Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF 447 Search to resume (part2)

Tech Log The very best in practical technical discussion on the web

AF 447 Search to resume (part2)

Old 9th May 2011, 16:56
  #1001 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Back to the Facts

Hi,

Browsing again the old BEA reports, I found this quote which should have been taken into consideration much earlier by most of us as for the initial state of the recovered floating bodies, next, enlightnig someway the nuisance of the various rumors circulating from "tabloids" reporting sources:
Originally Posted by BEA first interim report, page 40
1.13 Medical and Pathological Information
Sailors from the Frigate Ventôse recovered about thirty bodies. A visual examination of the bodies showed that they were clothed and relatively well preserved. All of them were handed over to the Brazilian Navy to be transferred to the Recife morgue.
This would contradict most of the press releases (still today summaries):
1. Many bodies were recovered by the French Navy (about 3/5th by Ventôse);
2. They were clothed and well preserved;

S~
Olivier
takata is offline  
Old 9th May 2011, 17:01
  #1002 (permalink)  
 
Join Date: Jun 2009
Location: France
Age: 78
Posts: 41
News from BEA

Information, 9 May 2011

They have recovered one engine and the avionics bay.
milsabords is offline  
Old 9th May 2011, 17:14
  #1003 (permalink)  
 
Join Date: Jul 2007
Location: My Stringy Brane
Posts: 379
Some BEA photo isolations from today's briefing:





An A330 avionics rack (hat tip to PJ2):




AF447's rack being hoisted aboard:




Recovered rack components:

Machaca is offline  
Old 9th May 2011, 17:19
  #1004 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 72
Posts: 2,410
Machaca;

Many thanks once again.

With the Avionics Bay comes the memory boards/chips of the FCPCs, FCSCs and possibly the QAR. If a card, (and I now suspect it is), it may be readable if not shattered. The card is placed in a slot so is somewhat "protected" unless the unit itself was crushed. What we see of condition of the boxes is encouraging. Let us hope for the best here as well.

I see from the photograph of the engine that half the stator-blade section is missing, confirming what was seen in the original photographs.
PJ2 is offline  
Old 9th May 2011, 17:33
  #1005 (permalink)  
 
Join Date: Jun 2009
Location: France
Age: 72
Posts: 193
auv-ee:
Thank you for pointing me to your previous very interesting post on the subject.

Can we assume that a 20db signal to noise ratio is about the detection capability of TPLs ?

Since we are in the ITCZ intermittent heavy showers have a significant probability of occurring at any time. I read in a US Navy paper that rain drops impacting sea surface and implosion of air bubbles caused by rain produce noise in the 1-100 kHz band with max SL @ 20 kHz and SL can be up to 30 dB above sea surface noise though I think the intensity is lower at great depths. It seems that if the TPLs were flown at, say 1700 m from the nearest pinger a simple shower occurring at the same time would have prevented detection. As I understand phase I, any area was swept only once so perhaps the failure was only bad luck.

OTOH, it is very possible that both ULB failed in the crash.
DJ77 is offline  
Old 9th May 2011, 17:55
  #1006 (permalink)  
 
Join Date: May 2010
Location: MA, USA
Posts: 126
Originally Posted by DJ77
Can we assume that a 20db signal to noise ratio is about the detection capability of TPLs ?
If they were using a traditional detector, which consists of a narrow-band filter, a peak detector and a threshold comparison, then 20db would be about right. If they are doing more modern signal processing, then it might be considerably better (another 10-15db, perhaps).

Since we are in the ITCZ intermittent heavy showers have a significant probability of occurring at any time. I read in a US Navy paper that rain drops impacting sea surface and implosion of air bubbles caused by rain produce noise in the 1-100 kHz band with max SL @ 20 kHz and SL can be up to 30 dB above sea surface noise though I think the intensity is lower at great depths.
Those numbers sound about right. I expect that the 30db increase is compared with sea state 0; the increase will be comparatively less if the surface already has breaking waves. Also, these high frequencies are attenuated with distance, as I noted in the earlier post; so, yes, the effect will be less at depth. Also, at 4000m depth, the rain noise is being averaged from a similar radius area of the sea surface; thus a rain shower that does not cover that whole area of the sea surface, will have a lower total effect.
auv-ee is offline  
Old 9th May 2011, 18:09
  #1007 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 873
Weak signals detection

If the half buried SSCVR ULB was transmitting as specified the chances to be detected with available techniques and adequate methodology were very high.

I am very familiar with "weak signals detection" using DSP techniques, intrinsically quite insensitive to noise.

In the picture below:



You have a signal that could be IMPOSSIBLE to be heard and with proper techniques can be CLEARLY detectable in the computer screen (High Signal to Noise ratio) using widely available FREE software PC (Win) compatible.

For example:

With this setup you could tune in a distant NDB (impossible to be heard, even it´s carrier) and it will come up "loud" and CLEAR in your screen

Another example:

You could have a CW 10W HF carrier operating in the 5 MHz* aeronautical band (dark hours) in the a/c, being monitored in DKR or REC with near 100% chances to tell you when disappear triggering an alert.

(*) 8 MHz in daylight.

Even with the current HF antennas (a/c and ground stations) very poor compared to the ones used by dedicated amateur radio in their stations.

PS

I will investigate what kind of Receiver they used in order to understand on their capability to succeed in cases like AF447.

And if the wreckage did fall in a hilly region it would be more difficult.
RR_NDB is offline  
Old 9th May 2011, 18:12
  #1008 (permalink)  
 
Join Date: Feb 1999
Location: UK
Posts: 1,078
I recall from the NASA Columbia investigation that bodies recovered from in-flight breakups, or from the failure of a pressure vessel at a significant height, the bodies in all previous recoveries were denuded; this was the case in Air India 182 and Pan Am 103.

The fact that bodies from the AF447 are fully clothed, I assume, rules out any in-flight breakup and explosive decompression?
no sponsor is offline  
Old 9th May 2011, 18:17
  #1009 (permalink)  
 
Join Date: Aug 2009
Location: Texas
Age: 60
Posts: 5,361
From the PDF
The end result of two years work is a training package including a video and a CD-ROM, giving an airplane upset recovery training aid.
However, all members of the joint industry group agreed that the package is aimed at preventing loss of control accidents on conventional aircraft. It is not aimed at protected Fly-by-Wire aircraft. There is no need for this type of continuation training on protected aircraft, although a general knowledge of the principles involved is useful for every pilot.
One hopes that this apparent hubris has been mitigated in the interim. (Report is 15 years old, yes?) I say this fully acknowledging that the author is a better pilot than I.
We wanted a general knowledge based approach, as opposed to a rule based one. For this, after proposing some initial actions, we talk about “additional techniques which may be tried”. This obviously is more difficult to teach
The difference between education and training. I applaud the approach advocated.
When we started our discussions, the training being given in the airlines to recover from excessive nose-up pitch attitudes emphasised rolling rapidly towards 90° of bank.
A boilerplate "unusual attitudes" recovery technique.
Based on our experience as test pilots we are very wary of using rudder close to the stall. It is the best way to provoke a loss of control if not used very carefully, particularly with flaps out.
As discussed previously in various AF 447 posts ... and as seen in stall training in small single engine trainers.
JD-EE
If you are going to design an aircraft that gives up control when the automation gets confused but not before then you need the pilots to have the most wide open control possible. Maybe that will be a takeaway from AF-447.
If your suggestion is to be considered, there is likely a cultural (industry and/or corporate) issue that may be non-trivial to address .
Meantime, lobby for a switch on the radar front panel that may involve an "ARE YOU REALLY SURE?" interaction with the pilot that enables full control of the display including any raw mode that could exist. The pilots are being offloaded for other flight controls. So they have time to operate the radar in detail modes; and, they have time to learn how.
I think you mean "for other flight duties" but I see what you are headed towards.

I learned radar work on a scope with more or less raw video (ship board radar) and was disappointed in later graduating to the APS-124, which only providing processed video to my cockpit display in the (then new) SH-60B. One factor that drove this choice was that the data from the radar had to be in a form that would easily go down a directional data link to the ship's Combat Information Center. That tech and design decision allowed the radar to share space in the cockpit with our other tactical displays, via a selection toggle, but it constrained how much one could get out of the radar itself. It also allowed either the pilot, or the crewman, to work the radar.

While I share your position on giving the pilot the choices to tweak the display and input, there is the design problem of competing with other capability for real estate in the finite amount of space provided for pilot attention on any flight deck.

Ergonomics at its most interesting.

Some of the folks who operate that radar have, in various posts over the past two years, pointed out that there is some room to "tweak" the display during a given trip. It may be "good enough" with enough operator training, habit, and familiarity. This points again to a cultural issue, possibly moreso than a design issue.
Lonewolf_50 is offline  
Old 9th May 2011, 18:18
  #1010 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 873
QAR media

What we see of condition of the boxes is encouraging
(#1003)

Surprisingly in better condition than i first thought. Considering the bay location in the a/c.

Last edited by RR_NDB; 9th May 2011 at 18:44. Reason: Comm. impvmt.
RR_NDB is offline  
Old 9th May 2011, 18:34
  #1011 (permalink)  
 
Join Date: Jun 2009
Location: Germany
Age: 66
Posts: 782
zoom-boom scenario

I´m somewhat astonished concerning this scenario.
Flying at FL 350 with a still heavy aircraft, how much climb could be produced even with full power? Is there enough elevator authority available to get the climb rate going to reach such an AOA and how fast would airspeed degrade? Gums with his F16 could have done it, my F4 would just have produced a lot of drag on such an elevator input and would have picked up a descent rate instead of a climb rate.

Next question is, at what point of the events and with what kind of airspeed could this pitchup have started? Icing of pitots, therefore unreliable airspeed (not known to the crew jet), turbulence and autothrust of, stall onset at the low speed region (not clearly identified by the crew yet, might be mixed up with turbulence issues). Crew-action increase thrust leading to pitchup (underslung engines, unfavorable CG), with slowing down descent rate, but not curing the pitch problem (correct speed still not known to the crew, work overload, turbulence.....). Nose stays up crew reduces thrust again..........

At what forward speed would we define the upset (if it happened) from FL 350 to FL100 and then on down to the water? If the normal flying speed is 470 KTAS in FL 350, is the thing still flying with 300 KTAS? Per my definition the aircraft would be out of flying speed way before the previous mentioned 60 KIAS from other posters.

The going down in a upset condition would probably never be in a straight line, struggling with a falling aircraft in free airspace directional control would be my last worries. It might have done one or more turning/ yawing motions around the vertical axis, it is at least more probable in an upset than a straight line. That sums up for the missing time. And it might not have been a continuous upset, secondary stalls are quite a common encounter in well controlled training environment (planned, briefed, prepared and good weather).

I´m not saying, that´s what it was.

franzl
RetiredF4 is offline  
Old 9th May 2011, 18:36
  #1012 (permalink)  
 
Join Date: Jan 2008
Location: uk
Posts: 780
Originally Posted by jcjeant View Post
Hi,

I don't agree with this supposition ... if you read the ACARS ..
BEA read also the ACARS ... and maybe more we don't know about.
I can't suppose a glide from them.
But if you keep an open mind, there is a small possibility of such - similar to the small possibility of both pingers failing (maybe about 1%). Looking at the ACARS, I too would have assumed no glide, but I would also have assumed at least one working pinger based on track record.

The aera phase 1 the very first research .. (with ASSUMPTION of working pingers) was not a large one !
Really ? They failed to completely search it all (hence the phase two) within the pinger specification time despite using two TPLs, a nuclear sub, several surface ships and another sub + a ROV. What would you consider a "large" search area, and how much resource would you need to deploy to search it within the 30days ?

And phase 4 included the crash site.
The difference is they used appropriate tools for this search and they assumed (this time) that the pingers were no more working !
No, they did not "assume", given the lifetime (30days minimum, 40 expected) the pingers are known to be no longer working by this stage.

At the first search .. they have two doors to open ....
One with the pingers in the room .. the other with no pingers ...
They opened only one door .
First search - pingers over 90% probability of working, larger area can be covered faster by looking for signals. Later searches - pingers <1% probability of still being working, so use other slower search methods over smaller area. Eventually got lucky.

It's easy to use hindsight to say they should have bet on the 100:1 outsider after you know the result.
infrequentflyer789 is offline  
Old 9th May 2011, 19:01
  #1013 (permalink)  
 
Join Date: Mar 2001
Location: us
Posts: 694
From Tim Vasquez's excellent meteorology of nearly two years ago.





IMO, the possibility of a downdraft beneath the anvil contributing to the rate of descent ought to be considered.

Vasquez's site for his AF447 work.
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data
SaturnV is offline  
Old 9th May 2011, 19:17
  #1014 (permalink)  
 
Join Date: Jul 2009
Location: UK
Posts: 133
Originally Posted by SaturnV View Post
IMO, the possibility of a downdraft beneath the anvil contributing to the rate of descent ought to be considered.

Vasquez's site for his AF447 work.
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data
Watch out Tim's work was produced very early on when it was assumed the Brazilian navy had a location for the final ACARS message - which later turned out to only be extrapolated, and now some 30NM off. I think this moves the final transmission right into the heart of that Cb.
sensor_validation is offline  
Old 9th May 2011, 19:17
  #1015 (permalink)  
 
Join Date: Feb 2001
Location: right here inside my head
Age: 60
Posts: 178
That's a terrific picture of the engine! You can see the 12 o'clock position facing the camera --their sling is hanging it from it's 9:00 -- and the fwd eng mount quite well... [*edit*Clearly*] it appears** the bottom forward half of the engine took the brunt, pulling the forward mount down, shearing those mount bolts and pushing the aft upper portion of the engine upward... Can't see what failed there, because the aft mount is gone.

Last edited by 3holelover; 9th May 2011 at 19:33.
3holelover is offline  
Old 9th May 2011, 19:47
  #1016 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 77
Posts: 1,458
RR_NDB
You have a signal that could be IMPOSSIBLE to be heard and with proper techniques can be CLEARLY detectable in the computer screen (High Signal to Noise ratio) using widely available FREE software PC (Win) compatible.
I believe the technique you are referring to is a phase lock loop system.
Phase-locked loop - Wikipedia, the free encyclopedia
Real electronic black magic. No doubt the EE folk will have more to say.
Machinbird is offline  
Old 9th May 2011, 20:02
  #1017 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 66
Posts: 1,202
or in my day lock-in amplifier
Mr Optimistic is offline  
Old 9th May 2011, 20:10
  #1018 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 63
Posts: 1,809
Cool

Hi,

That's a terrific picture of the engine!
Sorry for the big size (so I post only the URL) .. but this give a better view (engine) of what explained above ... (magnified 150 % of the original BEA pic)

http://i.imgur.com/F0cQX.jpg
jcjeant is offline  
Old 9th May 2011, 20:20
  #1019 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 873
Digital Signal Processing

Machinbird,

Real electronic black magic
PLL is just a "building block" that can be "hardware based". And are powerful.

DSP systems are IMPRESSIVE. You use the "computing power" to "remove" the noise (that is ramdom) to detect the signal (that is coherent) using Redundancy.

The results i observed are simply unbelievable. So i designed a "Propagation Tester" using it that can be understood in my PY2CW mobile Ham Station website.

Using the synergy between HF and Internet in "near real time".

I am curious to known what kind of Receiving Technique they used in the failed ULB location.

Last edited by Jetdriver; 10th May 2011 at 03:55.
RR_NDB is offline  
Old 9th May 2011, 20:36
  #1020 (permalink)  

Dog Tired
 
Join Date: Oct 2001
Location: uk
Posts: 1,661
It's all very well for you experts to pontificate about the several sciences involved but I am simply amazed that they have got an engine up from that depth.

I know how big that engine is and I applaud their efforts.
fantom is online now  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.