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-   -   AF 447 Search to resume (part2) (https://www.pprune.org/tech-log/449639-af-447-search-resume-part2.html)

grizzled 24th Apr 2011 15:15

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 24th Apr 2011 16:06

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 24th Apr 2011 16:44

No turbulence
 
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 24th Apr 2011 17:12


Originally Posted by CONF iture (Post 6409583)
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 24th Apr 2011 17:21

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 24th Apr 2011 17:33


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 24th Apr 2011 18:24

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 24th Apr 2011 18:35

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 24th Apr 2011 18:39

Weather Radar
 
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 24th Apr 2011 18:55

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 24th Apr 2011 19:02

K.I.S.S. x K.I.C.S.
 
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 itīs implementation.

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

Letīs imagine the scenario of:

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

Whtīs lacking in this analysis?

henra 24th Apr 2011 19:09


Originally Posted by DingerX (Post 6409827)
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 24th Apr 2011 19:24


Originally Posted by RR_NDB (Post 6409950)
1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
3) Had pitotīs 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 24th Apr 2011 19:39

Pitot Probability
 
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 24th Apr 2011 19:51

Ok, letīs look at each point:

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
3) Had pitotīs 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 msgīs
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 24th Apr 2011 19:53


Originally Posted by DozyWannabe
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.



Originally Posted by GerardC
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 24th Apr 2011 20:02

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 24th Apr 2011 21:27

Wx Radar Factor
 
RR_NDB

Ok, letīs 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 24th Apr 2011 22:12

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 24th Apr 2011 23:40

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.


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