Regarding pitot freeze modes:
 

Syseng68k :ok:

Totally concur.

After looking at the design and mechanics of current pitot designs, I would be very surprised if the drain hole had actually blocked, since the hole itself is in the main body of the probe and likely to be well heated. The probe tip is obviously the most 'cooled' part of the assembly and therefore the most susceptible to icing.

safetypee, I do agree, that's why I am asking again and again : Why don't we have access to those data ?
They are only data, why are they so secretive and so partially presented and so, in such a confused manner ?

3D animation is available too ...

Garage Years

"Finally, there has been some speculation that the pitot issue bay have been drain blockage leading to an increase in airspeed indication... where is this imaginary event coming from? Does anyone here rationally think that the BEA would not mention this? "

BEA left out a great deal, though including some milestones in their report. I am unwinding the flight from THS NU 3 degrees, backwards, and find that a possibility exists for unreliably high ias. With aft fuel for trim, wouldn't the HS be expected to provide less NU force for a given cruise velocity? So I am merely pondering the existence of a need for augmented NU from HS. If ice crystal blockage, I am thinking the Drain would pack first, increasing Pressure in the Tube, which the AD would read as increased a/s? The events that are most important may appear to be sequenced in the BEA note, but they are loosely organized v/v Time points (From 2:10:05). So 275knots may have been the "start" of uas, but that may not mean that the actual peak airspeed was not higher? Having not included a great deal in their note, no one can then select such an early "read" from a later Report, and claim "manipulation". That is merely an extension of their evident desire not to give up "too Much".

Understandable, I think.

If not due to speed, why was the HS trimmed for that much NU? Or, is that a normal cruise Trim for the reported mach?

Hi,

Honestly I do not think the pitot had a fault
The pitot worked exactly as expected by their certification
They do not have a fault
They were used out of the domain of specifications and certification
It's exactly the same Airbus tell about their plane:
Our aircraft and systems worked as expected ..
The aircraft had no fault.
Of course if you go out of the certification specifications ... you can have some weird outcomes ....

jcjeant

"That's not seat TV screens installed in the Air France A330 ?
This in flight video system (info channel about the flight) was functioning or not"

I would have thought that in ALT2 the entertainment system would have been o/s.

GY, “The probe tip is obviously the most 'cooled' part of the assembly and therefore the most susceptible to icing.”
Not necessarily so for ice crystals. Some regulatory thoughts on probe icing.
The small ice crystals might either block the tube because of the density of an accumulation – jam up, or some crystals melt and act as the glue for others to adhere to – an ice or ice / water block.
Thus the coolest point of a probe may not be the most likely place for ice crystal icing; the crystals tend to bounce off a cool dry surface.
The mechanics of the icing also depend on the crystal size or mass, the airflow path before and in the probe, and the anti-ice heating capability - heat flow.

Bear:

You are assuming the THS trim was 3 degrees at the start of the incident, but that is NOT stated.

What we have is this:

So we have a pitch trim of +2.5 degrees @ 205t and 29%. Anyone know what the THS would be at for this configuration? These are the start conditions.

Following this we are told speed was reduced to 0.8M at 2h08m07.

At 2h10m05 the AP and then AT drop. We are then told PF made a left NU input... climb to FL375..

At 2h10m51 we are told TO/GA was demanded and PF maintained NU inputs. Only NOW is the THS mentioned: The THS passed from 3 to 13 degrees NU in about 1 minute...

Assuming (ouch) this note is in chronological order, the THS trim was at +3 degrees at 2h10m51 and THEN increased. We don't know what it was at 2h10m05.

Honestly, I find the ability to somehow reorder or overlook significant parts of the timeline frustrating. I realize we are all trying to make sense of what little data we do have, but much of what is being thrown out here is such a jumble of the details we ARE TOLD in the BEA note, that it becomes an exercise in futility.

Unfortunately I can only conclude that there is an attempt being made to fit the foot to the shoe and not the shoe to the foot.

Wrg:adiru1 bus adr1-2 to fcpc2
 

No doubt this is a wiring (WRG) problem, either internal in the PRIM2 or in the wiring from ADR1 ARINC BUS 1-2 from terminal to PRIM2 (includes, as JD-EE is correctly stated: the multi-connector). Wiring problems are rather easy to detect, send a test signal and compare with what is returned. It’s all day routine and takes place all the time, devices in control or in standby.
This is a class 2 maintenance message, no big deal if solely reported, it’s still receiving input data from ADR2 & 3
Trouble Shooting Manual is clear, replace FCPC2 = (PRIM2) and if fault persist check wiring from terminal to FCPC21]

Not easy to say in relation to the other problems. [B]“Need more data to compute!” e.g. what was crew-action on ECAM warnings, They should X-check speed and isolate ADR in error. Though job with 3 unreliable speeds but had to make a decision otherwise PRIM (in control) will make a decision which data to be used. BEA report doesn’t mention crew action on warnings neither which PRIM was in control. They only stated ADR 1 was rejected by PRIM in control.

Although only 1 PRIM is in control at a time, other PRIMS do X-check each other, if they disagree with output they will report (not mentioned in ACARS List) and probably transfer control to another consistent PRIM. PRIM 1 and SEC 1 messages most proberly be due to crew action, no correlated fault)

Could PRIM2 be in NORMAL LAW and others in ALTERNATE LAW, Very unlikely because ADR DISAGREE (due to PROBE PITOT 1+2,2+3,1+3) results in ALTERNATE LAW for all PRIMS.

And even when PRIM2 was in control and the only one in NORMAL LAW, ADR data is used for protection, IR/ accelerometers for feedback and control is by AP or SS both in NORMAL as in ALTERNATE.
Software or even program bugs? Very unlikely after all those years! few incidents where reported due to intermix of mod status ADIRUs and/or PRIMs, as far as I know never with disastrous outcome.

gums, 1842
You are right, air temperature is required, for accuracy. In the old days
of mechanical instruments, machmeters had only pitot and static input ports
and made assumptions about air temperature vs altitude. Non linear
cams and levers then translated that to mach dial reading, with the temp
parameter effectively factored in from the altitude capsule.

When air data computers arrived, it became much easier to plug the
temperature into the equation, as a synchro or pot input. The driver for
this being the need for much greater accuracy of measurement. Even
some of the earliest electromechanical adc's had tas and mach capability,
so not such a new idea....

Edit:

Went back to check and could not verify it. Referring to Collinson,
there's no mention of temperature in Mach calculations. You definately do
need temperature for true air speed calculation,, but can't confirm the
mach case. Perhaps someone else has more info ?...

safetypee:

Thanks for the link. Here's what I read:

Modes of failure:

safetypee, re # 1918: In an ADC, the temperature, (TAT or SAT) is used to compute TAS from the sound speed and Mach number.

WRG
 

A33Zab : thank you for this

Now this is very interesting :

Do you remember the timing for ADR DISAGREE in this accident sequence ? Time-stamp from CMC says 02:12 if I remember correctly. Can you tell us more about the difference between NAV ADR DISAGREE and F/CTL ADR DISAGREE ? Which system declares disagreement ?

I never said it was likely or probable in general, quite the contrary. I said it was likely in this instance.

How many successive software versions for the PRIMs ? Last time I checked, I thought I saw version number 19.

Again, this is a highly reliable and efficient aircraft. Its design philosophy has certain consequences, however. These consequences are not about safety, but about who can be deemed responsible for what.

Herr Professor Schmid wrote about this much better than I could :
Pilot or Computer in Command

Hi Svarin,

Thanks for that link to the very interesting document by Rechtsanwalt Prof. Dr. Ronald Schmid, Frankfurt am Main.

I agree with him completely. If Airbus FBW in ALT LAW doesn't have the same stall protection as Normal Law, then pilots should have the natural "elevator feel" returned to them, by disabling the auto trim function.

Tech forum
 

eSpoiler

As you will be able to read in the many posts this was considered and discussed in detail. The discussions are deep and here concentrated in all technical aspects of the tragedy.

"...You are assuming the THS trim was 3 degrees at the start of the incident, but that is NOT stated..."

Yes, I am, and no, it's not. BUT,

"...At 2h10m51 we are told TO/GA was demanded and PF maintained NU inputs. Only NOW is the THS mentioned: [B]The THS passed from 3 to 13 degrees NU in about 1 minute..."

I know you read it this way, (three degrees @ 2:10:51),

I read it:

"Three degrees at 2:10:51 LESS "About a minute". This makes the Three degrees time @ +/- 2:09:51.

Since we are entertaining a loss of airdata @ 2:10:05, and the PF immediately input NU, it is illogical to assume the THS only Started its Trimming excursion at @ 2:10:51. . . If not, I defer to your conclusion.

"The aircraft designer must therefore, if necessary, even dispense with technical ...("ADVANCES"**)... in order to ensure that the aircraft remains operable, comprehensible and thus controllable by the human being. Under no circumstances can technology be permitted to filter or block out information, much less take action on its own."

**Dispense with .....

How about unwinding a few prior? (existing "advances")

IMAO, The one basic and glaring error in the "Philosophy" of fbw as practiced by the folks @ Airbus, is the following:

NORMAL is Rules based, and these rules are explicit. Flying is situational, and the computer doesn't have the capability to program for all of them.

Especially when the rules are not immediately available to foster "Situational".

Some problems require a format that is as yet u/a in the world of cyber.

Thought, Both Abstract and Intuitive.

A belief is a conclusion based on data. Faith is a format based based on Intuition, and "feel". When my beliefs are dashed, I rely on my Faith, which is in me, and my F/O.

The Wall of misunderstanding twixt the engineer and the Pilot will keep killing people until both understand the other. Please stop stubborn Pride from putting people at risk.

Ecam view
 

In image below I tried to show you ECAM WARNING AREA as it would looked like.
(As far as warnings are known to the public!)
I did priortized them as if they occured at the same time.
Only 7 lines (boxed in image) are in direct view, the header only of warnings not in view are in the overflow area at the RH side.
If crew action is performed and warning is cleared this line is removed (transferred to Status page) and lines in ECAM Warning area scrolls up.
MW and Cautions and aural sounds appear in real time with 1 sec. interval.

Flightphase Cruise, in other flightphases ECAM crewactions might differ
If QRH is leading crew action * REFER TO QRH/OEB PROC * is shown.

Flags on FFD are not shown and svoice from STALL can occur at same time as warningssounds.
http://i474.photobucket.com/albums/r...9/ECAMList.jpg

WRG
 

Don't forget to mention connector, pins & s'u'ckets!

Flight Computer Data Concentrator 2 (FCDC2) aka EFCS2 is the detector for NAV ADR DISAGREE and declares ALT 2 LAW.
A F/CTL ADR DISAGREE msg doesn't exist, only NAV ADR DISAGREE.

From the report:

Why should the BEA release such materials prior to the publishing of a report when practically no other accident investigation bureau does? I don't see you lambasting the NTSB or AAIB for not releasing data until they're ready to!

You're proposing a design change based on a single incident. Don't you think these scenarios have been played out to determine the design parameters? I suspect that the reason trim remains a sidestick function in Alternative Law would be in the case of an incapacitated crew scenario, where the remaining pilot has elevator and trim in their stick hand and throttles in the other, rather than having to dance between the stick, throttles and trim wheel with only two hands. What you're in effect proposing is a straight drop to Direct Law upon loss of air data.

But bear, as yet there's no evidence of a "wall of misunderstanding" in this accident because we don't have all the facts, yet you and many others (barely any of whom are current Airbus pilots) are pronouncing it as if you have the facts in your hands rather than simply regurgitating prejudice.

Originally Posted by DozyWannabe
How do you cope with rudder trim?

For eSpoiler:
I hope this hasnt already been discussed

It has, since about as soon as the ACARS information became available to, (or was leaked to), the public. :cool:

Between the date of release and the day the FDR data began to become available, the ACARS data were dissected minutely on these forums ... three threads in the Tech Log forum, and two in the regular forum (or maybe one got moved to here). Happy reading. I've slogged through it all, over the past year and a half, and while there is a lot of noise, there is also some very useful signal.

Remember: ACARS is a system intended to inform the manitenance shop what things were going wrong while the plane was flying, so they can have repair or replace options ready when the aircraft arrives at the next maintenance facility. The more I learn about it, the more useful I think it is for the paying customers. Faster turn around times and fewer things not working between stops could be a benefit of this system ... except of course for things that require major repair.
As noted above, pounded into the pavement. I suggest to you that the BEA are using all of it, and comparing it to what else they know, have found out, or infer.

You are not alone. Most pilots are puzzled by that as well ... the search into "what happened?" has filled a whole lot of bandwidth, and many pages on these forums.

Doze

Hey. Re:

"...But bear, as yet there's no evidence of a "wall of misunderstanding" in this accident because we don't have all the facts, yet you and many others (barely any of whom are current Airbus pilots) are pronouncing it as if you have the facts in your hands rather than simply regurgitating prejudice..."

Hmmm. "...to 13 degrees nose up, and remained in that position to impact..." (reference the THS via BEA note to Public.)

Perhaps then just a minor mistake? Someone did not get the a/c that "did everything it was supposed to do".. I call that evidence of a "Wall". If PF did not take note of the "THS MAN PITCH ONLY", I like to think that is a major misunderstanding. Why does the a/c "TRIM" outside NORMAL LAW?
Seems if the a/c was in need of emphatic inputs, perhaps "quickly needed" and in opposition to eachother, why invogorate a system that s l o w l y reacts with a gargantuan control surface, with immense authority, and likely to get in the way of assertive handling?

just a thought

Why would you be using rudder in cruise? Rudder is a different system anyway, and as I understand it is the most conventional aspect of FBW Airbus design.

@bearfoil : You've got no evidence for that assertion. You don't know, I don't know - none of us know what happened in that flight deck for those few minutes. We don't know whether the PF was confused by what he saw, we don't know if he panic-pulled (as has been known to happen) and we don't know if he did it because the little devil on his shoulder told him to. If you've got evidence that the pilot was confused by the law reversion then present it, otherwise you're just blowing hot air.

Lonewolf

"...Remember: ACARS is a system intended to inform the manitenance shop what things were going wrong while the plane was flying, so they can have repair or replace options ready when the aircraft arrives at the next maintenance facility. The more I learn about it, the more useful I think it is for the paying customers. Faster turn around times and fewer things not working between stops could be a benefit of this system ... except of course for things that require major repair..."

Let's say I troubleshoot my aircraft aloft, and radio to Leo that xxx needs replacement, and I have two hours to layover on my way to Vegas. Leo says "Roj, bear, no big."

I own a GV and Leo pays his mortgage and buys a Corvette each year on 'my' dime. Pressure? uh, yep. Same with the Line, only worse. If I'm late, Leo deals with me, and he knows I will understand. On the ramp, Charlie has a poor record "keeping up" with Mx demands, because he is "old fashioned".

219 pax, a crew of twelve, all with Plans, and some are not so nice. ACARS is useful, but it is only a tool. Have you ever tried to show a beancounter how to use a tool?

bear

Dozy What I posted was evidence, from no less than BEA. You reply with three degrading possibilities for PF? Anything in your quiver that at least gives our Friend David a chance at saving his reputation? Because I know in my bones you think TRIMMING two barn doors is a good idea when you are about to die.

I’m afraid the incapacitated crew scenario would be a rather weak justification for keeping auto-trim in ALT law. MS FS players all have joysticks with “Hat switches” that can be used to change trim. I would be surprised if military pilots ever used a trim wheel on their fbw jets.

rudderrudderrat - The important lesson to pull from the math is that the mass makes no difference in the physics class model.
Speaking of math - how does Mach .82 become something under 300 knots IAS when literature I can find suggests Mach 1 is over 580 knots? (585 knots at FL290 is the number from Wikipedia with an increase with altitude indicated by the three data points given.) I guess no effort is made to translate pitot tube indicated speed into a true speed through the air? Will this have to happen when laser speed measurement becomes practical?

Trim is useless in upset. If fast enough to matter, it would be dangerous, and if slow enough to be safe, it is useless. And that's only if it stays put at 0 degrees.

More like "if you go out of the certification specifications ... you can have no weird outcomes"

Safety critical systems are designed to perform well beyond the certification specifications (as we now know from the survival of DFDR/CVR). Even in extreme cases like partial shutdown/reboot of systems, I'd bet Airbus fully understands the behavior of the system.

To the extent that Airbus thinks the a/c systems did not misbehave probably means that there are not going to be any surprises in future BEA reports.

Having said that, my reaction to A33Zab's image of Ecam view was: Yuck

henra - remember I am a cynic when politics, lawyers, or marketing is involved.
I would invite you to make a case for any of the other involved people making the release with precisely the data given and no other data. It looks like the data benefits AirBus, is neutral to or damages Air France, and smears the pilots' reputations. It might have been the French government. Blaming the pilots gets them off a financial hook to some degree. Who else benefits?

Its the speed that would give same dynamic pressure at standard air density (sea level) - useful because its basically what the wings use to generate lift, independent of altitude Its also basically what pitot tubes measure - think simple analogue dial without all the digital compensations! See also the definition of Flight Level FL and its link to real altitude in ft.

Are You A Pilot?
 

Dozy: Dozy, are you a pilot?

Incorrect. All I've said is that we don't know. I don't give a stuff about reputations (either corporate or personal), I want to stick to the facts, or at least to give everyone a fair hearing. The only way autotrim is activated is if the stick is fully deflected and held there past the elevator travel limit. It's there to give the pilot more authority when the chips are down. If your friend David wasn't aware of that then it was a failure in his training, not his piloting.

@DJ77. Doesn't sound that weak to me. If you've got full authority over the aircraft with both your hands on the primary flight controls then surely with the correct training it's an improvement? Just because cockpit ergonomics remained fairly static from the 1940s to 1988 doesn't mean that it's the "right" way to do it...

@Smilin_Ed - you should know I'm not (the clue's in the handle), nor have I ever pretended to be. You've got to understand that I'm not slamming the pilot because I don't have the evidence to do so (nor am I the kind of person who would even if I did). I'm just a little fed up with some on here bashing the aircraft and systems design when they don't have any evidence either.

GY, I am sure the substance of the BEA release is accurate as stated.

The cynic in me suggests it was to satisfy AirBus as AirBus leaked ever more data. It was finely crafted to really show only that the aircraft did exactly what the pilots told it to do. I can't see anything else the data shows conclusively. And it seems to have shut up the leak, AirBus or not AirBus.

I am sure the final report will show more than what the release shows. Do the aerodynamics of the aircraft support the altitude gain with a specific wind direction or still air? Does that shed light on anything in the cockpit? Was the data presented to the pilots sufficient for them to diagnose the situation in the face of a possible fixation on UAS procedures? Are there software improvements indicated? Are there flight display improvements indicated? Did Air France order a suitable set of options for the flight display? Are there hardware improvements indicated? Are there training improvements indicated?

These and more all must be answered in any final report. Some of it may end up showing AirBus in a bad light based on the total data set and serious aerodynamic modeling. And even if it shows AirBus in a bad light I suspect it will not contradict what was released. It will simply explain what was released.

The people here, mostly far more expert than I am, are discovering that the data shown reveals very little that can lead to a solid conclusion because we lack some of the data and the fine grain data from the recorder and the aircraft test and modeling efforts that the BEA no doubt has today. The important thing is that even as sloppy as this data may be - it shut up the leaks.

(And it gave us something to discuss here. I sure hope the final report addresses some of the issues we've found here well enough to satisfy us. We have found some potential issues in hardware, software, training, and design it seems. And one or more of these issues may still be unsolvable within the current state of the art.)

Dozy

"...@DJ77. Doesn't sound that weak to me. If you've got full authority over the aircraft with both your hands on the primary flight controls then surely with the correct training it's an improvement? Just because cockpit ergonomics remained fairly static from the 1940s to 1988 doesn't mean that it's the "right" way to do it..."

Let me ask another way. Do you have full control of the aircraft with both hands and THS trimmed NU 13 degrees?

NO. Unless you have a third hand. The last thing anyone wants when trying to RECOVER, is an aircraft that is destabilized by something trying to HELP, that then quits

Again there's no evidence for what you're asserting. Unless something went spectacularly wrong the only way the THS went up 13 degrees was because the PF put it there. Did something go spectacularly wrong with the systems or did the PF actually deliberately pull on the stick to get it into that position? Did he know that he could wind the trim forward with the wheel to remedy the situation? We don't know -which is why I want to wait until we know what happened before we start talking about changing features of the systems and aircraft design.

sensor_validation and JD-EE,
What's the argument?
ISA speed of sound at the altitude in question is in the order of 580 kts.
Mach 0.82 x 580 kts = 475 kts TAS
Do your sums for IAS.

bear, the nice thing about the ACARS is that a lot of trouble shooting can be set up that you can't trouble shoot or check for in the air. I spent a LOT of years writing up "gripes" in the maintenance office, describing what I was seeing in flight that was wrong. As time went on, I learned how to write a better gripe, and how to do a little trouble shooting, time permitting, before I landed, so I can give the mechanic more info when he enters his trouble shooting tree.

I see ACARS (in its role as maintenance and operations asset) as speeding up that process. If the pilot can add info, I am sure most companies call for them to do so, by voice, as you suggest you would do, and as I did for years.

"Chief, this is 231, we've got the fuel in manual trim. Looks like the normal actuator crapped out again ... " ah, the GE T-58, lovely kit. :cool:

You can play with this (scroll down - there's a nice Mach/CAS/TAS calculator):

Aviation Calculator

0.82M = 279knots CAS @ FL350

Do You Have A Dog In This Fight?
 

Dozy, if you were a pilot you would understand why I, and some other pilots, don't want the trim to change by itself when we are trying to fly the airplane by hand. Due to reasons which are not yet clear to us on PPRuNE, the flight control system was not fully functional and it turned things over to the pilots, but not fully. Because of what may have been an inadvertent nose-up input to the side stick, the trim went full up and the airplane was trimmed into a stall from which the pilots were not able to recover.

When practicing stalls, student pilots are warned NOT to trim into the stall. := That is so when they let go of the stick, the airplane will return to a trimmed speed which is BELOW the stall speed. Further, if you trim into the stall, the trim might not move fast enough to get you out when you need it to. I suspect that these guys were blindsided by the autotrim.

Next question: Were you involved in the design of the FBW system under discussion?

JD

IIRC from my wiz wheel days ...

Indicated to (check the card/chart in the aircraft) Calibrated to (adjust for temp and altitude (air density) True. IIRC, the Higher you go, the more True you get for a given Indicated/Calibrated (those tend to be close).

You then vector sum your wind component with your velocity (a vector) (True Airspeed & heading) to get your Ground speed and Track. (Another vector, a resultant IIRC).

GPS uses expensive gremlins to do all that. :}

Cheers.