AF 447 Search to resume

[llagonne66]

Promani

My reference to the QFA A380 engine near-accident was that, in a very tight situation (dealing with over 50 ECAM messages), they had the luxury to be (by pure chance !!) five in the cockpit.
And incidently, to fly in fair weather ...

The two poor souls in the cockpit of AF447 were all by themselves to deal with a huge workload ... in very severe weather conditions.

[Svarin]

Flight Controls

Lonewolf50 said :

[...] it appears that PRIM 2 had already failed before it was called upon to act as the back up [...]

Unfortunately, PRIM2 did not fail, else we would have a PRIM2 FAULT somewhere, which we don't. This is a silent "failure".

which perhaps provided the two gents on the flight deck the dubious honor of becoming test pilots ... without a test plan, with a load of pax, and with no briefing for the data points to be collected.

Thank you, Lonewolf...

[bearfoil]

The two pilots called up FPV because they wanted Pitch from the bug for Pitch and Power, No? This bus had no AHI?

Meaning they were conscious, and were handed what Will Fraser called a "wet Enchilada in the lap".

[Lonewolf_50]

Unfortunately, PRIM2 did not fail, else we would have a PRIM2 FAULT somewhere, which we don't. This is a silent "failure".

Svarin, as I am not smart at all on the maintenance and system fault system that uses ACARS reporting, what is the chance that this particular error message was erroneous? Does the system not get a false positive now and again?

If it does, then typically I'd expect that when the aircraft got to an operating base, the mechanics (you all call them engineers?) would run a diagnostic, find "no fault" and clear the fault or sign it off as "could not replicate via troubleshooting steps A through Zed" or something like that.

With that idea in mind, I will assume that maintenance records, and thus ACARS logs, from all previous flights ( or all previous flights after a given date and time) were available for the BEA to review? Or, did BEA get the filtered maintenance records that were a result of ACARS reporting and subsequent trouble shooting and fault remedy?

I ask this with an eye to anyone being able to reconstruct a trend analysis of various faults, or non faults, related to the systems in question. (When FDR and CVR are found, the importance of ACARS systems fault data may fall well into the background).

[Gringobr]

Change in dicussion??

Part of the plane where he was the black box flight 447 was located, say victims' families

The tail of the Airbus A-330, where the black boxes are located was flying from Paris to Rio de Janeiro and plunged into the Atlantic on the night of May 31, 2009, with 228 people aboard, has been found.

The information was confirmed by the president of the Association of Families of Victims of Air France Flight 447, Nelson Faria Marine. He said the information was given by the Office of Research and Analysis (BEA, the French acronym), a meeting yesterday (11) in Paris.

According to Marino, who had brought from Europe a report with data provided by unions, pilots and experts that would indicate failure of the aircraft manufacturer and maintenance issues with Air France, the finding reinforces the hopes of relatives of victims to know the causes of the accident . He said the expectation is that three weeks in an American company specializing in deep-water rescues start gathering the wreckage.

The representative of victims' families complained about the Brazilian ban by the French authorities, the presence of a diplomat appointed by the Brazilian government during the meeting that discussed the progress of the rescue operation. In addition, BEA, who wants secrecy and exclusivity in the searches, did not authorize the presence of a Brazilian observer - a request made by households and guaranteed by the Brazilian Defense Minister Nelson Jobim - to follow the step of removing the wreckage, bodies found just over a week to 3,900 meters deep.

Marino said the French authorities have not heeded any of the suggestions given by the Brazilian association of victims' families. He said the French say they only examine the claims if they come directly from the Brazilian government.

- The Presidency of the Republic and the Ministry of Defence are helping us and, just yesterday, I e-mail communicating the fact of [the French do not heeding the suggestions] to them - he said.

- I'll have audience with the president Dilma to address these issues. The families are in difficulties. While Air France has received four months in compensation for the loss of the airplane, the family until today [two years after the accident] did not receive a penny - told Marino.

Parte do avião onde estava a caixa-preta do voo 447 foi localizada, dizem famílias de vítimas | Mundo

[Khashoggi]

And what is the legitimate need of the BEA to have secrecy over the investigation?

[PJ2]

Svarin;

Originally Posted by #3383

This means both left and right pilots clicked their FPVs ON and found them failed.

To be precise, there is only one "FPV" pb on the FCU, in the center of the panel. This HDG-V/S:TRK/FPA pb toggles the FD presentation on the PFDs, and FCU mode selections, between "Heading, Vertical Speed", and "Track, Flight Path Angle".

Each pilot has an FD pushbutton which turns the respective FD on or off. FD1 and FD2 are driven by FMGEC1 and 2, respectively and the correct FMA annunciation when both FDs are on and driven by their onside FMGEC is "1FD2". If one FMGEC is offside (fault), say FMGEC2, the annunciation would be 1FD1 on both PFDs, meaning FMGEC1 is driving both FDs, etc.

For the FPV fault to occur, the Hdg-VS/Trk-FPA pb would have to be selected to FPV and one or both FDs selected ON. It would be at the point of selecting an FD ON that the message would be generated, (as it was requesting data that was unavailable).

We cannot know why, or if, the crew intentionally selected the FPV mode for guidance - you're right - it would not be useful guidance (unless one was very good at quickly interpreting and practised at using FPV information). One can toggle very quickly between the two as the button doesn't have much resistance. The selection could be by accident as one's hand was reaching for another control on the FCU or it could be intentional.

02:11:55 WRG:ADIRU1 BUS ADR1-2 TO FCPC2, HARD
(FCPC2 is PRIM2)
What the heck does this message mean?

Good catch on "WRG", Svarin.

I apologize in advance for what follows. I'm trying to convey the meaning of "WRG". From what I'm able to read and understand, this has to do with the verification of faults by the FWC [Flight Warning Computer].

As soon as an internal or external fault is isolated, it is considered as being at DETECTED status. The FWS computer which detected the fault has to confirm it. When confirmed, the fault is "declared". A declared fault is sent to the CMC, [Central Maintenance Computer].

Such a fault is then "consolidated". A consolidation is performed by the computer which declared the fault, which consists in checking the duration of the fault or its recurrence. As we know from past info, if the fault is still present after 10 seconds or if it occurs 3 or more times during the flight, it is "consolidated".

A fault which is declared not consolidated is transmitted to the CMC as being an "intermittent" fault. A fault which is declared consolidated is transmitted to the CMC as being a "hard" fault.

A declared fault, whether it is consolidated or not needs to be "correlated" to see more precisely where the fault is. Each FWC starts a correlation process. This correlation is performed on the ARINC buses and on the analog data.

So, here's an example of a message not correlated:
If a fault is detected only by one FWS computer, the associated message will be: FWCi(1WWi)/WRG:FMGECn BUS E GEN TO FWCi

- Example of a correlated message:
If the same fault is detected by two computers of the FWS, the associated message will be: FMGECn(1CAn) BUS E GEN

Consolidation must be done before correlation can be done by the FWCs and the correlation process is contingent on the type of architecture of the connections between the LRU [Line Removable Unit - the PFM boxes] checked, and the computers of the FWS.

I believe this means that the fault indicated cannot be pin-pointed with as much accuracy.

[infrequentflyer789]

Originally Posted by Khashoggi

And what is the legitimate need of the BEA to have secrecy over the investigation?

Probably none. In fact they've released an awful lot of info and several interim reports. More than we get in advance of final report (or even at final report) in most other investigations.

The refusal of a Brazilian observer is IMO most likely a bureaucratic / diplomatic tit-for-tat.

Remember that earlier in the investiagtion the Brazilians denied the BEA access to the autopsies and the results ? What was their legitimate need for secrecy from the investigation ? Something about the request not coming from the government at the right level if I remember correctly... and now we have the complaint of Brazilians being excluded and:

He said the French say they only examine the claims if they come directly from the Brazilian government.

Quelle surprise.

Moral: do not attempt to play the French at Bureaucracy, they have rather a lot of experience at it, and they will not forget a slight.

[mm43]

Originally posted by Svarin ...
One interpretation is PRIM2 loses connection with ADR1 (part of ADIRU1) through a failed bus. BEA explained it away with "PRIM2 rejects ADR1"... However, this particular failure does not seem to have anything to do with unreliable airspeed and ADR comparison, it is quite obviously an electronics connectivity issue : WRG means wiring, gentlemen. Airbusese for "warning" is WRN.

How strange is it that such an event, electr(on)ical in nature, would be simultaneous with the failed probes, which has external causes (icing) :

02:11:49 PROBE-PITOT 1X2 / 2X3 / 1X3 (9DA), HARD

Thanks for your the analysis of the ACARS messages, and I should point out to others that Svarin has posted other thoughtful insights into what may have happened, and they are spread throughout the AF447, Air France A330 accident, and AF447 Search to resume threads.

My initial comment is that the WRN messages took precedence and the F/CTL ones that were flagged took overall precedence - as one would expect. Something tells me that the 02:10 FCPC2 (2CE) WRG: ADIRU 1 BUS ADR1-2 TO FCPC2 may have been precipitous to the whole sequence, as a wiring fault manifest itself in turbulence. The unreliable airspeed data could be put down to an unplanned nose-up command to the THS, resulting in the rapid bleed off of airspeed as the A/P and A/THR found themselves in new territory (and beyond their limits) - not to forget the "test" pilots.

What does ADR1-2 mean, i.e. the "-" part?

Why should the BEA dismiss it as PRIM1 rejects ADR1? Possibly because there were other known events that could be linked to the Pitot Probes, and it gave a means of addressing that issue while reserving the right to determine otherwise when the recorders were found and analyzed.

PJ2 has explained that a fault which is declared consolidated is transmitted to the CMC as being a "hard" fault, but in this case it has not been correlated. Perhaps the CMC saw fit to declare this fault once as a Maintenance issue, knowing that on the ground any correlation would be followed up, and the initial ACARS message is all that is required. The most noticeable point, is the 0210 time-stamp, and why would a wiring/connectivity fault suddenly show up in the course of other mayhem. More likely the wiring fault came first and caused the mayhem.

A lightning issue? No, as has been explained previously, none was detected in the area during the course of this event.

[auv-ee]

New AP article has BEA statement about the tail and black boxes

This article from AP quotes BEA confirming that the tail has been found but emphasising that the black boxes have not been seen.

News Headlines

[techgeek]

On G limits vs CFIT

Gotta love this quote from an ALPA report on system limitations on pilot authority:

"Although aircraft structural integrity may be compromised by a g load in excess of 3.8 gs,
aircraft structural integrity is more severely compromised by terrain impact."

(The 3.8gs is in regard to a design load limit of the A-320)

[broadreach]

With regard to BEA's deciding not to have a Brazilian family group representative on board Ile de Sein during the recovery process, probably a good idea. One assumes there will be no rep for French or any other nationality family groups either; none would contribute to the job in hand and they could easily complicate things unnecessarily.

One also has to doubt Brazilian participation from here on in. The ports of Suape and Recife have been used as bases for the first stages of the search because they're the closest but, given the emotional content, the "Ile de Sein" continuing to use one of them while carrying wreckage and body evidence would be tempting all sorts of legal interference.

Better to base in Cape Verde if, in fact, more than one wreckage recovery sortie by the "Ile de Sein" proves necessary.

"Alucia", btw, appeared on AIS off Suape this morning but has since disappeared; she may have switched off. "Ile de Sein" continues to show fleetingly in the Canaries.

[promani]

Quote from AP "Nelson Marinho, who heads the Brazilian victims' family association, said that if the black boxes are recovered, he and other victims family members want the data analyzed in a "neutral" country, preferably the United States."
Well as the Ile de Sein is a French ship, owned by a French company, and had been dispatched by the French, he has more chance of winning a lottery than succeeding in his desires.
If they have found the tail, and in good condition, then why is there no news on the recorders?

[Bobman84]

Originally Posted by promani

If they have found the tail, and in good condition, then why is there no news on the recorders?

Let's find out.

Enough of 100s of pages of speculation on the cause of the crash when the thread is for the actual search and recovery which is currently ongoing.

[auv-ee]

Originally Posted by promani

If they have found the tail, and in good condition, then why is there no news on the recorders?

Because the AUV cameras look straight down from the altitude of the AUV, probably 10m (+/-5m). Hopefully, the recorders are still in the tail, and simply can't be seen when viewed directly from above. Less likely (due to the required coincidence) one or both recorders are elsewhere and covered by another piece of debris. I expect the tail will be the first stop for the ROV, which will have the ability to look inside and under things.

[CONF iture]

Originally Posted by Svarin

there is one possibility for a very fast deceleration from cruising speed to stall speed (low speed, high AOA stall), and that possibility was only brushed by a few people here : pulling back hard on the elevator controls.

I believe such scenario would have triggered some kind of load report for G exceedance somewhere in the ACARS messages.

Originally Posted by PJ2

For the FPV fault to occur, the Hdg-VS/Trk-FPA pb would have to be selected to FPV and one or both FDs selected ON. It would be at the point of selecting an FD ON that the message would be generated, (as it was requesting data that was unavailable).

I don't think it was necessary to select one or both Flight Path Directors ON to get the FPV red flags. An issue with one FPD would trigger a separate FD red flag and probably a different fault msg.

[JD-EE]

Graybeard, the signal path is not quite that simple. There is a gadget called a circulator in there which protects the receiver front end from the transmitted signal and routes the majority of the received signal from the antenna to the receiver front end. The circulator is not perfect. 40 dB is good. 50 dB is darned good. But it plus an electronically switched attenuator can protect even fragile 1N34 diode front ends let alone the nice schotkey diode front ends we used in the 70s. That leakage signal is a VERY nice BIT feature. It's strength is "more or less" constant. You can certainly tell if the transmitter failed or if the front end packed it in. Both cases mean too little signal received. If the antenna has a physical fault to it that disconnects the waveguide that results in WAY too much signal leaking around the circulator. (It bips out of the transmitter through the TX path on the circulator to the open ended waveguide. Most of the signal is reflected back and takes the RX path to the radar set's front end.) So you have a tremendous amount of nearly free BIT. Similar BIT features on the antenna mount can handle aiming issues neatly. It's a feedback positioner and it is pretty obvious to the pointing software that it's not getting position feedback when it commands motion.

That handles a large range of the possible errors. If the temperature of the circulator is monitored and a calibration for it exists you should be able to detect even modest transmitter or receiver degradations, say half power or so.

I remember in the era that would have been designed that at least the Navy was frantic about having good BIT features on things like the S3A sonobuoy receiver. I'd expect the FAA to be at least as diligent. But, then, maybe not.

[JD-EE]

Lonewolf_50, sorry I phrased it badly. I was suggesting you might have been derelict not to mention that point to support your argument. It's a very telling point, at least to me.

[JD-EE]

Chris: "Yes, but gentle descent seems unlikely in this case."

It's past unlikely given it was over the ocean and GPS and IMU were working. So they'd have had VERY good information about their altitude. With a digital control system there'd not even be slow analog drift.

[JD-EE]

BOAC, discussions here led me to believe it was standard practice for one of the cockpit crew to have his mask on so that if something went wrong with the air supply he'd still be alert enough to fix it.