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AF447

Old 9th Jun 2009, 03:57
  #781 (permalink)  
 
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The F/CTL computers will report faults if they get enough bad air data info
Been through the FCOM3, and no where does it indicates that an ADR failure (or all of them for that matter) would fail the PRIMs or SECs?

They do receive information from they ADRs, but as the the fault was recognised by the PRIM, (the ADR DISAGREE fault was announced, indicating only two ADR were being used by the PRIMs and these ADR disagreed), ALT LAW would be latch and it would appear to be the end of it. Would you care to explain a bit more?
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Old 9th Jun 2009, 03:57
  #782 (permalink)  
 
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Originally Posted by philpop
CC,

In this scenario, how would you explain that radio was not used for MAYDAY
Aviate

Navigate

Communicate

Are the priorities.

Last edited by Lightning6; 9th Jun 2009 at 04:09.
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Old 9th Jun 2009, 04:10
  #783 (permalink)  
 
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grizzled

I didn't get the impression that either dani's post or lomapaseo's were referring directly to you or your posts. In dani's case he wasn't at all swatting at flies; he was making (what I thought at least) was an accurate and appropriate comment re some of the speculation of the past day. It seems to me that Lompaseo was doing the same thing.

Grizzled
Thanks for that.

Typically if I intend to counter a single post idea I will quote it. If I intend to offer a rebuttal directly to a person's individual opinion then I will include their name to avoid any other attribution.

PJ2 posts are quite capable of standing on their own and eloquently expressed. I might be adding my own tint of color from time to time on the subject just to broaden the readers outlook
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Old 9th Jun 2009, 04:11
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All my posts regarding a theory where an exploding oxy bottle (located in the avionics compartment, where all the computers are located, and very near all the probes as well) would be the root cause of the accident (QF had an oxy bottle explode a few months ago, resulting in a huge hole in the fuselage) have been deleted!! Even the post where I ask what happened with my previous posts has been removed.

Is this thread being censored?
Yes. Posts which speculate on causes not backed up by the facts are being deleted by the moderators, I believe.

There is no reason to suppose any such explosion. There was no explosive decompression indicated.
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Old 9th Jun 2009, 04:15
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CC,

In this scenario, how would you explain that radio was not used for MAYDAY
Good Question Philpop,

Since you asked respectfully, unlike Christy, I'll answer.

It takes a good number of seconds via any means to get a message off, no matter is it's HF, (high freq), ACARs (even longer) or even VHF on guard.

If the chit hits the fan, and you start fooling around looking for your hand-mike, screaming for people thousands of miles away to help you, then you will die. This wasn't a small thing that happened (Full Pinball TILT). The automation went haywire. The train came off the track. If you start spinning sideways in your car and decide right then, that you need to call for help on your CB..... guess what? Better hope that Channel 16 is the Coroner!

The first thing you must do, at all costs, is Hand Fly the Machine, while the other guy (let's hope he wasn't in the head) gets the train back on the track by restoring Air Data that the autopilot will accept. If you waste even a few seconds scratching your head at 500mph, it's adios controlled flight!

But these poor guys had 3-4 minutes of shear terror to deal with. And it's clear they never got back under control.

Aviate (get it under control, using hand flying and partial panel skills not taught anymore)

Navigate (radar cell avoidance)

and lastly, if you don't have enough to do already with the HAL-9000 going "DingDingDingDingDing"

Communicate.

CC

(see? It's not the Bermuda Triangle out there. It's over-reliance on automation imho.)

Last edited by Captain-Crunch; 9th Jun 2009 at 04:54. Reason: omitted nuts, cleaned it up
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Old 9th Jun 2009, 04:21
  #786 (permalink)  
 
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Originally Posted by bobrun
Been through the FCOM3, and no where does it indicates that an ADR failure (or all of them for that matter) would fail the PRIMs or SECs?

They do receive information from they ADRs, but as the the fault was recognised by the PRIM, (the ADR DISAGREE fault was announced, indicating only two ADR were being used by the PRIMs and these ADR disagreed), ALT LAW would be latch and it would appear to be the end of it. Would you care to explain a bit more?
Perhaps the IR2 FLR immediately before the two F/CTL warnings in the ACARS list?
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Old 9th Jun 2009, 05:11
  #787 (permalink)  
 
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No ACARS messages were received after 0214, suggesting a catastrophic airframe failure shortly thereafter. The vertical stabilizer probably sheared off then, either causing the loss of control and break-up, or, more likely, as a consequence of detrimental airloads during departure from normal flight.
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Old 9th Jun 2009, 05:14
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Airspeed calculation and indication depends on valid altitude calculation. Altitude calculation does not need airspeed, except for fine trimming. If icing the pitot tubes clogged them up, there is no logical reason to kill their companion static data outputs, as appears to have happened with this plane. It would seem to take a lot more icing to clog the static ports at the same time.

The Air Data boxes must have condemned the validity of their altitude outputs as well as airspeed, or the TCAS would not have flagged failed. TCAS does not have an airspeed input. Hence, if the "Pitot tubes are defective" is true, the Air Data boxes are also lacking necessary partitioning in their outputs.

By design, faulty airspeed computation/indication should not affect altitude computation/indication.

If clogged pitot were a not so rare phenomenon, altitude, attitude and ground speed would be used to simulate airspeed, using the last valid airspeed as baseline. But more than one pitot failing at a time is "too rare to consider."

GB
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Old 9th Jun 2009, 05:18
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Just because they have found the fin doesn't make it the prime suspect. There is nothing that indicates when it detached and very little to suggest why.
The speculators are out in force today. We had hot air bubbles 2 days ago and it's airbus composit material failure today. If they find an engine next are we going to blame that?
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Old 9th Jun 2009, 05:35
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FEHOppy,

You should actually read what I posted, I suggested that the state of the vertical stabiliser was the evidence, it did not appear to have been subjected to the extremely destructive forces of impact, suggesting it seperated in flight.

The radar system they are using to discover these components is a very sensitive one. Visual range of the MK1 eyeball is very limited. These large pieces are most likely being discovered by radar. This suggests that is is unlikely they will find anything larger. I know these facts from my experience as a naval air controller, none of it is speculation.

If you wish to make non-constructive comments and wait for the final report I suggest you don't post.
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Old 9th Jun 2009, 05:42
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The fact is, we know from previous experience and from Airbus admission that the fin is very sensitive to excessive sideloads.
In very extreme turbulence or in a loss of control situation, it is not unreasonable to expect such high loads on the vertical stabilizer.
It will be important to find out if the possible loss of the fin at altitude contributed to the accident or not.
Of course it could have remained attached until the airframe plunged in the water, but I find that option less likely. Time will tell.
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Old 9th Jun 2009, 05:50
  #792 (permalink)  
 
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In this scenario, how would you explain that radio was not used for MAYDAY
Human nature is at play here also. Whether it be as CC said, crew working too hard to make a call, or mind closing down by the reality of imminent death, I don't know, but aircraft have crashed with what seemed like ample time for the crew to holler something on the radio, but they did not. There's been grunts and groans on CVRs, but not much on the radio.
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Old 9th Jun 2009, 05:53
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ACARS only transmits what it is told. It has no influence on any warning messages at all and acars does not time stamp them.

CFDS sends messages to ACARS for transmitting. CFDS also logs any ECAM warning without filtering. So for the real pilots out there can you now answer the following questions:

I have just tripped the A330 autopilot manually to off. Do I get a warning?
If yes acars will transmit it, if no acars cant transmit nothing?

Hopefully that has cleared up that one.
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Old 9th Jun 2009, 05:53
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Would the yaw damper remain operational following the air data disagreements?

IOW -- would it auto-disengage along with the AP and the downgrade to Alternate Law?
@Zeffy - there are reversion modes even in Alternate law where some yaw damping functions are retained. Also, even with a loss of ATT data from the ADIRUs, there are dedicated gyros to assist with yaw control on the A330.
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Old 9th Jun 2009, 05:59
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@Safety Concerns:

I had earlier wondered the same thing when deciphering the ACARS messages and had been told (by an amused old fellow) and posted my answer earlier: An autopilot being switched off in the cockpit is nothing the Airbus CMS (Boeing acronym, sorry) will report home about.

To make it even clearer, logging and reporting to home base are two different functions and I have been told the choices of maintenance data sent can be airline-specific customizations.
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Old 9th Jun 2009, 06:06
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Interesting 2008 BEA report on turbulence

A remarkable website of BEA, the French bureau of investigation and analysis for the safety of civil aviation.
No sign of a report on the alleged collision of F-GZCP with another airbus in late 2006, but they do have a report on a similar incident in 2002 between two Italian Airbuses 330 clipping each others wings on French territory. Mmm….
Anyhow, I came across another interesting BEA publication from August 2008, a fully fledged study on “turbulence and air transport”. In French only of course, but never mind. For those who like me want to have go at it, here is the link:
[URL="http://www.bea.aero/etudes/turbulences.en.transport.aerien/turbulences.en.transport.aerien.pdf"]http://www.bea.aero/etudes/turbulences.en.transport.aerien/turbulences.en.transport.aerien.pdf URL]
The 34 pages of the report give a fresh reminder of the treacherous aspects of convective cells naturally also covered in the current pprune thread. The report takes 48 occurrences between 1995 and 2007 with French registered, exploited or produced aircraft in France or abroad as a basis for study. Much more than half of the accidents and incidents have occurred in or next to Cumulonimbus, in which circumstances also the most seriously wounded were registered.
Despite a good flight preparation which includes in many cases an awareness of adverse weather conditions en route, it is stated that many pilots are nonetheless very surprised when they are actually confronted with turbulence. In particular for long distance flights the report points to the aids available to flight crews to stay alert and informed about actual and developing weather conditions en route. The on board weather radar is mentioned in terms of its vital importance, but also the challenges and even shortcomings of its optimal use. And more interesting and useful stuff.One final thing I would like to highlight has to do with the recurrent discussions in this thread about the supposed message that the AF 447 crew sent by ACARS to inform their company that they were experiencing severe turbulence. The report mentions explicitly that some French airline companies, in particular those that fly long distance routes, have dedicated departments that communicate via ACARS on updated weather situations en route. Where those departments are then specifically tasked with providing specific updates on weather to flightcrews. I would be surprised if AF would not have such a dedicated department. In that light an ACARS based exchange sounds very plausible. One of the questions in the AF447 case would then be why it was the pilot informing the dedicated department of the severe weather when they were experiencing it, and not the other way around so that avoiding action could have been taken.
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Old 9th Jun 2009, 06:07
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Wytnucls, you mean that it's not overbuilt ? Not surprising since it "only" needs to be up to spec.. I don't get your point.
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Old 9th Jun 2009, 06:17
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AIT-Dispatch, AIRBUS

FYI.

Please, be patient.

At this stage of the investigation, there are no new available data
than the messages which have been transmitted automatically from the
aircraft to the airline maintenance center.

The above mentioned messages indicate that there was unreliable
airspeed indication. This unreliable airspeed situation is consolidated
by several messages which show system reconfigurations which are per-
design consequences of the unreliable airspeed indication.

The last transmitted message corresponds to the ECAM Advisory message
indicating a change of cabin altitude at a rate greater than 1800
ft/min, which remains to be explained.

Some messages might be consistent with unreliable airspeed indication
but require further analysis. Other messages likely result from further
aircraft evolution and/or crew actions. Finally system status messages
have also been transmitted but are not relevant for the understanding
of the event.

The data available at this stage of the investigation:
- does not suggest any loss of electrical power supply,
- does not suggest a loss of instrument display,
- does not suggest an ADIRU misbehaviour as encountered in a recent
A330 event for 2 reasons: the ADIRU supplier and the signature of
failure related messages are not the same as on AF447,
- does not explain the complete sequence of events which led to
AF447 accident.

Airbus continues to provide the full technical support to the BEA in
the frame of the on-going ICAO Annex 13 investigation.

Airbus also provides support to EASA (European Aviation Safety Agency)
to assess if there will be the need or not for further precautionary
steps. Airbus will inform operators should either Airbus and/or
Investigation Board and/or Airworthiness Authorities determine the need
for further precautionary measures

Regarding the pitot tube, the fleet is currently fitted with 3
different standards: 2 from Thales supplier (std -AA and -BA, AF447
standard was -AA) and one standard from Goodrich. Concerning the Thales
standard, the latest -BA standard has been developed to enhance water
drainage encountered during heavy rain conditions on take-off or
landing phases.

Pending further investigation inputs, Airbus confirms at this stage
that the fleet in its various pitot tube standards can continue
operations and take the opportunity to recommend operators to remind
their pilots on the applicable and existing operational procedures as
recalled in the AIT n°2.

Airbus understands the need to share accident data with operators in a
prevention objective, while complying with communication requirements
set by the Official Investigation Board. This is why update on the
accident data will be provided as soon as further valuable information
is available and approved for release by the Investigation Board.
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Old 9th Jun 2009, 06:36
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Given that no-one has yet indicated where the VS was found, isn't it a bit early to be deciding whether it was cause or effect? If the VS came off at altitude and "floats like a leaf" through the air then it would in all likelihood have been some distance from the main debris field and the Brazillians (who appear to be doing an excellent job) would have had one heck of a job to find it. If (as seems likely) it WAS with the main field then it may have still been attached to the airframe even - depending on attitude - at beyond the point of impact.
It isn't possible to make an infinitely strong aircraft. If sufficient forces apply, something will break, but at this stage we really don't know whether the strong force was aerodynamic or hydrodynamic.
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Old 9th Jun 2009, 06:42
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This is naive. We have on the record another case of turbulent air leading to the pilot-induced loss of the vertical stabilizer and then the whole airplane, under perhaps more forgiving conditions. The problem was in the composites themselves. Before, I think it was always assumed that a pilot could not tear up his airplane just by trying to fly it.

-drl
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