bubbers44

The way this thread is going we desperately need the final report to get back on the track. Why won't they give it to us?

3holelover

What is the expected result from a gradual blockage of the drain hole alone?

bubbers44

PJ2, yes, if they had maintained level flight they wouldn't have gotten an overspeed, but if he climbed for whatever his reason with trapped pitot pressure and reducing static pressure he may have gotten an overspeed warning that caused him to pull up into a stall. Normally a pilot wouldn't do that but for some reason he did. Unfortunately the captain wasn't there at the time to prevent it, if that is what happened. I hope they don't drag their feet on releasing the FDR and CVR reports because this could happen again if they sit on it. The aircraft they were flying was already known to have faulty pitot tubes but hadn't been changed yet when this accident happened.

A33Zab

RR_NDB:
RT? Why not make the demand: PREDICTIVE!

I already mentioned before and is repeated by others:

They (FCPCs) know when the speed is missing, they don't know the probes iced up. That will be the task for CMC to correlate warning with failure.

How critical is a Pitot probe icing? not a red alert - immediate action required - in view of the A/C industry in general.

UAS caused by Pitot Icing = Transient.

"Whenever unreliable airspeed indication is suspected and aircraft attitudeand thrust are not consistent with the flight phase, initially disregard all speed indications and use pitch attitude and thrust setting as primary flight references." Like NW did and the other incidents.......

Note: the statement above is NOT from airbus.


Question to all.

Considering the ECAM messages, after clearing the A/P disconnect the first CREW action will be:
-THR LEVERS……..MOVE

@RR_NDB: presented In RT (repeat interval 5 sec., must be important)
Timestamped 02:10:06

They know from heart T/L need to be moved towards 'frozen' N1.

45 sec. passed.

BEA states: 02:10:51 ....The thrust levers were positioned in the TO/GA detent and.....
In what postion was it in between? What is the expected cruise N1 with data just before the event at 2::10:04?

PJ2

bubbers44;
Yes I know. I make that observation in my post. I've had this occur in a B767 and that is precisely what happened...the airspeed increased beyond the VMO, (didn't get the Overspeed warning though) but in our case we ignored it because we had the standby AS to help us guess which one had the correct reading.

My point in this part of the argument is that the speed increase in a thousand foot increase at the beginning of the pitch-up isn't dramatic...it isn't in the order of "50kts", say...and it isn't much more in a 3000ft increase...it isn't large enough to warrant a pitch > 10deg to reduce speed.

3holelover;
It depends upon whether the tube downstream of the drain hole is also plugged due rain unable to drain fast enough from the pitot tube. If the tube is blocked, the effect is the same as if both the tube and the drain hole is blocked and the airspeed would drop. If the blockage was due to water (flight through heavy rain), the speed could fluctate between actual and lower indications and would do so in relation to the changing amount of blockage. If the drain hole itself is plugged but the tube itself is clear, then I think that there is no effect on the sensed total pressure and the airspeed would be accurate.

All this is largely from the A300-600 FCOM information on "Abnormal Procedures - PITOT PROBE DESIGN, (posted by Chris Scott or gums which I can no longer find on the previous threads) - Thank you Chris for finding Tubby Linton's post.

PJ2

A33Zab;
Thrust Lock would keep the thrust at the cruise setting existing just prior to the UAS event. In response to the "THR LEVERS....MOVE" message, the thrust levers would be moved out of the CLB detent and set to the N1 existing just prior to the event. That would be just below the MCL detent (slightly less than 30deg TLA), probably around 84% N1.

RR_NDB

A33ZabYes, Real Time! Itīs technically possible today*!

PREDICTIVE, unfortunately itīs not possible, as we all know.

Please, see Causality, here.

May be in the future an special Radar (or Laser?) could anticipate probable conditions to (sub heated sensors) Pitot icing degradation.

bubbers44

They were cruising at M .80 at FL350 so how much static pressure change with a climb would it take to go above mach limit with a blocked pitot tube? I don't know but am trying to understand why they pulled up into a deep stall.
Something must have spooked them. I don't think just losing AS would. Maybe the stall warning going off again at the latter part of their descent and pulling back into a deep stall to silence it also caused them to pull up into a stall as the overspeed warning sounded. The guy flying was pretty new on the aircraft.

Chris Scott

PJ2, quote:
All this is largely from the A300-600 FCOM information on "Abnormal Procedures - PITOT PROBE DESIGN, (posted by Chris Scott or gums which I can no longer find on the previous threads)

Not guilty, m'lud... Is this what you are looking for?

http://www.pprune.org/tech-log/44963...ml#post6442305

See also tubby's next post.

Re ASI 2, I hope the BEA will let us know about the QAR in their next report.
Good night!

RR_NDB

Hi,

PJ2Indeed, so far, a mystery.

On the recording (video never) i will elaborate in next post. The idea is:

We probably should (for the investigation) to record some "internal parameters" of the System. AFAIK FDR is not for that. The current "recording" doesnīt take into account certain important "internal mechanisms" probably important for a better (impartial) analysis from the investigation branches. I donīt like the idea to be dependent on the plane manufacturer for some more complex details during the investigation analysis. The complexity of the "advanced planes" it seems correlated to "Mooreīs law"

CONF iture

For 45 seconds, thrust could have been anywhere between idle and climb thrust. It all depends on what was trying to achieve the A/THR at the time of disconnect. Was it trying to reduce the speed, was it chasing the M 0.80, was it just set to the proper EPR to maintain the requested selected Mach ...
BEA knows ...

Additional thought : For close to 3 minutes, the Captain, a guy with experience, was in the flight deck ...
What were his comments ?
Any Directives ... !?
He didn't come back to just shut up ... did he ?

BEA ...

jcjeant

Hi,

PJ2 wrote (and many others)
It's no failure with the Pitot tubes
They worked as expected (it's not a failure of the Pitot tubes .. it's a use of the Pitot tubes outside the limits [domain] of their certification)

PJ2

Sorry RR_NDB but I'm not understanding what your saying.What do you mean by "internal mechanisms"? I've never heard of the term in accident investigation or flight data analysis work.

Also, what makes you say that an investigation is, "dependent upon the plane manufacturer for some complex details during the investigation analysis." What does that mean? What are you trying to say? What, specifically, are these "complex details" to which you refer? What do you mean by "advanced planes"?

You claim a connection with "Moores Law", but you don't explain the connection and just leave your readers guessing. I looked it up using your link. There's no connection to AF 447 or flight data work whatsoever.

If you're advancing some kind of notion that this is all a conspiracy on the part of manufacturers to suppress or even hide information from the investigators then I don't think you know very much about aviation, flight safety work, accident investigation or flight data analysis and the way it all works together.

So....is it your thesis that, "manufacturer's making it difficult for investigators by controlling all the parameters on the FDR so we only get to see what they want us to see"?

PJ2

Hello Chris, yes, thank you, that's what I was trying to find. Searching for an image isn't possible and the PPRuNe search engine doesn't work well for me in IE8, tho' it could be the operator - I should have recalled that it was tubby linton's. I thought it was good info - I have nothing like it in any of my (Airbus) FCOMs.

PJ2

bubbers44;
We don't know yet who was flying the aircraft. There have been good arguments for either scenario. Hopefully that information will be in the next BEA report when it comes out.

- I would like to know more about the Relief Pilot position at AF.

- On initial training is the RP given a full endorsement on the airplane?

- Is the endorsement maintained or is it intentionally allowed to lapse because the RP can legally only occupy the front seats in cruise?

- Does the RP get to takeoff and land the aircraft or is the RP position strictly Cruise Altitude? If not, how does the RP gain handling experience, if at all? (One can have several thousand hours on an airplane and actually never even fly it let alone handle it in circumstances faced by the crew of AF 447.)

- Can the RP occupy the Left Seat to replace the captain or, due to licensing legalities, must the First Officer sit in the left seat? And if so, what kind of recurrent training does the F/O receive?

- If the F/O occupies the left seat, does this apply "in Cruise Only" or is s/he allowed to takeoff and land from the LS?

- If the F/O does indeed replace the captain, is there some concern regarding the switching of seat positions in terms of familiarity, comfort, and trained, automatic reactions. (I think most here who do this work and perhaps instruct would agree that although one gets used to it, there IS a distinct difference when flying from a seat that is not normally one's own - it isn't nearly as comfortable, in other words.)

There are a number of other questions, but all this will come out sooner or later. I am hoping that the next BEA report addresses some of these basic human factors questions as part of the research supporting the final report.

Machinbird

OK465
That was a nice discussion about rolling your swept wing bird with rudder. Every swept wing tactical aircraft I flew rolled nicely at high AOA with rudder. It was considered the nature of the beasties and was essential to obtaining max maneuvering performance. You could even hold the aircraft in a stall and pick up the low wing with rudder when one wanted to drop. The wing drops became progressively more abrupt, however, so there was a limit to how long you would want to do that.

I have inadvertently overstated wing leveling ability with regard to Alt 1 Law (and Normal Law). I was intending to infer ability of the system to keep the shiny side up.

Per FCOM FLIGHT CONTROLS
Of course the system is not a wing leveling system, it is an attitude holding system, until you get into Alt 2 law. Then the wing attitude in roll becomes the sum of pilot inputs, environmental inputs, and lateral imbalance/rudder mistrim inputs. In Alt 2 law, the pilot must control the wings. No hands off is possible unless the aircraft is in perfect trim and the air is smooth.

RR_NDB

My objective now is to clarify to allow a perfect understanding of what i said (briefly in a short text). As i told you i will elaborate later.

I will start from your last phrase, a question:

Not! absolutely NOT!

Not! absolutely NOT!

I suspect a Safety Board could not be able to analyze some details (e.g. glitches) that may occur (and perhaps occurred) in this case. Svarin raised and elaborated on that. We may never be able to understand what happened because the required information could vanished (like the AS not measured). The complexity (State of the Art machines) of the Airbus SAS "advanced planes" may suggest a future rethink of the FDR concept. Why? Because when Airbus SAS advanced planes introduced FBW plus a new "control" philosophy (Laws, protections, etc.) put another "crew member" in the cockpit" and itīs behavior has to be fully analyzed (and understood) in an accident. This "complex crew member" was "flying" the a/c before AP/AT disengagement. And was also flying after (THS moved). And this "crew member" is "made" of Hardware, Software, internal links (subject to WRG failures, etc.) and is naturally subject to do unpredictable things. Despite itīs State of the Art characteristics. (Redundant, etc.) We can remember the (extreme) Reaganīs SDI Testability issue. And IIRC was you that posted an excellent text on "possible" and "probable" things.

The growing complexity of the "on board Systems" makes me remember the "Mooreī s Law" (named after Intel co-founder Gordon E. Moore, who described the trend in his 1965 paper.) I just made an analogy to the "prophecy", Intel Guruīs made that i observed closely all these years since i designed my first computer in 1975 using the first microprocessor, the Intel 4004 using itīs chipset. You may observe i put in the end of my phrase: to say you i was commenting with a "nerdīs humour". And the growing complexity concerns me. Why? Because i worked in complex Electronic Systems Design (in Test and Measurement area) dealing with Testability, Diagnosability and System Testing, Module Testing and Components Testing. In AF447 analysis we never will know the actual AS during certain moments, simply because this info. was not measured. And this occurred not by Pitot failure. As jcjeant told you. Other(s) System failure(s) (with the PF inside the loop) may never be possible to understand. Why? Because the mentioned "internal mechanisms" were not recorded. Complexity brings fantastic features, at a price. Observe iīm not saying what (if) occurred. We actually know very little. My objective now, as you well said, is to understand the "persistent pitch up". And iīm just remembering the complexity of the required analysis to allow a full understanding of a complex System like the ones being gradually put in the entire Aviation Industry with the leadership of Airbus SAS (paying the toll on the pioneers)

The current FDR concept deals with this "crew member" considering it as an Engineering black box. This point, as i told before, i will elaborate later.

(must awake early for a monday with some CBīs ahead I tried here to do my best to clarify, preparing what i will present later on the issue.

Finally i must mention the title of my post: Why the "pitch up"

The motivation to write "briefly in a short text" was only related to the most important (before July end) as you emphasized perfectly.

I am entirely open to further clarify to you or (anyone) any point before going deeper into the "probable need for more data" to fully "understand" the behavior of the "complex crew member" in an investigation of accidents involving "advanced planes"

PJ2

RR_NDB;

Ah, thank you, now I do understand much better what you meant. Will respond more fully shortly.

takata

Quite simply, there is no "Relief Pilot" slot in AF crews : the two F/Os should be fully qualified for all phases. F/Os were flying from Right seat at the time of AF447... but after that point it changed and Left seat training was also implemeted for F/Os.

More likely above 95% N1 depending on ISA.
I'll post later the tables for cruise at Mach 0.80 & 0.82 @ ISA +10, +15, +20.

takata

Cruise Tables for GE engines: