Hi PJ2, thanks for the refresher - yes, I remember the VSI needle clearly during the AF447/UAS exercise. Unfortunately I don't remember checking an analogue standby altimeter (I don't know if there was one), because I was so dead-set on committing what the PFD was showing me to memory.

I also remember the altimeter digits themselves changing to amber, but going back over my notes that may have been during a different exercise (the TRE very kindly let me have a go at a couple of landings in the time remaining) - it's possible an MDA had been set.

Hi PJ2,

Just a thought. Even though the PNF announced the ALT law change about 16 secs after the commencement of the event, the PF didn't acknowledge the law change 'verbally'. Perhaps he was doing just what he had learned about manual flying in Normal Law - pull back a bit on the SS and the aircraft would look after itself. Possibly the same reason could be responsible for him not acknowledging the Stall Warning.

On the other-hand the A/THR had also dropped out, so was he even 'thinking'.

But when it comes to the niceties of PFD color changes, and what the VSI does when you go 'off scale', this was beyond the PF's experience and training. In that respect, I suggest that neither the PNF or the CAPT recognized those significant changes - except I suspect the 'penny had dropped' when the last comment on the CVR was made.

Hi mm43;

It's my general impression that the circumstances faced by the two First Officers went rapidly beyond their experience and their training. I think this was partly due to the absence of a disciplined response to the event and to the ECAM. The PNF tried to "re-group", but such a response, when not initiated by the PF, is difficult to initiate or re-focus once the PF has already taken an independent course of action. The obvious solution was to take over and lock the PF's stick out of the loop but "the obvious" as it now appears to us gets into hindsight work which always has the solution!

In Canada, the CARS do not require that the stall be demonstrated on fbw aircraft once the initial PPC has been done on a type new to the candidate. In practical terms I believe this lack is being generally ignored and these events are actually being trained in recurrent work.

The one puzzle for me and for which it is impossible to determine a definitive answer is, why take a transport aircraft to a pitch attitude of 10 degrees at cruise altitude, at any time? Such pitch attitudes have an inevitable outcome in terms of rapid energy loss and as such are deeply ingrained and counter to experience in flying these aircraft.

A one-degree pitch change is dramatic enough, and so large changes are just never, ever done in normal flight conditions where the airplane was and remained stable, which this was. The assumption is that everyone knows this "through experience and their imagination" but perhaps that is not always the case especially where there is little to no opportunity to hand-fly these aircraft and / or it is never taught.

Many answers have been posited as to why the pitch-up...PF responding to loss of altitude (indicated...about 350'), or initiating the memory item of pitching the airplane up in response to the loss of speed indication (as per the UAS memorized drill), turbulence and inexperience in manual flying thus little appreciation of the massive inputs that small stick movements have, somatogravic illusions...There are numerous explanations which we, with full knowledge, may posit but can never know.

Hi,

PJ2
I think the answer will be found at the trial
Your Honor .. after deliberation we have a verdict:
Incompetence

Speed ...
http://i.imgur.com/GyPs35b.jpg
Alternate law
Also like you have overspeed ?

I don't think so - it's right here (Page PFD5 - top of the table - "PFD Altitude Indications" and PFD6 "Vertical Speed") :

http://www.airbusdriver.net/EFIS6.pdf

jcjeant, probably me but I have no idea what you're talking about, sorry.

TNX, Doze for the pages to show the displays.

For some reason, I wonder about the same "yellow" bars whether you're too fast, too slow, too whatever. Seems to me that slow or too steep or too high of an AoA or poor power setting should be red if low and green if at the desired condition ( up to a point) and then yellow or something to show above or below desired whatever. Then red is way outta line. In other words, keep everything green and you're as good as all the computers think you should be. And an arrow to show where you should be putting in controls. Of course, judgement and experience should take charge interpreting all the colors and raw data and colors, ya think?

'Bird and others here have flown the "indexer" doofers for AoA on approach, and they showed arrows to get to the desired value, and they were of a different color. Even we dumb fighter pilots could understand.

The early 70's lites had HUD displays that showed flight path ( FPM) WRT horizon and actual Earth. Trust me, a comfortable feeling coming off a CAT shot on a moonless night on the ocean. Ask any Navy Sluf or Hornet or Tomcat pilot.

In the AF447 accident, an inertial FPM would have shown the precise trajectory of the jet WRT the local level regardless of the air data. So no big deal. Keep the velocity vector on the horizon and then troubleshoot the air data problem.

Some jets had features to help "lead" course and vertical steering to the desired course, approach angle, whatever. We always looked at the raw data to ensure that Otto wasn't driving us into the mountain or the ocean.

I realize that installing and certifying a HUD for the commercial planes would be expensive. But I am here to tell you that it was one of the neatest things to have in low-vis approaches and when the air data went tits up due to iceing or otherwise. Always had the ADI for basic attitude and roll, but that FPM on the horizon line was of great comfort.

I am afraid that all the colors and such were of little value to those FO's on AF447, and some basic flying skills were also absent. CRM is another problem, as most here seem to agree.

In case of over speed do you see the same SPD word on blue background ? like as you see in alternate law after AP and auto THR disconnected (AF447) ?

@DozyWannabe,

Thanks for the PFD link.

Well, neither the PF or PNF demonstrated any sign of experience with regard to the speed scales and the VSI. They may well have received the training, but demonstrably it was something they failed to 'take onboard'.

No - that display only appears if air data from the pitot system or the ADR is unreliable or unavailable. With overspeed I think you see a red strip appearing to the right of the speed tape and the speed is displayed as normal.

jcjeant;

Thanks, now I see!

Below is an image of the PFD in Normal Law.

In Normal Law there is a green symbol which resembles an equal sign ( = ) which indicates when the VMO (or equivalent MMO) warning will occur. The symbol is removed when not in Normal Law. The alternating red and black strip is the overspeed regime. An overspeed is the lower of:

• VMO or MMO
• VLE
• VFE

An audible, non-silenceable chime sounds continuously until the overspeed condition no longer exists.

The overspeed warning functions in Normal, Alternate and Direct Laws. There is no speed protection in Alternate and Direct Laws.


http://www.smugmug.com/photos/i-29kd...-29kdLFR-L.jpg

@PJ2 and Dozy
Thank you for clarification

I am an layman in this area, but I've been intrigued by this plane crash, so I have done some researches, in order to explain to myself what had happened up there.

So, what is the situation with the AP? As I understood after the ice on pitot tubes melts, speed indicators went back to normal. Was it possible in that moment to switch on the AP? What is the procedure with AP switching on?

Was the plane simply falling from the sky, or it had also some horizontal speed? As I read the passengers were aware of the plane's loss of altitude?

After the ice from pitot melts (30 sec from AP swiching of, if I remember), all of the cockpit indicators worked normaly and there was absolutely nothing wrong with them?

Was there any chance of recovering the plane if pilot increased engine power, or it was already on maximum?

Why the captain did nothing about stall alarm? I can understand that pilots thought that it was false alarm, but when captain entered the cockpit, he had not any knowledge of what has happened. He entered, the pilot told him he has no control of the plane and the stall alarm sounded again. He never said anything about the stall?

Are the published transcripts full version of what were being comunicated in the cockpit?

Sorry if I am beeing boring to all of you experts

alogo:
The answers to most of your questions are in the BEA Final report, with the exception of the mind reading required to understand why any of the three professional pilots did or didn't do what they did, or didn't, do.

The "why did they do that?" question gets partial answers via estimations made based on what evidence could be collected, as well as what general human factors knowledge has been accrued by the experts in that field.

If you haven't read the final report, I suggest you read it first, and then figure out which remaining questions you have.

It is linked to in various places on this web site in the AF 447 threads, such as here.

John Tullamarine has provided, here, a wonderful resource for more reading and information.
After the accident, and after the unique recovery of the Flight Data Recorder, that information was reconstructed. It appears from the outcome of the flight that neither pilot understood that the airspeed indications had been restored, however, once stalled, that's a moot point until you unstall the aircraft. If you reconnect the AP in a stall ... well, since the Test Pilots aren't required to do that, and thus didn't collect data points on that, the result of that possible action is left open to guess work.

Beyond that, the situation with switching back on the AP is IRRELEVANT.

Pilots are required to be able to hand fly their aircraft in degraded modes. You restore the AP when you are content that you have cleared a malfunction and wish to use its features again. You have to fly the plane.
Yes to both.
If you read the report, you will find that there was a forward vector.
But that doesn't matter all that much after you are stalled.
If you are stalled, your forward velocity simply influences the nature of impact when you crash, unless you make the inputs to recover from the stall and resome flying again. As I and a number of other contributors here have pointed out frequently, being STALLED is NOT FLYING, it is FALLING. Until you aren't stalled anymore, you aren't flying.
How do you arrive at that conlcusion? And how does that matter? They were in no position to do anything about that. The pilots were. And didn't effectively take care of it. :( :{ RIP, 228 souls.
The reconstruction of the event via the FDR seems to show that, however, as I mentioned above, that is IRRELEVANT if the aircraft is stalled, and the recovery inputs to remedy the stalled situation are not made in a timely fashion. It is also of no help if the pilots don't recognize that the instruments are once again working properly. That appears to have been part of how this accident came about.
The way to recover from the stall, once stalled, is to decrease angle of attack.
If you aren't yet stalled, and yet are close to a stall, sometimes/often increasing power (and accounting for the pitch up tendency that the increase in power will give you when using underslung engines) will speed you up and thus by the fact of airflow and physics, decrease your Angle of Attack sufficiently to prevent stall.

Once stalled, it is usualy required to lower angle of attack by decreasing pitch, and as the aircraft unstalls and returns to controlled flight, you'd usually use power to recover extra flying speed and restore altitude.
That's a general approach, each situation will have subtle differences. In this case, once stalled, if you go to TOGA, or Max Power, you may increase the pitch up due to the underslung engines, and make your stall recovery more difficult, not less so. Detailed discussion of this has taken place on these forums, and I invite you to head to the link I made up there (which John Tullamarine provided) and use the search tools he suggests.
Why indeed? If we only knew.

I mentioned above that mind reading isn't something even the BEA can do in their investigation. None of us can either.

It isn't clear that any of the two, then three, pilots ever clearly identified and stated that "the aircraft is stalled" even though the stall warning was going off at various times during this accident.

My own estimate (guess) is that because there was a known airspeed error issue, at least one of the pilots presumed that a faulty airspeed/pitot system would lead to erroneous stall warning.
I cannot prove that, but it's one plausible explanation.
There are others, to include the belief asserted to be held by some people that an Airbus cannot stall. See the various threads for massive amounts of discussion on that little chestnut.
Why indeed?
The answer to that remains in the grave.

The Captain was having to catch up to a deteriorating situation. Some of us guess -- and I say GUESS -- that his brief "this is not possible" comment may have referred to an initial diagnosis of "the plane is stalled" and his unwillingness to believe that his two copilots had somehow stalled the plane in the short time since he'd left the cockpit. But he may have been referring to something else, like the incredible rate of descent.
Apparently not.

There are ten separate threads on these forums on this topic, and a great deal of discussion on that point. See the link I gave to you for page one of this thread, where John Tullamarine has kindly provided many resource suggestions.

Suggest you PM jcjeant on that particular topic, or Lyman, as they are both quite vocal in their disappointment with the full CVR not being released.
Not at all.
Read the final report. Ask questions.
There are some folks who can be of help.

:O

It is inconceivable that the short, clipped phrases from CVR, released by the sole investigator, are the extent of pertinent conversation by this crew.

By definition, what is published is pertinent, and if one trusts the BEA, what is left out is not. BEA are not to be trusted with the rest of the recording.

All of the DFDR is available, unfortunately it does not converse, swear, or think.

There was discussion, in varying tones and inflections, that might perhaps further indict the aircraft?

@Lonewolf

Thnx for answering my questions. Firstly, I don't know why I can not quote posts, maybe because I am new here.

I started to read final report, but it is very massive text, and it takes a lot of time to read it. Not to mention that I am not an expert, and that report contains a lot of "strange" words for me.
I already saw 10 threads about AF447, but when working and having family it is very hard to read all that stuff in short period. I started to research this topic last month.

That is the reason why I oriented to the internet articles, forums and youtube, where the language is much more understandable. I understand in general what happened to AF447, but there are still a lot of black holes for me.

I know that noone can read pilot's minds, but that is why I want to hear something from the people who are also pilots, to hear what were they PROBABLY think, or why they probably done something. Understandably, reports won't say such things.

As I understood switching the AP on was not an option, it wouldn't help much.
I know that pilots were not aware that the indicators are OK, that was the "catch". My way of thinking was: "Nothing helps, we are falling, let's try with the AP switching on". Since I am not a pilot, that way of thinking is probably wrong :)

I watched the video on youtube where one investigator (I assume) said something like: "Most of the people were probably sleeping, so they did not know what was happening". From that (and my experience with traveling by planes) I concluded that passengers felt they were falling from the sky. I felt every time when the plane was decaying due to turbulences. Of course, this issue is not relevant to the air crash, just a little bit of human curiosity.

You said that it was irrelevant if the indicators worked fine, because the plane was stalling. The point is that obviously they did not belive that indicators are OK, because in that case they would believe that they are stalling and they would have done something about it. As I understood, although there was a lack of training with high altitude stalling, the point is that pilots DID NOT BELIEVE they were in the stall. If they belived it, they would have done something about it.

The pilots did not understand what was happening because they did not belive to the instruments, The AP was off, so they belive the stall alarm was also false.
My question here is: Is there any chance in that conditins for pilots to figure out what was happening, just relying on the cockpit view and the feeling? I read that in stall conditions there is some kind of "buffeting".

I did not pay attention to that captain's "It is impossible". So that was probably related to the stall warning as you said.

Another thing. From the last 1/2 minutes or so I conclude that Robert and Dubois realised the plane was stalling, after Bonin reveales that he was holding the stick back for the whole time? After that they were "mad" and try to put the nose down, as I understand.

Do you think that is likely?

This has indeed no importance to technical point of view and therefore this is not even important to the BEA investigation
By cons .. for the trial to come (when ?) it is very important
Be sure that the families lawyers will do everything in their power to demonstrate that the passengers knew that something unusual was happening
The benefits (money) will be greater if it is proved that the passengers knows that it was a problem (mental suffering .. stress .. etc ..)
BTW lawyers will certainly advance that it is because the captain (not in the cockpit but rather in the cabin) realized that something unusual was happening that he joined the cockpit
Hence his question (first words when he is in the cockpit)
What are you doing ?
And not ..(seems more logical for someone who don't know)
What happens ?
It was also some calls by one of the " cabin personnel ? "

jcjeant, being afflicted by fear or mental anguish is irrelevant if the problem was dying, don't you think?

I suppose that the lawyers want to play the drama queens, so perhaps you are right.

As to your attempt to read the Captain's mind:

Given that he had to walk up a 10-12 degree nose up incline to get to the bloody cabin, of course he asked "what are you doing" as soon as he got in, given that he had turned the aircraft over at altitude in level cruise.

EDIT: I may have the time line all screwed up there, the nose may not have been that high as he responded to the call from the LH seat pilot.

Also, of course he asked "what are you doing" when he showed up, since he'd been paged less than thirty minutes after turning over the aircraft to his two subordinates.

He needed to know WTF was going on since what should have been happening was the plane proceeds toward Paris, as they had briefed, at altitude in level flight, at cruise airspeed.

We may also make the estimation that he had not fallen asleep, and that the roll excursions that went on initially had gotten his attention, and he wanted to know WTF was going on with all of this back and forth with the wings when the plane should be level at cruise ...

Yes. If your airspeed is unreliable, AP engagement won't work. (Anyone, please correct me if I said that incorrectly).
Yes, that is wrong. :) Fly the plane, engage the AP once you have the plane behaving as your mission profile calls for.
That is a guess, but a good one.

In ten threads of discussion here, over three and a half years, a good analysis shows that the plane was in a modest nose up attitude and modest bank, for much of the descent and at impact. You'd want to read the FDR traces to see where it was nose high, lower, and how often the roll reached peak values. The nose was somewhere around 11-15 degres nose up when it stalled. Not quite as high at impact.

It seems that the aircraft did not have a significant airframe buffet while stalled. Following that line of thought, you would not "feel" it as with some other planes that shudder a bit more at stall, and when stalled.
Probably not.
Once the plane settled into its descent, the "feel" would return more or less to "one G." The feeling you refer to is due to a transient condition. To apply what you feel as a passenger, you would expect the that the "feel" would be in the transitions, when something changes:
first, the climb before stall,
and then the onset of descent as the stall began.
Once established in the stall, the plane was more or less in a steady state descent.
No.
They knew the indicators were giving them trouble, but you can't automatically infer from a bad indicator that you are stalling from that point of info alone.

A sound instrument scan should have alerted at least one of the pilots of the initial climb. At one point it did. He tried to get the other to "go down." The increasing rate of descent as the stall was manifested and began to take effect ought to have alerted one of the pilots, except for the point made that actual stall recovery on instruments isn't typically trained for. Stall prevention is.

Altimeters and Rate of Descent displays were both indicating a falling aircraft after the stall.
1. This appears to be a contentious point, since the industry has had upset training and understanding of upset for some years. Since certification didn't require exploring the stall envelope, the training is mostly in stall prevention, not stall recovery.
This does not appear to be an issue only at Air France.
That said, if you prevent stall, you don't need to recover from one.

2. Not "did not believe" they were in a stall but "did not recognize" they were in a stall. It can be reasonably concluded that what they didn't believe was the audio warning of stall. But we are indulging in a little mind reading, since not everything they thought is captured by something said on the CVR. Be careful.

3. I agree with this point, others may not.
This is a debatable point. I would not put it that way.
What appears to have happened is their instrument scans broke down, to one degree or another, and the most useful information on the instruments was not what they paid the most attention to.
No. That does not follow. Why they did not address the stall alarm, or comment on it, isn't so simple. AP being off had llittle to do with that.
No. They were flying in instrument conditions at night over the open ocean. You don't fly by feel in that case, you fly using you instrument scan. At least, you do if you don't want to get fooled by feeling and die.
That is a lesson written in blood over decades of flying.
That is a debatable point for the A330. It appears that the A330 doesn't buffet as much while stalled as some other planes do. gums described this as a "mushy" departure from controlled flight. This provisional conclusion was based on some detailed anlaysis of the FDR by some posters here, and I ask you to search that yourself.
Or not. There was so much going wrong that we cannot be sure what evoked that response.
I'll leave that for others to guess at.
The other two may have figured out that they were stalled, but they didn't verbalize that based on what the CVR info we have available. Someone did a great job of reading out the decreasing altitude in the end game, per the CVR, but that didn't translate into effective action to recover from stall.

We have little evidence of an attempt to recover from stall by lowering the nose (some of the more informed estimates arrived at by various pilots here are that recovery would have had to begin somewhere between 12,000 and 20,000 feet to get unstalled and flying again. There were a number of discussions on how to figure that out, and I don't think a single conclusion was agreed.)
I don't recall who, but somebody did try this in a simulator. (Caution: the sims need data points from real flying to create good simulations, and nobody has done test flights of this plane into and recover from, stall.)

Based on the CVR and FDR, there is some evidence that, without saying anything about a stall, there was an advance of the throttles to TOGA that might have been related to the sound of stall warning. Granted, this was probably based on a drilled response for a problem at lower altitude, but once again there is a bit of guesswork involved here.

Look up Unreliable Airspeed procedure for more detail. Lots of discussion on that. (UAS is I think the acronym used in these discussions).

As I noted above, if you aren't already stalled, added dpower might help, but if you are already stalled, that may hurt your chances of recovery.
A lot of things are likely.

What was unlikely was that AF447 fell over 35000 feet to the sea from straight and level cruise flight. But it happened anyway.

You may wish to look into the discussions of Thales versus Goodrich pitot tubes, or pitot probes, to understand why the airspeeds became unreliable and got this chain of events started.

Taking into account that significantly before he reached the cockpit the plane had exceeded the apogee of the trajecory and started decending he might not have felt the incline exactly like in a stable environment due to the fact that the inclined floor started falling and deccellerating at the same time. Must have felt interesting. Tilted floor but no additonal effort for climbing up a 10° slope. The decelleration might have masked the incline to some extent.
This fact might have contributed to the captain not exactly recognising the attitude when reaching the cockpit.
So at least a small portion of somatogravic illusion is conceivable.

That said the combined neglect of all three regarding the attitude indication and VSI still seems incomprehensible. Seems they were so overwhelmed and 'in action' that they never tried to step back and develop a mental picture of where and how they were moving in space.

When the plane reverted to Alternate Law (2B if I remember correctly), engaging the autopilot was not an option. Once latched into alternate law, the autopilot can not be reengaged until the system is reset on the ground.

My only questions still outstanding in this mystery (outside "What were they thinking") is why with several nose-down inputs to the control stick, some lasting several seconds, why the elevators never moved into a nose-down position. With old cable controls, if you put the stick all the way forward the elevators would instantly respond with nose-down movements however, in the Airbus fly by wire, the elevators never got into a nose-down configuration despite several full nose-down stick inputs. They began to move a bit but were still in a nose-up position the entire ride down. I've wondered if there is a cumulative effect with all the nose-up inputs that delayed the movement of the elevators. The THS I understand...since the elevators never moved to a nose-down position I wouldn't expect the THS to move that way either. I've asked that question a couple of times and no one seems to know :ugh::ugh:

Edited to add: Looking back at the traces, there is around 15 seconds of nose-down stick from 2:13:45 to 2:14. The elevator was at 30 nose-up and in that 15 seconds of almost full nose-down stick, the elevator only moved to 15 nose-up. So even though the pilot commands nose-down, the fly-by-wire never moved the elevators to a nose-down position...for 15 seconds!!! As they only had a bit over 4 minutes from start to finish, I find that response time to pilot inputs awfully slow. Granted, by this point, it was to late to recover but if they had begun a recovery much sooner, such slow response to pilot stick input would have made recovery very difficult, especially considering the THS never moved from full nose-up. If it only moves 1 degree per second, that would mean almost a full minute of full nose-down stick would have been required to get the elevators to full nose-down with the THS beginning to move that way at some point in the process. So just how long would it have taken, with full nose-down stick, to get the elevators and THS into a nose-down position??

But as the CPT PITCH COMMAND is for ND the FO one is for NU, except for only 7 of those 15 seconds.
Also for that period the vertical acceleration is already slightly below 1.0 even with the elevators in a still UP position therefore the pitch law in force at the time is honored versus the request.

Direct Law would have been my choice too ... and also mainly for leaving the trim alone in the first place.

What is happening in that Airbus if the inputs from the pilots are opposite?
I saw comments like "dual inputs" in the reports. Does this mean that one pilot is giving nose-up inputs, the other one nose-down?

What is happening in that situation, who does the plain "listen"?

The plane averages the inputs. If you are pulling nose up six degrees, and Im an pushing down six degrees, the plane will be about nose level.

Remember, the design and intention of this aircraft, a multi crew airline transport aircraft, was based in the law/rule (and common practice) that only ONE pilot is in control at a time. Rather than letting the sysetm go ape if two pilots "fight over the controls" the aircraft system enforces electronically, via the flight control system, a disincentive to have two people trying to fly at once. That's not that bad of an idea, actually.

Since so much of the flight control movement is via computer, electronics, and hydraulic linkages, two pilots puttting contradictory inputs in at the same time could well break something.

That would not be good, when it comes to flight controls.

PuraVida:
Thank you for the more precise and more accurate statement. :ok: I had forgotten the latching in 2B.

algo, what that means in layman's terms is that not only will AP not function when certain data is unreliable, like airspeed, (the computer for the A/P has a logic function that detects conflicting data and at best avoids applying bad data to flight control inputs), but in the case that the degradation takes the plane into a control law called alternate 2B, you can't even put A/P on until you get to the next landing and maintenance facility and have the various features checked and reset.

Again, you don't actually need Auto Pilot to fly. You can fly the plane without it. (It's a bit more work for the crew to do so, however).

In other control laws and modes, you could reset it in the air once the airspeed data problem gets sorted out.

You are welcome to search Control Laws in the series of threads on this based on the link I gave to you for page one of this thread.

A great deal of very educational discussion was posted here regarding how A330 Control Laws work. These aren't the AutoPilot per se, but the compbination of mechanical, electric, hydraulic, and computer driven inputs to the positioning of the flight controls as a response to pilot action, or level of AutoPilot pilot assistance selected for a given phase of flight.

I'm certain that the pilots of the AF447 had read and learn it time ago before it was posted here
However it does not have served them a lot to regain control of the aircraft
I think they had to learn other things .. or they had already learned it .. but forget it just when they need it so much ..

jc, your opinions aren't helping explain this to a layman.

The dual problems of training and proficiency have been beaten to death. I am trying to make neutral and helpful replies. Where I fail to do so, please help explain to this layman.

Our friend algobotur initiated his inquiry with a seeming belief in AutoPilot as a tool and a fail safe. I have tried to explain to him how that is an invalid approach to take in understanding this tragic accident.

The core flying principle involved in my explanation to a layman is that you fly the airplane, and use various AutoPilot features help you in doing so, or in managing your task load. I suppose we should explain that AutoPilot is required for use as much as possible by many companies since they find fuel (and thus cost) savings from modern automated flying tools.

I suppose we can then explain that if the pilots, like our departed friends in AF 447, spent a great deal of their flying time monitoring the function of AutoPilot rather than flying themselves, the sharpness of their hand flying skills may have eroded. I think it's fair to say that many pilots believe that industry wide situation contributed to this accident. But that's also a conclusion with significant discussion and debate remaining.

It ought to be a major point of concern to the airline industry, since the pilot is expected to fly the plane regardless of how many sub systems are acting up.

Whether or not Air France, and its pilot training and quality programs, are about the same as, worse than, or better than the industry norm is to me unknown, and may be unknowable.

Dual Input
 

A couple of posts ago, somebody asked about inputs by both pilots at the same time.

Actually, the reaction to such a situation by the aircraft is not so different in a Fly by Wire Airbus than in any other aircraft.

If in a yoke equipped aircraft, one pilot pulls the yoke with a force of 30 Newtons and the other pilot pushes with a force of 15 Newtons, guess what, the strongest force wins and the yoke moves in the pull direction.

In an Airbus, this happens electronically: 30 N pull minus 15 N push is equal to 15 N pull.

The difference is - electronic addition is not felt by the pilots, they do not feel that the other guy is also handling the controls. With a yoke, you can feel whether the other guy is interfering with the controls.

One sidestick at the forward stop and the other at the rearward stop equates to both neutral sticks regardless of the force (pressure/torque) applied, does it not?

"One sidestick at the forward stop and the other at the rearward stop equates to both neutral sticks regardless of the force (pressure/torque) applied, does it not? "

Yes, that's correct. I don't think the example using control columns is quite correct but I know what the poster is getting at. In the example, the CC would move in the direction of the greater force and the airplane would respond according to the extent of the movement which would, in the example, continue until the CC hit the stops (commanding full-up control deflection), while in the Airbus the SS movement (in degrees) is algebraically summed and the output to the flight controls is that sum. In the case where the sticks are at full deflection but in the opposing directions, the output commanded is neutral and no control deflection occurs.

The fact that the other pilot cannot know what input is being made and therefore cannot make correct assessments as to aircraft handling is the reason why dual inputs are prohibited. The correct procedure is to press the takeover button which temporarily locks out the other sidestick. Keeping the button pressed for (IIRC) 45 seconds locks out the other sidestick until landing.

Even this definition is not strictly accurate (pedantic .. lol)
If it was really the sum of the degree of displacement of the joysticks .. when both joysticks are in the same extreme position the output (deflection) should be double that obtained with a single joystick ... which is not the case .. so it might be simply that this is a algebraic sum if both joysticks move in the opposite direction ..

No jc the inputs are always summed even if they are in the same direction, however the output is limited to full deflection.

Thus 1/2 NU+ 1/2 NU= full NU, any further NU deflection of either sidestick causes no further effective input.

Source: smartcockpit.

Try actually doing some reading before expressing an opinion, will you? You're reminding me of anothe very opinionated guy who had to "refer to FCOM" to find out how the airbus AT behaves with the lever out of climb...

Thx for the AP answers. So, AP switching on was not an option at all. It was also technicaly impossible.

The other thing, what was the situation with the AF447 radar? They were obviously flying thru the storm, why they didn't go around it? As the transcripts say, Robert said to Bonin something like "don't you want turn to the left" and then he turned to the left, but obviously didn't avoid the storm.

In one video I hurd something that this radar also could be misfunctional?

I know all of these questions are probably answered in the Final report, but this is much more easier way for me to have the answers:)

They did in fact make a course deviation, but the freezing up of the pitot tubes was not due to being in a "storm" per se, it was due to the character of frozen water droplets at altitude and a pitot tube that wasn't as able to handle that problem as other pitot tubes one could equip an aircraft with.

You will need to go back to threads 1, 2, and 3 and read about the in depth discussion on the radars and pitot tubes to help flesh out this answer.

Remember this: passenger aircraft flying at similar altitudes carrying hundreds of passengers cross through the ITCZ every day and don't crash.

"They flew into a storm and crashed" is a red herring.
If you bother to read the history of this investigation and this flight, a few things become apparent:

1. The pitot tubes (all three froze up) were scheduled to be replaced in Air France aircraft, and some already had been, but had not yet been replaced on this particular jet. There was an airworthiness bulletin to that effect published a some months (years?) before this accident.

2. The pilots had already slightly reduced speed to account for flying through/near a storm and expected turbulence before they ran into that pitot icing problem.

3. The pitot tubes being rendered unreliable for a short time due to a particular kind of high altitude ice crystals made for unreliable airspeed.

4. The procedure for dealing with that at high altitude appears not to have been followed. That said, the UAS procedure has come under review since that accident. Many discussion on how to train for that malfunction have been recorded in the threads, on this topic. Use the search function on page on to find them.

5. Even with a less than stellar response to the UAS problem, a great many pilots who have years and years of experience flying that route will tell you that setting the correct pitch and power for the altitude and speed desired will keep the plane mostly level, at cruise, until the crew can sort through the malfunction and get the various systems back on line.

Point 5 is a pilot thing, not a machine thing.

While there was a machine malfunction, the pitot tubes taking time off due to ice crystals, most machine malfunctions have a series of procedures and remedy that the pilots apply to mitigate their impact, and to restore performance. The UAS procedure is one such remedy procedure.

The core pilot problem was in not applying the simple measure of flying an acceptable pitch and power while the NON-flying pilot would work through the systems to get them back on line. A contributor to that problem in this case seems to be the lack of hand flying time a lot of air transport pilots get at altitude in many fly by wire jets. If you don't practice something, your skills will be rusty when you need them. This is, based on the inputs of many professional pilots who post here, an industry wide problem.

The core machine problem began as all pitot tubes failing to function (even though there are three to provide redundancy), in part due to an already identified sub-par set of tubes being installed and not yet replaced by better tubes. Airspeed indication and input into the flight system is a crucial bit of information for both pilots and computers to use when flying the aircraft.

The radar don't really enter into it. The judgment call on how far to deviate from a given weather system is just that, a judgment call. Feel free to read the hundreds of posts on that element of this accident. The opinions among those who fly big jets for a living varies a bit on that point.

With that in mind, many experienced pilots note that some of the other intercontinental flights that night had deviated further around the weather system than AF 447 did. The analysis of the FDR data, once it was recovered, didn't show a significant amount of storm associated turbulence to have been a factor in the flight departing controlled flight. (Stall is a departure from controlled flight).

6. There were 32 incidents in the years previous to this mishap of unusual aircraft behavior and upset that were somewhat similar to, though not identical to, the malfunction the AF 447 crew ran into.
None of the others crashed, though some of them had bizarre altitude excursions that they had to deal with. A Qantas flignt (QF 32?) is one you might want to read up on for its similarity to the AF 447 accident.

Once again, please read the report.

Quote from Lonewolf_50:
"Once again, please read the report."

Good advice....

You could read it slowly ten times over, and analyse the DFDR traces at length, in the time it would take to read all the AF447 contributions - good, bad, irrelevant, bigoted, open-minded, pig-headed, inquisitive, perceptive, indifferent, and even brilliant - on this forum.

And that short list of adjectives could no doubt be amplified.

... And also by how much he's interfering with the controls. It is direct first class information.

Electronic addition can take place without aural warning too ...

Not necessarily until landing as a deactivated sidestick can be reactivated at any time, by momentarily pressing either takeover pushbutton on either stick.

In fact its a little bit more complicated.

The AP(AUTOMATIC FLIGHT) can be engaged in both NORMAL as ALTERNATE LAW!.

The AP has its own 'law' built in and 'bypasses' the MANUAL control laws inside the FCPC(aka PRIM).

The AP commands direct flight surface deflection orders to the FCPC, the role of FCPC in automatic flight is to limit those orders when it 'senses' to be required so and to transfer the surface commands to the slaved FCPCs and FCSCs and their respective servos.

The AP however needs reliable airspeed parameter (to set the gains) and VLS(lowest selectable speed) to be available for operation and that was absent in this case.

Apart from the explained SS algebraic addition:

Due to missing airspeed parameters, the filtergains of the flight control law were set to a fixed high speed value (IIRC 330KT).
This combined with the rather small integral(in time) part of the SS order resulted in this 'sluggish' elevator reaction but as one can extract from the FDR traces the reaction of the aircaft was a negative pitch and a positive Nz as commanded.

Would filter gains apply to Direct Law too ?
In other words, is Direct Law that much 'direct' after all ?

Where ?

CONFiture

"Where?"
At Court, to the Judge.

Autopilot is available to the flightcrew after UAS, Airbus (OEB) directed crews to not select it, as it "may" cause an "uncommanded climb" creating "risk".

It is BUSS that disqualifies A/P, until a reboot, on the deck...imo. Also I think NORMAL LAW is not reselectable post BUSS.

Captain DuBois, in the CVR, made it a point to check the A/P switch, late in the game. Why? Did he cycle it? The CVR reports (CAM) a noise of switch movement? Was he concerned about the "sluggishness" of the elevators? Whether due Bonin's pulling, Captain was obviously concerned about the lack of ND? I cannot find any command from Captain: "Putz!, NOSE DOWN" Can You?
Instead, the command is "Try Climb" "But I have aft stick for awhile..." Elevators were the topic of the day, yet all were at a loss as to continued descent.....

The instruments were alive, and accurate, we think, wouldn't the commander be distressed at the NU along with the 10000fpm descent?

WITHOUT QUESTION, the Captain must have assumed the controls were INOP, hence no NOSE DOWN response from the A/C. Where is evidence of his dilemma as to no ELEVATOR control? If he considers Bonin competent to fly, he can have no other conclusion, nor can Robert, who has been privy to the a/c PITCH migrations, from the outset.

Captain not once looks at Bonin's stick, just to make sure? Baloney. Something is fishy here. Robert is satisfied that the a/c is at fault, he must be, he agrees with Bonin "We have lost all control". Not a peep about the climb when DuBois returns?

As to CVR. Failing a release of the (complete) record, perhaps the BEA would consider releasing the audio portions that were transcribed.

Why not? The words are released, why not the voices along with them?

Any guesses?