AF 447 Search to resume (part2)

[gums]

Part 1 of this thread can be found Here (http://www.pprune.org/tech-log/395105-af-447-search-resume.html)


Need some of you "bus" drivers to clue me in re: autopilot authority and inputs.

If the pitot-static inputs go tits up, what happens? The B-2 crash was a result of several sensors being filled with water and the jet tried to climb like hell just after WOW. Seems like an "attitude" control law would have helped those two guys.

So my theory all along is the pitot-static system went south and the crew didn't react properly and/or the autopilot didn't revert to an "attitude" mode. Sheesh. All of us that have flown into CB's or had a pitot-static ice problem and simply held attitude and didn't chase speed or altitude until we figured out our problem. Keep wings level and a semblance of level attitude.

In several instances I was glad that the Viper control laws were gee- command and roll rate. Let go of the stick and the jet would try to keep trim gee and zero roll rate. I have a hard time with all the "control laws" for the "bus". Glad I am not/ was not a pilot of the beast.

[HazelNuts39]

Did all Tx (ACARS) arrivee via FIN??The BEA report #1, 1.16.2.4 states that after 2:10 all ACARS messages passed through the same satellite:The messages received on 1st June after 2 h 10 all transited via the same satellite (Atlantic Ocean West, operated by the Inmarsat Company) and SITA’s ACARS network.

[bearfoil]

Hazelnuts39

Yes, of course, the ACARS that were released to the public. That is not demonstrably untrue, it merely would mean that the repeated ACARS stream broadcast after the antenna interruption by the SATCOM antenna/System had restarted with the first of the ACARS stream we have. (The "Overlap").

I have wondered why we see no activity of ACARS prior to those we have in the public domain. Weren't these released by a whistleblower, and if AF had those streamed by the Fin (VHF) that weren't released, why would they release those? I was given to undertsand that ACARs tx of preference is VHF (cost??). Golly, that is complicated, though, surely if they existed, BEA would release all the ACARS from this flight?

This of course means that 447 was airborne and Txable SATCOM if there was a repeat Tx by the flight. It would certainly allow that the pilots may have taken a breath prior to re-engaging the A/P?? Well, I am certainly beyond my expertise here.

[JD-EE]

HN39, just a short note, when I was developing some software for Inmarsat-M SatCom terminals I communicated regularly with AOW from Torrance through the ground station in Goonhilly. That gives you some notion of the theoretical coverage range. (My antenna was aimed below the horizon for the typical ACARS antenna though.)

[bearfoil]

I have wondered since the outset why there are no ACARS alerts via Satellite between the last two on the ramp at RIO, and the ones beginning at 0210.

Wouldn't there be at least a few? 447 was no virgin, and she must have had reportable defects prior to "The Sky is falling" at 0210. Or is radio abandoned at the intervals I would question?? Irrespective of antenna issues, what explains the dearth of ACARS coms??

[JD-EE]

Bearfoil, you are reaching way too far. You are presuming the airline is so cheap they'd send messages via HF rather than SatCom when the plane is SatCom equipped. And I am not at all sure HF would be even pennies a message cheaper. It would certainly be less reliable without some serious Automatic Link Establishment sort of technology. HF propagation is not necessarily a hands off operation without such technology.

You have a habit if making unsupported and too often unsupportable assertions. And you are back to your mantra that you said you never discuss, "the VS er Fin came off the plane and caused the accident." This gets REALLY tiresome, sir.

I'd also like to note that there was a previous trouble message included in the logs - one of the potties had a problem.

[HazelNuts39]

if AF had those streamed by the Fin (VHF)The fin has HF1/2, whereas VHF1/2/3 are on the fuselage.

[mm43]

Originally posted by bearfoil ..

I have wondered since the outset why there are no ACARS alerts via Satellite between the last two on the ramp at RIO, and the ones beginning at 0210.There was a LAV fault reported, and don't forget the AOC position reports were every 10 minutes via ACARS.

[JD-EE]

HN39, I'd also note that you ain't gonna stream via VHF out where the plane was no matter WHERE its antenna is. 100nm is about it for VHF give or take a factor of two. (I'm not going to bother to go look it up on the nomographs I have.)

[bearfoil]

For goodness sake. This thread is 100 percent conjecture and partial repetition of BEA regurgitatae...... The Potty pressure valve bollux and the Audio panel glitch were rampside, if I'm not mistaken, and frankly what is tiresome are people who eat mush blindfolded, without palpating it at least.

The audio panel was mel, I don't think the lav was important enough to make the list. The radio selects were of no small concern.

This entire exercise is nothing more than an intriguing diversion. To think any real results are to be found here is absurd. The reality of the exercise is what is elusive. The pilots knew. They knew. The a/c and ground support failed them, and by extension, all those in their loving and skilled care.

What is beyond tiresome is most here taking themselves far too seriously.

There are a few here for whom I have utmost respect, and frankly more for their grace than their respective expertise, inspiring though that be.

If anyone here thinks I am serious beyond an informed speculation and earnest question or two, please read me with tongue in cheek, as intended.

Christ on a freaking crutch.

[ACLS65]

JD-EE

"HN39, I'd also note that you ain't gonna stream via VHF out where the plane was no matter WHERE its antenna is. 100nm is about it for VHF give or take a factor of two. (I'm not going to bother to go look it up on the nomographs I have.)"

Where AF447 was it was out of range of VHF and ADS-B, and didn't have HF ACARS. It doesn't look like their is much amateur monitoring of ADS-B in that area.

In terms of previous ACARS messages I suspect there would have been VACARS transmitted via VHF3 prior to SATCOM.

The A330 Comm manual says that "ACARS normally transmits via VHF3. It automatically switches to SATCOM when VHF3 is not available."

Not quite sure if that means ACARS switches automatically when it is no longer receiving ACARS msgs via VHF3, or if by unavailable they mean something else.

[mm43]

Mr Optimistic posted a message at #9 in this thread, but has subsequently withdrawn it. The question posed was, "Is Svarin's analysis of the ACARS messages accepted?"

With the thread otherwise engaged, potty/lav included, I think the substance of what Svarin had to say in post #3858 (http://www.pprune.org/tech-log/395105-af-447-search-resume-193.html#post6408082) and post #3863 (http://www.pprune.org/tech-log/395105-af-447-search-resume-194.html#post6408147) in Part 1 of this thread has been overlooked.

In essence, the A/P and A/THR disconnected due to UAS. Cockpit activity is evidenced by -

2:12:10 WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV
2:12:16 WRN/WN0906010211 341201106FLAG ON F/O PFD FPV

Two pages not normally selected in the cruise.

Secondly, the A/P was reconnected 3 minutes after the UAS in what was apparently an unstable situation -

2:14:20 FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

possibly causing a pitch up command, a situation around which an Airworthiness Directive was issued this (northern) winter regarding A/P reengagement after an UAS condition.

I think that Svarin is probably correct, and I know that he has meticulously examined each of the ACARS messages and sought rational explanations for all. The answer was found in the "detail".

The CVR will be necessary to confirm what was going on prior to 0210.

[Machaca]

From EASA AD No.: 2010-0271 (22 December 2010):

REASON
http://i337.photobucket.com/albums/n385/motidog/EASA_AD_2010-0271_Reason.jpg

http://i337.photobucket.com/albums/n385/motidog/EASA_AD_2010-0271_Prodedure.jpg

[Khashoggi]

Assuming AF447 was intact on hitting the Ocean surface, could you explain the disparate condition of the floating wreckage by considering that the Ocean surface was not flat but instead had large wave action?

The BEA thinks there was low forward velocity, but a fuselage hitting a line of waves could cause multiple impacts, and various breaks and ejection of components under varying impact loads.

There was wx in the area, so presumably the Ocean wasn't smooth as silk that night??

[Mr Optimistic]

Sorry, thought my post was contentious (not a pilot so cautious). Svarin's post seemed informative but don't understand why after nearly 2 years anything new is coming from the ACRAS messages and if it is new why so little attention is given to it.

[HazelNuts39]

Maybe there is a difference between AP disengaged, AP lost, and AP off?

[broadreach]

Machaca,

Note the date of that!

EASA AD No.: 2010-0271 (22 December 2010)

Would there have been an AD along similar lines available prior to the accident?

[Machaca]

khashoggi - A very good point and quite correct. Yes, the irregular surface of the ocean did indeed play a large part in how the airframe and its contents were damaged and to what level.

It was discussed many moons ago in an earlier thread. Sadly, many have forgotten or disregarded much of the valuable and substantiated input that has been provided over the last 22+ months. Yet some proffer curious scenarios as if they were never contemplated beforehand. :ugh:

I don't know why it is so difficult for some to envision how a galley can be ejected relatively undamaged in such an impact with the sea.

[Machaca]

broadreach - AD 2010-0271 does not supersede any previous AD's.

[jcjeant]

Hi,

It has been identified that after such an event,if two airspeed sourcesbecome similar while still erroneous,the flight guidance computer will:

Do any one know the date and what event ... when this was identified ?

[Turbine D]

Bear

Contained within the OnPoint Program is the real time diagnostic program. There are two levels, Standard or Comprehensive, the Comprehensive can be custom designed to whatever the aircarrier would like. For what we would be interested in, the Standard program will show fault alerts, exceedance alerts and would notify the aircarrier of "critical" detected anomalies. The Comprehensive program would do the same as the Standard program but also would diagnose (diagnosis done by GE) the fault alerts and would detect all anomalies. So the data transmitted by each engine to GE & AF would depend on which program AF selected.

The data sent in either case would show all the key engine operating data, N1 and N2 speeds, oil quantity & temperatures, EGT readings, fuel consumption, air pressure entering the combustor, high vibrations, etc. The detected critical anomalies would include high EGT, flame out/compressor stall conditions, fire, commanded engine thrust levels outside normal operational conditions, etc.

I don't know what AF signed up for, but the data is very comprehensive and dates to the very first flight of the engine sending the data.

Sorry for the delay, but we have had bad weather here today...

[jcjeant]

Hi,

Assuming AF447 was intact on hitting the Ocean surface, could you explain the disparate condition of the floating wreckage by considering that the Ocean surface was not flat but instead had large wave action?

The BEA thinks there was low forward velocity, but a fuselage hitting a line of waves could cause multiple impacts, and various breaks and ejection of components under varying impact loads.

There was wx in the area, so presumably the Ocean wasn't smooth as silk that night?? I think it was already posted :)

3.32

http://www.youtube.com/watch?v=Ob8nE4f2ZWc

[Smilin_Ed]

Do any one know the date and what event ... when this was identified ?

Wasn't that after the Qantas upset?

[mm43]

HN39;
Maybe there is a difference between AP disengaged, AP lost, and AP off? What point are you trying to make? I assume it is in relation to the AFS part of the message.

In the ACARS list (http://countjustonce.com/a330/acars.html) there is mention of a "possible loss of signal" with the satellite. The actual fault received at 2:14:20 was probably initiated in that 2:13:16 ~ 2:13:41 time slot.

[Turbine D]

gums

Here is what can happen when the pitot tubes start to ice over and the pilots respond to the false (higher) speed/climb rate readings by throttling back. In this case it is pre-computer age.

http://www.airdisaster.com/reports/ntsb/AAR75-13.pdf

However,

All of us that have flown into CB's or had a pitot-static ice problem and simply held attitude and didn't chase speed or altitude until we figured out our problem. Keep wings level and a semblance of level attitude.

seems so right, if one recognizes the situation.

[CONF iture]

Wasn't that after the Qantas upset?
No, QF72 upset was not related to Unreliable Airspeed Indication.

jcjeant has a very valid question :
Which event was identified to justify the publication of the AD 2010-0271 and the related red OEB called Loss of AP and A/THR associated with alternate law reversion ... ?

[HazelNuts39]

mm43;

I was wondering whether an AP that had disengaged automatically, but had not been selected OFF, could still be the identifier in the FLR message (without having been re-engaged).

[gums]

Salute!

Thanks, Turbine.

The procedure outlined in machaca's post seems very reasonable. And I doubt that the AF crew re-engaged the autopilot if it had kicked off for whatever reason, especially in turbulence.

Many of us on this forum have experienced turbulence beyond the definition "moderate", heh heh. Last thing we did was have "otto" try to "help". I tend to go with the FBW systems, as they seem to avoid huge control surface movements, but apply the commands much quicker than we humans. The Viper felt about like a F-111 down low on a bumpy day. Nice soft ride for a "light" jet.

Waiting for the recorders' story.

[slats11]

Svarin (http://www.pprune.org/members/302454-svarin)
Gentlemen,

it is obviously difficult for most internet-age people to read beyond a few lines of text with any effectiveness

With all due respect, I don't think this is really fair. All of us have been generous with our time and contributed what expertise we have in order that we may collectively understand what happened here.

Naturally, we will all tend to focus on different aspects and different phases of this disaster - depending on our area of special interest or expertise. When all you have is a hammer......

Clearly you have detailed understanding of the flight control systems and the ACARS stuff - areas that are pretty much meaningless to me. Others have displayed very detailed understanding of radio capabilities and satellites. It is not that I am disagreeing with any of these people, or not bothering to read their posts (interesting even if beyond my understanding). I am simply talking about something different.

So I am not disputing your proposed explanation - I can't. Rather, I am proposing that there are likely to have been additional significant human nature issues prior to the upset, and that these may have played a contributory role.

The fact that this scenario has never happened previously despite many hundreds of thousands of operation of this model aircraft, and the fact that we still don't really know what has happened despite thousands of posts and countless thousands of hours of speculation means that the exact sequence of events is likely to be complex and non-intuitive. There is likely to be a complex interplay of factors (aircraft and personnel) that combined on this particular occasion to produce a unique outcome.

Please, this is not a pissing contest. Nor should it be seen as an opportunity to denigrate others. Surely that is disrespectful to those that lost their lives, as well as to those here seeking to advance our collective knowledge. When (if) we know all, then it may appear to have been somewhat arrogant or naive to believe that there was one single factor (to the exclusion of everything else) responsible here.

[HazelNuts39]

CONF iture;

RE jcjeant's question;

BEA report no.2, after analysis of thirteen events of losses of or temporary anomalies in indicated speeds, states:
In seven cases, the autopilot was reconnected during the event. In two of them, the re-connection occurred when the two speeds were consistent with each other but were erroneous;and:The reappearance of the flight directors on the PFD when two air speeds will be calculated that can lead the crew to rapidly engage the autopilot. However, these speeds, though of the same order, can be erroneous and weak and thus lead the autopilot to command movements of the flight control surfaces that are inappropriate for the real speed of the airplane.

[Machinbird]

...can be erroneous and weak and thus lead the autopilot to command movements of the flight control surfaces that are inappropriate for the real speed of the airplane.

For those that remember the X-31 accident previously provided as a reference, does this sound familiar?

[Khashoggi]

Machinbird, thanks for the reference...

X-31 airdata icing fubars the flight computer.
X-31 Crash (http://www.check-six.com/Crash_Sites/X-31_crash_site.htm)

Looks like a pancake (~low[non-existant] horizontal component, large vertical, minor yaw from FL200 to Edwards) to me:

http://www.check-six.com/images/Crash_Sites_images/X-31/X31-95Aerial.jpg

[grizzled]

slats11...

Well said.

[Svarin]

I said :

it is obviously difficult for most internet-age people to read beyond a few lines of text with any effectivenessslats11 said :

With all due respect, I don't think this is really fair.You are right. It was not. I regret it came across as a personal slight. Please accept my apologies.

I read your post in full by the way :O

[henra]

svarin:

02:14:20 - .1/FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

The failure has AFS (Auto Flight System) as its identifiers. AFS is Airbusese for Autopilot. But wasn't that A/P OFF at the beginning of the sequence ? And it was turned OFF by the aircraft itself, following Pitot probes failure. And now we find it as the identifier in an FMGEC fault, which means AFS detected a fault in FMGEC1. Who turned the A/P back ON and reactivated it ?


Good catch !!

Obviously this message never received the attention it maybe warranted..

Even looking at BEA's comment on this item reading a bit between the lines it becomes clear there might be something to it:

From BEA's second interim Report:

FMGEC1 (1CA1) (2 h 13)
ATA: 228334
Source: AFS
Identifiers: -
Class 1, INTERMITTENT
This message cannot be the trace of a reset which, in particular, excludes the
possibility of a manual shutdown. This message could be the consequence of
inconsistency between the two channels in the FMGEC (COM and MON). Such
an inconsistency could be the consequence of erratic input parameter values.
In any event, the effects of such a message could only be the disengagement
of automatic systems, whose associated cockpit effect messages had already
been transmitted at 2 h 10.
The “INTERMITTENT” nature of the message means that the problem lasted for
less than 2.5 seconds.


Between the lines I read that this indeed seems to indicate that automatic systems have been disengaged. Which in turn could imply they had been re-engaged before after the first disengagement which triggered the 210 ECAM's.
The AD might indeed closely be related to this accident.

The ACARS message regarding Cabin Vertical speed is dated 1 min later than this. Which would mean that they were most likely not at CRZ altitude when the AFS was potentially re-engaged.
This would point indeed to two upsets:
Initial upset caused by UAS, recovered at an intermediate altitude (soemwhere between 10000 and 20000ft) which matches previous UAS incidents quite well btw.
A subsequent upset caused by the AFS mislead by the still unreliable but now consistent speed.
Question arising from this scenario: Down to which altitude could pitot icing be expected?
Anyway, this scenario could explain the tragic difference to the previous incidents.

[Svarin]

Regarding this message :

2:14:20 FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

BEA reported :

In any event, the effects of such a message could only be the disengagement of automatic systems, whose associated cockpit effect messages had already been transmitted at 2 h 10To this should be added, from the same report, that a cockpit effect will only appear once in a given CFR/PFR. What we deal with is a CFR (Current Flight Report). I take it then that a A/P OFF message will not be repeated, since it was sent around 0210.

It is unfortunate that BEA would only give this item of information in that particular, obscure way. They essentially repeat themselves. However, reading between their lines would mean that A/P went OFF again without an ACARS message being transmitted (already done). So A/P had to be turned ON after 0210.

Another information hidden in this sentence from the report is that the list of cockpit effects produced by this failure is included in (but not necessarily identical to) all cockpit effects already sent from 0210.

In addition, would AFS catch a fault in FMGEC if it was still OFF (kicked off by the system itself). In other words, does the AFS as identifier positively ascertain that A/P was ON at the time the message was concatenated ?

My answer is yes, through all accumulated knowledge, but I do not have a positive answer, officially written in a book. I believe yes, it fits with all the rest (and I mean all the rest), but then... I am not defending that case in a court of Law, lucky me.

I would have expected BEA to answer that particular question, one way or the other. I guess they will do it now, and prove me wrong...

(Simultaneous with henra)

[Chris Scott]

slats11 & Mr Optimistic,

Been de-camping for last 48hrs, so now trying to catch up with this freight-train again... You've been discussing cabin crew activity/position.

Of course they MIGHT have been recently dealing with pax dinner. 0200z is 2200L at Rio. They were 3hrs30 into the flight, but it was a big load. If pax finished, crew dinner (cabin and/or flight-crew) might have been still under way.

[Just as an aside, I was once served dinner on an A320 and, as the steward lost his balance, the meal tray collided gently with the throttles. No harm done until he panicked and whipped the tray backwards, depositing its contents (including curry & rice) all over the centre pedestal!]

It can take the CC a long time, from the receipt of a command to secure the cabin, to complete the task. The most compelling evidence I've seen that they had not completed that task was the excellent picture posted by Shadoko, here (http://www.pprune.org/tech-log/395105-af-447-search-resume-190.html#post6406232), of one of the galley catering-cannister stowage units. The latches that must be closed to secure the cannisters are plainly open. Any proximate cabin crew member worth his/her salt would have secured them before sitting down, if severe turbulence was expected.

[Mr Optimistic]

CS: OK, thanks. Seems clear on that point at least!

Edit: Though I wonder if that is consistent with the early best-fit scenarios with the weather, ie that the a/c was at the far end/about to exit a Cb. Suspect that can't be right as there would have been warning before the 'event'.

[CONF iture]

HazelNuts39,

Thanks for the references from the BEA report, I didn't remember them.
Still, I think the AD is more specific :
However, in some cases, the AP orders may be inappropriate, such as possible abrupt pitch command.
Are you aware of such specific concern among the 13 events ?
Why that AD so late (DEC 2010) when the 13 events were already known for a while ?
Any possibility for another ... event to justify the making of such AD ?

I'm not sure what to make of "c", (in the sense that I would have expected not a pitch angle protection active, but an AoA protection active input.
I don't have an answer to that question, but that reminds me the 'Anti pitch-up compensation' which was partially responsible of the QF72 upset.
Who was aware of that 'compensation' ... before it was mentionned in the ATSB report ?
I had personaly never seen anything on it in any FCOM or other VACBI.

Just to say that there is so much unknown or/and untold on those airplanes ...

[Pugachev Cobra]

UAS due to icing in the Kiel probe causes X-31 flight computer anomaly.

YouTube - X-31 Crash Segment from "Destroyed in Seconds"

In case someone haven't seen it yet.

The 43-minute mission was nearing its conclusion when ice began forming on the X-31's pitot tube. The ice caused incorrect airspeed information to be sent to the craft's flight control computers, which were responsible for reconfiguring the aircraft for lower speeds. The result was a series of sudden, uncontrollable oscillations in all axes. The aircraft then pitched to 90 degrees angle of attack, and Lang was forced to eject as the X-31 crashed near the northern boundary of Edwards Air Force Base.
From: NASA - Dryden Flight Research Center - X-Press: January 2004 (http://www.nasa.gov/centers/dryden/news/X-Press/stories/2004/013004/new_x31.html)

[grizzled]

CONF...


Just to say that there is so much unknown or/and untold on those airplanes ...


If the DFDR and CVR are retrieved and readable, when all is said and done your words may seem prophetic.

[jcjeant]

Hi,

The latches that must be closed to secure the cannisters are plainly open. Any proximate cabin crew member worth his/her salt would have secured them before sitting down, if severe turbulence was expected.

That's a very good interpretation of this picture .. good deduction
As a VFF I fly in many parts of the world ... nice aeras and bad aeras ..
I experience more than enough very bad turbulences .. (mainly at the same aera of the AF447 path and also in Asia and India aeras)
Those very bad turbulences never come suddenly but gradually .. for finish in a apotheosis (rice on the ceiling .. etc .. :) )
So .. what about a foolish speculation .. that in fact ... AF447 was not in very bad turbulences at the time of the event ???

[Svarin]

jcjeant wrote :

So .. what about a foolish speculation .. that in fact ... AF447 was not in very bad turbulences at the time of the event ??? Concur.

Turbulence not necessary to explain LOC in this instance.
CB inadvertent penetration not necessary either.
Less than awake crew not necessary either.
Experience not an issue (test pilot experience maybe).

All of this an opinion, formed after extremely detailed and careful study (by several knowledgeable people). But then, it must be wrong, or else...

[DozyWannabe]

Just to say that there is so much unknown or/and untold on those airplanes ...

On most modern aircraft if we're honest, CONF... Even venerable airframes like the 737 have, in their latest incarnations, developed some previously unknown behaviours (such as the Radalt/Autothrottle problem highlighted by the Turkish Schiphol accident). The manufacturers do tend to know about them, but they rarely if ever publicise them until they're absolutely sure they know what it is.

As such I hope some usable data can be extracted and we can finally get some answers rather than the ring-around-the-roses we've been having on the subject for the last couple of years...

[DingerX]

Maybe I'm missing something -- and it was quite a while ago that the ACARS messages were picked through --, but I read this:


In any event, the effects of such a message could only be the disengagement of automatic systems, whose associated cockpit effect messages had already been transmitted at 2 h 10

as meaning that the message refers to the same event, and the time difference is due to the relevant priorities of messages waiting to be transmitted.

[GerardC]

So .. what about a foolish speculation .. that in fact ... AF447 was not in very bad turbulences at the time of the event ???
Imho, this is NOT "foolish speculation", it is just plain evidence.
Consider these two points :
- read the LH crew (on the same route a few minutes earlier) statement : standard ITCZ crossing routine ;
- obviously, the "fasten belt" sign was "OFF" : hence the number of bodies recovered (SLF and CC), galley condition etc.. ;

all this suggests that the ride was not too rough.

'Captain's rest' is rostered and taken as rostered in some companies which I find bizarre!
From what we have here, (a routine ITCZ crossing), there is, IMHO, nothing "bizarre" with the captain having his rest time.
F/O's are fully qualified to deal with this kind of event.
If the captain MUST be on the F/D each time bad weather is forecasted, then why bother with R/P ?

About sleepiness in the cockpit :
It is hard to escape the conclusion that these guys were caught out somehow. Despite a significant weather system in their path. And despite (I presume) a degree of radio traffic that other aircraft were diverging from their track.
Once you have completed your selcal check with the ATC in charge, you have NO "degree of radio trafic" for weather deviations by other A/C.
Requests and clearances go through HF, which you do not monitor, or through CPDLC.

[bearfoil]

Finally some scepticism of the urban myth that is this thread. Let us hope it will extend into the work of those whose "report" is sacred.

"Two highly qualified pilots, experienced and familiar with the route, flying a first rate ship for a flag carrier...."

My bias has been clear, and I am unrepentant. There was a structural "event", the computer got confused, or the a/c was rendered in some way uncontrollable, and not by the pilot(s).

UAS is patent in this family of a/c. Difficult recoveries are as well. Perpignan, and Asseline's wreck. The a/c is notorious for making a smooth recovery from UAS difficult (EASA AD).

In my firm opinion, almost all of the proffered evidence skirts the issue.

[promani]

GerardC

If I was the captain, I would probably have had lot of confidence in my buddy in the RH seat as he had more experience on the SA route, 39 rotations against my 16. But I think I would have liked to take a peek at the Wx before taking a nap. I would also have expected him to listen in to other traffic, especially those ahead of us, on 121.5 or whatever.
The third guy, had the least experience of all, and it was suggested that he moved into the LH seat when the captain left. Is that significant?

[Graybeard]

Just last night got around to watching PBS NOVA "Crash of Flight 447," which aired on 20 Feb. There seems to have been considerable discussion of it, judging by snippets, but there must have been a lot of it at the time, (now page 138 of prior thread) censored by the mods, as there are incomplete references and very few posts about then. That is disturbing.

Nova tried to explain the events leading up to the crash. I'll address only the Wx radar here.

Their expert, from NCAR part of NOAA, said the Wx radar on AF447 had only 50 mile range. Strike one. It's 320 miles, if the storm is dense enough to matter.

Nova showed a small/medium sized cell in the plane's track toward the major line of storm. Nova said the small cell would obscure the radar view of the major storm, causing them to stumble into it.

Poppycock/BS/Howash! The Wx radar on 447 returns were calibrated for rainfall intensity. When the intensity of return is high, an algorithm called "Path Attenuation Compensation" kicks in to assure calibrated display. When the storm is too intense for penetration without reserve to see the full picture of the "storm behind the storm," the Wx radar puts up a yellow band, called PAC Alert, at the outer range ring of the display.

I have great respect for Public Broadcasting in the US, but this program failed miserably. I wonder if major sponsor, billionaire David H. Koch, didn't have too much editorial input?

[gums]

Salute!

I tend to agree with Bear. The opinions of Svarin and Jct are ones I also agree with.

I only post here as I was flying FBW systems before most, if not all folks here. Try 1979.

We can talk about all the ACARS transmissions and speculate on ocean currents and such, but the cause of the crash is clear to this old pilot - loss of control.

Richard Bach placed it like that - loss of control due to factors beyond human control, or big pieces coming off the plane or control linkages freezing/breaking. etc.

We can sort out the ACARS messages later, once the recorders are recovered, particularly the CVR. I want to know/understand what in the hell did the crew do? What did they see/feel?

The chance that pitot-static air data became unreliable is high. And as SV and JC pointed out, it's possible to have the phenomena occur well before entering turbulence. Hell, the X-31 had a problem in the clear, blue skies over California.

I shall be the last pilot here to blame the crew. If they encountered conflicting indications that things were going south and could not react in time, then the rest is history. Loss of control.

I do not subscribe to the theories that loss of control surfaces or other "parts" were the cause of the crash. Parts may have come off well before impact, but that was just part of the sequence. What in the hell happened at the beginning? Go see the Columbia loss data. Things were happening well before the thing came apart. The crew was unaware, and if they knew then they prolly couldn't do anything except pull up slowly and then bail when at a lower mach/altitude. They didn't know, but last transmission was the beggining of a question by the Commander that was cut off.

Of particular interest to me is the sequence of "reversion" of the flight control system when something bad happens. The Airbus does not have the same sequence of reversion modes that the F-16, B-2, F-22 and Shuttle have. Those planes focus upon crew control for a vastly different mission than commercial airliners, and have few modes that use nav data and approach/takeoff/go-around/cruise to "help".

[RR_NDB]

We can separate Researchers, Engineers, Designers, and Technology Professionals in two groups:

One, the people that think a lot before implementing something and always uses an Strategy (from the Greek military commander Stratego that before the battles always had a well made plan). This group normally have SIMPLE SOLUTIONS for complex things.

Kelly Johnson used this approach to design THE ANGEL, capable to fly near the coffin corner, implemented in just 80 days.

He used the Keep It Simple Stupid approach for the U2 R&D and it´s implementation.

The other group uses the Keep it Complex Stupid approach. And at pressure from the bosses deliver anything...

Let´s imagine the scenario of:

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
3) Had pitot´s blocked.
4) Entered unusual attitude.
5) Stalled and descended at unusual attitude.
6) Eventually leveled (almost) and hit surface

Question:

Is that model too simple?

Finger crossing to locate FDR/CVR and be readable.

Wht´s lacking in this analysis?

[henra]

as meaning that the message refers to the same event, and the time difference is due to the relevant priorities of messages waiting to be transmitted.

I doubt it. The ACARS Message was timestamped 213 as opposed to the initial one which was following the ECAM messages. They were timestamped 210.

Somewhere in the old Thread we learned that once an ECAM message has been posted it will not be sent again. Therefore the original message for disconnection of AP / A/THR was not repeated even if it occured a second time.

This points to a separate action i.e. potential re-engagement and second automatic disconnection of AFS.
This concides timewise with the loss of ACARS signal and the Cabin Vertical Speed advisory, which points to a severe (second) upset following/connected to this potential second disengagement of Auto Flight System(s).

The sequence could indeed match to the scenario mentioned in the AD.

[henra]

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
3) Had pitot´s blocked.
4) Entered unusual attitude.
5) Stalled and descended at unusual attitude.
6) Eventually leveled (almost) and hit surface

Question:

Is that model too simple?



From my point of view the general chain of events as described is quite likely pretty close to what happened in broad terms. Much of the discussions here revolve around the details behind.
E.g. :
- Why did they fly into the weather ?
- Why didn't the manage to keep it flying using Pitch&Power ?
- Why didn't they recover within 35000 ft of altitude ?
- Did automatic flight controls play a role in the upset/Non-recovery ?

And those are for me the really intriguing questions begging for answers by the FDR /CVR.

[Graybeard]

Back to the discussion of why the ACARS wasn't consulted first when the plane was overdue:

I remember reading early on that Maintenance in CDG noted the Airspeed fails reported by ACARS, and moved the plane that was AF447 up in priority to get the new pitots upon arrival.

It would be easy enough to automatically alert company Dispatch whenever a Flight Essential or Flight Critical component were flagged over ACARS. Also, maybe the ACARS should be programmed to transmit every minute as long as there is a Critical component flagged as failed?

Regarding Satcom vs. HF data transmission: the link is error-free, when it's working. HF works everywhere beyond VHF range, and is pennies to dollars less expensive than Satcom. HF continues to evolve, and a major data rate improvement was announced recently by Collins.

[RR_NDB]

Ok, let´s look at each point:

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
3) Had pitot´s blocked.
4) Entered unusual attitude.
5) Stalled and descended at unusual attitude.
6) Eventually leveled (almost) and hit surface

1) Several possible reasons:
a) Radar in auto mode. The best is to adjust manually the antenna elevation to characterize better the pattern ahead.
b) Shadow from first CB area (as PBS suggested)
2) n/c
3) A fact
4) A very probable fact as per ACARS msg´s
5) The same of previous point
6) A fact

Finger crossing to locate FDR/CVR and to be readable.

Thanks for replying, Rgds

[CONF iture]

On most modern aircraft if we're honest, CONF... Even venerable airframes like the 737 have, in their latest incarnations, developed some previously unknown behaviours (such as the Radalt/Autothrottle problem highlighted by the Turkish Schiphol accident). The manufacturers do tend to know about them, but they rarely if ever publicise them until they're absolutely sure they know what it is.

That's not a secret that the Airbus is more automated and 'protected' than any others ...

Try a similar Radalt malfunction with the 320, it won't only interfer with the A/THR but also with the Flight Controls !
Very interesting to study.


Once you have completed your selcal check with the ATC in charge, you have NO "degree of radio trafic" for weather deviations by other A/C.
Requests and clearances go through HF, which you do not monitor, or through CPDLC.
Clearance - No clearance - we take the deviation we need - The information on the weathear deviations will be broadcasted or/and monitored directly on VHF 123.45 that everybody should syntonize ... unless I'm wrong and the appropriate frequency is different in that area (?)

[lomapaseo]

Graybeard

I have great respect for Public Broadcasting in the US, but this program failed miserably. I wonder if major sponsor, billionaire David H. Koch, didn't have too much editorial input?

I wouldn't go so far into wondering.

Programs like this are conceptialized based on written reports, various experts contacted, scripts written against what some experts postulate, then deeper experts are consulted for support or refute. Then talking heads that can explain a theory that the script is written against are asked to explain during filmng.

They were ammendable to making changes in their script if a talking head can't support it.

Just like with PPrune you have to be able to read between the lines to comprehend its veracity

[Graybeard]

RR_NDB
Ok, let´s look at each point:

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
...

1) Several possible reasons:
a) Radar in auto mode. The best is to adjust manually the antenna elevation to characterize better the pattern ahead.
b) Shadow from first CB area (as PBS suggested)


1 a) The Wx radar on 447 did not have auto tilt. They had the Collins WXR-700, not the newer WXR-2100.

b) As I explained in detail above, it was not possible for the major line to be shadowed by the intervening cell. In this case, PBS "expert" was a ground radar guy. Rockwell Collins, the maker of 447's radar, was not listed in the credits. If RC didn't want to get involved, they surely could have referred Nova to a knowledgable source.

Here are some possibilities:

1. The storm did not look bad enough to deviate around.
2. The line of storms was so long and uniform, it would not seem to matter where they penetrated.
3. The pilots did not have enough training in Wx radar ops.
. a. Nobody was looking at the radar returns.

[bearfoil]

From the ACARS and some great data via PJ2, and others, the a/p drops involuntarily when Law reverts 'out' of Normal to ALT. The Attitudes from the a/c computer that would cause the a/p to drop on its own when exceeded are here also. I recall that this a/c will not re-enter NORMAL out of ALT1/2 or DIRECT unless and until the ship has landed, and can be indexed (I think). So if from ACARS the a/p dropped by command from (Computer) ADIRU disagree, then I can't imagine why auto would be allowed to re enter the room even if invited.

Likewise, if DIRECT was attained, and RTLU and other minimum protections were operating, I can't easily imagine this accident happening unless something additional occurred (Svarin's nifty catch). The first and most likely candidate would be a/p trying to horn in after teasing the front with reacquired Bars and a less than sixty second a/s agree 2x2. But the pilots would know that NORMAL LAW is u/a, so why try to latch a/p only to see it booted (rejected) by the computer again??

Less likely, but possible, attitude excursions were attained that exceeded the a/p working limits and this caused the drop?

Less likely still, accompanying attitude extremes were disparate airstreams transiting the static and pitot ports which may have caused the TCAS and Windshear bunk that got sensed, as well as (actual) corrupt airdata??

These attitude extremes would be Wx and causative of UAS? Then, as the pilots recovered from UAS, abrupt and mechanically incoherent Pitch commands caused upset??

Too fanciful.... UAS, recovery, then the activity addressed by the (too late AD).

The more I try to understand this a/c's LAW, the more senile I believe I may be.

[promani]

Graybeard

1. The storm did not look bad enough to deviate around.
2. The line of storms was so long and uniform, it would not seem to matter where they penetrated.
3. The pilots did not have enough training in Wx radar ops.
. a. Nobody was looking at the radar returns.

1. The storms were bad enough for the flights before and after to deviate
2. Then why not return to Brazil
3. I think that 39 SA rotations since being in the A330/A340 division is sufficient to be able to use the Wx effectively
3a. No answer to that possibility.

[JD-EE]

ALCS65, they went down 400 miles from Natal (which I'd half expect to be VHF ACARS equipped and 160 miles from Fernando de Noronha (which might be ACARS equipped.) They were pretty much out of VHF communications for quite a period of time. Off hand I cannot find a reference to either of them supporting ACARS. I'd estimate they were a good hour out from any meaningful VHF contact, maybe (much) more. I'd expect the cut over to satellite would happen at or some modest time after the switch from VHF flight control communications to HF.

Released documentation reports the last several position reports as well as the standard ACARS all, they say, through Inmarsat's AOW bird.

[kilomikedelta]

I get the impression that some commentators here are making the assumption that HF/VHF/UHF radio signals from AF447 would have been equivalent to that of trailing a broadband internet cable behind the aircraft.

Radio amateurs would love to have an antenna 40,000 feet up in the air but realize that in the midst of an electromagnetic storm, signals even 500 metres away might be unintelligible to a receiver due to noise, propagation anomalies and polarization rotations regardless of error correction protocols even if one is dumping the full American 1.5 kW into the ether.

Does anyone know if the QRN at the critical moments of the AF447 flight obliterated RF communications or whether the sequence of the ACARS messages was affected by poor reception?

[auv-ee]

I have great respect for Public Broadcasting in the US, but this program failed miserably. I wonder if major sponsor, billionaire David H. Koch, didn't have too much editorial input?

One might fault PBS for repeating without independently checking, but that was originally a BBC production broadcast in the UK on 2010/05/30. I believe it was re-narrated (different accent of narrator) and possibly re-edited for the PBS release on 2011/02/16.

[CogSim]

1. The storm did not look bad enough to deviate around.
2. The line of storms was so long and uniform, it would not seem to matter where they penetrated.
3. The pilots did not have enough training in Wx radar ops.
. a. Nobody was looking at the radar returns.


I believe 1., 2. are more likely than 3. or 3a. The whole WX deviation thing may be a red herring. In the animation that PJ2 posted, we can see the ELY flight flying without any deviations. In fact, it looks like it flew through a cell comparable to the one AF447 is projected to have flown into.

I think AF447 was unlucky to have entered a UAS condition. (quite independent of weather conditions.) AF knew this was always a possibility, no matter how remote. Hence, the pitot replacement program.

Two other possibilities I'd like to add to the above list, if I may:

4. Crew noticed something anomalous with airspeed and were fixated on understanding the situation.

5. Crew noted the weather ahead but deemed it a lower priority issue than something else. (If so, what is the USD 64K question)

But the pilots would know that NORMAL LAW is u/a, so why try to latch a/p only to see it booted (rejected) by the computer again??

Could this be the last actions of a crew desperate to get out of it...

[mm43]

Most of Brazil is covered by SITA/Datacom VHF ACARS, and the eastern corridor is completely covered. This coverage extends to a station located on the offshore island of Fernando de Noronha (SBFN). The ACARS frequency is 131.55MHz, and this coverage was in place at the end of 2008.

AF447 was in range of the SBFN secondary radar until about 250NM or about 10 minutes after passing INTOL. With an omnidirectional 3dBi VHF antenna at SBFN, reliable data comms should have been achievable to at least 180NM with the a/c at FL350.

[kilomikedelta]

"With an omnidirectional 3dBi VHF antenna at SBFN, reliable data comms should have been achievable to at least 180NM with the a/c at FL350."


In HF/VHF/UHF in the middle of a Cb?

[ACLS65]

ARINC assumes a coverage of about 245nm for an aircraft at FL300. Both Natal (NAT) and Fernando de Noronha (FEN) are ACARS RGS's, but I put NAT at 590nm and FEN at about 420nm.

It does look like AF447 would have passed through several VHF ACARS sites prior to being out of range. Still hoping someone with first hand knowledge can comment on whether the VHF to SATCOM ACARS switch happens automatically as mentioned in the manual, or if maybe on a flight on this route it just uses SATCOM the whole time.

RGS List:
RGS list (http://datalink.sas.se/ground/rgs.html)
(Note: Not a complete list.)

Map:
http://datalink.sas.se/ground/images/sita_eumea.pdf

ALCS65, they went down 400 miles from Natal (which I'd half expect to be VHF ACARS equipped and 160 miles from Fernando de Noronha (which might be ACARS equipped.) They were pretty much out of VHF communications for quite a period of time. Off hand I cannot find a reference to either of them supporting ACARS. I'd estimate they were a good hour out from any meaningful VHF contact, maybe (much) more. I'd expect the cut over to satellite would happen at or some modest time after the switch from VHF flight control communications to HF.

Released documentation reports the last several position reports as well as the standard ACARS all, they say, through Inmarsat's AOW bird.

[JD-EE]

Thanks for getting me to dig into the books again, mm43. Yes, tangential range is 300 miles or the equivalent in nm. Intelligibility would likely suffer some at about 200 miles. They were easily out of communications for some time before things pickled.

[JD-EE]

kilomikedelta - at 200 miles out they were not in a storm. That came up 200 miles further on. And the map I checked distances on had the LKP mislocated. They had it south rather than north of the equator. Teach me to double check things rather than wing it.

[gums]

Salute!

Too much about ACARS and WX radar on the jets. And times for ACARS data not correlated with the flight recorders yet.

As Cog pointed out, at least one other plane flew thru the wx.

SOMETHING happened and the result was loss of control. I do not blame the crew.

I have flown thru the ocean CB's and they are nothing compared with a big CB over Kansas, USA. Whatever happened was before penetration of a line of storms. I use the Captain's body recovery to make the point that "things were going well until......"

Before I quit posting here for awhile, I shall bet that some sensor or input to the flight control system went haywire and the crew could not figure it out in time to do something constructive. My God, I just went thru the tech order for the jet and it is layer upon layer of inputs to the control system. Sheesh. Despite the plane's basic aero stability compared to the military jets that have FBW, it looks like even the most basic control laws still use many inputs from sensors. And some of those could be FUBAR.

The CVR will be more revealing than the basic flight data recorder, IMHO.

What did the crew see?

What were the flight conditions? When things went south, what was the environment? Were they pitching up and down and rolling left-right? I don't think so or the Captain would have been back in the cockpit.

SOMETHING happened before encountering the storms. The ACARS transmissions will soon be correlated with the flight recorders. We may be able to paint a picture of the final minutes or seconds. Findings will help to prevent another occurrence.

Although the Columbia breakup did not capture much crew talk, the flight dynamics were faithfully recorded. That tragedy took place very quickly despite indications on the recorder that something was terribly wrong 4 or 5 minutes beforehand. The crew didn't know, but at the last transmission they wanted to ask about something versus tire pressure in one of the wheels that the ground control was interested in.

sorry for the rant, and will stay silent for a bit.

P.S. The IAF guy on board Columbia was a student of mine in the F-16. I have a patch from that IAF bunch, and the IAF only sent one small group to check out in the first operational FBW jet in the world. So I have a special interest in incidents involving FBW planes, having been one of the first to fly the damned things.

[RR_NDB]

Hi, KMD this is CW, :hmm:

With the proper selection of QRG (band) HF would be VERY RELIABLE even with high QRN and the poor current HF antennas.

I NEVEER lost a QSO in several thousands hours of HF operation using 200 W out sometimes lowering to 1.8 MHz (phone) due severe QSB.

In just one case due a VERY STRONG WX System i faced almost complete blackout of powerful MW BCST STN 80nm from my PSN but this is RARE.

I don´t believe, based in ACARS msg´s, they tried to use comm, HF or other.

They should be looking to other priorities.

The info on QRN at the night i think was lost and i think was not a factor.

On good antennas look at the trailing wire (30,000 ft) used by the 707 of USN for VLF to subs.

Unfortunately the current HF antennas are VERY POOR.

[deSitter]

A working scenario is - the FMC disables the autopilot because of unreliable airspeed measurement by the clogged pitot tubes. Once that is done, it should not be possible to re-engage the autopilot manually. Since that apparently did happen, the implication is that the crew re-engaged the autopilot after some initial upset, and this played right into the trap that was mentioned by the recent AD. The crew think they have recovered, and instead they have guaranteed the worst sort of stall, a flat spin basically.

So all talk about being asleep and weather and all that is just not relevant - because the problem here was systemic, even down to the over-reliance on programming instead of piloting. Ok that was a speculation.

[mm43]

JD-EE;
Yes, tangential range is 300 miles or the equivalent in nm. Intelligibility would likely suffer some at about 200 miles.260NM and 174NM.

[Graybeard]

RR_NDB: Unfortunately the current HF antennas are VERY POOR.



What basis do you have for that statement, Mac?

[slats11]

Appreciate the apology Svarin - accepted.

OK. If I understand correctly, several of you are thinking:
1. Initial UAS leading to upset, leading to loss of AP
2. Manual recovery
3. Re-engage AP - at a lower altitude and several minutes later
4. Catastrophic LOC due to inappropriate pitch up issue covered in recent directive.

Now if you had a significant upset followed by a recovery, would you not expect over a period of some minutes:
1. Some form of radio communication
2. Pax and CC secured

Or do you suppose that the initial upset was sufficiently violent that anyone not secured was incapacitated (and stayed unsecured)? In which case, would the pilots really try and re-engage AP having gained a degree of manual control?

Am I misunderstanding you all here?

[Mr Optimistic]

'But the pilots would know that NORMAL LAW is u/a, so why try to latch a/p only to see it booted (rejected) by the computer again??'

So if it couldn't/didn't get the a/p back, what was Svarin's ACARS message about ?

[Machaca]

1. Initial UAS leading to upset, leading to loss of AP
2. Manual recovery
3. Re-engage AP - at a lower altitude and several minutes later
4. Catastrophic LOC due to inappropriate pitch up issue covered in recent directive.

That's one possibility according to the AD.


The other is:
1. Initial UAS leading to upset, leading to loss of AP
2. Manual recovery
3. FD bars re-appear
4. Catastrophic LOC due to following FD orders

[Svarin]

Gentlemen,

here is my own offer of a scenario sequence. All of this to be taken as an opinion. I would not bet my life on it, but it is the best I could come up with, with great outside help :

1 - high altitude ice crystals (outside CBs but inside thin layer of high altitude clouds around them - red returns on infrared satellite pictures).
2 - ice crystals block pitot probe drainholes (over-reading of IAS)
3 - Unreliable airspeeds -> A/P kicks OFF, along with other stuff
4 - a nasty invisible trap is set through FCPC2, no notice to the crew
5 - crew recovers from UAS without any upset
6 - UAS appears over, F/D bars reappear (see AD)
7 - crew reengages A/P, thinking the problem over
8 - trap is sprung, A/P kicks OFF again in violent upset (hard pitch-up)
9 - upset is not recoverable or not recovered (I expect 99.9% of airline pilots to fail that one)
10 - upset ends up as a deep stall or slow spin to the surface

This means the a/c likely did not crash right after end of ACARS sequence. The Cabin Vertical Speed message looks (to my opinion) like a consequence of FMGEC1 fault triggering a CPC reset or change of configuration, not a real descent (other messages exist for relief valves and other conditions).

Comments, questions and counters welcome.

[HazelNuts39]

I've been trying to imagine the mechanism by which re-engagement of the autopilot at corrupted airspeed would cause a violent upset. The AP controls altitude, so the first assumption one needs to made is that the altitude at re-engagement differs from the selected altitude. Let's assume it is lower. The AP will then command movement of the elevator control to initiate climb to capture the selected altitude. The AD suggests that the initially commanded movement of the elevator could be too abrupt when the real speed of the airplane is much greater than what the AP 'thinks' it is. The response of the airplane would then be more abrupt than what the AP is trying to achieve, which is, I suppose, a schedule of vertical acceleration and vertical speed. Wouldn't the AP adjust its command before it results in an uncontrollable attitude?

[SaturnV]

Goodness.

ELY 010 was on a parallel track to AF447. AF 447 was on Airway UN873. ELY was on UN866, over 100 NM to the west.

[mm43]

Svarin;

But that doesn't explain without an initial UAS upset why the aircraft finished up so close to the LKP even if it did enter an unrecoverable stall following the attempted A/P reset.

The only thing we positively know at this time is at the nominal 0210z AOC report, the aircraft was west of the track. This probably occurred within 30 seconds of the report and not as a premeditated crew action. Unless of course an over-speed event was already occurring, and the heading of the a/c could have been anywhere.

So in 5 minutes the a/c would appear to have gone effectively nowhere. Methinks there must have been more than one upset. In that respect only, your scenario doesn't quite fit, though I am keen to hear a better explanation.

[HazelNuts39]

FMGEC1 fault triggering a CPC reset or change of configuration, not a real descent (other messages exist for relief valves and other conditions).The CPC commanding a change of cabin pressure exceeding 1800 fpm during 3 seconds? Which other messages (cockpit effect or FLR) exist?

[Bobman84]

So it's the 25th of April now, not far from 26th.

Any updates in regards to the recovery vessel's position?

[rotor12]

The last position :
Carte en temps réel des navires - AIS - trafic maritime et positions (http://www.marinetraffic.com/ais/fr/default.aspx?oldmmsi=226235000&zoom=10&olddate=4/24/2011%201:06:50%20PM)

[mmciau]

IIRC the Craft should be near station on 26 April .

[thermalsniffer]

Svarin

How do the prim and sec faults layer into your scenario?

Stated differently, does AP re-engagement come before or after these messages?

Thanks.

[GerardC]

Clearance - No clearance - we take the deviation we need - The information on the weathear deviations will be broadcasted or/and monitored directly on VHF 123.45 that everybody should syntonize ... unless I'm wrong and the appropriate frequency is different in that area (?)
You are right, we ALL take whatever weather deviation is needed, AND (preferably before deviating...) we send a message (HF or CPDLC) : "request deviation up to XX Nm due to weather".
Do not forget these routes are not as crowded as the NAT OTS area : after dozens of SA crossings (before and after AF 447 crash), I can't remember of much (if any) "deviation" chat on 123,45 (or 121,5).

Concerning the questions about ACARS transmissions, sorry, I fail to understand the point : as long as the system is in VHF range, ACARS goes through VHF (as it is much cheaper). When out of VHF range (or if no VHF network exists), the system switches automatically to SATCOM without any crew action.
You get F/D alert messages :
- in VHF range, if you move VHF frequency out of the "DATA" position ;
- out of VHF range, if satcom is lost.

HF data transmission works fine for RA (or pleasure boats email traffic).
At the moment (and in the near future), it is not used (or planned to be used) for commercial aviation.

[Svarin]

thermalsniffer wrote :

How do the prim and sec faults layer into your scenario?Here we need to refer to the MEL, where a procedure is outlined for a PRIM1 dispatch, or a SEC1 dispatch. In both cases, a fault message appears on ECAM 30 seconds after engine start. Let us assume then that a PRIM1 or a SEC1 turned OFF for whatever reason will trigger an ECAM message 30 seconds later (some kind of self-check or whatever it is FCCs do in these situations)

Let us then examine closely the timing of 3 ACARS messages :

2:13:45 WRN/WN0906010213 279002506F/CTL PRIM 1 FAULT
2:13:51 WRN/WN0906010213 279004006F/CTL SEC 1 FAULT
2:14:20 FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

FMGEC1 is a FLR message, its correlation window opened one minute before transmission, minus 5 seconds for ACARS sending, thus : 02:13:15.
PRIM1 FAULT and SEC1 FAULT are cockpit effects, but then let us factor in the 30 seconds delay as above. This gives a time of 02:13:15.

Interesting ?

Now more : both PRIM1 and SEC1 messages appear right after the "possible loss of signal" window.

Interesting ?

[glad rag]

Well here's hoping they find the recorders and they have viable data.

[Svarin]

mm43 wrote :

The only thing we positively know at this time is at the nominal 0210z AOC report, the aircraft was west of the track. This probably occurred within 30 seconds of the report and not as a premeditated crew action.1 - yes, AOC position at 02:10:34 (minus 5 seconds sending) was 3 NM west of track. AOC have higher priority than maintenance messages, their sending is likely to be close to real time.

2 - how do you know it was not through deliberate crew action ? For my part, I take it as another hint that they were awake and circumnavigating CBs, not as an upset that would have kicked them 3 miles offtrack.

[jcjeant]

Hi,

To wait until the arrival of the research boat on the site .. you can read this ... communication does not automatically mean information

PDF 3.5MB
Multiupload.com - upload your files to multiple file hosting sites! (http://www.multiupload.com/9I7JD5SI5X)

[bearfoil]

Machaca


"The other is: 1. Initial UAS leading to upset, leading to loss of AP
2. Manual recovery
3. FD bars re-appear
4. Catastrophic LOC due to following FD orders"Why have you assumed upset caused by UAS?? "First" Upset may have been generated by #4 ?? I think your short sequence is probably bankable. If 447 was occupied soldiering on 3:15 past LKP whilst dealing with UAS, they would have been 20nm past LKP and after things went pear, did they attempt a turn back to Brazil? Or, ......

Now 3:15 of continued flight would mean the "Fasten Seat Belt" was on and alerted, so perhaps another look at the conclusion that recovered victims were necessarily unbelted may be needed...

[rotor12]

The Ile de Sein will be on site this night

[henra]

The AD suggests that the initially commanded movement of the elevator could be too abrupt when the real speed of the airplane is much greater than what the AP 'thinks' it is.

Hmmm, my line of thinking went more in the direction that the actual speed was lower than what the sensors showed.
This would mean that following re-engagement of AP at a lower altitude 'Otto' would try to pull up at best climb (or max climb?) for the determined airspeed.
If the real speed is lower than what Otto thinks that's a perfect receipe for disaster. Trim Nose up, to high of a pitch angle and the engines below CG pushing hard causing further pitch up. Having no visual reference makes it hard to determine timely that something is going South.

The really intriguing question is: Why would the two gentlemen in row 0a/b be confident enough to re-connect the AP immediately after a significant upset.
On the other hand in the AD it was mentioned that exactly this happened in two prior cases. And the FPV being back maybe further increasing the confidence in everything being fine again.
Maybe even knowing they were in degraded law in heavy IFR they thought the AP might be the safer choice.

Just speculation though although a picture is starting to form...

[bearfoil]

henra

"Too abruptly" is not necessary for upset, imo. It may simply be a "routine" recapture of a/s and alt? Stall and LOC could follow either way. The AD would be more dramatic if such an occurrence (too abruptly) were possible, no?? Now this is semantics, but if immediate LOC were possible, wouldn't this a/c be under a bit more official sanction??

I do not believe the pilots wanted back in Auto immediately after losing the a/p. If their control had resulted in recapture of Bars and Bird, wouldn't they monitor for a bit ?

just sayin'

(edit) I don't know bout anyone else, but one word that gives me the willies is INTERMITTENT.

[ACLS65]

GerardC (http://www.pprune.org/members/285984-gerardc):
HF data transmission works fine for RA (or pleasure boats email traffic).
At the moment (and in the near future), it is not used (or planned to be used) for commercial aviation. Actually HACARS or HFDL (High Frequency Data Link) predates SATCOM ACARS and is still in use by a significant number of commercial airliners. I see a lot of traffic from HA, CO, AC, NW, NCA. UP, US, GTI, LH, ZS, AV, etc on everything from A319 to B777. One I don't see is AF, at least from my location.

My guess would be as SATCOM came out some carriers, manufacturers, etc may have moved to it and removed the HF capability, some may have both, and possibly some just have VHF and HF ACARS.

These initial ACARS systems have been extended to offer worldwide coverage, even in mid-ocean and
sparsely inhabited areas, using the Inmarsat facilities and HF data link, and to cover not only company
communications but also ATC services, starting with predeparture and oceanic clearances.
On aircraft delivered since 1998, the ACARS unit has been replaced by the Air Traffic Services Unit
(ATSU), which is designed to also accommodate safety-related ATC functions using the Aeronautical
Telecommunications Network (ATN), offering the majority of ATC and other communication services now
using voice, and more importantly, offering profitable migration to the ATN. The ATSU is the first unit to
host software from a number of different vendors. The same ATSU is also used on the A320 family of aircraft.
The ATN upgrade is being implemented to be available when the corresponding communication and
ATC services are in service.
From: New Avionics Systems —Airbus A330/A340

http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_30.pdf

[DingerX]

Okay, I went back and read it over again, and yes, you're right that the message in question is stamped to the minute 0213.

Here's what I understand (repeating what's been said before):

Cockpit Effect messages go out as soon as they are received.
A fault message opens a correlation window of one minute. At the end of the minute, those messages are prioritized and transmitted.

Of the 25 ACARS transmissions:

there are a slew of 17 messages, fifteen stamped 0210 and two stamped 0211 that are transmitted practically without interruption (with holes for two others), these were received from 0210:10 to 0212:16

Thirty-five seconds later (2:12:51), there's another sequence of three messages: one cockpit effect (stamped 0212) and two more faults (stamped 0211), ending with the one received at 2:13:14.
The gap observed between the message sent at 2 h 13 min 14 s and the one sent at 2 h 13 min 45 s is due, at least in part, to a temporary interruption in the communication link between the aircraft and the satellite
Transmission number 24 is sent at 2:14:20, refers to an intermitten FMGEC fault as reported by the AFS, and on this hypothesis, would be due to re-engaging the autopilot and causing a violent pitching.

So, on this hypothesis, the aircraft was flying smoothly. After the last cockpit alarm at around 2:12:40 (the NAV ADR disagree), things returned to normal. While the messages are going out to the satellite, at around 2:13:15, or at most forty seconds after the last NAV ADR disagree warning (or, if I'm wrong about how the ACARS WRNs are queued, all of seventy-five seconds), the crew punches in the autopilot and brings about the upset.

--
So it boils down to Svarin's question about that AFS message: does it imply that the A/P was on?
AFS may be 'Airbusese' for Autopilot, but generally differences in names imply differences in functions. Could a fault in the FMGEC relate to something like its envelope or airspeed functions? Does having the A/P off and being in Alternate Law 2 shut down the FMGEC?
The awkward wording of the BEA is to say, if there were a "Cockpit effect", it would have been a disconnection of the autopilot. From this I don't think we should be inferring that the A/P was on. It _could_ have been, and it _could_ have happened that way, but the questions on the interpretation suggest that there may not be any data to support it.

Whatever the "right answer" is, there will be data that has no relevance. But I'm not sure we can claim that there were no thunderstorms.

[Svarin]

henra wrote :

The really intriguing question is: Why would the two gentlemen in row 0a/b be confident enough to re-connect the AP immediately after a significant upset.Why ? Maybe because there was no first upset... Just an unpleasant but otherwise normally manageable UAS... When it is over, back to normal ops, get A/P back on. No need to tell the cabin crew.

[Fronl1ne]

Hi all,

Only SLF here, but one with reason to be flying to Brazil 3 times per year, and so have been watching your ruminations with great interest.

Just a quick question and then I will return back to the cheap seats.

Why can't the Pitot Tubes have a second, back up set recessed into the body of the aircraft and kept warm as toast and free of crystals, if/until required and deployed much in the same way the RAT is?

For a multi-million dollar aircraft moving 200 odd people about the planet, would that really represent a financial cost too far for manufacturer and customer alike?


It's been bothering me for a while that one.


Thank you for your time. Now slipping back into the undergrowth.

[Chris Scott]

Hello HN39,

Quote:
“I've been trying to imagine the mechanism by which re-engagement of the autopilot at corrupted airspeed would cause a violent upset. The AP controls altitude, so the first assumption one needs to made is that the altitude at re-engagement differs from the s elected altitude. Let's assume it is lower. The AP will then command movement of the elevator control to initiate climb to capture the selected altitude. The AD suggests that the initially commanded movement of the elevator could be too abrupt when the real speed of the airplane is much greater than what the AP 'thinks' it is. [...]”

I was considering a similar idea, though not necessarily with the extra control authority associated with under-reading ASI that you suggest. The possibility of a high FD pitch-bar, and the AP following same, may be subject to two points:
(1) pilots are warned not to engage the AP unless and until the FD command bars are very close to neutral;
(2) (tentatively) does the FMGC not default from ALT (hold) mode to the basic HDG/VS mode (or TRK/FPA mode, if appropriate) in the event that the aircraft deviates a certain amount from the selected altitude? (Currently have no manuals to hand, and a 30Kb/s internet connection, so cannot research this.)

In the event of (2) coming into operation, it could even have resulted from a relatively small excursion below the selected altitude. As the PF adjusted the VS selector-knob to a positive value, ALT* mode would take over sooner or later, possibly causing a pitch-up initially. Many of us have reason to remember the great authority of ALT* mode (altitude-capture mode) on the A330 and other Airbuses, and the potential problems associated with that in the past. No doubt Airbus addressed this issue in the 1990s. However, if the speed was already at or near the low-speed buffet, for whatever reason, any pitch-up would be... unfortunate. I appreciate, of course, that like me you may be pursuing a scenario in which under-reading of IAS leads the speed to be higher than normal. (Did the intakes freeze before the drain holes, etcetera...)

[Aileron Drag]

Fronl1ne,

The RAT can be deployed automatically if hydraulic pressure fails. That is achieved by the total 'system' sensing a total loss of hydraulic pressure or a loss of all engine power.

In the case of iced-up pitots, the system would not 'know' that ice was causing erroneous readings. That is to say, the aircraft systems would need to be 'told' that the sensed 'q' was not to be trusted, because of ice.

But how could you tell if ice was causing the data to be unreliable? The systems would simply take the 'q' reading as correct, even if it was not.

It's difficult to imagine, therefore, how an automatically deployed standby pitot system would operate.

Maybe the engineers on this thread could expand on this.

[wes_wall]

Bearfoil

so perhaps another look at the conclusion that recovered victims were necessarily unbelted may be needed

This has been a question I have had since this thread began. The crew had to be aware of what lie ahead of them, visual or electronically, and at that time in flight, historical experience of flying this area, common proceedure would dictate seat belts be on. Yet, from what precious little evidence we have, the question remains unanswered, on or off. Information regarding crew station(s) that we have seen can make a valid argument that they were not on, and that the cabin staff may have been up and about when the event occured. Body recovery however does not necessarily mean that these individuals were not belted in at impact. Paxs leave seats on impact even when belted so I do not believe a defendable conclusion can be drawn from this. Further, reportedly paxs are observed still in their seat at the accident site.

[Mr Optimistic]

WW, so what do you think about post #38 ?

[henra]

henra wrote :

Why ? Maybe because there was no first upset... Just an unpleasant but otherwise normally manageable UAS... When it is over, back to normal ops, get A/P back on. No need to tell the cabin crew.

If it weren't for the location where the wreckage supposedly was found and the time of the Cabin Vertical Speed advisory in relation to this ACARS message I would absoultely agree with your scenario. Has some merit to it.
However, they would have travelled a siginificant distance in these 3 minutes until 2:13:XX namely between 20 and 25nm. After that they would have to shed 35000ft in a short time and return to where they came from and arrive there at little forward speed. Would be difficult to align with the 2:15:15 as likely latest crash time and the time of the cabin VS message marking probably the passing through 8000ft. This message is transferred directly subsequent to the AFS warning.
Still a possible scenario though..

Looking at the timing of the ACARS Messages again I'm not really sure any more if we are on the right track!?
The failed FPV activation is stamped 211, NAV ADR Disagree is stamped 212 which could imply that at 212 things were not back to normal.
That would not leave much time to re-connect the AP and to lose it completely.
However I have to agree either this sequence could indicate a seemingly 'benign' environment where they simply try to get it back to normal ASAP after a seemingly non-dramatic event or it could be a sign of desperation or we are reading something into this message which is simply not there.

The last point makes me curious if no one on this planet can really elaborate/explain what could cause these ACARS messages / what is the logic behind / what they exactly mean or those who know keep it as a secret :confused:

[Pugachev Cobra]

It just occurred to me, have anyone in all the AF447 threads considered the possibility that the last ACARS position report was not at FL350? I read the ACARS sequence and it just contains lat/lon coordinates, no altitude information (nor track, heading, speed, etc.)

The aircraft could be well below that altitude, and AFAIK, at the LKP report, they could be in another heading, is that correct?

Now, maybe my math (and distances information) is wrong here, but from the crew position report at INTOL and their estimates to SALPU and ORARO, the groundspeed varies considerably to the LKP.

But, considering their last estimate 02:00 UTC at ORARO and the LKP at 02:10:34 UTC, their groundspeed was ~273 knots. Does that compute?

INTOL - SALPU (122nm - 13.25 mins elapsed): ~552 kts

SALPU - ORARO (122nm - 12 mins elapsed): ~610 kts

ORARO - LKP (~48.18nm - 10.57 mins elapsed): ~273.6 kts

Isn't it possible that at the position report the aircraft was turning back to Brazil or something different than flying the planned route, at a different altitude and speed?

About Svarin's observation, maybe something got lost from the french to english translation. Anyone here good in french?

The original french report explanation about the AFS occurrence:

Ce message ne peut pas être la trace d’un reset, ce qui exclut notamment la possibilité d’un arrêt manuel. Ce message pourrait être la conséquence d’une incohérence entre les deux chaînes internes du FMGEC (COM et MON). Une telle incohérence pourrait elle-même être la conséquence de valeurs erratiques des paramètres d’entrée. Quoi qu’il en soit, les seules conséquences d’un tel message ne peuvent être que le désengagement d’automatismes dont les messages cockpit effect associés ont déjà été émis à 2 h 10.
Le caractère « INTERMITTENT » signifie que l’anomalie a duré moins de 2,5 secondes.

I think Svarin made a point that the crew was alive, alert and well in the flight deck, by trying to reengage the autopilot.

However, for an automatic commanded pitch down (or up maybe), we have seen that the A330 doesn't need a connected Autopilot to command a abrupt pitchdown - read QF72 accident investigation..

[jcjeant]

Hi,

One from neighbors

Google Vertaling (http://translate.google.be/translate?u=http%3A%2F%2Fhenrimarnetcornus.20minutes-blogs.fr%2Farchive%2F2011%2F04%2F20%2Fle-decrochage-d-airbus.html&sl=fr&tl=en&hl=&ie=UTF-8)

Original page:
Le « décrochage » d (http://henrimarnetcornus.20minutes-blogs.fr/archive/2011/04/20/le-decrochage-d-airbus.html)

[DingerX]

A. I think we're probably reading more into it than there is. We are humans, and we've evolved to see more patterns than exist in reality (better to see a non-existent bear and live than not to see one that is there).
B. The logic for ACARS messages is published, we're just trying to use them for something they were never intended to do. They're there to report aircraft position, status and issues that may require maintenance. They're not there to record flight data.
C. There's no secret, but I wonder how much experience there is with A330s reporting exactly this set of ACARS messages. Again, we're only getting a few indications here.

You can't really rule stuff out here. For example, we can't say "they didn't fly into a huge cell, because if they did, they would have seated the FAs and everything would have been secured." We can't say that, because our weather data suggests exactly that, and if they had seen what our weather data shows, they would have gone more than a little bit off-track to avoid it, as the other aircraft did.
If the evidence shows that they weren't belted in, all that tells us is that the flight crew were not expecting turbulence, which is a state consistent with flying through a huge cell (that is, not being aware of it; another state consistent with flying through a huge cell would be being aware of it, but underestimating its intensity).
In any case, what about the other flights that were threading the thunderheads in the ITCZ that evening? Did they secure the cabin?
We can't argue that 39 flights in an A332 implies familiarity with the wx radar if there's formal training or evaluation on using it.

[DingerX]

e message ne peut pas être la trace d’un reset, ce qui exclut notamment la possibilité d’un arrêt manuel. Ce message pourrait être la conséquence d’une incohérence entre les deux chaînes internes du FMGEC (COM et MON). Une telle incohérence pourrait elle-même être la conséquence de valeurs erratiques des paramètres d’entrée. Quoi qu’il en soit, les seules conséquences d’un tel message ne peuvent être que le désengagement d’automatismes dont les messages cockpit effect associés ont déjà été émis à 2 h 10.
Le caractère « INTERMITTENT » signifie que l’anomalie a duré moins de 2,5 secondes.

Translation: This message cannot be due to a reset, which excludes in particular the possibility that it was manually shut off. This message could be due to a disagreement between the two internal channels of the FMGEC (COM AND MON). Such a disagree could, in turn, be the consequence of erratic input values.
Whatever the case may be, the only possible consequences of such a message can only be the disengagement of automation whose associated cockpit effect messages were already transmitted at 0210.
"Intermittent" means that the anomaly lasted less than 2.5 seconds.

Well, to be precise, the message doesn't have consequences, rather whatever sent the message would have also instructed the A/P to disengage if it were engaged. That's "only possible": they are not making any statement on the A/P status.
They are also implying that if the flight crew "reset" the FMGEC by turning it off and on again, there would be a different set of messages (otherwise, I cannot see how they can claim that it "excludes the possibility" -- it only excludes the possibility that this message was generated by a reset, not that a reset occurred previously or after).

I will now join -gums- in shutting up (but not in his insight, alas).

[mm43]

Pugachev Cobra;

The ORARO estimate of 0200 is wrong, and it should have been 0204. It was possibly misheard due to accent/static.

The 02:10:34 AOC report will have left the a/c at 02:10:30. When it was generated is not known, but AOC reports have precedence over other ACARS messages and the BEA have stated its nominal time as 0210.

The preceding positions are listed below, and you will note that GS was fairly constant at around 467KTS.

ACARS AOC Positions
0210: 02°58'47"N 30°35'23"W
0200: 01°48'00"N 31°08'59"W
0150: 00°38'23"N 31°45'36"W
0140: 00°29'23"S 32°22'11"W
0130: 01°38'59"S 32°58'47"W
0120: 02°49'11"S 33°36'35"W
0110: 04°01'11"S 34°14'24"W
0100: 05°12'35"S 34°52'11"W

The altitude at 0210 when the flight law reverted to Alternate Law was FL350 at 272 +/- 2 KCAS as recorded by the Rudder Travel Limiter Unit (RTLU) which set the maximum rudder travel to +/-7.9° based on the last valid air data.

http://oi56.tinypic.com/ivvayo.jpg

EDIT :: As kindly pointed out by HazelNuts39 in post #114 below, there are other permutations that will provide the same CAS but with different levels and Mach numbers.

[ChristiaanJ]

About Svarin's observation, maybe something got lost from the french to english translation. Anyone here good in french?
The original french report explanation about the AFS occurrence: [etc.]
It's not my mother tongue, but I've lived and worked here in France long enough (35 years in aviation, automatic flight controls, etc.) to be able to do a translation.
To me the translation DingerX quotes is sufficiently accurate to all normal extent and purposes. If there is anything you query in particular, just ask.

Well, to be precise, the message doesn't have consequences....Quite.
But the French in the report is fairly convoluted (in the best French formal report-writing style), and it's easy to read too much into it.

[Shadoko]

Hi,

Just one remark about the "galley catering-cannister stowage unit" picture that I posted (#3787). This picture have been posted on a now apparently dead French forum (Eurocockpit). It was said there the latches positions were not conclusive. And perhaps, the box on the top (which position was very astonishing for me if there was a high sea) had been put there when its recovery happened.

And one question: I think I have understood (imho!) that in "normal" flight with AP engaged, moving the thrust levers or the stick (right words?) do get the autopilot off. And then, you have to manually re-engage it to get it again. But what happen if nobody move either of them after automatic disengagement? Is the AP going back automaticly if the a/c "think" the speed indications are right back?

Sorry, if this has been answered before (and thanks to all this brainstorming by knowledgeable people).

[mm43]

ChristiaanJ;
But the French in the report is fairly convoluted (in the best French formal report-writing style), and it's easy to read too much into it.An interesting point. With your knowledge of French "aviation speak", do you think that the BEA's English translation of their preliminary reports is generally "on the button" in relation to English "aviation speak"?

[HazelNuts39]

mm43;

From the BEA text on the RTLU: As an example, at FL350, this travel is obtained for Mach 0.8 +/- 0.004, corresponding to a CAS of 272 +/- 2 kt.As another example, at FL362, Mach 0.82, 272 kCAS?

[mm43]

HN39;

Thanks for reminding me! Very true.
I have previously posted the same comment.:eek:

[ACLS65]

I was looking at some of the other incidents mentioned in the second interim AF447 report when I noticed this in the TAM report.

http://dms.ntsb.gov/aviation/AccidentReports/lqkiul2aggxtq255gde13ufg/B04252011120000.pdf

"This incident report has been combined with NTSB Incident Report DCA09IA064.
Updated on Mar 29 2011 6:09PM"


But the Northwest report (DCA09IA064) looks unchanged...

http://dms.ntsb.gov/aviation/AccidentReports/iv5mqk22p1fdt4fhvsrgkv45/D04252011120000.pdf

Anyone know what is up?

[SonarKing]

Considering the velocities typically involved in air accidents over water, wave height has little to do with airframe conditions through impact. After the preliminary survey of the fuselage the investigators have data that shows almost no horizontal component pre- sea surface contact.

[Mr Optimistic]

From post #79

'This means the a/c likely did not crash right after end of ACARS sequence. '

Could someone explain this please ???

[ChristiaanJ]

ChristiaanJ;
An interesting point. With your knowledge of French "aviation speak", do you think that the BEA's English translation of their preliminary reports is generally "on the button" in relation to English "aviation speak"?mm43, rather than 'wading back' through the topic, could you give me a link to the latest BAE report, and I'll go back to the site, look at the English and give you my assessment (for what it's worth).
From what I remember, it's definitely better than Google Translate (which BTW has remarkably improved over the last year or so, and is usually adequate for a first look, especially if you have some knowledge of the source language), but not always done by English-mother-tongue translators.

[ACLS65]

Link to reports:

FLIGHT AF 447 (http://www.bea.aero/en/enquetes/flight.af.447/flight.af.447.php)

[JD-EE]

RR - I guess I'll kick in another comment (aside from being double qualified for QCWA). The aircraft pilots are pilots first and radio operators second. With SelCall I am not sure they listen to the radio enough to get "The Ear" that helps drag stuff out of noise.

On the other paw, ACARS is digital. It would have a pretty good chance of getting through mere static. And I note, everybody who seems to be wx aware of that particular evening and location suggests there was little or no lightning involved in the storm system. So "What QRN?"

[ACLS65]

Everyone has been looking at them long enough, but here is what they sound like.

http://www.astrosurf.com/luxorion/Radio/mode-acars.wav

http://members.optusnet.com.au/extremescan/sounds/acars.mp3

[JD-EE]

Graybeard,

There is a "feature" of HF that renders your comment pretty much meaningless, at least for reception.

The aircraft would be operating well below 10MHz and probably around 5MHz or even 3MHz at that hour of the night in June of 2008. Above those frequencies the propagation would simply not be there. At those frequencies you can use a receive antenna that is only 10% efficient or even less and still receive as well as a "good" antenna would receive. Ambient noise that cannot be escaped makes up the difference. At 3MHz it's on the rough order of 20dB above "Boltzman" or theoretical minimum noise levels. (When on those bands I always intentionally put in 10dB to 20dB of attenuator following the antenna. It makes the receiver's so called "intermodulation distortion" (birdy level) lower.) This noise is an issue until you get up around 100MHz give or take a little.

The aircraft would HEAR DAKAR just fine. And unless DAKAR had storm static to worry about they'd be able to hear the plane as well as they ever hear the plane.

[henra]

@Pugachev_Cobra:

Thanks for posting the original French text. Should have looked it up myself earlier. From what is left of my French I see that it is a bit different from what I read into the English description.
The French text does not point to a re-activation of the AP. It is merely stating that if the AP was connected before, it would have been disconnected as a consequence of this message.

So I take it, I read to much into this message.

Conclusion for me: Attempted/temporary re-activation of AP still possible but no direct hint towards it, at least not from this message (I hope they got at least the French text right...)

[DozyWannabe]

And one question: I think I have understood (imho!) that in "normal" flight with AP engaged, moving the thrust levers or the stick (right words?) do get the autopilot off.

Nope - sufficient pressure on the sidestick *will* disconnect the AP/FMC, in much the same manner as it does on airliners equipped with yokes. However, thrust lever position is used to control the mode that A/THR is engaged in, so disconnecting A/THR by moving the levers would be counter-intuitive. A/THR disconnect is achieved by pressing the red buttons on the side of the thrust lever handle. Holding those buttons for 15 seconds disconnects A/THR completely and disables it permanently until ground system restart.

Is the AP going back automaticly if the a/c "think" the speed indications are right back?

Can't say for sure, but I very much doubt it. The myths about what AI's FBW implementation will and will not do tend to muddy the waters though. The computers will do exactly as the pilot asks of them and will not intervene unless the pilot is trying to do something dangerous (pull into a spiral dive, pull up without increasing thrust etc.).

[ChristiaanJ]

ACLS65, thanks for the link.

Just having been reading through most of the English version of the 1st June 2009 report.
Some of it is clearly translated French, but none looks bad enough to lead to obvious misinterpretation by people familiar with the subject.

mm43 (re your earlier post), I would call it acceptable, but since I know French I can see where some of the terminology would have come from, even without having the French original next to the translation....
Whether it's as understandable to somebody without any French... I can't really judge.

HN39, classic problem.... (I should know... been there, done that. Plus a professional technical translator as a wife.)
I agree the 1st June 2009 report translation could have been better.
Not sure whether the BEA thought it useful to have somebody 'nitpick' the text. It was aimed at professionals, not curious amateurs.
It's why I always try to read the originals, rather than the translations.....

[Chris Scott]

HN39 and others,

I made the mistake, on April22 (Good Friday), of suggestinghere (http://www.pprune.org/tech-log/395105-af-447-search-resume-189.html#post6405872) that the stall warning provided in Alternate Law is IAS-based. It is, as HN39 quickly pointed out, AoA based. (While I was out of circulation, that Part-1 thread was closed and locked, so am unable to edit the error.)

The fact that the stall warning is indeed AoA-based, as one would like, makes it all the more puzzling that as many of 9 of the 13 cases of unreliable airspeed indications leading to Alternate Law − analysed by the BEA in their Interim 2, 1.16.3 (the 13 best-recorded of the 36 incidents summarised in Appendix 7 of the same report) − involved stall warnings. Why puzzling? Because the same analysis seems to support the theory that these pitot problems lead to under-reading, not over-reading, airspeed indications. If the A/THR (not to mention the crew) is being led to believe that the IAS is falling when it isn’t, why in level flight would these 9 cases involve the aeroplane finding itself at a high-enough AoA to trigger a stall warning?


Extracts from the BEA report, referred to by HN39:

“The speed anomalies can be characterised by two distinct signatures:

- intermittent falls (peaks);
- fall followed by levelling off (continuous period).
[...] the lower speed limits recorded were below 100 knots.
[...]

“In the cases studied, it is notable that:
- the airplane remained within its flight envelope...”

Although the ambiguous expression “peaks” (has something been lost in the translation?) might be interpreted as indicating an intermittent rise in indicated speed in some cases, I don’t think that is intended. The burden of the analysis seems to be of consistent under-reading of IAS. On the face of it, this and a high AoA in level flight seem to be mutually exclusive, but the BEA does not address that apparent inconsistency.

However, turbulence with a gross increase in normal acceleration (load factor) is one possible explanation.

Quote:
“Turbulence was always recorded and reported. The levels felt by the crew varied from slight to strong. The recorded amplitude in recorded normal [acceleration] went from 0.75g/1.2g to 0.2g/1.9g.”

Perhaps HN39 might be able to provide a graph of level-flight AoA versus load-factor, please?

Other inconsistencies of analysis results are apparent in the BEA report − always presented without comment. In this case of unreliable airspeed indications, the most striking vulnerability in the stall protection logic − if the BEA is telling us the whole story − is, as quoted by HN39:

“In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold. In clean configuration, this threshold depends, in particular, on the Mach value in such a way that it decreases when the Mach increases. It is the highest of the valid Mach values that is used to determine the threshold. If none of the three Mach values is valid, a Mach value close to zero is used. For example, it is of the order of 10° at Mach 0.3 and of 4° at Mach 0.8.”

Given that an IAS of 100 kts − one of the figures recorded in the analysis − at FL350 is in the region of Mach 0.3, the inference is that a stall warning would not happen until an AoA of 10 degrees. On the other hand, in all cases studied, “the airplane remained within its flight envelope...”

As HN39 puts it:
“the occurence of stall warning in the cases studied by BEA does not seem to match the higher threshold after loss of IAS.”

[Fronl1ne]

Hi Aileron Drag,

Thanks for the reply.



The RAT can be deployed automatically if hydraulic pressure fails. That is achieved by the total 'system' sensing a total loss of hydraulic pressure or a loss of all engine power.

In the case of iced-up pitots, the system would not 'know' that ice was causing erroneous readings. That is to say, the aircraft systems would need to be 'told' that the sensed 'q' was not to be trusted, because of ice.

But how could you tell if ice was causing the data to be unreliable? The systems would simply take the 'q' reading as correct, even if it was not.

It's difficult to imagine, therefore, how an automatically deployed standby pitot system would operate.

Could it not be designed to deploy when all 3 pitot tubes disagree simultaneously, or on the command of a pilot who has an intuition that something isn't right? Is the pitot tube system prohibitively expensive?


Again, thank you for indulging my query.

[mm43]

ChristiaanJ;

Thanks for your thoughts on the BEA's French to English translations. I have both forms of the reports on my computer, but being naturally lazy, I tend to accept the English version, and only if there is some doubt do I refer to the French original. As you pointed out the Google translation has improved immensely over the last year or so, and I can also use my rusty French to sort mixed tenses.

[CONF iture]

So if from ACARS the a/p dropped by command from (Computer) ADIRU disagree, then I can't imagine why auto would be allowed to re enter the room even if invited.

Initially flight controls revert to ALTN law due to significant differences between all airspeed sources, AP and A/THR are lost, but if later on 2 airspeed sources become similar while still erroneous, FD bars will reappear and AP and A/THR can be re-engaged. However, ALTN law is latched due to the initial ADR disagreement.


Wouldn't the AP adjust its command before it results in an uncontrollable attitude?
Although some protections are still available, PITCH ATTITUDE is not one of them ...
I also think that if flight controls move with the amplitude adapted to low speed but the real airspeed is nowhere close to that, it can be very messy as henra put it.


You are right, we ALL take whatever weather deviation is needed, AND (preferably before deviating...) we send a message (HF or CPDLC) : "request deviation up to XX Nm due to weather".
Do not forget these routes are not as crowded as the NAT OTS area : after dozens of SA crossings (before and after AF 447 crash), I can't remember of much (if any) "deviation" chat on 123,45 (or 121,5).

On a 330 in the NAT OTS, weather deviations are pretty rare I must say. How commun is it over the SA ?


Is the AP going back automaticly if the a/c "think" the speed indications are right back?

Whatever the circumstances, the only option to engage one of the APs is to manually select it. In this scenario, you would have to re-select it as well.

[lomapaseo]

Fron

Could it not be designed to deploy when all 3 pitot tubes disagree simultaneously, or on the command of a pilot who has an intuition that something isn't right? Is the pitot tube system prohibitively expensive?



Expense is not a decision gate here.

Measured reliability is the issue. The more systems you add the less reliable you are (less safe).

The typical design decision here is to have a backup that gives up on trusting screwy readings and still flies the aircraft. Else one would have to roll some dice to pick which reading is correct. I don't for an instant trust yet another probe with way less than 100% relibility (it only gets used once in a lifetime) that is expected to solve a unique problem.

[Gerard13]

henra

"The French text does not point to a re-activation of the AP. It is merely stating that if the AP was connected before, it would have been disconnected as a consequence of this message."

With all due respect, not quite correct. The French text is simply stating that this message cannot be a consequence of a reset. Nothing more.

I'm French, so hopefully can still correctly interpret such sentences... And yes, French can be convoluted and confusing, sometimes on purpose!

[CONF iture]

“the occurence of stall warning in the cases studied by BEA does not seem to match the higher threshold after loss of IAS.”

Chris and HN39,

I think I understand how you see this, and I would like to risk an explanation.
The following quote from the BEA :
If none of the three Mach values is valid, a Mach value close to zero is used. For example, it is of the order of 10° at Mach 0.3 and of 4° at Mach 0.8
should, imo, be considered as follow :
If none of the three Mach values is valid, a Mach value close to zero is used. For example, it would be of the order of 10° if the Mach was really at 0.3 and of 4° if the Mach was really at 0.8

A Mach 0.3 value can not be taken into account since none of the 3 Mach values is considered valid.
Do I make sense here ... ?


... so disconnecting A/THR by moving the levers would be counter-intuitive. A/THR disconnect is achieved by pressing the red buttons on the side of the thrust lever handle.
Moving the thrust levers before pushing one of the red buttons is usually a vital part of the standard A/THR disconnection procedure !
The other standard A/THR disconnection procedure is to simply set all thrust levers to IDLE detent.
But to answer Shadoko question, moving the thrust levers cannot disconnect the AP.

The computers will do exactly as the pilot asks of them and will not intervene unless the pilot is trying to do something dangerous
QF72 proves you wrong.
It won't make you an Airbus hater to admit it once for all.

[RR_NDB]

I mentioned the current VERY POOR ANTENNAS because they are also parallel to the vertical fin what further degrades the performance.

Edited:

The shunting feed of VS is a good solution.

It´s not "an antenna parallel to VS" as i thought.

It´s a way to feed RF to the VS metal structure.

It has some disadvantages but works.

The efficiency could be good with a low SWR and a good ATU.

About effectiveness i reiterate the wire antennas used in old birds presented much higher ERP.

But the jet age (a/c speed) and space age (SAT) reduced the relative importance of HF to a/c comm.

____________________________________________________________ ___
Initial post

With the advances in other options HF had a decrease in it`s use.

The old wire antennas were much more effective. But with the jet age they were no longer used.

The "integrated" antennas are low efficiency radiators compared to the ones used in L188, C130`s and the older planes.

Electrically speaking the basis is the low radiation resistance and it`s lenght and position in the a/c.

If the commercial planes were equipped with good HF antennas the comm would be completely different.

After a trip with DEP 2 hours from now i will post a better reply with the laptop.

Well, let´s continue:

A short antenna has several disadvantages compared to one that is in the order of the magnitude of the wave lenght you are using.

At night in June in the middle of the night you may be required to use a low HF frequency.

When i worked doing HF equipt. maintenance in the rigs from PAA (12ACX, 4WTFA, etc) i remember the QRG 2910 KHz. An adequate lenght would be in the range of 60 ft. The Connies, etc used good antennas (long). With an old Collins ART-13 with derated tube to 100 W you had a very strong signal in AM.

Later with the introduction of SSB (USB, for aviation) it was possible to reduce the size paying some penalties in performance. Anyway the 707 fin and the LH wing antennas used by Lufthansa delivered good signals.

More and more the SIMPLE SYSTEM (using just "free" ionosphere layers) was replaced by repeaters, etc.

For example, this repeaters PLAYED A ROLE in MAC between N600XL and PR-GTD in Brazil.

I mentioned the current VERY POOR ANTENNAS because they are also parallel to the vertical fin what further degrades the performance.

It works but when you have 40+ years of HF experience in thousands of mobile operation (Land mobile, maritime mobile and air mobile) you has the obligation to say the HF antennas equipping the new planes (let´s say, after 707) ARE POOR.

Finally we must mention some EMI/EMC issues, a challenge for new composite "intensive" a/c.

I could assure that with 200W rms out, SSB and a "normal size antenna" your performance (comm and data) would amaze the younger crew.

Other considerations like S/N (signal to noise ratio), ionospheric propagation, etc i could comment further but this is not the issue here in the AF447 case.:zzz:

[mm43]

JD-EE;
The aircraft would be operating well below 10MHz and probably around 5MHz or even 3MHz at that hour of the night in June of 2008. Just as a refresher, I've thrown some facts together based on what was actually happening at the time - NOTE : June 2009!

01:31:44 - RECIFE (126.5MHz) gave AF447 the ATLANTICO HF frequencies: 6649 or 5565kHz, then 6535kHz after the TASIL.
01:33:25 - AF447 contacted ATLANTICO on 6649kHz.
01:35:15 - AF447 reported to ATLANTICO that they passed INTOL 0133, at FL350, estimating SALPU 0148 and ORARO 0200. SELCAL - CPHQ.

HF Propogation
At 0200 UTC 2009-06-01 LKP to NATAL (Atlantico/Recife HF)
MUF = 7.0MHz, LUF = 2.0MHz, Solar Flux = 71, Hops = 1, Dist = 592NM.
Primary 6649kHz, Secondary 5535kHz

At 0200 UTC 2009-06-01 LKP to DAKAR (Dakar Oceanic)
MUF = 12.5MHz, LUF = 2.0MHz, Solar Flux = 71, Hops = 1, Dist = 1053NM
Primary 6535kHz, Secondary 5535kHz

Air to Air
The EUR - SAM Pilot to Pilot frequency is 123.45MHz.

http://oi32.tinypic.com/wtdjwo.jpg

The graphic shows the position of all four Air France flights at around 0210, and confirms that AF447 was well within VHF range of the other 3 aircraft.

Summary
Solar conditions were quiet ~ low activity. No lightning was observed by satellite detection, or reported by other flights that night in the Atlantic ITCZ. St. Elmo's fire was reported by a flight, and AF459 did report difficulties on HF, but whether that was due to static or just no reply from the station they called, I do not know.

[DozyWannabe]

QF72 proves you wrong.
It won't make you an Airbus hater to admit it once for all.

*sigh*

OK, how about "The computers, when behaving as designed - which is around 99.9(rec)% of the time - will do exactly as the pilot asks of them and will not intervene unless the pilot is trying to do something dangerous".

It wouldn't do you any harm to admit that Asseline could have screwed up, Jacquet always was on a hiding to nothing and you'll never get your yoke back, either - but it isn't going to happen.

Keep playing the subject though. :)

[JD-EE]

RR_NDB

Inefficient and ineffective are two different ballgames.

As I pointed out inefficient does not matter at HF frequencies most used for aircraft unless the antenna is extraordinarily inefficient. The antenna matching elements are not that bad. (If they were they'd break down from the heat they generated.)

On transmit it matters a little. But, if communications works over the required ranges with required reliability, what matters the transmit inefficiency?

Now let's look at how inefficient the antenna may be. I believe the HF antenna is in the leading edge of the "plastic" vertical stabilizer. That makes it about 35' long or a quarter wave at about 7 MHz. So it will be quite efficient at 7 MHz or a frequency near that. (It may not run the full length of the VS leading edge.) The matching circuit would have less than 3 dB of loss even at 3 MHz. Matching might get "dicey" at frequencies near 14 MHz. But even that can be dealt with. End fed half wave antennas do remarkably well with a suitable matching circuit. Zeppelins used this form of antenna, hence that antenna's name, Zepp.

3dB loss is no big deal when power levels less than a watt are known to work over distances of 1000 miles at night on 75 meters unless the propagation goes REALLY sour, which it does during periods of solar minimum. That's why God made 160 meters, one might say. If dummy load leakage can make it from Idaho to Los Angeles quite legibly under quiet conditions that gives you an easy 1000 times more power for punching through the crud Ma Nature throws at you. Planes do not use 5 watt handi-talkie power levels. They run 100 W to very conservative 1 kW depending on the radio selected.

Now let's head bang on the antenna configuration. The trailing wire can be a really nice antenna with wonderful range, if you want to talk to somebody off to one side or the other of your plane. It's not "ideal" for talking directly ahead or to the rear. Drag is horrible, especially at Mach 0.8 type speeds.

The slightly newer style of a wire running from behind the cockpit to an attachment on the tail is required for tin cans. Since the active element is very close to the counterpoise the efficiency can suffer dramatically. And it has high drag. It also suffers from some of the same directivity problems. They'd not work all that well to the direct front or rear. Finally the close proximity to the ground plane makes the antenna pretty much of an NVIS device, Near Vertical Incidence Signaling - short range regional. It hurts the long distance capabilities.

Embedding it in the tail is rather nice as a configuration. It is near vertical with, as a result, a nearly circular low elevation angle radiation pattern. In other words it is a really good long distance antenna. It works well in all directions including the critical direct forward and rear directions. It suffers a little for lack of a nice ground plane unless some screening is included around the base of the antenna. I'd imagine they've worked out something. On the whole 50% efficient is probably good enough. (Demonstrably it is good enough for transmit. And for receive it's efficient enough the inefficiency could even be increased to minimize sensitivity issues in a very high noise level environment.)

So, the antenna is effective. And it costs less than the longer antennas. So arguably it is more cost effective than the alternatives and not nearly as bad as a 9' whip on the back of an automobile. Now THAT is what I call inefficient.

Now that I've slammed this one into the ground (Earth for you British if you want the intended pun) can we quit carping about the antennas? I don't want to threaten dragging out various handbooks and playing pedagogue WAY off topic to prove my points. (The RF I am sure about. The precise VS dimensions and antenna dimensions within the VS structure are rough based on what information I could find in a 3 minute search using Google. Tail height is 9.3 meters. It's swept back some so I gave it a few more feet for the length of the leading edge.)

[JD-EE]

mm43, thanks for the actual numbers. The MUF towards DAKAR surprises me for how high it is. I guess I'm too used to conditions around LAXish areas. I'd expect DAKAR to communicate with the plane nearer to 11MHz given the MUF cited. But 6-7 MHz would work OK. (And the antenna would be a little happier.)

[slats11]

I know this has been hinted at previously, but this discussion does make me think about the qualities required for pilots flying these aircraft While the pilots are trained in these computerized flight control systems and have a degree of familiarization with them, do they actually have a deep understanding of them? If not, then is desirable to be operating aircraft without a comprehensive understanding of these systems?

Previously we talked about "airmanship". And that quality is clearly vitally important (witness Sully's landing in the Hudson and even the last seconds of BA038). But do pilots today need more than this? Do they also need to be masters of current technology FBW and automated systems? And if so, is it possible to be that, and to be a good pilot also? Or is that skill set asking too much of one profession?

It appears inevitable that automation will increase. And if commercial air travel is safer than ev before, then perhaps we are on the right track overall (despite the occasional disaster such as this). Perhaps we have to be pragmatic and look at the big picture.

Careers evolve over time in the face of new technology, and I guess that is progress. But I wonder if flying a jet today is still the same job as before, or whether it is something new and fundamentally different. And whether pilot training today gives people the skills they will need.

Or do we need to go back to the days of a flight engineer? But this time, someone trained in computers and systems and instrumentation rather than engines.

I know you can argue that you can't over-react to a single incident. But QF072 could have ended very differently. And that Qantas 380 with that engine problem out of Singapore - true it started as a mechanical failure, but the crew was overwhelmed with the amount of information presented to them and you wonder how this would have turned out with a "normal" crew rather than a lot of experienced check pilots.

[RR_NDB]

Hi, JD-EE

I will start now and continue later editing my answer:

1) The HF antennas are not located in "no conductive VS". :=
2) They run near and in PARALLEL to metal. Much better would be at right angles (like the 707 Collins design)
2a) Correction: They RF excite the VS in a "shunt configuration". A driven thick wire is connected to VS at an height ranging from 3 to 9 ft or so. This is not the "main" antenna. But radiates (when transmitting) some of the energy because of high RF current circulation. Iy actually supply RF energy to VS. Can be considered part of the coupling circuitry (Z match).
3) The signal to the rear IS MUCH WEAKER simply because no "return=ground plane" behind VS.
4) Drag for a trailing short wire (let´s say 60 ft) i don´t think would be a problem. Ok, you have APU, etc. But i´m not advocating the use of the System Amelia Earhart had in the Electra or the reel wire in the C47, etc. What you say about trail a 30,000 ft like the 707/CFM56 of USN for subs? Ok, it oscillates and USN paid for a damper for it, :)

To be continued...:zzz:

Rgds, appreciated in commenting

[Graybeard]

Modern HF antennas and couplers in commercial aircraft are quite different from those described above. By modern, I mean 1968 and newer.

All the modern airliners use current-fed notch/slot antennas. They amount to a battery cable attached to the dorsal or tail fin; very low voltage, very high current. The whole plane becomes the antenna. Yes, if designed and maintained correctly, it is highly efficient.

The best commercial antenna flying still today was on the first DC-10, and continued on the MD-11. It was designed by Ben Hornby, an ex-pat Brit whose learning was on the VC-10 or something. The DAC tri-jet has the ideal location for the shunt fed antenna, just below the #2 engine, for really good coupling. The L-1011 was not so good, and Hornby had to help them make it work.

Boeing did not switch to the leading edge shunt antenna until pressured by airlines some years later. Their first was in the 727, which design they bought from Eastern Airlines. Boeing still did not understand shunt antennas a dozen years later, so the 767 had terrible HF for years, maybe still.

Airbus adopted shunt antennas in the fin from the beginning. I don't know how well they understand the dynamics, but feeding hundreds of amps into a carbon fiber fin makes me wary. That said, I have no direct experience with A/B HF antennae. AA587 and prior events it highlighted really had me wondering.

Airline HF is 400W P-P, BTW, and always USB, upper sideband. The antenna slot in most airliners is no more than a meter long.

Is this pertinent to AF447? Only regarding SelCal, I guess.

GB

[ChristiaanJ]

Most people will be unfamiliar with notch/slot type HF aerials, because they're generally invisible under the paint.

For some unknown reason the HF slot aerials on the Concorde prototype 002 were never painted over, so this photo at least gives an idea.

http://img.photobucket.com/albums/v324/ChristiaanJ/002tailandaerials.jpg

An amusing detail, which illustrates the amount of HF current in the surrounding structure...
During the first in-flight tests of the HF, Concorde "wagged its tail" whenever the HF was keyed.
After some detective work, it was found that the yaw rate gyros inside the tail picked up enough HF to disturb the yaw autostabilisation system and generate spurious rudder commands.... A few filters in the right spots solved that one.

[kit344]

Information, 26/04/2011 (http://www.bea.aero/en/enquetes/flight.af.447/info26april2011.php)

"The cable vessel Ile de Sein operated by Alcatel-Lucent and Louis Dreyfus Armateurs, which arrived in Dakar at 10h UTC on Friday 22 April, left the port at 18h20 UTC the same day, with 68 people on board, including the crew of the ship. It arrived in the accident zone this morning at 05h00 UTC.

During the crossing, a series of meetings took place to review the organisation and objectives of phase 5, the technical specifications of the Remora 6000 and the safety measures on board. Those present included the crew, the nine ROV operators and technicians from Phoenix International and the investigation teams.

Under the direction of the BEA Investigator-in-Charge, two working groups were formed in order to:

- continue the analysis and interpretation of photos taken by the Remus during the previous phase, in particular of the aft elements of the wreckage so as to be able to localize the flight recorders,

- study the operational procedures aimed at recovering the airplane's flight recorders, computers and parts.

A first operational dive by the Remora 6000 began this morning."

[auv-ee]

The video that accompanies the latest BEA announcement contains brief views of additional photos and sonar records, as well as some good shots of the Remora 6000. My French was never good enough to know whether the interviews contain important additional information.

[kit344]

Question for the experts:

When all pitot data becomes unreliable or invalid, can Groundspeed data from GPS, Inertial, Doppler, etc. be used as an alternate input. Would it be useful?

[BJ-ENG]

Some useful references:

http://www.key2study.com/66web/acns05.pdf

Mobile antenna systems handbook - Google Books (http://books.google.co.uk/books?id=g9DvoOdAQIsC&pg=PA614&lpg=PA614&dq=notch/slot+type+HF+aerials&source=bl&ots=uFcnRtUC4w&sig=NUhEOoMkwu0KaNjpZIsCPAwLNgQ&hl=en&ei=HdO2TdyvN4Kz8QPdr)
YFS&sa=X&oi=book_result&ct=result&resnum=7&ved=0CFIQ6AEwBg#v=onepage&q&f=false

[Bahrd]

Question for the experts:

When all pitot data becomes unreliable or invalid, can Groundspeed data from GPS, Inertial, Doppler, etc. be used as an alternate input. Would it be useful?
Yes: Airbus submits patent for airspeed error monitoring (http://www.flightglobal.com/articles/2010/01/07/336818/airbus-submits-patent-for-airspeed-error-monitoring.html)

[777fly]

Kit344. Airspeed VS groundspeed?

Certainly, in the B777 simulator, actual ground speed data is available on the ND when air data computer airspeed data is lost due to simulated probe icing problems. There is no reason to suppose that the same would not apply in the real world.
We were using this scenario in a recent series of OPC checks and the GPS groundspeed was an excellent guide to TAS. Note that this might not be of help at high cruise altitude, where a 480 GS/TAS might be achieved at an EAS of about 260kt. A 400kt GS might have you into buffet onset. It's a much better guide below FL100.

[Dehaene]

Hello,

Ile de Sein can be approximately located with this specialized web site:
AISLIVE - IMO search (http://www.subtelforum.com/articles/cableships.php)

[ACLS65]

Dehaene (http://www.pprune.org/members/327650-dehaene):

Hello,

Ile de Sein can be approximately located with this specialized web site:
AISLIVE - IMO search (http://www.subtelforum.com/articles/cableships.php)Hi Dehaene,

I think the Ile de Sein has been out of AIS range for over a couple of days now, so any position shown is probably the last one that was received.

You might want to try this site ILE DE SEIN - 9247039 - Vessel's Details and Current Position (http://www.marinetraffic.com/ais/shipdetails.aspx?MMSI=226235000) it give more detailed info and uses Google Maps to plot the vessels when they are in range. Note under the last position received the Info Received data and time.

[AlphaZuluRomeo]

My French was never good enough to know whether the interviews contain important additional information.
Being a native, mine should be better. :p

Nothing really new. Barely worth mentionning are :

Lead inspector of the BEA: We know where to go first with the ROV to have the maximum possible chance to find the recorders, even if we haven't located them for the moment. But we know where to look for them.

A Phoenix operator & the OC of the Ile de Sein: It will take time, underwater ops at those depths need precise & precautionous procedures, even if we're trained for that.

[MountainWest]

This is the video mentioned by auv-ee. It is 20+ meg, about 3+ minutes.

Sea Search Operations, phase 5 (http://www.bea.aero/en/enquetes/flight.af.447/sea.search.ops.phase.5.php)

Note the chart at about 3:06 in the video. Perhaps someone with a South Atlantic chart can further pinpoint the destination.

[ChristiaanJ]

A remark about 'élingues' ('slings') caught my attention in the French video.... to be used to bring some of the larger parts to the surface.

The Remoras can only pick up small bits and pieces, not entire engines or big fuselage sections.

Unless the recorders are actually lying on the seabed ready to be picked up (unlikely, to say the least), they will either have to 'scratch around' in the tail section, and try to extract the recorders, or use 'slings' to lift the entire tail section, while hoping the recorders don't fall out halfway to the surface....
Said slings having to be put in place first remotely, at 4 km down, by little robots....

I wish them luck, lots of it, and no finger trouble......

[SaturnV]

The Alucia still seems to be out of range. I wonder if it has returned to the site.

[RR_NDB]

Thanks Graybeard, :ok:

A lot of very interesting and new information.

ChristiaanJ, also touched an important topic: EMI/EMC.

will keep learning,

Regards

[ACLS65]

Florida?

Alucia info:

Voyage Related Info (Last Received)

Draught: 4 m
Destination: PORTEVERGLADES
ETA: 2011-04-28 20:11
Info Received: 2011-04-22 05:54 (4d, 12h 31min 39s ago)

ALUCIA - 7347823 - Vessel's Details and Current Position (http://www.marinetraffic.com/ais/shipdetails.aspx?mmsi=356352000)

[bearfoil]

ChristiaanJ

Perhaps the remote operated vehicles can equip the recorders with a proper pinger on their way up in case they fall off the larger assembly....

Turbine D

Many thanks for the rundown on the GE version of Roll's TotalCare. With each TRENT's DEP, it becomes clear why constant monitoring is applied. Inflight tuning of each individual engine on wing begs a babysitter....??

Each engine has its systems, its personality(DEP), and its quirks.....



I think some patience has been injected into this thread as a whole, as I perceive a re-look at some dogma and stubborn opinion, some of it my own. The InFlight a/c is a discrete community, with a culture (micro) that obeys long standing protocol and systems. Communications with the outside world is most often last on any list of priorities. Even 121.5 is no help, before, during and after; no one flying believes a "last known position" will help the cause at all. Other than critical chat between pilots in an emergency, procedures are "trained for", and once alerted and commanded, these procedures are time proven to be executed without questions and fear. Survival is a teamwork thing, and the team is inside the ship, not away. So what has happened aboard 447 is virtually certain to have been done by professionals, well-skilled, and focused on duties, not outcome.

[Machaca]

Some vidcaps and isolations from the latest BEA video:

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap001.jpg

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap001b.jpg


http://i337.photobucket.com/albums/n385/motidog/BEAvidcap002.jpg

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap002b.jpg


http://i337.photobucket.com/albums/n385/motidog/BEAvidcap003.jpg

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap003b.jpg


http://i337.photobucket.com/albums/n385/motidog/BEAvidcap005.jpg

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap005b.jpg


http://i337.photobucket.com/albums/n385/motidog/BEAvidcap007.jpg

Chart is unmarked :(
http://i337.photobucket.com/albums/n385/motidog/BEAvidcap009.jpg

[3holelover]

The major lump in the lower right corner of that first image looks like it could be the APU with most of one of the APU access doors with it...?

[glad rag]

GB et al,

Airbus adopted shunt antennas in the fin from the beginning. I don't know how well they understand the dynamics, but feeding hundreds of amps into a carbon fiber fin makes me wary.

On the 388 the HF shunt sits on the metal leading edge strukture and has [a lot of] dedicated bonding paths/plates on the upper fus to feed back into the HF crate at the [very] aft upper deck.

[Dehaene]

ACLS65:

I fully agree with you that MarineTraffic gives usualy much more information but the site I found is dedicated to cable ships and seems to have data from yesterday (25/4/2011 9:57:28 UTC) with a location close to LKP.

The only problem is that they do not give a precise location.
I could only find pixel coordinates on a global world map by looking at the source code of the web page.

[glad rag]

http://i337.photobucket.com/albums/n385/motidog/BEAvidcap003b.jpg

Hmm would a colour camera/lighting system be of any use in that depth/darkness? Talk about the proverbial needle in the haystack.

[JD-EE]

Slats11, your comment about education and FBW resonates with me when I translate it to terms with which I am intimately familiar.

I to some degree liken FBW to a new radio coming out that links several controls into three or four push button settings. Unless you know what those settings really amount to in terms of the old controls and understand the old controls you cannot wring the maximum out of the radio. Radio manufacturers stepped back a little and more or less gave access to the old controls within the context of the buttons. Newer high end radios have wider selections of filters. And the filters can be tuned, which can substitute for the tricks you used to do with the old controls. But, if you never learned the old controls it still seems to be difficult to extract the best out of the radios.

Looking at FBW in aircraft, unless the pilot knows how to fly the plane to the edges of its envelop without computer interference and unless the pilot knows precisely what steps the computer took before it "gives up" and hands control back to the pilot, it may be hard to recover as the pilot goes back over ground the AP already covered.

I don't know if this is a clear explanation. The extractable information is that I've found computer aiding is helpful; but, you must know intimately what it is doing and has done if you need to wring that last critical bit of (life saving?) performance out of the machinery.

Is there this level of knowledge among the flight crews today?

[JD-EE]

Graybeard and ChristianJ - thanks for reminding me of the slot antenna. In '68 they were still under development as dielectric loaded slots by one of my professors at Univ of Mich. I'd had the impression they were basically designed for VHF at the time.

You got me looking. It's apparently a vertical slot on the lower portion of the VS structure. That would be slightly lower efficiency. But, it doesn't much matter. Communications to DAKAR are possible. And at 6.6 MHz even that antenna would be noisier than any (sane) radio connected to it. This reception is not antenna limited. The pattern might be a problem. I'd expect that always to be a problem rather than specific to AF447's situation. (Does anybody know of a good picture of the antenna unmounted from the aircraft? I'm curious precisely how it is constructed. It's not what I grew up calling a slot antenna. But, with the one picture I have of it, there's not a much better short name for it.)

And finally it bears no importance to the AF447 situation because DAKAR did not have the plane in its list of planes to listen for and Brazil never tried using SelCal when calling the plane. The lack of communications was procedural rather than somehow related to an antenna that doesn't work well.

ChristianJ, those gray patches don't look like the diagrams I have managed to find.

[JD-EE]

Re: Yes: Airbus submits patent for airspeed error monitoring (http://www.flightglobal.com/articles/2010/01/07/336818/airbus-submits-patent-for-airspeed-error-monitoring.html)

Fascinating - for those only worrying about US patents, there is ample prior art in discussion here on PPRUNE to get the patent tossed out.

[ChristiaanJ]

Graybeard and ChristianJ - thanks for reminding me of the slot antenna. In '68 they were still under development as dielectric loaded slots by one of my professors at Univ of Mich. I'd had the impression they were basically designed for VHF at the time.I first came across slot antennas in my early 'radar' days, and that was SHF, and far earlier than '68.

Does anybody know of a good picture of the antenna unmounted from the aircraft? I'm curious precisely how it is constructed. It's not what I grew up calling a slot antenna. But, with the one picture I have of it, there's not a much better short name for it.I'd be interested too, both in seeing your picture, and any others that somebody might have.

ChristianJ, those gray patches don't look like the diagrams I have managed to find.They were more green than gray... I doubt that the slots were 'dielectric loaded'. I think you're just looking at the honeycomb fibreglass covers of the two "sawcut" cavities.

This all being slightly irrelevant to AF447, maybe us 'radio geeks' should open a separate Tech Log thread about HF aerials on airliners?

[HazelNuts39]

Perhaps HN39 might be able to provide a graph of level-flight AoA versus load-factor, please?Sure, here it is: LF vs AoA (https://docs.google.com/leaf?id=0B0CqniOzW0rjMWRlOTE5YzEtOWQ0MS00NzkwLTg0MDAtYzI2MmF jZjYyOGI0&hl=en_GB&authkey=CILo3s8N)

PS: Same data in different format were posted 31st jan 2011, Post #2663 on the previous thread: A330_gustloads (https://docs.google.com/leaf?id=0B0CqniOzW0rjOWIwZGE1ZTItNGFiNi00YzA3LWFlMDktZmM1NzF hMGZmNzUw&sort=name&layout=list&num=50)

[auv-ee]

Hmm would a colour camera/lighting system be of any use in that depth/darkness?

It's not so much the depth and darkness as the basic properties of water. Water absorbs (or scatters, or both) light at the red end of the visible spectrum, and to a lesser extent at the blue end. This leaves a transmission peak for green light, with the overall effect that color pictures, of sunlit scenes, taken at depths of more than a few meters have a strong blue-green tone. (I suppose modern CCD cameras may be able to color correct that to some extent.) This effect is modified by the presence of other things in the water, such as algae and plankton at temperate and polar latitudes. In the tropics, ocean water, viewed from above, looks very blue due to scattering, I think, and is often nearly free of marine organisms. Deep sea water is usually very clear, also.

Electromagnetic absorption by water - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water)

So, in answer to the question, deep sea photos require artificial light, as all sun light has been absorbed. That light is often white, as is the xenon strobe on the REMUS 6000 vehicle, or it could be green (thallium-iodide arc lamp, green LEDs, etc.) to take advantage of the transmission peak and scattering minimum. When photos are taken at close range (both the light and camera close to the subject), as is generally the case for ROV and manned submersible work, color cameras are normally used and the colors look natural, or close to it. When the range is greater, the light that travels from the source to the subject and back to the camera becomes so dominated by blue-green that a color camera adds very little. Furthermore, a B&W camera is usually more sensitive (works with lower light) than a color camera using similar technology, so operation from greater range is enhanced. Modern CCDs have become very sensitive, but in the earlier days of underwater video imaging, intensified cameras were sometimes used, and the intensifier was applied to a monochrome camera.

REMUS would fly at 5-20m (typically 10m) above the bottom for photo work, depending on water clarity and height of possible obstructions. The two-way path length is thus quite long and there is little usable color. If any ROV images or video are released, they are likely to be in color.

The ultimate range of underwater imaging is usually limited by back-scatter from the water and the particles in it, which fogs the image. That is a large topic, not related to the question, but I thought I should mention it.

As a side note, I expect that the visible spectrum (spectrum of light visible to humans) is so narrow, being less than one octave from about 400-700nm, exactly because of the absorption properties of water. Either because our retinas are sensitive to the light that gets through our water-filled eyes, or possibly because the type of eyes we have evolved in water dwelling lifeforms. There is probably known science on this, I'm just not familiar with it.

[kilomikedelta]

I suppose I opened a bit of a hornets' nest with my comments regarding RF communications by AF447.

I'm a radio amateur and not a radio professional so my observations are based on empiricism but I believe that electromagnetic propagation is still a poorly understood science (not only by me) and at times will not conform to engineering specifications.

My object was to point out the perversity of inanimate objects such as non-vacuum electromagnetic propagation media (and in previous comments - computer software) as observed by Major Edward Murphy and published by his colleague Col. John Strapp M.D. who understood the medical maxim: never say that something never happens or that something always happens. This applies to all professional endeavours.



AF447 foundered is spite of the collective wisdom of all who created and operated her.

[RR_NDB]

"maybe us 'radio geeks' should open a separate Tech Log thread about HF aerials on airliners?"

Considering:

1) Crescent EMI/EMC challenges (High RF pwr near sensitive front end circuitry).
2) A clear room for performance improvement
3) A probable "extra life" for HF
4) The passion for the issue :ok:

Why not to open it asap?

[bearfoil]

I would modify your maxim to wit. 447 was lost perhaps because the collective was not complete, or some of it was insufficient or incompetent.

This was not an act of GOD. This was a failure(s) that killed people. If we knew it to be a fluke, and nothing was to be found as to cause, there would be no Phase 4, or 5. IMO.

[RR_NDB]

Hi, KMD OM

Here is Charlie Whiskey, (not OM like you, just 60), hihi

Let´s develop a thread on the issue?

[RR_NDB]

Some years ago i faced a challenging noise filtering issue so difficult i finally drastically changed the original design.

HF pick up by yaw damper in a supersonic a/c remembers me the space " butterfly region" of stones in spacecrafts flight path.

Very dangerous issue and a real threat to dense circuitry.

[kilomikedelta]

Bearfoil;

That is my point. I believe everyone put their best effort into designing and operating that A330 but conditions unanticipated by software writers, a dielectric black hole that swallows RF or shortcuts to improve the bottom line will eventually bite our buttocks.

It's all a teaching and learning experience we should not ignore.

Cheers

[RR_NDB]

GB

Could you comment something on Signal strenght (pwr out) with new ones comparing to the old wire antennas? (not trailing wire)

[RR_NDB]

"The proposed airspeed monitoring system would compare changes in measured airspeed over a short period of time with changes in ground speed as computed by the accelerometers and gyros in the aircraft's air data and inertial reference unit (ADIRU)."

If goes fast to "public domain" will be fine

[RR_NDB]

Links to see the design?

[Pugachev Cobra]

An English transcript of the video published on April 26 is now available at the BEA site:

Start of phase 5 of the sea search operations, English transcript (http://www.bea.aero/en/enquetes/flight.af.447/debut.phase5.transcript.php)

[BJ-ENG]

Is this one of the underfloor support members?

If so, it gives an idea of scale.

ImageShack® - Online Photo and Video Hosting (http://img841.imageshack.us/i/beavidcap003bmod.jpg/)

[sensor_validation]

"The proposed airspeed monitoring system would compare changes in measured airspeed over a short period of time with changes in ground speed as computed by the accelerometers and gyros in the aircraft's air data and inertial reference unit (ADIRU)."

From the published US patent application

[0007] Generally, aircrafts comprise systems comparing between them the information provided by different sensors. Thus, if most of the sensors provide a similar value, such a value could be considered as true. However, in some cases, being actually very rare, such sensors could be, either all or most of them, submitted to a similar frost phenomenon, so that the systems of the aircraft and the pilots can be without any reliable indication about speed or be unable to eliminate the erroneous speed(s).

The incorporated French patent submitted Sep 23, 2009

[Chris Scott]

HN39.
Thanks for the LF/AoA graph. Thought you would rise to the small challenge!

Fascinating discussion on HF antennae and propagation, chaps... Yes, Graybeard, think the VC10 also achieved whole-airframe antenna from its fin-mounted thingy. Whereas the B707 just had the antenna sticking forward from top of fin. Aft reception could be difficult in my experience on some aeroplanes, but can't remember which ones of VC10, B707, A310, or DC10. Pretty sure the VC10 is better than B707 in that respect. Aerial-tuners also used to be a problem sometimes, leaving you with the inability to transmit. Changing freq sometimes solved the problem.

Re VHF-AM in static, I'd just like to point out that ear-splitting static often accompanies St Elmo's fire.
　
Re Airbus's proposal (http://www.flightglobal.com/articles/2010/01/07/336818/airbus-submits-patent-for-airspeed-error-monitoring.html) of using GS as a way of checking the veracity of sudden indicated-airspeed changes, the Flightglobal report quotes Airbus as saying:
"While airspeed and ground speed can not be compared directly, Airbus notes that over a "very short period", normally significant factors like windspeed, changes in altitude, air temperature and angle of attack will be negligible, allowing for a direct comparison of changes in speed rather than speed itself."

I wonder what "very short period" they have in mind. By definition, large aircraft never experience rapid changes in GS. IAS/CAS, on the other hand, changes very rapidly in gusts. In the different situation of entering a jetstream from the side, the tailwind-component (for example) can increase by 100 kts in two or three minutes. This leads to a steady loss of IAS, which has to be recovered by climb thrust to build kinetic energy until the GS has been increased by the 100 kts.

On walk-rounds, I sometimes pondered on the positioning of the three probes. #1 & #2 are usually symmetrically positioned; #3 usually near #1. All seem equally susceptible to icing. But is it only the shape of the probe itself that matters?

Another point: can't someone invent an even more powerful heater that could kick-in as soon as a sensor/camera shows the beginning of ice formation? On the VC10, we had an ice-probe visible under the captain's DV window. It had a light which enabled the captain to inspect it with mark-1 eyeball, and a heater to de-ice it. (If it was icing up, we would put the airframe anti-ice on.)

Wouldn't it be nice if pilots could actually SEE their pitot tubes?

[RR_NDB]

Chris Scott,

I will analyze the HF antenna design of VC10, initial DC10 and the poor ones like in 767.

Will be a pleasure to do that.

Aft reception: When your antenna is at a/c tail you have a "ground plane to the front of it" making RX and TX much better than to the back of the a/c.

Just to brief you on the theory: if you drag a wire, bonded to fuselage, the aft sigs would be the same to the front. Better if the wire is quarter wavelenght of the operating QRG. In this case the antenna would be in the middle, symetrical (fuselage to the front and trailing wire to the back).

On St Elmo and static poor RX this could only be solved increasing the power out of ground station but unfortunately the days of the 12ACX and 4WTFA are gone. They are using lower power and this is an error. I will investigate the current power levels and antennas being used in DKR, REC and others.

I designed and used several antenna tuners and at certain QRG they simply don´t tune. (for a given antenna type). And frequently sparks due VERY HIGH voltage.

On trailing antennae see the one of E6 Tacamo:

Boeing: E-6 Tacamo - History (http://www.boeing.com/defense-space/ic/e6tacamo/history.html)

Trailing a wire roughly the same lenght of cruise FL, 30,000 ft.

The antenna is a dipole (end feed, similar to the one used in Zeppelin) and the radiating element is another wire, a short one. (~5,000 ft), feeded with a coil in the a/c antenna tuner.

The purpose for this is to put a signal to be received by a submarine. (E6 orbiting) in this case the dipole (horizontal) radiates to sea, sides an top of the a/c. For a ONE WAY comm to the sub. (Sub just in RX mode)

QRG around 17 KHz (under 20 KHz).

:)

[jcjeant]

Hi,

From not far from here (Internet is a small world :) )

Google Vertaling (http://translate.google.be/translate?u=http%3A%2F%2Fhenrimarnetcornus.20minutes-blogs.fr%2Farchive%2F2011%2F04%2F27%2Fdeep-trouble.html&sl=fr&tl=en&hl=&ie=UTF-8)

While a family of victims of the accident of Flight 447 has filed a lawsuit against BEA to "obstruction of the truth", we recall here again that the assumption of "stalling" of the 'At 330, if it had been made, would have led BEA to conduct searches of the wreck under the last known position (LKP) at the outset of the investigation

Original:
« Deep trouble » pour le BEA (http://henrimarnetcornus.20minutes-blogs.fr/archive/2011/04/27/deep-trouble.html)

[bearfoil]

BJ-ENG

I think you are correct. Of the two decks, I think you are looking at the cargo floor (member). The Cargo floor, though shorter in span than the pax deck, also has 'bridging' to support the floor, while the pax deck is clear span. The piece of bridgework that remains attached to the floor member is relieved as the pic shows it would be. Also, there appears to be a remnant of fuselage frame remaining, so this piece would be located at the area where the cargo floor and fuselage mated. ??

Captain Scott

Last look I had at the 300 family, (A300) last August, there was a fourth pitot probe on the port side, is this a new addition? Is the A330 newly configured this way??

jcjeant

The Airbus cannot Stall, and it cannot come apart at altitude, So the BEA has reported as these truths imply: "Enligne de Vol" There is no need for looking directly under LKP, or within 40 nm for that matter. :uhoh:

[RR_NDB]

JD-EE

At page 7 in the link below there is a good text on the issue.

Slot antenna (http://www.freepatentsonline.com/6982677.pdf)

[CONF iture]

Thanks for the link (http://henrimarnetcornus.20minutes-blogs.fr/archive/2011/04/20/le-decrochage-d-airbus.html) jcjeant.

En ligne de vol ...

http://i25.servimg.com/u/f25/11/75/17/84/af447_10.png (http://www.servimg.com/image_preview.php?i=82&u=11751784)

For sure there has been AMS, but also Perpignan, and maybe AF447 ... ?
I find it peculiar Airbus is using a 737 profile to demonstrate the brand new procedure to survive a stall ...

[milsabords]

Vol Rio-Paris: le châssis d'une des boîtes noires retrouvé - Yahoo! Actualités (http://beta.fr.news.yahoo.com/vol-rio-paris-ch%C3%A2ssis-dune-bo%C3%AEtes-noires-retrouv%C3%A9-141114710.html)

[bearfoil]

No matter. What I want is to hear these two (or Three) pilots as they try to keep this heap in the air, after it has done its ignorant best to dive into the sea.

It will reclaim for them their heroism, and the shocking lack of dependability of this a/c on that date.

The wreckage is the key, and soon the lightbulbs will pop, as folks "piece" together how this happened.

Boxes optional.

There are two salient issues to remember, and these have not been addressed.

"There was NO evidence of forward momentum" (Horizontal, but 'backward'?)

What is MISSING from this "debris field"?? (Second engine? Wing parts?)

[ChristiaanJ]

"Le chassis" (in the French text) may refer to the 'mounting rack', not to the FDR unit itself.
It's what I was afraid of... the recorder(s) being ripped from their mounting racks (not necessarily designed to the same crash-resistant standards as the recorders themselves), and making their own way to the sea bottom, and getting buried in the silt....
Good luck, guys...

Edit: Ignore, please. I've now seen the photos, and that's obviously the recorder unit, not the 'mounting rack'. Not sure whether the photos show the CVR or the FDR, though.

[Chris Scott]

Quote from the piece referred to above by jcjeant (English translation of the original French):
"... BEA has never considered the possibility of "stalling".
…BEA has never contemplated that the A 330 could have come out of its flight. The BEA, however, only determined the search area according to the inverse hypothesis that "in view of the maximum possible speed of the aircraft, the wreckage of the plane had to be in a circle of 75 km radius (the circle) centered on the last reporting point position (LKP) "(Mr. TROADEC note of 8 April 2011).
"Deep trouble" for the BEA.

Only fair, I think, to point out the source of these accusations. It's a website called "Les Dossiers Noir du transport aérien" (Air Transport's Black Files), a "Blog citoyen d'un ancien commandant de bord" (Citizen's blog by a former airline captain).

One or two names spring to mind... As far as I'm aware, the accusations made are nonsense.

How can the writer say that the BEA has never contemplated stalling or departure from flight envelope ("sortir de son domaine de vol") ?

How can it be wrong for the BEA to define a circle of radius 75 km (40 nm) from the LKP as the search area? To my knowledge the BEA has never stated that the accident could not have taken place at or close to the LKP. (We still don't know where it happened, but that's another matter.) If they had defined and searched smaller circle, and the debris had turned out to be outside it, would that have led to another version of this conspiracy theory?

With the benefit of hindsight, the apparent failure to search closer to the LKP in Phase 3 looks unfortunate, but the difficult search seems to have been prioritised in the areas of highest probability. Eventually, the two search vessels (Anne Candies and Seabed Worker) simply ran out of time last year.

To accuse the BEA or any other organisation of deliberately ignoring the most likely site of the debris is preposterous. In any case, they would have known that the industry would never let them get away with it long-term. However frustrated the interested parties are with the delay in finding the main debris field, and however much we would all like to have unrestricted access to its progress, it seems to this amateur observer that the BEA is supplying a similar amount of information to that which has been disseminated in other investigations of comparable complexity.

[ChristiaanJ]

I find it peculiar Airbus is using a 737 profile to demonstrate the brand new procedure to survive a stall ...Don't be silly, JAM. To draw such a diagram, you borrow from a generic database of shapes.
And not all aeronautical engineers are fervent 'spotters', you know?
To me, all them Coke cans with two engines look the same. Personally I can only just distinguish between the big 'uns and the small 'uns, and usually the only way I can pick out a 737 from the crowd of little 'uns is from the squashed nacelles.

[CONF iture]

BEA Information - APR 27
During the first dive by the Remora 6000, which lasted over twelve hours, the chassis of the airplane's Flight Data Recorder (FDR) was found, though without the Crash Survivable Memory Unit (CSMU) that contains the data. It was surrounded by debris from other parts of the airplane.

The searches are continuing. A second dive by the Remora 6000 began this morning.


http://i25.servimg.com/u/f25/11/75/17/84/chassi10.jpg (http://www.servimg.com/image_preview.php?i=83&u=11751784)


http://i25.servimg.com/u/f25/11/75/17/84/chassi11.jpg (http://www.servimg.com/image_preview.php?i=84&u=11751784)

[jcjeant]

Hi,

Quote from the piece referred to above by jcjeant (English translation of the original French):

I can agree on some of your points
Anyways ... do you read once "stalling" in the two preliminary BEA reports ...
I read this word many times here in Pprune .. not in BEA prose ...

[bearfoil]

Captain

I think you are missing something, and in doing so, appear to be sliding into what you yourself have bemoaned. This is not adversarial to the extent of being fatal to any argument. There are POV's as well as ROV's.

BEA is a closely connected agency with the principal interests in French Aviation. If you wish to promote the view that all is objective, independent, and scholarly to the exclusion of bias, we should talk.

If however you take the view that there is a history of adversarial and parochialism re: these issues, no harm, no foul.

It is legend that aircraft carry with them certain reputations. Are "Experts" hobbled with some of these prejudices?? Of course. LKP was the beginning of the problem, and the airbus cannot fall straight down, nor can it lose bits, so "we" plan accordingly, and perhaps reject preliminarily some critical data.

[infrequentflyer789]

The Airbus cannot Stall, and it cannot come apart at altitude,


It's a plane, of course it can stall, saying it can't is like saying a t-tail with a stick-pusher "cannot stall". Both cases just have a bit more protection from stall - break or disable those and stalls happen (proven in past incidents)

As for coming apart at altitude, also already proven to happen (just need enough range on a SAM)


So the BEA has reported as these truths imply: "Enligne de Vol"


En Ligne de vol does not mean flying. The report with that phrase in clearly also shows it was falling like a brick, with low forward speed, but it happened to impact in a flight attitude. How ? Who knows, maybe jsut luck, maybe flat spin or similar


There is no need for looking directly under LKP, or within 40 nm for that matter. :uhoh:

But they did look at LKP. The first air searches (supposedly) did so, and found no wreckage, and the first pinger searches also covered that area and came up blank IIRC. This latest successful search was going back over old ground, not searching new areas.


Now, if you want to do the real conspiracy theory, what is they logical conclusion if at the fourth time of looking you find something right where you looked the first time and didn't find it ? How long would it take to create convincing fake recorder data (they've done that before, right ?) and chop up enough bus bits and drop on them the bottom ? A year or so maybe ? And for the clincher, why aren't there any public photos of recognisable bodies or personal effects ? - because they wouldn't be there in a fake wreck! :E

[captplaystation]

Sad to say, but what volatile fuel for the conspiracy theorists, casing but no memory module :hmm:

[Graybeard]

Thanks for the link, RR. That same Brit ex-pat, Ben Hornby, consulted with the inventors of this antenna. It must have been his last project.

They have also built a slot antenna for the 747-1 and -2.

The spec for the DC-10 antenna is nmt 8 milliohms, while for the 767 it was on the order of 35 milliohms. Divide that into 400 watts, and you see the difference in efficiency.

[Chris Scott]

jcjeant and bearfoil,

Interim Reports are, as I understand it, an attempt to supply information on known facts; not to indulge in theories. We can do the latter because we owe no responsibility to anyone except ourselves. The BEA does not have that luxury.

In their analysis of previous instances of unreliable airspeed indications, they discuss the instances of stall warnings (and criteria for same) at some length.

On a slightly different note: I subscribe to the theory that, if anything goes less than well in any human activity, it's generally due to what we Brits call "cock-up" (a shooting term) rather than conspiracy. I refer, of course, to the investigation; not the accident.

Granted that a lot is at stake here: not only for Airbus, Air France and the BEA. We will continue to try and keep them all on their toes, directly or indirectly. As for my own meagre (and sometimes flawed) contributions: my previous years of posts frequently include fundamental criticisms of Airbus design, as CONF_iture can tell you.


PS (Edit)

bearfoil, quote:
"Of course. LKP was the beginning of the problem, and the airbus cannot fall straight down, nor can it lose bits, so "we" plan accordingly, and perhaps reject preliminarily some critical data."

That's quite an accusation. I think you should tell us what data you are referring to.

[777fly]

CONF iture:

A pitch up/down moment in response to power changes is always to be expected in a conventional aircraft. However, the A330 is a 'fly by wire' aircraft and as I understand it, pitch changes with power are 'ironed out' by the fly by wire system. For example, on the B777, also fly by wire, the a/c has to be positively rotated into a climb attitude on a go-round, as the natural pitch up is removed by the PFCs. If AF447 was in a degraded flight control mode, the crew may have encountered an entirely unexpected pitch change, with power change, if they inadvertently entered a CB.
It is encouraging that the FDR module, although missing the CSMU, is not buried in silt to any extent. I do not see any footprints or scrape marks around the the FDR housing, so not much for any conspiracy theorists to go on.

[deSitter]

Recorder but no memory module - isn't this unprecedented??

And to ChristaanJ, I surely hope you have better girl-spotting skills than planes :) The A330 is a catfish - the 777 is a horizontal spacecraft!

[jcjeant]

Hi,

Regretable that we have not another photo of this frame after it is moved by the ROV ... because the part supporting the memory module is partially buried in mud ...

http://i55.tinypic.com/2pq3pcl.jpg

[glad rag]

777fly yes I think that we should try and remain upbeat for the moment, still a bit of a blow though.

I think they will eventually find it, as you said it hasn't sunk into the silt at all.

[MountainWest]

Now that AF447 has been located it is easy to ask: "Why didn't you just look there in the first place and save all that time, trouble and money?" Regardless of when or where or whether the wreckage was found, there were bound to be accusations of "too close, too far, too much, too soon, too complete . . . " If the problem had been easy it would have been solved a long time ago.

It is good the authorities have involved recovery resources from multiple agencies and nationalities. Regardless of the outcome of the investigation there will be conspiracy accusations. Anomaly or even completeness will be seen by some as "evidence" of a coverup. The more BEA involve independent participants, the less likely the accusations are to resonate with the public.

If the problem had been easy it would have been solved a long time ago.

[jcjeant]

Hi,

I hope .. the families will have now the answers to their questions .....

Google Vertaling (http://translate.google.be/translate?u=http%3A%2F%2Fwww.asso-af447.fr%2FBEA%2Freunion-du-5-octobre-2010-au-ministere-des-transports.html&sl=fr&tl=en&hl=&ie=UTF-8)

Original:
Réunion du 5 octobre 2010 au ministère des transports | BEA (http://www.asso-af447.fr/BEA/reunion-du-5-octobre-2010-au-ministere-des-transports.html)

[SaturnV]

I am a bit confused by this discovery. I thought that the Alucia had photomapped the entire wreckage area (thousands of photos) and no sign of either recorder, and thus the supposition was they were still in the tail.

Did the Alucia miss this recorder, or is it now being seen because the Ile de Sein moved a piece of wreckage that was obscuring it?

[Chris Scott]

Quote from 777fly:
"It is encouraging that the FDR module, although missing the CSMU, is not buried in silt to any extent. I do not see any footprints or scrape marks around the the FDR housing, so not much for any conspiracy theorists to go on."

I wonder at wahat stage the "module memoire" broke away from what they call the "chassis". At sea-level impact or when the chassis hit the sea bed?

Seem to remember someone came up with a suggestion on this thread that a long streamer might be attached to these modules in the future...

[AlphaZuluRomeo]

@ SaturnV : IIRC Alucia vehicle glided "far" (~10-15m) above the sea bed.

Look at the picture, imagine what you would see from this same part (recorder casing) on a pic taken vertically from 10m high ?
I'm not sure if the previous pics (phase 4) were in colours ? If B/W pics, it's even harder to notice that part as "interesting".

@ Chris Scott
"Il s'est désolidarisé sans doute sous l'effet de l'impact" avec la surface de l'eau, a expliqué à l'AFP le directeur du BEA, Jean-Paul Troadec
quote from Le Monde (here (http://www.lemonde.fr/societe/article/2011/04/27/vol-rio-paris-le-chassis-d-une-boite-noire-retrouve-sans-les-donnees-du-vol_1513701_3224.html))
Rough translation = the BEA director thinks the memory module broke apart when the plane impacted water.

[snowfalcon2]

Recorder but no memory module - isn't this unprecedented??

No. In the ET409 accident, i.e. the Ethiopian B737 which came down in the sea after takeoff from Beirut on 25 Jan 2010, the CVR memory module had separated from the chassis. It was reportedly found at a later stage.

[Machinbird]

I wonder at what stage the "module memoire" broke away from what they call the "chassis". At sea-level impact or when the chassis hit the sea bed? No. In the ET409 accident, i.e. the Ethiopian B737 which came down in the sea after takeoff from Beirut on 25 Jan 2010, the CVR memory module had separated from the chassis. It was reportedly found at a later stage.Is it just me, or does this seem like a Delta Sierra design for any crash recorder? It might make sense if there were 20 of these memory units scattered about the aircraft, all with mirrored copies of the data, but like this? Why have a big orange painted box of no value to the investigation, and a small coke can containing the "crown jewels" perched on a shelf of the large box where it can be knocked off the "shelf" and make its own trip to the bottom? If the memory module is not buried in the silt under the big box, you can bet it broke loose at the water interface transition.:{ And from the second quote, it appears they already had one object lesson.:mad:.
And this accident was probably only ~ 1/40th of the peak possible crash energy!!!

[KTVaughan]

If the FDR is that beat up, this might explain why the pinger was never detected...........

[snowfalcon2]

If my memory is correct, the pinger (locator beacon) is attached to the memory module rather than the recorder chassis. (Applies to both FDR and CVR of modern design).

It would be a logical design choice, but it would also imply that the pinger power supply batteries are housed in the same module, making it a comparatively heavy item which is more likely to drop straight down to the seabed than, for example, other parts that are mostly aluminium sheet construction.

The BEA must have all this already figured out, of course. Hopefully the memory module and the CVR are soon found.

[gums]

Salute!

As promised, I shall refrain from speculation on "causes" and "design" of the plane.

OTOH, fer jeeez friggin' sake!!!!! The "memory" is not encased in a stainless steel/titanium "crash survivable" container - like the the DFDR itself, and is attached to the OUTSIDE of the neat, orange qizmo!?! BEAM ME UP!!!!

Oh well, we had really good data from the Columbia breakup, and that sucker went thru a lot more heating and forces than the AF jet. Had some great stuff from the Buffalo loss of control crash. Decent stuff from the Airbus back in 2001. Hmmm.

And what is that beer can doofer at 1 o'clock in the pic?

[RR_NDB]

Hi, Graybeard

I will design ASAP an HF antenna based in ideas developed during our discussions.

I will field test it in my RV where i currently use a moving pole plus trailing wire with SUPERB performance, ranging from 1.5 ~ 18 MHz rated 500 W rms. I operate it with a manual tuner assembled with the best material (MIL STD) used in old birds.

But the moving and the height above the motor home presents an extra load to my "crew" and we hit telephone wires and trees sometimes.

Now we must concentrate in the AF447 issue that will be heating up with the recent findings.

Thanks for the motivation you gave me to further study an issue i was interested since 1965 and is one of my passions. HF comm.

[sensor_validation]

And what is that beer can doofer at 1 o'clock in the pic?

Its the pitot tube sticking out of the bed at 12-O'Clock (with shadow) that leaps out at me...

http://www.bea.aero/fr/enquetes/vol.af.447/images/chassis.fdr.site.jpg

[jcjeant]

Hi,

tube .. maybe ... but pitot ???????
Notice the very good physical state of the box ! .. no evident corrosion .. etc ...
That's a good premise for the other items that will be recovered as evidences for investigation.

[SaturnV]

Why is the memory unit fastened outside the chassis (storage box)? Surely, there must be a design rationale for doing this.

I assume the same design for the CVR as well.

So we have a description of a tail section supposedly sufficiently intact that the recorders are first thought to be inside that section. Now, there is at least one recorder that apparently separated on impact, and the impact forces also dislodged the memory module from its external mounting.

Only saving grace at this point is that the plane settled on a flat plain, and not on the slope of a crevasse.

[Flight Safety]

Upon examination of the Honeywell link that PJ2 provided, it appears the crash survivable memory unit (CSMU) and the DFDR chassis are designed to separate. The Underwater Locator Beacon (ULB) is attached to the CSMU, and thus designed to stay with that unit in the event of chassis separation.

[TOM57]

BEA says that the area where the plane was found had been researched in the early phases by sonar. Nothing was detected then, and that is why they had privileged other sectors in later searches.
In French:
Les recherches de détection acoustique des balises installées sur l’avion, et
devant émettre un signal pendant 30 jours au moins, ont donc eu pour objet
d’explorer en priorité la zone se trouvant le long de la trajectoire prévue de l’avion
et, en fonction du temps et des ressources disponibles, la plus grande surface
possible du Cercle. La zone où l’épave a été découverte avait donc bien été
explorée par ce moyen, sans détecter les balises. Les raisons de cette non détection
vont maintenant être recherchées.
http://www.bea.aero/fr/enquetes/vol.af.447/note.du.directeur.fin.de.la.phase.4.pdf

It is said that they don't know why the pingers where not detected and will have to look in to this.

Thanks for this great thread!

[ChristiaanJ]

gums,
The memory module IS supposed to be "crash survivable" on its own. Whether it parting company with the rest of the recorder assembly was also sufficiently considered is now an open question....

[mm43]

It appears that the mounting plate for the CSMU on the DFDR chassis has suffered some deformation, and there is stress indication which looks like the CSMU securing bolts have been dragged through the mounting plate.

The CSMU/ULB will not be too far away, i.e. the combo will be a straight down unit, but mass/volume means their landing will not have been soft. The silty bottom indicates to me that some technique other than visual will be needed to find them

[ChristiaanJ]

And to ChristaanJ, I surely hope you have better girl-spotting skills than planes :) The A330 is a catfish - the 777 is a horizontal spacecraft!No trouble with girl-spotting, LOL.
And many many years ago I did win a local plane spotting competition, but that was still in the days where there was a difference between a Comet and a 707 or a DC-8, or between a Sabre and a Hunter....

[Graybeard]

The 777 is a 737 on steroids.

[NeoFit]

It is not the main subject, but somebody is interested in the aerial for décametric waves, here (http://www.qsl.net/pa0sny/SNY-AM%20A330%20details.html)is some information and a photo of the leading edge of VS (http://www.pilotlist.org/dispo/jd8/42Pied_de_derive.jpg).

One of the recorders is located in the rear part (http://www.pilotlist.org/dispo/jd8/41Cadre_arri%e8re.jpg) of the plane.

[CONF iture]

Raw data please, not your TV brand !
We are curious here ...

http://i25.servimg.com/u/f25/11/75/17/84/chassi10.jpg (http://www.servimg.com/image_preview.php?i=83&u=11751784)

[DozyWannabe]

BEA says that the area where the plane was found had been researched in the early phases by sonar. Nothing was detected then, and that is why they had privileged other sectors in later searches.

While this isn't directly pertinent to the subject, I've got to say that there's major irony there. When the joint French/US team went looking for the Titanic in 1985, their starting point was the last sonar return not explored by Jack Grimm's expedition. As soon as the sonar scan started, the returns were so wild that they figured it must be a technical malfunction and brought the sonar device back up for recalibration. They then proceeded to spend weeks scanning the rest of the search area, finding nothing. It later transpired that while the sonar readings were fluctuating wildly at the beginning of the mission, some of the returns were true and they were in fact practically on top of the wreck site. Every pass they made in the following weeks took them further and further away from the target.

The US half of the team (having been away on what turned out to be a clandestine mission to film the USS Thresher and Scorpion) then put all their chips on sending the video cameras down at the starting point and found the wreck site with barely a couple of days to spare.

Deep-ocean exploration and salvage - possibly one of the hardest things in the world to get right!

[bearfoil]

infrequent, captain scott

"lingue en bouche, s'il vous plait..."

Tongue in cheek. I don't believe in faked evidence, avoiding duty, stolen flight recorders, check that last......

I believe in bias, corporate and political games, and advantaging one's friends. Not outright criminal, ok?? Until it is past time, friends get the benefit of the doubt, mine do, how about yours??

guppies that rupture after going deferred for five thousand cycles??

Mon Dieu!! Pitots that freeze and tell lies??? How many times was that, you know, before 228 people died and the pilots did a labor action?? Now listen, I believe in scepticism, harsh and unabashed. There are no mistakes in aviation, not lately. What gets trumpeted as "bad luck" is some butthole with a calculator convincing the Board it's ok to stretch service life, and hire students for complicated machining. Rudder jacks freeze, Computers go bananas, and people die. Pretending we're still at some frontier in a desperate game with physics is nonsense, we can make and fly aircraft that are levels above the current iteratae, and make a living too. Playing the fools game with wizards who do this s..t for a living is not productive.....Other than that, it is nice to see so many people still interested in this drama; I believe it may be a modern record.

Don't order the chicken pot pie........

[DozyWannabe]

infrequent, captain scott

"lingue en bouche, s'il vous plait..."

Tongue in cheek. I don't believe in faked evidence, avoiding duty, stolen flight recorders, check that last......

I believe in bias, corporate and political games, and advantaging one's friends. Not outright criminal, ok?? Until it is past time, friends get the benefit of the doubt, mine do, how about yours??

guppies that rupture after going deferred for five thousand cycles??

Mon Dieu!! Pitots that freeze and tell lies??? How many times was that, you know, before 228 people died and the pilots did a labor action?? Now listen, I believe in scepticism, harsh and unabashed. There are no mistakes in aviation, not lately. What gets trumpeted as "bad luck" is some butthole with a calculator convincing the Board it's ok to stretch service life, and hire students for complicated machining. Rudder jacks freeze, Computers go bananas, and people die. Pretending we're still at some frontier in a desperate game with physics is nonsense, we can make and fly aircraft that are levels above the current iteratae, and make a living too. Playing the fools game with wizards who do this s..t for a living is not productive.....Other than that, it is nice to see so many people still interested in this drama; I believe it may be a modern record.

Don't order the chicken pot pie........



:confused:

[bearfoil]

dozy

Take everything you see and read with a grain or more of salt.

Happy skies.

[RatherBeFlying]

Detached by the Impact

"It was surrounded by debris belonging to other parts of the airplane" added the BEA [informant]. "The protected container or memory module is normally attached to the chassis. But this module is much heavier than the chassis. No doubt it came apart from the impact" with the surface of the water, explained to AFP the Director of BEA, Jean-Paul Troadec. "The container has a much greater force of inertia, it is quite possible that the container followed a different descent trajectory than that of the châssis because of currents", he explained further.Sounds perfectly reasonable to me.

I would propose obtaining a similar recorder and memory module to chuck over the side to see where they end up -- how far apart and bearing would be useful.

Well it would be considerably cheaper to remove the expensive innards of the boxes, add pingers and ballast to bring the weight back to spec before chucking overboard;) Don't forget to bend the chassis frame the same as the original.

[777fly]

Graybeard: The 777 is a 737 on steroids

I'm not too sure what you mean by that. The B777 is certainly a big aircraft, but the fly by wire gizmos make it a very benign flying machine, with far better handling characteristics than a B737. Boeing got the B777 right, straight out of the box, and were quite right IMHO to leave ultimate control in the hands of the pilot, not a possibly deluded box of tricks.

[3holelover]

Bearfoil... one day, the bean counters will understand the costs of an accident exceed the costs of safety.

[Graybeard]

Sorry, 777Fly. I meant, on the ramp, the 777 "looks like" a 737 on steroids. My post followed another along the same line.

[jcjeant]

Hi,

it is quite possible that the container followed a different descent trajectory than that of the châssis because of currents", he explained further.

This does not seem to bode well .. if BEA has again evoked currents ....
We know what happened with the study thereof in other phases of research .... :eek:

[Pugachev Cobra]

I really hope they do retrieve back to the ship the FDR chassis.

Can you imagine letting it on the deep, and by some unfortunate coincidence the memory module is actually inside the chassis?

The last place they would expect!

Now really, it's a serious professional investigation, I'm sure they spent at least an hour of the 12 hour of the first dive circling and moving the FDR chassis.

[JD-EE]

Two pictures. (http://www.bea.aero/fr/enquetes/vol.af.447/info27avril2011.en.php)

[JD-EE]

OTOH, fer jeeez friggin' sake!!!!! The "memory" is not encased in a stainless steel/titanium "crash survivable" container - like the the DFDR itself, and is attached to the OUTSIDE of the neat, orange qizmo!?! BEAM ME UP!!!!


OK, the memory module is what is packaged to survive the apocalypse. The rest is the electronics that feed that little bit of memory. If the memory module sticks to the chassis that is nice. If it breaks loose there was enough stress that it might have broken rather than come off whole if it had been secured better.

Come to think of it, if the memory module separates easily it cannot get corrupted by the death spasms of the electronics module. It may have been designed to detach fairly easily for that reason.

Wikipiddle has some pictures that might help you see what is going on. But the one shown with three main pieces should do it, electronics chassis, memory module, and pinger.

[JD-EE]

NeoFit, thanks lots for that picture. It clear up just a whole lot.

I'd not call that a slot antenna. There's no slot. It function as a form of loop antenna with part of the wire really wide and the other part merely wide. It would be relatively low loss at RF. And the feed point impedance is apparently .035 ohms. I wonder if the conductors are silver plated for best efficiency. That's into a region that ought to match and work pretty well. (And it appears it's short enough resonance is not an issue until fairly high frequencies 15-20MHz.) As a loop it MAY favor radiation to the sides, though. That may not be good. the good thing for it being a loop is it's virtually immune to static electricity.

Anyway - thanks for the picture. It clarified for me "where the current is going."

[Machinbird]

If the "beer can" is much denser than the chassis, they should look back to the East of the Chassis location to have a hope of finding it. At the surface, the two items were initially together. As they settled to the bottom, the lighter chassis took longer to fall and was carried further to the West. We are about to see a practical application of the density sorting concept.

From the internal description that MM43 provided a link to, you have the memory chips surrounded by a thermal mass, which is then surrounded by insullation, which is then surrounded by an armoured shell. So why are the attaching feet on the memory module so small? It looks like a few whacks with a hammer would break them. The pinger module also looks like it could easily be sheared off the memory module. It really seems that they took weight savings to a ridiculous extreme in designing the unit and now it is a problem. As accident impacts go, the AF447 impact with the surface was relatively light.

[Mr Optimistic]

Can you have 'loose silt' under that pressure of water ? Even the engines weren't that dug in. Gives hope for finding the parts.

[henra]

Can you have 'loose silt' under that pressure of water ? Even the engines weren't that dug in. Gives hope for finding the parts.


Theoretically you could have. The pressure applies on all sides where it touches an object. As the individual sand particles are not sealed watertight the pressure will also apply from below.
However, I agree it looks that the bottom is rather solid. The debris shown so far in the images is not buried at all. Especially even the heavy items like engines, gears etc.
So I'm also confident that the memory module hasn't been buried significantly.
On the other hand I'm also a bit at a loss why design a nice bright orange box of very specific shape and then loosely attach the important part as a rather small unremarkably shaped can onto it instead of including it into the box making the latter somewhat bigger and thereby even more easy to find !???
Somehow I have difficulties seeing the rationale behind it...

[Mr Optimistic]

Does seem odd that you have a nice big brightly painted orange box to help location, and then accept that the memory may depart company over differing 'inertias'. Still, presume its a standard design and there must be a reason. On the pressure issue, way I looked at it was if you put the sand in an isostatic press and applied pressure from all sides you would expect the grains to lock. Still, I have been wrong before !

[henra]

Looking at the deformed orange box I was wondering how it is exactly installed in the A330 (where exactly and in which orientation) and if we can derive something from the damage pattern about direction of forces applied.

Have we touched that somewhere and I have simply overseen/forgot it ?

[sensor_validation]

Dumb insensitive British press at its worst

Robot submarines find part of Air France jet black box 13,000ft under Atlantic | Mail Online (http://www.dailymail.co.uk/news/article-1381434/Robot-submarines-Air-France-jet-black-box-13-000ft-Atlantic.html?ITO=1490)

[edit]Report now updated to refer to bodies of "passengers" and not "survivors"

[AlphaZuluRomeo]

If the "beer can" is much denser than the chassis, they should look back to the East of the Chassis location to have a hope of finding it.
:=
You're assuming the crash site (impact with surface) being east of the wreckage... LKP being east doesn't mean -IMO- that the plane impacted water on the same side... Therefore, the memory "can beer" may lie everywhere around.

[iakobos]

@JD-EE

I fail to see a loop.

It looks very much like a small (semi) vertical monopole planted on the virtual ground (the aircraft).
At about 9 feet its resonance is around 26 MHz, (radiation) efficiency of the order of 1%, a set up similar to an HF whip on a car.
The location allows for a rail-kind of radiator, it helps to handle the many Amperes (not far from 100 ?) and flattens the bandwidth behavior (no need to retune when staying within a same frequency band).
Radiation would be pretty well omnidirectional with a peak towards the front (more return current).

Worth a different thread perhaps.

Kalimera

[captplaystation]

sensor validation,
I am no fan of the "hero pilot steers stricken plane away from school" style of reporting we often see, but I have looked at the article you linked to and cannot find an explanation for the reasonably factual content it contained deserving such lambasting, am I missing something ?

[Centrosphere]

Dear sirs,

I definitely don´t identify with the conspiratory fringe. But I find the image of the box found at the bottom strange.

Just have a look, in the original image, at the region I have marked here.

http://i.imgur.com/2T1rH.jpg

If you amplify that region with Paint, you´ll see that the texture of the pixels are different from the rest of the image. It seems to me like someone tinkered with the image.

http://i.imgur.com/l78pV.jpg

But I really can´t think about a reason for that.

Also, if it really is an altered image, this could be the reason why BEA decided to distribute the photo popping up from the monitor (as someone observed sooner). Looking at the monitor conveys the feeling that we are witnessing the real workings of the ROV, not that we are really looking to an altered image.

[snowfalcon2]

From pictures of DFDRs I find it remarkable that the pinger's (ULB) attachment to the memory unit (CSMU) in the Honeywell SSDFDR seems to be a rather lightweight affair. (The ULB is the smaller "can" affixed to the end of the memory unit.)

FAA regulations prescribe that the ULB shall be "securely attached" to the memory module, which is quite logical.

Each recorder container must:
(1) Be either bright orange or bright yellow;
(2) Have reflective tape affixed to its external surface to facilitate its location under water; and
(3) Have an underwater locating device, when required by the operating rules of this chapter, on or
adjacent to the container, which is secured in such a manner, that they are not likely to be
separated during crash impact.

Looking at the debris in this case I would not be surprised if the ULB has separated from the memory unit. That will probably not affect the chances of finding the memory unit now, but it may have contributed to the failure of the initial search operations.

[cura]

"Also, if it really is an altered image, this could be the reason why BEA decided to distribute the photo popping up from the monitor (as someone observed sooner). Looking at the monitor conveys the feeling that we are witnessing the real workings of the ROV, not that we are really looking to an altered image."

If i thought that i was watching live imagery from the ROV then i would expect to see at least depth, heading and speed info on the screen.

[Centrosphere]

Catplaystation,

I think "sensor validation" was shacked by this phrase:

"The latest retrieval operation started after cameras pinpointed wreckage and the bodies of survivors some 4000 metres (13,000 feet) down."

"Bodies of survivors" don´t seems a sensible description of what the expedition found at the bottom...

[snowfalcon2]

I definitely don´t identify with the conspiratory fringe. But I find the image of the box found at the bottom strange.

Just have a look, in the original image, at the region I have marked here. If you amplify that region with Paint, you´ll see that the texture of the pixels are different from the rest of the image. It seems to me like someone tinkered with the image.

But I really can´t think about a reason for that.

To me it looks like the area you point out is the middle of the picture. It also appears to be (quite logically) the area where the two main searchlight beams converge. This implies that all shadow areas "vanish" in that particular area of the picture, making the surface features appear very low contrast and featureless.
Towards the sides of the picture the shadows appear different as you can see the sharp shadows from each individual searchlight beam. The twin beams also make the shadow of the DFDR chassis look rather odd.

A somewhat similar optical effect appears when you look from your airplane exactly down-sun i.e. towards the airplane shadow. The shadow is surrounded by a light "halo" with very low contrast.