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AF447

Old 10th Jun 2009, 04:44
  #1001 (permalink)  
 
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Excellent Points by captainflame

Captain Flame posted:

Let's put this one to rest once and for all !

The message F/CTL RUD TRV LIM Fault is justified by the loss of the ADR data.

As said previously in this thread, the rudder travel is then limited to 10 degrees and full deflection is only recovered at slats extension.

An Air Caraibe A330 incident report is circulating (in french) which describes a (survived) event sounding very similar to the AF447 event.

In the air Caraibe event (which I will try to find in english)....icing over of the Ptot probes and TAT probe at FL 350, in transoceanic equatorial WX, with severe turbulence, occured.
The following ECAM messages, flags and system reversions are consistent with the ones reported ont the AF447 ACARS report.

As decribed earlier in this thread, the TAT increase from -14 to -5 degrees typical of an iced up probe measuring the ice temperature instead of the Ram Air.
At some point in this event the CAS, MACH and ALT go respectively from 274Kts, M0.80 and FL350 to 85kts , M0.26 and FL347.

At the same time the cascade of ECAM warnings and cautions include NAV ADR Disagree, F/CTL ALT LAW, F/CTL RUD TRV LIM, ENG EPR mode faults (different engines there), Speed Flags on PFDs, loss of FDs, A/THR, etc....Including at some point STALL STALL audio warning (no protection in ALT LAW)

Summarily, the PF flew "pitch and power" with PNF on QRH unreliable speed indication, disregarding the STALL warning and using backup info of GPS Ground speed and Altitude (ND and FMGC).

Air Caraibe has modified all the 330 probes earlier this year.

Again, the Air caraibe report is VERY similar to what is now known of the AF447 troubles. (Weather, turbulence, airspeed data problems)


Guys I'm on the other side of the world, so while most of you are posting and moving on to other subjects, I'm counting sheep and then still responding to the "resolved" posts the day before! Forgive me if I'm five pages behind.

I hadn't read this A330 report earlier even though I downloaded it. Even though it is in French, It's clear most of the "events" logged about the accident/incident are almost identical. As the good "Captain Flame" stresses the engine EPR differences are moot, they are just airline customer engine selection options: For example on the previous gen aircraft the A310, you could order with Pratts w/EPR or GE's w/out EPR. In the latter case, since all you have is N1 for thrust settings you wouldn't get EPR (engine pressure ratio) errors logged (since you don't have those gages), you wouldn't see those EPR faults or warnings into the mtc computers. The aircraft system then reports these conditions to ACARs, and ACARs would then bundle this information into a data packets and beam it to the satellite or HF if, that service was paid for.

To oversimplify for non aviation types: ACARS is a telephone. If the Cable Guy (Installer) has problems with your TV/black box, he's going to ask you to use your telephone (ACARS) to report the faults to somebody back at his company (AOC/Maintenance Control) who is smarter than he is. Previous posters asked where the location coordinates for the last 0214z acars report came from since it didn't show up in the acars report. This is a good question. It appears the images on the first few pages of this thread from Channel2 France, are of a finished "environmental" report constructed for AF maintenance. We are not seeing the actual data packets (which would have sat broadcast coordinates,) which are broadcast line-of-sight to the satellite in a different computer language.

Here are excerpts from Wiki on ACARS:

SATCOM and HF subnetworks
SATCOM provides worldwide coverage, with the exception of operation at the high latitudes (such as needed for flights over the poles). HF datalink is a relatively new network whose installation began in 1995 and was completed in 2001. HF datalink is responsible for new polar routes. Aircraft with HF datalink can fly polar routes and maintain communication with ground based systems (ATC centers and airline operation centers). ARINC is the only service provider for HF datalink.
[edit]Datalink message types
ACARS messages may be of three types:

Air Traffic Control (ATC)
Aeronautical Operational Control (AOC)
Airline Administrative Control (AAC)

ATC messages are used to communicate between the aircraft and Air traffic control. These messages are defined in ARINC Standard 623. ATC messages are used by aircraft crew to request clearances, and by ground controllers to provide those clearances.
AOC and AAC messages are used to communicate between the aircraft and its base. These messages are either standardized according ARINC Standard 633 or defined by the users, but must then meet at least the guidelines of ARINC Standard 618. Various types of messages are possible, and these include fuel consumption, engine performance data, aircraft position, as well as free text data.....

(Each airline must tell its service provider(s) what messages and message labels their ACARS systems will send, and for each message, where they want the service provider to route the message. The service provider then updates their routing tables from this information.) Each type of message sent by the CMU [Communications Management Unit - CC] has a specific message label, which is contained in the header information of the message. Using the label contained in the message, the DSP looks up the message and forwards to the airline’s computer system. The message is then processed by the airline’s computer system.
This processing performed by an airline may include reformatting the message, populating databases for later analysis, as well as forwarding the message to other departments, such as flight operations, maintenance, engineering, finance or other organizations within an airline. In the example of a delay message, the message may be routed via the airline’s network to both their operations department as well as to a facility at the aircraft’s destination notifying them of a potential late arrival.
Those who claim that the ACARs data doesn't mean anything, are incorrect.
These messages are the best information we have thus far and they appear nearly identical to other A330 known mishaps. If history is any guide, since billions are on the line in Aircraft Ops and Sales, it may be years before the findings of this investigation are made public.

All my posts are just my opinion only.


CC
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Old 10th Jun 2009, 04:52
  #1002 (permalink)  
 
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Originally Posted by 727gm View Post
Not saying ACARS messages are related to loss of VS.
............................................Doesn't help thread to try to put words in other poster's mouths.
Actually your post appeared to have alluded to this indirectly. I responded, but relented and was deleted.

No harm done I hope. It was getting tiring hearing about vertical stabilizers and the loss of AF447. The two are unrelated at this point as a causal factor according to the information, scant as it is, provided so far.

Even the Seattle Post had an 'engineer' claim the Rudder TRVL Limit message was not a reported fault of the limiter, most likely due to the loss of ADIRU data, but an actual rudder over-excursion.

I had previously posted a correct interpretation by a retired but qualified A330 engineer to the contrary and explained it in this post of mine earlier.

Sorry if I was a bit too harsh 727gm.
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Old 10th Jun 2009, 05:30
  #1003 (permalink)  
 
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limits and the forum

As a non-pilot, but a denizen of the web since '89 I would argue that though discussion of posting rights, or posting rankings *may* have merit. Locking the forum to pilots only is not in the best interests of anyone. The purpose of the http protocol was and is the providing of information to all without qualification of their *right* to access it. I still long for the day long past when I could "talk". (Old unix cvommand) to anyone with a email address and logge on and receive an expert opinion. Yes the uneducated tend to offer bad info, but good info comes with sources and supporting arguments. Allow me a source of knowledge, my government and my media do enough to protect my fragile mind already .
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Old 10th Jun 2009, 05:42
  #1004 (permalink)  
 
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About crew rest

The first Airbus cockpit crew rest (A340-300) was two bunks accessed directly from the flight deck. It wasn't popular because there was no sitting area and it tended to be noisy.

On current A340s it normally occupies part of the bulk hold space, so a long way from the flight deck, but equipped with proper seats. I'm not sure if this is available on the A330-200. Maybe an AFR person can tell us.

The debris from AF447 with "crew rest" on it almost certainly indicates it's an LDMCR - lower deck mobile crew rest. This container-like module, primarily intended by Airbus to be for cabin crew rest, occupies the forwardmost position in the rear hold. Again, maybe someone from AFR can tell us whether this was being used as cockpit crew rest.
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Old 10th Jun 2009, 05:43
  #1005 (permalink)  
 
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Agreed on the inputs to TCAS, Plastic Bug. I believe the TCAS Fail came before the IR Fail, though. Not so?

I'm from the planes of separate DADC and IRU, where the failure of one, or a component of one would not condemn the output of the remainder. Is that still not true? Can you not get Airspeed Fail out of the ADIRU without Altitude Fail? If not, it's a giant step backward.

I suppose it's possible for the airspeed word to go Fail Warn, with Altitude reporting Normal (condition), and getting lumped together in the ACARS message as ADR Fail. After all, MTC just needs to know which box to change..

GB
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Old 10th Jun 2009, 05:56
  #1006 (permalink)  
 
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TCAS is just a visualization and warning processor based system to the pilots. If you loose it, you will still have Mode S ATC XPDRs, but the opposite is not true, if you loose ATCs, you won't have TCAS.
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Old 10th Jun 2009, 05:56
  #1007 (permalink)  
 
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What looks like 85km apart could easily be 100 metres even without divergent currents

Unless I missed the times at which these two bodies were found then we can conclude nothing. If one was found at A and the other days later at B then all we need is that they were far enough apart for the second one not to be seen when the first was recovered and normal currents would then move it somewhere else in the intervening period. We do not need diverging currents at all.

Of course, the Brazilian Navy have the data, they can superimpose the drift and decide if the data is inconsistent with intact entry to the sea. We can make no such inferences at present.
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Old 10th Jun 2009, 06:06
  #1008 (permalink)  
 
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Great Work Greybeard

Greybeard said:
Thanks for the diagram of antenna locations, Saigon Lost. It gives evidence that the vertical fin was intact throughout the period of the ACARS reports, else there would have been HF Fail reports, too. The VOR antennas are not monitored, but the HF antenna couplers, in the leading edge of the vertical fin, are active LRU, Line Replaceable Units, that are powered, and provide fault reporting to the transceivers, which would, in turn, report to the ACMS, and from there to ACARS.

GB


Great Work Greybeard! The HF was most likely operational until 0214z (we say this, because of the absence of a LRU ACARS message of it being faulted). Therefore, the vertical stablizer was intact and had not left the airplane before 0214z.

This Means that the ACARS messages probably preceded the fatal loss of control event.

(recall, that my high dive estimate is 60 seconds from jet upset FL350 to 10-14K recoverable air. Please challenge this if you can prove a different elapsed time from FL350.)

Again, outstanding work guys.

This board is way more than speculation with guys like Greybeard posting.

CC

Last edited by Captain-Crunch; 10th Jun 2009 at 06:31. Reason: made it more pretty, added GB quote
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Old 10th Jun 2009, 06:25
  #1009 (permalink)  
 
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Thanks for the diagram of antenna locations, Saigon Lost. It gives evidence that the vertical fin was intact throughout the period of the ACARS reports, else there would have been HF Fail reports, too. The VOR antennas are not monitored, but the HF antenna couplers, in the leading edge of the vertical fin, are active LRU, Line Replaceable Units, that are powered, and provide fault reporting to the transceivers, which would, in turn, report to the ACMS, and from there to ACARS.
we say this, because of the absence of a LRU ACARS message of it being faulted
I just wish we knew:

-the complete unfiltered information as transmitted by AF447 (what was transmitted)
-a list of all possible failure and warning items specified by AF for immediate transmission. (what qualifies for transmission)

Last edited by Interflug; 10th Jun 2009 at 11:04.
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Old 10th Jun 2009, 06:30
  #1010 (permalink)  
 
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Originally Posted by Captain_Crunch
.... This Means that the ACARS messages probably preceded the fatal loss of control event. Again, outstanding work guys. This board is way more than speculation with guys like Greybeard posting. CC
So you\'re saying the plane encountered trouble before it went out of control? And VS detach wasn\'t the cause?
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Old 10th Jun 2009, 06:37
  #1011 (permalink)  
 
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The A330 AMM looks very similar to the A320’s.

So, for all experts here goes the “chapter decoding” of the ACARS messaging.

Please note that all lines stating “maintenance status” at the end of the line are Class II faults, therefore not critical.

And yes, the Aupilot will disengage if it feels it’s not able to control the A/C in severe weather.

2723………. Rudder travel limiting
2283………. FMGEC
2283………. FMGEC
3443………. TCAS
2230………. A/THR
2283………. FMGEC
2283………. FMGEC
2791………. EFCS
2262………. FMGEC – FLIGHT ENVELOP
2210………. AP/FD
3831………. (WASTE) LAVATORY CONFIG
3831………. WASTE VACUUM SYSTEM GENERATOR

2131………. CPC (CABIN PRESSURE)
2283………. FMGEC
3410………. ADIRS MAINT STATUS
2790………. FCSC 1 FAULT
2790………. FCPC 1 FAULT
3412………. ADIRU 2 INOP
3412………. ISIS (ELECTRONIC STBY HORIZON)
3410………. AIR DATA DYSAGREE
3412………. ADIRS
3412………. ADIRS
2793………. FCPC 1 FAULT
3411………. PITOT 9Dax PROBE INOP
2790………. EFCS MAINT STATUS
2790………. EFCS MAINT STATUS
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Old 10th Jun 2009, 06:48
  #1012 (permalink)  
 
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Thanks JMIG29 But is it staggered or is it a complete disengage, and what are the parameter for partial? I ask because maybe the pilots found themselves with incomplete control after a partial AP disengage. [brk] And maybe they weren\'t aware of it- wouldn\'t be the first time.
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Old 10th Jun 2009, 06:57
  #1013 (permalink)  
 
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Complete pitch and roll auto comand is lost. Rudder comand is always present from FCPC's (I think, remember I'm not familiar with this A/C) which acts pretty much the same way of FAC's and ELAC's, on A320.

Unless it moves out of normal law, down to direct law.
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Old 10th Jun 2009, 07:10
  #1014 (permalink)  
PJ2
 
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The information provided on Alternate Laws 1 & 2 from an A330 AOM ATA Chapter 27. While the ACARS message 2791 indicates "F/CTL ALTERNATE LAW, we do not know what caused the flight control reversion The potential causes are listed in the previous post:

ALTERNATE LAW 1

PITCH CONTROL

Ground mode
Identical to normal law ground mode.

Flight mode
Flight law is a load factor demand law, similar to normal law, with limited pitch rate feedback and gains, depending on speed and configuration.

Note : When the yaw dampers actuators are not available (hydraulic G + Y failure for example), the yaw damping function is made through the ailerons and the BYDU.

Flare mode
Flare law is identical to normal flare law.

LATERAL CONTROL
Lateral control is similar to normal law, except that alterations of positive spiral static stability will not occur due to the loss of high AOA and high speed protection.

PROTECTIONS
Low speed stability
At low speed, a nose down demand is introduced in reference to IAS, instead of angle of attack, and alternate law changes to direct law.
It is available, whatever the slats/flaps configuration, and it is active from about 5 knots up to about 10 knots above the stall warning speed, depending on the aircraft's weight and slats/flaps configuration.

A gentle progressive nose down signal is introduced, which tends to keep the speed from falling below these values. The pilot can override this demand.
Bank angle compensation is provided.

In addition, audio stall warning (crickets + “STALL” synthetic voice message) is activated at an appropriate margin from the stall condition.
The PFD speed scale is modified to show a black/red barber pole below the stall warning.

Vα prot and Vα max are replaced by Vsw (stall warning speed).
The α floor protection is inoperative.

ALTERNATE LAW 2

PITCH CONTROL
Identical to ALT 1 law.

LATERAL CONTROL
Roll direct law
Provides a direct stick-to-surface position relationship. The gains are automatically set according to the slats/flaps configuration.

The maximum roll rate is approximately 20 to 25° / second, depending on the speed and
configuration.
Spoilers 2, 3 and 6 are inhibited, except in case of some additional failures affecting the lateral control.

Yaw alternate law
The dutch roll damping function is available, and damper authority is limited to ± 4° rudder (CONF 0) and ± 15° (other configuration).
Turn coordination is also provided, except in CONF 0.

PROTECTIONS
Identical to protections in ALT 1, except that :
1. There is no bank angle protection in ALT 2 law.
2. In case of failure of 2 ADRs, there is no low speed stability.
3. In case of failure of 3 ADRs, there is no high speed stability.

Last edited by PJ2; 10th Jun 2009 at 07:51.
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Old 10th Jun 2009, 07:44
  #1015 (permalink)  
 
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Just a couple of questions (no expertise aside from being CC flying on the Airbus family)

I've tried reading through but this thread has gone from page 33 to 43 in the time I've been reading.... so, apologies if this has already been answered.

I know there are a couple of posters here involved in SAR operations... would use of satellite imaging be at all useful in helping to locate debris/people and so on... I mean some posters are saying there is a lack of a 'dense debris field'.. but how can we really know that in such a large area? (currents/winds prediction aside) Could there be other areas of debris/people which will not be found for days/weeks/months/ever? So would there be any coverage to a degree which would give any help in finding (large) areas of debris, or is it kept to the old grid/search pattern method by air/sea vessels? Would anyone in possession of such pictures likely not be willing to admit it (for political reasons)?

and 2.

Why is everyone getting so hung up on radios/comms/maydays etc, when we may not ever know if the crew did, or did not, communicate... simply put, (and I'll ask as a question to refrain from 'speculating') could they have been trying multiple times to have contact and it was never heard? I gathered from earlier postings this could be the case given the remote area & being out of the radar coverage/difficulties with HF etc in weather... not to mention having their hands full.

Again, I leave it to those with more experience than I, was just wondering about the satellilite thing today while looking out the window thinking what a wide area the ocean is from that high...
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Old 10th Jun 2009, 08:00
  #1016 (permalink)  
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May I just interject to let you know that the JB thread (as ever, well-moderatedin a JB sort of way) has a lot of good stuff on it and may be worth keeping an eye on. You'll have to ignore the usual JB crap, the Comet crash stuff and the immoderate rantings of Captain Stable against Arcniz, but a few reasoned posters appear to have sought refuge there from this jungle. A couple of unseen pics there too.
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Old 10th Jun 2009, 08:11
  #1017 (permalink)  
 
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Red face French Airforce

Interesting, where did you find that info, I was looking at the site but found nothing?
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Old 10th Jun 2009, 08:50
  #1018 (permalink)  
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My apologies to the 'newbies'. Here is the link

2 more:

Can we stop asking about whether the Captain was in bed at the time/issues of crew rest etc? I cannot envisage ANY captain faced with crossing the active ITCZ and with 6-7 hours of 'peaceful' cruise thereafter, retiring to bed and leaving the rest of the pilots to 'get on with it'.

Are there any AF pilots here who can elaborate on the (supposed) crew report of 'turbulence fortes'? Is that an established AF description?

Last edited by BOAC; 10th Jun 2009 at 09:04.
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Old 10th Jun 2009, 08:58
  #1019 (permalink)  
 
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Post

Apologizing if I missed it up here -
There seems to be a new EASA recommendation concerning unreliable airspeed indications. Airlines are requested to keep crews current and checked on the procedures.

Source (german)
EASA gibt nach Absturz im Atlantik Sicherheitsempfehlung an Airlines heraus - FLUG REVUE
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Old 10th Jun 2009, 09:10
  #1020 (permalink)  
 
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I don't buy into the; "They lost the VS and crashed" theory, but would a missing HF antenna coupler/LRU trigger a HF fail message? Is this a monitored device, or does it transmit an error message itself?
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