roulishollandais;
The pitot message was one of five fault messages (intended for Maintenance only - not presented to the crew). It is a Class I (of I, II, & III), Mtce Message and as such would require consultation with the MEL prior to the next departure. The pitot system itself did not fail in a way that was sensed by the FWC but due to blockage was providing erroneous data which was sensed by the EFCS2, (discussed in IRI, ppg 54, 55). The message is not an ECAM Level 1, 2 or 3 message and therefore would not have shown up on the ECAM because there was no "failure". If pitot heat itself had failed, a Level 2 message would be generated and it would show up as an amber message on the ECAM.

Whether this would have helped the PF comprehend what had happened cannot be stated. There seemed a predisposition to, and a determined focus on, certain actions in which the PM was unable to successfully intervene.

As to displaying an ECAM message with the abnormal, "Unreliable Airspeed" followed by suitable responses I cannot see that occuring within the current established ECAM philosophy. The reason is, I think, straightforward: The ECAM is a systems-abnormality page. It, and the Status Display page are intended to secure the aircraft systems for further flight within the limitations of the abnormality including performance additions or limitations where applicable. The ECAM system is not intended as a guide on how to fly the aircraft in certain abnormal circumstances - that is for the training regime to establish through the usual familiar ways.

Life is so much easier in a Boeing if UAS situation happens at altitude in cruise. Just keep the same attitude and power you had and get out the UAS check list. If the altimiter and VSI work you are even more golden. Not a real emergency at all. Just fly the airplane.

But what is the THS setting already when the elevators reach 5 - 6 degrees NU for the airplane to stall at the 10 deg of AoA time 02 11 00 ?

You may as well disregard the following BEA comment on P187 :
Still, if the guy has direct law, he may as well bring the airplane to the stall, no question, but what do you make of the following ?

THS is still at 3 deg and the stall cannot be that developed so the indicated airspeed won’t go below the threshold to silence the stall warning that will still warn when the captain is back. Of course if that captain had the chance to naturally contemplate what kind of input is made by the PF on the flight control commands … that could enormously help him to positively evaluate what’s going on here.

What many here like to call 'graceful degradation' had nothing of graceful during that night.
That law that trim and that sidestick concept worked against that crew that night.
To that list of course I should have added that stall warning logic.

You did not comment ?
No one did ...

FBW interference with "natural" law
 

Well, I shall comment. I know that Doze will bring up operational requirements and such, but I maintain I can contribute to the discussion.

It comes down to the control law implementation and then the natural stability of the jet.

Ours was negative static stability until about 0.95 mach. So the FBW system kept the pointy end forward. This is not the case with the 'bus. The thing has positive static stability unless the fuel transfer system goes awry. But HAL tries to provide a neutral speed stability ( no regard for AoA) and also corrects the basic gee command for pitch attitude. So the BEA comment is correct, with the exception that it should mention that the 'bus has inherent longitudinal static stability. In other words, go to "direct" law and the thing flies like most planes we have all flown ( not the Viper, which would be impossible without HAL).

Without some sort of stick pressure corresponding to the commanded gee as the jet slows down, then it becomes unclear as to what is happening. FOR THE ONE THOUSANDTH TIME....AoA is very important. AoA is what keeps the plane flying. So our primitive FBW system ( for the benefit of Doze, heh heh) had a neat AoA limit that kept you from stalling unless......... If you climbed at a steep attitude and reduced power, you could reach a speed where those air molecules and full nose down horizontal tail positions were not sufficient to prevent entering the stall. A true "deep stall", it was, due to our cee gee and pitch moment at 40 degrees AoA or so. Does this scenario sound familiar?

I disagree with the BEA terminology with respect to stability. The basic aero of the 'bus is fine. It's the FBW interference that makes the jet seem like it has neutral speed stability and static longitudinal stability. Go to "direct law" and you have what all planes have had since Wilbur and Orville flew the first one. Could be "touchy", but the sucker would try to achieve the trimmed AoA, and AoA is what planes use to provide those liftie doofers.

I do not recommend that the 'bus go from full laws to "direct law" willy nilly. But seems to me that a few practice sessions in the real jet in "direct law" would provide a lotta confidence to the crews and also show them the inherent characteristics of the jet.

The airplane stalled at the 10 deg of AoA time 02 10 57. The THS was then at -3.5 degrees. Elevator 5 - 6 degrees should be read as equivalent elevator angle for THS = 3 degrees.

BEA quote: However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at constant thrust. Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick. It appears that this absence of positive static stability could have contributed to the PF not identifying the approach to stall. (End of quote)

The BEA comment is correct, of course. But in the circumstances of AF447 it is mostly theory. It applies if you approach the stall slowly, in still air at low altitude gently manipulating the stick so that you can feel the stickforce increasing the closer you get to the stall. The subtle change in stickforce characteristics hardly matters to a stressed pilot who jerks the stick backwards to increase pitch from 6 to 12 degrees in a couple of seconds. I quantified the difference in terms of stick angle and force.

I agree with the first sentence, and wrote essentially the same in one of my recent posts. Regarding the captain, the stall warning is loud enough to be heard through a closed cockpit door. The captain must have heard it when he entered the cockpit.

CVR transcript
The captain heard the stall warning ... an if he was in the rest station (who is just side the flight deck) he will have heard ( trough the wall ) this ( loud ) warning from about a minute ..
Of course .. as I'm certain .. he was not in the rest station .. unfortunately ( bad luck again ... )
In fact .. nobody know where he was ... not Robert who bell him and ask frantically for the captain return ... nor the BEA ....
And it's not Bonin preoccupation ... he have the hands full and more ....
Maybe shame for him but the best was that Robert make a general call "the captain is requested urgently in the cockpit" ... :(

Wouldn't that also work in other types, including the FBW Airbuses?

Indeed. Several Airbus (and non-Airbus) guys advanced the fact that if the crew had left the controls alone for a few seconds at the point of autopilot disconnect, power and trim settings would in all likelihood have been maintained.

Your experience makes you the most knowledgeable man here around on FBW and flight control laws.

Do not lose of sight that direct law is already practiced for every single early part of takeoff and every late part of landing by an Airbus pilot.
Direct law is also active after a number of malfunctions, which are encountered during usual training.
Direct law has been practiced during the initial training when only one Flight Control Computer was left ON to demonstrate how the Airbus behaves as a 'conventional aircraft'.
Also some exercises as LOST OF ELEV and MANUAL BACKUP go further that direct law as the main way to control pitch and overall performance is done through the THS ONLY (stick useless for pitch control).

Just to mention that direct law is not that wild thing.


But what I’m more interested here is how direct law would have simplified the all situation of AF447.

You know better than that HN. You told me the other day I was maybe 'evading' the issue, it was not justified and as soon I could properly get what your point was, we were able together to bring the subject further.

So it is my turn to question : Are you evading the points of discussion ?

I don't think that I am evading any point of substance. I do have the feeling that, having clarified the facts, our discussion has reached the point were remaining differences are matters of opinion. Regarding matters of opinion, I am always reminding myself that I am an engineer participating in a pilot's forum. If there is a technical point to discuss, please be more specific.

I'm probably in over my head here, maybe you guys are talking about some deeper issue, but....

I never tried to stall a transport category jet above 17500ft, so I must speculate, but I think you over rate the "subtleness" of stick force characteristics. I'll leave it up to the more research minded among us to find the regulatory standard, but if memory serves there is a minimum value of stick force per knot of deviation from trimmed speed. For the simple minded pilots out there, including me, that means that it takes an ever increasing amount of stick force to fly further and further away from trimmed speed. If the aircraft is trimmed for M80/260KIAS, and the pilot slows down, he must exert an not insignificant amount of force on the stick in order to maintain his new speed. Assuming of course that the aircraft does NOT trim automatically.

I think the BEA wording that you quoted is correct, and it is correct all of the time. It matters not whether you enter the stall from low and steady, or from high and unstable (flight path), either scenario in a "classic aeroplane" (BEA words) requires increased stick force to move and hold the airplane in the slower, approaching stall, situation.

The Bus, offering ZERO control feedback, denies its pilot, completely denies its pilot, this time tested tactile clue to airspeed.

The point I want to make is simple, in our scenario but in a "classic aeroplane" the pull necessary to stall the airplane would not have been "insignificant". In our scenario in the accident airplane, the pull force necessary to induce a stall was apparently "insignificant".

Maybe your sim instructor know tricks mine does not, but an Airbus MIA A320 Simulator with only one ELAC/SEC/FAC on handles like a truck with malfunctioning power steering and broken dampers.

The only way my instructor could force Dir Law left us with no roll control spoilers, slow ailerons, and resulted in an extremely unresponsive airplane.

Direct Law, in the manner some desire, would offer full control of all control surfaces, as its name implies, directly.

TTex says...

"The point I want to make is simple, in our scenario but in a "classic aeroplane" the pull necessary to stall the airplane would not have been "insignificant". In our scenario in the accident airplane, the pull force necessary to induce a stall was apparently "insignificant"."

The pull force to induce STALL was certainly insignificant, and may I also add, 'irrelevant'. The aircraft wanted a gee, and found it, since at post STALL "free fall" it had it. at terminal velocity, the THS appeared content with one gee.....

The pilot input was never exactly in command. To be in command, one needs data, and shy of its full quiver, (notwithstanding the hue and cry re: instruments, which are not known, never will be...) PF had a STALL warn he was ignoring, feel that was not there, and a load of confusion that appeared in the form of FD.

People insist he had a Pitch cue, possibly so.... The CVR has the answers, probably in the "deemed irrelevant" category.... Captain heard the STALL warn plus cricket, he said nothing? My ass.....

Yes it would but my neighbor Airbus captain said he might have done the same thing. What does AB training teach these people?

bubbers44;

Your neighbour Airbus pilot likely has access to the Airbus-produced Flight Crew Training Manual. The FCTM has very clear guidance on how to handle the UAS abnormal and/or ADR failures.

The following, from an FCTM in early 2007, is the essential part of the response:

PART 1: MEMORY ITEMS
If the safe conduct of the flight is affected, the flight crew applies the memory items. They allow "safe flight conditions" to be rapidly established in all flight phases (takeoff, climb, cruise) and aircraft configurations (weight and slats/flaps).The memory items apply more particularly when a failure appears just after takeoff. Once the target pitch attitude and thrust values have been stabilized, as soon as above safe altitude, the flight crew will enter the 2nd part of the QRH procedure, to level off the aircraft and perform trouble shooting. This should not be delayed, since using the memory item parameters for a prolonged period may lead to speed limit exceedance.

PART 2: TROUBLE SHOOTING AND ISOLATION
If the wrong speed or altitude information does not affect the safe conduct of the flight, the crew will not apply the memory items, and will directly enter the part2 of the QRH procedure.

Airbus also produced the following in September, 2006:

http://www.iag-inc.com/premium/Airbu...ableSpeeds.pdf

Hi PJ2,

Thanks for the link to ppt.
Can you please explain why both the QRH and ECAM in slides 19 & 20 say to turn the FDs OFF, (that action was not accomplished in AF744) yet the diagram clearly shows the FDs ON and with no pitch guidance annunciated.

Where has basic training gone? Has automation made them robots? I hope not but in this case it did.

Nice catch!

No, I can't explain it but the indication is inconsistent - there is no "1FD2" or "--FD2" or "1FD--" in the FMA displayed yet as you've observed, the FD is "ON", (shown in the HDG-V/S mode vice FPV symbol and FP director).

It's not the first time I've seen oddities and inconsistencies in training materials though, and this one appears to be in development - who knows what its history is. The qualifying condition "Safe conduct of the flight affected?" is shown, "Defined during training" so there's obviously other training associated and a narrative that goes along with this one.

BUSS requires the 3 ADR's be physically deselected.

It's basically a recover (land) the aircraft and optimized for the approach mode.

Does the ISIS not have ILS capability with an ISIS FD?

...would this be similar and account for the limited FMA annunciations?

LOC* & GS arm are what's displayed...

Interesting.....and weird

edit: I would have sworn lateral and vertical are reversed on the FMA, but beer can create a feeling of more knowledge than one actually possesses. :)

Forgive my direct question but should not the PF maintained wings level pitch and power settings for unreliable a/s. Damn Airbus, seems like both pilots were more concerned with interpreting ECAM failures than flying the damn plane??????Don't think this would happen with analog pilots in an analog aircraft or simply an analog pilot reverting to simple piloting skills. Why would you even trust FD in this event?

I understand the panic in severe turb.

Having said that, I suspect the pitot's froze up due to insufficent heating, possibly as a result of insufficent pitot heat. Wiring, pitot elements.. I question?? Not enough lead in the pencil is my question as the pitot probes go..

This instrument (virtual BUSS) is present and works even when the 3 ADR's are activated :)
It handles all kinds of protections AOA of the Airbus (Alpha prot .. Alpha floor .. etc. ..) in normal law :ok:
This instrument is hidden .. pilots do not see him :rolleyes:
The problem is that when the aircraft leaves the normal law ... this (virtual) instrument stops working :uhoh:

Why Airbus in particular? Are modern flight decks on other types much different? Did "analogue" flightdecks provide better information in unreliable airspeed situations, for example?

I'm sure I'll be labelled an Airbus "fanboy" by some but, as someone outside the industry, I guess I'm just having difficulty understanding why an incident with a FBW Airbus prompts so many to crawl over the entire design to find fault while similar incidents involving other types (e.g. inappropriate reaction to stall warning, loss of air data) result in more focus on crew actions. Oh well, I'm here to learn.

I can't vouch for this particular series of threads but elsewhere the discussions seem to indicate that the Thales pitots used on AF447 met certification standards but not by as much of a margin as the later Thales and the Goodrich pitots. It's also my understanding that there was no indication of any electrical fault.

Did "analogue" flightdecks provide better information in unreliable airspeed situations, for example?

You're missing the point or misunderstanding the problem a little, I think.

The older style aircraft (which happened to have analogue kit due to the available technology) generally were crewed by pilots who did a lot of hand flying - often raw data (ie without any "helpful" gadgets) - and didn't need autopilots, flight directors, and autothrottles to think for them.

Even with such gadgets, we tended to "look through" the flight director, for instance, and fly much the same as we would without one using the old-fashioned I/F scan processes - the flight director helped a bit by assisting the on-the-fly decision processes but was not followed blindly and without pilot thought.

Hence if an ASI problem arose, we just kept doing what we had been doing without the use of one of the usual set of information sources .. just meant we paid more emphasis to pitch attitude (on the AH or whatever term was used for that installation) and engine thrust settings .. and it all just sort of worked out fine.

However, maintenance of the skills required practise. The risk in modern aircraft is that these skills are lost.

Fair enough, but my main point of contention is: why "Damn Airbus" rather than "Damn modern flight decks"? Why "Damn Airbus" rather than "Damn modern training that apparently doesn't make appropriate use of pitch and power second nature to every crew in the absence of airspeed data"?

Oh, indeed .. and you are absolutely correct.

Mandatory RVSM with its potential lowering of the bottom cruising level makes it difficult for pilots to manually handle their aircraft at cruising levels. It ought to be possible for Air Traffic Control to release aircraft from this requirement for a finite period when and where ATC can allow. Not all airspace is always busy throughout the 24 hours. ( A simple example is the Aeropostal night flights from Paris, when and where much of the area is virtually empty. )
Not all flights are from busy areas or at times when they are busy.
( On another thread someone mentioned that their airline arranged that their pilots did two sessions of manual flying as well as a further couple of sessions in the sim doing all the mandatory stuff, annually.)
Some of the " analog" aircraft tended to have higher weather minima ( when these were laid down, I think, in the 1950s). One Captain used to say that he would overshoot when he saw his F/O "BRACE"... But he may have been joking !

In 1975 when most Jet cruising levels were 2000ft apart, in discussion with the UK Authorities, I was told that they were considering reducing this to 1500ft to allow more flights to cruise nearer their own optimum levels.

DL-EDI
 

Not my intent (Damn Airbus) that is. Damn ECAM should have been the statement, it seems like it did more harm than good in this situation. I do feel though that the Airbus ECAM system is like the nagging wife who won't just STFU. It is the pilot's responsibility to fly the aircraft, it seems obvious to me that the PF as John and I had stated was not able to revert to simple pitch and power flight. Disconnect the automation, ignore the flight director.

As for the pitot tubes, I have my doubts. I do know that AB is big on using the smallest gauge wire possible for weight savings. A good heater draws current. Just a suspicion of mine. I will post on eng and tech as I do not have access to A330 WDM's myself. I have been curious what gauge wire the heaters use.

"Do you really believe the PF would have felt the difference in his erratic movements of the sidestick?"

As elevator deflection is proportional to stick deflection, any erratic movements of that stick tend naturally to disappear especially when speed is still high or a price has to be paid on the human body.
Direct law allows the pilot to be more aware of the consequences of his inputs on the stick.

THS at 13 deg instead of 3 deg is an elephant in the room.
Direct law would not have allowed its presence.

Any release of the stick, not to talk about push command, would have provoked an immediate ND change in the attitude.
Direct law would not have allowed to go that easily to the stall and would have favorized an exit from that stall.

"Regarding the captain, the stall warning is loud enough to be heard through a closed cockpit door. The captain must have heard it when he entered the cockpit."

There is no doubt the captain has heard the stall warning, but more than anything there is no doubt the captain has heard the stall warning STOPPING which played enormously in his inadequate evaluation of the situation.
Direct law would have prevented that warning to erroneously quit.

Last point but not the least, the sidestick concept did hide to the PNF initially, and then to the captain + PNF what the PF inputs were and how those were inappropriate at times.


All those points had to be thouroughly developed by the BEA, and not only superficially for some and completely ignored for others.
As written earlier, that law that trim that stall warning logic and that sidestick concept worked against that crew that night.

I can’t tell for the 320, but for the 330, according to the flight control architecture, PRIM 1 or 2 maintain one pair of ailerons + 1 pair of spoilers for roll control + both elevators.
I have no memory of sluggish control, but would have probably to experiment it again.
That would be a great thing, one simple guarded switch to force direct law. But I don’t see that in the Airbus philosophy where the airplane is supposed to take care of the pilot, not the pilot to dare doubting the technology …

Max roll rates of 25 degrees/s in Direct versus 15 degrees/s in Normal would seem to indicate the 330, at least, is more responsive in Direct.

THS 13 versus 3:

During specified sim stall QTG's (Direct, fixed THS), with SS full aft, AOA's run about 15-20 degrees less than the FDR values from the report.

As might be expected very similar to, for example, 727 or 737 AOA values. FPV if selected never leaves the PFD display FOV at these values.

PJ2....thank you sir, for your kind and weighty response. I am giving it the time it deserves, and the state of my brain allows. Your patient responses are waypoints on a voluminous journey.

TTex600.. INRE: Poor technique, "Mayonnaise", and "bump and suss". I think it may be more prevalent than we think? It looks suspiciously like an evolved and ad hoc response to Airbus flight controls....

It resembles "Pilot induced turbulence". Over controlling to goad the aircraft into giving up some feel, as it were. Or to make "minor" corrections in flight path?
As per FCTM? Unusual it has received little attention here. In other aircraft it would not make it past first flight in type?

You have seen it? Could you enlarge on your experience with it? It seems horrendously out of touch with such a sophisticated airplane and her philosophy?

Similarly, it presents as reactive and defensive....no one would fly a Boeing in similar fashion.

Agreed, with the addition that the AirBus integrated FlightDirector/AutoThrust system REQUIRES one to follow the FD's otherwise the AutoThrust becomes confused. This characteristic, that is Airbus specific I believe, forces the pilot to concentrate largely on the FD. That FD "focus" requires that Airbus training is largely void of pitch/power reliance. In that sense, the airplane is at least part of the problem.

My fix is simple, if you turn one automated system off, get ready to turn ALL of them off. A/P OFF, A/T OFF, FD's OFF. Works quite well.;)

Confiture,

Just to defeat the notion of 'evasion':

Considering the inertia of the airplane, I'm not so sure of that. Perhaps you should try it in your next simulator opportunity.

I suppose you mean that there is no autotrim and that you assume that the PF would not have trimmed manually. At 02:11:35 he seemed pretty desperate to keep the nose up, and in direct law "USE MAN PITCH TRIM" is displayed on the PFD.

In the two instances that the PF released the stick, the elevator responded and the airplane promptly pitched ND.


While it is probable that the stall warning would have been uninterrupted in direct law, that is not certain.

I have earlier expressed my opinion on the visibility of the sidestick. Seeing the control pulled to the back stop might have added another clue that might have pointed the PNF and particularly the captain towards a correct diagnosis of the situation.

Perhaps you would care to justify that opinion considering that BEA's investigations "are conducted with the sole objective of improving aviation safety and are not intended to apportion blame or liability."

That would depend on how the airplane arrived at Direct Law. If it goes direct because of compounded flight control computer failure, you are left with reduced control surfaces and the aircraft response will be reduced. If it goes direct because of something other than computer failure, it might retain full control surface complement and be quite responsive.

I've slept at least once since writing about poor technique, and I'm in a bit of a hurry at present. With that said, "Mayonnaise" differs from the "slap the stick" method to which I refer. Mayo would be akin to full scale deflections and opposite full scale deflections in the opposite direction (made in my opinion due to the lack of a link from stick to controls. Sometimes one wants more roll and ends up at full SS deflection which then requires full opposite stick and back and forth) where slapping the stick is minor corrections made somewhat like a 16 point roll performed by a world class aerobatic pilot.

I brought that up as an example of something the FCTM should discourage vs encouraging.

But for now, I've got to get back to planting my fall garden.

A very much earlier comment, from a couple of thousand years ago, was:
" Do not let your left hand know what your right hand is doing."
Whilst this was related to giving, charity, in aviation terms it could mean information from one pilot to another.
PF was, presumably, using his right hand. PNF was able to comment on stirring the Mayonnaise, scarcely on the use / abuse of NU.
They had a couple of minutes to "Permutate the Possibilities", as a Royal Flying Corps pilot would have put it.

Lyman,

Here are a couple of clips of hand flying a Boeing 737 near landing at lower speeds. In the second clip, the PF is in the left hand seat but you can see the yoke movement over the shoulder of the PNF in the right hand seat . There are no clips of hand flying at altitude or high speeds as the AP does that. I would imagine at higher speeds and thinner air, manual flying (hand movements) of either the stick or yoke would need to be highly finessed (light touch) just as maneuvering at high speed in your car would require so as not to experience LOC. I threw in one Airbus clip just for example to go with the Boeings. Note in the Airbus, you can observe the trim wheels turning as you do in the Boeings.
Cheers!

TTex: Point taken, I'll do a little research...

(There certainly is a lot of RED on the right ND in that NG video. :eek:)

Sorry if already posted (consider as a reminder .. )
Aero 12 - Angle of Attack