be corrected.

We enter your graph excerpt at time = 50, after the PNF has alerted him to climb. He's still climbing (sustains his climb), altitude increasing (until stall, and then until momentum peters out).
For this excerpt of the graph, "zoom" climb probably wasn't an apt description. Thanks for that. :)

By your graph, at time = 105 to about time = 115, he lowers, and keeps lowered, the nose ... or is that the aircraft doing it for him? (See rudderrat's comment). He's moving the SS to get the nose down, or so it seems from the lines. (Even though he says he's lost control, which apparently he has not, at least not in pitch)

As displayed on the graph, his pitch corrections follow the SS graph, out of phase or delayed by a few seconds as the plane takes X amount of time to respond. This ain't an F-16, eh? (Where's gums? :))
As I read his SS movement, he is trying to maintain 15° pitch but is overcontrolling, like he was earlier in roll. Each time the pitch increases through 15° his SS moves forward, and backwards again when pitch reduces through 15°.
OK, I see where you get that, thanks. Strengthens the idea that he's executing the low altitude shaker stall avoidance procedure.
From 90-100 seconds, he says "I've lost control ..." and goes all the way to full nose-up to counter the nose-down pitch rate.
And then starts walking the SS down, 90-100 seconds, orange line.
And the nose follows.

rudderrat:
I'd say the aircraft naturally wanted to lower it's nose as the speed washed off. It was only due to the PF's mostly nose up ss demands, aided by full nose up stab trim, that he managed to prevent it from lowering.
Thanks! That paints a slightly different picture for me, and makes aerodynamic sense.

[Owain Glyndwr]

By your graph, at time = 105 to about time = 115, he lowers, and keeps lowered, the nose ... or is that the aircraft doing it for him?

Wasn't that the time he throttled back to idle? (not shown on HN39's graph)

[HazelNuts39]

Owain G,
Yes, that is correct. Reading from the graph on page 113, the thrust levers are moved to MCT at t=103, then to idle at about t=107, then at t=128, when the engines have spooled down to near-idle rpm, thrust levers back to CLB, and at t=153 to TOGA.

[Lonewolf_50]

HN39, thanks. As usual, it isn't just stick/yoke that influences attitude.

We return you to your regularly scheduled program, which today is a live performance of The Pitch and Power Chorus singing their cover of REM's Feeling Gravity's Pull.


...
What the hell is it doing now, ami?
Pitch and power and out of synch here
Pull up, pull up, pull up the sky is open-armed
When the nose stays up, I feel gravity's pull
...

With apologies to Buck, Stipe, Mills, et al ...

[A33Zab]

2 h 10 min 47: The FD 1 and 2 become available again (modes HDG/ VS).
The selected heading is 34°.
The vertical speed is 1,500 ft/min.
The thrust levers are moved back to 33° (2/3 of the IDLE / CLB range). The N1 decrease to 85% in 4 seconds.


@2 h 10 min 47: Selected V/S equals V/S ~ 1500ft/min as CONF correctly stated.

The first 10s the FD bars will be flashing, just before STALL it would have been steady.
During the STALL (negative V/S) the FD order would have been SS UP (in reference to +1500ft/min), Max Guidance is hard limited at 6000ft/min.

However, soft limits are build in and that will make it difficult to determine the exact FD Pitch Bar position.

- FD bar order will never guide into Vmo/Mmo or below VLS (VLS-5 if VLS = target)
was VLS available? and if so was airspeed already below VLS? and if so will it guide to reach VLS?

FCOM section 1.21.00 states:



Note :
When flying with FD bars only (AP OFF), the FMGS adjusts the pitch bar so that VLS is maintained.

However, no triple click is generated and the V/S target display on the FMA remains unchanged.

[bubbers44]

No pilot would use FD command bars in a situation like this unless they were right out of FO school. Experienced pilots do what they have to and ignore FD commands doing what they are trained to do. Everybody knows that.

[Lyman]

was VLS available? and if so was airspeed already below VLS? and if so will it guide to reach VLS?. From...above, @ A33Zab

Isn't that dependent on ADR's? HazelNuts?

Weren't FD selected to acquire FPV?

[OK465]

b44:

Any chance of you coming out of retirement?

I'm a big fan of people who know what they're talking about...as a result, from here on in, without you, I'm taking Amtrak, Greyhound or some Italian cruise line.

[bubbers44]

OK465, Thanks, because I thought I would get beat up on my post. We old timers used a FD as a guide if it was going where we wanted to go. If not just disregard and go the way you want to go. Worked fine for years. Pretend you are a 727 and fly as you want, it works great.

I even did it with a check airman out of SJO in a 757 on my initial international captain check. He had it so screwed up after our new clearance I was in a 30 degree right climbing turn and he was in a descending dive on the FD. I ignored it and eventually he caught up. I did it right, he was trying to make automation do it.

[CONF iture]

FD bar order will never guide into Vmo/Mmo or below VLS (VLS-5 if VLS = target)
was VLS available? and if so was airspeed already below VLS? and if so will it guide to reach VLS?
Interesting.

For the FDs to reappear, if I am correct, they need 2 airspeed indications in agreement. As both recorded airspeed indications were different, probably the unrecorded one was in agreement with one of the recorded. At that time, both recorded airspeeds were below VLS, one slightly above 200, the other one around 100, and the VLS was around 240 if I get it right from the QRH.

Now, the automatic speed protection you mention applies if VLS is approached from above, but would it apply if the airspeed is already and suddenly well below VLS ?

Also, such automatic speed protection applies for a climb scenario. Would the FDs command a temporary descent in order to get back to VLS ?

[A33Zab]

Correct, FD needs 2 airspeeds. (FE for speedtargets calculations only 1)

@ 02:10:42 FD was transitonary available; IMO ADR2 was increasing and crossing the ADR 3 airspeed (~transitonary).
@ 02:10:47 it was consistent with ADR1 and FD returned.

I interpolated Vs1G (205t, FL350) ~ 185kts, VLS = 1.23Vs1g ~ 225kts.
anyway both airspeeds below VLS.

BEA didn't have an answer in IR#3 either:


4.3 Recommendations relating to Flight Recorders

Analysis of the FDR parameters and audition of the CVR provide
information that is essential to an understanding of the event.
However, it is difficult to reconstruct the indications that were available to
the crew on their instrument panel, especially the instructions given by
the Flight Director crossbars when they reappear.


They will know about now!

The latest FCPC mod 2K?* / software may be a result of this.

Ref. AD 2011-0199R1 (http://ad.easa.europa.eu/ad/2011-0199R1) and AD2010-0271 (http://ad.easa.europa.eu/ad/2010-0271)

[HazelNuts39]

anyway both airspeeds below VLSAgreed.

Sorry for nitpicking, but just to ensure that we work from the same basis:
At 02:10:49 ISIS altitude= 37500 ft, ADR1 airspeed=216 kCAS, M= 0.68. Then Vs1g=200 kCAS and Vls=1.23 Vs1g= 246 kCAS.

[A33Zab]

Not considered as nitpicking, thx for rectifying my wrong interpolation.

246kts accepted as VLS....

[DozyWannabe]

Thank goodness I don't have to remember the nitpicky stuff any more. Thirty-five years was enough.

Sorry PJ2 - it's just that having been told I'm misinformed and know nothing of the protections, I felt we'd better make things as exact as possible!

[OK465]

Now, the automatic speed protection you mention applies if VLS is approached from above, but would it apply if the airspeed is already and suddenly well below VLS ?

Also, such automatic speed protection applies for a climb scenario. Would the FDs command a temporary descent in order to get back to VLS ?


CONF: This is as you say definitely interesting.

The specific failure mode that put you into alternate law will determine whether VLS is computed and displayed or not.

From simulations (using manual deselection & reselection of the FD's), if the failure mode does not preclude computation and display of VLS on the PFD with an operative FD then the following appears to apply:

1. If above VLS and decelerating when the FD's are reselected, the FMA vertical mode will default to VS and display the current VS and the FD pitch bar will command that specific VS (i.e. +1500) until such time that VLS is reached and then command nose down (decrease in pitch) to honor VLS. The FMA annuciation will remain VS with the displayed command (i.e. +1500) that was in effect when the FD was reselected even though the pitch bar is honoring VLS.

2. If below VLS when the FD's are reselected, and VLS computations available, the pitch bar will immediately command nose down (decrease in pitch) to honor VLS, but the FMA will still default to VS and display the specific rate in effect at the time the FD's were reselected (i.e. +400, etc.)

***************************************

If the failure mode responsible for alternate law precludes computation and display of VLS (i.e. VSW only zipper with flap position sensor problems and VLS dashes on the PERF page), then the following appears to apply:

1. Regardless of whether above or below the actual but uncomputed and undisplayed VLS, when the FD is reselected, the system will default to VS and the current rate (i.e. +1500) and the pitch bar will command that rate right into the stall, if followed.

*******************************************

I would guess that recovery from actual dual or triple ADR problems that result in 'latched' ALT 2 would result in no VLS computation or display but I'm not positive. Maybe you or A33Zab would know.

Simulations that allow for dual or triple ADR failure are directed at the failure remaining in effect until landing so that if the ADR's are 'revived' the aircraft returns to normal, not latched ALT 2.

Possibly a new simulation requirement? I'm always in the market for good tech info. :)

[Lyman]

"Also, such automatic speed protection applies for a climb scenario. Would the FDs command a temporary descent in order to get back to VLS ?"....

tantalizing.....

I see "Zipper" (5000fpm descent), " FD commanded descent" (PF's pull to defeat), and FD commanded ascent......

What does this mean to a layman?

[OK465]

Lyman/Layman:

With A/P disengaged, FD's do not cause the aircraft to 'do' anything, don't require 'defeating', and should be deselected when unreliable.

Different 'zipper'. :)

[DozyWannabe]

More to the point, after a UAS/autopilot disconnect incident the priority should be to just keep the thing stable. In cruise the FD, being a visual guide as to how autoflight would follow the FMS programming, is only really useful for navigation and to a lesser degree maintaining flight level. Like autopilot, the FD cannot aid a recovery.

In short, Aviate, Navigate, Communicate - in that order. The FD only really applies to the second of these.