AF 447 Thread No. 5 [Archive] - Page 7

takata

4th Aug 2011, 10:21

Hi vanHorck,
Glad to notice from the English translation of BEA they concur with my explanation of the French, in that the correct translation of the CDB at 2:12:15 is:
There I don't know
There it is going down
As two distinct sentences, obviously pointing at two different instruments.
Congrats vanHorck! your French is better than mine and I noticed that as well (in fact the first thing I looked at!)
All the ambiguous sentences are translated the exact same way a non French native (but anglophone) would have interpreted them. Note also that ambiguousness is more than one meaning, not that any other interpretation is forcibly the bad one. The fact is that we don't know more than the original text but I still doubt seriously of several "interpretations" from the English report... Zut! They were speaking French, not English!

Hence, there is no evidence either that BEA members really cared about this work, after having already released the French text without meaningful punctuation or context helpers (moreover, they are covered by their note: French texte is reference)... they might have subcontracted this translation work.

For example: do you really think that a BEA member would not catch a few things:
- Sal-Amilcar in Heading Verde ... for Cape Verde (Cap Vert)

Or translate :
- the wings to flat horizon the standby horizon (what does it mean, seriously!?)
- no it won’t (not)... not not!
- No above all don’t extend (the) ... extend "the" what?
- er no we’re in computed ... but not in manual mode!

Would you usually call the rudder controls a rudder bar?, spoilers/speedbrakes, airbrakes?
Remember what I expected from this translation: not a single clue added but certainly more errors.
:rolleyes:

JD-EE

4th Aug 2011, 10:31

JD-EE

4th Aug 2011, 10:46

JD-EE

4th Aug 2011, 10:58

Franzl, I've never put a single person from a single forum of which I am a member on ignore list in my life! I'm quite capable of mentally filtering out waffle if I need to, and I've always operated under the assumption that even people who get on my nerves probably have something to teach me, so it would be ignorant of me to ignore them. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

That is EXACTLY why I have not filtered out some of the more irritating posters here. They have experience I do not have. And the annoyance is more at their going way out on a limb, sawing away at it, and then jumping up and down to break the limb off. That sawing and jumping part gets on my nerves.

The out of the box thinking is sometimes helpful if it's dropped once it's seen as nonsense.

takata

4th Aug 2011, 11:01

I think I can see now which stick it is, but why is there no 'Dual Input' warning at "2 h 12 min 59" onwards?
There is? later. It is not systematic: this warning is triggered if imputs are not in the same way, if one pilot don't use priority (disabling other imputs)

I also note (must have been asleep!) that the report says there " The pitch attitude varies from 11° to 13°." Do they really mean that? If the minimum attitude was 11 degrees that is extremely high for level cruise to start the manoeuvre.
Still asleep?:)
Increase up to 11° (started from 0°) during the sequence 0210:07 -10:18, pitch was low at the begining (likely due to thrust reduction)

Here is the whole (English) extract for those 7 seconds.
Those are the next 7 seconds after my quote above for 0210:18 -10:25.
Manoeuver started at 0210:07, not 11 seconds later.

RE The spoilers, I am having difficulty looking at the 'LH/RH' 1-6 lines which mean nothing to me, but there is no mention in the CVR extract of speedbrake retraction, only they are 'deployed' at "2 h 12 min 04 - 2 h 12 min 07" - is that Spoiler LH/RH3 as shown in red? Is the other (LH5) triggered by aileron input?
Look at straight orange curves: "Spoiler LH6", see both "V" at exact same time: released, retracted. It took less than 10 seconds.

takata

4th Aug 2011, 11:08

Hi A33Zab,
Can anyone explain this?
Yes. the green curve represents the "selected" altitude recorded by flight Guidance. Each time the FD disengage and re-engage, it will take the current FL as the new value for "selected".... and FD disengages a lot during the first minute!
There is no impact on flight controls without AP. There is also another graph with Mach "selected", same thing.
PJ2 already explained that a few dozen pages ago!
:)

JD-EE

4th Aug 2011, 11:11

Shadoko, if I had to guess I'd suggest there was an analog to digital converter in the picture that saturated and went past saturation. Some specific types will peg and stay there. Others will wrap their N bit counter and start over at zero. It looks like the plane had the latter sort.

takata

4th Aug 2011, 11:31

Hi JD_EE,
The plane quit doing what he asked for. It went nose down, and stay there depressingly long, when he had full up on the elevator.

(And it was Takata, bless his heart, who pointed me to this in one of his messages in the last few days here on these pages.
Thanks sweety!
But you should also remember that I had likely found an explanation for the first drop of the nose... not in pilot's flight control imputs!

You'll have to look closely at the thrust settings to see it. This drop happened exactly when they reduced thrust from CLB down to IDLE (hence, the following large pitch down moment) and it certainly also caused the right wing to depart at the same time... consequentrly, it caused twice the amount of confusion as the PF tried desperately to keep his wings level and his nose up at the same time.

Captain watched it, arriving at the same time. During most of the following minute, aircraft pitch was maintained up and down between -10 and +10.... but they re-applied full thrust again... really too bad. If they had stopped their pitch imputs and let the thrust to IDLE, simply controling the turn, she might have recovered naturally at this point.

vanHorck

4th Aug 2011, 11:37

Hi Takata,

We read from the same page! :ok:

The Brothers of the Christian Church in Thonon Les Bains boarding school at least taught me reasonable French, that's the only good thing to say about my education there......:ugh:

I think reading the French original in combination with the BEA translation at least gives us some indication of what actually went on in combination with the BEA interpretation.

In all I am not a conspiracy theorist and I am impressed with their Diligence so far

DozyWannabe

4th Aug 2011, 13:05

DozyWannabee, do you see an anti-correlation? He asks for nose up and gets a very significant nose down. When that happens, what does he think? Does his entire mental process derail, especially if he does not recognize he is stalled?

I don't and can't know what he thought, because he's dead. But to my mind only two things can make apparently undamaged controls fail to respond in the correct manner, and those things are:

an overspeed into the transonic region
a fully-developed aerodynamic stall

It would appear that the PF - initially, at least - believed it was the former, when in fact it was the latter.

HazelNuts39

4th Aug 2011, 13:06

Hi A33Zab,
Quote:
Originally Posted by A33Zab
Can anyone explain this?

Yes. the green curve represents the "selected" altitude recorded by flight Guidance. Each time the FD disengage and re-engage, it will take the current FL as the new value for "selected".... and FD disengages a lot during the first minute!

Hi takata,
With reference to this question and your reply, how do you explain (on page 112 of the french report, also on page 113) the cycling of 'Mach selecté' between 02:00:00 and 02:09:55? Is this Mach_1, Mach_2 or Mach_3?

3holelover

4th Aug 2011, 13:08

Small planes don't stall that way, do they?
Sure, they can. with some (Cessna 150 for example), If you hold back elevator, with a bit of energy, it'll lift the nose to stall, drop the nose and repeat... On the other hand (or with another bird - 172 for eg.), if one gradually enters the stall and retains up elevator you can get the bird to mush all the way down without ever un-stalling the wings. ...The attitude during the "mush" will depend on the bird of course... The tricky bit is keeping the wings level to avoid a spin. ...and on the little birds, use of rudder is the only way to accomplish that. Any aileron input, once stalled, is more likely to induce a spin. (I've also played with that quite a bit with little RC airplanes - I have a little bi-plane that will quite happily adopt a 5-10 degree nose down, 60-70 degree FPA when held in the stall)

When I learned to fly, novice pilots were introduced to these variations of stall during initial training. I guess it might have taken quite a bit of training to get a professional pilot to unlearn stall characteristics, somehow. :confused:

rudderrudderrat

4th Aug 2011, 13:27

I guess it might have taken quite a bit of training to get a professional pilot to unlearn stall characteristics, somehow.

I realise it may seem that way - but AB FBW in ALT LAW feels like nothing else you've ever stalled.

3holelover

4th Aug 2011, 13:36

I can only imagine RudderRudderRat... but can it's stall really feel like an overspeed?

SaturnV

4th Aug 2011, 13:37

takata

4th Aug 2011, 14:09

Hi HN39,

With reference to this question and your reply, how do you explain (on page 112 of the french report, also on page 113) the cycling of 'Mach selecté' between 02:00:00 and 02:09:55? Is this Mach_1, Mach_2 or Mach_3?
None as it is unrelated to ADR Machs.
Mach "selecté" or "selected Mach" is entered manually by the pilot in "selected" mode or managed by the FMA in "managed mode". Of course, one needs an autopilot working in order to use the flight guidance.
Consequently, this graph value represents the "Mach" targeted currently selected/used before autopilot kicked off.
Last change was at 0209:58 when "managed" mode was switched to "selected" mode, and pilots set it at Mach 0.80 (they were reducing targeted Mach). So before this point, Mach variations should have been automatically managed.

Looking at graphs pages 112-113, Mach_selecté is the blue straight line at M.80 (barely visible on the second one). The green value should be ADR_Mach_1 (as there is no ISIS_Mach). The blue blocks should be periods of flight in managed_Mach.
Mach_selecté do not move at all during the event like altitude_selectée ; the last one was rather the active mode (vertical)... hence, maybe this "je te mets sur ATT" would rather be "je te mets sur ALT".
But I'm not sure, I need to verify this last point.

GarageYears

4th Aug 2011, 14:13

3holelover:
I can only imagine RudderRudderRat... but can it's stall really feel like an overspeed?

How about:

Can it's stall really SOUND like an overspeed?

3holelover

4th Aug 2011, 14:37

GarageYears

4th Aug 2011, 14:59

Page 108 English version:

Why is the Capt sidestick shown as INOP from 2:14:20?

Did the FO side priority switch get pressed?

Or am I misunderstanding?

takata

4th Aug 2011, 15:13

Page 108 English version:
Why is the Capt sidestick shown as INOP from 2:14:20?
Did the FO side priority switch get pressed?
Or am I misunderstanding?
You are not mistaken at all. PF disabled PNF stick, using priority, during the last 10 seconds or so. Note that the last imputs from the PNF reverted also to nose down. The vast majority of his few imputs were ND anyway.

bratschewurst

4th Aug 2011, 15:23

"Can it's stall really SOUND like an overspeed? ... If it did, that could certainly explain the confusion on the part of both the PNF and the Captain, but the PF?.... I have difficulty understanding how he could have interpreted motions and responses to his inputs as an overspeed vs a stall. ...even if it did sound that way. In an aircraft with unpowered controls, the pilot gets important tactile feedback re airspeed from how much force is required to move the controls. I doubt that an experienced Cessna pilot, for example, would mistake a stall for exceeding Vne in a light aircraft, even in the absence of external references or air data.

Obviously that's missing from this aircraft, although that begs the question of how control "feel" could be correctly added in the absence of reliable airspeed. Presumably Boeing has such an algorithm; whether or not it would have worked in this situation is beyond my ken.

But it does go to the problem of how far the pilot is separated from flying the airplane (as opposed to flying the computers) in 4th generation air transport aircraft.

NARVAL

4th Aug 2011, 15:36

Thank you Takata for your expanation about the flight directors.
I have been as all of us, appaled by the entire sequence of events.
I firmly beleive (and it has been said elsewhere) that the trim wheel and the THS staying at 13° until the crash is the key explanation to their not regaining control of the aircraft, but I keep wondering about the FD's. As you said, when reengaging, they take the altitude of the time as their new reference, and the horizontal bar will (with the plane diving down ) give an UP order to the pilot, who is trained to follow it.
They(the FDs) should have been switched off on both sides from the very moment when the loss of valid airspeed indications became clear to the pilots : emergency procedure on page 81.
Strangely (to me…they must have a good reason !) Airbus does not ask for the Fds to be switched off in their procedure « Stall Alarm » (page 64) when asking to set ,with TOGA, an attitude of 12.5 degrees (taking off) or 5 at altitude. In those cases, a different order by the horizontal bar could be misleading and unhelpful or confusing.
In fact they (the Fds) were not cut off, so the bars on the displays kept coming on, then off, and one wonders if the horizontal bar, which one is trained to following, was not one of the reasons the flying pilot kept pulling upwards ?

xcitation

4th Aug 2011, 15:45

xcitation, might a 10 degree nose down attitude give them a rather distinct impression they are in a dive, even after asking for full nose up? He asked for nose up. Nothing happened. He asked for more nose up. Nothing happened. He kept this up to hauling back on the stick all it would go. THEN the plane goes nose DOWN 10 degrees over a few seconds?

I suppose if he'd ever been properly trained about stalls in A330s he might have recognized "the real thing" and not a warning. Perhaps if he'd had a real AoA report to look at he might have recognized "the real deal" and not a mere warning.

The plane quit doing what he asked for. It went nose down, and stay there depressingly long, when he had full up on the elevator.

I think at that point they were in a total state of confusion which would challenge even the best Ace. I have slightly modified my view on the overspeed.
Consider the start when AP disconnect the PF made aggressive nose up. After only 4 secs stall warning comes on. He reduces his nose up a bit however continues his ascent to FL375. By that point he is in a nightmare having traded his velocity energy for altitude potential energy.

Why did PF nose up initially? It was accidental. No verbal announcement, no increase in thrust etc. At that it appears there is no reason for a climb. Only AP disconnect and speeds becoming invalid. No indication of overspeed or stall until 4 seconds into his aggressive zoom climb manouver.
If you look at PF verbal transcript he sounds IMHO like he is in shock. It takes him a long time to even acknowledge the climb despite PNF nagging him 3 times to get back down. IMHO he is not aware of his own stick input from the onset. IMHO he is in the medical terminology "altered" i.e. mentally impared perhaps due to shock. Epinephrine surge can do strange things to the body, cold sweat, tense muscle, max heart rate and max respiration, blood draws to core and you can look pale. If you have been in this state you know how it feels and it's not good. By contrast the PNF appears to be much more collected and even frustrated by PF lack of response.

GerardC

4th Aug 2011, 15:55

At that it appears there is no reason for a climb What about loosing instantly 300 feet when IAS quit (speed related altimeter correction) ?

bearfoil

4th Aug 2011, 16:09

With respect, PJ2 is precisely on point. However, the focus of the investigation seems to be closing on Human Factors, and rightly so, if the Data released is accurate.

If this is too quick, then my apologies. The CVR shows at its very basic a lack of underdstanding of the Flight Path, and its stimuli, both human, and mechanical, (Electrical?).

The Human dynamic will eventually be broken down by Psychologists, Behavioural, Physiological, and probably Psychiatric. This seemingly dysfunctional mess after loss of Autoflight will be dissected, and rightly so.

First, and not least, is the SS. The SS is only lacking in 'performance' relative to its Human counterpart. There is no need for each Pilot to see his counterpart's stick, period. Not if CRM, and a strictly no nonsense environment is followed. That is how I see it. Does PJ2 agree?

rudderrudderrat

4th Aug 2011, 16:23

Hi PJ2,
The pilot is no more separated from his aircraft because it is wire-control than he is under hydraulic control.
I disagree.
AB FBW Normal Law feels completely different to any conventional aircraft I've flow. (VC9, 707, 737, TriStar, 747-400).
Occasionally, I am still tempted to "pick up the wing drop" on the approach in gusty conditions. Unfortunately the FBW decides to pick up the wing itself and the roll rate is now faster than I wanted. Hence PIO.
The PF was handling Roll Direct in ALT LAW which he obviously found very difficult (from the recorded inputs). Meanwhile Pitch ALT Law is unknowingly trimming out the elevator load with the PF's errors in back stick commands. (They have lost the natural speed stability of the aircraft).

No conventional aircraft feels anything like AB FBW in ALT LAW.

Hi Bear
There is no need for each Pilot to see his counterpart's stick True if the trajectory is what you want. If it's not - then you have no idea if it's PF's inputs or CB activity throwing you around.

gums

4th Aug 2011, 16:34

For the subsonic wing shape you can "feel" buffet and "stiffening" of the stick at the critical mach, whether via artificial control stick mechanisms or just "in the seat of your pants". You can also have control reversal for the ailerons, as the shock waves are messing around with the pressures that normally result in roll right for right stick and vice versa. Some planes have a pronounced nose-down "tuck", and the only way out is to reduce power and deploy spoilers or speed brakes.

The average "heavy pilot" without military experience rarely sees this. Additionally, the military planes usually have a greater structural margin per the design specification. So we could "push the envelope" in a way you would never try in a heavy. I only exceeded the Vne once, but the jet was robust and my biggest clue was that with a great amount of back stick the thing was not moving as much as I expected. Glanced at the airspeed and sure enough, I was 40 or 50 knots above the placard ) gotta admit that I was pulling off a heavily defended target and was getting hosed down big time by bad guys). You can't do that in a modern airliner, that is, gradually recover from the overspeed without ripping the wings off.

As Doze and others have repeatedly stated, most military and commercial heavies have not had the traditional control "feel" since the 50's. Move the hydraulic valve with the stick/yoke and the pressures went to the control actuators. Clever engineers used feedback devices to "stiffen" the controls at high "q" and to limit the control movement, while providing a sense of the Cessna/Champ/Cub "feel". Big deal.

Comparing control "feel" with the military FBW systems is not fair. We flew at AoA's and speeds and gees not applicable to the heavies. We flew by our own "feel", and the FBW confusers allowed us to ask the jet to do as much as it could without being too worried about stalling or exceeding the structural limits.

One way to "help" the pilots with the FBW system is to employ some of the PC game technology and have forces applied to the controls according to the flight conditions. In other words, use actual pressures detected upon the control surfaces themselves to be "felt" by the pilots. Can also use basic air data like dynamic pressure as a baseline - go fast, stiff stick, slow down and get sloppy and need more control displacement.

enuf war stories, and I continue to read the report again and again, as well as the neat posts here.

GarageYears

4th Aug 2011, 16:36

First, and not least, is the SS. The SS is only lacking in 'performance' relative to its Human counterpart. There is no need for each Pilot to see his counterpart's stick, period. Not if CRM, and a strictly no nonsense environment is followed. That is how I see it. Does PJ2 agree?

Bear :ok:

bearfoil

4th Aug 2011, 16:40

rudderrat

How do. It is especially important in emergency situations that the "other stick" be unavailable, visually. It is a distraction, a potentially lethal one.

If things are bad enough in the cockpit to doubt your counterpart's actions, it is CRM that must rule, not a "second guessing" that is a detriment to one's own responsibilities. Everything up to the simultaneous (and Dangerous) actions was defensible, from a command standpoint. Imo.

I might be wrong, but at this point I believe it might have been Airbus' purpose to isolate the two sticks, and if so, I can see why? Only one can LEAD, and only one can CONTROL, at any given time. It is at the point where these separate functions start to "Blend", that Satan starts to grin?

RatherBeFlying

4th Aug 2011, 16:44

There is no need for each Pilot to see his counterpart's stick, period. Not if CRM, and a strictly no nonsense environment is followed.in an ideal piloting environment I could perhaps be persuaded.

But when humans are involved, errors will happen.

PNF may have clued in had he seen his ss sitting on the back stop.

My underlying concern is that when stuff goes wrong, good information is needed for the crew to put things right.

Among other factors, ss position and some red on the altitude/VSI display might have alerted PNF even though it seems he was too nice a guy.

PNF does not seem to have had any positive ideas about what needed to be done -- nor did CDB.

3holelover

4th Aug 2011, 16:50

Forgive my ignorance of French please, but is there different language used in French for "Pitching" up/down vs "climbing/descending"? The use of phrases such as "you're going up" and "you're going down", sounds (in the transcript) to me to have added to confusion.

Pj2;
There is a difference in FBW in the busses... The "feel" in your hand is simply spring pressure which won't change at all with speed, whereas in older, hydraulic and cable beasts, the control column and cables would actually change the force required to move them with speed. (through the "trim, feel and centering mechanisms") ...and I think (but can't seem to locate my books at the moment) still in the 777, while being the same FBW style electron flow output, the force req'd at the column is adjusted with speed... somehow (damn, where are those books!) force xducers(?) -or is it the backdrive actuators? (I can't remember, dangit. ...maybe I'm wrong about that :hmm:)

In any case.... none of that changes how a human pilot would "feel" the changes in g acting on his body from his actions during a stall vs during an overspeed.

bearfoil

4th Aug 2011, 16:55

RatherBeFlying...

Do you see how "Two Pilots-One Stick" is a recipe for disaster? Take your own, only. It is not an instruction flight. "What's he Doing?" Is as Lethal as "What's it doing?"

This is not......"Francois, follow me through...."

3hl....

Again, in defense of IMC, feel is not necessarily desirable. It would seem, in a very real way, that PF may have allowed his own kinesthetics to drive his decisions? And to the contribution of LOC? Can we entertain a new descriptive? "Loss and MAINTENANCE of LOSS of control" ? Feedback is in some way an enemy of Instrument flight? If there is a total breakdown of systerms, well, ok, but that isn't happeneing here? If, in an emergency, a pilot has ONLY feel, well, ok, but otherwise there is a definite lack of engineered blend of seat of pants/FCS "Co-Operation"? More's the Pity? Will there need be hardwired ButtCheeks?

GarageYears

4th Aug 2011, 17:01

I think (but can't seem to locate my books at the moment) still in the 777, while being the same FBW style electron flow output, the force req'd at the column is adjusted with speed.

Well, not sure that would help a dime once suffering UAS.... or stalled and doing 170knots at FL380... next we'll be suggesting alternate gains that come into play. It gets complicated doesn't it?

hetfield

4th Aug 2011, 17:13

There is a difference in FBW in the busses... The "feel" in your hand is simply spring pressure which won't change at all with speed, whereas in older, hydraulic and cable beasts, the control column and cables would actually change the force required to move them with speed.I have mentioned that before.

This accident wouldn't have happened in e.g. 727 just of the feeling on the elevator.

AND

it would not have happened with a reliable stall warning, stickshaker/- pusher.

AIRBUS, where is your extraordinary sience?

A bungee for monkeys?

airtren

4th Aug 2011, 18:00

...

Why did PF nose up initially? It was accidental. No verbal announcement, no increase in thrust etc. At that it appears there is no reason for a climb.

xcitation,

I've asked the question myself, and have contemplated several speculative explanatory scenarios, due to the limited official information at the time. I've posted one of the scenarios a week, or two, before the BEA report was made available. The posted scenario was that at AP disconnect, the AP was in the process of responding to a drop in altutude, and roll due to heavier turbulence, which was interrupted by the AP disconnect. So the PF reaction was to continue the AP's action with NU, and roll.

The BEA Report made available recently brings more information.
The graphs at the end of the document seem to provide several concurring elements to support the scenario I've considered:

1. there is a slight altitude drop on the Altitude graph, right before the AP disconnect - see page 108 of the English version of the report. The drop is very small, and it's hard to tell how much it is - maybe around 100 ft or so - as the graphs scale corresponds to 35000 ft or so, but Zooming IN, helps seeing it a bit better, within the limits of the graph resolution, and scale.
The altitude drop coincides with a reduction in thrust - see the N1 Actual Eng1% and Eng2 % graphs - and increased roll - see Roll graph.

2. the Normal Acceleration graph, which if I understand correctlty is a reflection of the Turbulence, shows increased up/down air turbulence activity right at that time.

So, I think, turbulence, drop in altitude (with reduced thrust) and roll, were the factors that the PF was responding too with Roll and NU.

I have a vague recollection of seeing posts tangentially, or directly mentioning the same thing, but can't recall exactly which ones.

Welsh Wingman

4th Aug 2011, 18:01

Well said. Much food for thought - enough to write a book, rather than a post, on current automation, the human/machine interface and line pilot airmanship standards/training. As you say re: FCOM......

Not the time/place for F/Os 32 & 37 to suddenly do their FLT350 hand flying training, under AB alternate law in UAS conditions in that part of the circadian rhythm over the ITCZ, but the CRM shortcomings now disclosed really didn't help matters. The PF tossed his coin, called heads (overspeed) rather than tails (stall), the PNF missed his opportunity early on to reach the right conclusion (I don't like the entire SS concept, but that's my prejudices and I won't impose them upon others) and the CPT never appeared to remotely catch-up with his plane in the apparent absence of any meaningful coherent reporting from his co-pilots as to what had already transpired.

All very sad, over in minutes, but a very long time being made by the industry......

hetfield

4th Aug 2011, 18:13

Air France (http://www.flightglobal.com/landingpage/air%20france.html) has formally submitted concerns over the stall warning system in the ill-fated Airbus A330-200 (http://www.flightglobal.com/landingpage/330-200.html) lost over the South Atlantic, after further clarity over the crash of flight AF447 prompted fierce defence of the aircraft's pilots.................Air France said: "At this stage there is no reason to question the crew's technical skills." Stall warning controversy haunts AF447 inquiry (http://www.flightglobal.com/articles/2011/08/04/360336/stall-warning-controversy-haunts-af447-inquiry.html)

VGCM66

4th Aug 2011, 18:43

Third time, first timer,

It was already said by the BEA, there was nothing wrong with the plane and IMHO the same can't be said about the PF. I was under the impression (and for more than two years) until reading the third interim report by the BEA in English, that the younger co-pilot (relief pilot) was the PF. But it never added up completely because, why experience didn't prevail? It did. Also, I couldn't understand why the most experienced co-pilot was screaming for the Captain to return? He didn't, it was the younger one and PNF. It is funny (Life likes that) that the Captain asked if the co-pilot (First Officer) had a pilot license online. This was omitted in the Interim Report #3 for some reason, I think, I can't find it.

FO: But I’ve been at maxi
nose-up for a while = He has been wrong far too long.
Cap: No no no don’t climb = Right but too late. Around under 4000 ft to impact too late.

Relief Pilot: So go down = Yes, but too late and not for long.

I got the complete picture now. I do not see how can we find the mark of a pilot before he/she goes under a real fire event. All the bells, whistles and gadgets won't work if no one pays attention to them or worst yet, decides to disregard them. :ugh:

Welsh Wingman

4th Aug 2011, 18:57

You were correct first time. F/O 32 was PF in the RHS throughout. F/O 37 replaced the CPT in the LHS. F/O 37 had been resting (dozing) until not that long before the incident, which may partly explain his initial failure to get on top of the matter (UAS SOPs etc). Back to PJ2 - sitting for hours monitoring systems and then the speed of this emergency requiring instant quality hand flying airmanship skills (why the particular pitot tube model problem should have demanded a more urgent response, given the modern "hand flying" training and operating environment, given the history from Stony Point via Birgenair and Aeroperu)....

VGCM66

4th Aug 2011, 19:56

You were correct first time. Bonin was PF in the RHS throughout. Robert replaced Dubois in the LHS. Robert had been resting (dozing) until not that long before the incident, which may partly explain his initial failure to get on top of the matter (UAS SOPs etc).

So the youngster got a hold of the SS and from then on the FO was reluctant to take it back away from him until the very end? In both scenarios it seems that the FO dropped the ball (no assertion). It doesn't make sense from his shoes. So, he was the one screaming for the Captain to return? And the Captain before leaving said at one point: He (FO) will take my place? If so, that kind of place him in charge, doesn't it?

What an innocent mess? :ugh:

wallybird7

4th Aug 2011, 19:56

I know this is simplistic, but I'm not sure many here are aware of some of these fundamentals.
Knowing what to do and demonstrating that you can do it are two different things.
BASIC FLIGHT INSTRUCTION AND TRAINING
SIMULATOR AND FLIGHT TRAINING
I think there is a basic mis-understanding of what flight training is all about.
Following a pilot's initial training in any aircraft, in upgrading to a commercial airplane there is a series of stages. From basic flight to specific maneuvers visually and under instruments.
Assume the basics are known and understood. Push forward go down, pull back go up etc.
Whenever a training/simulator session is set up, the rules are understood. Altitude: 100 feet plus or minus. Heading: plus or minus 10 degree. Airspeed: plus or minus 10 kts.
Whatever procedure is being attempted, these criteria must be adhered to. It requires extreme focus, and development of feel and touch.
In dealing with an emergency, whether a fire, loss of engine or anything less, it then requires coordination to handle each one. If the pilot flying tries to deal with the procedure, it is not possible to read and follow the checklist at the same time.
The proper protocol is to hand off the flying to the other pilot who is them responsible for keeping the plane under the foregoing limits, while the pilot reading the checklists assures that each component complies.
But well before this, while knowing what these limit critieria are, a pilot must be able to demonstrate a capability of doing so.
Knowing what the plane can/should do is different than doing it and demonstrating it.
Without ever handling a plane/simulator it is not possible to accomplish any of this the first time out. Let alone in a real life situation, with turbulence and stress.
Here, with many different laws and conditions without hands on training in each phase, successful flight is literally impossible, as we are seeing in this last 4 minutes.

Welsh Wingman

4th Aug 2011, 20:18

CDB even had to check, when he switched with the dozing F/O 37, that F/O 32 was qualified to implicitly take command as the PF (and had been the PF from GIG). Given my vintage, don't even get me started on reinforced crews issues (2 CDBs and 1 F/O, not vice versa!). But save only for the ITCZ (and the CMB that triggered the disaster through the pitot tube failure), it should have been an uneventful systems monitoring leg of the oceanic transit. F/O 37 had not been placed in command as the more "senior" of the two F/Os, and the BEA are criticial of the lack of designated roles for F/O 32 & F/O 37 before CDB departed for his rest break, and note F/O 37's concern at the delays in CDB returning to the cockpit (F/O 37's actions, or lack thereof, are likely to feature further in the final report - psychologists/behaviourists etc).....

spagiola

4th Aug 2011, 20:43

3holelover:
Forgive my ignorance of French please, but is there different language used in French for "Pitching" up/down vs "climbing/descending"? The use of phrases such as "you're going up" and "you're going down", sounds (in the transcript) to me to have added to confusion.

Pitching up is "cabrer".

The PF uses this, at one point:
2 h 13 min 40
PF: Mais je suis à fond à cabrer depuis tout à l’heure
But I'm nose up to the limit since earlier

And then again 2:14:05.

Pitching nose down would be "piquer"

It also struck me how (with the few exceptions just noted), neither PF nor PNF, nor the CDB once he returns, ever speaks of pitching up or pitching down. They constantly speak of going up and going down.

Old Engineer

4th Aug 2011, 21:01

I've deleted this post as I misinterpreted the selected vertical speed (green line) to be intermittant commands in the A/C computer, whereas they are intermittent sampling of commands having continuous effect (as I interpret takata's comments below). I'm leaving this line so as to not change all the following post numbers. --OE

DJ77

4th Aug 2011, 21:08

Also, the Airbus side stick does have artificial feel just like a control column/wheel and it works very well.

I thought the Airbus side stick was simply spring-loaded to neutral. I would not call that an artificial feel.

An a/c with mechanical controls sends back two qualitative messages to its pilot as regards the pitch axis.
1/ speed: whether you are fast or slow, the stick is stiff or limp.
2/ trim: the residual force on stick required to maintain an attitude tells you where you are relative to you trim speed
I believe an Airbus side stick conveys neither speed (C* law) nor trim (autotrim). Or did I missed something ?

takata

4th Aug 2011, 21:13

Hi VGCM66,

It was already said by the BEA, there was nothing wrong with the plane and IMHO the same can't be said about the PF. I was under the impression (and for more than two years) until reading the third interim report by the BEA in English, that the younger co-pilot (relief pilot) was the PF.

One day, considering that final BEA report will not be published before next year (1st semester 2012), we'll have to make a FAQ about this thread for "First Timers" who seems to be lost in BEA reports translation... but, believe me, I understand perfectly the issue.

So, lets go for one more explanation:

1. "Relief" pilot, in Air France terminology, means "co-pilot (F/O) acting as Captain"; hence, he is the pilot in charge (PIC) when the captain is resting. It is not the same meaning than "limited duty officer", for "relief" at cruise, like many other companies are calling it.

2. Air France longhaul crews are composed of the "commandant de bord" (captain) and two fully qualified co-pilots (F/Os) having the exact same rank (whatever their age).

3. When captain is leaving the deck, he should decide whilch one of his two F/Os will be the pilot in charge (PIC) during his rest.

4. The officer designated as PIC must be the pilot flying (PF) during his rest. (this part was changed after AF447)

Consequently:
AF447 used this system and when Captain (no name please) took his rest:
- Pilot Flying (PF), being the pilot in charge (PIC), was the 32 years old F/O and was seated in RHS (Co-pilot seat in CVR/DFDR table).
- Pilot Non Flying (PNF) was the 37 years old F/O and was seated in LHS (Captain seat in CVR/DFDR table)

Quite disturbing, isn't it?
:O
All along this thread, we are refering to the, Captain, PF (RHS) and PNF (LHS) as at 02:10UTC. But at some point, PNF could be the one flying the aircraft !

Welsh Wingman

4th Aug 2011, 21:31

Your post should be mandatory for all new joiners to the thread.

As regards your question, you may imply that but I could not possibly comment......

MountainWest

4th Aug 2011, 21:36

I don't think we can deduce much from the given fractional positions of the stick. It could just as well have been given as a percentage or in another base. The stick position will have been converted to a voltage, and the voltage then digitized, for input into the computer, perhaps with some cleanup along the way, before being recorded on the FDR. The fractional notation is for ease of digestion by the reader.

Sampling rates are another issue. Could be anything, from the rate you suggest to some artifact of processing the data. The sampling rate, recorded stick position, and other recorded data are chosen for logical reasons, and would not be limited by the speed of the computer.

Perhaps SensorVal or others would care to elaborate.

Lonewolf_50

4th Aug 2011, 21:42

Bear:
... why would the crew speak twice of Altitude, than finally, "hoping a Pull Up, we are at 4000".
What matters is what they think of what THEY spoke!
"@9000......@8000" one second after the other.
I've called out altitudes in a descent as an alert to a PF more than once. Tone of voice will vary with situation.
Does one of them not 'get' the VSI, and someone is trying to REMIND? At 8000, than 4000 feet? To me, and it is a GUESS, it means they are worried about Overspeed, ... why, In my opinion, they were not speaking STALL!

As in: Captain : "N'est-ce pas possible!!" "****in A, we're STALLED"

Indeed, he may have been thinking that, but as I noted above, had to deal with the denial phase of a pear-shaped situation. He went about other tasks, as there were plenty to choose from, or so it may have appeared to him.
Three qualified Pilots ignore STALL WARNINGS and input near constant NOSE UP.
The fellow in the RHS seems to have done most of that, even with Monsieur Robert nagging him about his nose attitude. Somewhere in this discussion, I see some ideas that even after the control change, you had two people trying to move the control stick. That isn't good. :(
You are not mistaken at all. PF disabled PNF stick, using priority, during the last 10 seconds or so. Note that the last imputs from the PNF reverted also to nose down. The vast majority of his few imputs were ND anyway.

(This is Not Colgan for silly sakes)
I mentioned that to Dozy when he first brought it up. I agree with you on that.
"I think we have crazy speed!"
Is he saying "Way Fast" with no airspeed indication? Disorientation, evidence of.
HN[/B]] Correct, but don't forget that static pressures are affected also, reading high. Pitot minus static can become negative in extreme cases, as mentioned in one of the BEA reports.
Why is static reading high? Ice, or something else?

Smilin' Ed: OK, I see where you are coming from.

Machinbird: The computers/ADRs, it appears, cannot be trusted with the data in extreme conditions.

That may be true, but I don't think A330 was designed with "extreme flying" in mind. ;)
Essentially airspeed has been given authority to outvote AOA (which we already knew from the stall warning fiasco) but this is not a good situation for present and future AOA installations in Airbus aircraft. This I consider to be a fundamental engineering error, but one that can fixed, probably by better software.
I use the word error, because AOA and airspeed are both fundamental aircraft performance data, but independent of each other and derived independently. To then mix them together and prioritize them is simply bad logic.
Food for thought.

BOAC To anyone puzzled by the nose-up 'pull' at 4000', I ask what exactly would you suggest they did instead at 4000' with around 10,000 fpm down? I think we are down to pretty basic human instinct here.
If nothing else was working, revert to basics. I might have done the same, if I didn't realize I was stalled. Try something, anything.
".the copilots had not received any training, at high altitude, in the “Unreliable IAS” procedure and manual aircraft handling."
Is this perfectly normal and would this apply to other airlines as well?

One hopes not.
... I keep wondering about the FD's. As you said, when reengaging, they take the altitude of the time as their new reference, and the horizontal bar will (with the plane diving down ) give an UP order to the pilot, who is trained to follow it.
They(the FDs) should have been switched off on both sides from the very moment when the loss of valid airspeed indications became clear to the pilots : emergency procedure on page 81

In fact they (the Fds) were not cut off, so the bars on the displays kept coming on, then off, and one wonders if the horizontal bar, which one is trained to following, was not one of the reasons the flying pilot kept pulling upwards ?

Food for thought.

infrequentflyer789

4th Aug 2011, 21:54

in an ideal piloting environment I could perhaps be persuaded.

But when humans are involved, errors will happen.

PNF may have clued in had he seen his ss sitting on the back stop.

My underlying concern is that when stuff goes wrong, good information is needed for the crew to put things right.

Among other factors, ss position and some red on the altitude/VSI display might have alerted PNF even though it seems he was too nice a guy.

PNF does not seem to have had any positive ideas about what needed to be done -- nor did CDB.

PNF seemed perfectly well "clued in" when it all started to go wrong - he knew PF was over controlling roll and chastised him for it, he knew PF was climbing when he shouldn't have been. In fact PF is the one who seemed unaware of what he was doing with his own SS.

None of them seem to have recognised stall, even when the warning was continuous, no recovery is ever discussed or actioned. With the possible exception of TOGA - not sure about that, I almost get the sense that PF is saying "can't be stalled, I'm in TOGA", but can't be sure (anyone else read it that way ?). In fact looks like PF thinks he's over speed if anything.

Captain I feel sorry for, he comes back in to stall warnings, AOA already so high that instrument data is going haywire left right and centre, no visual reference, and he has to work out what's happened without any info other than "we lost it". He has only 2 mins to diagnose stall and have the confidence to order 30deg or more nose down to attempt a recovery. I don't think hereally had a chance to save it from then.

overthewing

4th Aug 2011, 21:58

AF447 used this system and when Captain (no name please) took his rest:
- Pilot Flying (PF), being the pilot in charge (PIC), was the 32 years old F/O and was seated in RHS (Co-pilot seat in CVR/DFDR table).
- Pilot Non Flying (PNF) was the 37 years old F/O and was seated in LHS (Captain seat in CVR/DFDR table

I get more and more confused. Could we agree whether the following was true?

1. The officer who was resting prior to 2am was F/O 37.

2. The officer who 'wasn't sleepy' was F/O 32, who has also been PF from Rio.

3. The Captain woke F/O 37 and said (to F/O 32) that the older officer was to 'take my place'. By this he meant F/O 37 was to sit in the LHS, not to be PIC.

4. The Captain asked F/O 32 if he was certified, presumably to be PIC from the RHS. Presumably this question had not arisen on the outward leg.

xcitation

4th Aug 2011, 22:04

I've asked the question myself, and have contemplated several speculative explanatory scenarios, due to the limited official information at the time. I've posted one of the scenarios a week, or two, before the BEA report was made available. The posted scenario was that at AP disconnect, the AP was in the process of responding to a drop in altutude, and roll due to heavier turbulence, which was interrupted by the AP disconnect. So the PF reaction was to continue the AP's action with NU, and roll.

The BEA Report made available recently brings more information.
The graphs at the end of the document seem to provide several concurring elements to support the scenario I've considered:

1. there is a slight altitude drop on the Altitude graph, right before the AP disconnect - see page 108 of the English version of the report. The drop is very small, and it's hard to tell how much it is - maybe around 100 ft or so - as the graphs scale corresponds to 35000 ft or so, but Zooming IN, helps seeing it a bit better, within the limits of the graph resolution, and scale.
The altitude drop coincides with a reduction in thrust - see the N1 Actual Eng1% and Eng2 % graphs - and increased roll - see Roll graph.

2. the Normal Acceleration graph, which if I understand correctlty is a reflection of the Turbulence, shows increased up/down air turbulence activity right at that time.

So, I think, turbulence, drop in altitude (with reduced thrust) and roll, were the factors that the PF was responding too with Roll and NU.

I have a vague recollection of seeing posts tangentially, or directly mentioning the same thing, but can't recall exactly which ones.

Very important point. So...

AP disconnects
a/c at 0 deg pitch => will descend
pilot stick back 3/4 causing nose up pitch 11 deg.
climb rate goes up.
after 4 seconds first stall warning
after 15 seconds altitude has not changed (downdraft/reduced thrust?)

So PF was correct to stick back but he over does it.
Stall alarm sounds, he eases off on the stick pushes it fwd briefly, alarm stops.
Then he resumes stick back to maintain altitude.
Now the THS starts helping PF to pitch nose up.
Now he is gaining altitude with help from THS.

Report #3, Page 111, Longitudinal parameters

Notice the insidious influence the auto THS (cyan) has on elevator position. At some points he is stick forwards (red line, 02:12:17) yet elevators stay around -30 deg (purple). Clearly this would add to the confusion of inputs.

3holelover

4th Aug 2011, 22:06

Thanks Spagiola. Using those phrases ("going up"/"going down") sure seems to hinder understanding.

Welsh Wingman

4th Aug 2011, 22:07

Yes, save for your final sentence under (4). This was not the same crew that had flown out, if my memory serves me well (e.g. PF had been on holiday with his wife, without their children, on board the flight).

john_tullamarine

4th Aug 2011, 22:11

I've had some complaints regarding French translations and offensive text. Not being a French speaker, I am a bit out of my depth with such problems as, to quote the saying, "it's all French to me".

If you have a problem with French text as posted, by all means send me a PM with details.

Due to the present day job workload, I am a little behind in my monitoring of this thread. I expect to catch up in the next few days.

SaturnV

4th Aug 2011, 22:18

overthewing, that's correct. Although I don't know if the FO who was PF at 0200 had been PF since Rio.

welsh wingman, the crew apparently flew together from Paris to Rio. There was a long layover scheduled, and it was also Pentecost Sunday weekend, so the wife of the junior FO traveled to Rio for a short holiday.

jcjeant

4th Aug 2011, 22:25

Hi,

takata
2. Air France longhaul crews are composed of the "commandant de bord" (captain) and two fully qualified co-pilots (F/Os) having the exact same rank (whatever their age).Sorry to return on the work bench .. but ...
Seem's the "commandant de bord" (captain) was not aware of the Air France rules concerning the longhaul crews :eek: .. as it's written in the BEA report interim N°3 that the captain asked to the F/O Mr NoName 32 years old if he was a "fully qualified co-pilot"
Again I repeat .. it's a odd question coming from an AF captain.

CONF iture

4th Aug 2011, 22:26

I fought very hard when active, to retain the authority to hand-fly the aircraft but lost the fight when the FCOM was revised to require engagement of the autoflight system "from just after takeoff to touchdown".
You must be talking about the SOP part of the FCOM which is adapted to the need and will of each Airline.
But thanks GOD, most still apply commun sense.

A33Zab : Can anyone explain this?

http://i45.servimg.com/u/f45/11/75/17/84/wiz_pi10.gif (http://www.servimg.com/image_preview.php?i=107&u=11751784)

Very bizarre - Not a word on it in the last interim report ... !?

For the last minute (and probably much more ?) before and up to the UAS, there seemed to have continuous and repetitive 'automatic' switching between V/S mode and some other vertical mode (?) Was it a kind of reversion transparant to the crew ?

Selected v/s was nothing else than -5000 ft/min ...

What is the consequence on the initial climb ?
What is the consequence on the LOC ?

That thing is not minor, and must be addressed - Anything to do with the WRG message ?

Welsh Wingman

4th Aug 2011, 22:31

Thanks for clarification re: the long layover (long enough for F/O 32's wife to holiday). Don't like using (deceased) pilots names, but sometimes it just causes less confusion in the end.

overthewing

4th Aug 2011, 22:41

Although I don't know if the FO who was PF at 0200 had been PF since Rio.

Think I'm inferring from the following:

Towards 22 h 10, the crew was cleared to start up engines and leave the stand. Takeoff occurred at 22 h 29. The Captain was PNF, one of the copilots was PF. (BEA Interim Report)

The Captain proposed that the copilot take a rest due to the length of his shift. The latter answered that he didn’t feel like sleeping. (BEA Synthesis note)

Therefore I'm assuming that the pilot who went to rest was the one who was called back around 2am, ie F/O 37, and F/O 32 had been flying since Rio.

takata

4th Aug 2011, 22:44

Hi Old Engineer,
Q: My final question... Am I missing something here? Is this meaningless speculation?
Yes! but you really did such a great job at missing close to everything!
:p
A33Zab did ask about the meaning of Vertical speed selected graph... (I suppose, did you Zab?). Which graph depicts something unrelated with... (I don't know what your post was talking about - seems imput logic?).

Vertical speed selected is a manual setting for: vertical speed ! (surprisingly)
This function is used by autopilot only.
This graph is showing the VSS value after reseting to current flight level due to intermintent returns of flight directors (as they were never turned off).
http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif

Welsh Wingman

4th Aug 2011, 22:50

Affirmative. It also explains why F/O 32 was the obvious choice to carry on as the PF and become the relief pilot (given the pre-AF447 position as set out by takata).

Old Engineer

4th Aug 2011, 22:53

MW

Thanks for your comments. In addition to that, I realize now that I completely misinterpreted this graph as representing the actions of the aircraft. After a lot of careful reading, I see that the graph indicates, intermittantly, the settings within certain of the computers. These settings continued to have effect continuously, as I now understand it.

So I think my post will not be useful to the discussion and am going to delete it. I'll plead to being my own French translator. :)

Although, above @ #1556 CONF iture has posted this graph again, with the comment "Selected v/s was nothing else than -5000 ft/min ...". And he closes with "That thing is not minor, and must be addressed - Anything to do with the WRG message ?".

I'm noting that this -5000 fpm appears to be without flight deck input, so I'd say the graph is saying something critical to us.

xcitation

4th Aug 2011, 23:01

I'll plead to being my own French translator.

The english report is out.
Link can be found a few pages back.

SaturnV

4th Aug 2011, 23:04

How did the crew get to where they were at 0208?

0 h 30 mn The crew received information from the [AF] OCC on the presence of a convective zone linked to the ITCZ between SALPU and TASIL

1 h 35 mn 46 No response from AF 447 to ATLANTICO's request for the estimated time at TASIL

1 h 35 mn 49 Copilot’s ND scale changes from 320 NM to 160 NM.

[B]1 hr 50 mn 35 The radar display mode changes from WXR ONLY to WXR+TURB. The Captain’s ND scale changes from 160 NM to 40 NM.

[A little later [after changing the scale] he [the Captain] mentioned the appearance of Saint-Elmo’s fire and said that “it’s going to be turbulent” when he went to take a rest.]

2 hr 00 mn 17 Copilot’s ND scale changes from 160 NM to 80 NM.

2 hr 01 mn 46 Captain leaves the cockpit

2 hr 08 mn (approximately) The copilot in the left seat moved the weather radar gain control to maximum, after noticing that he was in calibrated mode.

2 hr 09 mn 53 Copilot’s ND scale changes from 80 NM to 40 NM.

"The signal corresponding to the “fasten seat belts” information was not heard on the recording."
_____________________________

The following English translation appears to be an extract or summary of AF procedures on use of weather radar.

1.17.3.2.2 Instructions for use of weather radar
In cruise mode above 20,000 feet, a slight downwards adjustment of tilt, depending on the scale selected, is recommended so that the ground echoes only appear on the ND at the edge of the furthest distance circles. This method enables the simple and practical application of the height/tilt rule of equivalence providing the optimum tilt adjustment.

When pilots monitor the weather situation, gain can remain in CAL position. In the confirmed presence of storms and during their avoidance, a manual adjustment can be used for comparison with the CAL image.

A scale of 160 NM enables the change in the weather situation to be assessed and anticipate route changes. A scale of 80 NM is used for avoidance. Short scales must be periodically discontinued in order to observe distant weather conditions and to avoid an impasse amid the disturbances.

The shape of the echoes may alert the crew to the possible presence of hail. Zones of turbulence may be presented above a detected zone of precipitation.

Red or magenta zones as well as fringe-shape echoes must in this way be by-passed from windward by regularly adjusting the tilt and the range. The avoidance decision must be taken before the echoes are at 40 NM.

The operator recommends avoiding flying less than 5,000 ft above or below a storm cell. It provides a formula for pilots to estimate the separation height between the top of a detected cell and the airplane. This formula uses the distance and the tilt points from which the zone echo disappears. Above 23,000 ft, it is recommended to fly more than 20 NM from these zones. (Compensated by 50%, that is 30 NM for U- or finger-shape echoes or with scalloped edges (storms, presence of hail).

In CAL mode without adjusting tilt, the BEA report notes that ice crystals will be hard to detect. The report also notes that "An oceanic cumulonimbus reflects radar waves less than a continental cumulonimbus cloud of the same size and height."

The change in gain from CAL to MAX on the PNF display was not made until 0208. There was apparently no change in tilt over this period.

Old Engineer

4th Aug 2011, 23:06

takata,

Saw your comment in the "reply" window on recent comments. It's gone, but it made me smile. I'll never be a French speaker until I understand that they omit all information that would make themselves clear to outsiders. :)

Sorry to add to your workload of keeping things straight.

excitation,

Yes, I knew that; just thought the French would be closer in meaning.

CONF iture

4th Aug 2011, 23:12

This graph is showing the VSS value after reseting to current flight level due to intermintent returns of flight directors (as they were never turned off).
No takata, we're not talking after but before !

What was the issue on the FDs before ... ?

bearfoil

4th Aug 2011, 23:35

Let me see if I can confuse the issue further. The Vs 'Zipper' coincides with the THS Zipper I noted earlier. Roughly one second control inputted POSITIONS, of VARYING value, approximating 1.5 degrees deflection, EACH WAY. Yes CONFiture, this is in autopilot, nine secs continuous prior disconnect.

Tell me it's in the FCS, and I'll be on my way. For you must know, just because bear notices something does NOT mean he 'gets' it. Also, I don't believe the ship is this.....erm, AGILE. Let's ask gums.

gums

4th Aug 2011, 23:39

Since the late 60's the only feedback to the control stick/yoke has been artificial. Exceptions were the planes with mechanical linkage to the control surface actuators, and even those had little "direct" feedback. We called it "boost". We also saw yaw and pitch dampers that the clever engineers provided us to "help" keep the pointy end forward and reduce pilot-induced-oscillations, etc. The VooDoo and Phantom and others had bellows that used pneumatic pressure from an "orifice" someplace to stiffen the stick. We also had bobweights to provide a gee indication on the stick. Real easy, and kept us from commanding more gee than we wanted using only a direct hydraulic valve. OTOH, roll was usually a simple spring mechanism that made it harder to command left or right the further you deflected the stick/yoke. No dynamic pressure feedback, just a spring doofer.

For the non-pinball wizard pilots, some type of force feedback for the stick/yoke would be nice. Unfortunately, airframe vibration or buffet is different. You have to have "touch", and you cannot teach "touch". Helped many young pilots learn to fly a new jet ( three of them), but I could never "teach" "touch".

"Can't you feel that?"

"No sir."

"lemme do it and follow me thru"

etc.

Many of we old dinosaurs would like an electronic system that "feels" like the old planes. This is possible, maybe even preferred. But in the end the pilot has to trust the instruments ( unreliable and confusing as they were with AF447) and somteimes rely upon some "touch" as to how much should I pull/push, and is it a mach buffet or stall onset, or a big piece just fell off ( the 'bus incident when tail came off due to excessive commands by pilot)?

There is no substitute for airmanship, dammit. If the public wishes to ride in an airplane with no human up front, then let's try it for a few months. We could program the jet to takeoff, cruise and land, while avoiding bad weather and making radio calls to appropriate agencies, etc. And when a situation arises that the cosmic engineers had not thought of, then......

takata

4th Aug 2011, 23:41

Hi overthewing,
I get more and more confused. Could we agree whether the following was true?
1. The officer who was resting prior to 2am was F/O 37.
2. The officer who 'wasn't sleepy' was F/O 32, who has also been PF from Rio.
3. The Captain woke F/O 37 and said (to F/O 32) that the older officer was to 'take my place'. By this he meant F/O 37 was to sit in the LHS, not to be PIC.
4. The Captain asked F/O 32 if he was certified, presumably to be PIC from the RHS. Presumably this question had not arisen on the outward leg.
Yes, everything looks right, except for take-off from Rio: I don't know if the F/O was the same PF.

Linktrained

5th Aug 2011, 00:17

The first fully automatic trans Atlantic flight was from Newfoundland to Brize Norton, UK, in September 1947 by a C54.

The idea has not caught on yet ! The flight was from runway to runway, only. Humans were still required on the ground, from and to the terminals.

Lazerdog

5th Aug 2011, 04:25

English interim report location:

FLIGHT AF 447 (http://www.bea.aero/en/enquetes/flight.af.447/flight.af.447.php)

ZimmerFly

5th Aug 2011, 07:42

takata

2. Air France longhaul crews are composed of the "commandant de bord" (captain) and two fully qualified co-pilots (F/Os) having the exact same rank (whatever their age).

3. When captain is leaving the deck, he should decide whilch one of his two F/Os will be the pilot in charge (PIC) during his rest.

This is where I believe the Air France way of doing things is fundamentally flawed. Most other airlines have a distinct chain of command, Captain > Senior First Officer > Junior First Officer. In this case the older, more experienced first officer should have been "In Charge" while the Captain was resting. [This would not prevent the Junior FO controlling the flight and making tactical decisions but may have encouraged the Senior FO to be more assertive when things were not going so well.]

This may have resulted in a better outcome !

hetfield

5th Aug 2011, 07:44

HazelNuts39

5th Aug 2011, 08:20

Hence, airspeed is twice affected (did you try to derivate aircraft actual airspeed from ground speed and other parameters to see at which estimated (true) value airspeed was reading under 60 kt ?). And V/S is also affected (obvious from graph)... and somewhat baro altitude...Hi takata,
Airspeed from groundspeed, V/S, windspeed and temperature is shown on this graph: CASfromGS (https://docs.google.com/leaf?id=0B0CqniOzW0rjNjAzMGRkYmUtZjMwNy00MzBmLWJmMzQtMzIwZjg 2ODYzZDlm&hl=en_GB), It is based on wind 45 kt @125 deg, ISA +11 deg C, DFDR data for v/s, altitude and HDG.

The blue dots are Mach from ADR, pink is Mach from GS, wind and v/s, and the green dots show the corresponding CAS.

JD-EE

5th Aug 2011, 09:40

DozyWannabee, I note that takata's recent note about the plane aimed down when the PF requested NU and your comments about not seeing a conflict in that suggests another basic rule for "strange situations" such as the sudden drop to ALT 2 with no airspeed indication: Don't Play With The Throttles, Bunky.

The moment arm with the engines and their thrust do exactly the opposite of what you think you want. If you are thinking overspeed pull up. But don't drop the throttle. That will nose you down. If you are thinking stall, don't goose the throttle. That will tilt you up and slow you down. So don't play with the throttle.

But, for that matter, don't change anything except roll. Maintain pitch, don't touch the silly throttle, and keep the wings more or less level but fanaticism about it doesn't pay. Watch the altimeter. If it start changing rapidly aim the plane "slightly" to compensate. But don't play with the throttle except for VERY small nudges.

HazelNuts39

5th Aug 2011, 09:58

But, for that matter, don't change anything except roll. Maintain pitch, don't touch the silly throttle, and keep the wings more or less levelRoll control is problematic in the stall. When you're stalled, unstall first, then level the wings.

JD-EE

5th Aug 2011, 10:08

HN39 - I am addressing what to do upon entering ALT 2 with no airspeed indication. Once in a stall first course on the table is admit you are stalled. Second course is nose down with an urgency depending on rate of drop of altitude. Third course is airspeed. Fourth course is a gradual pull up once airspeed is high enough. Fifth course is the dessert of moving back to planned course.

If no airspeed continues use AoA vane as a clue whether you are stalled or not. When it "agrees" with pitch you're good to pull up - gradually. No AoA report in the cockpit? Um, Er, Ah, Boss - you're gonna die?

vanHorck

5th Aug 2011, 10:58

John has updated the very first post in this thread to include some essential links for all newbies here. Thx, great!

Can I also include some excellent weather analysis here: Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data (http://www.weathergraphics.com/tim/af447/) by Tim Vasquez

HazelNuts39

5th Aug 2011, 11:32

JD-EE; Once in a stall first course on the table is admit you are stalled. Second course is nose down with an urgency depending on rate of drop of altitude. Third course is airspeed. Fourth course is a gradual pull up once airspeed is high enough. (...)Agreed, almost. If you have AoA or next best, valid stall warning on/off as a substitute of it, I would put leveling the wings third. If you let yourself be guided by AoA, you don't really need to watch airspeed for recovery and can leave it to course five.

SaturnV

5th Aug 2011, 12:00

van Horck, it would be nice if Tim Vasquez updated his graphics and analysis again, given the additional information in the Third Interim Report. e.g., the turbulence trace, and the sound of ice crystals.

The contrast between what the crew flying AF447 did at SALPU and ORARO and what the crew of AF 459 (35 minutes behind) did is striking. In essence, the crew of AF 447 thought they could ride near or at the top of the clouds, and never gave a second thought to the presence of Cbs, even though they were specifically cautioned about such.

For the lawyers seeking damages, their inattention and complacency is the equivalent of finding a vein of gold with the first dig of a shovel.

Reading between the lines, even the BEA seems at a loss to explain it. It will be interesting to see if the BEA can determine how many of the captain's and PF's rotations to South America occurred on flights through an active ITCZ.

A33Zab

5th Aug 2011, 12:10

CONF iture:
Quote:
Originally Posted by takata
This graph is showing the VSS value after reseting to current flight level due to intermintent returns of flight directors (as they were never turned off).

No takata, we're not talking after but before !

What was the issue on the FDs before ... ?

Exact! and the spikes @ 02:10:16 'CLOSING of the CAS monitoring window & ADR rejections'?

http://i474.photobucket.com/albums/rr101/Zab999/NORM2ALTUNSTABLE.jpg

takata

5th Aug 2011, 12:42

Hi Old Engineer,
I'm noting that this -5000 fpm appears to be without flight deck input, so I'd say the graph is saying something critical to us.
Before AP disconnecting (at 0210:05) the graph is showing a VSS of zero, not -5,000 ft. (one need to read the discontinuous green line) and the red line (real V/S) is not altered in any way by it. It is also showing a different active mode when autoflight is still ON.

The cyclical drops (regular pikes down to MIN value) is certainly due to this autoflight mode (hence normal). In fact, I did not comment on those regular pikes as nobody here knows how those values are sampled. The same channel may be used, when AP is ON, for recording another flight parameter at regular intervals. It looks for me to behave this way.

After FMGECs faults (at 0210:05), the mode change is obvious, next VSS value increase/decrease is now linked with FD resetings. But, before this point, the VSS values (including MIN) are not linked with FD as there is another graph for FDs showing nothing anormal before UAS.

vanHorck

5th Aug 2011, 12:42

SaturnV

I've asked Tim, but he was too busy to come up with an update, he made the document then, to help us in the days when no plane had been found.

I will mail him and ask him again I promise, but he is a busy man......

Update 14:50 Amsterdam time I've emailed Tim and will come back on this if relevant

Linktrained

5th Aug 2011, 12:45

Asymeteric Thrust

Other old(er) Dinosaurs than Gums might recall that the HP42's top two engines needed careful handling on the ground. The tail wheel could lift, unexpectedly.

JD-EE reminds us that asymetric thrust is not only what we practice when one engine is shut down. TWO (or more) Underslung engines have a pitch effect.

( Would that be equal to 4 units of NU trim ? I have no way of telling as my armchair is uncalibrated. I am sure that the answer is "...It depends...")

Takata noticed a small improvement in the recovery from the stall when the power was reduced, all too briefly - and then, sadly, it was restored.

What would I have done as PF ? I have not had the luxury of time to think, to change my mind from climbing with full thrust, to pitching nose down. Closing down BOTH engines to flight idle might be the right thing to do - but would FEEL very wrong. Descending at night through a Cb without any clear Airspeed...I know that my Penetration speed should be between 240 and 260 kts, but how can I tell... I must try to keep my wings fairly level if I can...

Perhaps.... it is as well that my armchair does not feel overloaded, too!

GerardC

5th Aug 2011, 12:51

This is where I believe the Air France way of doing things is fundamentally flawed. Most other airlines have a distinct chain of command, Captain > Senior First Officer > Junior First Officer. In this case the older, more experienced first officer should have been "In Charge" while the Captain was resting. [This would not prevent the Junior FO controlling the flight and making tactical decisions but may have encouraged the Senior FO to be more assertive when things were not going so well.]

This may have resulted in a better outcome !maybe, maybe not.

AF pilot unions have always refused the "distinct chain of command, Captain > Senior First Officer > Junior First Officer" as this would mean less trained/less qualified (read : less paid) "junior F/O".

The underlying idea being : total qualification of the crew is better with one captain and two fully qualified F/O's.

Now, of course, the two F/O's being "equal" means CRM problems can arise as we see here.
Obviously the PNF had a, slightly, better understanding of the mess, but at no time he ordered "my plane" (at the time, F/O's did not get any LHS-flying training).

One last comment, the older/more experienced F/O is not always the best choice for PIC.
Never flown with aging, not very concerned F/O's ?

SaturnV

5th Aug 2011, 13:09

vanHorck, thank you, and thank Tim as well for all his past effort.

The assessment that I would be most interested in is whether the loud noise that can be heard on the CVR of ice crystals hitting the plane indicates they had penetrated the Cb itself, or if not, how close would one need to be to a Cb to get that amount of ice crystals.

I don't recall that the BEA gave sufficient data to correlate the time when the sound of ice crystals can be heard on the CVR and the PNF turns on the anti-ice.

takata

5th Aug 2011, 13:10

Hi A33Zab,
Exact! and the spikes @ 02:10:16 'CLOSING of the CAS monitoring window & ADR rejections'?
Well, not sure. In fact, I'd say that at around 0210:16, speeds could have been coherent again for a very short time and FDs were back, disapearing almost immediately. In between, a new set VSS was sampled, taking the actual value from the real V/S at this exact point.
CAS monitoring doesn't alter the VSS parameter (see 0210:05-0210:15 and subsequent values staying where they were while V/S increased or decreased). Its value freezes to the current V/S when FDs kicks off.

hetfield

5th Aug 2011, 13:20

AF pilot unions have always refused the "distinct chain of command, Captain > Senior First Officer > Junior First Officer" as this would mean less trained/less qualified (read : less paid) "junior F/O".What about Captain / Senior First Officer / First Officer ?

Surely this means a special training for LHS qualification including ground school, sim training, line training with checkout as Senior First Officer.

And yes, pay is inbetween First Officers (not called Junior..) and Captains.

I don't see something wrong with that.

takata

5th Aug 2011, 13:26

Hi Confiture,

No takata, we're not talking after but before !
What was the issue on the FDs before ... ?
Thank you for attracting my attention on this point. It seemed normal to me and no, BEA would not comment something "normal" without good reasons to do so.

Nonetheless, the fact that FDs were not turned off attracted also their attention in order to find what kind of indications could the bars have displayed on PFDs. There is a discussion on it and they are trying to reconstruct everything displayed for analysis. So, I don't think that there is any sort of conspiracy about that, don't you agree?

I really believe that BEA investigators are trying their best as to verify everything, but it takes time, as you know as well, to investigate every single bit of data. You should drop off this attitude of conspiracy as it won't help families or pilots to continue this way by discrediting them constantly.

SeenItAll

5th Aug 2011, 13:26

Is it possible that the F/O who was PNF in the left seat was also reluctant to take control because of a lack of dexterity with the LHS sidestick? As a F/O, primarily sitting in the right seat, his experience and dexterity would with using his right hand. Indeed, I have heard mentioned elsewhere that when two F/Os are on the flight deck, the PF is always supposed to be the one in the right seat.

takata

5th Aug 2011, 13:36

Hi SeenItAll,
Is it possible that the F/O who was PNF in the left seat was also reluctant to take control because of a lack of dexterity with the LHS sidestick?
Very probable, added to the fact that he wasn't sure of his own understanding of events. Very sad in fact as he seems to be always on the verge of doing the right thing.

airtren

5th Aug 2011, 13:53

Certainly this is material for reflection, and better understanding of the moments before, and when all of it started.....

Here is a set of graphs, that may help visualize certain parameters at the moments before the AP disconnect, and passing from Normal Law to Alternate Law - this is the moment of the AP and A/THR disconnects.

A red vertical line marks the moment of the Normal to Alternate Law change.

I notice a Pitch Nose Down, right before the Law change.
I can also see now, that the slight Altitude loss (if the BEA graph is accurate) was right after the Law change. At the time of the previous post, I thought it is before the Law change

One can visualize the increased degree of turbulence based on the areas marked on the 3 graphs of acceleration right before the Law change. There is an increase in up-down-left-right-forward-backward motion. The Vertical Speed around that time also show and increase, and decrease - reflecting the Vertical Acceleration changes.

http://farm7.static.flickr.com/6128/6011922204_217ddffc2b_b.jpg

Very important point. So...

AP disconnects
a/c at 0 deg pitch => will descend
pilot stick back 3/4 causing nose up pitch 11 deg.
climb rate goes up.
after 4 seconds first stall warning
after 15 seconds altitude has not changed (downdraft/reduced thrust?)

So PF was correct to stick back but he over does it.
Stall alarm sounds, he eases off on the stick pushes it fwd briefly, alarm stops.
Then he resumes stick back to maintain altitude.
Now the THS starts helping PF to pitch nose up.
Now he is gaining altitude with help from THS.

Report #3, Page 111, Longitudinal parameters

Notice the insidious influence the auto THS (cyan) has on elevator position. At some points he is stick forwards (red line, 02:12:17) yet elevators stay around -30 deg (purple). Clearly this would add to the confusion of inputs. (http://www.pprune.org/view-source:http://farm7.static.flickr.com/6127/6011656448_3f74c00ac8_m.jpg)

safetypee

5th Aug 2011, 14:01

SaturnV, “… how close would one need to be to a Cb to get that amount of ice crystals.” # 1584.
Some research and flight tests suggest that significant amounts of ice crystals can be found up to 10-15 nm from a Cb (measured from the edge of the red zone).
From experience around and in Cbs with ice crystals, it is most unlikely IMHO that AF 447 entered a Cb core, although the aircraft may have passed through or over the tops of smaller cells.
Ice crystals can be heard – a sort of swishing sound; this is often accompanied with a very wet windscreen (screen heating), which adds to the confusion. Furthermore the ice crystal cloud is very tenuous and might not even be classified as IMC in some circumstances.
Louder, harsher noises come from hard hail often found in the same situations, particularly over the core; this can be heard clearly and might on occasions sound like rain.

The best advice is to stay well clear of Cbs, the avoidance distance (from the edge of the red zone) being proportional to the size of the core. I have encountered signs of outflow cloud up to 60nm in one Caribbean cell and 100nm from a huge cell in Africa; basically any anvil cloud can have a high concentration of crystals.

Just because modern aircraft have high tech radars which automatically detect the severity of ‘this, that and everything else’, and in multicolour, does not imply that technology understands the effect of the conditions on a particular aircraft type, or on a on a type thought not to be susceptible, but now operating with different performance parameters, e.g. engine power, TAT.
Ice crystals caught the industry napping several years ago with engine problems – the engine design had changed, not the weather. At the time there were signs of blocked ‘tubes’ and overpowered heaters (TAT) but no connection was made with pitots.

takata

5th Aug 2011, 14:13

A red vertical line is the moment of the Normal to Alternate Law change.
I notice a Pitch Nose Down, right before the Law change.
I can also see now, that the slight Altitude loss was right after the Law change.

Removing, at this point, the "turbulence" effect (the good clue to see its effect is to look at simulated longitudinal axis analysis tables provided), nonetheless you are right about the up/down caused.

Anyway, change of law is due to unreliable airspeed.
The pitch down (at longer term) moment is also due to the reduction of thrust at 0209:58 (Mach 0.80 selected), decrease is about 15% in few seconds.
Altitude is "indicated altitude", as well as speeds, and UAS is causing a loss of "indicated" altitude (but ISIS is barely not affected, about 100 ft). It is obvious when you compare pitch vs V/S curves and altitude altogether: the former increased but altitude indicated change is delayed by 10-15 seconds.

HazelNuts39

5th Aug 2011, 14:23

For whom it may interest: a crossplot of normal load factor (gee) against AoA at entry into stall from the graph on page 45 of the french report #3 - LF vs AoA at stall entry (https://docs.google.com/leaf?id=0B0CqniOzW0rjNGRjMmI1ZGItNTcxZS00MzAwLTgwMTUtZmJiYzh hNTZmM2E5&hl=en_GB).

GarageYears

5th Aug 2011, 14:27

It may be pertinent to the discussion to note that Level D full flight simulators do NOT include sound cues for:

- Ice crystals (hail, yes, one size fits all generally, but smaller ice crystals no)

- Air impact cues from anything other than CAS/Mach related airspeed (i.e. any aircraft velocity that is not horizontal in nature will likely not cause any air impact noise cues.

So an aircraft dropping at 10,000ft/min vertically with at 0 knot CAS would be totally silent in the simulator....

Lonewolf_50

5th Aug 2011, 14:40

Linktrained:
Closing down BOTH engines to flight idle might be the right thing to do - but would FEEL very wrong. Descending at night through a Cb without any clear Airspeed...I know that my Penetration speed should be between 240 and 260 kts, but how can I tell... I must try to keep my wings fairly level if I can...
Yes, descending into a cell is something we are taught not to do in early metro classes.

GerardC: You make some excellent crew points in re "age" not being the end all be all of who is a better choice to have the deck and the con. In regards the assignment of roles and responsibilities, if the Captain tells one pilot "you are in charge" that does not change what sound CRM principles call for. But yes, there is potential for CRM problems.
http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-80.html#post6621097

0210:16, speeds could have been coherent again for a very short time and FDs were back, disapearing almost immediately.
If you are flying the FD, rather than the attitude indicator (is it either or, or is it a blended scan?) that might cause problems if it appears and disappears intermittently.

safetypee: Amen
http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-80.html#post6621211

Altitude is "indicated altitude", as well as speeds, and UAS is causing a loss of "indicated" altitude (but ISIS is barely not affected, about 100 ft). It is obvious when you compare pitch vs V/S curves and altitude altogether: the former increased but altitude indicated change is delayed by 10-15 seconds.
But ISIS doesn't talk to Prims -- am I right about that?

A33Zab

5th Aug 2011, 14:48

a33zab, I don't have the answer, but is it possible, without significant turbulence, to get these g accelerations after N1 was just decreased?

2 h 10 00 > 2 h 10 08, N1 decreases from 100 percent to 84 (or 83) percent (in response to a commanded decrease in Mach)

2 h 10 07 > 2 h 10 18, vertical acceleration varies between 0.9 g and 1.6 g.

2 h 10 23 > N1 begins to increase [from 83 percent].

The thrust changes are part of the normal and longitudinal acceleration
experienced by the accelerometers and refelected by the corresponding graphs.

The -normal accell- (Nz) graph is composed of flight control elevator deflections;
THS trim; roll influences; speedbrake and thrust-changes but also environmental disturbences.

For thrust-changes:

If ∆Nz is the difference between the actual Nz and Nz(1g) and the goal is to maintain a 1g flight:
∆Nz = positive above 1g
∆Nz = negative below 1g
At decreasing thrust and a positive ∆Nz this will result in a less ∆Nz to be
compensated for with elevator.
If the ∆Nz is negative (Nz below 1g) this will result in a higher ∆Nz to be compensated for.

Off course it's the other way around with increasing thrust.

Hard to explain when english is not the native, if anyone feels the need to correct and/or make additions he is most welcome.

SaturnV

5th Aug 2011, 14:51

safetypee, thanks.

GY, perhaps the lack of sound effects in the simulator may explain this somewhat awkward phrasing in the English version,

The background noise changed rapidly around 2 h 09 min 46. This change in the background noise was identified as possibly being characteristic of the presence of ice crystals but did not give rise to any specific comments from the crew, the phenomenon being little known to pilots at the time. The PNF then took the initiative to reduce the Mach towards 0.8 and the engine anti-ice devices were triggered.

Italics mine.

takata

5th Aug 2011, 15:10

Hi HazelNuts39,

Thank you sir, and VERY good work (as usual)
That's exactly what I expected:
https://docs.google.com/leaf?id=0B0CqniOzW0rjNjAzMGRkYmUtZjMwNy00MzBmLWJmMzQtMzIwZjg 2ODYzZDlm&hl=en_GB
Better posting a smaller representation directly for discussion:
http://takata1940.free.fr/CASfromGS.jpg

Airspeed from groundspeed, V/S, windspeed and temperature is shown on this graph: CASfromGS, It is based on wind 45 kt @125 deg, ISA +11 deg C, DFDR data for v/s, altitude and HDG.

The blue dots are Mach from ADR, pink is Mach from GS, wind and v/s, and the green dots show the corresponding CAS.

This is showing where the stall/speed alarm system is flawed in relation to indicated airspeed issues:
"Sensed/indicated" airpseed drops below 60 kt, alarm stops because alpha is NCD. At first sight, it seems fair considering the very remote possibility that an aircraft would still be "flying" at such a low airspeed. Also, IAS went below limits of 30 kt "sensed", hence NCD is displayed on main instruments (only ISIS displays IAS down to 0)

While in reality, this aircraft airspeed was never under 100 kt but stayed in the range of 105-175 kt, where, of course it was not "flying" but "stalling". During about 1 minute, 0211:45 - 0212:45, airspeed was not that far from "flying again" values. The reversal of airspeed tendency happened when engines were set to IDLE.

With correctly interpreted informations (and test pilot skills) this aircraft might have been fully recoverable during this whole minute, as late as 0212:45, and maybe later providing enough altitude remained; Even THS setting is not an issue at such a low airspeed. Elevators are powerfull enough to overide it and trim back; this aircraft is longitudinaly very stable and thrust management could have made the difference for pitching down to "flyable" alpha.

curvedsky

5th Aug 2011, 15:14

http://i31.photobucket.com/albums/c372/fmhshoes/Screenshota.png

Lonewolf_50

5th Aug 2011, 15:22

HN39 or takata:

Does the graph ( http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-80.html#post6621344 ) take into account, or synchronize with, the change in heading to the right over the course of the descent, which would thus vary the airspeed depending upon what winds were at a given level ... or, did you average the winds from what data is known to get the airspeed numbers from ground speed?

GarageYears

5th Aug 2011, 15:32

GY, perhaps the lack of sound effects in the simulator may explain this somewhat awkward phrasing in the English version,

Quote:
The background noise changed rapidly around 2 h 09 min 46. This change in the background noise was identified as possibly being characteristic of the presence of ice crystals but did not give rise to any specific comments from the crew, the phenomenon being little known to pilots at the time. The PNF then took the initiative to reduce the Mach towards 0.8 and the engine anti-ice devices were triggered.
Italics mine.

Agreed. I'm hoping that some of these 'issues' are recognized by the regulators, leading to enhanced requirements for training devices. The technology is available to provide representative cues for such conditions.

The RAeS ICATEE working group is doing some very good work related to upset training requirements, modeling approaches and similar. I am pretty sure many related to that effort are monitoring this thread.

takata

5th Aug 2011, 15:36

Hi Lonewolf,
the change in heading to the right over the course of the descent, which would thus vary the airspeed depending upon what winds were at a given level
It seems to me that HN39 computed the wind direction relative to heading on this reconstruction, see his explanation:
It is based on wind 45 kt @125 deg, ISA +11 deg C, DFDR data for v/s, altitude and HDG.
Change of wind with altitude could be another factor of incertitude, but the end result would provide a good approximation.

HazelNuts39

5th Aug 2011, 15:46

Does the graph ( AF 447 Thread No. 5 (http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-80.html#post6621344) ) take into account, or synchronize with, the change in headingYes it does. I chose a wind speed and direction that produced a match between the calculated Mach and the recorded Mach pior to the airplane going to very large AoA, keeping an eye on the wind recorded on the DFDR. One has to keep in mind that the DFDR wind is obtained by comparing IRU- or GPS-based groundspeed to the ADR-derived airspeed, and also that wind speed and direction may change in the interval shown.

airtren

5th Aug 2011, 15:52

Here is a set of graphs illustrating the association between certain pilot commands, Pitch variation, and Stall Warning OFF/ON/OFF, and the consequences on the confusion in the cockpit.

Unfortunately, the confusion took place during the time window in which the recovery was still possible (35000 ft to approx 6000ft).

(http://farm7.static.flickr.com/6139/6011276723_794400eb0a_b.jpg)http://farm7.static.flickr.com/6139/6011276723_794400eb0a_b.jpg (http://farm7.static.flickr.com/6139/6011276723_794400eb0a_b.jpg)

....

The AF 447 pushed the system to its limits, and two problems surfaced:

a) the STALL WARNING stopped during the STALL, with a confusing effect - the a/c was still in STALL.

b) the STALL WARNING started during the transition from STALL to NON-STALL, with a confusing effect - the pilot commands were ND, or lower Thrust, to take the a/c out from the STALL, and the start of the STALL WARNING meant that the commands were wrong, and so they stopped/reverted the commands.

(http://farm7.static.flickr.com/6139/6011276723_794400eb0a_b.jpg)

GarageYears

5th Aug 2011, 16:35

airten:

But you omit two key parameters from your graphs? Airspeed and AoA.... and since these two are fundamental to the generation of the Stall Warning itself I think you are painting a directed picture.

Take a look at the BEA data and it is clear that the Stall Warning basically follows CAS - the rest is coincidental to my eye at least.

Take just one Stall Warning occurrence - the one centered around 2.14.00 - on page 107 of the English version of the 3rd Report.... and exactly coinciding is a period where airspeed becomes greater than 60 knots. There is clearly some hysteresis around the airspeed value since short periods where CAS exceeds 60 knots don't trigger it, but when the value is there for a 'reasonable' period.

I suspect the problem is that excessive AoA leads to invalid CAS due to pitot characteristics - effectively the dynamic pressure is no longer being read since the inlet aperture is no longer 'inline' with the airflow, and the drain opening is exposed... all in all the problem is a vicious circle, driven by the insane AoA value.

Once IN THE STALL many of the systems necessary to understand the situation are compromised.

Solution = avoid STALLING

DJ77

5th Aug 2011, 16:43

[The PNF] wasn't sure of his own understanding of events.
No wonder he didn't understand, he could not know the PF was not trying to do what he said he would do after the zoom climb: descend.

takata

5th Aug 2011, 16:55

I suspect the problem is that excessive AoA leads to invalid CAS due to pitot characteristics - effectively the dynamic pressure is no longer being read since the inlet aperture is no longer 'inline' with the airflow, and the drain opening is exposed... all in all the problem is a vicious circle, driven by the insane AoA value.
Once IN THE STALL many of the systems necessary to understand the situation are compromised.
Solution = avoid STALLING
Agreed 100%. I'll add that, beside being told to avoid stalling, pilots should be informed of what would eventually happen (as precisely as possible) to their systems if they missed the first part of the drill.

Lonewolf_50

5th Aug 2011, 17:08

Thanks, HN. Winds vary (often considerably) from FL 380 to the surface in both direction and velocity ... so
I chose a wind speed and direction that produced a match between the calculated Mach and the recorded Mach pior to the airplane going to very large AoA,
So far so good
One has to keep in mind that the DFDR wind is obtained by comparing IRU- or GPS-based groundspeed to the ADR-derived airspeed, and also that wind speed and direction may change in the interval shown.

Given the lack of quality in air mass sensor input, that was sort of my point in asking the question. ;)

That said, it only makes a difference if one is trying to sort out whether or not, when the airspeed on your chart increased late in the event, there was a chance to resume flying (how close to unstalling the aircraft might have been with some nose down) .... but that's all after the fact, as the inputs required to do so were not made.

hetfield

5th Aug 2011, 17:09

I'm deeply impressed about all the knowledge and enthuiasm to find out how this accident occurred.

About 1/3 of my career I flew Boeing, 2/3 I drove various Airbusses.

Day after day I'm asking myself, could this happen on a 737, 747, 767, 777.... ?

How far did Airbus go to put three qualified pilots out of the loop?

thx

jimbeetle

5th Aug 2011, 17:31

airtren:
I can also see now, that the slight Altitude loss (if the BEA graph is accurate)
Be very careful on how you interpret very fine differences on the BEA graphs. I believe the slight dip in the altitude one you have referred to over the past few days is a computer/graphics artifact/anomaly. If you look at all of the other altitude graphs they show a smooth curved without that dip.

xcitation

5th Aug 2011, 17:55

@takata/airtren (thanks for your recent posts)

Agreed 100%. I'll add that, beside being told to avoid stalling, pilots should be informed of what would eventually happen (as precisely as possible) to their systems if they missed the first part of the drill.

Good call.
However how do you identify a real stall from a false stall?
Keep in mind that 6-9 months prior to AF447 incident we had a couple of false indication incidents on A330. Were these events fresh in the minds of the AF447 pilots? If so then it might be understandable to ignore stall warning and nose up!

Exhibit A: QF72 (http://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-070.aspx) (extract follows...)

At 1240:28, while the aircraft was cruising at 37,000 ft, the autopilot disconnected. From about the same time, there were various aircraft system failure indications. At 1242:27, while the crew was evaluating the situation, the aircraft abruptly pitched nose-down. The aircraft reached a maximum pitch angle of about 8.4° nose-down, and descended 650 ft during the event. After returning the aircraft to 37,000 ft, the crew commenced actions to deal with multiple failure messages. At 1245:08, the aircraft commenced a second uncommanded pitch-down event. The aircraft reached a maximum pitch angle of about 3.5° nose-down, and descended about 400 ft during this second event.

I believe it had failed PFD, false overspeed warn, false stall warn.

Exhibit B: QF71 (http://www.atsb.gov.au/media/51218/AO2008070_interim.pdf)

safetypee

5th Aug 2011, 18:04

GarageYears, re noise simulation - enhanced requirements for training devices.
I recall that the PSM+ICR report identified a similar problem with poor simulation of engine failure sounds / indications. When all of the ‘relevant’ conditions were identified and programmed in simulation, the ability of a pilot to experience them all, would have taken longer than the total simulator sessions in a career.
Crews could end up permanently in the simulator, in ice, approaching the stall, recovering from upsets, etc, etc. All that might be achieved is avoiding the accident that someone else has just had; to avoid the potential for 'the next accident', the training solutions have to be more generic.

Some critical issue w.r.t. ice crystals are knowledge that the conditions exist, and judgement (risk assessment) in avoiding the hazard. Crews must avoid any complacency encouraged by modern technology, e.g. with a better WXR picture the closer that the ‘legal’ Cb misdistance can be flown. Always add a safety margin, ask what if, and have an 'undo' option' (CtrlZ).
Knowledge and judgement are aspects of airmanship – these are the core (or application) of professionalism. These qualities can be taught using a range of example situations, from basic training through refresher training, but perhaps most of all continuously exercised in daily operations with a ‘learning’ debrief – self improvement – striving to be a professional.

SaturnV, I interpreted “… the phenomenon being little known to pilots at the time …” as implying that the A330 engines had not suffered from ice crystal problems thus the safety threat had not been highlighted (A330 engines true/false?).
However, the ice crystal problem could have been known by all A330 crews based on previous pitot incidents with the appropriate dissemination of information – shared experiences / events. Within this I include the EASA decision to accept a delay in modifying pitots (a practicality) on the assumption that a crew could maintain control (in all foreseeable circumstances) for the duration of a ‘short’ encounter and potential loss of speed displays – enabling opportunity for an operator training action check.
The latter conclusion, could be biased by hindsight, but if we can turn that into foresight (foreseeable circumstances) then we might avoid similarly extreme or remote events. Operators should share safety experiences, and then both management and individuals should consider ‘what if’ for a range of scenarios – reinforcing knowledge, providing a basis for situation and risk assessment – a professional approach to operating in the modern world.

airtren

5th Aug 2011, 18:08

Thanks for your comments.

The graphs I've posted were intended as complementary to the information and the points made by a set of my previous posts, as at the time, I didn't have the graphs available.

The goal of those posts was limited only to the explanation of the relationship between certain elements that are under pilot control, the Stall Warnings and the confusion in the cockpit.

I have not made any claims of completeness on the set of graphs, so it may be the case, that more graphs could be added for more information.

The reasons of WHY the STALL WARNING functioned the way it did was a NON-GOAL, was not in my intention to explain with those graphs, and post.

An analysis of WHY the STALL WARNING functioned the way it did, can be a topic for a different post, and set of graphs. Your suggestions are useful for such a set of graphs, and post.

I think, these clarifications should help with the use of the word "omit" as well.

airtren:

But you omit two key parameters from your graphs? Airspeed and AoA.... and since these two are fundamental to the generation of the Stall Warning itself I think you are painting a directed picture.

Take a look at the BEA data and it is clear that the Stall Warning basically follows CAS - the rest is coincidental to my eye at least.

Take just one Stall Warning occurrence - the one centered around 2.14.00 - on page 107 of the English version of the 3rd Report.... and exactly coinciding is a period where airspeed becomes greater than 60 knots. There is clearly some hysteresis around the airspeed value since short periods where CAS exceeds 60 knots don't trigger it, but when the value is there for a 'reasonable' period.

I suspect the problem is that excessive AoA leads to invalid CAS due to pitot characteristics - effectively the dynamic pressure is no longer being read since the inlet aperture is no longer 'inline' with the airflow, and the drain opening is exposed... all in all the problem is a vicious circle, driven by the insane AoA value.

I could add, that if a STALL is possible with the a/c in a recoverable situation, a reliable, and 100% working STALL WARNING mechanism would increase the chances for the recovery to succeed.

If we consider the causality chain, that the STALL is caused by a "lack of sufficient lift", which is caused by the range of the actual "airspeed" and/or "AoA", it may become clear that if we could sense, or measure directly "the lift", and thus the "lack of lift", then that would be perhaps an additional parameter, that would add to the reliability of the STALL detection/calculation mechanism.

Once IN THE STALL many of the systems necessary to understand the situation are compromised.

Solution = avoid STALLING

Lonewolf_50

5th Aug 2011, 18:21

If we consider the causality chain, that the STALL is caused by a "lack of sufficient lift", which is caused by the range of the actual "airspeed" and/or "AoA", it may become clear that if we could sense, or measure directly "the lift", and thus the "lack of lift", then that would be perhaps an additional parameter, that would add to the reliability of the STALL detection/calculation mechanism.
I respectfully disagree, and mostly in how you phrased that.

Lack of lift typically results in descent.

What happens at stall is the dramatic change in lift generation due to the disruption of airflow at a critical angle of attack.
Before that, lift and drag are generated in a particular manner.
Beyond that, the manner in which the airflow interacts with the airfoil changes. (More turbulent flow, less laminar ... etc)

If you know your AoA, and your critical AoA, then you know how close you are to a change you'd rather avoid.

To measure lift, just what frame of reference are you going to use? :confused:

airtren

5th Aug 2011, 18:22

Agreed 100%. I'll add that, beside being told to avoid stalling, pilots should be informed of what would eventually happen (as precisely as possible) to their systems if they missed the first part of the drill.
Agreed 100%.

I would go even further.

There should be an increased effort to help pilots understand the very basic laws of physics involved, in very simple, and practical terms.

That would make clear the very important causality chain, which forms a logical chain in the systems algorithms, which is not that different than the logic that one should apply mentally.

The training should be clear also about the limitations of the system, and how be able to detect when the system has reached its limitations, and how to use any other available indication for complementing the system and diagnosing the STALL.

"xcitation" mentioned, if I recall correctly, using a bottle of water for attitude indication..... great idea.... maybe add also an Emergency Kit, of very simple tools, which can function independent of anything else....

Neptunus Rex

5th Aug 2011, 18:55

Good call.
However how do you identify a real stall from a false stall?How about, inter alia:

Higher than normal nose (pitch) attitude
+ High rate of descent

They could also have noticed that the sound of the airflow was indicative of low airspeed.

I thnk that PNF had the clues; what a shame he did not take control and act upon them.

3holelover

5th Aug 2011, 19:11

However how do you identify a real stall from a false stall?
By how the aircraft behaves, of course!

It's my sincerest hope that a professional "pilot" would never have to ask that question! I'm presuming those of you asking it are not pilots, because I can't imagine a pilot who could ever not know if he's stalled, PDQ, after the fact. The fact that recent years have shown us that those kind of pilots do exist - even while they earn their Darwin awards, ought to cause us all to have a really good look.... If any pilots reading here have any doubts, have no doubt that you DO need some training.

peefactor

5th Aug 2011, 19:20

Apologies if I mention things that were covered already.

(*I speculate*) Could the PF's initial response to pitch up have been to regain his original altitude of FL350? - Perhaps his altimeter showed a gradual loss in altitude as blockage occurred?

(as happened in previous events. See pg48 and pg51 of the following document: http://www.bea.aero/docspa/2009/f-cp090601e2.en/pdf/f-cp090601e2.en.pdf (http://www.bea.aero/docspa/2009/f-cp090601e2.en/pdf/f-cp090601e2.en.pdf))

The PNF's action of switching the F/O displays to ADIRU 3 info seems to also suggest he felt ADR2 was less reliable.

Later on, after the captain is in the cockpit:

2 h 12 min 15 to 2 h 12 min 19
CAP: Là je sais pas là ça descends
There I don't know, there it's going down

His comments coincide with the AIR DATA and ATT-HDG selector being positioned to 'CAPT on 3'. Seems like a lot of confusion in the cockpit about what is happening with the altitude. The airplane is pitched nose-up, by this stage the PF claims to no longer have any V/S indication, and there continues to be doubt as to whether the airplane is gaining or losing altitude.

2 h 12 min 27
PNF: Tu montes ...
You're going up ...

PNF: Tu descends descends descends descends
go down go down go down go down

2 h 12 min 30
PF: Je suis en train de descendre là?
Am I going down?
(Pardon my French, but could the 'là' be the PF referring to PFD1 or the ISIS? As if to say "those instruments there say I'm descending???"

PNF: Descend !
Go down

2 h 12 min 32
CAP: Non tu montes là
No you're going up there
(WHERE does it show them climbing??? I am not so sure he is referring to pitch attitude)

2 h 12 min 33
PF: Là je monte okay alors on descend
There I'm going up ok so let's go down
(Once again - what is indicating to him that they are going up?)

There are only two things which I can think of which indicate up and down in an airplane (excluding the V/S indicator).
1) Pitch Attitude (in which case the whole discussion of up and down is in reference to attitude).
2)Altimeter information (in which case one of them is indicating an increase or constant altitude, while the other(s) indicate a decrease in altitude.

I am baffled by what could have been happening, and as the ADR2 data is not recorded by the FDR it leaves us wondering whether it was behaving in a similar fashion to ADR1 and 3, or doing something else. Otherwise...how could there be so much discussion about whether one is climbing or descending?!?

I strongly believe the captain's comment was in reference to this conflict of information:

2 h 12 min 44
CAP: (…) C’est pas possible
It's not possible

And I would be inclined to say the same - I don't think it's possible for one ADR to somehow be frozen or to be indicating an increase in altitude. Nor do I know whether it's possible for IR2 to be displaying different attitude information compared to IR1 and 3. But the entire talk of climbing/descending leads me to envision such scenarios.

As a final point - I do not doubt the experience or professionalism of the crew. I believe they did their best with the information that was presented to them, and I don't think it was as simple as the PF simply being 'behind the airplane' and not noticing where he was pointing the airplane - it's possible, but I imagine there's more pieces missing to this puzzle. Nor do I think he was chasing the intermittent FD bars. I think a pilot with his experience on the Airbus would know not to follow the FD bars blindly - it would serve no purpose in such a situation and I'm willing to bet he was aware of that.

PS - If it wasn't mentioned already, the airplane switched to Alternate 2 - meaning roll control was DIRECT. Maybe this contributed to his 'over controlling' in roll.

Welsh Wingman

5th Aug 2011, 19:32

DJ77

Quite - hence my unease at the entire SS concept (#1535)

Neptunus Rex

Agreed re: PNF. If he had seen PF's control inputs between FLT350 and FLT380, he would have been there.....

Neptunus Rex

5th Aug 2011, 19:39

He did not need to see the control inputs...he could see the results.

Neptunus Rex

5th Aug 2011, 19:44

peefactor
3. But the entire talk of climbing/descending leads me to envision such scenarios.The reaction on their inner ears should have told them that they were in a rapid descent. Plus, the Captain should have noticed the aircraft deck angle as he walked, or rather climbed, to the cockpit.

Airmanship again.

Welsh Wingman

5th Aug 2011, 19:52

I am not talking objectively as to what should have happened/been triggered. I am talking subjectively as to what actually happened that particular night, based on what has been disclosed so far (shortly after his rest break, in the early hours). PNF was almost there, and just needed one or two more clues, and that is a separate question to what he should have needed under a proper training environment that properly equipped both pilots to deal with the situation they encountered (but then modern planes fly themselves and pilots are just a cost that reduces shareholder dividends, or so too many senior line management believe....).

xcitation

5th Aug 2011, 19:56

Neptunus Rex,
How do you know which instruments are valid and which are bogus.
You might only have seconds to figure it out!

I recommend you read the QF72 interim factual 1, to see what the Quantus captain said. He was not certain of the "varacity" of all of them. Fortunately he had visual + good weather so the situation was less confusing than AF447.

QF72 interim factual 1 (http://www.atsb.gov.au/media/51218/AO2008070_interim.pdf), an extract.

The flight crew reported that the weather was fine and clear and there had been no
turbulence during the flight. At about 1239, the first officer left the flight deck for a
scheduled rest break. The second officer then occupied the right control seat.
At 1240:28, the autopilot disengaged. The crew reported that there was an
associated ECAM3 warning message (AUTO FLT AP OFF) and that they also
started receiving master caution chimes. The captain took manual control of the
aircraft using the sidestick. He reported that he attempted to engage autopilot 2 and
then autopilot 1, but neither action was successful.4 The flight data recorder (FDR)
showed that, during this period, the aircraft’s altitude increased to 37,200 ft before
returning to the assigned level.
The crew reported that they cleared the AUTO FLT message from the ECAM. They
then received a NAV IR1 FAULT message on the ECAM.5 The crew were also
receiving aural stall warning indications at this time, and the airspeed and altitude
indications on the captain’s primary flight display (PFD) were also fluctuating.
Given the situation, the captain asked the second officer to call the first officer back
to the flight deck.
At 1242:27, while the second officer was using the cabin interphone to ask a flight
attendant to send the first officer back to the flight deck, the aircraft abruptly
pitched nose-down. The captain reported that he applied back pressure on his
sidestick to arrest the pitch-down movement. He said that initially this action
seemed to have no effect, but then the aircraft responded to his control input and he
commenced recovery to the assigned altitude. The aircraft reached a maximum
pitch angle of about 8.4 degrees nose-down during the event, and a maximum g
loading of -0.80 g6 was recorded. The aircraft descended 650 ft during the event.
The flight crew described the pitch-down movement as very abrupt, but smooth. It
did not have the characteristics of a typical turbulence-related event and the
aircraft’s movement was solely in the pitching plane. They did not detect any
movement in the rolling plane.
During the initial upset event, the second officer activated the seatbelt sign to ON
and made a public address for passengers and crew to return to their seats and
fasten their seatbelts immediately.
The flight crew reported that, after returning the aircraft to 37,000 ft, they
commenced actions to deal with multiple ECAM messages. They completed the
required action to deal with the first message (NAV IR1 FAULT) by switching the
captain’s ATT HDG (attitude heading) switch from the NORM position to CAPT
ON 3 position, and then cleared that message. The next message was PRIM 3
FAULT.7 The crew completed the required action by selecting the PRIM 3 off,
waiting 5 seconds and then selecting it on again.
At 1245:08, shortly after the crew selected PRIM 3 back on, the aircraft
commenced a second uncommanded pitch-down event. The captain reported that he
again applied back pressure on his sidestick to arrest the pitch-down movement. He
said that, consistent with the first event, that action was initially unsuccessful, but
the aircraft then responded normally and he commenced recovery to the assigned
altitude. The aircraft reached a maximum pitch angle of about 3.5 degrees nosedown,
and descended about 400 ft during the second event. The flight crew
described the event as being similar in nature to the first event, though of a lesser
magnitude and intensity.
The captain announced to the cabin for passengers and crew to remain seated with
seatbelts fastened. The second officer made another call on the cabin interphone to
get the first officer back to the flight deck. The first officer returned to the flight
deck at 1248 and took over from the second officer in the right control seat. The
second officer moved to the third occupant seat.
After discussing the situation, the crew decided that they needed to land the aircraft
as soon as possible. They were not confident that further pitch-down events would
not occur. They were also aware that there had been some injuries in the cabin, but
at that stage they were not aware of the extent of the injuries. At 1249, the crew
made a PAN8 emergency broadcast to air traffic control, advising that they had
experienced ‘flight control computer problems’ and that some people had been
injured. They requested a clearance to divert to and track direct to Learmonth, WA.9
Clearance to divert and commence descent was received from air traffic control.
Figure 1 shows the track of the aircraft and time of key events.

Following the second upset event, the crew continued to review the ECAM
messages and other flight deck indications. The IR1 FAULT light and the PRIM 3
FAULT light on the overhead panel were illuminated. There were no other fault
lights illuminated. Messages associated with these faults were again displayed on
the ECAM, along with several other messages. The crew reported that the messages
were constantly scrolling, and they could not effectively interact with the ECAM to
action and/or clear the messages. The crew reported that master caution chimes
associated with the messages were regularly occurring, and they continued to
receive aural stall warnings.
The captain reported that, following the first upset event, he was using the standby
flight instruments and the first officer’s primary flight display (PFD, see Appendix
A) because the speed and altitude indications on his PFD were fluctuating and he
was unsure of the veracity of the other displayed information. After the second
upset event, he had observed that the automatic elevator trim was not functioning
and he had begun trimming the aircraft manually. He later disconnected the
autothrust and flew the aircraft manually for the remainder of the flight.
The flight crew spoke to a flight attendant by interphone to get further information
on the extent of the injuries. The flight crew advised the cabin crew that, due to the
nature of the situation, they did not want them to get out of their seats, but to use the
cabin interphones to gather the information. At 1254, after receiving advice from
the cabin of several serious injuries, the crew declared a MAYDAY10 and advised
air traffic control they had multiple injures on board, including a broken leg and
some cases of severe lacerations.
The crew continued attempts to further evaluate their situation and, at 1256,
contacted the operator’s maintenance watch unit11, located in Sydney, by
SATPHONE to seek assistance. There were several subsequent communications
during the flight between the flight crew and maintenance watch, who advised that
the various faults reported by the crew were confirmed by data link, but that they
were not able to diagnose reasons for the faults. During one of the conversations,
maintenance watch suggested that the crew could consider switching PRIM 3 off,
and this action was carried out. This action did not appear to have any effect on the
scrolling ECAM messages, or the erratic airspeed and altitude information.

vanHorck

5th Aug 2011, 19:56

It has been said before but I d like to add my voice to this opinion. English is a much more factual language then French.

The French language is in my humble opinion too ambivalent to be used in a factual environment like a cockpit in distress.

Là is such a word which could be used in the sense of indicating a position (there) or a given time (then), and there are more.

Perhaps there has been no misunderstanding between pilots on the deck about the intentions of whoever spoke in this specific case. I do not feel qualified to judge this, despite having been raised in part in French, but others should.

I realize some French natives may object to my humble opinion, French are notoriously protective of their language, as it is a fundamental part of their cultural heritage (just think of the French laws requiring French broadcasting stations to broadcast a certain % of music in French), but I do think the discussion should be had.

Time for a quick exit....

Lonewolf_50

5th Aug 2011, 20:11

xcitation (QF72)
The crew reported that master caution chimes associated with the messages were regularly occurring, and they continued to receive aural stall warnings.
If the conventional wisdom among A330 pilots, or some A330 pilots, was that with UAS/Pitot problems, stall warning is generally spurious ... that might explain the reaction to stall warnings not being what we'd expect.

The cry of "wolf," or the cricket chirp of "wolf" could be a case here.

Welsh Wingman

5th Aug 2011, 20:14

Definitely a cricket chirp:ok:

xcitation

5th Aug 2011, 20:49

3hole...
By how the aircraft behaves, of course!

It's my sincerest hope that a professional "pilot" would never have to ask that question! I'm presuming those of you asking it are not pilots, because I can't imagine a pilot who could ever not know if he's stalled, PDQ, after the fact. The fact that recent years have shown us that those kind of pilots do exist - even while they earn their Darwin awards, ought to cause us all to have a really good look.... If any pilots reading here have any doubts, have no doubt that you DO need some training.

We do not all have your "Chuck Yeager" skill level. The rest of us non-aces require extensive training.

This was a stall in an a/c with degraded instruments, ALT LAW, no visual in chop. Not a trivial case. The inexperienced PF did try stick forward however a/c still stays nose up no response, as elevator is at -30 deg due to full THS! So behaviour is bizarre and only explained if you have a full understanding of the situation in 60 seconds. Even then you would be faced with stall recovery - also not trained for and not trivial.

Bus pilots have stated that ALT LAW behaves like no other a/c you have flown! So if you have not tried it don't you think it is a bit presumptive/over simplistic to "see how a/c behaves".

Even the QF72 CAP with the help of experience, day time, normal law, good weather still doubted varacity of all his instruments. Fortunately he could correctly ignore his stall warnings. IMHO given the details of AF447 incident it was a difficult and exceptional situation.

CONF iture

5th Aug 2011, 20:50

It seemed normal to me and no, BEA would not comment something "normal" without good reasons to do so.
I'm afraid, takata, you will have to explain me what's "normal" in it ... ?
I am very curious of that kind of normality.

BTW, is the AoA1 value stuck at 2.1 deg part of the normality too ?

Following, something I'm not sure to understand - How things work - What's the logic behind ?
Maybe A33Zab could explain ... Thanks.

http://i45.servimg.com/u/f45/11/75/17/84/wiz_pi11.gif (http://www.servimg.com/image_preview.php?i=108&u=11751784)

Black Sheds

5th Aug 2011, 20:51

As an electronic engineer and pilot of 50 hours, before a pacemaker intervened, I an astonished that all the blame is being put on the pilots and “lack of training”. The cause of the accident is absolutely plain. The automatic systems and glass cockpit completely failed the pilots by providing erroneous and variable indications. With a carefully designed back-up of dependable instruments such as gyros and inertial navigators, and others, pilots would not be without believable data. When the automatics fail catastrophically, as in this case, they should be cut out. The so called stall would never have been believed and subsequently would not have been turned into a real stall. The fault lies with (ALL) modern aircraft design.

airtren

5th Aug 2011, 20:56

Lonewolf

I've expressed an idea, in a quick post ... and you're nit picking on that.:)
giving me the opportunity to muse on semantics....

I could say that I disagree with you, based on how you describe the "descent" as being caused by a "lack of lift".

I could say, a "descent" is caused by "a gradual diminishing of lift" not a "lack of lift". ;)

"Lack of lift", means (to me) "absence of lift". and thus "fall".
You called it "drastic change in lift".... well, yeah,.... it is a change that results in "lack of lift"....

But we can also say that "fall", is a "descent", with the qualifier "at high or very high vertical speed".... :). That's BEA's language?

So, we can say, that the "stall/lack of lift" is a subset of the larger set which is "change of lift", which includes the other subset, which is the normal "descent/gradual change of lift".

For that AoA, isn't that bottle of water that "xcitation" mentioned a genial idea????

I respectfully disagree, and mostly in how you phrased that.

Lack of lift typically results in descent.

What happens at stall is the dramatic change in lift generation due to the disruption of airflow at a critical angle of attack.
Before that, lift and drag are generated in a particular manner.
Beyond that, the manner in which the airflow interacts with the airfoil changes. (More turbulent flow, less laminar ... etc)

If you know your AoA, and your critical AoA, then you know how close you are to a change you'd rather avoid.

To measure lift, just what frame of reference are you going to use? :confused:

3holelover

5th Aug 2011, 21:01

@xcitation
Worry not, sir. I'm no Chuck Yeager. I don't even fly any more. But I'm certain that a stalled aircraft behaves just like a stalled aircraft, and ALL pilots should know that behaviour. In this case you can clearly see in the traces the A/C was indeed behaving just like a stalled aircraft. Keep on training!

ChristiaanJ

5th Aug 2011, 21:11

It has been said before but I d like to add my voice to this opinion. English is a much more factual language than French.I totally agree with your remarks.... French is NOT a technical language.
Speaking as another Dutchman, who's spent half his life in France (aircraft industry), but with English as the 'family' language at the same time (long story, and not really 'on topic' here).

Welsh Wingman

5th Aug 2011, 21:24

Yes and no.

Not easy, not by any means, but troubling that they did not appear to diagnose the stall to the very end (unless you interpret the CDB's "impossible" remark). There were plenty of hurdles, e.g. the 60kt alarm "cut off" and no AoA indication (and the PF and PNF were probably receiving very different information at times), but also plenty of clues - pitch/attitude, trim (THS position), buffet and the VSI plummeting downwards. And the audible stall alarm, intermittently.

What worries me more is whether, unless the stall had been prevented in the period after A/P disconnect and reversion to ALT law, this crew were trained to recover from such a stall by hand flying and even with FLT380 to play with? As I have said previously, I believe PNF was close to diagnosis. From what has so far been disclosed, I still wouldn't bet my mortgage (if I still had one) on their recovering and that poses a lot of questions for the industry.....

Re: QF72. I just blame the US Navy! I remember flying near "Harold Holt" on the run down from Kuala Lumpur to Perth in the early-80s and strange things happening to my avionics (that was a 747, not an AB).......

HazelNuts39

5th Aug 2011, 21:29

For me the previous two graphs (thanks for your comments) were just 'stepping stones' to the graph I was working on: AF447 cL-alpha prior to and post-stall (https://docs.google.com/leaf?id=0B0CqniOzW0rjNGU3YzFlNzItMzAwNi00MTRkLTg4OTEtZmExNmF hNWE1MDY4&hl=en_GB).

TurboTed

5th Aug 2011, 21:32

Something like this stuck to a flat surface would tell you if the plane was pointing up/down and whether the wings were level or not:

Caravan, Motorhome Universal Triangular levelling device Spirit Level.: Amazon.co.uk: DIY & Tools

There are bigger/more expensive versions too, with digital readouts and 0.1degree accuracy. No computer needed. How about 2 of these:

Digital Angle Gauge / Protractor / Inclinometer / Bevel Box WITH LEVEL BUBBLE & HOLD BUTTON + Leather Pouch & Batteries: Amazon.co.uk: DIY & Tools

DozyWannabe

5th Aug 2011, 21:39

The automatic systems and glass cockpit completely failed the pilots by providing erroneous and variable indications.

Really? As far as I can see, only the instruments related to pitot data could be considered unreliable, that is until the point that the AoA became so extreme that various anomalies that would have messed up any display reliant on air data, mechanical or digital.

With a carefully designed back-up of dependable instruments such as gyros and inertial navigators, and others, pilots would not be without believable data.

Where do you think the data in a glass cockpit comes from? The glass cockpit instruments are *driven* by gyros and inertial sensors, and they were telling the truth the whole way down.

OK465

5th Aug 2011, 21:41

From post #1625:

Bus pilots have stated that ALT LAW behaves like no other a/c you have flown!

To set the record straight, some "Bus pilots" have not made this statement.

Rob21

5th Aug 2011, 21:42

It seems to me that the PNF was giving instructions to the PF based on indications he had, and PF didn't.
It also seems to me that the PF had his own indications, but was not trusting them, they were too crazy, confusing.
It also seems to me that the Captain was puzzled by what was going on with both side indications.

On the PF's side one thing (or nothing sometimes), on the PNF maybe just the altimeter worked kinda properly.

So it makes sense to me that the PNF did not have all the information necessary to hold the plane (i.e. Attitude Indicator), so he kept telling PF what to do.
On the other hand, PF had other kind of information, which PNF didn't.

Imagine the Captain's situation, he can't believe in his eyes. What he is seeing is not possible.

What is he seeing?
We don't know, many parts of the CVR are missing (to us).

I am not suggesting that a "coverup" is going on, but lets suppose BEA has an "inclination" to suggest that the pilots could have saved the situation. If the conversation between the 3 pilots would show they were confused, why show just part of the conversation?
Why show only the "confused" part?

All three pilots didn't have the slightest idea of what was going on, and is very hard to believe they only lost airspeed and AP.

Maybe when we see the full CVR trancript...

funfly

5th Aug 2011, 21:49

All the talk of what is a stall etc. and how us pilots 'know' exactly what it is like to be in a stall....What we don't know is if we would be able to decide if we were in a stall or a dive should we be in a cockpit with no outside visibility or working instruments and all we knew was that we were descending at a rate where we could be almost in zero g.
That may well be the difference between our experiences of stalling and their experiences on the day - experiences that no simulator training would have been able to reproduce.

takata

5th Aug 2011, 22:06

The French language is in my humble opinion too ambivalent to be used in a factual environment like a cockpit in distress.
Well sure. Only native anglophones /[insert your own culture], preferably those raised near [insert your place], should be recruited to fly modern jets. Many languages and cultures are unable to provide the mandatory level of efficiency required. People tends to say words that, once translated into English /[ or whatever], doesn't make enough sense to me. Consequently, such talks should be banned from cockpits and considered unsuited for high-technological environements due to their intrinsic flaw at being fully understandable by me.

Such statement do not surprise me. I could say exactly the same about English/[insert your own langage] forms but I'm not so ethnocentric.

What cause such a distorsion about the exact meaning of those words is primary due to several factors [many that a non native, whatever his proficiency level, would never catch in a lifetime]:
1. We are not listening at what they said, it is not complete and we are reading it from a poorly made transcription. Add the fact that, for the majority of the readers here, you are reading it from a poorly made translation of this poorly made transcription.

2. French talk is quite different from French written forms. Without its prosodie - rythm, tone, emphasis, etc. - it may be clearly ambiguous from the direct transcription. Hence, without listening the original conversation in integrality, I'm a bit clueless about their talks referential. Some of the referential is also lost by not seeing them, because there is many "shortcuts" used for talking. In fact, the ammount of informations they had, when talking to each others, is not part of this transcription. I'm sure that accessing to the original record would clear many ambiguities.

3. I suppose that BEA, at this stage, released the minimal work on CVR voluntarily; only people which had heard the CVR would have a right idea of what happened in the cockpit. There was strictly no effort made to make it really meaningful in English version -it is called a litteral translation: emphasis is put on words, without bothering about sense.

4. Last but not least, making sense is not a question of langage, it is a question of discipline. What I'm able to infer from the first reading is a serious lack of crew discipline. No further comment is needed about it.

Alber Ratman

5th Aug 2011, 22:21

Takara, do you mean that flight deck crew indisipline was a factor in your interpretation of what you have read (in your native tounge I would hope?) It would not have been the first accident that ever happened with such an enviroment (the Korean 747 crash at Stansted springs to mind), and it wouldn't be the last..

promani

5th Aug 2011, 22:25

I have to put my ten cents worth in here. Takata is right IMHO, about French. The same applies to all languages that I have encountered, including English. No way can anyone, who has not heard the CVR, can arrive at an accurate interpretation of what was said. Also people gesture with their hands, arms ,face and head, when talking. The "Continentals" being the greater users of their bodies when communicating.

ChristiaanJ

5th Aug 2011, 22:26

takata,
That's what I tried to say, but a lot less clearly....

MountainWest

5th Aug 2011, 22:28

Good thought, but unfortunately these are also driven by "G" forces. They are not accurate in a turn, during acceleration, etc.

Welsh Wingman

5th Aug 2011, 22:42

Other forums can deal with the Seven Years War of 1756-63 and the rise and hegemony of the English language (even as spoken by our American cousins "over the pond") as the "global" language(!), so let's focus on Takata's "discipline" good point (well made). AF had 3 hull losses in 9 years, each where there have been not insubstantial CRM issues to varying degrees. But I cannot see where the use of the French tongue per se (as opposed to the over colloquial use of any language) has ever been a contributing factor to the hull loss (as opposed to a nuisance to non-French speakers in air accident reports!). If either the PF or PNF on AF447 had diagnosed the problem, it would have been conveyed to the other and to the CDB. There is nothing in the CVR so far disclosed, any more than anything in their respective flying history and experience, to suggest other than F/O 37 should have been PIC in CDB's absence (as PNF in LHS). I am really struggling to get "my head around" the entire "relief" pilot regime that was in force. I can see the benefit of a CPT having the discretion to select a PIC, e.g. a longserving F/O unsuitable to ever become a CPT or a less experienced but still experienced "high flyer" of a F/O heading upwards, but I can see nothing to indicate why F/O 32 should not have been under F/O 37. The latter should not have been "nagging", as one post (I think accurately) described his instructions to the PF.

takata

5th Aug 2011, 23:04

do you mean that flight deck crew indisipline was a factor in your interpretation of what you have read (in your native tounge I would hope?) It wouldn't have been the first accident that ever happened with such an enviroment (the Korean 747 crash at Stansted springs to mind), and it would be the last..
After my first reading (yes, it's my mother tongue), I was quite astonished that a supposed "professional" crew would behave like that in such a critical situation. Good professionnals may use sometime a "relaxed" way of communication, but if the situation would become critical, they should instinctively revert to their discipline of communication.

I'm also quite sure that the CVR transcript was expurgated from many slang forms which should have been added to several sentences heard. PF sounds like a teenager, not a 32 years old fully qualified A330 driver. Captain said almost nothing, or it was cut in report.

BEA also inserted numerous leads (flight related) that, once put together, are showing a very same pattern all along this flight. Going further into this chapter, at this point, would not help the BEA as full cooperation with the company is needed in order to conduct this investigation to its end.

A33Zab

5th Aug 2011, 23:06

Hi Conf,

This discrete represents the source of the vertical speed indication on PFD.

From the report: page 94 (English version)

@12:11:45
---
The vertical speed is no longer calculated by the IR (Inertial reference)
but by the ADR.
It is about -10,000 ft/min.

and confirmed by FCOM.

FCOM
1.31.40

INDICATIONS ON PFD

VERTICAL SPEED:

The displayed vertical speed information is normally based on both inertial and barometric data.
If inertial data is not available, it is automatically replaced by barometric information.
In this case, the window around the numerical value becomes amber.

That will raise another question, why was IR V/S not available?
was it related to:
02:13:14 - .1/FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2 (1FP2),HARD
and this fault message related to disapperance of FPV?

The presence of the “FLAG FPV ON PFD CAPT (F/O)” message indicates that TRK-FPA
(Flight Mode Annunciator) mode was selected by the crew during minute 2 h 11, but that the
FPV was unavailable (see interim report 2 for details on the conditions of availability). Based
on a study of the other relevant parameters it may be concluded that the FPV was selected between
2 h 11 min 48 and 2 h 11 min 54.

jcjeant

5th Aug 2011, 23:10

Hi,

TurboTed
Something like this stuck to a flat surface would tell you if the plane was pointing up/down and whether the wings were level or not:
Think again :)
At 2min10

‪Stopped engine aerobatics‬&rlm; - YouTube

spagiola

5th Aug 2011, 23:25

2 h 12 min 44:
CDB: (…) C’est pas possible

There has been some discussion concerning what the captain was referring to when he said this. As a further note on language (this is becoming quite a theme, here), please note that "c'est pas possible" could also quite easily be a generalized expression of frustration. For example, if you arrive at the movie theater only to be told that the movie is sold out, you may well exclaim "c'est pas possible!" It doesn't mean you think that it's actually impossible that the movie is sold out, or that you don't understand how it came to be sold out.

I'm not saying this is the case here. Without hearing how the words were said, it's impossible to conclude anything either way. I just wanted to raise this as a possible option before people get too far into speculating which instrument he might have been looking at.

takata

5th Aug 2011, 23:30

That will raise another question, why was IR V/S not available?
was it related to:
02:13:14 - .1/FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2 (1FP2),HARD
and this fault message related to disapperance of FPV?
FPV ECAMs fault are due to their selection and rejection (they were unselected before this point) because airspeed was < 60 kt.

It looks like CONF-iture doesn't read (or believe in) BEA reports; this fault was explained and very understandable considering that pressure altitude, barometric vertical speed and true airspeed were altogether affected by high alpha and unvalid dynamic pressure resulting. In fact, it was a triple IR rejection of ADRs - this fault was reported three times, one by each IR, but consolidated into one single ACARS:

Page 38, report #2.

ADIRU2 (1FP2) (2 h 11)
ATA: 341234
Source: IR2
Identifiers: *EFCS1, IR1, IR3
Class 1, HARD

This message was generated by IR 2. For an ADIRU of this standard, it means that the IR considered that the three ADRs were invalid, that is to say that at least one of the three parameters was invalid (SSM status not NO) amongst pressure altitude, barometric vertical speed and true airspeed. As soon as the third ADR is rejected, the IR generates a message pointing to its ADIRU. If one of the IRs considers the three ADRs as being invalid, this must also be the case for the other IRs. It is therefore logical that, in parallel with this ADIRU 2 message generated by IR 2, an ADIRU 1 message was generated by IR 1 and an ADIRU 3 message by IR 3, which would explain the presence of the latter amongst the identifiers.

The fact that EFCS1 was present amongst the identifiers preceded by an asterisk indicates that EFCS1 had at least generated one class 2 message, perhaps followed by a class 1 message. There are too few elements available to determine precisely what the presence of EFCS1 amongst the identifiers means. Nevertheless, it is possible to state that it concerns a rejection of ADR by at least two PRIMs. It has not been possible at this stage to understand why EFCS2, the clone of EFCS1, is not an identifier.

Welsh Wingman

5th Aug 2011, 23:35

takata

5th Aug 2011, 23:52

It's just the most tantalising limited-release CVR comment, at FLT200. The reality is that the BEA, even with access to the full FDR/CVR, may never know what the CDB meant by that remark (and the possibilities are endless to speculate over).http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/worry.gif
As the exact quote is:
CDB: (…) C’est pas possible
One knowing what was "(...)", added to his tone, would have a very good idea of what the captain really expressed. But, I'll refrain from proposing to change this expression into something meaningful... as some could complain to JT about my langage.
Just note that Spagiola remark is by far the best proposal with all clues on hands.

A33Zab

6th Aug 2011, 00:28

Hi Takata,

Well in fact this question was raised by me.......and I did read the full reports but maybe I did missed this one.

Ok, try to formulate it another way.......for what reason could Inertial Data be not available?
IR part of ADIRU can operate normal even if ADR is providing unreliable information.

Quote:
FCOM
1.31.40

INDICATIONS ON PFD

VERTICAL SPEED:

The displayed vertical speed information is normally based on both inertial and barometric data.
If inertial data is NOT available, it is automatically replaced by barometric information.
In this case, the window around the numerical value becomes amber.

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

Alber Ratman

6th Aug 2011, 00:34

Takana, thank you for your views in regards to you native understanding of the CVR Transcript. You have (as the English quotation puts it) hit the nail on the head. Regardless of faults in the design philosophy of the aircraft (and the BEA have hinted them in their recomendations as well as AD's that EASA have introduced since), a servicable aircraft seems to have been lost with all souls due to a massive failure of CRM IMHO. While I will not take the view that the flight crew were not totally professional (because I did not know them and cannot comment as such), I would wager most Captains in such a situation would be have been more self preserving that what the CVR transcript leads to have been the actions of Captain Dubois in not taking control, especially when the PF was unsure of his actions. He did have the time (and height) to do so. Air France may continue to defend their crews most vigiously and that is only to be expected and conmmended as an employer. However the accountants heading the company must realise that AF's standing in the world is only upheld if they are fully free to ensuring every facet that caused AF447 to smash into the ocean is investigated, independantly reviewed and actions taken to prevent such events ever occuring in this manner again, to anybody.

Welsh Wingman

6th Aug 2011, 00:47

Hi Takata

"(...)" itself may never be known (as opposed to deliberately omitted, and even then it could easily be ambiguous).

There is a widespread misconception that CVRs are easy to decipher. They most definitely are not. The hardest day's work that I ever did (and certainly the most emotionally draining), was not landing my Buccaneer on a flight deck or landing a 747 on various runways where ideally wide bodied jets should not go anywhere near (thankfully fewer in number these days), but a day at the AAIB helping investigators to make sense of what a F/O that I knew had said shortly before his death on duty.

It's hard work for the BEA, even with input from close colleagues of the deceased flight crew.

The cockpit issues you refer to are troubling, border line the other extreme to the CRM Van Zanten/Meurs issues.

takata

6th Aug 2011, 01:42

Ok, try to formulate it another way.......for what reason could Inertial Data be not available? IR part of ADIRU can operate normal even if ADR is providing unreliable information.
What reason, what reason... would you like a +/- 10,000 ft treshold exceeded for inertial vertical speed? It is always the same reason, a designed parameter exceedance.

A baro inertial loop is integrated in the inertial V/S computation to bring the stability in time of the air data (no drift like inertial data). Degraded data: When the inertial vertical speed is not available, the baro vertical speed is automatically displayed. Failure : In case of vertical speed failure, the scale is replaced by a vertical speed flag.

In case of excessive vertical speed, the digital and analog indications
become amber. Excessive V/S when :
- V/S > 6000 ft/mn or V/S < - 6000 ft/mn,
- V/S < -2000 ft/mn below 2500 ft Radio Altimeter,
- V/S < -1200 ft/mn below 1000 ft Radio Altimeter.

But It looks to be set at +/- 10,000 ft in order to show a degraded status.

takata

6th Aug 2011, 01:56

"(...)" itself may never be known (as opposed to deliberately omitted, and even then it could easily be ambiguous).
Sure, but this one was understood and deliberately omitted... and I may understand why.:ooh:
See legend:
(…) Words or groups of words not relevant to the conduct of the flight
(*) Words or groups of words not understood

IMO, it was relevant for understanding what the captain expressed.

jcjeant

6th Aug 2011, 02:23

CDB: (…) C’est pas possibleI do think I am right in saying that the captain words should be an exclamation indicating disbelief or surprise to see something beyond his understanding or completely abnormal or completely wrong

So in the (...) can be the words
Mais ....
Putain ....
Merde ...
Bon dieu

So .. full speculation .. so many open possibilities ..

takata

6th Aug 2011, 03:51

Hi jcjeant,
I do think I am right in saying that the captain words should be an exclamation indicating disbelief or surprise to see something beyond his understanding or completely abnormal or completely wrong
Spagiola's explanation of expressing a sentiment of extreme frustration close to anger, was much better than yours. That's the reason why it is usually introduced by a volley of profanities; some of those words you quoted are sometime all used at once for good effect : n... de d... ! de p... de b... de m... ! c'est pas possible !

please note that "c'est pas possible" could also quite easily be a generalized expression of frustration. For example, if you arrive at the movie theater only to be told that the movie is sold out, you may well exclaim "c'est pas possible!" It doesn't mean you think that it's actually impossible that the movie is sold out, or that you don't understand how it came to be sold out.
Disbelief is not the primary sentiment, as in fact, one will clearly acknowledge that the situation is real but very frustrating.

jcjeant

6th Aug 2011, 04:28

Hi,

Spagiola's explanation of expressing a sentiment of extreme frustration close to anger, was much better than yours. When you don't understand something ... you can be frustrated a max .. certainly if you (or think) know many things ...
So .. c'est pas possible can be an exclamation caused by something beyond his understanding
Anyways all is open .. and again .. this must be not important in the cause of the accident
The most important words are "j'ai les commandes" and the actions immediately following.
If those actions can be explained by other thing than a "pilot error" ... maybe this accident will bring some (new) progress for the aviation safety

peefactor

6th Aug 2011, 04:31

ADR Switching:

From my experience, I've noticed the information isn't presented instantaneously but rather 'scrolls' to the particular value.

At least this is what I've noticed with normal working ADRs, when using the ADR switch on the 320 family.

Now for their situation, having the AIR DATA switch placed to 'CAPT on 3' after the captain entered the cockpit, would revert the PF's altimetry information back to ADR2 - which, if in the (highly unlikely but possible?) event that one or both the F/O Static Ports were blocked - I imagine would start 'scrolling' UP indicating a climb (to the original altitude at the time of blockage). This of course would be highly confusing, especially coupled with the lack of V/S information on the PF side, and would certainly hinder their progress in recovering the situation.

(Once again - we do not have the ADIRU 2 information as it is not recorded by the FDR. Unfortunately I think that information would be the key to understanding the PF's actions).

Anyone have more experience with this ADR switching 'scrolling' aspect?

BluJet

6th Aug 2011, 06:55

Some people here critizise, that no leadership was taken by either PNF or CDB.
I would say CRM still worked because as we say: If you dont have any better idea, just keep quiet. PNF had some good ideas but he wasnt so sure because otherwise he would have insisted more or taken control of the aircraft (which he did from time to time, but without pressing the takeover P/B) So again, nobody really was in control because inputs add up or are neutralized.
Confusion was high but I am very sure CDB noticed the aircraft pitch attitude as he was walking into the cockpit because at that time (02:11:43) it varied between 10degrees up and even more and this is definitely different from what he experienced the other 100plus times when he entered the cockpit in normal flights. What he then saw when he entered the flight deck brought up the "c'est pas possible" because he (and nobody else of us) has never seen a combination of those readings before.
Old sentence but true:
In an emergency you will not rise to the occasion but fall back to your level of training. Were they trained for this situation?

@Neptunus Rex: ...inner ear pressure.
I would say if you are stressed like they were you dont feel anything

@takata: I have been trying to get info about VS indication on PFD(not data) and could not find any tests (AMM) were this system is checked. Maybe you have another source?

DJ77

6th Aug 2011, 07:08

There should be an increased effort to help pilots understand the very basic laws of physics involved, in very simple, and practical terms.

Are you kidding ?

BluJet

6th Aug 2011, 07:30

Hi peefactor,

Anyone have more experience with this ADR switching 'scrolling' aspect? good point, but on the A330, the "new information" (in this case ADR3) is presented much more instantaneously than on the "rolling" A320

A33Zab

6th Aug 2011, 09:33

What reason, what reason... would you like a +/- 10,000 ft treshold exceeded for inertial vertical speed? It is always the same reason, a designed parameter exceedance.

Thx, clear now.

The 'stable' inertial V/S was replaced by unreliable and fluctuating ADR V/S.

'Another slice and hole for the swiss cheese model'

henra

6th Aug 2011, 09:49

The inexperienced PF did try stick forward however a/c still stays nose up no response, as elevator is at -30 deg due to full THS! So behaviour is bizarre and only explained if you have a full understanding of the situation in 60 seconds.

Hmmm, where did you find this situation in the plots ????

Where was any indication the PF was trying to get the Nose down ??
In contrary the Nose descended a couple of times despite continued NU commands from the PF, albeit slightly reduced from full NU to half NU a couple of times.
In the last minute the PF even fought the ND commands of the PNF by himself applying Full NU.

Having a look at the traces I do not see anything there which would confirm your assertion that the PF was seriously trying to get the nose down.

JD-EE

6th Aug 2011, 10:52

takata posted the speed graph (http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-80.html#post6621344). It does not show something I expected. In climbing from 35000 to 37500 it should have lost just a whole lot more speed than the graph shows, which suggests the plane was in a rather significant updraft with most of its upward motion being provided by wind energy.

That ought to be food for thought here, too. It would likely be more conflicting or exaggerated data for the PF to digest.

Mr Optimistic

6th Aug 2011, 11:07

I though the 0.5*(v1^2-v2^2)=gh equation had been looked at earlier and found to be broadly consistent ?

In the more general discussion, has consideration been given to maximum altitude limitations if turbulent conditions are expected and unreliable airspeed remains a credible fault event which has to be accounted for?

The BEA report indicates that the AoA margin between stable cruise and warner was only 1.5 degrees. Given the coarse nature of the manual inputs it would seem that loss of autopilot precision is at best a serious matter at those altitudes and related/concurrent loss of air speed data and protections cuts one safety rope, then throw in turbulence.....In those conditions it seems that excursions towards a stall are likley even if one could hope that transition to full stall was avoided.

JD-EE

6th Aug 2011, 11:08

3holelover types, " I'm presuming those of you asking it are not pilots, because I can't imagine a pilot who could ever not know if he's stalled, PDQ, after the fact."

Then the PF on AF447 was not a pilot?

JD-EE

6th Aug 2011, 11:17

Neptunus Rex says, "The reaction on their inner ears should have told them that they were in a rapid descent."

No. Their inner ears can only tell them they accelerated downwards at some point. Once they are in a constant speed drop their inner ears would not sense the drop. They ears might detect something when pressure changed. Ears are tilt and acceleration sensors. They also have pressure on their backs to tell them the nose is pitched up - about the same as the instrument in front of their face tells them the same thing.

Neptunus Rex also says, "Plus, the Captain should have noticed the aircraft deck angle as he walked, or rather climbed, to the cockpit."

That one's a gimme.

Now, just how much of the acceleration into the fall they'd sense is up for grabs if the plane is in violent turbulence.

(Has learned far more about inner ears than she ever intended to learn due to a malfunction in my left ear similar to what the astronaut Alan Shepard had.)

Mr Optimistic

6th Aug 2011, 11:22

You seem to be up at an early hour JD-EE. At that rate of descent I would have thought the pressure change rate would have ears popping. then there would be the increase in temperature, however if all else failed there was always the altimeter.

JD-EE

6th Aug 2011, 11:30

Black Sheds, one might ask about what part of the plane being at fault for providing bad data in the period immediately after the aircraft went to ALT 2 mode. Airspeed was out. "Protections" were out. PF pulled stick up enough to cause a serious zoom climb that left the plane with an "apparent" airspeed of about 215kts. (Assumption here based on airspeed coming back briefly and the number reported being within reasonable bounds for the kinetic energy transferred into potential energy.)

What led the pilot to disregard stall warnings all the way down?

But most of all why did the pilot pull nose up on the plane right after (within a second or two) the AP and ATHR disengaged? He had accurate data up to that moment. And an average kid can extrapolate into the future.... The drill is "leave it alone, fly pitch and power until you have air speed back. Do not make any large sudden changes in either pitch (no nose up) or power (no TOGA)."

JD-EE

6th Aug 2011, 11:32

re airtren to lone - I think the word you're looking for to replace "lack" in "lack of lift" is "insufficient". As a matter of fact that is how I interpreted lone's comment.

By the way, what does the water bottle tell you that the pitch display does not? So far as I know that, at least, was still working.

JD-EE

6th Aug 2011, 11:39

funfly, you can be falling at mach 20 and not feel it. All you can feel in your ears or your body is a CHANGE in velocity. And there is no known body that, in air, continues to accelerate all the way down from 38000'.

Yeah, I'm picky that way. Please excuse.

jimjim1

6th Aug 2011, 11:42

JD-EE said:
takata posted the speed graph. ... should have lost just a whole lot more speed than the graph shows,

This graph does not show the velocity of the aircraft. It shows Corrected Air Speed (I think). True Air Speed would be a decent approximation for the velocity but CAS is not anywhere near at the altitudes involved here.

Can the meme that some hand of god is necessary to explain the zoom climb please go away. It has been demonstrated many times that there is about the right amount of energy available including an allowance for manuoevering losses.:ugh:

Ooh! Just been buzzed, well at 2,000ft, by the Dragon Rapide (from Duxford I believe). Way cool.

JD-EE

6th Aug 2011, 12:20

takata commented to A33Zab about the IR data.

Regardless of the IR data from ADIRU the ISIS data existed. And enough data was recorded that the BEA was able to follow altitude and attitude of the plane all the way down. What makes anybody think ISIS data was not presented in the cockpit?

If it wasn't ABI ought to be totally pilloried, if they did not make it available, or AF should be excoriated if they skipped over this as an "unnecessary frill option."

JD-EE

6th Aug 2011, 12:24

Mr Optimistic, "I though the 0.5*(v1^2-v2^2)=gh equation had been looked at earlier and found to be broadly consistent ?"

It was - with a speed at the apex of 215 kts, 240 kts maybe....

JD-EE

6th Aug 2011, 12:26

Mr O
Indeed - I am a night owl. And I thought I left room in there for cabin pressure sensing in the ears. But the inner ears don't feel even pretty extreme pressure changes unless you've had surgery that exposes the area by drilling through nice thick bone. All the inner ear senses is tilt and acceleration. And those can get mixed up very easily in a dark room.

JD-EE

6th Aug 2011, 12:31

I've said too much already but there is an observation I'd like to make.

Here is a simple sentence. "Our speed is 215 kts." This is in English. If I say it with flat or even feminine with the slight upward lilt at the end it means exactly what it says, the speed is in fact 215 kts. It's a statement of fact. If the pitch change at the end of that short sentence is made to sound like a question it is a combination question and statement of incredulity that the speed is 215 kts, "Our speed is 215 kts? (How in (censored) can that be?)" when the unstated part in parenthesis is included.

French adds handwaving to the picture. There's no way we're going to guess precisely what was said dissecting the words given us. And, as noted, even hearing the recordings won't necessarily help much.

Is there a better topic to be entertained about?

JD-EE

6th Aug 2011, 12:33

jimjim - accounted for - the energy loss work I did ran from the mach numbers translated back to speeds based on the speed of sound - an approximation. It appears to be about a factor of 2 give or take a bit for the correction.

CONF iture

6th Aug 2011, 12:44

FPV ECAMs fault are due to their selection and rejection (they were unselected before this point) because airspeed was < 60 kt.
There is no such thing as FPV ECAMs fault

But It looks to be set at +/- 10,000 ft in order to show a degraded status.
That's not supported by the traces as posted by A33Zab, something else but what ?

takata, you don't seem interested to address your notion of normality ...
There is a clear internal conflict in the selected vertical speed as there is also one in the selected Mach ... What is it all about ?

3holelover

6th Aug 2011, 13:02

Hi JD-EE,
Re: "Then the PF on AF447 was not a pilot?"

I think you missed the part where I said, "but since recent events have shown us such pilots do exist..."
Of course he was a pilot. Saying I can't imagine it isn't the same thing as saying it can't be.

I've said many times I think these poor folks were in a heck of an ugly situation. One might call it 'the perfect storm' to challenge his abilities... But he was a product of his training. Clearly, we're learning that many pilots don't know how their machine will behave when stalled. In my mind, that points to a serious deficiency in their training. I think it's akin to not knowing how the machine will behave with an engine out.

I suspect it's an inevitable result of the "cost effective risk management" biz... 'Creating a sim that can teach stall behaviour would cost too much and the aircraft are unlikely to stall anyway, so we won't bother.'

Which brings a question to mind... Somewhere I recall seeing a training aircraft (might have been a helicopter?) that had been designed with the ability to emulate the behaviour of multiple aircraft, depending how it was programmed.... Could such a system, in a small aircraft, be utilized to teach the stall behaviour of transport aircraft, I wonder?

ChristiaanJ

6th Aug 2011, 13:31

Which brings a question to mind... Somewhere I recall seeing a training aircraft (might have been a helicopter?) that had been designed with the ability to emulate the behaviour of multiple aircraft, depending how it was programmed.... Could such a system, in a small aircraft, be utilized to teach the stall behaviour of transport aircraft, I wonder?I recall seeing the same, although I no longer remember what the aircraft type was.

Howver.... the problem is the same as the sim: if you don't have accurate data for the behaviour of an aircraft well into the stall, there is no way you can program either your sim or your 'training aircraft'.

mojomoh

6th Aug 2011, 14:52

Not A helicopter - a converted C131 by Arvin Calspan.

Calspan Retires USAF's Last C-131 (http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogscript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3A27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3A7ba6b986-69f1-4053-99c2-8855a0fa5f4e)

Smilin_Ed

6th Aug 2011, 14:57

Dozy: Is that because you can't see any instance when it would be useful or because it goes against the methods you were taught flying aircraft with more "conventional" controls?

Autotrim is useful in ensuring that the aircraft remains trimmed when in autopilot so that when the autopilot is disconnected, either by the flight control system or by the pilot, he is not dumped into an out-of-trim situation. However, as I have said several times before, when I am hand-flying, I don’t want the system changing the trim. I want to do that myself. Trimming is not an arduous task. In fact, it is a completely natural act and it is second nature to a properly trained pilot. It would be even easier if the AB side sticks were equipped with “coolie hat” switches. That is my personal opinion as a pilot. You have told us that you are not a pilot so I believe that you have little basis for an opinion as to how you would want to fly an airplane. Apparently you are qualified to offer opinions on how software should be written to meet certain criteria specified by the users (the pilots), but it is those users who are best qualified to set the criteria in the first place. You have stated that there are good and sufficient reasons for the design of the software in the hand-flying mode, but AFAIK you have not offered any reasons why that design is preferable to my reasons for disconnecting autotrim when hand-flying. As a user, I believe that my preferences should take precedence over yours. I am open to reasoned arguments on that subject.

Dozy: IMO (for what that's worth) there's nothing wrong with the autotrim setup as long as the way it works is taught properly.

That’s your opinion as a non-pilot. It seems to be the consensus on this forum that the pilots of AF447 were not taught properly. It is my opinion, as a pilot, that because the autotrim continued to follow the inexplicable nose-up inputs by the PF, stall recovery would have been made more difficult, had they ever attempted stall recovery.

Dozy: If you look at the traces the trim moves minimally under automatic control. What caused it to deviate so strongly was a series of inputs that trended towards nose-up, the majority of which were around half the stick's rearward travel limit, that were sustained for the best part of 45 seconds. What caused it to continue the movement to the stops was a full nose-up deflection that lasted between a further 30-40 seconds - that's more than 1 minute and 20 seconds of nose-up input at a deflection that ranges from halfway to the stops - at cruise level!

I fully agree that the full nose-up trim situation was the direct result of the inexplicable nose-up inputs, but you need to understand the proper technique for hand-flying in turbulence, a technique which has stood the test of time over many decades. As I have previously posted, the technique for flying in turbulence is to first be properly trimmed before entering the turbulence and not to change the trim, allowing the aircraft’s designed positive longitudinal stability to keep you flying properly. That is essentially what the stated procedure is all about: “Fly pitch and power”. Presumably, AF447 was properly trimmed and the power properly set before the autopilot and autothrottle dropped out so they really didn’t need to do anything except take a deep breath and monitor what proper pitch and power was doing for them. If the dynamics of the weather take you off the desired altitude, you simply make small inputs to return to that altitude but you don’t change the trim because you want that proper trim setting to help you minimize excursions from the desired flight parameters. If, as a non-pilot, you think you have a better technique for flying in turbulence, please post that on the forum for the pilots here to consider.

Sometime back, someone here offered that the pilots of AF447 only needed to let go of the controls and the aircraft would have returned to normal flight on its own. While that is true with conventional flight control systems and a properly trimmed aircraft (for cruise), it was not true with AF447 because the autotrim had changed the pitch trim from a stable, level-flight setting. With a century of manned flight under our belts, the consensus of pilots is that aircraft should exhibit positive longitudinal stability. But the AirBus flight control system changes that, overrides the natural aerodynamic stability of the airframe and introduces neutral longitudinal stability when hand-flying. As a result, when a pilot moves the stick in pitch, the nose stays right there and will stay there even if the pilot lets go. It is my opinion as a pilot that an aircraft that exhibits neutral longitudinal stability is more difficult to fly properly than with positive longitudinal stability. If you have a different opinion, it will have to be as a non-pilot.

Dozy: The trim doesn't move in any noticeable way as long as the inputs are relevant to the flight regime. The PNF notices that the PF's lateral inputs seem to be extreme, and admonishes his counterpart. He then further upbraids the PF for commanding a climb when it is unnecessary. This is why the BEA recommend training for manual aircraft handling at altitude, because in this case the sidestick inputs are repeatedly way beyond what is reasonable at that altitude and airspeed.

It is my opinion that the pilots of AF447 were so poorly trained that they really didn’t know what had happened to the trim. For AB pilots, trim seems to be out of their notice in any situation except takeoff where they set it and forget it. Actually I believe that even if the AF447 pilots had known what had happened to the pitch trim, they would not have understood the consequences. They clearly didn’t understand much about flying an aircraft.

Dozy, it you have relevant arguments on why autotrim should not drop out with the autopilot, I will be glad to consider them.

There are other subjects which would be appropriate for separate threads such as the lack of tactile feedback in the side sticks, and whether or not it is appropriate to use the autopilot in heavy turbulence. I did not bring these up at this point because I wanted only to address your opposition to having the autotrim drop out when the autopilot drops out.

curvedsky

6th Aug 2011, 15:26

2011: Edwards AFB test pilot school has a variable stability F-16.

It is a one-of-a-kind VISTA (Variable stability In-flight Simulator Test Aircraft).

The VISTA can be configured to fly and behave like any aircraft, from a UAV to a C-17 Globemaster. It also has enhanced data recording capabilities.

Article at TPS's Test Management Program brings real-world projects to classroom (http://www.edwards.af.mil/news/story.asp?id=123249216)

deSitter

6th Aug 2011, 15:59

Well said, Smilin_Ed! Being a know-all is so endemic in the computer world that it's refreshing to hear the other side put the foot down.

ChristiaanJ

6th Aug 2011, 16:10

curvedsky,
Many thanks for that very interesting link.

And no, it was not an F-16 I was remembering, more like a large twin jet. Might have been a DC-9, a 737, or a large business jet.

Slightly O/T, but IIRC NASA has a few T-38s that can be reconfigured to "fly like a space shuttle" and that the shuttle pilots used to "stay current" and practise the approach.

Maybe they're for sale now?

jcjeant

6th Aug 2011, 16:27

Dozy: Is that because you can't see any instance when it would be useful or because it goes against the methods you were taught flying aircraft with more "conventional" controls? http://www.pprune.org/rumours-news/447730-af447-wreckage-found-134.html#post6623524
Know the aircraft you are flying ... it's help in some situations ....

Lyman

6th Aug 2011, 18:13

You are far too gracious. I won't belabor this, and won't stay, but this needs to be writtern.

Since the few days after the crash, a few PILOTS have noted the problem w/trim in Alternate Law.

Each time the THS moves, The airframe starts behaving like a different a/c. One reason I think the PILOT had problems with PITCH is at least because this ship did not want to lower her nose. Besides, when he did attempt it, He needed WAY MORE ND than he was comfortable with. WHY? because, as DOZY WANNABE has said... "The THS COMPENSATES for the elevator position". Go look up compensate, and think about if you would like to have a massive set of wings ON THE TAIL, "taking away" your elevators..... AUTOMATICALLY, and without any prompt on the Flight Deck.......

xcitation

6th Aug 2011, 18:18

Originally Posted by xcitation
The inexperienced PF did try stick forward however a/c still stays nose up no response, as elevator is at -30 deg due to full THS! So behaviour is bizarre and only explained if you have a full understanding of the situation in 60 seconds.

Hmmm, where did you find this situation in the plots ????
Where was any indication the PF was trying to get the Nose down ??
In contrary the Nose descended a couple of times despite continued NU commands from the PF, albeit slightly reduced from full NU to half NU a couple of times.
In the last minute the PF even fought the ND commands of the PNF by himself applying Full NU.
Having a look at the traces I do not see anything there which would confirm your assertion that the PF was seriously trying to get the nose down.

English BEA #3, Page 111, t>=02:11:00

Locate the 4 lines conveniently next to each other.
brick read, purple, cyan and green.

(brick-red line) look at PF nose downs (+ve above zero),
(purple) elevator max deflection down (forcing nose up)
(cyan) because the THS is auto trimming.
(green) the pitch stays nose up,

Example
t=02:12:17
stick 2/3 (10/16) forward deflection.
elevator -30 deg
THS -13 deg
pitch +4 deg.

My point is that the a/c sometimes did the opposite of inputs (pitch up with stick forward and pitch down with stick back). This was because a/c was dancing around edge of the stall from the outside of the flight envelope.
I stated this because someone said that you could just fly it by behaviour. The behaviour was terrible i.e. inconsistent and at times contrary to stick inputs. A/c needed to be flown by pitch and power with manual THS trim not by its behaviour.
Another point to make is that the instruments were impared, e.g. IAS, altitude etc. The true air speed and true altitude could have been different as noted by the QF72 incidents CPT.

DozyWannabe

6th Aug 2011, 19:05

Autotrim is useful in ensuring that the aircraft remains trimmed when in autopilot so that when the autopilot is disconnected, either by the flight control system or by the pilot, he is not dumped into an out-of-trim situation. However, as I have said several times before, when I am hand-flying, I don’t want the system changing the trim. I want to do that myself.

Fair enough, that's your opinion - but have you ever actually flown a FBW Airbus? Plenty that have state that the autotrim is completely unobtrusive when hand-flying and that the aircraft as a whole handles rather well.

You have stated that there are good and sufficient reasons for the design of the software in the hand-flying mode, but AFAIK you have not offered any reasons why that design is preferable to my reasons for disconnecting autotrim when hand-flying.

In fact I did, but it's several threads back - one of the reasons was the ability to have hands on throttle and stick in a pilot incapacitation scenario.

That’s your opinion as a non-pilot. It seems to be the consensus on this forum that the pilots of AF447 were not taught properly. It is my opinion, as a pilot, that because the autotrim continued to follow the inexplicable nose-up inputs by the PF, stall recovery would have been made more difficult, had they ever attempted stall recovery.

And it is my opinion that had the pilots been taught how to use the manual trim wheel then they would have had an option for correcting the position it ended up in due to the overcontrolling that occurred just after FMC disconnect. Of course, more fundamentally than that had they been taught how to handle the aircraft properly manually at cruise flight even that knowledge would have been a mere "nice to have".

And for the record, while I am a non-pilot and have never flown solo, I have been at the controls of gliders and trainers in my youth. I'm not just some techie trying to dictate the way you should fly, I'm just saying that there are valid reasons why the design is the way it is.

Sometime back, someone here offered that the pilots of AF447 only needed to let go of the controls and the aircraft would have returned to normal flight on its own. While that is true with conventional flight control systems and a properly trimmed aircraft (for cruise), it was not true with AF447 because the autotrim had changed the pitch trim from a stable, level-flight setting.

And had they let go of the controls then the elevator demands would have ceased and the trim would have returned to neutral. In addition, the trim wheel is available to move the THS back to a neutral position far quicker than the autotrim would have. There were plenty of ways to recover, but the overriding problem is that the crew failed to recognise the situation they were in and the reason they were in that situation (overcontrolling at altitude). The reason they overcontrolled was because their training was lacking, which is the fault of the airline and the industry.

Well said, Smilin_Ed! Being a know-all is so endemic in the computer world that it's refreshing to hear the other side put the foot down.

Not helpful -the only one showing a dismissive and arrogant attitude is you.

rudderrudderrat

6th Aug 2011, 19:54

Hi DozyWannabe,

And had they let go of the controls then the elevator demands would have ceased and the trim would have returned to neutral.
If only that were true.

Once the aircraft was climbing with fixed thrust, and with the stick pitch neutral, the FBW computers would maintain 1 g, and continue to trim the aircraft in pitch as the speed washed off.

In your glider, if you don't move the trim wheel, it will feel heavier in pitch the slower you fly - that feed back is missing with AB FBW.

When Normal Law is working it feels progressively heavy in pitch as speed reduces below alpha Protect, and impossibly heavy if you attempt to fly beyond alpha Max. ALT LAW has no such "protection" (Limits), nor any feel.

DozyWannabe

6th Aug 2011, 21:45

Once the aircraft was climbing with fixed thrust, and with the stick pitch neutral, the FBW computers would maintain 1 g, and continue to trim the aircraft in pitch as the speed washed off.

Could we get some confirmation from PJ2 or A33Zab?

(@RRR - I don't know about "belief" - I'm asking for some confirmation. Either way it doesn't alter the fact that without overcontrolling, the THS wouldn't have ended up in that position, or that it was possible to set the THS position either by maintaining nose-down inputs or moving the trim wheel. RWA seems to be under the misconception that autotrim commands a THS angle and holds it there regardless of input, when in fact it's just following elevator demand - a mistake I made when I first started looking into this)

rudderrudderrat

6th Aug 2011, 21:47

Hi DW,

You can't believe it either can you?

xcitation

6th Aug 2011, 22:23

It appears that rudderrat is correct.
If only Normal law had been preserved.

ALT law took out the following protections:

pitch attitude
low energy
alpha floor
high speed
turbulence damping
Low speed stability protection becomes active. Near stall this brings up a black and red barber pole (oblique stripes?) on the PFD speed. However a black and red ladder (horizontal stripes) is the overspeed!!!
This is surely a trap for mis-interpretation. Why on earth do they use the same colors for overspeed ladder as stall ladder in ALT law! Remember in Normal Law the stall ladder is amber.

Anyone else confirm this?

LOW SPEED STABILITY PROTECTION
An automatic nose down command is introduced to increase speed. No reference to AOA, only speed. Operates 5 to 10 kts above stall warning depending on weight & slat/flap configuration. The pilot can override.
"STALL" announces and crickets heard prior to stall speed being reached. PFD shows black and red barber’s pole for stall warning speed. V-apha-prot and V-alpha-max are replaced by Vsw (stall warning speed). No alpha-floor protection is available.

mm43

6th Aug 2011, 23:31

Ex BEA - Interim Report No.3 - page 76 ...

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

The French version of this statement on page 78 is more verbose, but has arguably led to a misrepresentation when subject to translation. However the French version is the work of reference, and I've changed the NU inputs to ND inputs in my English copy.

MountainWest

6th Aug 2011, 23:52

Smiling Ed and Rudderrudderrat – you are patient and well spoken. I like your style.

I am a pilot, though just VFR, and wouldn’t presume to compare my piloting skills with yours or most of the contributors on this site. I do, however, know a thing or two about IT and implementing automated systems. I am not anti-Airbus, anti-Boeing, or anti-anything else. I am pro-arrival-at-my-destination. IT has taught me that thoroughly tested software can – and does – go wrong, and that just because something can be automated doesn’t mean it should be. Critical systems should, IMO, allow human beings to interrupt the automation when appropriate; i.e., “Give me the speed even if it is below your threshold!” or “Give me the AoA even if it is unreliable!” Perhaps that would have helped on AF447.
My hope is that the authorities will consider how decisions made years ago led to some of the confusion in the cockpit. There apparently was a mindset years ago – later reconsidered - that stall was no longer an issue. Did that misplaced confidence in automation pervade the builders and operators? What (if any) other design features are based on the assumption that automation will prevent bad situations? Several people have commented on design and training issues in which pilots lost to IT or bean counters (or perhaps other pilots). These include the stick issues including simulated feel, the lack of AoA indicator, visibility of pilot actions, etc. Dissecting how the old decisions were made, and whether they were good or bad, would be a good lesson in organizational dynamics. I also wonder:

1. What led to the decision to disable SW and displays below certain angles and speed thresholds? Several have said the AoA vanes work fine down to a light breeze. Were 30 deg and 60 knots (IIRC) chosen as limits because out-of-range values are unreliable or because the software would “protect” them from that situation?

2. Why no audible auto-trim? That seems quite an oversight to this novice. A lot of training emphasis was placed on avoiding manual trim. Did the designers think trim – like stall – was a non-issue? Maybe someone felt an audio feedback would just encourage pilots to be more aware of trim, and that was presumably a bad thing. The software, after all, would make that a non-issue.

3. What led to all the laws? The mixed-mode operations and varied levels of degradation seem confusing and counter-intuitive. I read it in the comfort of my chair with tequila at hand. How would it feel to be handed this situation at altitude, mid-Atlantic, 200 souls on board, improperly trained, for the first time?

IMO, too much false confidence in a number of areas led to the disaster. Designers were confident of “protections” that didn’t cover all the bases. AB failed to appreciate the significance of the pitot failures and the risk of simultaneous loss. AF was unable/unwilling/unaware re training issues. The gentlemen flying the aircraft were handed a basket of snakes. I’m not qualified to say anything about their actions, and hope never to be handed a situation like that.
Pardonne-moi pour le poste de longue.

takata

7th Aug 2011, 01:44

Hi Blujet,
Welcome back, sir.

@takata: I have been trying to get info about VS indication on PFD(not data) and could not find any tests (AMM) were this system is checked. Maybe you have another source?
Did you check 34-14-00?
In fact, the Vertical Speed displayed is either "baro-inertial" (not only inertial) or "barometric". My first guess, from graph, was that no inertial V/S data was displayed passed -10,000 ft/mn. But it is not correct. The word range is +/- 32,768 ft for baro-inertial v/s, and only +/-20,000 ft for barometric V/S.

So, in fact, the reason should be simply because all ADRs were rejected by they respective IRs (this 0211 FLR ACARS discussed previously). It will become NCD and replaced by ADR source V/S on PFDs.

- Inertial vertical speed (365) and inertial altitude (361) computation:
The IR software contains a baro-inertial loop to compute the Inertial Vertical Speed and Inertial Altitude. This loop permits to take advantage of the different qualities of the inertial and air data systems. The IR brings its better behaviour in dynamic maneuvers while the ADR brings its stability in time (no drift of the outputs like in IR).

The ADR source to be used is selected according to the configuration of the discretes described previously. When no ADR source is available, Inertial Altitude and Inertial Vertical Speed are sent with their status matrix coded NCD (No Computed Data).

The principle of the baro-inertial loop is given here:
http://takata1940.free.fr/baro_inertial_vs.jpg

deSitter

7th Aug 2011, 03:57

Not helpful -the only one showing a dismissive and arrogant attitude is you.

Arrogance is to assume that anyone who really flies worries about V_office-chair.

bubbers44

7th Aug 2011, 04:27

ALT law took out the following protections:
pitch attitude
low energy
alpha floor
high speed
turbulence damping

I'm curious why the pilot pulled up with no overspeed warning. Since the CVR had no such warning why did he pull up? Inexperience or trapped pitot presure with his climb causing static pressure to indicate an overspeed with no warning.

xcitation

7th Aug 2011, 04:50

I'm curious why the pilot pulled up with no overspeed warning. Since the CVR had no such warning why did he pull up? Inexperience or trapped pitot presure with his climb causing static pressure to indicate an overspeed with no warning.

The initial pull up immediately after AP disconnect IMHO was because pitch was 0 deg, altitude descending. For some reason his 2/3 deflection pull up maintained a level altitude for a number of seconds (downdraft?).

Subsequent pull ups IMHO were because he saw the red and black barber stripes (low speed stability protections for stall only showing in ALT/DIR LAW) on his speed and mis-interpreted as the red and back horizontal striped ladder of overspeed. The actual speed showing as being low - but he understood speed had failed. In normal law the low speed bar is amber.

Happy if someone can debunk/support my speculations.

Old Engineer

7th Aug 2011, 05:15

Just a number to many people. It is in takata's post a bit above, #1698. But it has a special significance in computer programming. It is half of a "64K" space, sometimes called a page space. In the simple program "Notepad" it was the maximum number of characters in any note you wished to jot down, for example (at an earlier time). Usually adequate for that, but if not, too bad.

Here it is the number of possible ft/min, up or down, that can be displayed, for vertical speed. I don't want to argue here whether it is an adequate number, but simply to point out the way in which the binary computer efficiency considerations can influence the range of "instrument" displays.

The numbers in this 64K space require 15 binary bits (ie 0 or 1) to represent them, plus a 16th to represent the sign. Computer words are commonly multiples of 8 bits in length these days.

Actually, in one version of implementation of this numbering, 32767 positive values are available, 32767 negative values, and two zero values. That's right, there are two zero values in the most simple arrangement-- plus zero, and minus zero. That wouldn't be so bad if level flight didn't require a zero value. I'm not being facetious here-- this one issue alone required a lot of attention in many computer applications over the years.

The point here is that there are many things in control by computer program that are subtly different from the way we are trained to think, and may occasionally lead to unanticipated results in service. This is going to be particularly true in computers pushed to the maximum in speed with a minimum of size, weight, and power consumption; using software written by people in organizations under similar pressures, to some extent.

The views of pilots as to how such software is working in practice therefore deserve some respect. Unfortunately, once the aircraft is sold, the rewriting of software doesn't contribute anything to the making of that sale.

takata

7th Aug 2011, 05:58

The initial pull up immediately after AP disconnect IMHO was because pitch was 0 deg, altitude descending. For some reason his 2/3 deflection pull up maintained a level altitude for a number of seconds (downdraft?).
Illusion, deceleration, and weather.
- Illusion because altitude recorded is "indicated", then partially false at UAS point.
- Deceleration, because autothrust started to reduce N1 by 16% seven seconds before UAS event.
- Weather because there was an up/down/up.

Subsequent pull ups IMHO were because he saw the red and black barber stripes (low speed stability protections for stall only showing in ALT/DIR LAW) on his speed and mis-interpreted as the red and back horizontal striped ladder of overspeed. The actual speed showing as being low - but he understood speed had failed. In normal law the low speed bar is amber.
Happy if someone can debunk/support my speculations
Easy, there is no low/high speed stability in Alternate Law 2b, No red and black striped "barber/ladder".
I already mentioned that many times: SPEED LIMIT FLAG ON PFDs (both).
Neither did the speed "fail" at this point; they "failed" (NCD) when sensed under 30 kt during the stall sequence, much later.

CONF iture

7th Aug 2011, 06:55

The French version of this statement on page 78 is more verbose, but has arguably led to a misrepresentation when subject to translation. However the French version is the work of reference, and I've changed the NU inputs to ND inputs in my English copy.
You're absolutely correct.

rudderrudderrat

7th Aug 2011, 07:34

Hi DozyWannabe,
Either way it doesn't alter the fact that without over controlling, the THS wouldn't have ended up in that position,
I disagree.
According to the description given in FCOM the aircraft will attempt to maintain pitch and 1g. Even stick free, whilst climbing and decelerating - it will trim more nose up. At the apogee, as it started to fall, provided the sensed g was greater than g/2, then it would trim even more nose up in an attempt to hold 1g.

Perhaps you wouldn't find any of that confusing because it behaved as it was designed, but with a lifetime of conventional aircraft handling qualities behind me - I would most definitely find it confusing.

Normally, when the automatics don't do as we want - we take manual control (as a simple starting base) and then add the automatics gradually.
This crew never had a simple manual control starting base.

alainthailande

7th Aug 2011, 08:13

Originally posted by Old Engineer
Actually, in one version of implementation of this numbering, 32767 positive values are available, 32767 negative values, and two zero values. That's right, there are two zero values in the most simple arrangement-- plus zero, and minus zero.

Been a systems engineer for almost 30 years now, and I've never heard of a signed 16-bit implementation different from the traditional -32768 to 32767 that has exactly one representation for zero (what you call "minus zero" actually being -32768). Any reference to this particular implementation you're mentioning?

Old engineer as well.

CONF iture

7th Aug 2011, 08:23

So, in fact, the reason should be simply because all ADRs were rejected by they respective IRs (this 0211 FLR ACARS discussed previously). It will become NCD and replaced by ADR source V/S on PFDs.
On a speed base, the IRs decide to reject the ADRs, but still prefer to be replaced by them on a V/S base ... it is getting complex again ...

The IR brings its better behaviour in dynamic maneuvers while the ADR brings its stability in time (no drift of the outputs like in IR).
Now, how to qualify the AF447 event ... ?

Anyway, thanks for your research takata, that's interesting documentation.

JD-EE

7th Aug 2011, 10:24

3holelover - indeed it was a perfect storm. It was as if the events were tailored to send that specific pilot to the briny deep.

My imagination stretches farther than yours, I guess. I remember me when I got out of college. I surprised many of my new peers with my understanding of electronics. I still needed some pointers. Then I learned why I surprised them. I saw some other raw graduates who'd never fallen in love with their chosen profession and learned, avidly, everything they could. They knew the bare minimum to hold their grades. They were good. But, faced with something outside their specific schooling left them in shock until somebody older poked them the right way. (I think I alienated a lot of fellows when I'd tinker in the corner and finish the project they were working on while I was also tinkering with the project I had at hand. Thankfully nobody ever asked me to build something into neat little boxes. We had some very good lab technicians for that, thank God! I'm not quite helpless when faced with tools and scratch building. (sigh))

He was schooled. He knew what he was doing. But the precise sequence of events threw his schooling right out the window and, it seems, "I want UP" screamed through his system as logic left.

JD-EE

7th Aug 2011, 10:40

Smilin Ed, out of curiosity what is the rate of change for the THR in manual control mode? How fast can it move 13 degrees? If 0.65 degrees per second is as good as it gets does that adjust your distaste for the auto-trim in any way, especially if that magic number and the actual time it takes to go from neutral to stop in both directions are taught very clearly in training?

If 0.65degrees/second is as fast as it gets and the pilots know this instinctively them holding the elevator is a one control option for controlling the elevator and spinning the trim wheel. You get the same effect.

I've been wondering if there is some place on that panel to put a cartoon of the plane that shows the control surface positions as reported by the feedback position sensors. It could be ignored until a pilot wonders if something is wrong or stuck. (Or perhaps if the PF was mucking it up.)

And, please, I am just asking. Knowing is better than guessing, not that I expect to ever be writing such software. Maybe somebody else who will be designing such software will read it and consider it fully.

JD-EE

7th Aug 2011, 11:11

alainthailande (http://www.pprune.org/members/216241-alainthailande), as an engineer practicing for even more years than that I have heard of the double zero implementation. Most of the old vacuum tube er empty state electronics computers used it. Sign magnitude is not particularly uncommon until the last 30 years or so. (Gawd - 1980 is THAT long ago! Maybe more like 40 years?)

(Honest, I still have some black hairs..... I'm not all the way white! Suddenly, though, I feel staggeringly old! Um, and when I was a kid the age I am now was considered to be quite old, too.)

Linktrained

7th Aug 2011, 12:02

Old Engineer #1701 wrote:
" Once the aircraft is sold rewriting of software doesn't contribute anything to the making of that sale." True enough, if that is the only sale that you as a Salesman hope to make with that Purchaser...
The Marketing Department would wish from more sales from a satisfied and profitable Customer.
I have mentioned earlier that one manufacturer, B., sent me an overnight Telex on how to load their, our, aircraft. Another manufacturer, also called B. whose aircraft we operated, could not, or did not wish to do so... and did not...
Guess which manufacturer was successful in further orders...

DJ77

7th Aug 2011, 12:17

Guess which manufacturer was successful in further orders...

Was not it B. ?

3holelover

7th Aug 2011, 12:26

:E Give that man a prize!

JD-EE

7th Aug 2011, 12:55

Linktrained, marketing isn't the only powerhouse that can lead to changes like new software. Legal can also be most persuasive when they remark casually that not fixing these here bugs will cost the company billions....

But it's a REALLY hard sell for an engineer to get something changed on aftermarket equipment unless she can engage Legal.

Smilin_Ed

7th Aug 2011, 13:13

The gentlemen flying the aircraft were handed a basket of snakes.

Not really. All they needed to do was to:
1. Take a deep breath and watch what the aircraft did under the pitch and power that was set before the AP dropped out.
2. Make gentle corrections to ensure that altitude and heading were maintained within some reasonable limits given the turbulence encountered.

Instead, they panicked, pulled back on the stick, and, with the help of autotrim, pulled the airplane up into a stall.

Smilin_Ed

7th Aug 2011, 13:15

Smilin Ed, out of curiosity what is the rate of change for the THR in manual control mode? How fast can it move 13 degrees?

I'm the wrong person to ask about that. Someone who is familiar with the actual implementation of the flight control system should answer that. Dozy?

rudderrudderrat

7th Aug 2011, 13:26

out of curiosity what is the rate of change for the THR (THS?) in manual control mode?
There isn't a figure published but it's very easy to move it at say 10 times the auto trim rate.
The biggest advantage is that I now know where it is and if and when I moved it.

Mimpe

7th Aug 2011, 13:27

If thats true Ed, then any stall recovery proceedure for an Airbus must include immediate check of Trim status. Otherwise the gadget designed to save has also been inadvertently designed to quietly kill.

The sufficiency of the autotrim's response to any emergency pitch down commands would have to be immediate and adequate, otherwise the system "as a system " couldnt be safe /recoverable in an attitude upset.

Linktrained

7th Aug 2011, 13:41

It WAS... Wait for it... B !

Engineers can wave reports like BEA's in front of their favourite bean counters and ask how much has been budgeted for any Legal costs should we be mentioned, even in passing. Our Publicity Department may have ideas for "correcting" publicity requirements for years ahead. Ticket Sales... etc.

Safety is no Accident

Jig Peter

7th Aug 2011, 14:04

Until quite late in the descent (if I remember an early post) the cabin was normally pressurised (8-9000 feet ?), so in spite of the climbing and descending (or most of the latter) there would be little or no chage in the pressure on the pilots' eardrums, until the pressurisation controller announced that it was unable to keep up with the rate of descent.
Until that moment, the crew would probably do their own version of the "Valsalva manoeuvre" - i.e just "click" their eardrums without doing the full "hold nose and click" business. At least that's what I remember doing almost automatically in the 1950s designed military aircraft I was privileged to operate, and those aircraft were pressurised to a much lower degree than passenger-carrying aircrtaft, so your eardrums acquired a fair degree of flexibility.

In any case, with all the other things their eyes and brains had to contend with, eardrums would be, to say the least, Low Priority.

Config Full

7th Aug 2011, 14:32

@ A33Zab

I have a question on AOA data. The FDR records their actual values, which we get in the report. But wasn't these values fed to the ADRs, which in turn were rejected? Where did the PRIMs get the data from and how did they elect the data as correct to trigger a stall warning? (Shouldn't AOA be correlated -at least to a certain degree of incidence- with airspeed, which was unreliable?)

DJ77

7th Aug 2011, 15:19

Hi Smilin Ed,

I generally share your views about autotrim but we have to acknowledge that many pilots love it and find the bus safe, easy and pleasant to fly.

When I was teaching pilots converting from Airbus to the 777, they had to adjust during the first sim sessions about having to trim and a few lesser handling problems. To those who complained I said from now on they would have to earn their living honestly :). Whilst I am sure manual trim is right with a classical control column and wheel, I cannot say it’s the same with a sidestick controller a la Airbus.

Choosing “C*” law implied autotrim: you cannot rely only on elevator to compensate for speed, configuration, or thrust changes while maintaining a constant path stick free. Besides, streamlining THS and elevator improves aerodynamic performance. The 777 uses a “C*-u” law in normal mode and does silently autotrim when compensating for configuration or thrust changes but you have to “trim to speed” to compensate for speed changes. In another design, Gums had to trim the Viper to “gee”. None of these designs preclude implementation of powerful protections at both ends of the flight envelope.

For Airbus, longitudinal static stability (LSS) is restored by software in normal law when approaching the limits. I believe this was one of the Special Conditions of certification and was called “proof of concept” at the time. The problem which I think was disregarded is the lack of LSS in ALT2 law. Imagine the THS could not move further up as soon as the stall warning activates: most probably, even with consistent full back stick, the AoA would not increase enough to the point where the stall alarm is silenced.

It is Dozy Wannabe’s opinion that the THS rightfully moved to 13 deg up in AF447 because it’s what the PF requested. It is apparently not Dozy’s opinion however that the THS should continue to trim up in normal law when high AoA protection is active and the pilot pulls on the stick, since the software prevents it. Where is the logic?

DozyWannabe

7th Aug 2011, 15:28

I'm the wrong person to ask about that. Someone who is familiar with the actual implementation of the flight control system should answer that. Dozy?

I don't have any numbers, but the question is not so much the speed of actuation (which would be the same), but the speed with which that actuation is demanded. You can crank the manual trim wheel round to neutral in a couple of seconds, and the actuators will catch up, but to do it via autotrim will take sustained nose-down inputs over several seconds, which appears to be something that many pilots aren't comfortable with doing.

Autotrim is designed to take the load off normal control inputs, not recover from extreme THS angles. I think to correct the THS angle with autotrim in time to effect a positive recovery would have required recognition of the situation and corrective action at a considerably higher altitude than with manual trim operation.

ChristiaanJ

7th Aug 2011, 15:32

I've been wondering if there is some place on that panel to put a cartoon of the plane that shows the control surface positions as reported by the feedback position sensors. It could be ignored until a pilot wonders if something is wrong or stuck.Concorde of course had that, even though it wasn't a 'cartoon', but a separate electro-mechanical instrument (the "Icovol"). It showed the position of all eight control surfaces, and the control mode for each (blue or green electric signalling - aka FBW - or mechanical).
And yes, Concorde also had an AoA indicator.....

3holelover

7th Aug 2011, 15:39

Airbus will also display that on the ECAM FLT CTL page. (but you all knew that, right?... Is the suggestion for a separate screen always displaying this?

gums

7th Aug 2011, 15:43

Hats off the Rudderrat for pointing out one of the unusual characterisctics of the FBW concepts that emphasize Gee versus AoA for pitch laws.

The stability that Smilin'Ed describes can be implemented quite easily in the FBW systems, and the plane tries to achieve the TRIMMED AoA versus the TRIMMED gee if you relax pressure on the stick. The system can also make the "move" aggressive or rather wimpy.

Both the 'bus and the Viper engineers went with the "trim to gee" approach, which has some problems, as the Rat describes. The 'bus actually compensates for pitch in Normal Law by adjusting the trimmed gee when not in level flight (not so the Viper, as it goes to whatever trimmed gee the pilot sets - minus 2 or so, up to plus 3.5 gees) . So with the 'bus in a turn of 30 deg back we get a trimmed gee of about 1.1gee for neutral stick. Kinda neat. In a climb of 30 degrees, we would get a trimmed gee of 0.87 or so. but here's the biggie.....

If the system loses the pitch/roll correction, then it looks like it seeks one gee. So RudderRat's observation is very germane. You can wind up with a plane trying to increase pitch even with a neutral stick input. In fact, it's an aspect of the Viper logic that "helped" us achieve the deep stall none thot possible. If you zoom at sufficient pitch, you can "fly" past the "protections" on inertia and have a plane incapable of introducing a useful nose down pitch moment, especially if the c.g. is far enough aft.

My personal opinion is most pilots would prefer the "trim to AoA" approach. The plane would closely resemble, if exactly "feel" and act like older planes. It would "unload" the gee if you were holding back pressure commanding an AoA above the trimmed AoA, and exploit the "natural" aero characteristics of the plane - really great statically stable or less stable as with the Viper.

I guess the engineers decided that the "gee" command approach could be implemented more reliably/easier using internal sensors of the FBW system itself. But even so, the Viper used the AoA probes for limiting our AoA, and it worked very well.

PuraVidaTransport

7th Aug 2011, 15:47

Let's face the facts that led to this tragic accident:

1) A captain, knowing that in the next hour the plane would be in a more dangerous portion of the flight, ITZ transit, decided to take a rest break. He suggested the PF take the break, but changed his mind when pilot flying says he isn't tired. Then, instead of giving command to the fresh (and more experienced) pilot, he gave it to the 'baby pilot'...even having to ask if he had the correct license to be the Pilot-in-Command! Still find it interesting the first BEA report says he didn't have the right license but the third does...sure that was just a clerical error. :confused: POOR COMMAND DECISION

2) When the autopilot/autothrust kicked off, the plane had a nose-down (or at best level) attitude with reduced engine thrust because of the compensation the autopilot was making in that moment for turbulence. Pitch was not correct, power was not correct so doing nothing would not have been acceptable. The pilot needed to make two immediate corrections, one to correct the roll and the other to correct the slight nose down (or flat) attitude. If he followed standard pitch/power memory items where he would have leveled the wings, put 4-5 degrees of NU and added the bit of power the autos reduced seconds before, he would have been fine. His continued nose-up inputs, even as he is saying he is going back down, shows a very poor understanding and control over the primary flight control, the side-stick. POOR TRAINING

3) Problem came with over-control in BOTH axis. His over-corrections were noticed (in both axis) by the PNF. The PF did not correct the situation and being 'commander' refused to release control to the PNF who seemed to have a better grip on the situation. POOR TRAINING

4) Just before the (real) stall, the airplane was fully recoverable with proper procedures. Again, despite the stall warning and advice from PNF, the training of the PF was not up to the task of simple stall recovery i.e. GET THE NOSE DOWN. Of course, he might have reverted to his 'Normal Law' stall training, holding stick back to get max performance. Too bad he was in 'Alt2 Law' which doesn't give those protections/help. POOR TRAINING

5) After that point, the pilots/aircraft are into the 'Test Pilot' regime. NO ONE could have known the performance of the aircraft in this flight envelope because no one is stupid enough to put this aircraft into that position to get that data. The whole point to training and hiring competent pilots is so they NEVER get into this situation to start and if they do, have been trained with basic flying skills and upset recovery to have a chance to save the plane/passengers and their own lives. NONE of the three pilots on the flight deck at this time had a clue what to do. VERY POOR TRAINING/HIRING/PROMOTING

My take on this accident is the pilots, especially the PF, gave us one of the worst "FAILS" in aviation history. The plane can be blamed for the initial problem, but many crews have walked away from identical incidents. In this case, very poor training on flying at altitude, no teamwork between the two pilots, clueless about the true nature of the emergency etc... If it were me, I'd put 10% on Airbus for the pitots and the way the stall alarm functioned. The other 90% has to go on the pilots which really means Air France and their training/hiring/promotions...

After reading the entire three reports, no way you are getting me on an Air France flight be it an Airbus or Boeing craft... I can accept one pilot messing up under high stress, but for ALL THREE to remain so clueless indicates a BIG problem within Air France IMHO.

Lyman

7th Aug 2011, 15:50

question for Mimpe?

Can you expand on that "quietly kill"? The way I see "Trim"'s function is a smoothing of flight in longer time frames than when needing to Manoeuverr? In other words, say a Pilot is in a situation that requires "maneuvering" more than cruising, wouldn't the Trim work against him?

As in, favoring his inputs NOSE up? Damping his nose down elevators? With a large trim nose up, his Pitch responses would be out of his comfortable rate and trend experiences? And also be variable as the THS was in transit? just a thought

Wouldn't Trim be far down his list of "controls"? in an emergency.? Why would he want any additional inputs at the tail other than his own, even if he was aware they were happening.?

The simple fact that the Trimming Horizontal Stabiliser is manually controlled by a central wheel that requires total focus and many repetitive (read, time consuming) and large hand excursions seems to be an awkward step especially in a confusing and emergent setting?

ALTERNATE LAW: "STAB TRIM" NOSE UP 7

OR TRIM : UP 7 or 6, or 10, or 13

OR TRIM :DOWN 3

Again, would a pilot even want turtle trim in his quiver in UPSET RECOVERY?

DozyWannabe

7th Aug 2011, 15:58

It is Dozy Wannabe’s opinion that the THS rightfully moved to 13 deg up in AF447 because it’s what the PF requested. It is apparently not Dozy’s opinion however that the THS should continue to trim up in normal law when high AoA protection is active and the pilot pulls on the stick, since the software prevents it. Where is the logic?

The main difference is that in Normal Law, all the inputs to the FCU and FMC can be trusted - therefore it is likely that the computers will know more about the plethora of aircraft parameters at any given time than the pilots, who are relying on an instrument scan and therefore only a subset of available data at any given time.

Alternate 2 is only triggered when one or more of the flight surface, sensory or computation systems have failed. At that point the system is designed to acknowledge that the computers' ability to assess the situation is impaired, and give complete control to the pilot. This presumes that the pilot knows his aircraft and how to handle it (which makes the assumption that Airbus designed their aircraft systems around the idea that pilots are largely numpties not only wrong, but pretty ironic in hindsight).

In essence, when you get ADR DISAGREE and Alt 2 clicks in, the computers are saying to the pilot "I can't trust these readings and I don't have your problem-solving skills. You can not only see the instruments but can also see outside. I'll help you keep the shiny side up based on what I know, but if I'm wrong you can override me". Unfortunately in this case the pilot made control inputs way in excess of what was appropriate, overrode the "soft protections" in doing so and stalled the aircraft, apparently because he was not appropriately trained.

rudderrudderrat

7th Aug 2011, 16:18

Hi DozyWannabe,

You made an interesting observation about pilot instrument scan and I agree with you:
…it is likely that the computers will know more about the plethora of aircraft parameters at any given time than the pilots, who are relying on an instrument scan and therefore only a subset of available data at any given time.
but I disagree about the help the automatics will give:
In essence, when you get ADR DISAGREE and Alt 2 clicks in, the computers are saying to the pilot "I can't trust these readings and I don't have your problem-solving skills. You can not only see the instruments but can also see outside. I'll help you keep the shiny side up based on what I know, but if I'm wrong you can override me".

So the pilot only has a subset of available data with UAS, he does not have the benefit Longitudinal speed stability in ALT2 Law, he has to keep it shiny side up himself with Roll Direct (which he appears to have found "very twitchy"), and the auto trim is silently trimming the load from the up elevator well beyond alpha max.
What a magnificent design!

DozyWannabe

7th Aug 2011, 16:24

So the pilot only has a subset of available data with UAS

He has pitch and power, which should be all that is necessary.

he does not have the benefit Longitudinal speed stability in ALT2 Law

I'm still not sure about the argument there - the flipside is that in the case of a small-intermediate upset he has complete control of elevators and trim in one hand and can manage throttle in the other.

he has to keep it shiny side up himself with Roll Direct (which he appears to have found "very twitchy"), and the auto trim is silently trimming the load from the up elevator well beyond alpha max.

Twitchy my foot. Control at altitude is about very small, corrective movements until you get a feel for how the aircraft is responding (even this "know-all", "office-chair" non-pilot knows that much - and no, that is not directed at you... :)) - he was mashing the stick halfway to the stops from the get-go, so much so that the PNF repeatedly chastised him for it.

ChristiaanJ

7th Aug 2011, 16:32

Airbus will also display that on the ECAM FLT CTL page. (but you all knew that, right?)... Is the suggestion for a separate screen always displaying this?
I don't know what JD-EE intended.
The 'Icovol' was hardly a primary flight instrument, but then of course Concorde may have been FBW, but it was not a glass cockpit, so a space for it was found on the central panel.

I've refrained from commenting on the autotrim issue, because the only autotrim I know was the Concorde one.... and that was a separate computer, and an electro-mechanical actuator, that moved the neutral point (in pitch) of the stick. And autotrim also moved the manual trim wheel, with the obvious 'ping', 'ping' of the bicycle bell.

As an ancient, I'm still somewhat astonished about the lack of "feedback" from the aircraft to the pilot, which seems to have disappeared slowly....

No 'stick force', other than a side-stick spring (crikey, even MS Flight Simulator and other games now come with force-feedback joysticks).

Concorde had FBW, so no direct force feedback from rods and cables either, but it had a quite sophisticated 'artificial feel' system and I've never heard complaints about it.

No 'throttle position feedback' - on Concorde the autothrottle computer controlled an autothrottle actuator, which moved ... yes, the throttle levers themselves.

No 'bicycle bell' on the pitch trim.

Concorde of course had André Turcat..... who stuck his nose into everything, including a lot of aspects of the "pilot-aircraft interface".
For those of you who read French, read his book "Essais et Batailles" (sadly it's never been translated).

I tend to think the FBW family (A320, etc.) never had the benefit of 'ancient' pilots like him.... but I may be wrong.