Not sure why not as icing is likely to affect all pitots at the same time. With regard to engines failing its worth looking up the Miami- Nassau Tristar or the Royal flight 146!

The missing cvr transcript
 

"Unless I missed it, nobody seems to have mentioned that the original worst-case theory--that the airplane flew into the mother and father of all ITCZ thunderstorms because it was radar-blanked by a line of cells between it and AF447--no longer seems to hold water.

Certainly 447 flew into weather that created an unusual kind of supercooled, high-altitude icing that suddenly affected the Pitots, but the CVR transcript doesn't mention anything that might be interpreted as turbulence upset--only the apparent impossibility of dealing with multiple fault warnings and anomalous displays. "

Does anybody really believe that there wasn't a lot of chatter going on in the cockpit? Especially, "What's it doing now?"

We've been given only minimal information and so far no indication that the CVR was not intact.

Another notable absence: Any reference whatsoever to the number one item: THE CHECKLIST! With everything going "off " nothing re "reset".

An Airbus Programming Error?
 

Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International

@DozyWannabe. TCAS doesn't receive any speed input whatsoever. It calculates closure rates based on comparing time it takes to send a signal and receive it back at the antenna.

Post amended because of bad wording

TCAS does have one air data input for Mode C (barometric altitude) coming from the Static Port. It would be very unusual for a Static Port (which is flush on the fuselage) to ice over.
So as a source of failure for the TCAS I think not likely.

I stand corrected - cool.

Right, so that being the case there are two questions. If TCAS doesn't require air data itself, is the way it's plumbed into the A330's avionics something to do with it? Also, at what point in the ACARS sequence did that message fire? Early on, it might raise some questions. Later, as more systems began to fail it might be a moot point.

TCAS computation needs altitude to assess threats and should receive barometric and Radio Altimeter inputs! yes/ no?

For those pondering lessons from this accident:

Its probably been said before in the last 55 pages but,

If you lose sensible airspeed and altimeter indications, disregard all and fly attitude and zero bank angle for normal cruise flight with relevant manual throttle setting. Been there, done that.

Try it in the sim.

With the few precious facts that we have a this moment, why make stuff up that even contradicts those?
At the beginning of the climb:
- alternate law
- THS 3 deg up
- nose up input from PF

If the airspeed data was erroneous/unavailable for 50 seconds or so and then became available why the aural "STALL" warning was not continuous since? I think an audible "STALL" and "SINK RATE" would be more than enough to get the crew aware. The question is: why there were no such alarms? Or why it sounded only when the sidestick was pushed forward, supposedly breaking away from the stall, or at least relieving it? Maybe I'm missing something...

According to common logic and some data on the net, the answer must be "YES". So yes, the TCAS must have failed due to bad (inconsistent?) altitude data, but whether the data was really wrong or the source of the data just stopped functioning, is impossible to tell.

When searching the net for this topic, I came to this youtube link called "Part of the series of 32 training videos of the A320. [17] IR 1 Fault IR Dis" This video is not for the faint of heart. Captain and co-pilot are going through FIVE MINUTES of checklists related to the failure of the system providing flight data... Maybe this checklist is doable in the safety of the simulator & VFR conditions when one can see the horizon... But I don't believe such a checklist can be completed over the ocean at night, with thunderstorms around, the plane out of control, multiple other alarms and the captain not in the cockpit!!!

@ Aeromech, post corrected because of course you are right and I should not have used no ''Air Date Input'', just no input from the Pitot probes

@ST27There is no way an a/c at 38000 ft is going to decelerate fron Mach 0.82 to a virtual standstill in 30s. Imagine the forces on the flightcrew: why would they proceed? If they try, it'll stall well before the standstill.

The BEA report simply doesn't contain much information. Don't read too much into it.

Undiagnosed emergenzy check-list?
 

I just wonder if there exist such a thing as a "stall checklist" or even a "general catastrophic -check-list" that is designed to reveal - to the perhaps bewildered crew the true state of the flight.

I'm talking about a checklist that designed to be used in the situation where the captain returned to the cockpit in this flight. The situation that he may not have realized the true state of the flight.

Take a lesson from emergency medicine (where I have some expreience) . Whenever a traumatized patients is hospitalized something called Triage is performed. To help the doctors cope with the situation a simple A-B -C -D -rule is performed. This procedure is trained regularly - so it will pop up in the minds of all involved and also direct the treatment of the patient. So here goes:
A -- Airways - - Are the airways open and and not threatened (as by unconciousness or blod - swelling /injury etc) --> if yes continue --> if No - Intubate - open airways - cricotomy --once fixed-- go to B
B: Breathing : Is patient breathing good - if yes go to C -- If no -- clear the situation --> tension pneumothorax? Collapsed lungs ? -Chest Xray- Apply chest tube
C: Circulation --> Stable blood pressure? - Signs of major bleeding?Substitute fluids/blood. Stop any major bleeding --> emergency surgery to control bleeding.
D: Disability - Severe injury? - fractures? wounds? Neurological damage? CT-scans - X-rays - surgery to treat fractures etc
E: Minor injury - can wait to diagnose and treat

This rule was invented when one realized that patients died in CT-scan- machines etc because of bleeding - instead of being brought directly to surgery when indicated

So what would be the analogue within aviation? Please notice that in this checklist A-B-C is concerned with stabilizing the patient - so he will not die within minutes. D: is only performed when A-B-and C (stability -at least temporal ) is achieved. Pleas also notice that this procedure is done with with the full attention of all involved. If the patient is stable (not severely injured)- A-B-C will not take long time to establish - it its a critically ill patient surgery for A-B-C may take lot of efforts- lot of surgery - lot of time.

May I suggest : A- for Angle of Attack?

Many moons ago I had a LHS pitot heat failue in an F50.
We were near top of descent when it happened, it was daylight, and I was aware of the consequences if we flew into icing.
We were in clear air, but I gave control to the F/O.

On descent we encountered a thin layer of cloud. We had no alternative - it was a continuous deck.
Within seconds of entering the layer (we went IMC) my airspeed suddenly rocketed upward toward VMO. It oscillated there for a few seconds then rapidly returned to an about normal reading.
Although I expected it, although I knew what was happening, although I had a good ADI in front of me - still - every fibre of my piloting instinct was screaming at me to pitch up to prevent the overspeed I was witnessing.

Of course, I didn't.
But - I was in daylight (even if IMC) and in relatively smooth air.
My excellent F/O was flying, and had normal ASI indications from a good pitot. Nothing had happened in terms of pitch/power changes to justify this abnormal lurch in speed, so my experience over-ruled my basic piloting instinct to react.

And we were in VMC in a minute, with normal ASI readings restored on my side.

But believe me - until you have experienced this - you will never understand the shock and disorientation it can cause.
At night, at high altitude, in heavy turbulence, with complex failures cascading through the systems and shutting down flight control functions - God help any pilot faced with this scenario. Do all the rationalising and armchair deconstructions you wish, but being in the hot seat at that fateful moment is an entirely different matter.

Instrumentation error is less likely than stall
 

Jollin said
Quote:
Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?
"No, it is just as likely (or more so) to be an instrumentation error. "

This sentence is frightening : a pilot that doesn't believe his instruments because he doesn't believe he could have made a mistake is a fool, nearly dead.

Alway believe your instruments. An instrument IS more reliable than any pilot.

The A300 lost speed for less than one minute: all others instruments were available.

Touch'n'oops you are reading the little bus control laws. Big bus does have alt 1 & alt 2 & does not necessarily drop into direct law with gear down.
:=

JJFC - I refer you to my post (previous to yours) and point out that it proves your statment is WRONG.

I'll say no more than that.

For god sake!
 

Thousands of technicalities trying to explain the unexplicable:

- why BEA (and Air France, Airbus and ultimately the French Government) are hiding the whole CVR/FDR transcript? Why only this thin and very filtered information? What they are so affraid off? This is probably the most intriguing air disaster of the latest 50 years!

- why the pilots were unable to recognize a fully stalled aircraft and apply immediately corrective measures (valid for either a Cessna 152 or a B777, A330, ATR, you name it)? Only two explanations: a total lack of adequate training and basic airmanship or an A330 big design flaw that turns almost impossible to recover from a stall like this.

And then we'll be dealing with criminal negligence worth some billions of dollars.
THEY already know the truth and are scared about the consequences.:confused:

Instruments vs the pilot ?
 

@meccano

I said an instrument is MORE reliable than a pilot.

It is a very very confusing question :

Let's say :

- the instrument is 99.99% reliable.
- the pilot is 97% reliable

You have 0.01% chance that the instrument is wrong vs 3% the pilot is wrong.

All is a question of chance. Some pilots are more lucky than the others. It belongs to the pilot to cope with the 3% or the 0.01%.

I'm glad for you.

Sincerely your's.

One day in a Lear Jet descending out of FL410 I leaned over to balance the fuel with the FO hand flying, that was in the days you could fly by hand, and when I looked forward I notice our airspeed was approaching red line, my attitude indicator showed a right 30 degree bank and increasing and we were turning right. I cross checked the other two attitude indicators and they agreed so told my FO I have it and leveled the wiings in the clouds and it took every bit of concentration to not follow my instinct to go back to what felt level. I was actually leaning sideways to feel right but still trusted the instruments. In this case however the IAS was wrong and needed to be disregarded. Recent Airbus Pitot static problems with other flights would not let me trust the airspeed instruments in this case. I can't believe anybody would certify an airliner that is stalled but the stall warning mutes because the pitot static system senses less than 60 knots. That is nuts.

ST27 Quote:
The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so
I was exaggerating somewhat, since the previous poster had suggested a constant deceleration throughout the incident, and that the ride might have seemed like horizontal flight.

The BEA report states that the IAS near the top of the ballistic path was 185 kts (about mach .59), and suggested that this was an accurate speed, since the indications on two instruments coincided.

Some simple physics calculations can be made to confirm that, given that when the aircraft started the episode, it was flying in level flight and at constant speed. As a rough assumption, it can be assumed that the energy needed to climb 3,000 feet will all come by bleeding off the energy of the forward motion of the aircraft.

The calculation suggests that they would have lost about 260 kts as a result of the climb, ignoring the effect of the TOGA power that was applied for a while during the climb. That puts us pretty close to the 185 kts that was recorded. So overall, they would have dropped from mach .82 to about mach .59 in about 30 seconds.

Perceived vertical acceleration would have been something like +1.5g near the start of the climb, and +0.5 g over the top. That certainly would have been noticed by both passengers and crew.

JJFC
If you KNOW an instrument is faulty - are you seriously suggesting we follow it? I hope I'm misunderstanding you here, because any pilot is potentially 100% more reliable than a faulty instrument!
And unfortunately it's not always clear cut. Contradictory indications often occur.
Which instrument to believe then??

Then it is down to the skill and experience of the human at the controls, and he may have to utterly disregard the instrument right in front of him which is screaming for his attention. No easy feat, at the best of times.

Trapped frozen pitot tube pressure would give an overspeed zooming to 380 so probably explains the idle power. Once stalled descending at 11,000 ft per minute the ias would rapidly decrease as the static pressure increased. So at 60 knots ias the stall warning quits so the FO's think they have recovered from the stall are in a deep stall. What a system design. It took a lot of their final minutes comforted by false information. Hopefully the BEA will tell us more of what we know they have learned but their brief preliminary report leaving out so much data they have puzzled me. Maybe they have to run it by the French attorneys first.

Let's try and take this a piece at a time:

Beginning of the incident (first 11 seconds) -

"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 would expect pitot icing to be a gradual process. Why is there a "sharp fall" of 215 kts in IAS at this point?

I don't doubt the probes were iced, I'm just wondering how that alone would drop the indicated speed so rapidly. If the pitots are blocked, this is not a "real" speed change, correct?

If the pitots are blocked and trapping pressure, a climb should result in an increase in indicated speed as static pressure drops. Correct? (That is not apparently what happened).

If the pitots are blocked, a descent would result in a drop in indicated speed as static pressure increases. Correct?

TCAS Fail Unrelated to Other
 

TCAS depends on Range, Rate of Closure and Altitude Difference for Collision Avoidance, nothing more.

Range and Rate of Closure are determined by interrogating other aircraft's transponder. TCAS is like ground based ATC radar in that respect. Altitude Difference is found by subtracting other aircraft's reported altitude from own aircraft altitude.

TCAS receives Own Aircraft Altitude from the active ATC transponder, which in turn receives it from its associated Air Data Computer (ADR). This assures that the TCAS is calculating altitude difference from the same altitude that is transmitted to other aircraft TCAS.

Imperfect placement of the static ports on the side of the plane result in skewed static pressure at low airspeeds. The ADR corrects the static pressure based on airspeed when converting it to altitude for relay to the rest of the systems that use altitude.

The OZ A330 that had pitot icing in Aug 2009, indicated a sudden drop of 300 feet in measured altitude along with the airspeed decay to a low number, which is explained by the airspeed correction routine.

Why was the TCAS Fail reported on 447? BEA in their first release explained it was due to logic internal to the TCAS that would not accept the sudden drop in calculated altitude it was receiving.

Do you see the fallacy in that? If you don't want your TCAS working with bogus altitude, you sure don't want your ATC transponder working with it either. If there was such an altitude reasonableness check, it should be in the transponder, not the TCAS.

Maybe the TCAS Fail was like the Wiring Fail reported: the plane could have been getting the crap shaken out of it.

Cancel that last sentence. Found this from 16 April:

I don't know why the TCAS reported Fail, but I'm certain it was not due to pitot error.

.

But as I speculated in an earlier post, from the AVAILABLE data, it seems that that is precisely what they did. Would you agree?

Graybeard

"Maybe the TCAS Fail was like the Wiring Fail reported: the plane could have been getting the crap shaken out of it."

The autopilot dropped due to A) unreliable airspeed, B) exceeded control limits.

The a/p needn't be commanded to drop by the FMS (AD disagree). It will drop involuntarily all by itself if it cannot control the airplane, (within its limits). If it drops for this reason, Normal Law is retained with Stall protections and overbank protections. If for whatever reason the pitots inhale 30 knot disacrepant airflow, there we have AD disagree, though not ice caused, but turbulence caused. Now it drops to Alternate Law, but ostensibly for other than Unreliable Airspeed. If turbulence induced, one could argue it is not truly unreliable, but for 30 seconds some form of local upset in airflow has discreped the pitot tubes (perhaps both on the same side).

Any turbulence of this description can be sudden in onset. An updraft of 100 knots could be proposed, (Let's give it a radial component just to be mean). An argument could ensue whether its borders would be crisp enough to differentiate long enough between fuselage halves to cause UAS. Either way, there is an in and out (out and back in?) Law exchange that may have occurred. Musical protections? goddamitey, what a handful. (The radial component, from the left, would give it a left wing high result).

An updraft would give it a boost in lift, and a diminution of IAS. Enough of a drop in IAS to cause "UAS"?

IF AoA is AS and Vane reliant, a temporary boost in indicated AoA, reduction of IAS, and rising VS, does this fool the FCS? Was 447 in a transient and turbulence induced Phantom Upset? Something a hand flying pilot may have patiently sat through?

Autoflight into severe Turbulence? VIABLE?

... If the pitots are blocked, this is not a "real" speed change, correct?

Sorry, not correct. Pitot tube data is reality in regard to relative wind velocity flowing past the lifting surfaces. The pitot tubes provide the only indicated air speed data the flight instrumentation software and the pilots had, aside from seat of the pants feel and intuition.

If the pitots are blocked and trapping pressure, a climb should result in an increase in indicated speed as static pressure drops. Correct? (That is not apparently what happened).

Ice blocking or clogging pitot tubes is not likely to "trap" dynamic pressure, which is (1/2)*air density*(relative wind velocity)^2. Instead, ice clogging the tube will tend to shelter the pressure transducer from dynamic pressure. Less dynamic pressure = slower indicated airspeed.

Pitot-Static (Prandtl) Tube

So NO, a climb will not result in a increase in IAS in the pitot tube scenario you describe.

...

The transcript which has been released is probably incomplete, as a couple of commenters here have already pointed out. I'll bet those three pilots did a lot more talking on their way down.

Modern Elmo

"... If the pitots are blocked, this is not a "real" speed change, correct?

"Sorry, not correct. Pitot tube data is reality in regard to relative wind velocity flowing past the lifting surfaces. The pitot tubes provide the only indicated air speed data the flight instrumentation software and the pilots had, aside from seat of the pants feel and intuition. "

Excuse me?

Actually, I think they did have a chance to use pitch/power. The BEA report states that the aircraft was stalled for the last 3m30s of the flight. The autopilot/throttle kicked out ~4m30 seconds before the recording stopped and that minute between the auto-pilot/throttle leaving and the actual stall appears to be a pilot induced climb with no change in power settings = pilot induced stall.

Of course, once in the stall recovery is a different matter.

"... If the pitots are blocked, this is not a "real" speed change, correct?

Pitot tubes clogged with ice sure can result in a real change in indicated airspeed.

I posted elsewhere, but as you indicate, there will turn out to be a significant degree of unrecognised spatial disorientation in the accident, probably somatogravic with false sensation of pitch down leading to nose up command and stall.

Insufficent trust of remaining instrument indications , and the complexity and foibles of an overly complex avionic system that performs poorly at the edge of the envelope......

Modern Elmo, by "real" speed change I meant the actual speed of the plane, not what was indicated.

I.E. - did the aircraft actually "sharply" lose 215 kts of TAS (or whatever 215 kts IAS equates to at that altitude, in TAS), or was that indicated "sharp" change an artifact of the icing of the pitot and/or other things - not including the "real" speed.

Sorry if I was unclear.

Hi,

A little "OT" but interesting ...

Flight AF 447
Analysis of Air France’s crisis communications

By Hédi Hichri
Account Director
Fleishman-Hillard France, September 2009

http://www.multiupload.com/0G4RRWNBYS

What garbage.

I suspect that whatever BEA comes up with will be controversial. We can record what the plane does on the DFDR. We can record what the flight crew says on the CVR. But what we cannot record is WHY they did what they did, unless they say so explicitly, which rarely happens. There is no mind reading device; it doesn't exist. Correlation doesn't equal causation.

Because we cannot read their minds and know their motivations, we are left with being able to only judge the process and the result. The result we already know, and we labor under the burden of hindsight bias. So that just leaves the process. Did they follow their training? Were their actions up to professional standards? If the answer is yes, then the cause of the accident lies elsewhere.

Hi,

AF447… What We Now Know « Dark Matter
The Right Attitude « Dark Matter

French was the language being used. Anything in English must have been translated. Translating anything is risky and aviation talk is full of jargon, acronyms, and technical comments....in this case, very probably seasoned with fear. They probably haven't had the CVR for long enough to prepare a certified translation.

FDR data do well in French too and original CVR is just perfect ...

they`ve had the data from both for what? 30 days? and you all want it in the public domain? how about actually investigate first before pampering to the whims of forum hero`s.

we wont see the information for a while yet - this time nexr year most likely.

Der Spiegel raises pertinent points
 

This Der Spiegel article was posted earlier by someone else, but resulted in zero discussion: Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International

Several of the points raised in this article have not even been touched upon by this group - in particular the potentially detrimental role of the horizontal stabilizer and the questioned culpability (beyond human error) of EASA, Thales (pitot tubes) and potentially Airbus...


The Pitot Tubes and culpability of EASA?
As stated in the report (2h 10min 05sec) the autopilot and auto-thrust disengaged due to icing of the pitot tubes (manufactured by Thales - see below) which resulted in loss of speed readings.

Several comments have been made here claiming that the passengers wouldn't have noticed anything...(I wish it were true)