AF447 Thread No. 3 [Archive] - Page 2

theficklefinger

28th May 2011, 02:42

So I guess it's completely beyond all the experts in here to fathom the impossibility of an Airbus of the coast of SOUTH AMERICA to be in IMC from 38000 ft to the ground?

Well so much for the pilots trying to 'read instruments' when in fact they were probably in VMC conditions, which begs to ask the question if anyone in that cockpit could, would, or have the ability to simply stop looking at the panels and fly the plane straight and level...which would have required, against all training, hiring practices, and airline SOPS, to DISREGARD the instruments, disengage the autopilot, and just fly the plane...you guys remember that? When flying actually meant holding the yoke and not just moving a heading bug?

And even if, at best the A/S indicator was messed up, you know like the Dallas accident where someone forgot to turn on the pitot heat...in the end, I am sure, they either had an A/I to look at or the ocean for reference, so what exactly would have stopped them from leveling the nose, the wings, and going to a known power setting until they could figure out what was wrong with the tubes they were looking at?

I am almost wondering if another tail came off...

Machinbird

28th May 2011, 02:43

Just a few thoughts on trim.

I've never flown even the 'Bus simulator, but I have studied the systems. (Does the Caravelle simulator count?:}) I'm a retired Naval Aviator and both old and bold.

Yes, the THS is a 500 pound gorilla that can overpower the elevator position.
The THS is controlled by the Prim computers, theoretically any one of the three Prims can do it. Without Prims, it won't move except by manual input.

Recently, I was attempting to clarify some issues regarding THS manual trim (in the last thread), and asked the question, "How does the system know the pilots are done applying manual trim?" Apparently, once it senses the crew playing with manual trim, it gives up and says "Your trim for the rest of the flight." In a normal flight context, this is bad since the THS can overpower the elevator and cause potentially dangerous loss of control or interfere with proper functioning of protections.
The airlines/training establishments apparently consider this to be a very serious safety problem and they apply draconian penalties for touching the trim wheel. As a result, aircrews fly the majority of their careers without touching the manual trim wheel after it is set for takeoff. They almost forget it is there once airborne.

The trim wheel moves as the aircraft trims itself. There are marks alongside the trim wheel indicating its position, and these marks are illuminated so that they are visible at night in a dark cockpit, but it appears aircrews are not even thinking about looking at the wheel for information.

Part of the problem seems to be that the aircraft does not have the ability to resume automatic control of the trim once the microswitch that senses manual override is activated. As a result, crews are taught to keep their paws off the thing. That would result in bad training habits. (Real Airbus guys feel free to correct these statements.)

Next issue. The trim running up to 13 degrees makes sense due to the prolonged nose up stick input. Once a high AOA was achieved, however, the AOA readings and airspeeds were considered invalid (due to airspeed below 30 knots). The PRIMS could not have liked that and were no doubt all 3 disabled by that point. Once the PF started making nose down inputs, the Prims were still disabled and thus the THS did not move from its 13 degree position.. The crew did not get the proper feedback from their nose down control inputs (the stall warning actually came back) and they never saw the trim position due to their past training.

The only way to have saved the day was to get the trim rolled down manually to get the plane flying again.

Apparently the A330 pitching moments were not so bad as to prevent a stall recovery with proper control inputs.

augustusjeremyreborn

28th May 2011, 02:43

But... It should go nose down anyway... Independent of sidestick inputs

Cg in the right place + excessive AoA should always equal pitch-down and a consequent reduction in AoA. Naturally.

Otherwise margins are so narrow...

captainsuperstorm

28th May 2011, 02:47

dont u read my posts...

u can not get out of a stall in the airbus....it s an airbus , not a a caravel or a cessna.

Capn Bloggs

28th May 2011, 02:55

the independence between the two sticks was a mistake or at least a contributing factor of misunderstanding
The Boeing system seems more relevant from a security standpoint and offer better communication between the two pilots (visual and sensitive)

..and would also have helped the captain, when he appeared, to see what control inputs were being made, even leaning over and grabbing the prong himself. I certainly would have.

Well so much for the pilots trying to 'read instruments' when in fact they were probably in VMC conditions,
It was at night, they were in IMC (at least initially, why else did the probes ice up?). Look out the window of a big jet at night, in cloud, and recover from a deep stall with all manner of noise and warnings going on? Try it. Let us know how you get on.

The only way to have saved the day was to get the trim rolled down manually to get the plane flying again.

Mentioned in my just-issued new Boeing stall recovery...:hmm:

VH-UFO

28th May 2011, 03:08

Per BEA initial report - in structured form for clarity.

01:35:15 Radio:TO ATLANTICO - @ INTOL
01:35:46 Radio:FROM ATLANTICO - Maintain FL350...eta TASIL?
01:55:xx Captain awakens #2 co-pilot
01:59:32-02:01:46 Turbulence & WX Briefing
02:06:04 PF notifies CC turbulence ahead
02:08:07 PNF "Go left a little"

11 Seconds elapsed:
=================================================
02:10:05
AP then AT disconnects.
PF I have the controls"
A/C rolls to right.
PF inputs left and nose-up
Stall warning 2X
A/S "sharp fall" from 275 > 60kts Captain's PFD
Same indications on ISIS "few moments later"
=================================================

34 Seconds elapsed:
=================================================
02:10:16
PNF "...we've lost the speeds" "...alternate law"
A/C attitude goes beyond 10 pitch up
A/C V/S indicates positive rate of climb
PF nose down inputs. L/R inputs.
V/S goes from 7000 fpm to 700 fpm
Roll angle recorded between 12 deg R and 10 deg L
Captain's A/S rises sharply to 215kts
ALT 37,500.
AOA 4 degrees
=================================================

02:10:50 PNF calls Captain to cockpit

49 Seconds elapsed:
=================================================
2:10:51
Stall warning
TOGA
AOA 6 degrees
PF "maintained" pitch up commands

Everything up to the point highlighted in red makes sense in relation to pilot inputs vs aircraft situation, even with loss of airspeed indicators. At 2:10:16 aircraft indicates positive rate of climb and angle of attack, pilot corrects by nose down input.

Stall warning sounds at 2:10:51, TOGA applied with AOA at 6 degrees, but PF MAINTAINS PITCH UP COMMANDS, and it pretty much all turns to ****e from this moment on.

Why would you maintain a pitch up command?

JD-EE

28th May 2011, 03:09

As I read that report with tears in my eyes all I can think of is "why?" Why in (censored) did Hal decide the plane had stalled falling from 270 kts to 60kts in less than a minute. That's acceleration that would have shredded the plane. Hal should have disengaged COMPLETELY rather than force the trim ever upwards to try to maintain altitude. It's as if Hal forgot the inertial system was still there and still functional.

That is a very basic design defect that must be corrected. Simply putting on probes that supposedly don't ice is not enough. (side note, sensor_validation suggested an acoustic monitor on the probes to prove airflow - good idea.) The aircraft must recognize that airliners take more than a few minutes to slow from 270 to near zero absent an attitude shift to a very high angle of attack. If that happens auto-trim should be disengaged with the trim left at the last known good value. Otherwise Hal gives the pilots an uncontrollable plane. That means it must think the pilots are there simply to take the blame in an accident.

So that's my unsolicited highly depreciated two cents worth.
{^_^}

mm43

28th May 2011, 03:29

I would like some input on the following excerpt from the BEA report:-
At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have
no valid indications". At that moment, the thrust levers were in the IDLE detent and the
engines’ N1’s were at 55% the angle of attack decreased, the speeds became valid again and the
stall warning sounded again.My interpretation is that the aircraft was in a deep stall and passing through FL250 with RoD about 10,000 feet/min, and even though both engines N1's were 55%, the pitch-down inputs decreased the AoA and the airspeed data became valid. However, that IAS was low and the stall warning activated again but ceased with further pitch-up commands as the data again became invalid.

Without AoA information, neither pilot had any idea in what part of the stall regime they were, and seemed to react as if a return of the SW was indicating Vmo, hence the continuing pitch-up command. So failure at this time to persist with the pitch-down command effectively left them doomed, as even then with the time taken for the THS to readjust (if it was going to) and for the wings to start flying, meant that the chance of reducing the RoD to zero before FL0 was marginal.

It strikes me that no-one on the flight deck realized that the AoA data was only valid when IAS was greater than 60KTS. Even though they went looking for the FPV, it seems it was only after the SW stopped at 2:11:40 plus a few seconds, and therefore to no avail - see ACARS FPV messages timed 0212z. Their final chance to grab the FPV page was missed shortly after 2:12:02 when the stall warning sounded again - meaning valid airspeed!

Do others agree??

Machinbird

28th May 2011, 03:50

theficklefinger
Well so much for the pilots trying to 'read instruments' when in fact they were probably in VMC conditions,As one who has spent quite a lot of time flying at night over water and far from land, there isn't any VMC at night without a bright moon shining all the way down to the water.
It is rare to see lights at night on the surface far out from land and one or two does not help in orientation.

augustusjeremyreborn
Cg in the right place + excessive AoA should always equal pitch-down and a consequent reduction in AoA. Naturally.Nope. The trim held the trump card.

GarageYears

28th May 2011, 03:53

CONF iture

28th May 2011, 03:58

Because without much airflow at really low IAS gravity affects the position of the AoA vane just as it does on the ground? The designers had to choose a speed - they chose 60kts.
Not too sure about that one Tyro ...
Could be an indicated airspeed of 60kts or anything below, AoA probes won't be affected by gravity with an obvious negative vertical speed of 100kts or above.

henra, I don't think there is anything as Alpha Floor protection in case of A/THR failure.
No one would trim up beyond a STALL WRN, how is it possible the Airbus still auto trim after such warning ... !?
Things don't add up here.

Svarin, your comment regarding the wiring (WRG) ACARS message is interesting. You will need to tell us more.

gums

28th May 2011, 04:33

Salute all!

Good to see many of the stalwarts back here later in the day.

Garage! Until we see the traces of the FDR, we won't know if the THS was commanded up by the pilot or Hal. My reading of the manual indicates the THS will stay at last commanded position once system reversion occurs due to Hal's opinion of reliability/validity of several parameters. From then on, the pilot has to move that wheel. So doesn't look like it will continue to move nose up due to pilot stick inputs after Hal is in Alt 2 or Direct law.

Some points/thots:

- The sticks add inputs, so a forward 5 deg on one can be overcome by an aft 10 deg on the other stick. We need to see the FDR trace. Of course, there's the "I have it" button on each stick, and that is another thing I hope the FDR captures.

One pilot here commented about the Boeing approach. For this plane, I would like that implementation. On the other hand, how many times is an IP "helping" the newbie? Or an old salt is "following thru"? Our Viper family model had tandem seats, so I couldn't see student studly's hands or feel his inputs. The computers added the inputs just as the 'bus.

- Several old salts here seem to advocate that some of the reversion sequences and even the "laws" could be simplified. I shall throw my lot in with those folks.

- Warning and caution indications seem to be less than optimum with regards to the most essential pilot action at the time.

- I have a really hard time with the AoA presentation, or lack thereof. The plane seems to have a comfortable range from basic cruise and stall onset. But once things turn to worms with known air data faults that have occurred in the past, I would really like to see what those vanes were sensing. In my jet, the AoA WAS GOD!!! Didn't prevent a deep stall, but you had to work real hard to get to one.

- I would love to fly a 'bus on an approach to stall maneuver. Some jets I flew announced the condition in no uncertain terms - wing rock, shaking, burble, buffet, etc. Others were as smooth as silk with only a slight buffet or buzz ( delta like F-102A or Concorde).

So what kinda feedback does the jet provide that you are treading on dangerous ground?

Are the pilots trained to recognize stall onset without having all kinda warning and caution lights?

and the beat goes on.

Gums sends...

jcjeant

28th May 2011, 05:04

Hi,

Are the pilots trained to recognize stall onset without having all kinda warning and caution lights?

This is a first answer ....
Specific training for upset is not necessary on Airbus Fly-By-Wire protected aircraft
Pierre Baud
Vice Président Airbus Industrie (1998)

john_tullamarine

28th May 2011, 05:12

.. one presumes that that statement is now in question ?

One point bothers me. Putting aside the possibility that the crew was simply overwhelmed by multiple sensory inputs and just could not think straight (and I suspect that we all have been in such a situation from time to time in the box), how is it that the observation of

(a) a reasonably level or nose up attitude plus

(b) low IAS plus

(c) a shedload of ROD

doesn't immediately equal the mental deduction of stall ?

jcjeant

28th May 2011, 05:18

Hi,

.. one presumes that that statement is now in question ? Indeed ...

I do not think that at the next Paris Air Show Airbus representative will make the same declaration to try to sell his equipment ... :eek:

mm43

28th May 2011, 05:34

JT
.... that the crew was simply overwhelmed by multiple sensory inputs and just could not think straightThat is the crux of the matter, and their situational awareness was such that what they saw/heard/felt made no sense.

JD-EE

28th May 2011, 05:42

deSitter, "How would the airplane behave if its fin came off in the zoom? Wouldn't it start Dutch rolling?"

To quote a great philosopher, or at least a prior posting here:

Ohhh, nooooo!
Not again!!

More seriously, can you imagine the sequence of messages if the tail is lost? What electrical lines are broken? What hydraulic lines are broken? How does the airplane not know it's lost it's tail? I should be able to make a modest maintenance note to that effect.

I also note that 16 degrees is a tad more than I envisioned when I tried to place the plane meeting ocean with some forward motion and great downwards motion. When the flat surface of the elevators slams into the water the tail is pushed up sharply. It breaks off at the weakest point aft of the cabin. That tilts the assembly up. But the VS nose is still planted on unbent aircraft. The leading edge and trailing edge literally pry the VS loose from the plane as it hits the water. It probably hit the water slightly to the side and aft of the elevator. When its joints broke it must have rather sprung up into the air quite dramatically.

{^_^}

Machinbird

28th May 2011, 05:49

One point bothers me. Putting aside the possibility that the crew was simply overwhelmed by multiple sensory inputs and just could not think straight (and I suspect that we all have been in such a situation from time to time in the box), how is it that the observation of

(a) a reasonably level or nose up attitude plus

(b) low IAS plus

(c) a shedload of ROD

doesn't immediately equal the mental deduction of stall ? J.T., My initial reaction after reading the BEA document was to exclaim:
"Put these guys flying the Airbus in a real airplane and make them explore the limits."
This airborne simulator that babies them is ruining them!"

But then I wondered what kind of indications the PF had on his panel to make him do such a silly thing. I concluded it was initially probably very different from the side the DFDR was reporting on.

It has been said elsewhere that experiences that do not kill me make me stronger. This is particularly true in aviation.

blind pew

28th May 2011, 06:10

The more I read the more I think there but the grace of god.........

One of the few memory drills I learnt in the 70s was for runaway stabilizer and we had in effect that during this accident. - serious s**t on it's own.

Middle of the night.
Turbulence.
Hypoxia
myriad of warnings - some completely false.

Lack of training.
no ins or gps speed indication.
known pitot problem

I now honestly believe that most of us wouldn't have made it.

I only once used the TURB button on the DC10 - the other crew members were so comatose that they both kept switching the autothrottle back on.

Having flown the route for 6 years and operated in the european country where severe turbulence was an often occurrence I empathize with the poor b*****ds.

But I ain't so in love with guys who sold two crew and incredibly complicated "life saving" aircraft systems to the world.

What happened to the old values of leaving an aircraft's trim to the pilot, followed by if you point the beast in the right direction and add the correct thrust it will go where you want it to!

RIP

JD-EE

28th May 2011, 06:42

Graybeard, "JD-EE: Normally I find your comments/assessment rational..."

That was immediately after reading the report and before reading anything here. The trim simply followed pilot input, even to the point of becoming silly it was so extreme.

Hal betrayed them by failing to recognize the abrupt decrease in the plane's air speed without any control inputs to have caused it. Rather than declaring a stall Hal should have declared something else, "I'm lost in a maze of twisty little lines instruction code and need you to take command probably to fly pitch and attitude for a short while."

The stall warning created a wrong but apparently predictable reaction in the person flying the plane. Grab sky and grab speed.

I understand that in a more rational world at altitude a genuine stall warning means get the nose down and gain speed then get altitude back. But that never happens so it's never trained for, except it did happen.

Between Hal's erroneous stall warning and the pilot's trained in responses there may well have been no way for the pilots to really figure out what was going o and recover - especially so in that nerve shredded cockpit.

edit: Incidentally, this is not a programmer's problem or error. This is a design inadequacy above their pay grade.

{^_^}

deSitter

28th May 2011, 06:46

There should be an engineer on board whose job is to know the aircraft systems in his bones, not to fly the airplane, or at least not primarily to fly the airplane.

-drl

Bienville

28th May 2011, 07:07

JD-EE say: Hal betrayed them by failing to recognize the abrupt decrease in the plane's air speed without any control inputs to have caused it. Rather than declaring a stall Hal should have declared something else, "I'm lost in a maze of twisty little lines instruction code and need you to take command probably to fly pitch and attitude for a short while."Um... are you ok? The plane stalled. That's why the stall warning went off.

The stall warning created a wrong but apparently predictable reaction in the person flying the plane. Grab sky and grab speed. I take it you are not a pilot. At 37,000 feet over the ocean, he hardly needed to "grab sky." -- Unless there was a 38,000 tree in front of him. The proper reply was to drop the nose. THE PILOT failed to do so. Not 'Hal" but the THE PILOT.

I understand that in a more rational world at altitude a genuine stall warning means get the nose down and gain speed then get altitude back. But that never happens so it's never trained for, except it did happen.

1) It was a genuine stall, that's why the plane fell out the sky.
2) High Altitude stalls do happen and they are trained for. The pilots failed to execute the proper procedures.

Between Hal's erroneous stall warning ....It was three stall warnings and all of them were legit. THAT"S WHY THE PLANE CRASHED.

-------------------

Really, if you have nothing to offer but drama laced nonsense, spare wasting the time of people who actually know a bit about how those airplane thingies fly.

jcjeant

28th May 2011, 07:08

Hi,

IMHO it's sometingh wrong in the BEA communication ....

At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".

At 2 h 10 min 51 , the stall warning was triggered again. The thrust levers were positioned
in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of
around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable
horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and
remained in the latter position until the end of the flight.
Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt;
it was then consistent with the other recorded speed. The PF continued to make nose-up
inputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and
angle of attack being 16 degrees.
Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less
than one minute.

At around 2 h 11 min 40 , the Captain re-entered the cockpit. During the following seconds,
all of the recorded speeds became invalid and the stall warning stopped.

At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have
no valid indications". At that moment, the thrust levers were in the IDLE detent and the
engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In
the following moments, the angle of attack decreased, the speeds became valid again and the
stall warning sounded again.

Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less
than one minute.Make the math ... and the result is not "little less than one minute"

blind pew

28th May 2011, 07:09

JD-EE
edit: Incidentally, this is not a programmer's problem or error. This is a design inadequacy above their pay grade

Couldn't agree more - as is often the case in aviation the office wallahs are there because they can't fly and who better to lead the design philosophy team-NOT.

Trident destroyed by BEA management.

They also ordered a bespoke instrument panel for the Tristar based on the Lancaster and Trident.

Fokker 100 navigation system without ins platforms was lethal when you most needed - in mountainous terrain as it dropped out.

DC10 system pared down to absolute minimum by accountants.

and EADs don't understand their own systems - look at the bird that went through the blast deflectors at toulouse -EADS pilot/engineer.

Bienville

28th May 2011, 07:24

Make the math ... and the result is not "little less than one minute"jcjeant... no the math is ok. 2 h 10 min 51- 2 h 10 min 16 is less than a minute.

THEN they lost proper indications a second time... Now whether the crew noticed they were valid for some time in the middle we'll never known. I personally doubt they noticed from the sounds of it.

blind pew

28th May 2011, 07:26

beinville
you are wrong

I trained for minimum loss of altitude assuming that the stall warning would happen on the latter stages of approach - full power and maintain attitude or stop it increasing unless it was extreme.

Automatics
We used to fly military type visual approaches with the engines in idle down to 500ft.
Two F100s had stall warnings on final turn at Nice - both were initially thought to be false as we had been told we had 100% stall protection a la airbus - not true as with a certain FMS selection we could get into an open descent mode without stall protection.
The books were rewritten.

The stalling demonstrations that I carried out on the sim were generally the same as taught in little aeroplanes and not representative of real life.

I had several stall warnings in the earlier part of my career - generally in turbulence and in all but one case they were written up as false which turned out not to be the case.

I seem to understand that the initial stall warning was false?

Again the Stab trim - this was considered so important on a couple of airliners that I flew that it beeped on every rotation of the wheel and we could reach a CB to isolate it if it started to runaway.

rudderrudderrat

28th May 2011, 07:28

Hi All,

If the pilots mistakenly believed they were in windshear conditions, it might explain why the pitch attitude was around 17.5 degs for most of the time, and why full back stick was used to prevent height loss iaw QRH 1.26.

I've seen some crews in the sim simply rely on FBW stall protection (rather than piloting skill) to nibble in and out of the stall warning during wind shear exercises.

Bienville

28th May 2011, 07:36

beinville
you are wrong

I trained for minimum loss of altitude assuming that the stall warning would happen on the latter stages of approach - full power and maintain attitude or stop it increasing unless it was extreme.

Blind Pew, please explain how I am wrong. I hope you are not saying stalls do not happen at high altitude. If so, you might want to google that before you answer.

jcjeant

28th May 2011, 07:39

Hi,

Quote:
Make the math ... and the result is not "little less than one minute"
jcjeant... no the math is ok. 2 h 10 min 51- 2 h 10 min 16 is less than a minute.

THEN they lost proper indications a second time... Now whether the crew noticed they were valid for some time in the middle we'll never known. I personally doubt they noticed from the sounds of it. My understanding of the BEA note is they are not accurate ....
When you make the sum of speed invalid time it's more than "less than one minute"
It's two losses of speed indication
Was better to put also a foot note for the second loss of valid speed.
It's important for the case.

Bienville

28th May 2011, 07:49

No because the notes where in chronological order. They put that note after the first loss of indication. Which is where it belonged.

BTW can you tell me where you got this quote you posted?

Specific training for upset is not necessary on Airbus Fly-By-Wire protected aircraft
Pierre Baud
Vice Président Airbus Industrie (1998) I ask because google has never heard of that quote.... and gogole knows everything. ;)

BOAC

28th May 2011, 07:52

I stand by post#1 here (http://www.pprune.org/safety-crm-qa-emergency-response-planning/379780-computers-cockpit-safety-aviation.html), posted nearly two years ago, and would repeat another post somewhere else that an easily accessible big button on this type of system is needed to enable direct control (assuming, of course, we have pilots in the cockpit and not computer operators:mad:).

There is still, even after all these years and accidents, much yet to be discovered on this FBW system and its failure/reversionary modes which appear to be built on the assumption that 'nothing can really go wrong so we don't need to worry too much about it.' Murphy's law applies.

blind pew

28th May 2011, 07:54

beinville
you say I should google it?
jesus is that where you get your knowledge from?

Fact from personal experience .

All of my stall warnings in airliners have occurred in approach configuration low down in turbulence except for one in a high level holding pattern which was a mach stall.

Besides the obvious factors the margin over the stall is at it's minimum.

Once in initial climb at MTOW we hit minus 20+knots windshear with T/O thrust - procedure was full thrust and +5 pitch or thereabouts.
Speed was below V2.
Skipper followed procedure but speed decreased - he ignored my calls so I got on the stick and gently pushed it to drop the nose a couple of degrees and we started accelerating.(lower drag).

You have to realize that today everyone is taught to follow SOP but they do not always work.

henra

28th May 2011, 08:03

Checkboard; Would the cockpit displays tell the pilot that the THS was at maximum nose-up so that stick aft wasn't helping?

The pilots did NOT fight the trim.
Please read the Report!
They produced/aggravated the trim.
Had they pushed the stick forward the NU trim would have been reduced by the Auto- trim.
There is NO indication of a runaway trim. It seems it was a commanded trim.

Bienville

28th May 2011, 08:05

No I'm asking you why you say I am wrong?

The plane stalled at ~37,000 feet. There was absolutely no reason the pilot had to 'grab sky". Quite the contrary he was too high and (most surly) would not have stalled at 15,000 feet.

Now if you can tell me how I'm wrong, I'm all ears.

AND BTW your training or the lack thereof has nothing to do with this flight.

Pawlos

28th May 2011, 08:07

As I read BEA I was puzzled by THS being in almost full up position for about 3,5 minutes and not changing its position although PF made pitch-down input. Unfortunately report doesn't mention for how long pitch-down input lasted. I took my copy of A330 FCOM (not current one) and found out, please correct if I am wrong, that flight control law could have changed from ALT 2 to Abnormal attitude as angle of attack was greater than 30 deg causing no auto trim available until angle of attack decreases below 30 deg, which according to BEA report did not happen.

https://lh4.googleusercontent.com/-wFnLEAR5AAE/TeCsTkBh1-I/AAAAAAAAABE/beWbODr2E68/capture_28052011_095849.jpg

Is there any indication in the cockpit when this happens?

Bahrd

28th May 2011, 08:08

A qualified A330 type rating instructor talks about what he sees in the initial BEA information. The call asks some uncomfortable questions. The system of airline training needs to take another look but also there is work for Airbus pertaining to pitot tubes. It would seem there was a systemic failure on many levels.
PodOmatic | Best Free Podcasts (http://iagblog.podomatic.com/player/web/2011-05-27T13_17_10-07_00)

MkSi

28th May 2011, 08:10

All

We have a loss of airspeed data because of ice in the pito that lasted for under a minute.

This triggered Alternate Law

After this the pitos came back, with the aircraft in a deep stall

Some questions :

1. Could the auto flight system be re-engaged in the stall ?

2. If so , would Alpha floor pulled them out of the stall ?

Simon

rubberband2

28th May 2011, 08:18

BEA Report – The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.

The last recorded values were a pitch attitude of 16.2 degrees nose-up, a roll angle of 5.3 degrees left and a vertical speed of -10,912 ft/min.

Where is the BEA quoted (THS) trim nose-up angle measured?

Is it an internal computed value displayed on EICAS?

Is it 13.2º on the cockpit pedestal trim wheels?

Is it 13.2º as shown on some aircraft where the horizontal stabiliser (tailplane) leading edge fairing meets the vertical fin?

Or ..... ?

irishpilot1990

28th May 2011, 08:21

Really, if you have nothing to offer but drama laced nonsense, spare wasting the time of people who actually know a bit about how those airplane thingies fly.

It seems the problem is even the best pilots don't totally understand everything about their aircraft! It seems you need to do an IT course not a flight training course for this plane! Then you have the problem of airbus themselves claiming it couldnt stall!How many incidents have occurrd with the computer workIng against the pilots!

Frankly it's like a horror si-Fi movie of robots that try take over the world, the machine thinks it's better then the pilots, and the makers don't understand the complicated rare events, the events that kill.:oh:

jcjeant

28th May 2011, 08:22

Hi,

BTW can you tell me where you got this quote you posted?

Seem's Google is no more reliable .. lol
http://henrimarnetcornus.20minutes-blogs.fr/media/02/01/1718484589.pdf

Bienville

28th May 2011, 08:34

How many incidents have occurrd with the computer workIng against the pilots!

Frankly it's like a horror si-Fi movie of robots that try take over the world, the machine thinks it's better then the pilots, and the makers don't understand the complicated rare events, the events that kill.I'm not sure how this nonsense got started... the computer was not "working against the pilot"... The report today CLEARLY says that all engine controls and input controls were functioning perfectly.

The pilots were working against common sense. When a plane stalls you push the nose down, not up. End of discussion.

Bienville

28th May 2011, 08:36

> Seem's Google is no more reliable .. lol

OK anything more reliable than some guy's blog who today posted a quote that nobody has ever seen before?

henra

28th May 2011, 08:41

The PRIMS could not have liked that and were no doubt all 3 disabled by that point. Once the PF started making nose down inputs, the Prims were still disabled and thus the THS did not move from its 13 degree position.. The crew did not get the proper feedback from their nose down control inputs (the stall warning actually came back) and they never saw the trim position due to their past training.

The only way to have saved the day was to get the trim rolled down manually to get the plane flying again.

Hmmm, looking through all the ACARS and the information we have at the moment I surely must have overseen the part where it was stated that all PRIM's were deactivated. I have seen PRIM1 and SEC1 but nothing more.
Could you point me to the information indicating loss of all PRIM's ?
That would have led to Direct Law btw.
Also I'm missing the part where it was stated that the pilots were vigorously commanding Nose Down only to be overriden by the Trim ?

Bienville

28th May 2011, 08:49

henra one thing I really learned tonight is that people just make stuff up.

blind pew

28th May 2011, 08:58

Beinville
you have to step back and put your thinking hat on.

One of the most frightening and unique generated sounds in a cockpit is the death rattle.

Add the fear, fatigue, disorientation and hypoxia factors to a host of contradictory information then the brain prioritizes.

The crew were faced with false stall warnings, overspeed warnings, control law warning, turbulence, probable dutch roll and a stab that was moving to the aft limit for whatever b****y reason.

I very much doubt if anyone in the crew had ever flown manually at altitude.

The body tenses with stress and fear and primeval instinct is to wrap oneself up in the foetal position - which could have resulted in the PF inadvertently putting a nose up input on the stick while he was sorting out the roll and what was really happening.

They had very little time and whether or not they had any correct speed indications they did not have the time to diagnose what was right or wrong.

Remember the air india 747 which rolled on it's back with a faulty horizon after take off - one instrument failure only.

BA nearly lost a 747 - the LAX one- as the crew didn't understand the basics of the fuel system and that technology goes back to Noah.
They also had the whole night to play around with it and get it wrong.

The myriad of posts trying to fathom out the computer system shows that it is not understood by the average bloke.

pax2908

28th May 2011, 09:03

From yesterday's note from the BEA ... apart from the stall warning ... indeed there seems to be no indication (from the CVR) that they realized they were into a stall? If there was, why would the BEA chose to leave it out of their note?

lomapaseo

28th May 2011, 09:09

One of the most frightening and unique generated sounds in a cockpit is the death rattle.

Add the fear, fatigue, disorientation and hypoxia factors to a host of contradictory information then the brain prioritizes.

..........

The body tenses with stress and fear and primeval instinct is to wrap oneself up in the foetal position - which could have resulted in the PF inadvertently putting a nose up input on the stick while he was sorting out the roll and what was really happening.

That kind of analysis is the last thing I would expect to see in an accident report.

The crew deserves a more thorough analysis

Yellow Pen

28th May 2011, 09:11

I think Blind Pew needs to follow his own advice and step back...

The crew were faced with false stall warnings, overspeed warnings, control law warning, turbulence, probable dutch roll and a stab that was moving to the aft limit for whatever b****y reason.Ten out of ten for drama, five out of ten for accuracy. False stall and overspeed warnings are to be expected wth unreliable IAS. Control law warning - no big deal, alternate law is benign. Turbulence? An assumption. Dutch roll? And assumption. Moving stab? Not an issue. It was functioning as designed and the crew would not likely even be aware of the stab position.

I very much doubt if anyone in the crew had ever flown manually at altitude.I have flown an Airbus manually at altitude. It's exactly the same as flying it at 10,000 feet thanks to the flight control laws, either in Normal or Alternate law. It's not an issue.

The body tenses with stress and fear and primeval instinct is to wrap oneself up in the foetal position - which could have resulted in the PF inadvertently putting a nose up input on the stick while he was sorting out the roll and what was really happening.Errrrr - you don't accidentally put full back stick on, and not for 30 secs. Your arm will get very tired.

They had very little time and whether or not they had any correct speed indications they did not have the time to diagnose what was right or wrong.Thats why you have an unreliable airspeed recall item.

BA nearly lost a 747 - the LAX one- as the crew didn't understand the basics of the fuel system and that technology goes back to Noah.
They also had the whole night to play around with it and get it wrong.

There was never any chance of losing the aircraft, and the issue which manifested itself only became apparent at top of descent and would have resolved itself of it's own accord anyway. Lots of fuss about nothing.

The myriad of posts trying to fathom out the computer system shows that it is not understood by the average bloke. Fortunately 'average blokes' aren't let loose on multi-million dollar airliners. They have to have a lot of training first, which is why many Airbus experienced pilots find this kind of speculation tedious.:ugh:

aussiepax

28th May 2011, 09:16

blind pew

No evidence so far released to consider hypoxia as a factor.

EDLB

28th May 2011, 09:17

I wonder what the investigation will find, why the PF refrained from simply attitude flying. All attidude indicators should have been functional all the time and are the only hope to survive hand flying at night over ocean with partial panel. With the turbulence, roll and falling sensations vertigo had definitely set in. You can't fly by the pants over the ocean at night in a thunderstorm. The pilots had a mostly blue attidude indicatior in front of them, with ROD unwinding like hell. With all electrics operational inertial systems are very reliable. Can one of the Bus drivers comment if the flight display shows the attitude indicator in the situation they where in and not some garbage error messages?

eswdev

28th May 2011, 09:23

How did they gain 3000 feet at a rate of 7000 feet/minute if they started off in a stall? Is it possible they were trying to climb over the weather? Or that they were in a strong updraft?

JPI33600

28th May 2011, 09:25

jcjeant
Read the BEA document again: it doesn't say that invalid speed condition lasted less than one minute, it says that inconsistency between LH speed display and ISIS speed display lasted less than one minute.
Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less than one minute. (my bold)

We can probably infer that further invalid speed conditions were equally reported on LH panel and on ISIS.

blind pew

28th May 2011, 09:29

Aussie
guess you have never had a whiff of oxygen in cruise at night and seen what effect it has on the eyes.

others
BA 747 - why did they declare a mayday into egcc if they new what they were doing.

Didn't say they put full back pressure on the stick for 30 secs but I have witnessed pilots unintentional inputs when stressed.

Often in sailplanes had guys push right rudder or both when they thought they were not going to stop.

Never witnessed a anyone take the autopilot out in cruise at night to hand fly it - but then again I only worked for three flag carriers.

But then again we had SOPs which said we weren't allowed to fly manual if CWS was available - same with A/T on several types.

Genghis the Engineer

28th May 2011, 09:33

jcjeant
Read the BEA document again: it doesn't say that invalid speed condition lasted less than one minute, it says that inconsistency between LH speed display and ISIS speed display lasted less than one minute.
(my bold)

We can probably infer that further invalid speed conditions were equally reported on LH panel and on ISIS.

We can also probably infer that the crew, having had fluctuating and differing airspeed indications, did not trust anything they saw on any ASI by the end, even if they had settled down.

G

peplum

28th May 2011, 09:34

Could anybody tell me why on a airliner that should have at least 3 sources of speed indicator (pitot tubes, GPS and inertial system), why the crew did not rely on the 2 sources that have been concomitant : GPS or inertial ?

EDLB

28th May 2011, 09:45

We can also probably infer that the crew, having had fluctuating and differing airspeed indications, did not trust anything they saw on any ASI by the end, even if they had settled down.

As a pilot you know you are going to die at night over the ocean in a thunderstrom if you trust no instrument at all. I expect more will to survive from any pilot.

aussiepax

28th May 2011, 09:48

blind pew

No,I only see it during the day in my operating theaters. So what kind of oxygen saturation then are you pilots registering then, in cruise. Why do your companies think this appropriate to normal flying. Why would pilots not insist on some oxygen supplementation normally, or don masks during such an abnormal circumstance.

JPI33600

28th May 2011, 09:50

Genghis
We can also probably infer that the crew, having had fluctuating and differing airspeed indications, did not trust anything they saw on any ASI by the end, even if they had settled down. Sure. So we are back to my very first question: before discussing how they could have detected/fixed the stall condition, I'd like to understand why they didn't apply the unreliable airspeed procedure (fly pitch/thrust) in the very first place, which would probably have prevented the stall condition from developing.

As I read it from the few comments of 'bus drivers here, this seems to be the initial human cause of the issue (just after the technical cause associated with pitots malfunction).

jcjeant

28th May 2011, 09:53

Hi,

Well .. it's come already over 300 posts !
And it's all speculations ... like any speculations .. or debuncking made after leaks in the press
I think I can name the BEA communication as "an official leak"
Just like in the newspapers (fragmented information who can only lead to more speculations) but this time the newspaper name is "BEA Time"

Genghis the Engineer

28th May 2011, 10:00

Genghis
Sure. So we are back to my very first question: before discussing how they could have detected/fixed the stall condition, I'd like to understand why they didn't apply the unreliable airspeed procedure (fly pitch/thrust) in the very first place, which would probably have prevented the stall condition from developing.

As I read it from the few comments of 'bus drivers here, this seems to be the initial human cause of the issue (just after the technical cause associated with pitots malfunction).

That does seem to me to be the single biggest question - these chaps were experienced and current pilots unlikely to make such an elementary error. It seems likely that there is some other factor that we just can't see in the evidence at the moment.

G

OPENDOOR

28th May 2011, 10:24

Three identical pitot tubes icing up uniformly and finally and collectively failing to provide AS information was the route cause of this accident.

Had they been manufactured by different companies they might have had a differential failure rate.

Just a thought.

peplum

28th May 2011, 10:24

What could have bee arrived if the crew would have forgottent to rely on the pitot and would have tried to sustain 400kts ground speed below FL300 using GPS or inertial ?

Please answer.

Hand Solo

28th May 2011, 10:27

@ Blind Pew - Re the BA747 - just because they declared a mayday doesn't mean there was an actual threat to the aircraft present. The circumstances of the incident are now public knowledge. The aircraft was safely flyable with sufficient fuel at all times. There was no danger present, although the incorrect suspicion that there might be led to an abundance of over-caution.

On the subject of the back-stick input, it's well known that people can thrash the controls under extreme stress without realising it. However to maintain that input for a prolonged period is concerning.

Few people will disconnect an autopilot at cruise levels for a jolly, but most of us will have been required to do so at one time or another. The A320 is a far easier aircraft to fly at altitude than a 747 as it exhibits the same behaviour throughout the envelope. I presume the A330 is the same.

spagiola

28th May 2011, 10:32

Make the math ... and the result is not "little less than one minute"

The speeds were invalid because of disagreements between the sources ("incohérence") from 2:10:05 to 2:10:51, which is indeed a little less than one minute.

They then became invalid again at 2:11:40 until 2:12:02+15 -- but, as the report pointedly states, because of IAS falling below 60KT, NOT because of disagreement between the sources.

blind pew

28th May 2011, 10:35

Aussie
we fly at cabin altitude of 8000ft.
the partial pressure of O2 is further decreased by recirculating the air through the cabin.
On long high flights it can result in severe headaches amongst other symptoms.
Anything over eight hours I developed bad ones.
Age paid it's price as well.
Many of our guys used our masks for 10 mins before we started descent on long haul night flights as well as when we were tired on short haul or hung over.
I've also used O2 around the ITCZ.
Once erroneously deviated 100+miles off track (with permission) due to miss reading the wx radar. Putting on the mask helped me to literally see the picture.

The air /O2 quality issue has somewhat been addressed by the dreamliner and O2 scrubbers.

But it goes back to cost and recirculation fans burn less kerosene than bleed air consumption.

blind pew

28th May 2011, 10:50

hand solo
I know there wasn't any threat to the 747 but the crew didn't.
They declared what they thought was a genuine mayday and that there was a serious fault with the fuel system.
The cross feed procedure had been changed by BA to use the jettison pumps.
Although the manuals were correct none of the crew understood the basics of jettison pump feed.
The incident resulted in a change of checklist procedures as well as training.
It's all in the report.

This was a simple system not rocket science.

And the three of them had hours to refresh their knowledge as well as totally valid information.

Don't forget that our american cousins were seriously p*****d off with this fiasco.

My point is the air france boys had the cards stacked against themselves and I sincerely believe with the little that we know so far that it was an accident waiting to happen and but for allah I would end up in the same boat.

henra

28th May 2011, 11:05

henra, I don't think there is anything as Alpha Floor protection in case of A/THR failure.

I was also puzzled about this fact. On the one hand the text says A/THR failure.
I am not sure if this is the same as A/THR disconnect or if it strictly means failure.
On the other hand there seems to be no indication of Alpha_floor activation. But this could also be due to ADR disagree.

JPcont

28th May 2011, 11:10

Somehow, I feel that there is much discussion about the safety of the FBW-systems but not from control theory point of view. From control theory point of view the functionality is more important that the means the functionality is implemented. The same functionality can often be implemented with computers or analog devices. As far as I have understand, computers are often more reliable.

With computers you can implement features that can not be implemented with analog devices. However, the basic questions remains the same. You have to solve at least stability, reliability, controlability and observability problems.

I have a feeling that that the pilot aids are not the core problem but the practices. I don't know if the sales men, who promote the new protections, or technical persons who don't reorganize the potential problems, should be blamed.

When you have deep enough understanding on the control theory, you should understand that every time a inequality constraint is changing the status, the risk level is increased. When there are too many inequality constraints in the system, it becomes practically impossible to analyze it completely.

The common sense says that when system is driven against too many constraints, the control system capabilities are misused. It corresponds the reasons of the financial crisis: “insure” instruments were used as money making instruments.

I feel that every time a control law is driven against “hard” protection constraints, someone has made, at leas a small, mistake in the chain form design to practice. If it is a common practice to solve problems by driven the system against protections, there is something fundamental wrong in the culture.

I feel that every time protection is activated the situation should be studied afterward and practice to avoid the activation of protection should be learned. If it is acceptable to use protections in a normal operation, the safety gains of the protections are destroyed. Most likely the safety is decreased because the skills of the pilot are not gained.

As far as I have understood right, the cause of this accident is pilot error. It is hard to deny it. The real question is: what lead to the errors. We might found out that they acted relatively reasonable...

As a control engineer I feel that would be relatively easy to substitute the pilot in the “normal” conditions. I feel that the pilots are in on board to solve unexpected situations. Humans are better than computers in those conditions. However, human has to learn how to act. If in the training everything goes too smoothly, I have to ask what in hell the pilots do in the cockpit? The problem solvers have to trained to solve problems.

henra

28th May 2011, 11:17

Hi,

IMHO it's sometingh wrong in the BEA communication ....

No nothing wrong with it.
You need to distinguish between the ADR disagree due to the icing which was the event that lastet less than a minute and initiated this accident and the invalid airspeed due to the high AoA which occcured much later and was a consequence of it..

PH-OY-73

28th May 2011, 11:24

Gentlemen, ladies,

Although the airplane was apparently never in an extreme attitude, the pilot somehow did not recognize the stall condition, or the position of the horiz. stabiliser. Could it be overreliance on Airbus' Flt Ctl Systems and mentally 'ruling out' basic indications?

In any case, the following statement, especially its last paragraph, in the Airbus Flight Crew Training Manual (OP-020, Abnormal Attitudes) reflects what I believe is a fundamental problem in the attitude of Airbus, and their design philosophy, and could be a contributing factor to the fate of AF 447.

"It is very unlikely that the aircraft will reach these attitudes, because fly-by-wire provides protection to ensure rapid reaction far in advance. This will minimize the effect and potential for such aerodynamic
upsets.
The effectiveness of fly-by-wire architecture, and the existence of control laws, eliminate the need for upset recovery maneuvers to be trained on protected Airbus aircraft.

peplum

28th May 2011, 11:26

Why did they not rely on the ground speed to regulate their thrust ?

sustaining 400kts ground speed @FL300 or 350kt ground speed @FL200 could have save them.

Why in case of IAS malfunction they do not use the ground speed (GPS AND inertial both provided it) to evaluate their air speed ?

davionics

28th May 2011, 11:27

peplum: The pitot-static system provides Air Data, relative to the medium which the aircraft flies in, unlike the other sources you listed. An analogy; think of a boat on a river - if the river is moving at 30kts and the boat is going against the flow at 30kts, then it's GPS and INS might show 0kts... but the boat would see a flow of 30kts at it's hull.

I've finally caught up on the day's messages, and I'm intrigued and saddened that with such safety-critical data sources (Air Data sensors), there is still little redundancy in design offered. I.e. Are there 3 different air data sensors designed by 3 different companies, based on 3 different sampling principles, and then 3 of each onboard?! Pilots, and computers/software, can only compute and respond effectively (without error) if their senses / sensors can guarantee dependable data.

This could well be a systemic disease inflicting mankind lately, take for example the design of Fukushima and other BWR's around the globe... listen to what ArnieG has to say about that...
The Implications of the Fukushima Accident on the World's Operating Reactors | Fairewinds Associates, Inc (http://www.fairewinds.com/content/implications-fukushima-accident-worlds-operating-reactors)

peplum

28th May 2011, 11:39

We're not on a river but a jet in the atmosphere.

The wind could be evaluated at max +-75kts in this cas. Even if you add or remove 75kts you're always in the flight domain of the plane using my values !

Anyway think one moment. To fly a plane to must evalute the air speed. Because they were high altitude, and the 3 pitot was off, the only indicator effective at this moment was ground speed.
unless you prefer to open the window and reach out to assess !
I'm not Einstein but I hardly imagine none of the 3 pilots try to use this evident method to adjust thurst and sustain a correct FL.

chaz88z

28th May 2011, 11:43

As JCjeant said it, >300 posts over speculation, human-vs-computer battle.

But this accident is like any-other a combination of several factors and their consequences, I'll try to summarize those :

1°/ Pitot failures
- No more valid speed indication
- A/P A/T disconnection (corrective actions taken by crew : "I have controls")
-Switching to alternalte law (Identified by PM "Alternate law")

2°/ Climb to FL380
-The report says that after the initial right bank the pilot performed a corrective action with a left and up S/S deflection.
-Pitch gradually increase over 10°UP. Vertical speed goes to 7000fpm (corrective action : Pitch down)
-Bank values oscillating between 12°right and 10°left. (Corrected by the pilot, but maybe a hint of the flight enveloppe limitation and turbulences)

3°/ First stall warning and pilot corrections
-PF sets TO/GA, and Up-stick force (Seemingly an approach to stall procedure on a non-FBW aircraft : power and initially a small up-stick force as a reflex to maintain constant pitch)
-Consequence of the up-stick force on the A330:
-The pilot fly a G-acceleration, thus constant upward acceleration is commanded as long as the stick is in the 'up' sector
-Auto-trim sets THS up to 13°

4°/ Stall At one point between 02h10'51 and 02h11'40
AoA rises to 16° which is the basic stall AoA at low altitude, at FL380 stall will surely occur at a lower AoA.

5°/ Entering "deep-stall" Between 02h11'40 and 02h12'02 ---> Lasting 22sec only. At a maximum altitude of FL380 the A330 is now completely stalled and descending.
-AoA reaches 40°(Computers switches to 'Abnormal attitude law' (AoA>30°) and auto-trim is disable (Trim wheel is now stuck at 13° up even if it could have been moved by the PF, but with no force-feedback on the stick how to use the trim without QRH/FCOM references?)

6°/ Stall warning 'bugs' begin
-The AoA is so high that Pitot airflow might stall, showing speed below 60kts
-Stall Horn STOPS (IMHO one of the key info that kept the crew in a wrong situation awareness)

7°/ More corrective actions from PF at ~02h12'17
-Pitch down input (correct action to get out of the stall)
-As airfow gets back in the pitots 'speed became valid' and Stall Horn rings again.
(IMHO this is the other key info given to the pilots: the PF brain might have taken it as a logical computer :
Alarm rings ---> Erroneous Action ---> What was my last action? ---> Pitch down input <---CONCLUSION---> Pitch-down input = Error)

As the aircraft is still in a stall with a more than 10.000ft/min rate of descent, the BEA did not communicate on the period between FL350 and FL100 but a major brainstorm/communication or even actions might have taken place in the flight deck.

8°/Approaching FL100
-Less than one minute before impact
-The other pilot takes over (or maybe the captain from behind)
-Only info is 'AoA remained over 35°'
(We do not have any info on the last minute inputs, possibly a desperate maneuver)

I hope this will help picture out the overall situation, so people don't only focus only on one computer or one pilot input.

peplum

28th May 2011, 11:46

- No more valid speed indication

False. IAS is OFF but GS is OK.
Air speed can be sufficiently evaluated from ground speed to adjust thrust and do not stall.

Caygill

28th May 2011, 11:50

You can't make a computer perform tasks with data that it known to be erroneous, it's just a logical impossibility. As such, the design of the system - on paper, before a single line of code was written - clearly defined that in a case where it is unable to do its job, the best hope lies with the pilots. So issue a "stop" command to the relevant module (beyond which nothing other than a full reset can bring it back up again), notify the pilots of the failure and leave the flying to them.Sure you can create models to handle any situation, but the risks are naturally increasing with each missing parameter. It's no fuzzy logic, although that would be a good concept to start with :8

I read many inputs on random newspaper forums, asking why cannot GPS-data be used calculate speed if pitots freeze... Beyond the obvious of not understanding the difference between air speed and ground speed, I came to think about something:

Would it be out of question to create an automation graceful degradation, which:

a) would use a pattern of ground speed vs IAS to judge faulty airspeed readings. Give an advisory to pilots before actually making the call to consider it faulty (less voting of three pitot readings).

b) in case of actually loosing reliable IAS and forced switching to alternate law or what ever mode, would use GPS for displaying pilots an educated guess of airspeed, and would use GPS for calculating altitude and a safe attitude and power setting, which would keep the plane in the air in those conditions. The pilot would then have the option of flying the plane manually or rely on an rude "autopilot" using only pre-calculated values to keep the plane in a safe as possible envelope with data available.

c) use GPS to judge whether the plane is stalling or IAS too far out to be considered reliable (re: no stall warning below 60kts).

chaz88z

28th May 2011, 11:56

False. IAS is OFF but GS is OK.
Air speed can be sufficiently evaluated from ground speed to adjust thrust and do not stall.

Will GS appear on the PFD?
Then they will have to check on the ND or FMS, okay it is just a few inches away but then the aircraft was on full auto and released to full manual the workload must have significantly increase in the first seconds, and one might consider the 7000ft up vertical speed to illustrate the amount of workload and a related lack of visual scanning

peplum

28th May 2011, 11:57

You're right. I'm very surprised to not read in the official media the air speed evaluation from the ground speed. I'm quite sure that it's too complicated to recognize the pilots were too clueless and accustomed to use their computers and to consider this simple tips that could save their lives.

peplum

28th May 2011, 12:01

On A320 it does. GS and TAS.

They were 3 pilots. None of them had this simple idea to read the ground speed. Damn, the wind would be at max 75kts (may be more we don't really care).

Open the window and evalute the wind !
No, just read the ground speed.

You're at FL300, sustain as much you can 400 kts GS
You're closer of FL200, aim 350 kts GS.

Automatic pilots makes intelligent people too stupid when deconnected.

And please indicate air incidence should be considered main indicators.

paull

28th May 2011, 12:02

Genghis,
"these chaps were experienced and current pilots unlikely to make such an elementary error. "

Only one of them made the mistake, the other two did not know what he was doing. PF used up 27'000 feet and PNF then had a go with less than 10'000 feet left. You are there to monitor the other guy but cannot see what he is doing, so you assume he is getting it right, at least to start with? In my book that gives you a single point of failure and that is a bit naughty.

davionics

28th May 2011, 12:02

I grossly over simplified, but sometimes 'simple' provides us the best analogy - fluid mechanics aside. As the last resort option (beyond having desirable sensor redundancy etc), GPS or INS could have been the only, albeit inaccurate substitute for air data available during the reported pitot icing. Can a 'bus pilot tell us what the safe operating airspeed margin 447 might have had at FL370?

Zorin_75

28th May 2011, 12:04

I'm intrigued and saddened that with such safety-critical data sources (Air Data sensors), there is still little redundancy in design offered. I.e. Are there 3 different air data sensors designed by 3 different companies, based on 3 different sampling principles, and then 3 of each onboard?! Pilots, and computers/software, can only compute and respond effectively (without error) if their senses / sensors can guarantee dependable data.
Temporary pitot failure may have been a factor, but it's not a good enough reason in itself for an otherwise fully intact a/c to fall from the sky. They recognized UAS, there's a procedure for it, why didn't they apply it? Or at least common sense? The plane was flying well before the pitots failed, it would very likely have continued to do so if they had maintained pitch and thrust. Instead for reasons yet unclear they performed a manoeuvre leading into a stall. Then they either failed to interpret the situation or didn't / couldn't apply appropriate measures to recover from it. Again for reasons unknown yet.
There's still far too much open questions and to most of them 'pitots' doesn't seem to be a good answer.

peplum

28th May 2011, 12:06

What are you looking for, Vs @FL370 ?

eswdev

28th May 2011, 12:11

chaz88z

Your 2nd item omits to say that there were two stall warnings after the PF corrected the bank to the right. Subsequently the aircraft climbed at a high rate. The high climb rate must mean that the stall warnings were not valid; could they be triggered by invalid airspeed rather than excess angle of attack?

HarryMann

28th May 2011, 12:16

If the pilots mistakenly believed they were in windshear conditions, it might explain why the pitch attitude was around 17.5 degs for most of the time, and why full back stick was used to prevent height loss iaw QRH 1.26.Eeek! - What is this ridiculous fascination with minimising height loss everyone is quoting (modern pilots) as having during cruise ... ???

At 35,000 goddam feet... really... who is dreaming up these latest training schemes ?

busTRE

28th May 2011, 12:16

peplum

28th May 2011, 12:17

I've read the stall alert is invalid when AoA is too high bevcause AIR speed measure cannot be intrepated as valid.

Why did they sustain a such AoA ? Do the plane displays (sufficuently) it on instruments ?

Bus Driver Man

28th May 2011, 12:24

henra

28th May 2011, 12:29

Peplum and others:

You simply cannot use ground speed.

The wind could easily be 150kts or more in any direction ( I don't kow where you get the idea that 75 is a maximum Peplum, it just isn't). So, if you maintain 400lts GS as you suggest you might be doing 250 or 550 or anything in between. i.e. you have no idea. At near to service ceiling the safe speed range can be as little as 30 kts wide and yet you think it is fine to use a method that has a 300 kt (or more range of error). I can only assume you are not professional pilots to have made such a basic error.

Where do you take the 30kts from?
WRT to ground speed the margin is roughly 100kts GS. (~M0,68 - ~M0,86)
The mistake you made is the same one sees over and over again. the 30kts range is IAS. For inertia of the airframe, it's GS that counts. IAS is aerodynamics, Gs is mechanics.
You can't have it both ways, sorry.

GS 400 kts would have been btw much better in any case than GS 110kts (that's what they had roughly). GS should have given them a clue how the thing was plowing through the air. Even if not exact enough for perfect flight, it might have saved the day.

peplum

28th May 2011, 12:29

I do not pretend to be a pro. I'm not. That's not a pilot question. In life, whatever the job you have. When one parameter is vital for you and you don't have it anymore you have to evaluate it.

My thinking is when you do not have anymore reliable IAS, how do you evalute it ? Which clue do you use to evalute it. If not GS, which other do you propose ?

What did source of information they can use to evalute IAS : Ground speed and that's all.

Of course the range of possible speed is narrow at FL350. So, why to pitch-up ?
One wind can be fastet then 75kts, so descend... or praise for it to be less than 75kts but you have to set-up a strategy to replace the automatic pilot and pitot/mach meter did.

Why did they expect climbing to FL380 ? To my knowledge atlimeter was OK. So they should know what they did climbing so high.

Other pilots have reported to live comparable IAS disfunction on airbus and do escape.

Sorry but I do not understand why they do no exploit G.S.

David Horn

28th May 2011, 12:35

Anyway think one moment. To fly a plane to must evalute the air speed. Because they were high altitude, and the 3 pitot was off, the only indicator effective at this moment was ground speed.

No, in this situation pitch attitude and power is the primary reference.

I wonder if this will be the deciding factor for Airbus to implement back-driven sidesticks?

Edit: added "power" to statement above; thought it was obvious.

peplum

28th May 2011, 12:37

I would say both. pitching 0° at 0 kts means nothing.

busTRE

28th May 2011, 12:39

Henra

At the limit of the envelope the margin can be as little as 30kts TAS from Vls to Mmo. MAch and GS have nothing whatsoever to do with it. The aircraft stalled. This is an aerodynamic event. How have you calculated your 'safe' mach numbers because they bear no relation to reality mach .68 could well be below minimum at high level and high weight.

I fail to see what the aircrafts inertia has to do with it. It may have a slight bearing on rate of stall recovery but the important info for stall recovery are aerodynamic. IAS, TAS AoA.

I say agian GS has nothing to do iwth it and only an idiot would use it to handle the aircraft when he has attitude and thrust available to him.

Graybeard

28th May 2011, 12:49

The aerodynamics of the plane is a perfectly good airspeed indicator.

For a given weight and cg, the pitch angle (nose up/down), as shown on the Attitude Indicator, will indicate airspeed. Pitch down, and the plane speeds up; pitch up and the plane slows down. It's there staring at the pilot throughout every flight.

Oh, that happens to be the basic of the Unreliable Airspeed Indicator training.

Of course, some 35 years ago, the FAA began preaching that pitch controls altitude and power controls speed, and too many bought into it, but that's for another thread..

Zorin_75

28th May 2011, 12:50

For inertia of the airframe, it's GS that counts.It counts as soon as you hit the ground. But to keep a plane in the air airspeed is all that matters.

What did source of information they can use to evalute IAS : Ground speed and that's all.No, GS is pretty useless. What would have worked is pitch and thrust.

henra

28th May 2011, 12:53

Henra

At the limit of the envelope the margin can be as little as 30kts TAS from Vls to Mmo. MAch and GS have nothing whatsoever to do with it.

The reference was at FL350 @ ~200t and for the Mach assuming still air to show how wide the difference is regarding TAS.

at FL380 it was probably indeed down to 30kts but going there was not a good idea in the first place. The idea of peplum to go to a lower altitude where the margin is wider and to go to a reasonable GS is better than what happened here, even though not perfect. It is not a good strategy to fly the plane by GS but it could be used to check plausibility of one's own assumptions about what is going on. GS can't be trumped and if GS says 110kts, you get a clear pitcure about what's wrong.

@Zorin_75:
No contradiction:
For flying it's IAS that counts.
Inertia (i.e. Decelleration/accceleration) happens based on TAS. (Rho/2 * V_TAS ^2).

easyflyer

28th May 2011, 12:53

Power + Attitude = Performance, on a C152 or A330.

peplum

28th May 2011, 12:54

No, GS is pretty useless. What would have worked is pitch and thrust.
ok pitch -10 Toga and you'll soon see if that all that counts :D

busTRE

28th May 2011, 12:54

Well done Zorin. Its pitch and power that would save them.

Pitch alone tells you nothing by the way, Graybeard, since a moderate pitch with a high angle of descent=high AoA as in this case.

I hope the non pilots can now accept that GS without air data is just meaningless for aerodynamics, absolutely meaningless.

Graybeard

28th May 2011, 13:05

busTRE:
Pitch alone tells you nothing by the way, Graybeard, since a moderate pitch with a high angle of descent=high AoA as in this case.

A moderate pitch with high angle of descent means not enough power to hold altitude. Use power as needed to control altitude.

This assumes a non-stalled wing, of course, which such events begin with.

davionics

28th May 2011, 13:13

Zorin_75: From an engineering perspective; invalid (faulty) air data from non- design-redundant sensors appear to be the weakest link imho, triggering a cascade of errors thereafter.

Band-aid, extrapolated solutions just don't fly with me. If someone is going to give a pilot or a computer Air Data, then sure as aunt betty make it dependable, fail-safe Air Data. It's really just that simple. Alternatively, a crew of two pilots, and MacGyver might suffice.

spagiola

28th May 2011, 13:26

max_torque

28th May 2011, 13:28

Whilst i can see the argument for pitch & power as overriding targets, as a non pilot, surely there is more to it than that? For example, during the previous hr or so of the flight (at FL350) there must have been an "average" values for pitch, power and GS, that have been clearly demonstrated to "fly" the airframe in a sensible trim.
So surely, in the case of upset, these values would have been a nice place to start trying to aim for, no matter what your AS instruments are saying to you?? Clearly, under no conditions would a groundspeed of 110kts be acceptable (unless you are flying into the MOTHER of all headwinds, which the rest of the flight would have demonstrated to be false??)

The big question, is what parameters and causal factors lead the 3 pilots to incorrectly determine the necessary actions to recover?

Like all things in this world, everything is a compromise, i'm sure we could build an "uncrashable" aircraft, but no one would be able to afford to buy or fly it!

The most important thing, is that if clear and accurate action/response recomendations are forthcoming, that these are precisely implemented.

Unfortunately, there are no absolute answers in risk management, it's a "make the best job you can with the resources availible" problem.

davionics

28th May 2011, 13:37

spagiola: I think that would work (in a brief sensor fault condition), but estimated values degrade with elapsed time and environmental transcients as you say - wouldn't it just be better to be able to depend on reliable air data?

Mach62

28th May 2011, 13:41

Another leak (not verified): http://jacno.com/prov/images/extrait-fdr-cvr.png

See posts #83 and #84 on this page (in french): Forums Aviation Civile • Afficher le sujet - Airbus Rio-Paris : les dessous cachés des enquêtes (http://forum.jacno.com/viewtopic.php?f=2&t=4&start=50)

A THS related incident involving a Falcon 7X and the subsequent release of an EAD http://jacno.com/prov/EASA_EAD_2011-0102-E_1.pdf and the grounding of the world's Falcon 7X fleet.

Are both AF447 and this Falcon 7X sharing some software or hardware components ?

Comments ?
Regards.

Zorin_75

28th May 2011, 13:44

From an engineering perspective; invalid (faulty) air data from non- design-redundant sensors appear to be the weakest link imho, triggering a cascade of errors thereafterDon't get me wrong, I'm all for reliable sensor data, of course.
Still, such a failure shouldn't (and doesn't need to) lead to losing control of an aircraft. Any accident is a chain of events with often many contributing factors. So far, large pieces of the puzzle are still missing.

fourgolds

28th May 2011, 13:46

I am curious as to what caused the initial upset ( with a climb rate in excess of 7000 fpm) according to flights website. The statemet that the Captain briefed the crew about turbulence ahead is a little ambiguous. Did he mean immediately ahead ? or just a reminder that it was forecast on the flight ? That question is relevent ? Altough they did make an initial turn of 12 degrees just prior to the upset. I guess they were avoiding weather .

Also , could there be a link to this and the QF 330 incident where they unexpectantly had an upset ? Cant recall all the details of that incident , apart from unexpected , climb or desent .

syseng68k

28th May 2011, 14:01

davionics, #353

Band-aid, extrapolated solutions just don't fly with me. If someone is
going to give a pilot or a computer Air Data, then sure as aunt betty
make it dependable, fail-safe Air Data. It's really just that simple.

Absolutely. There's no engineering reason why it can't be fixed either.
They have had years to deal with it as well. I know pilots are a hairy
chested breed who don't like to make a fuss and think that they can
handle any situation, but my argument is that they should never be
expected to handle some of them. I think the regulators will need to
have much sharper teeth in future, both to overcome industry inertia
and airline beancounter interests.

Doesn't the A380 have a laser based or alternative air speed sensor
as a option ?...

jcjeant

28th May 2011, 14:05

Hi,

Another graphic chronology events with ACARS included:

Click link
imgur: the simple image sharer (http://imgur.com/Iu3zU)

Caygill

28th May 2011, 14:18

I suggested this on the initial AF447 thread, and didn't get much response, but I don't see why it would not work:

As long as you have a valid IAS, you systematically compare it to GS using GPS and compute wind speed and direction from that. You store this value. If the IAS fails, you use this stored value to correct the GPS-derived GS to get an estimated AS.

Except in the case of severe wind shear, why would this not work?

You could present the estimated AS as a range, with some degree of uncertainty, incorporating previous variations in wind speed, if any, or just an uncertainty factor (perhaps growing over time) to account for possible changes in wind speed.

I've suggested the same. Ok, flying into a weather front - as they did - could mean rapid changes in both direction and speed of winds. Yet having an advisory reading on your display, perhaps showing GS, IAS and their difference side by side in colored numbers could be, I'm imaging, a handy tool when things start to go wrong.

RatherBeFlying

28th May 2011, 14:23

The consensus seems to be an incredulity as to why on Earth the PF held backstick? None of us would ever do that.

Speculation: PF felt the stall warning was triggered by a 10000'/min downdraft -- and just before, he felt he had hit a 7000'/min updraft that he had countered with forward stick. Perhaps PF hung his hat on his windshear/terrain avoidance training.

When in a rapid descent, a low airspeed indicates stall which requires stick forward while increasing airspeed indicates spiral dive which requires wings level and stick back (leaving out the finer details of spiral dive recoveries for sake of brevity).

But here the crew does not have an airspeed worth looking at as it is flopping back and forth.

Recovering from an upset at night in IMC is demanding enough. When you don't have a believable airspeed to distinguish between stall and spiral dive, you have a 50/50 chance of getting it wrong.

In normal weather in a spamcan or glider, you can hear increasing airspeed. Not so easy in a CB.

voyageur9

28th May 2011, 14:33

jcjeant
do you have the spreadsheet, or just the image?

Diversification

28th May 2011, 14:40

"listen to what ArnieG has to say..."
I got that talk in print. To a large part rubbish. Because it is in my own area of specaialist competence it was sad to read. Many statements made are wrong, e.g. that PWR:s dont't have containment venting systems, In Sweden I know of three PWR:s which have venting systems connected to venturi scrubbers.
The problems at Fukoshima seems to have been that their "hydrogen recombiners" needed electrical supply to operate. Electricity as assumed to be available from four sources - batteries, diesel generators, perhaps house turbine operation, and perhaps even the main grid. All had to fail during the same time.
I sincerely hope that most of you have better knowledge in the field of aircrafts and flying.

Regards

KeyPilot

28th May 2011, 14:41

There's an aspect of the BEA report no-one has yet commented on on this thread.

It states: "The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds." [my emphasis]

My questions are:

1. What would be the effect of prolonged application of full roll deflection in a stalled A330, and
2. What might lead the PF to make such input?

takata

28th May 2011, 14:49

Hi,
Another graphic chronology events with ACARS included:
This is a usefull job except for the time stamping of ACARS.
Those messages should not be based on such a precise reception time stamp as it is different from when it was triggered (and in what particular order), but rather by its time stamping from its emission time which is the nearest minute (0210, 0211, 0212...). If displayed like that, it may conduct to a very bad interpretation in relation with real time cockpit events.

jcjeant

28th May 2011, 15:00

Hi,

This is a usefull job except for the time stamping of ACARS.
Those messages should not be based on such a precise reception time stamp as it is different from when it was triggered (and in what particular order), but rather by its time stamping from its emission time which is the nearest minute (0210, 0211, 0212...). If displayed like that, it may conduct to a very bad interpretation in relation with real time cockpit events.
S~
Olivier Of course .. but who know the exact realtime stamp in situ of the ACARS ?

jcjeant
do you have the spreadsheet, or just the image?

Image only

Ashling

28th May 2011, 15:07

RBF

Surely in a spiral dive you would have increasing G if you pulled backstick which you could sense. Can't see the confusion myself, certainly not for 4 min's.

It may well be when all is said and done that we will have to accept that the crew got it wrong, in failing to avoid the weather (if that is what it was) and the Captain in his bunk and in how they dealt with the failure's when they occurred. Not a pleasent thought but there it is. What we need to ask ourselves, each individually, is if it could happen to them could it happen to me. I would like to think that I could have dealt with it, then again I would like to think that 3 trained pilots flying for a major carrier could have dealt with it They didn't. Time for me and all of us to review a few things.

Razoray

28th May 2011, 15:09

This boys and girls is a poser and now you know... When you see the melodrama, they are using it to cover a lack of knowledge, read someone else.

Ok, got it. But you just pulled the same stunt...and you just joined....let's move on...

spagiola

28th May 2011, 15:10

Another leak (not verified): http://jacno.com/prov/images/extrait-fdr-cvr.png

See posts #83 and #84 on this page (in french): Forums Aviation Civile • Afficher le sujet - Airbus Rio-Paris : les dessous cachés des enquêtes

EVERY single post on that site seems to be by the same, vitriolically anti-Airbus poster. Caveat emptor, I'd say.

peplum

28th May 2011, 15:19

Do the inboard weather radar can estimate air speed ?

Garrison

28th May 2011, 15:24

It seems odd that loss of the pitots should cause the whole system to become unworkable. Is there any sort of backup, eg inertial? I know there are three pitots, but if one can be overwhelmed by ice, then all can, and so three are no better than one. And if the FDR knows the pitch attitude, the angle of attack, and the rate of descent, why don't the pilots? The airplane seems to have had plenty of forward speed: 10,000 fpm vertical = 99 knots, with a flight path angle of -25 degrees (40 aoa - 15 pitch) suggests a TAS of 99/sin(25) or 234 kt (is this right? -- somebody help me out here) and it was responsive to roll inputs. I completely understand and sympathize with pilot confusion and mental paralysis, having experienced it myself, but it seems as if there are big issues here of information presentation and human/system interface, notably the counterintuitive behavior of the stall warning. We know, and the FDR seems to have known, that the airplane was stalled; why wasn't there a nice firm female voice telling the crew so the whole time?

Microburst2002

28th May 2011, 15:26

no, it cannot.

And i don't know if they had any GPS, but IAS and GS at that FL are so different that it would be useless.

takata

28th May 2011, 15:28

Of course .. but who know the exact realtime stamp in situ of the ACARS ?
You don't know the "exact" realtime, but the "nearest minute". Quite simply, when you don't know something (a precise factor), you don't make it up. In this case, you can only list those ACARS, in no particular order, by minute with what information the CMC provided (0210, 0211, 0212..) and assume the time range boundaries for each to be sent.

Hence, you can't have a direct relation with any particular "second" of the real time scale :
- if an ACARS was CMC stamped at 0210 and stamp recieved at 0210:26, all you know is that it could have been triggered between 0209:31 (the nearest minute) and 0210:20 (as you will allow about 6 seconds for processing). If the same was recieved at 0211:31, it would be meaningless to look outside the 0209:31-0210:30 window in order to understand what caused it (in this case, there is certainly no relation with events past 0210:31 even if it was recieved one minute later).

Bienville

28th May 2011, 15:29

EVERY single post on that site seems to be by the same, vitriolically anti-Airbus poster. Caveat emptor, I'd say. And isn't it interesting that these "vitriolically anti-Airbus posters" always manage to have 'sources' in the investigation that get 'leaks' that -just happen- damn Airbus... but later when the real facts come out, the 'leak' was poppycock.

It's almost as if they are sitting in their mom's basement making stuff up.... not that we'd ever see anyone do THAT on the internet. ;)

promani

28th May 2011, 15:30

'At 1 h 55, the Captain woke the second co-pilot and said "… he’s going to take my place" Who was he referring to? The DailyTelegraph reports ....'according to flight recorder data, the younger of the two men, Pierre-Cédric Bonin, 32, angled the jet's nose higher'. David Robert, 37 was the other FO, and he was licensed to replace the captain. So if M. Bonin was nominated by captain Dubois to take over, then why as it appears he was not licensed to replace the captain, as per the BEA Interim report.

keesje

28th May 2011, 15:59

I did not read the previous hundreds of post, but it seems the crew had an entirely different perception of what was happening during the last minutes.

It seems if they had a better awareness they could "easily" have regained control, right? (pushing the stick)

I'm admit to be lazy here , but isn't there any speed measurement backup procedure if e.g. the pitots block/freeze? (e.g. GPS, Iphone ? ) It seems they had little time but some minutes..

The 330 in better days..
JetPhotos.Net Photo » F-GZCP (CN: 660) Air France Airbus A330-203 by Aurélien TRANCHET (http://www.jetphotos.net/viewphoto.php?id=6056474)

mitrosft

28th May 2011, 16:03

peplum

We're not on a river but a jet in the atmosphere.

The wind could be evaluated at max +-75kts in this cas. Even if you add or remove 75kts you're always in the flight domain of the plane using my values !

Anyway think one moment. To fly a plane to must evalute the air speed. Because they were high altitude, and the 3 pitot was off, the only indicator effective at this moment was ground speed.
unless you prefer to open the window and reach out to assess !
I'm not Einstein but I hardly imagine none of the 3 pilots try to use this evident method to adjust thurst and sustain a correct FL

This was exactly my post in 2nd thread. Although for actual flying you do need True Air Speed which is the speed of aircraft relative to given part of the atmosphere, but inertial navigation system should give a very good clue to onboard computer by telling it:

- Hey HAL your air speed dropped from 275knots to 60 knots WITHOUT any decceleration!

-So disregard your speed change and keep the current flying parameters - thrust and pitch. Until deceleration/acceleration tells it that speed changed.

And then give pilots info about unrelaible airspeed.

OPENDOOR

28th May 2011, 16:03

Apologies to anyone with a pilot’s licence or knowledge of aerodynamics.

To everybody else on this thread please listen;

Ground speed is only relevant to an aircraft when you come into contact with the ground (or want to know at what time you will arrive at your destination)

Air is a fluid medium. Whilst airborne air speed is the key to staying there.

When assessing student pilots grasp of this concept I used to ask them a simple question; The wind is 270 degrees at 20 kts and I release a helium filled toy balloon, where will it be in one hour?

During instrument training the mantra is “believe your instruments but keep the scan going” in other words; don’t fixate on one, the primary instruments will tell you everything you need to know. Do not believe your senses, spatial disorientation will kill you.

One other thing I used to teach was APT (Attitude Power Trim)

takata

28th May 2011, 16:03

Hi spagiola,
EVERY single post on that site seems to be by the same, vitriolically anti-Airbus poster. Caveat emptor, I'd say.
Well... look at this url for this pic, the same posted by jcjeant: http://jacno.com/prov/images/extrait-fdr-cvr.png
jacno.com = Norbert Jacquet.
If one really knows who is this guy, the vitriolically anti-Airbus is obviously an understatement. It looks like he's got few fans around, including here (jcjeant,...), that are pursuing the very same crusade than him by always relaying all his "very informatives and unbiased" positions.
Call them trolls, whatever, but be sure that this won't stop any time soon.

deadheader

28th May 2011, 16:05

G'day all,

Very fascinating discussion going on here guys [and gals], well done.

At this stage we are obviously missing some vital clues but I would like to pose a couple of questions if I may:

1> Given the data released thus far can we be absolutely certain of complete system and airframe integrity up to impact?

2> Do we know without doubt there was no degradation of other instrumentation including altimeter & AI?

3> Are we in a position yet to completely rule out external factors including extremely volatile air masses?

Cheers

glad rag

28th May 2011, 16:06

Also , could there be a link to this and the QF 330 incident

Not according to those in the know.

fantom

28th May 2011, 16:08

K.I.S.S.

Why can't it just be simple? All these technical issues are very interesting but are you drilling too deep? I'm not argueing for/against the AB philosophy (for which I am the No 1 supporter; I just love the 320/330), only trying to come to terms with what actually happened.

They lost the pitots and, therefore, airspeed tapes. They had not experienced this before (I have never had a go at this at high level in the sim or the A/c). The PF chose to accept he was overspeeding and pulled the nose up. The auto-trim responded and wound in the nose-up trim. That's what it does. PF is now three minutes from crashing and the captain (probably wisely) didn't exchange seats with either of them (who knows what the turb was at the time?).

Lots of NU trim, at night, no airspeed tapes and three minutes to go.

Would you have done better?

Having spent years watching crews in the sim sorting out problems and noting the time it has taken them, three and a half minutes is not a lot.

PENKO

28th May 2011, 16:10

Come on guys, for all we know they DID check the GPS/inertial ground speed. The report just does not tell us anything of the sort, just as it does not tell us anything else other than some stuff that does not make any sense at all. So please don't say: why did they not do this or that. We just don't know yet.

Of course a lot of scenarios spring to mind, but none can be verified.
Take for example the 16,5 degree pitch up that someone suggested might be a windshear avoidance reaction. Well, maybe. But you would expect TOGA to be applied in such a situation, which did not happen untill much much later! So much for the windshear scenario.

Did the PF think he was overspeeding, hence the initial pull up? Maybe. But he did not close the thrust levers untill 3 minutes after this pitch up.

So no matter what scenario you (or I) come up with, it does not make ANY sense. We are not given crucial information.

Anyway, to me, just as puzzling is the weather these guys were in and it surprises me there is no more discussion about it. There must have been a lot of water floating around at FL350 to cause the pitots to block. I have never flow commercially in those regions so I can't talk from experience about this. So what I'm asking is, is it known to have icing at those altitudes without entering a CB? Is it common? Is it possible?

blind pew

28th May 2011, 16:18

Ashling
I believe they had sensory overload and made an incorrect assessment.

I concur whole heartedly with your post.

Unfortunately many will bury their heads in the sand and say it can't happen to me.

What many of you will not have done is to be locked into a decompression chamber and be starved of oxygen as was compulsory in my training. We had to sign a legal waver and had a doctor and medic in the tube with us. The exercises that we performed were to demonstrate our mental degradation at altitude leading to unconsciousness.
Not posing but just some training is more comprehensive than others.

I recently did a very well briefed SIV paragliding emergency course nr Annecy.
During a relatively extreme maneuver (high G) I put it the wrong input although I had 2 way com and was fortunate that I didn't have to throw my reserve.

In my younger days I was known as a bit of a hot shot - I now accept that I am an old man and make lots of mistakes.

Fortunately my last company look after me extremely well and although I still have a valid atpl I haven't needed to work for more than a decade.

I am just happy that I don't have to fly 12 hour night flights through the ITCZ anymore.

grizzled

28th May 2011, 16:21

bienville...

You found this site and thread and leapt onto it like a young tiger -- a young tiger who hasn't yet learned most of life's lessons, including respect for other tigers. In one of your first posts you insulted a very respected and long-term ppruner who has more wisdom and experience in her little finger than you seem to have in your whole being.

Despite your screams of pilot error, there is nowhere near enough info (publicly) available yet to support any of your assertions. Your simplistic view of what went on up front on that horrid night shows you have little kowledge (or concern) about how the accident chain works in real life.

You yell at ppruners who have been here for years -- and discussing AF447 for years -- presuming to instruct them in how to behave and how to identify trolls.

Saddest thing, though you have been here less than 24 hours, you have succeeded in bringing the level of this thread down dramatically.

JT? You out there?....

Razoray

28th May 2011, 16:31

Saddest thing, though you have been here less than 24 hours, you have succeeded in bringing the level of this thread down as fast as the doomed aircraft itself.

Watch out you are being a bit melodramatic! :}
Well said!

Caygill

28th May 2011, 16:32

Out of my league, but could the assumed loss of situational awareness been due to belief of a non-existing wind sheer pulling the plane first up and then down?

I mean, purely from psychological point of view, they just entered a weather front, then loose speed indication and for what ever reason the plane is first rapidly gaining altitude only to loose it soon after. Could this be part of the scenario, making the believed wrong calls a bit easier to comprehend?

augustusjeremyreborn

28th May 2011, 16:35

It went into the deep stall too easily. Should the cause rest only on the THS trim and/or the PF's pitch-up inputs ?

Sorry if I seem rather intuitive than technical...

Graybeard

28th May 2011, 16:38

Well said.

KeyPilot

28th May 2011, 16:40

Many posts discuss the continuous back stick, but nobody replied to my earlier thread re the sustained (30s) full deflection roll input.

I find this very significant - but puzzling - for a number of reasons:

1. I can only suppose that it was in response to an opposite bank, caused by turbulence => the PF was following the AI in roll; why not also in pitch?

2. 30s is an age to hold in a roll demand - an absolute age. If the aircraft wasn't responding (which one supposes it can't have been) then this would to most of us must again re-inforce the conclusion of stalled flight and certainly eliminate a high speed dive.

To me this can only point to extreme disorientation/sensory deception and refusal to believe the instruments. As has been noted before, a/c have been lost due to e.g. a single AH failure; the level of failure here was more serious, was in IMC at night...

techgeek

28th May 2011, 16:44

I am a pilot and a software engineer. Back in April I posted about a scenario that turns out to be quite similar to what the FDR and CVR describe. In that post I suggested that the pilots would have applied TOGA and full nose up trim. I think it is eminently reasonable, given the pilots' procedures training, practiced in the sim, and their confidence in the FBW system, that the pilots applied nose up control inputs and full power. Don't blame the pilots!

I believe the fundamental cause was that the computers flying the plane used invalid air data inputs (altitude and airspeed) with pilot control inputs that were based on the assumption that the computers had valid air data inputs (altitude and airspeed). I believe the FBW was not designed or tested against this particular set of inputs. That is based on my software engineering expertise and not so much what I know about flying.

PENKO

28th May 2011, 16:48

Techgeek, what scenario would that be at FL350? No pilot knows of a scnenario where you would pull up violently (7000 feet per minute) at FL350. Mind you, without TOGA! That came much later, with the second stall.

GarageYears

28th May 2011, 16:58

I believe the fundamental cause was that the computers flying the plane used invalid air data inputs (altitude and airspeed) with pilot control inputs that were based on the assumption that the computers had valid air data inputs (altitude and airspeed). I believe the FBW was not designed or tested against this particular set of inputs. That is based on my software engineering expertise and not so much what I know about flying.

Nope. The AP and AT disconnected exactly as designed and the PF reported "I have the plane".... at this point the aircraft went where the human pointed it. It was pointed up (and left I believe, in response to a right roll). The computers at this point applied the design protections (where possible) based on Alt Law being in effect, but did NOT control the aircraft in any rational sense of the word - that was the bloke moving the joystick around. Unfortunately the human reaction does not seem logical to (most) pilots here and the aircraft ended up in a pretty bad attitude. (Nose high, AoA very out of shape, and minimal airspeed).

Why is this so hard to understand? :ugh:

bearfoil

28th May 2011, 17:02

"...Many posts discuss the continuous back stick..."

Please show where in the BEA report this is stated.......

"Stick" is a misnomer, 'mainly'. The Sidestick has its own character, and inputs communicate with the computer, not the a/c. It is a discussion, not an assumption.

Philosophy and mechanicals are different words, and in their muddying, much distraction.....

One Outsider

28th May 2011, 17:05

Saddest thing, though you have been here less than 24 hours, you have succeeded in bringing the level of this thread down dramatically.It has been a team effort.

grizzled

28th May 2011, 17:20

One Outsider

I grant you that :)

MountainWest

28th May 2011, 17:37

Feynman, the Nobel Prize winning quantum mechanics guru, wrote about a number of subjects besides physics. He was asked why some students had such difficulty learning to spell certain words. Feynman said the problem wasn't the student, but that the word was not spelled correctly.
Maybe that applies here. If competent, highly trained professionals have difficulty sorting out an already confusing situation in a short period of time, maybe the system is the problem.
Designers need to rethink the interfaces with the pilots, including the complexity of the different levels of degradation. Software engineers need to have a bit less confidence in their ability to produce an infallible product. Time for a major rethink all around, IMHO.

deSitter

28th May 2011, 17:43

Well my animus for software "engineering" is hereby exhibited - all the fancy laws and protection modes had the precise effect of sending 228 people to the bottom because they dealt with meaningless abstractions, not a real world problem.

techgeek

28th May 2011, 17:46

There was indication to the pilots of unreliable airspeed information.

techgeek

28th May 2011, 17:53

deSitter,

That's a pretty harsh indictment of a lot of good people. People are not 100% perfect at flying planes or designing and writing software. Most pilots and software engineers are very committed to continuous improvement in our respective professions. In the case of AF447, great care needs to be given to the point of intersection of these two disciplines precisely because, as you point out, errors or omissions (whether piloting or programming) can lead to people dying.

JPI33600

28th May 2011, 18:03

KATLPAX

28th May 2011, 18:06

grizzled, thanks well said.

Zorin_75

28th May 2011, 18:07

all the fancy laws and protection modes had the precise effect of sending 228 people to the bottom
Again, I think we're still missing too large pieces of the puzzle to tell what really happened. However, from the precious few bits of information that we do have, what makes you come to that conclusion?

engfireleft

28th May 2011, 18:11

Just to try to sort out this man-machine-interface stuff, can we imagine the very same initial event in a more conventional airplane, say, a B757? In cruise at night, George is in control, and all of a sudden all airspeeds go wild and George gives up. What indications are available on the panel, and what is the PF supposed to do?

Attitude + Power = Performance

It is basic stuff that sometimes tends to get obscured in all the magic. It is also the foundation under which the "Unreliable Speed Indication" drill and checklist were written.

JD-EE

28th May 2011, 18:12

Bienville, you are correct. I am not a pilot. I simply read.

"From 2 h 10 min 05 , the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS)."

I read that as the pitots froze up and the stall warning happened. I am not reading the "left nose-up" as being a violent movement such as would stall the plane. I am also reading this as the aircraft presuming 60kts is an obvious stall so let's warn the pilot he's about to stall. (There being no real unique stall warning.) That's the moment the fit hit the shan.

Now, what sequence do you see happening there? It is worded a little ambiguously. But it does seem to say the stall warning was coincident with the abrupt reduction in indicated air speed. And I take it as dead wrong. You cannot stop an aircraft that rapidly. (I read it as "seconds or less" not "tens of seconds" for the "sharp fall" from 275 to 60.

I certainly do not read a left-up control stick movement such as to the left around the storm (context, remember) as being the precipitating event to a real stall with no drop in air speed followed measurable time later by the "sharp fall".

If I am wrong, please clarify the quoted paragraph as you read it.

Clandestino

28th May 2011, 18:14

Period between 0200 and 0600 is called "window of circadian low" for a few very good reasons.

Relevant time zone was UTC+2.

cirr737

28th May 2011, 18:17

I switched onto the big bus just some weeks ago, so I decided to shut up until now... but how some people here speculate on things like the sidestick commands reversing or protections going crazy, I just want to add one thing: Ockhams knife - the most simple solution is the right solution - for some reason somebody just screwed up.

Probable Cause:
Unreliable airspeed leading to the PF reacting to a stall warning with a prologend nose-up command several times, aggrevating the stall.

Contributing Factors:
(1) Lack of training
(2) Man-Machine Interface
(3) Sidesticks not linked -> insufficient monitoring
(4) Icing of the pitots
(5) Fatigue
---- or ----
(6) Somebody beeing plain stupid (reacting to a stall warning with a pitch up is plain stupid) and shouldn't have been let near a cockpit

Just my two cents....

JD-EE

28th May 2011, 18:20

Bienville, to address the response to the stall I very drily note you are correct. The correct response to a real stall is drop the nose (any way you can) and gain speed. Why did the Continental pilot die with a recorded 150# pull on the stick as his plane stalled into the ground? Why have many other pilots responded to the stall warning with a pull up and goose the engines move? Is this because the stall warning is taught as "the plane cannot stall, this is a warning it might (contradictory here but a paraphrase of what I've read here) stall so pull up and push throttles forward some to compensate."

As I read messages here, on this thread, there is no real "you are now stalled" warning for the A330-200.

So as I see it, based on messages here, the pilots reacted to training and pulled up. A slight bit should have sufficed. It didn't work. So from there it turned to poo rapidly.

And if I had to involve a pilot error in the picture that is the moment. They were not thinking when the stall warning happened or THEY would have seen it was spurious. (IMAO the computer should have seen it was spurious.)

edit: (I must say I am impressed by your persistence in your claim that the first stall warning indicated a real stall. It stalled from around 38500' when the airspeed really did get too low for that altitude. The first warning was, as I indicated, purely spurious. If not howinheck did the plane slow down fast enough to enter a real stall? No indication of such a deceleration is made.)

edit2: I note that the 2:10:16 interval notes the pilot flying made a nose down stick movement. So the initial reaction was correct.

Zorin_75

28th May 2011, 18:23

Just to try to sort out this man-machine-interface stuff, can we imagine the very same initial event in a more conventional airplane, say, a B757? In cruise at night, George is in control, and all of a sudden all airspeeds go wild and George gives up. What indications are available on the panel, and what is the PF supposed to do? 1. Check the pitch attitude and thrust.
2. If pitch attitude or thrust is not normal for phase of flight:
Autopilot disengage switch . . . . . . . . . . .Push
Autothrottle disconnect switch . . . . .. . . .Push
F/D switches (both) . . . . . . . . . . . . . . . OFF
Establish normal pitch attitude and thrust setting for phase of flight.

lateott

28th May 2011, 18:29

JD-EE wrote:
...the stall warning was coincident with the abrupt reduction in indicated air speed. And I take it as dead wrong. You cannot stop an aircraft that rapidly. (I read it as "seconds or less" not "tens of seconds" for the "sharp fall" from 275 to 60.

I certainly do not read a left-up control stick movement such as to the left around the storm (context, remember) as being the precipitating event to a real stall with no drop in air speed followed measurable time later by the "sharp fall".

You are absolutely right. The first stall warning was false. The flight dynamics were fine (though I wonder why the computer caused the roll that had to be corrected).

If there was a first false stall warning, would it cause the pilots to question subsequent stall warnings?

lateott

28th May 2011, 18:34

JD-EE is right on. There was no stall initially, just a false stall warning due to a completely impossible "loss" of airspeed.

The stall was created by the PFs reaction to what was not a stall. The computer made it unrecoverable by trimming full nose up.

takata

28th May 2011, 18:39

Hi bear,
"...Many posts discuss the continuous back stick..."
Please show where in the BEA report this is stated.......0210:05...The airplane began to roll to the right and the PF made a left nose-up input.
0210:51...The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs...The PF continued to make nose-up inputs. The airplane’s altitude reached its maximum of about 38,000 ft...
0211:40...The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
[French: 0211:40...Le PF exerce une action sur le manche en butée à gauche et à cabrer, qui dure environ 30 secondes.]
"en butée à gauche et à cabrer"= full deflection, stick left and nose-up (during 30 seconds).

Stick" is a misnomer, 'mainly'. The Sidestick has its own character, and inputs communicate with the computer, not the a/c. It is a discussion, not an assumption.
Real stick imputs chanels are recorded by the DFDR independently of the "computer" imputs. It is how one can see that both pilots are possibly giving "conflicting" imputs, whatever the result is on the "computer" and control surface orders.

ihg

28th May 2011, 18:42

Just a question as I could'nt find any reliable information about it.

What sensors do exactly trigger the stall warning? To my knowledge stall warning depends primarily on AOA sensors (taking into account slats/flaps settings)

Or is any other data also processed by the stall warning (air speed?)?

Assuming that the stall warning primarily depends on AOA sensors, and given that you have no/confusing/unreliable/disagreeing air speed data, why not fully trust or prioritize "stall warning" over all other warnings like potential overspeed warnings?

I mean that stall warning would then be based on sensors, which you still could have faith in , whereas overspeed warning would be based on sensor, which obviously show problems. Problems, which brought you into that situation...so why trust any warning coming from them?

Or do I miss something here?

all the fancy laws and protection modes had the precise effect of sending 228 people to the bottom because they dealt with meaningless abstractions, not a real world problem. Yeah,sure, all that fancy laws and protections left the pilot no other choice but pulling on that stick until the bitter end. :hmm:.
I followed your earlier 'elaborations' about software engineering with some sympathy as I partly can support your 'findings' from my own experience. But given your last post here, you just seem to be another one trying to adjust reality to your own 'agenda' with a given result of the 'blame game' from the very start.

cirr737

28th May 2011, 18:44

@lateott

No, it was genuine - The stall warning is based only on AoA which was valid (except later when the speed dropped below 60kts)

>> The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. <<

With a nose up input at this flightlevel with a heavy A/C you are approaching the critical AoA really quick. And with the roll the load-factor increased leading to reaching the critical AoA even faster

JPI33600

28th May 2011, 18:49

engfireleft and Zorin_75, thanks for your answers:
Attitude + Power = Performance

It is basic stuff that sometimes tends to get obscured in all the magic. It is also the foundation under which the "Unreliable Speed Indication" drill and checklist were written.1. Check the pitch attitude and thrust.
2. If pitch attitude or thrust is not normal for phase of flight:
Autopilot disengage switch . . . . . . . . . . .Push
Autothrottle disconnect switch . . . . .. . . .Push
F/D switches (both) . . . . . . . . . . . . . . . OFF
Establish normal pitch attitude and thrust setting for phase of flight.Now, for those questioning the Airbus MMI, how is the information different on the 'bus panel? Attitude and engines N1 are available as well, so what is this nonsense about the A330 MMI having prevented the pilot(s) from correctly reacting to UAS condition?

JD-EE

28th May 2011, 18:52

henra one thing I really learned tonight is that people just make stuff up.

Please excuse me for a moment while I stop choking on laughter.

There that's better. Now it seems to be that you made up the fact that the plane stalled at the time of the first stall warning without carefully reading the paragraph that defined it. You have a preconceived notion and are driving it into the ground with impressive arrogance.

And to me it looks like you "just make stuff up" to support your notion. You certainly are offering no evidence that the plane COULD have stalled at the time you indicate. What slowed it down far enough? (I will admit that the English in the report could be clarified a little, particularly the paragraph titles. I suspect it's a stylized phrasing for their report purposes. The "From 2 h 10 min 05" indicates "data from" that time shows the following information.)

cxhk

28th May 2011, 18:53

takata, have you ever flown an Airbus ? Have you ever trained for type rating on either 320, 330, 340 or 380 ? I will tell you a ghastly secret : using manual pitch trim is one of the very first things one has to unlearn in order to be accepted as a candidate for type rating. After which, during all operational flight hours, and during every simulator training and check, it is verboten to touch that wheel.

CPT : A330/340 experience -> 1700hrs (plus all hours on A320 not mentioned)
F/O 1 : A320/330/340 experience -> 6500hrs
F/O 2 : A320/330/340 experience -> 2900hrs

It would seem obvious that touching that verboten wheel would have perhaps been useful. But the pilots here had never touched it, even in benign conditions, for a total of more than 10000 hours...http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/boohoo.gif

Svarin, I have no idea which airline trained you, but during my initial A330 training, I clearly recall using the manual pitch trim in direct law. This is to expose the pilot in manual pitch trim and allow us to get a sense of how sensitive the pitch trim really is (and it is bloody sensitive). We fly an approach in direct law with manual pitch trim only, as part of the initial type training / exposure to the airbus flight control law, although this is not part of the regulatory requirements, it is still good to see and very good exposure.

Also on many occasion during our simulator training,our simulator instructor had told us on many occasion that when we are in the coffin corner, and if we had a approach to stall situation, with TOGA thrust being auto apply at Alpha Floor, and with THS being full trim, we might not have enough elevator authority to counter the pitch up by TOGA thrust. Therefore a small amount of forward push of the THS might be required to help with the nose pitch down for the stall recovery, 99% of the time we do not need this, but we were told it is available and do use the THS if needed.

Just my two cents!

bratschewurst

28th May 2011, 18:53

What's not clear from the report is why the PF made any stick inputs at all. My understanding is that, even in alternate law, the computers maintain the pitch and roll attitudes previously commanded until the stick is moved, so presumably the aircraft would have continued straight and level, assuming that was the case when the a/p disengaged.

"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input."

Would the flight control system countered the roll without the PF inputting left nose-up? And what led him to think that he should pitch up at all? If (as reported) he was flying from the right seat, the airspeed he was seeing was not recorded on the FDR, so perhaps there's insufficient information to fully judge what he was responding to.

But it does appear, if my understanding of the Airbus FBW system (gleaned mostly from these threads) is correct, that the aircraft would have continued in straight and level (and unstalled) flight absent the left nose-up input by the PF.

pax2908

28th May 2011, 18:56

Sorry for the silly questions: in ALT, the sidestick controls load factor demand, correct? Once the a/c is stalled, that load factor demand cannot be met. In fact, g would have been <1 at some point. What happens then if the sidestick is in its neutral position? In particular, would the autotrim be active?

ACLS65

28th May 2011, 19:02

The post volume is definitely up since Friday's release, but I don't know that we can say the same for the post quality. We were all hoping for "the answer" to be released on Friday, and I think a lot of people, especially some of the general media seem to feel it was, and that the answer was pilot error.

What we got from the BEA was basically a condensed version of what happened, and it leaves with a pilot taking what appears to be an unexplained action, 30s of pitch up.

Coming from a technical and software background (machinbird and others can probably tell from where) one might think I would be quick to jump on the pilot error bandwagon, but I am not.

If we look at this from the standpoint of Input --> Decision --> Output we have, I feel, only partial insight to what the inputs to the pilots were, we don't know, from what was given so far, what the decision making process was, and we have at least some of the outputs, the pitch, roll, throttle commands but not a real understanding as to why those choices were made when they were made.

Hopefully when a more complete release of the CVR and DFDR information is made we will gain greater insight as to the decision making process and "why" of the pilot actions. I find it hard to believe that if they appear counter intuitive that we are not missing parts of the picture either from the brief release, or limitations to what data is collected in the complete record.

These pilots had a very vested interest in solving the problem they were presented, I strongly suspect there was a lot more discussion and information than we are currently being given. Though the BEA may have been wanting to help stem the amount of leaked information, they may have added to the amount of misinterpretation, or rushed judgement.

I also hope the moderators will ensure that several of our new posters who share a common viewpoint do not originate from a single IP address.

JD-EE

28th May 2011, 19:14

Caygil asked: "Would it be out of question to create an automation graceful degradation, which:.."

There is a patent filed, since the accident, on just this idea.

The more I think about it the more I suspect that the plane could fly perfectly well using only GPS and inertial data if it's looking to maintain altitude, attitude, and speed. Abnormal conditions would be indicated by the precursor conditions to either stall or mach buffet. Actual stall would be indicated by altitude loss. So for modest periods of time the plane could probably do very well on such data as it has. I'm not sure retrofitting this "learning" software into the ancient (in computer years) computers aboard an A330. But it certainly could be incorporated into new designs.

ihg

28th May 2011, 19:18

I am also reading this as the aircraft presuming 60kts is an obvious stall so let's warn the pilot he's about to stall. (There being no real unique stall warning.) That's the moment the fit hit the shan. Well, I would be careful with such conclusions. I asked that question before, but to my knowledge stall warning is based on AOA sensor, not air speed. And crusing at that altitude you dont need anything close to "stop an aircraft" to approach stall, you only need to lose a "few kts", which could well be the result of even only a moderate pull up maneuver.
So for me there is no reason to doubt that even the first stall warnings were correct.

Is this because the stall warning is taught as "the plane cannot stall, this is a warning it might (contradictory here but a paraphrase of what I've read here) stall so pull up and push throttles forward some to compensate."...So as I see it, based on messages here, the pilots reacted to training and pulled up. :bored:...pull up? Excuse me. I have no idea where you get that from,,,,but you will hardly find anyone in the world proposing that as 'stall procedures', except those with suicidal tendencies...

HazelNuts39

28th May 2011, 19:21

If I am misreading some recent posts, I apologize, but there seems to be some confusion about stall warning and airspeed. The sudden drop in indicated airspeed was due to ice particles blocking the pitots, not due to a real speed reduction. Stall warning begins when the AoA exceeds approx. 4 degrees, and that threshold was exceeded at several times. AoA reached 16 degrees at 38000 ft, indicating that the airplane was definitely stalled at that point.

Stall warning, followed a few seconds later by uncommanded left/right rolling motions probably accompanied by heavy buffet is usually accepted as an indication of "you are now stalled".

Khashoggi

28th May 2011, 19:24

Until a fault tolerant method is developed for obtaining airdata, I hope UAS drills become far more comprehensive in the sim. For three rated pilots to miss the recovery is shocking, assuming BEA isn't leaving out some important tidbits.

Oh, and patch the bugs in the stall warning system for low airspeeds and/or AoA... No doubt that design "feature" should be reclassified as a bug.

Lastly, the man machine interface really needs some review regarding sidestick, thrust lever, and trim positions. When you are 3 minutes from doom you should be given enough information as quickly and comprehendible as possible to take over from Otto when he can't figure it out.

RatherBeFlying

28th May 2011, 19:30

Surely in a spiral dive you would have increasing G if you pulled backstick which you could sense. Can't see the confusion myself, certainly not for 4 min's.Certainly one would think so.

In this case we see that Attitude+Power was not obtaining the Performance one would normally expect.

The crew seem not to have realised they were in the stall regime while all us of in our armchairs are at a loss to understand why they did not.

I have seen somebody in a steam gauge sim with white on black AH invert the ac at 16000' and fail to realise what he had done until after he "hit" the ground. Fixation can take over, and deafen you to the guy yelling "roll left" directly in your right ear.

Here it seems the entire crew were aware they were on the way down without knowing why or anybody offering any ideas on how to change the situation for the better.

foster23

28th May 2011, 19:32

many thanks for link on pitch and AOA. as a SLF myself i have followed the AF447 thread from the beginning on PPRUNE. may i ask what is TOGA and the ISIS display. thanks:ok:

mojodaso

28th May 2011, 19:36

"But it does appear, if my understanding of the Airbus FBW system (gleaned mostly from these threads) is correct, that the aircraft would have continued in straight and level (and unstalled) flight absent the left nose-up input by the PF."

Great question, I trust a knowledgeble poster will answer for us.

Thanks in advance

OPENDOOR

28th May 2011, 19:37

Here it seems the entire crew were aware they were on the way down without knowing why or anybody offering any ideas on how to change the situation for the better.

And that, in a nutshell, is what needs explaining.:sad:

JD-EE

28th May 2011, 19:49

OPENDOOR, I figure good sense disagrees with your rather broad statement. The inertial system can tell if the plane has actually decelerated or accelerated by over 200 kts or even 50kts and the mother of all tail winds overtook the plane. So there is a valid software check on the stall warning.

Furthermore, AI seems to think there is enough information in the inertial and GPS systems to keep the plane flying while the pitots recover. The plane has a tremendous amount of inertia. So one minute or less of simple pitch and altitude with comparison between inertial/GPS data on ground speed can diagnose whether they are in a large wind or not. If they are in a savage tail wind they will cover more ground than they should for the past ground speed. The difference is the speed of the tail wind. The same fits for any other strong wind. If you are not deviating from the previous course with no control changes then your airspeed cannot have changed.

It appears on a closer look that my naive question from a couple years ago has an even better answer than I'd thought at the time. It may give a bumpy ride for a couple minutes. But it will keep the plane going very nicely. It can tell you if you did hit a wind, what you need to do to correct for it. And the inertial system should be able to tell you quite rapidly what is going on.

However, the GPS alone is indeed useless. It's lag is too large. It can be cozened into giving you real velocity figures. The accuracy may not be as much as you like. (Three GPS antennas and differential phase tracking GPS can give you plane attitude, on large planes, fairly accurately, too.) GPS's main fault is that it tells you where you were not necessarily where you are. That's why you have Kalman filters and inertial navigation systems in the picture.

(And, yes, bienville, I do have a half a notion of what I am talking about with GPS.)

JD-EE

28th May 2011, 19:59

GY, maybe this answers some questions?

At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]". Note 1: The angle of attack is the angle between the airflow and longitudinal axis of the airplane. This information is not presented to pilots.

Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.

The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees

This is the important part: "The PF made nose-down control inputs and alternately left and right roll inputs."

The PF did indeed stick the nose down. It didn't work.

Tailspin Turtle

28th May 2011, 20:00

An acquaintance of mine was once making a routine test flight in a helicopter under development. In the brief, he had been reminded by engineering that high-inertia rotor blades were installed (not part of the test) and therefore not to let the rotor rpm get too high. During the flight, which involved shutting down an engine, he was presented with an unanticipated failure/condition with the rotor tachometer going to and freezing at an overspeed indication. He raised the collective to get the rpm down and fixated on the indicated rpm. He persisted in holding the collective up even though it wasn't producing a change in the indicated rpm and the rotor had slowed well beyond the point that he should have first recognized that it was below normal. (Apocryphally, to the point where he should have been able to see the individual blades instead of a disc...)

Presumably Airbus and Air France are putting line pilots into a simulator and exposing them to the same instrument indications and aural warnings to see what they do.

My understanding is that the side sticks are not connected and have limited range of motion so the pilot not flying and the pilot(s) observing have no idea what the control inputs of the pilot flying are. If the pilot flying were doing the inexplicable, they wouldn't be able to tell?

Level100

28th May 2011, 20:02

many thanks for link on pitch and AOA. as a SLF myself i have followed the AF447 thread from the beginning on PPRUNE. may i ask what is TOGA and the ISIS display. thankdear Foster 23
TOGA = Take-off Go-Around (thrust setting)
ISIS= integrated stand-by instrument system
:ok:

vapilot2004

28th May 2011, 20:04

JD-EE

28th May 2011, 20:06

takata, I add the PF made a nose down movement at 2:10:16. That's an important item and should not be ignored.

BJ-ENG

28th May 2011, 20:06

Post #237 (Svarin) and post #260 (mm43) are both recommended reading.

Re #237 : Svarin's speculation has a certain uncomfortable ring of truth. Protection mechanisms can be a doubled edged, and can often bite when one of those 'unknown unknowns' comes out of the woodwork. Post #4 in "Not good in an ETOPS/EROPS TWIN" is an excellent description of a similar conflict between man and machine.

http://www.pprune.org/tech-log/432141-not-good-etops-erops-twin.html

It falls under the general category of "deadly embrace," where neither of the two control entities has both the information and the ability to resolve the problem.

JD-EE

28th May 2011, 20:09

ihg, there is a difference between "a stall is coming" and "you are stalled". When near the ground do you want to nose down BEFORE the stall?

They weren't near the ground. But were they trained for high altitude actual stalls?

JD-EE

28th May 2011, 20:10

HN39 - they hit a strong updraft?

mm43

28th May 2011, 20:13

JD-EE

The nose was never down! Have a look at post #260 (http://www.pprune.org/tech-log/452836-af447-thread-no-3-a-13.html#post6478009).

I notice a number of regular posters are quiet, which is to be expected.

BJ-ENG

Thanks for noticing!

Level100

28th May 2011, 20:18

This is the important part: "The PF made nose-down control inputs and alternately left and right roll inputs."

The PF did indeed stick the nose down. It didn't work.

JD-EE,
Possibly it was even close to start to work (decrease from 7000 fpm to 700 fpm).
We'll see in a few weeks.
But remind (as said by others) it was never in a nose-down attitude.

gatbusdriver

28th May 2011, 20:29

This was posted by fantom. I believe this to be one of the most reasoned posts in this whole thread.

He is the most capable operator of the bus I have ever seen. He is also one of the best training captains, if not the best, our company ever had. It is a great shame that he now just walks his dog!

K.I.S.S.

Why can't it just be simple? All these technical issues are very interesting but are you drilling too deep? I'm not argueing for/against the AB philosophy (for which I am the No 1 supporter; I just love the 320/330), only trying to come to terms with what actually happened.

They lost the pitots and, therefore, airspeed tapes. They had not experienced this before (I have never had a go at this at high level in the sim or the A/c). The PF chose to accept he was overspeeding and pulled the nose up. The auto-trim responded and wound in the nose-up trim. That's what it does. PF is now three minutes from crashing and the captain (probably wisely) didn't exchange seats with either of them (who knows what the turb was at the time?).

Lots of NU trim, at night, no airspeed tapes and three minutes to go.

Would you have done better?

Having spent years watching crews in the sim sorting out problems and noting the time it has taken them, three and a half minutes is not a lot.

HazelNuts39

28th May 2011, 20:35

JD-EE;

The zoom climb to FL380 described in the BEA update is fully explained by the pitch-up to 10 degrees nose-up attitude. An updraft doesn't cause an airplane to pitch up. BEA doesn't say there was an updraft, but that can be easily determined from the FDR recording.

iwrbf

28th May 2011, 20:42

Hi,

I'm not a 'bus driver, so please forgive my question:

Is a (deep) stall at this altitude with this AoA in the beginning recoverable in terms of aerodynamics and the plane's datum (fuel balance)?

augustusjeremyreborn

28th May 2011, 20:44

airspeed (a/c aft/fw speed vector) almost zero

ground speed at around 107kt

I suppose that elevators wouldn´t sustain a 16º pitch-up in such conditions if the weight was in the right place.

On the other hand, I also suppose that the (fixed part of the) horizontal stabilizer would be of some help on pitching the a/c down with a 107 kt ground speed (air against the HS, c.g in the right place, center of pressure on the wings - should work like a lever)

Maybe automation is not the culprit this time. Honestly.

ask26

28th May 2011, 20:45

foster23

28th May 2011, 20:46

hi thanks for your reply. could you please tell me how the ISIS operates:ok:

overthewing

28th May 2011, 20:48

Possibly a foolish question (SLF here), but why did the plane describe an almost complete circle on its descent? Is this just to do with the roll oscillations?

spagiola

28th May 2011, 21:01

The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees

This is the important part: "The PF made nose-down control inputs and alternately left and right roll inputs." The PF did indeed stick the nose down. It didn't work.

Why do you say it didn't work? Right after the part you highlight, it says: "The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min". Seems to me (from the little we are told here) that it WAS working.

Problem is, the very next para goes on to say: "The PF continues to order pitch up" so at some point the PF had evidently gone from giving nose-down inputs back to giving nose-up inputs. Why? This is all within the first minute, so those pitch-down inputs cannot have lasted very long.

Now, the stall horn did go off as the A330 reached 37,500 feet, that is shortly after (at least in the narrative) the pitch down commands. Is this what you mean by "it didn't work?" More to the point, could the PF have interpreted this as indicating that pitch down "didn't work"?

But what is surprising about a stall horn going off when a heavy airplane has just climbed rapidly above the cruise altitude that the very same PF had, just a few minutes earlier, say they could not climb above, probably losing speed in the process, as well as increasing its AOA? It seems to me (admittedly from the comfort of my couch) that the reaction should have been: I haven't solved the problem yet, and need to keep at it.

Teddy Robinson

28th May 2011, 21:03

Nobody has mentioned "deep stall" in any published information so far released.
The only mention seen is through conjecture on these forums.

My limited understanding of the phenomena is that this aircraft layout and configuration is not susceptible to that phenomena; my recollection of initial type rating training (A320) was that it was demonstrated (in the sim) that the aircraft could be stalled, and that recovery was conventional.
There is, in other words no high tail to be masked by turbulent flow.

The video of the Tarom A300 incident on the sister forum seems to bear this out, the aircraft stalled and recovered at a comparatively low altitude.
(credit to the cabin crew for the ice cool cabin p/a btw .. she must have been very shaken).

With the initial findings released, there seem to be many complex layers to the Swiss Cheese, hence, this will take time for the full ramifications to be distilled out.

(I take on board the comments below regarding the position of he THS, it has indeed a very powerful influence on commanded pitch vs available control Authority .. that did not seem evident in my reading of the Tarom incident)

CogSim

28th May 2011, 21:04

Fixation can take over, and deafen you to the guy yelling "roll left" directly in your right ear.

Here it seems the entire crew were aware they were on the way down without knowing why or anybody offering any ideas on how to change the situation for the better.

The PF chose to accept he was overspeeding and pulled the nose up.

The sad thing is PNF seemed to be more aware of what was going on. Very early on in the sequence PNF effectively declares, we are in UAS regime and we've lost protections. PF never acknowledges. I think it was so close to AP/ATHR disconnect, that PF was fixated on trying to make his own assessment of the situation. It seems it never registered with PF that they were in UAS and/or ALT2. His actions are inline with believing either he was overspeeding or was in Normal Law. (doesn't matter which one)

Close to 2 minutes later when PF finally declares he cannot believe his instruments, it was too late, he had put the a/c in a stall regime.

The stall warning coming back when they pitched nose down didn't help either. The initial response from the PF may have been wrong, but then on it was a concerted effort by PF and computer to hold the a/c in a stall.

Very sad... :{

Clandestino

28th May 2011, 21:07

We're not much wiser after reading the latest report and won't be until DFDR trace and comprehensive CVR transcript are released!

The PF did indeed stick the nose down. It didn't work.

Because THS got 1° shy of full nose-up trim and remained so throughout the descent, all the way to splashdown.

I'll release virtual dogs of hell upon anyone who even hints that DP Davies is old-fashioned irrelevant in our day and age!

horizontal stabilizer ineffective (...) fixed part of the horizontal stabilizer I'll assume English is not your mother tongue and you're familiar with A330 yet the intended meaning of your post got somehow lost in translation.

To set the record straight: horizontal stabilizer is very effective and it has no fixed part whatsoever.

spagiola

28th May 2011, 21:14

Very early on in the sequence PNF effectively declares, we are in UAS regime and we've lost protections. PF never acknowledges.

Careful. We have obviously been given a VERY partial transcript of conversations in that cockpit. We don't KNOW that he never acknowledges.

syseng68k

28th May 2011, 21:14

deSitter, #402

Well my animus for software "engineering" is hereby exhibited - all the
fancy laws and protection modes had the precise effect of sending 228
people to the bottom because they dealt with meaningless abstractions,
not a real world problem. -drl

Sorry, another unpalatable plate of tripe. If you were a professional in
any discipline, you would realise that such areas of work always have
unwritten rules that govern personal ethics and due diligence in all aspects
of the work. Such people are dedicated and to suggest otherwise, cast
aspersions etc, says more about you than any of the people that design
airbus products. Sure, they get it wrong sometimes, but that's what it
means to be human and yes, some aircraft will crash and result in loss
of life; that fact will never change. Check out actuarial data if you
want to see the reality, but also see how safe aviation is in comparison
to other modes of transport.

Try also to remember that software is mechanistic, stupid and at the bottom
of a very deep tree. For avionics, it is a machine reflection of the laws
that were designed into it by systems, aeronautics, airframe, power plant
and a host of other engineering disciplines, each of which will have a
team of specialists to decide the best approach.

As i've said before, it's easy to design a system where it's assumed
that there will never be faulty data or failures, but as
requirements get ever more complex and more systems must be connected
together, handling edge and failure cases in a predictable manner
becomes more and more difficult to provide for and to prove correct.
If you don't build capability to handle all the extreme cases into the
system, then there is no code to execute for that extreme case. By code
here, I mean overall system coordination and behaviour. Since there are
probably millions of possibilities in terms of the sequence of events
leading to an aircraft crash, it's not possible to design any system to
automatically handle all of them.

bearfoil

28th May 2011, 21:15

bonjour ami

takata........

Hi bear,
Quote:
Originally Posted by bearfoil
"...Many posts discuss the continuous back stick..."
Please show where in the BEA report this is stated.......

0210:05...The airplane began to roll to the right and the PF made a (ONE) left nose-up input.
0210:51...The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs (Plural, more than one) ...The PF continued to make nose-up input(s). The airplane’s altitude reached its maximum of about 38,000 ft...
0211:40...The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
[French: 0211:40...Le PF exerce une action sur le manche en butée à gauche et à cabrer, qui dure environ 30 secondes.]
"en butée à gauche et à cabrer"= full deflection, stick left and nose-up (during 30 seconds)."
************************************************************ ***

AoA is sensitive to airflow in more than one direction. Initially, what appears to be a bunk move may be an aviator's attempt to hold altitude and airspeed in remarkable AIR. He has a/s to barter, and adds TOGA for good measure.

Let's for goodness' sake lose this barking dog mentality, and give the PF some credit.

I read from BEA that the PF made REPEATED inputs (NU), not sustained.....

different perspective.......

What would explain the need for constant roll left, to maintain SL?

damage? AIR ? cg? Likewise NU? cg? ICE? All we see is the response, not the stimulus.

infrequentflyer789

28th May 2011, 21:20

China Airlines Airbus Industrie A300B4-622R, Nagoya Airport April 26, 1994
Bournemouth Airport, U.K. - A Thomsonfly (now known as Thomson Airways) Boeing 737-300 with 132 passengers on a flight from Faro in Portugal to Bournemouth in England, September 2007
An Air New Zealand Airbus A320-200, registration D-AXLA (ZK-OJL), test flight GXL888T from Perpignan (France), Nov 2008
Turkish Airlines Boeing 737-800 at Amsterdam's Schiphol Airport, February 2009

etc etc All aircraft which crashed (or very nearly so) because the pilots failed to realise that the trim had been set full nose up, and couldn't understand why they lost pitch control.

Generally airline stall recovery training doesn't use or show a set up with the trim set this way - it is usually an artificial "OK, we are going to stall ... disengage the autopilot and slow the aircraft down, and stop trimming to allow for the recovery..."

Agreed, it's a nasty pattern developing, and nothing to do with A vs B or FBW (everything to do with higher-level automation though).

However, it isn't at all clear that 447 fits this pattern. The trim up in this case is after the a/p drops out, and in response to pilot inputs. Initially at least, auto-trim is still active, and responding to nose up (to the stops) stick input.

It remains unknown from what info the BEA choses to give us at this point whether or not other control law transitions took place which might have kicked auto-trim out later. I think if direct law had engaged it would be clear and would have been reported - but I am not so sure about abnormal attitude law, looks like at some points at least they should have been in it, but BEA does not mention, possibly still trying to determine that.

One thing that does look clear, is that regardless of what the THS did, when they put the stick forward, it sounds like the a/c responded - reducing the pitch. It would appear the inputs were never held long enough to actually put the nose down.

Or in other words, from what info we have, it doesn't look like they lost pitch authority.

mm43

28th May 2011, 21:20

Teddy Robinson
Nobody has mentioned "deep stall" in any published information so far released. You are absolutely correct, and even though I have used the term, it was describing the attitude the aircraft was being "held" in. They were not "cast" and were capable of correcting this, but were as this Antipodean would put it, "Transfixed like a possum caught in the headlights".:sad:

infrequentflyer789

28th May 2011, 21:22

All

1. Could the auto flight system be re-engaged in the stall ?

2. If so , would Alpha floor pulled them out of the stall ?

Mixing up autopilot and protections/laws there. As I understand it A/P can be re-engaged in alternate law (once you've recovered stall), but normal law will not re-engage for the rest of the flight, so no protections (except g-load).

gums

28th May 2011, 21:25

One poster asked if it was possible to get into a stall and not be able to recover.

Answer? Yep.

So see this old post from thread 2 once we got thru all the search procedures, pinger characteristics, FDR construction, etc.

http://www.pprune.org/tech-log/449639-af-447-search-resume-part2-39.html#post6432295

It is entirely possible that even full nose down elevator commands in Direct law could not provide a high enough pitch coefficient to break the stall. This could be due to the THS being trimmed almost all the way to a nose up command and the relatively small surface area of the elevators. Until I see a good pitch moment chart as the one I posted for the Viper, I'll reserve further speculation and only say that it is indeed possible.

I also point out the "golden arm" test pilot's description of the "ride" when in a fully developed deep stall. Any resemblance to the AF447 profile from 35,000 feet to impact is purely coincidental, heh heh.

Gums sends...

post seemed to be edited by "janitor" for a crass "You Tube" reference. LOL.

Clandestino

28th May 2011, 21:27

It is a capital mistake to theorize before you have all the evidence. It biases the judgment.

DFDR does record FBW law. Patience is the keyword.

glad rag

28th May 2011, 21:34

:ok:
Could that desire not to lose altitude be linked due to the weather deviation,(which I think could be one of the psychological factors affecting the PF's initial reaction) in that they were just clearing the tops of a cell and were worried about the subsequent impact of losing it. Hence the application of TOGA to attempt to compensate for the pitch up.You know, you may be so on the money.

All the "haters" on here can't even recognise a simple human decision, a decision made in an attempt to avoid further "difficulties".

augustusjeremyreborn

28th May 2011, 21:35

clandestino:

To set the record straight: horizontal stabilizer is very effective and it has no fixed part whatsoever.

You are right. It is trimmable and it was 13 degrees down (pitching-up). With 107 kts ground speed it could maintain a 16 degrees a/c pitch-up attitude.

Let's get back to automation, then...

P.S.:

Somebody must have asked this before:

If the trim was not performed by the PF but by HAL would the PF be easily aware of this ?

infrequentflyer789

28th May 2011, 21:38

- Hey HAL your air speed dropped from 275knots to 60 knots WITHOUT any decceleration!

-So disregard your speed change and keep the current flying parameters - thrust and pitch. Until deceleration/acceleration tells it that speed changed.

And then give pilots info about unrelaible airspeed.

Which is what it does, and what happened. With the addition that because speed is known-bad the speed-based protections drop out. And control gets handed to the pilots - because HAL isn't sure what the plane is doing any more.

With no control inputs, the plane should just keep doing what it was doing before, here something causes a roll and pilot responds with full back stick and all hell breaks loose.

theav8tr

28th May 2011, 21:41

I have to wonder if the initial thought of the PF was (after auto pilot, A/T disengage) to not let the aircraft increase its speed due to the anticipated turbulence upcoming. Remember there was a crew communication to the cabin about "it'll move about a bit more than at the moment" (2h06m04), along with the crew deciding to reduce speed from .82 to .80 a few minutes later (2h08m07) due to the anticipation of turbulence - "turbulence increases slightly". About 2 minutes later is when the A/P and A/T disconnect and the speed drops from 275kt to 60kt and a few seconds later the crew identified "so, we've lost the speeds". So now recognizing that they had invalid speeds, and knowing they needed to avoid penetrating the turbulence at too high of a speed, I wonder if the initial thought was to apply nose up inputs to ensure turbulence penetration speed was not exceeded. I also have to wonder with this being fresh on their mind, it might have been their initial concern when losing the speed indications, that we can't penetrate the weather at too fast a speed. Then while troubleshooting and dealing with everything going on and possibly being distracted, realized there was too much nose up input and went to nose down (7000ft/min to 700ft/min) You also have to wonder if through this whole ordeal, if that was something they were fighting if they were in IMC conditions and rough air for most of the 3 1/2 minutes.

Right or wrong, I just know that the weather and reducing speed was fresh on their mind. When the A/P and A/T disengaged, maybe there was zero panic and they were confident how to handle the situation and simply were going to wait for the speeds to come back. The other thing that caught my attention...was the crew briefing just before the captain left. The briefing from crew, was that they couldn't climb right now "we’re in the cloud layer unfortunately we can’t climb much
for the moment because the temperature is falling more slowly than forecast" - So I have to wonder if that is something they had discussed earlier about possibly trying to climb above the current cloud layer, but couldn't due to conditions and aircraft config at the time. When they lost the speeds, I wonder if there was a thought of trying to climb if they could to see if they could get to 1)smoother air and 2)out of the cloud layer to hopefully clear the pitot sensors.

I am probably reading between the lines, and CVR recordings would help to identify some of this. I just find it interesting that climbing was part of the crew briefing.

So did the PF try to pitch up slightly to keep the aircraft speed below .80 since they were now more than likely penetrating turbulent air? And was there a desire to see if they could get to a higher altitude (out of IMC) to help resolve the issue with the speed sensors? Again right or wrong from SOP, but it could point to one of the reasons of nose up initially. Once they entered a stall, that created a whole host of other challenges.

I haven't flown in a few years and only flew corporate jets for several years, but the mindset of the pilots will be very hard to decipher even with CVR recordings, which will help to paint a better picture of what they were thinking. I want to be able to give the pilots the benefit of the doubt and would like to think that there was some logic in the initial nose up and at other times nose up commands. As pilots, we need to be supportive of each other, and realize that many of us have been fortunate enough to not have to deal with a "hairy" cockpit in our careers. But for those that have, like this crew, we have no idea what was going through their heads.

bearfoil

28th May 2011, 21:42

So who has eliminated all but UAS? What was PF's initial control input, a rather robust response and result. What caused his reaction? Did a/p drop before or after, and either way, was its involuntary loss linked to the manouver? The conditions in the cell? Fixation is neurotic........and leads to accusations and unsupportable claims. Just for review, a Stall warning is not necessarily a Stall.

MountainBear

28th May 2011, 21:42

Having spent years watching crews in the sim sorting out problems and noting the time it has taken them, three and a half minutes is not a lot.It depends on how you look at it. Four minutes is a lot of time for two pilots to be startled or surprised. It's not a lot of time for pilots who are confused. I think it's important to be quite clear and specific in regard to the terminology used.

In any event, I think the time issue is a red herring. What the flight crew should be judged upon is not the length of time they had but how they utilized the time they did have. Was their behavior in accordance with their training? Was it up to professional standards? The fact that there was only four minutes before the plane crashed was not a predetermined parameter set in some sim session; those four minutes were a function of the flight crew's inability to prevent and then recover from a stall.

HazelNuts39

28th May 2011, 21:46

Nobody has mentioned "deep stall" in any published information so far released. That depends on how you define "deep stall". From BEA's Update Findings: - the descent lasted 3 min 30, during which the airplane remained stalled. The angle of attack increased and remained above 35 degrees, (...).
The last recorded values were a pitch attitude of 16.2 degrees nose-up, a roll angle of 5.3 degrees left and a vertical speed of -10,912 ft/min. For a groundspeed of 107 kt, the last recorded values (assuming no wind) correspond to a flight path angle of 45 degrees down, i.e. an AoA of 61.2 degrees. Deep?

JD-EE

28th May 2011, 21:54

mm43, nose never down notwithstanding the PF pushed the stick forward.

At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".

The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased
sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees.

The plane was stable for about 35 seconds before another stall warning, which may be appropriate given speed and altitude. What happened next seems to make no sense. I also wonder why PF did not push stick forward again to initiate a descent back to FL370, which would be safe and beneficial given the speed report that returned. Of course, he may not have trusted it.

JD-EE

28th May 2011, 22:03

At 2 h 08 min 07 , the PNF said "you can maybe go a little to the left […]". The airplane began a slight turn to the left, the change in relation to the initial route being about 12 degrees. The level of turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8.

Nothing there to pull the nose up.

From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input.

The nose-up input - would that be to maintain altitude while correcting the roll? It does not say how large a nose-up input was made for how long.

At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".

...

The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs.

If the PF had not made a very assertive nose up what brought the nose up 6 whole degrees on a plane with that mass? (Mind you, I am not at all sure an updraft would lift the nose.)

(And I keep quoting because it seems some of us are not working off the same document. That way the source of my confusion is at least well delineated. I'm not trying to be a smartass - except maybe to bienville. He twisted my tail.)

JJFFC

28th May 2011, 22:06

"A formal document detailing the rationale for the revision points out: "There have been numerous situations where flight crews did not prioritise [nose-down pitch control] and instead prioritised power and maintaining altitude."
Operational experience has shown that fixating on altitude, rather than the crucial angle of attack, can result in an aircraft stalling."
Revised stall procedures centre on angle-of-attack not power (http://www.flightglobal.com/articles/2011/05/28/357321/revised-stall-procedures-centre-on-angle-of-attack-not.html)

A pilot that doesn't nose down immediately when earing a stall warning has not understood what is a stall : the plane is no longer a plane, it is a cucumber.

When you ear a stall warning, you are about to die within a min => you don't even remember your name : you nose down.

The trouble is that :

" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."

REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb

gums

28th May 2011, 22:07

Hazel, et al.

I re-posted the deep stall stuff an hour ago.

JD-EE

28th May 2011, 22:13

CogSim, good catch on the PF never acknowledging the PNF statements. It certainly does seem to match a hypothesis that PF was fixated on the unitial WTF moment.

Clandestino, the initial nose down command was way before the THS was stuck at 13 degrees. That started about 35 seconds later in the sequence at 2:10:51. And as I read it 2:10:51 was the start of THS movement from 3 degrees to 13 degrees.

{^_^}

Teddy Robinson

28th May 2011, 22:23

that, quite possibly, could be the conclusion drawn based on what has been released so far, still, until the investigation process has properly run it's course, and the full transcript released set in context, on a time line, it is all too easy to draw conclusions, when there are levels of other systemic failures that are not so easily identified.

I would expect the rate of BEA press releases to slow down from this point until the release of an interim report.

Re: deep stall, at this point, unless the term is specifically used by BEA, it remains conjecture. High A of A, high descent rate, low forward speed may fit the base line criteria for a deep stall condition, however, the term used is a recognised condition, which until officially cited by the investigation as affecting the airframe, on a type and configuration not usually affected by the phenomenon, may be a reasonable descriptive term in conversational terms ... but ...

Sorry for being pedantic.

cwatters

28th May 2011, 22:24

Clipped from an earlier post..

From 2:10:05 — The autopilot and auto-thrust disengaged and the PF said, "I have the controls." The airplane began to roll to the right and the PF tried to raise the nose up and to the left. The stall warning sounded twice in a row. Recorded parameters show a sharp fall in speed.

2:10:16 — The PNF said "so, we've lost the speeds" then "alternate law

Thats less than 11 seconds from tripping the autopilot to a stall warning. I'm not a jet pilot but that sounds quite fast. Is it?

bearfoil

28th May 2011, 22:27

JD-EE

From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input.

02:10:05...The airplane began to roll to the right and the PF made a (ONE) left nose-up input.

Mademoiselle, M'aider, sil vous plait? Qu est-ce que c'est? La meme chose temps?

The pilot corrects for what the a/p had trimmed out, a right roll and down Pitch.

At a subsequent time, they note the speeds are belly, and the climb commences. These events are linked, yes? I note also the similar input at the top of the climb. Do we know this aberrant non-cruise event is ICE related?

I appreciate your collating the chronologue, it is very helpful. Has anyone posted the possible encoutered verticals in a cell?

A33Zab

28th May 2011, 22:32

Svarin post #237 http://www.pprune.org/tech-log/452836-af447-thread-no-3-a-12.html#post6477847

Three out of five components of the Flight Controls System have suffered anomalies :

- PRIM2 suffered a connectivity problem with ADR1, such problem is deemed HARD, which means permanent, not transient.
- PRIM1 stopped operating.
- SEC1 stopped operating.

These anomalies have consequences which can be verified using the Flight Controls Reconfiguration Schematics from FCOM chapter 27 :

- PRIM2 is tasked with THS motor because PRIM1 quit.
- PRIM2 is tasked with both elevator halves because both PRIM1 & SEC1 quit.

Additionally, PRIM2 operation is polluted because it lost connectivity with ADR1, thus reducing its discriminating capability while simultaneously getting fed multiple erroneous ADR data.

This simultaneous double failure condition : connectivity + erroneous data, is an extremely serious issue. I very much doubt that such apparently unrelated, simultaneous, totally different failures (external cause -> icing + internal cause -> wiring) were ever considered together during the design phase of the Flight Control System.

This extraordinary combination precisely affected the one computer which ended up being tasked with :
- interpreting sidestick commands on the pitch axis.
- sending orders to the hydraulic servo jacks located on the elevator moving parts.
- sending orders to the electric THS motor.
- providing whatever "protection" it deemed necessary to provide while in its undefined state (unreliable ADR data + lost connectivity with one ADR)

In the bold is exactly what in a normal situation PRIM 1 is capable to perform, so shouldn't be a problem for PRIM 2 too.

What I can add to your intresting observation is that in this situation, due to loss of the FCPC1(PRIM1) and FCSC1(SEC1), the Inboard (Green) servos are totally lost (both servos in dampening mode) and therefore are unable to assist the outer servos(BLUE/YELLOW) in large elevator deflections.

From the Technical Training Manual:

PITCH D/O (ELEVATOR) (3)

ELEVATORS NORMAL OPERATION

Each elevator servocontrol is connected to two computers (one FCPC
and one FCSC).
In the normal configuration, the inboard servocontrol is in active mode
while the outboard is in damping mode.
FCPC 1 having the servo-loop control priority:
- sets its dedicated servocontrol in active mode and ensures the servoloop control,
- commands the damping mode on the adjacent servocontrol (one solenoid valve (S) energized).
For the elevator servolooping computation the computers need to acquire:
- the elevator surface position,
- the elevator servocontrol piston position.
This information is sent by servocontrol transducers (XDCRs) units and
the surface position transducer (RVDT).
In the event of large deflection demands, the two servo-controls can
become active to avoid the saturation of one servocontrol.

ELEVATORS ABNORMAL OPERATIONS

HYDRAULIC OR ELECTRICAL FAILURE
If a servocontrol being in active mode is either not hydraulically powered
or not electrically controlled anymore,
the faulty servocontrol falls in damping mode and the adjacent one
becomes active according the servoloop reconfiguration.
If both servocontrols of one elevator are depressurized, both servocontrols are in damping mode which prevents fluttering.
When P1, P2, S1 and S2 are no longer able to control their dedicated
servocontrol (ie: inputs missing, electrical failure, etc...), the servocontrols fall in re-centering mode

HazelNuts39

28th May 2011, 22:34

Many people are wondering if as is speculated why the PF pulled up as one of his initial actions. I think on Page 1 of this particular thread one explanation has already been given:
"If he thought he still had stall protection, would commanding pitch up be a way of trying to tell the aircraft: I don't want to lose altitude, and I'm relying on you not to let me stall?"
Could that desire not to lose altitude be linked due to the weather deviation, (which I think could be one of the psychological factors affecting the PF's initial reaction) in that they were just clearing the tops of a cell and were worried about the subsequent impact of losing it. Hence the application of TOGA to attempt to compensate for the pitch up.

The sad thing is PNF seemed to be more aware of what was going on. Very early on in the sequence PNF effectively declares, we are in UAS regime and we've lost protections. PF never acknowledges.

These inputs made me think of the Recovery Technique in windshear/downburst conditions (close to the ground), where the pilot is (rightly) encouraged to rely on the High-AoA protections in Normal Law (FCOM 3.04.91, but my copy may not be up-to-date: - Thrust levers: TOGA; - Follow SRS orders (including use of full back stick if demanded) - Note: If SRS is not available, initially use pitch attitude up to 12.5° but this pitch attitude can be increased by using full back stick if necessary to minimize loss of height.

syseng68k

28th May 2011, 22:37

bearfoil:

From 2 h 10 min 05, the autopilot then auto-thrust disengaged
Apologies for butting in, but under what cicumstances or failure modes do these disengage, assuming not the action of the crew ?.

Trying to think logically: This is the first event in the chain. If we know the conditions under which the two disengage, perhaps we can work back from there ?...

Clandestino

28th May 2011, 22:37

the initial nose down command was way before the THS was stuck at 13 degrees. That started about 35 seconds later in the sequence at 2:10:51. And as I read it 2:10:51 was the start of THS movement from 3 degrees to 13 degrees.

1. that what you're referring to, sir, is in no way officially connected with BEA and it might be realistic representation of DFDR data or it might not.

2. if, and it's a big if, it's correct and accurate, trim started moving at 2:10:50 and stopped at 2:11:51. Apart from comments about giving mostly climb commands, it can't be seen what was the sidestick displacement or what sidestick was active at all during the period.

3. while we wait for DFDR traces, I'd like to once more remind fellow PPRuNers about AC Doyle's warning on theorizing without facts, the one I've quoted a couple of posts ago.

Teddy Robinson

28th May 2011, 22:42

while we wait for DFDR traces, I'd like to once more remind fellow PPRuNers about AC Doyle's warning on theorizing without facts, the one I've quoted a couple of posts ago.

CogSim

28th May 2011, 22:47

So who has eliminated all but UAS?

PNF.

PNF said "so, we’ve lost the speeds" then "alternate law [...]".

What was PF's initial control input, a rather robust response and result.

The airplane began to roll to the right and the PF made a left nose-up input.

initial input: left nose-up
response: The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb.
result: vertical speed, (which) had reached 7,000 ft/min

Did a/p drop before or after, and either way, was its involuntary loss linked to the manouver? The conditions in the cell?

From 2 h 10 min 05 (4), the autopilot then auto-thrust disengaged and the PF said "I have the controls".

As I read it, PF taking control was a response to AP/ATHR disconnect.

PNF's assessment seems to corroborate the evidence that AP disconnect is linked to loss of airspeed: PNF said "so, we’ve lost the speeds" then "alternate law [...]".

Fixation is neurotic........and leads to accusations and unsupportable claims. Just for review, a Stall warning is not necessarily a Stall.

From 2 h 10 min 05(4), the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS).
Note 1: Only the speeds displayed on the left PFD and the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded.
Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight. At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law [...]".

The crew seem to agree with your assessment. Their actions and comments seem to ignore the first stall warning here.

Stall warning comes from the angle of attack sensors, not the airspeed indicators - so a stall warning with an indicated high speed is possible.

Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.

Does this mean in Normal Law stall warning is coming from airspeed?

Zorin_75

28th May 2011, 22:50

CogSim, good catch on the PF never acknowledging the PNF statements.
You don't seriously think that what's in the BEA note is all of the communication in the cockpit, do you?

PT6Driver

28th May 2011, 22:54

JDEE - When PF initialy reduced the VS from 7000 to 700 the aircraft had not actualy stalled. The first stall warnings were false due to the eroneous speed indications. These also led to the AP and ATHR disconects and the reversion to alternate law. Therefore his actions to reduce the climb were partialy sucessfull. If you mean his actions did not unstall the aircraft as I said they were not stalled at this point.

Later on the PF made pitch down movements which resulted in reduced AoA and increased speed - therefore the situation was recoverable.

Cog sim - the computer had nothing to do with maintaining the stall as PF was able to reduce pitch when he chose so to do.

Would anyone care to comment on how many times during their career they have experienced an uncomanded reversion to alt law?

What is the stall speed at FL380, 350, 300, 200, 100 sea level?

Some one mentioned earlier the colgan crash and I have to agree there are similarities in that in both cases the PF would apear to have reacted incorectly to impending and actual stall. - No one plans to stall for real, accidental stalls ocur when we least expect them and are probably most unprepared for them. In order to survive quick recognition of the situation followed by apropriate response.
This in turn derives from the training - if this is inadequate or inapropriate then the wrong responses follow.

Zorin_75

28th May 2011, 22:58

Does this mean in Normal Law stall warning is coming from airspeed?
This means in normal law AoA protection is active (which should prevent a stall in the first place).

ask26

28th May 2011, 23:01

I think myself and theav8tr are thinking along the same lines. When it's a long flight, boredom in the cockpit and one overriding thing is there to focus the mind, in this instance the oncoming weather, all the mental ideas you have go into solving that problem.

I think the initial loss of A/P and A/T weren't the problem but a mental desire to get out of the icing layer/weather and certainly to not descend and enter even worse bad weather. Hence the initial response to climb and I believe initial pull-up actions.

Any later pilot responses to a stall warning that may have followed is another matter but I think that is one possible explanation of the primary actions taken by the crew i.e. nose -up input, and is being mistaken here as an incorrect response to the stall.

CogSim

28th May 2011, 23:04

Cog sim - the computer had nothing to do with maintaining the stall as PF was able to reduce pitch when he chose so to do.

in this statement computer = auto-trim and stall warning disappearing/reappearing below/above 60kt threshold.

What I perhaps should have said is the "computer" as defined above, was making it gradually more difficult for the crew to get out of it.

widmimabi

28th May 2011, 23:07

:cool:No that's the normal overspeed Protection but Nobody on this thread is speaking about the proper reaction in case of unreliAble airspeed : pitch and power ( about 2.5 degrees pitch and 85/100 n1) and then switch out the faulty ADR . And surely not climbing 3000 ft at Max FL , trying to stop the airspeed( the faulty one ) from accelerating

promani

28th May 2011, 23:07

"CogSim, good catch on the PF never acknowledging the PNF statements"

With only fifteen snippets of conversation released by BEA from about the last twenty minutes of recordings, maybe it is bit premature to accept that as fact

grizzled

28th May 2011, 23:14

JD-EE and CogSim,

At this stage I wouldn't put much weight on what we know of crew interactions (i.e. one crew member acknowledging or not acknowledging another's words). The words of the crew released by BEA would have been selected to provide some context (not all by any means) to assist us (the public) in understanding the most basic aspects of what happened. The how's and why's are still a long way off.

In the last 10 mins of the flight -- especially the last four -- we can be certain there was a great deal of crew interaction.

CogSim

28th May 2011, 23:17

This means in normal law AoA protection is active (which should prevent a stall in the first place).

Thank you. At least the PNF was showing enough awareness to respect the stall warning.

sensor_validation

28th May 2011, 23:20

More questions raised by the BEA report, probably impossible to answer with certainty I'm afraid

1. Would the speed reduction from M0.82 to M0.80 have been completed between 2:08 and 2:10? - if not the engine speed on auto-thrust disconnect could be below that needed for maintaining steady flight. Rudder limit consistent with FL350 and M0.80, but 'about 275 kt' a little high?

2. Is it correct to assume captain would have been PNF in the left-hand seat at T/O, so the PF was in the right-hand seat - and speeds shown on right-hand-side are not recorded?

3. Am I right in thinking that the ISIS displays the air speed from the 3rd pitot? Indicated speed falling low on both left PFD and the ISIS could then be caused by pitot ram ports blocking with drain clear - leaving possibility that the right PFD has frozen ram and drain and will indicate increasing speed with increasing altitude?

4. In the A340 airprox incident an "alpha floor" protection increased engine speed to max even when autothrust disengaged - could this have happened here, possibly at time of first stall warning.

mm43

28th May 2011, 23:21

promani
With only fifteen snippets of conversation released by BEA from about the last twenty minutes of recordings, maybe it is bit premature to accept that as fact The reported conversation is "minimal" and IMO only to support the flight control inputs and disclosed aircraft response so far released.

There is much unexplained data dealing with PRIMS/SECS (per ACARS) that may lead to different explanations at a later date.

wes_wall

28th May 2011, 23:23

MM43 quote: I notice a number of regular posters are quiet, which is to be expected

I have purposefully remained silent after reading the BEA report, which is very short on detail, and which unfortunately goes along with what I expected. The French are very careful to paint any picture which might point a finger at National interests. Now, don’t take this as conspiracy related, just factual based on previous investigations. To date, they have only thrown us a bone, factually and judicially correct, but still lacking the meat which completes the actions of airplane and crew that suffered the results. What transpired during the deafening voids in the explanation sing out louder that then statement. More to come I sincerely hope. For those of us who made our living in their seats, and for those still sitting there, can probably build a defendable position on what happen, and why. We can now only hope that the evidence released and reported will be true, and will thereby accelerate the needed corrections. Until then, I fear the airplane will fly under a cloud of doubt, rather than on top where it rightfully belongs.

takata

28th May 2011, 23:35

Hi bear,
AoA is sensitive to airflow in more than one direction. Initially, what appears to be a bunk move may be an aviator's attempt to hold altitude and airspeed in remarkable AIR. He has a/s to barter, and adds TOGA for good measure.
Let's for goodness' sake lose this barking dog mentality, and give the PF some credit.
I read from BEA that the PF made REPEATED inputs (NU), not sustained.....
different perspective.......
What would explain the need for constant roll left, to maintain SL?
damage? AIR ? cg? Likewise NU? cg? ICE? All we see is the response, not the stimulus.
I do seem to remember that you had posted a very clear question.
I simply tried to answer it.
If you do think that "30 seconds of full back deflection" is not "continuous back stick", what is it?
Read yourself. You didn't ask for an explanation, but doubted that it was even written in this report.
Barking with dogs after those AF pilots is not in my mentality as I'm also looking for some reasons explaining those unfortunate PF imputs.
My perspective is different than yours as I'm looking for other factors. I would like to know how many trainings this pilot ever did involving a high altitude stall without any protection vs. recovering from a low altitude stall with full flight envelope protection. I guess he did a lot of the later but maybe, never practiced the former.
The danger is obvious as both case could use opposite imputs and a pilot only trained to one form may have reacted instinctively by the opposite move. Full back stick deflection would give Alpha_floor/Alpha_Max in one case and a full stall on the other case. All it would need is a pilot unaware that the protections won't kick in (ie. Perpignan).

GarageYears

28th May 2011, 23:38

GY, maybe this answers some questions?

Quote:
At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]". Note 1: The angle of attack is the angle between the airflow and longitudinal axis of the airplane. This information is not presented to pilots.

Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.

The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees
This is the important part: "The PF made nose-down control inputs and alternately left and right roll inputs."

The PF did indeed stick the nose down. It didn't work.

This is what caused the climb:

[quote]From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input.Irrespective of the stall warning that followed the aircraft was ALREADY in the climb that appears to have sealed it's fate. Remember STALL is a function of AoA (are you sure you understand this?).

The pitch-down stick down movements were effective, and may have saved the aircraft if continued however for some reason they were not and airspeed at this time was (presumably) bleeding off due to AoA.

Anyway it's a shame, because I'm loosing respect for some posters here since some fairly basic data points are being glossed over to make some other story match the end result.

BananaAir

28th May 2011, 23:56

No mention of the PICs negligence in leaving the flight deck prior to entering an area of severe CB activity. He had to have known that there was severe CBs in the area was there from his briefing and from listening to other aircraft deviating. Any flight over the ICTZ has a great chance of experiencing monstous CBs!
The fact that the relief pilot and the SIC made attempts to call him back to the flight deck signifies that they were overwhelmed with what they faced.
In hindsight, a 200+ mile deviation left or right of the CBs that night would have saved all the lives on that plane. As to why they didn't do this is anyone's guess.

promani

29th May 2011, 00:19

mm43

Yes I agree with you there 100%. After 2 years BEA only gives a little information, that I think to myself that they are playing games. Just teasing us. But I know that is not true. Just the way they do things.
Pity the US was not investigating this accident. Then all would be revealed, or at least most, whether or not the judiciary was involved. Oh well 2 months to go....

jcarlosgon

29th May 2011, 00:21

After the accident I went through stall, UAS, training in the sim, as per Airbus syllabus.

I was kindly allowed an extra exercise at FL350, about 170 tons, CG around 30%, about one year ago. Pull up from FL350, all 3 ADRs off, kept it at 15 degrees up till it stalled, à la B707/27/37, A310, in gone years.

THS went full back, don’t remember the figure, and sidestick was released, N1 at 85% (A/THR off). The nose came down to about -5 and went back up to +10. Rate of descent was between about 6K fpm and zero, or slight climb (sim is an A330 with PW engines, 85% is slightly above needed N1 for turbulence at M 0.80).

Recovery was done by pushing forward. The surprise, for me, was not the amount of force on the stick to keep that nose about 3 degrees down, in order to get the THS in a comfortable position, about 3 up, at, oops, about 20000’. The surprise was how so long it took. The flight controls never went from ALT to Direct Law.

Shame, I did not try it with full THS up and full forward stick in Direct Law.

Someone posted, my thanks, that stall training is done with stab trim not behind normal (scheduled) IAS for the configuration. That happened to me, even in the military. No problem at the time, no A/P, no autotrim. Problem later, with “moving stabilizer” stall, with A/P ON (B707, 727,737, A310). Same with autotrim aircraft, A320/330, if not properly handled. Check out the OEB concerning Radio Altimeter wrong reading to zero, versus stabilizer trim during go around, as well.

Let’s wait for a more complete report, CVR and flight data.