NASA had an orbital configuration display software one would often see during slow spots in Shuttle mission coverage. One glance at this screen and the configuration of the craft relative to the Earth was instantly obvious. In the open areas of the display one found all the necessary data to have a precise description of the Shuttle's configuration.

Why cannot a modern aircraft have such a display for itself?

Not one proposition offered to mitigate the THS fatal flaw here was NOT looked at by Airbus.

One thinks one can solve a problem that one assumes to have been OVERLOOKED? By AIRBUS?

3hl : perhaps the solution to a "go to your room" command to THS in other than NORMAL LAW is not necessary afterall.

Airbus, in their wisdom created AL2 with ROLL DIRECT. PITCH NOT DIRECT.

They still wanted the a/c to have some "say so"

The pilots can be trusted with ailerons and spoilers, but not the TAIL.

Initially, when the THS did NOT contribute to the zoom climb, it looks like a good idea.

Let the elevators nudge the a/c into a crazy climb with the Computers help? YES. The climb is a pattern of UP nibbles and retreats, in thrall to the PF's STICK. With each nudge to a higher AoA, the computer forgot the last one, and the zoom climb resulted. Then at the top, it forgets its last nonsense, and tries to maintain a load.

Going up, maintain load, at the top maintain load. The PF is not the only one who appears to have lost his "mind".

So the THS was not "Jammed"? Baloney. Two powerful motors were holding it against the Top curb. It was free to move only upon command, a command of NOSE DOWN. It recieved plenty of these, but the computer disallowed them v/v THS.

Pilot responsibility? Of course. AIRBUS? You make the call.

If elevators can (and should be) used to recover, or maneuver, or maintain, etc. Whose idea was it to throw in a silent partner?

Flying is NOT inherently Dangerous, that is a bromide, and demonstrable for those of us who hang on to the hero pilot meme.

It is inherently SAFE, as the statistics PROVE.

jcjeant,

If I read again your previous post, I think it is quite a bit about semantics.

It is easy to agree with your saying that the "pitot tube was not faulty", as I take that as the "pitot tubes were not defective", as the pitot tubes functioned normally in different conditions than those when they failed.

But even if they were not faulty, they did fail, as a device can fail, without being defective, when in an abnormal operation conditions.

But, IMO, you're raising a high threshold for yourself in saying: "The pitot tube operated normally .. as required by its specifications and certifications". The "required" implies IMO that the language in the specs/certifications is strong, some wording that is equivalent to the combination /MUST/MUST NOT/, i.e., mandate the freezing in the conditions of their failure, and mandate the providing of inaccurate information in the condition of their failure.

Are you sure about meeting that threshold? ...

From post #101:

@USMCProbe:

There's one small problem with this. At 16 degrees pitch attitude and AOA in excess of 35 degrees, do you know where the "bird" is on the PFD?

(Any 'stall prevent' use of the "bird" would have required monitoring and honoring FPV ("bird") thru the "ballistic" portion of the "zoom", the caveat of course, it must be selected and available.)

edit: BTW there are a lot of pilots trained to use FPV.

Hi,

The language used in certification .. the words used must be accurate and not misleading and should not allow an interpretation that could afford not to keep strictly to these specifications
If this is not the case these certifications are useless and therefore the classification societies and certifications societies (and regulators) must be submitted to an external audit to detect problems .. skills or organizational
Trials and penalties can be at the corner .. as those specifications concern not only technical matters but also human lifes.

As a clarification, I think, like you, I expect the specs/certs to be non-ambiguous in defining the operational conditions, and functions within those conditions.

Without the specs/certs in front of me, I don't know if that non-ambiguous language extends to the range of conditions which is outside the operational conditions, as that's outside the scope. Therefore, I asked my question, as the possible ambiguity for the outside operational conditions range creates the difficulty of meeting the threshold, which I think you've set for yourself, with the wording you've used.

Ok, enough of this THS speculation.. I (and others) mooted extreme concerns over this (misuse case) style of behaviour hundreds of posts ago... a few others didn't agree, or thought we were grasping at straws - fair enough.

Hopefully, and looking at BEA wording, it will not be ignored and pushed to one side - everything is relevant, even irrevelances (in that they are tagged irrelevant!)

Now, we can look a bit further away... ?

I can certainly see that calls for some 'neutering or neutralising' THS logic in 'apparent' stall situations raises eyebrows, mine as well.

What goes right back to basic aircraft certification requirements in the 60's, is the stick-pusher. Indeed, RudderRudderRat just suggsted a stick shaker mode would be somethingt that makes some sense

So far, AFAIK, certification requirements mandated combined shaker and stick pushers for only those aircraft with deep (e.g. potentially irrecoverable) characteristics.

I would think AoA measurement has become easily reliable enough for this to become a safe option for all airliners above a certain size... the prelimary vibration itself could quite possibly have been enough to shake PF out of what may have tunnel vision.
THS activity and detected position would automatically have to be become part of stick shaker activity.

Airtren.. damn good summing up above :D

If we intend to hold somebody accountable to fix something than semantics is damn important lest they end up saying "it ain't my job" Improving the Pitot tube or avoiding weather entirely (because we can't readily see the stuff) will not prevent the next accident when this system fails in a different way (flocking birds, volcanic ash or ice sheds from in front of the pitots or even a loss of vision or whatever powers the instruments that displays the speed) That is what I mean by a system failure.

The system failed ....l so what? To fix the problem we need to examine not just this one specific failure condition but to revisit the assumptions in the basic certification (which assumes this system would fail) and address every one of the assumptions that was violated.l

I have no respect for the assignment of cause "but-for the icing of the pitot" that is typical of the legal tort system when it comes to adressing flight safety shortfalls in complex system interactions.

IMO this problem is not going away with just the final accident report summary or all the rhetoric of PPRune "I told you so" until wide ranging recommendations are adopted..

Certification (s)

Of course certification must keep up with increasing experience, whether for speed or pitch information.

Under the Regulations of sixty years ago any aircraft ( A330 ?) would be restricted to flights not exceeding 1000 nm over water or 1500nm overland. Longer flights required the carriage and use of a Flight Navigator, who would need a sextant and a means of checking the compass (Astrocompass ?) and a Drift sight. (Please don't suggest an astrodome on a pressurised aircraft - I think that someone lost their Navigator through one, then !)

There was a list published of some 30 odd UAS incidents which had not had MAJOR problems. Someone ought to know why. (NWA had ice crystals and were 25 miles away from a Cb.)

Historically many/ most aircraft accidents seem to have come from the convergence of several (often three) factors, each relatively minor or individually surmountable. Each factor, when indentified or even suspected ought to be remedied, so that THAT factor does not happen again.

If you are pilot, you better know what you are getting into. Nobody is building any airplanes that flies by itself. If you as a pilot do not comprehend the meaning and the peril of what a stall is and it's dreadful implication and possible fatal consequence, you have no business being in a cockpit and even less being in charge.
I am no pilot but even I know that when flying the main objective is not to FALL as in hitting Mother Earth FALL. By the time Altitude became meaningful again in that AF447 cockpit, it was too late.

THS did what it was supposed to do. If the PF wouldn't have applied NU for more than 3/4 of the 4 minutes (give or take)of the incident opening and closing the THS would have never moved at all.
ND would have probably brought the THS down if application of the SS would have lasted long enough.

The pitots have already been dealt with by the industry which incidentally just acted in flight AF447 as a casual instigators of life eternal pop test quizzes.

A captain knowing that bad weather was approaching ahead, decided it was a good time to leave the cabin. Say what?

The PNF (First Officer and probably future candidate for Captain) heard at 02 h 10 min 10,4 : SV : “Stall, stall” (without cricket). And he said: What is that? EXCUSE ME? "You ain't a passenger Mr.! You should and ought to know what STALL, STALL means preferably waaaaaaaaaaaaaaaaaayyyy before that tragic night. On top, later he can be heard desperately calling for the captain to come back to the cockpit. Don't know, but I think he was supposed to have acted as replacement captain not a captain caller. A pilot might need schooling to learn how to recover from a Stall of any kind but he/she does not need a whole schooling to learn that a Stall might get you kill along with all your passengers. That's my take.

And then there is the young PF. What can we say that can bring some meaning, reason or just some measurement of mitigation? That he was young, maybe? Not even.

A flaw was finally found and subsequently corrected in the Comet. But no R-E-D-E-S-I-N-G was ever made except for the upgrade to the Comet 4. They serve their time proud and tall afterwards. There are almost 1,000 A330 already made and in service. Any major redesign will be just done on newer future versions of Wide Body Twin Engine Models.

Retired, I believe we did discuss this a couple of threads ago, and the concensus was that in Alt Law

If you use the trim wheels to move the THS, it will over ride the auto trim. Once moved, and then left alone, in Alt Law auto trim will again move it in response to the usual inputs.

Is this trained in the Sim?

Again, the point was raised in re some Unusual Attitude training scenarios, which isn't the same as an Airspeed Unreliable scenario.

I think we are in violent agreement, more or less. :cool:

A casual observation. If some 'blend' of manual/auto commands (THS) are mandated, do we have an alert then, in/out? Prolly not. "Who's on first?"

In a DIRECT LAW situation, only manual. So in between, and true to "gradual" and "graceful" degradation, a fuzzy mush of "What are WE doing now?" The Waltz, or the Lambada?

With the brain lock some see here, is that at all fair?

Just because it's too much for me to imagine, I'm sure it's just the thing.

More prompts, more recorded music, more Synthetic verbalie. Soon, a Choir, then a symphony?

When run out of ideas, make it merely more complex? There is a gaping hole in there between Cruise and recovery from UAS. Those who downplay it should be chastened by now? Perhaps not, given the onset of the academy awards for those sold on the platform without reservation.

VGCM66
 

Please,

if you are new to this thread and want to contribute something useful out of your expierience as an engineer or any other profession you are familiar with, it would be appropriate to read the nearly 1.000 pages filled about this flight.
That would tune you in the loop of the discussion.

There had been failures, there had been mistakes, and there are things which can be improved to reduce the probability of similar accidents.
The big question to all these matters is "why"?

Your ranting does not contribute to this task.

There's no such certification requirement as it would be impractical to design aeroplane this way - please refer to DP Davies' masterpiece, page 35 onwards. Also it is entirely possible to certify passenger transport aeroplane that once stalled, cannot be unstalled by anything except improbable amount of luck, produce it in hundreds and have fly around for decades in statistically acceptable safety. It's not A330, if you wonder. Again, DP Davies' work is painfully relevant. Surprisingly to some, not me.

To meet certification requirements of stability and maneuverability at diferent speeds, altitudes, weights, configurations and CG positions.

With all three ADIRUs losing speed signal, aeroplane is so confused as to know nothing. Mind you, I 've used "confused" and "know" figuratively. No computer installed on A330 is intelligent therefore it really doesn't know anything and it cannot be possibly puzzled. It works within limits of its instruction code.

THS went up to trim aeroplane into AoA it could not possibly sustain. Triggering condition was sidestick pitch command.

There's good chance that even if there were trim in motion aural warning, it would be overridden by stall warning. OTOH, simple mechanical device like bicycle bell would be heard all the time during normal ops and probably wouldn't be noticed after a couple hundred of hours in flightdeck.

They can't. DP Davies explains why, page 35 and on.

There were at least six cases of total airspeed indication loss due high altitude icing before 447 on AF 330/340 fleet alone and allegedly there were about 30 cases worldwide. That every affected flight, bar one, continued and ended safely somewhat contradicts the notion of systemic failure.

Big chunk of my flying is done through clouds made of ice crystals and I have never had my pitots frozen. Not every ice crystal will stick to your probes or compressors and ideas when and where can we encounter the dangerous type are currently extremely vague. If we were to avoid every CB plume in the sky, soon we'd measure our deviations in hundreds of miles and schedules would become a joke.

You are not mistaken. Not a little bit.

Utter lie, no, not even a lie, it is pure BS. Flying is fantastically dangerous. Statistics is hard science and can't prove inherent safety of anything at all. What your numerology that you have the cheek to call statistics fails to appreciate is how everyone in aviation needs to work his or her butt off to make potentially very lethal activity into something that the ignorant considers safe based solely on outcomes.

If only sheer ugliness of twisted bits of metal that used to be an aeroplane, now littering the seafloor or some mountainside, breaks up your dream of flight being safe because it's not dangerous in first place, don't come to PPRuNe for lullaby to put you back to sleep.

bear
One of the reasons in getting a type rating, and qualified on a given aircraft model, is to study it, fly it and by so doing learn how it works, and what makes it work well enough to safely operate it.

Each aircraft will have some different characteristics than others. The art of design continually evolves, so it should not surprise us.

What most professional pilots do is, rather than grouse about whether a particular combination of features pleases or doesn't, is learn how it works and how to make it fly well.

The objective of a professional training program is to make the above happen.

VGCM66
 

RetiredF4

Just like Orville and Wilbur, many of us have started as Newbys at some stage. Some of us may have learned ( and understood ) everything in a single presentation. Others may be helped by a further explanation or example, even when the initial version may prove to have been in need of even wiser thoughts, often from people like yourself.

There were 3 trained pilots in this a/c. Although you can argue that the man machine interface had its failings (stall warner behaviour, lack of explicit AoA, failure to scream the THS was at the limit of its authority), the concern about pilotless aircraft is that human beings are adaptable and flexible and cannot be programmed out. This accident makes you wonder about the value of human beings versus machines: did they deliver their value here ?

Sounds good, lonewolf.

#1 It didn't work.

#2 I have the distinct impression some qualifieds here are not in synch with the A330, or with your anlaysis, which I personally find impeccable.

#3 The difficulty with this Discussion is its free flow, and that is fine.

My opinions are based on my experience, and knowledge. As such, they mean probably nothing to anyone else. So what. Tell me, as a helicopter pilot, your impressions of having a combination manual/auto Trim on your aircraft. In Alternate Law, a regime virtually unflown in these circumstances by most if not all of the pilots currently operating the A300xx. On a moment's notice. No Sim, No Button. No ReDo.

It is so easy to focus on one thing, and that, as a pilot, can be deadly, hence your excellent posts on SA.

You scold the pilot group with innuendo that "Learn the Airplane"? is what's missing, the platform shows no unscrutables?

Or was it meant for me? Either way, it is not productive, and unlike your proven and excellent understanding.

Thousands of people have DIED to make flying Safe. It IS safe. Inherently Dangerous sounds like a line from a B movie. Driving is more dangerous, statistically, and in personal experience. Not all who fly are dumb.

I watched once at a test flight prior Launch. It was a wicked new and complex machine. The Pilot was confident, no, arrogant. fifteen minutes later he was burned beyond recognition, along with his a/c.

That isn't danger, that is insanity. The bottom line is the argument at all, here. Entrenched on the one side, over confident and arrogant on the other. A finding of any kind is pounced on, and morphed into "evidence." For what? EGO, and PRIDE. To my way of thinking, in furtherance of making flying LESS SAFE.

Personalyzing the debate is irritating. There is great stuff here along with the dross. Me Dross? Obviously, according to some, even most. Perhaps in my own eyes.

Mark my words, Aviation is careering into the weeds in front of us, and absent some patient direction from a source heretofore unknown, it will succeed in its quest for BBR.

autotrim under stall warning
 

How stall warning didn't supercede that condition ... ?
Curious to see if the BEA will be curious about it ...

Hi,

Clandestino:
So certainly with the insight of the AF447 accident you must think that the pilots were in very bad luck for have the 3 Pitot tubes frozen dead ..

And also with the insight of AF447 accident .. you must think that if they avoided the CB plume by hundred miles .. the schedule was a joke .. but the passenggers and crew will be alive today .. commenting about their delay at arrival .....

That question should be and will be forwarded to human factors experts.

If you'd like to suggest that stall warning should automatically stop the trim dead, it's a bad idea. If THS helped one get near or into the stall, last thing he needs is frozen trim - it must help one out of the edge of envelope too. I simply can not mention name of David Pettit Davies - a superb pilot, brilliant writer and overall a great man - enough times in this thread.

You have correctly interpreted part of my post. We know that "bad" ice that sticks to heated metal parts of the aeroplane, like TAT probes, pitots and engine compressors can be found in turbulent area near CBs but chances of finding it in aforedescribed areas are one to unknown, unknown being estimated as quite high. We only have anecdotal evidence that one type of probes is more often affected by "bad ice crystals" than other. We don't know why they get blocked but we're replacing them to avoid further incidents, which is quite reasonable and does not imply that probes are faulty. They just cannot cope with conditions met only very rarely in flight and there is no chance of replicating them in test conditions.


That's a severe misinterpretation, sir. Flying is extremely hazardous enterprise and while appearance of thunderstorm clouds near desired route brings hazard level one notch up, overall risk increase is only slight. Sure, those CBs in ITCZ will certainly kill you if you fly into them but only those ignorant of way aviation works will make a drama out of it. There are hundreds of flights daily through ITCZ , there are thousands of deviations around CB every day and every now and then loss of airspeed indications ends up as brief note in airline safety bulletin, passengers being largely ignorant that their flight was anything but ordinary. So we as pilots do everything right most of the time.

Icing of the pitots was freak incident. Crew's reactions were unbelievable. Investigation moves into HF field.

There's excellent editorial in jul-aug issue of Aviation Safety World. Everyone, do yourselves a favour and read it.

And yet autotrim (up into a stall) is still catching out boeing pilots too. The bus (outside of direct/boeing law) will at least wind the trim back down if ask for nose down. Wheras it seems the 737 at least will wind the trim up to the stall warning and then leave the pilot to remember (or not...) to unwind it in recovery. Which is "better" ??

The trim would have moved straight back down had they requested nose down beyond what the elevators could deliver. They didn't. They needed what 30deg(?) nose down to recover - never asked fro anything close. There was no stall recovery attempt that was stopped by the trim, there was no stall recovery attempted - period.

Had the trim movement kicked the crew in the rear or slapped them in the face for every degree it would have made no damn difference - they would have said yes trim me up, I'm trying to climb and the elevators aren't working... Had the THS ignored them and (say) gone to neutral, they would have overidden it with elevator all the way down. Had they had spotted it ignoring them, they would probably have manually trimmed back up (and what should the poor plane do then?). Why? Because they wanted to climb.

They were pitched up 15deg, falling out of the sky, plane not responding to controls [also low airspeed but they aren't sure on that]... and they had no clue they were stalled. Never mentioned. No (verbal) response to the stall warning - except perhaps "I’m in TOGA eh" [so I can't be stalled?] Throttles forward, stick hard back, why aren't we climbing ? "But we’ve got the engines what’s happening"

Sure, make the trim wheel clack, and in this case it's going to do all it's clacking during that 1min continuous stall warning. They didn't hear that, why would they hear the trim clack ?

I think you lumping all the crew together... a few of us here (maybe a lot) are pretty sure that PNF was heads down while some of this was going on and not aware of long term NU inputs, or position of THS. Clacking may well have garnered his attention to NU trim and thus validity of SW... so yes, I anyway, disagree with you.

But as RRR suggested, a stick shaker and even subsequently a pusher may have been the only way with that crew on that night, in that aircraft

On Stall, Stall recovery and THS automation.
 

Clandestino,

I've read your recent posts with interest. I appreciate your sharing your experience and opinions.

Regarding the Stall, Stall Warning and THS, here are a number of clarifications:

As the operational recovery procedure from a Stall has been already revisited post AF 447 accident, there is a growing sentiment that it is time, for a closer look based on AF 447 data, and prior data as well, also to the automation being involved prior and during Stall, involving such elements as THS - the AF 447 case is bringing additional elements to those existing from previous incidents, documented by BEA reports.

BEA reports of incidents involving Airbus Stalls show that often the Stall Warning was active in parallel with the Autotrim moving the THS in max NU position, so the AF 447 case is not unique.

In some of the few Stalls that were followed by successful recovery, the BEA reports show that pilots struggled aggressively and valiantly with the combination Autotrimmed THS at max NU + Elevators max ND, which was a considerable obstacle to defeat.

On reflecting, it seems that in a Stall, a THS max NU, if anything, is only diminishing or delaying the effect of the Elevators ND, at a time, when the effectiveness of the Elevator ND is crucial and has stringent time constraints.

A successful Stall recovery involves a transition from Stall/NU, to ND with Elevators ND to regain speed, with loss of altitude, followed by Elevators NU, to level, and than regain altitude. It seems that in such conditions, having the THS stable in an Optimal Position from a Stall Recovery perspective - the Neutral position - which makes Elevator NU, or ND more deterministic, is a much better choice than having it move slowly from one position to another, under automation control, at times when the effects of Elevator ND, and/or NU have to be maximum and immediate, and are under very stringent time interval constraints.

It is more and more clear (to me) that the THS has a slow, longer time range stabilization function, which does not fit well with the short duration and requirements of quick transitions from NU/Stall, to ND and than NU during the Stall recovery, therefore, it is much better to have it neutral during these transitions.

Lastly, the suggestion that seems to have circulated during the past several pages regarding the THS at Stall is that it should be brought automatically to the Optimal Position for Stall recovery - Neutral Position - as opposed to being stopped in its current position, whatever that may be - which seems to be your understanding of the suggestion.

Hi Infrequent,
So you are planning to tape over any trim-in-motion bicycle bells that they stick in your Airbus cockpit because you don't want to have a clue?

The AF447 PF may have been completely clueless, but if either the PNF or Captain had tumbled to the trim position, do you really think they would have persisted in ignoring the possibility of stall? You have to give people a chance to get the information they need, even if their attention is distracted elsewhere. Stealth change in the position of a major control surface is downright hazardous.

Safetypee recently posted some interesting links. One of these is an excellent paper by Donald A. Norman titled, "THE PROBLEM OF AUTOMATION" http://www.jnd.org/dn.mss/Norman-overautomation.pdf
One of the paragraph titles sums up a key element of the problem: "THE PROBLEM IS NOT AUTOMATION, IT IS LACK OF FEEDBACK."

Do you remember the FBW pilot's favorite question? "Whats it doing now?"
That is the issue. The Airbus does not speak or gesture very effectively. How can flight crews maintain understanding of what their aircraft is up to? How do we keep the crew in the loop?

I can see no reasonable means of engineering a system which would "reposition" the THS as a result of being in a detected "stall".

The whole point of being in a degraded mode with reduced or no envelope protection is that the system can no longer rely on one of its primary protection inputs - alpha.

if, despite that lack of reliability in alpha the system were, in a degraded mode, to have authority to move the most power single surface on the aircraft through close to full authority ( NU to neutral is a LONG way) it would be utterly impossible to show the system as being safe - in the event of an erroneous AOA input, you'd still be exposed to a large stab runaway, in effect.

With the AOA reliability suspect, the system can no longer act, automatically, on AOA. All it can do is draw the attention of the crew to the apparent high AOA situation - shake, shake - and hope they, with their human reasoning and airmanship, can resolve the situation which is outside the design parameters of the FBW system.

Unfortunately, in this case, they couldn't or didn't.

MadScientist

Surely alpha AoA is NOT suspect in Alt2 degraded mode. In fact AoA is (or should be) one of the easiest and most reliable of all transducers and can easily be kept independent.. that's why I find that a fully dynamically balanced vane was black-balled below 60 kts... It should never be black-balled... it should be extremely lightly spring loaded to a nominal 0 or 2,3 degrees +ve - for a low speed oscillating case, an RMS value could be used, and finally disregarded if mean and peak vales exceed a given ratio... for airspeed to be in any way involevd in its output IMHO is wrong.

There are also fairly easy ways to measure AoA less accurately as a fall-back value, electronically using hot-wire anemometry, as well as other methods

So, bear with me. Say the Bus had gone to DIRECT LAW. There was a contingent not that long ago pushing that position.

TRIM is out of the picture, (Only manual, and they didn't notice it in AL)
A Stall surely, and a recovery with or without the PF's stick. He picked up the Roll pretty quickly, would he have grokked the situation in DIRECT? Would he have held Back ss through the 14 or so phugae? Or would he have recovered. Probably a dumb question. Except... in DIRECT, TRIM is optional. This STALL entry was unconventional... they never felt the joy of the nose dropping like a rock.

The Bus flies pretty well in the Stall......

MFS, (agreeing with HM # 145), in this instance the AoA input might have been affected by a suspect ADIRU; there is no evidence of that, but there is valid supposition that the crew disbelieved the AoA derived stall warning.
However, the irony is that the requirements for an independent highly reliable stall system warning implies that AoA would be available for both stall warning and THS reposition – even an auto stall recovery (akin to a super stick push). The mechanism might be similar to existing Mach trim functions in the flight control computer.

MadScientist,

With the AF 447 BEA Report at hand:

Based on the BEA graphs, in the AF 447 case, the start of the Autotrim THS move towards max NU coincides (pretty much) with the start of the constant/continuous 53 seconds Stall Warning. During that period, from the beginning and close to its end - perhaps for about 40 seconds, the graphs also show NON-oscilatting (i.e. stable) AOAs emitted by IRSi(i=1,2,3) (page 111).

In this case, the system didn't really have to move the THS, it only had to stop the Autotrim from moving it from its -3 degrees position.

Back to the suggestion, perhaps there is a misunderstanding.

The suggestion in essence was not intended as to provide more automation during a Stall, but rather slightly change it, by reducing or eliminating the automation of the THS, in association with placing the THS in the "most optimal" position for the Stall Recovery. What the latter means, in terms of "optimal position" can certainly be the subject of more studying, but as a start can be considered THS Neutral.

Lastly, resolving the stability of the Stall Warning may provide the additional stability for the THS mechanism.

Lyman;
I am not sure how ACARS would report the FPV not working. I suppose it is possible. The Bird is not a "thing", it is calculated from the IRUs, and represents the course, both vertically and
horizontally, that the aircraft is moving. It is completely unrelated to any pitot static system, and does not rely on AOA measurements either. There are 3 IRU's on a 320 (maybe one more on a 330?). Any one of them could calculate the FPV.

The ACARS could report that the IRU's were not working, which would mean the FPV is not working, but I don't remember that from the data that I have read. It was only pitot-static information that was bad, for a short time, during the accident. At least that is what I have read thus far.

I flew 3 different jet aircraft with AOA as the primary performance instrument. The last one also had a HUD with the FPV. The great thing about the FPV on a PFD is that it gives you instantaneous information, including AOA, irrespective of what is going on with the pitot static instruments, and does not require any additional "scan" . It is where you are looking most of the time anyway.

Hi USMCProbe,

Most of the time - it is turned off because the SOP is to use FDs. If you turn the FDs off, you then have to press another button to turn the PFV on.
If you are stalled, (with AoA in excess of 45 degs) it will be out of view (off scale below the visible part of the the PFD).

Apart from that - it's very simple to use.

Exactly my point. If it is more than 8-10 degrees down from the pitch bars, your AOA is too high. Push forward until it is 2-7 degrees and keep it there. If it is "PFD-limited" i.e. off scale at the bottom, you are most definitely stalled.

And yes most of the time the "bird" is off , but they had over 3 minutes to hit the button and call it up. They were not trained to do this, and it would have probably saved the plane if they had been.

I would like to hear more about the ACARS report saying that the FPV was not working. Does anybody have any info on this? I can't believe a software generated symbol would be "monitored" and reported. The IRU's yes, almost for sure.

Hi

I agree with the first of your ideas (reduce or eliminate the automation of the THS) but not with the second part (repositionning the THS to neutral when stall warning is ON), as I feel unconfortable with this last idea.

Why not "simply" prevent any further NU movement of the THS by the auto-trim while the stall warning is ON ? This way :
- you prevent the automation to make the situation harder/longer to solve (THS full up = reduced ND effectivness = bad when stalled)
- but you don't inhibit/freeze totally the auto-trim (if you apply enough ND stick, the THS will eventually move ND too)
- you don't prevent the crew to manually apply (trim wheel) more NU or ND trim depending on their assessment of the situation
- you don't add another alarm (USE MAN PITCH TRIM type) to an already stressed crew to process.

Am I missing something? :)
I'm not sure that it will have changed anything substential in AF447's case, but I thought it was worth thinking about it.

On a side note, re the clues the crew had about the THS position : There was the trim wheel index, but also the F/CTL page on the center screen (showing all the control surfaces state, including numerical value for the THS angle). That page was automatically called due to some of the failures AF447 encountered (see ACARS analysis in interim reports #1 & #2).
It was not enough for the crew to notice. Sensory overload I guess?
I then support the idea of a clicking trim wheel, as it may give "another chance" to notice.

From BEA's interim report #2, ACARS analysis:
@ 2h11, for the first time, as CAS lower than 60kt was measured.

Hi AZR,

Thanks for the reference.

So despite being airborne (no weight on wheels, RAD Alts > 0 etc.) AB designed a system which removed both the stall warning and the FPV when IAS<60 kts.
What a wonderful system.

Communications is the solution. (Actually, it solves an incredible lot of problems most people don't think of.)

When the auto-throttle and auto-pilot disconnect and Otto says meatware has the plane PF should start to execute the correct (UAS) drill AND PNF should start reading out the procedure to be checked off one by one. The PNF should call it out loud and clear. PF should repeat loud and clear.

If they face a memory drill, PF may act, but PNF must call out the memory procedure and PF must acknowledge with the full step's instructions. Then you have two human brains working on the same problem in case one flies South for the winter or something. If PF fails to acknowledge PNF swats him over the head with two day old pizzas. If PNF fails to call out the drill, PF shouts obscenities about his 33rd cousin's maiden aunt - anything to get the communications cycle running with check and cross check.

It's so darned simple it's not even patentable.

I tell you three times, Communicate, Communicate, Communicate. Therefore it must be true. (Sorry Mr. Carroll for mangling it. But, as a dirty job it had to be done.)

Hi JD-EE,

I agree when conducted in a calm, relaxed atmosphere. Verbal communications on top of the plethora of cockpit noises, causes some noises to be filtered out. (Stall Stall??).

The big advantage of connected control wheels, is Pilot A Knows what Pilot B is attempting to do without a word being spoken.
AB have designed a flight deck where the crew are separated by their control sticks. They may as well be in separate rooms talking to each other on the telephone whilst watching their individual Flight Displays.

Lone, if the plane has been showing a ground speed of say 475 kts and an airspeed of 275 kts. The airspeed goes away because somebody insulted the pitot probes. If the ground speed drops but stays above 200 kts should the plane decide it doesn't know AIR speed so it should not impolitely sneer at the pilot about the plane stalling? Seriously, simple loss of airspeed is not a total loss of the ability to make a usable guess of airspeed for at least a few minutes with regards to stall warnings in a sane world.

Unfortunately, in the case at hand, I really don't think that would have made a difference. PF lost his head through lacunae in his training, unrecognized fatigue, or some other factor we can only guess about. PNF was not being communicative enough calling out proper procedure so that the cockpit TEAM were working on the same problem with their full brains. (And don't forget that two day old pizza for waking up the PF.)

A33Zab quoted: The altitude indications are based on GPS data. Two amber dashes cover the last two digits because the GPS altitude is less accurate than the barometric altitude.

I can (sort of) understand that back when the Denial Of Accuracy or dithering or whatever you want to call it was enabled by default on GPS. 100 meters was about as good as it got. Now it's about 10 times better between the DOA going away (I had a paw or two in that design) and basic improvements in clock and ephemeris accuracy. I wonder if TPTB have recognized this and given GPS a slightly better reputation and treatment.

Of course, I am presuming they have the intertial platform providing aiding data to the GPS receiver to help it track through extreme turbulence and other high dynamics conditions.