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AF 447 Search to resume

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AF 447 Search to resume

Old 25th Feb 2010, 00:15
  #301 (permalink)  
 
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Originally Posted by mm43 View Post
With regard to the V/S, the following translated comment was made:-
[...]
The "flew away to the front" is something the BEA have never mentioned.
This was in the first report (at least). To quote the section on the VS (my emphasis added):
The middle and rear fasteners with the related fragments of
the fuselage hoop frames were present in the fin base. The distortions of the
frames showed that they broke during a forward motion with a slight twisting
component towards the left.
By the time you've gone via french, german and english, "flew away to the front" is about right.
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Old 25th Feb 2010, 00:25
  #302 (permalink)  
 
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Kevin Smith

On 9th November you suggested active life of recorders on seabed could be extended by not transmitting active accoustic signals until active searching was observed. The degree of extension depends on ratio of "listening" power drain to "speaking" power drain.I have no idea of this.
An alternative could be to eject recorders(with flotation device) when outside pressure corresponded to few feet of water. Problem would be demonstrating lack of "nuisance" events. You might like to consult with manufacturers of recorder packages.
Keith
As an electrical engineer familiar with transmit vs receive power consumption of various devices I can tell you that transmit power consumption is at least an order of magnitude greater than receive power consumption. That having been said, the low duty cycle of the pingers mean that even when they are active they are only consuming large amounts of power during the "ping" itself. The net effect could be that battery life would not be appreciably extended by putting the device into a listening only mode.
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Old 25th Feb 2010, 00:33
  #303 (permalink)  
bearfoil
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infrequentflyer789

I may be a titch too picky and/or pedantic, but for me the documents reek of "guided perception". In an accident with precious little conclusive evidence, I'll hang on to my opinion of a precipitous and less than objective initial report. "In Line of flight" is a charged and loaded phrase, unpredictable when read by lay people, and suspiciously incorrect based on examination of the wreckage when considered by a pilot (imo). Who can know the a/c was "lined up with airflow" into the wind when it impacted. It conveniently suggests that at whatever rate it was traveling horizontally, there was no component of skid, or slip. Neither would anyone think the airframe was "rotating about its architectural center point", ie, "spin". It imputes to an a/c that has just fallen from seven miles an exaggerated amd beneficial explanation that also suggests it had flyable characteristics remaining. And even if it did, no evidence exists to defend the a/c by concluding "Intact at impact". It cannot have yawed into the Sea such that the VS spun off the fuselage, and have hit "En Ligne de Vol". I wouldn't expect a harsh report either, but to me, it appeared defensive of the a/c, and less than objective. Followed by AF CEO claiming the pilots were "unlucky" to have "missed" a radar report that "all other pilots in the vicinity saw", initially blaming lightning (!), and then weather (we don't know that still), the pilots have no one to defend them.

The rapid dissemination of the first report and BEA, AF and AB with their many press conferences established a climate of guilt. Who is guilty? Anyone but AF? AB? Why focus on the impact results and avoid the cause of upset? Very careful with the cause, heavy on the result; slanted, imo.

bear
 
Old 25th Feb 2010, 00:44
  #304 (permalink)  
 
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infrequentflyer789
By the time you've gone via french, german and english, "flew away to the front" is about right.
Good one. It seems that they have fiddled with language used in both reports, but essentially the aircraft had some forward moment and at the time of impact had either the tail yawing to port, or was rotating in a horizontal plane in a clockwise direction. I'm sure they've calculated the numbers on both.

mm43
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Old 25th Feb 2010, 01:32
  #305 (permalink)  
 
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What the aircraft was doing must be taken in context with what the pilots were doing at the time,

Too early to decipher initial reports for the layperson. When all the majority of lay readers really want to know is what caused the accident and little care or comprehend how it happened.
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Old 25th Feb 2010, 01:47
  #306 (permalink)  
 
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Nonsense

Uncle Jay, how do you relay plane to plane on a route that has one plane a day and is well away from any other routes that might have planes?

This has been brought up here before with actual routes cited. Yet people keep harping on this idea who have not reviewed it in detail. How much volume of traffic will be handled through what communications channels plane to plane over what routes?

Volume of traffic is a chronic stumbling block I see in this group. One is easy therefore infinity is easy, too. 'Tain't so McGee.

{^_^}
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Old 25th Feb 2010, 01:57
  #307 (permalink)  
 
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Sallyanne, keeping streams separated and communicating through satellites is a done deal. Back in the 80s it was a done deal on the DSCS satellites and ground stations. As you say, it requires a proper protocol. It's been invented already, several times. Inmarsat M is another protocol which manages this.

Privacy is a minor problem. If you data that is converted to a stream of bits then encrypting it to send and decrypting it on receipt is no big deal. Every time your browser shows the little lock that's being done for you on the Internet.

Volume is a problem. And price is a problem. And spectrum is a problem.

How much data do you want to send? Maybe spectrum that is being abandoned at HF as HF broadcasting becomes a lost art could be recycled if the data streams are small enough. Perhaps you can send deviation from flight plan rather than actual position.

Volume of data and limited spectrum availability drive price. Do we put airlines out of business simply to send data that statistically is not needed? Sending a megabyte of data for every byte that is actually needed and used seems to me to be pointless.
So how much is that one byte worth? Can it be reasonably amortized over the entire data volume being proposed?

{^_^}
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Old 25th Feb 2010, 03:30
  #308 (permalink)  
 
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Once again, as if it was a "fait accompli" the SPIEGEL ONLINE delivers the same rhetoric : The pilots flew straight into the deadly cloud. Period.
Der SPIEGEL goes as far as producing the explanation for that : Pilots are so Company minded that they don’t want to burn the extra fuel for a weather deviation and risk a fuel stop later on.

Herr Traufetter, can I say you have been ill advised on that one ?

But the following looks very tasty …
Early next month the German BFU will publish an unpleasant investigation report for Airbus on the near-crash of a Lufthansa A320 in Hamburg two years ago. An unexpected reaction of the flight computer caused the left wing of the jet drag on the runway. The BFU will make a total of twelve safety recommendations, including the Airbus computer programs.
Can hardly wait ...

Thanks for the article mm43.
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Old 25th Feb 2010, 03:37
  #309 (permalink)  
 
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Composite aircraft vs aluminum aircraft

AF447 had an unusual amount of composite materials aboard. The portions of the plane that contained the FDR and CVR were very heavily composite.

We know how aluminum, even shredded aluminum, sinks fairly well. Does anybody have any idea how a shredded AF447 might have sunk? How long would it take to reach the bottom if, say, the tail cone came off almost as a single piece? How would that affect the size of the debris field?

Fortunately the engines are likely to be "straight on down" items. So I expect them to be found. Then they have to determine how the debris field is spread out and locate the recorders within that field.

I wonder how difficult that effort will be. I also wonder if it would be a good idea to somehow attach recorders to engines rather than parts of the plane that may have close to zero buoyancy. It might increase their chance of being found in the rare crashes like AF447 over really deep water.

{^_^}
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Old 25th Feb 2010, 11:28
  #310 (permalink)  
 
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Sallyanne, keeping streams separated and communicating through satellites is a done deal. Back in the 80s it was a done deal on the DSCS satellites and ground stations. As you say, it requires a proper protocol. It's been invented already, several times. Inmarsat M is another protocol which manages this.
Existing systems cannot provide this requirement which is for continuous, fast and reliable data simultaneously from hundreds of aircraft moving at high speed. Ask any provider for a quotation!

Volume is a problem. And price is a problem. And spectrum is a problem.
Yes, as has been said ad nauseam. No-one has said this can't be done. Only that it is not an economic proposition.
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Old 25th Feb 2010, 12:33
  #311 (permalink)  
 
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Exactly right, it isn't economic for whole fleets, or even whole long haul fleets, to be continually transmitting data to satellites.

There is, though, a case for aircraft in areas of consistently poor communication with ground voice stations and HFDL facilities, on thinly travelled routes, having the capability to transmit out of the norm data and the transmitters having enough stored power to continue to transmit at least position once/if the aircraft's own electricity supply fails.

Examples would be, over water:
the South Atlantic, portions of the South Pacific and the southern Indian Ocean and
overland:
portions of the Arctic, parts of Saharan and sub Saharan Africa and parts of Asia in the CIS/Mongolia/China region.
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Old 25th Feb 2010, 14:43
  #312 (permalink)  
 
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Why don't aircraft carry EPIRBs similar to ships?

EPIRBs are required equipment for ships at sea and I wonder why a similar device is not carried by aircraft. Emergency position indicating radiobeacons (EPIRBs), devices which cost from $200 to about $1500, are designed to save your life if you get into trouble by alerting rescue authorities and indicating your location. Category I406/121.5 MHZ. Float-free, automatically activated EPIRB. Detectable by satellite anywhere in the world. Recognized by GMDSS.rlime
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Old 25th Feb 2010, 15:36
  #313 (permalink)  
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the engines are likely to be "straight on down" items.

You're assuming they were still attached to the wings on entry. Probably not true.
 
Old 25th Feb 2010, 15:39
  #314 (permalink)  
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Aha! Uncle Jay has some crash analysis information to share? Probably not true.
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Old 25th Feb 2010, 16:11
  #315 (permalink)  
 
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Aha! Uncle Jay has some crash analysis information to share? Probably not true.
However I agree that he is probably correct.
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Old 25th Feb 2010, 17:48
  #316 (permalink)  
 
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Aha! Uncle Jay has some crash analysis information to share? Probably not true.
However I agree that he is probably correct.
Oh for goodness sake! Based on WHAT exactly???

Honestly, if they hadn't found the VS floating around in the ocean how many would have pontificated that it would have sheared off... none is my bet.

Rumors are one thing, conjecture extrapolated from the limited information we have another, but the good ol' WAG doesn't add a single thing to this discussion.

- GY
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Old 25th Feb 2010, 18:52
  #317 (permalink)  
 
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Rumors are one thing, conjecture extrapolated from the limited information we have another, but the good ol' WAG doesn't add a single thing to this discussion.
I can assure you I don't make WAG's

But based on the tone of your post I will not answer it further
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Old 25th Feb 2010, 19:01
  #318 (permalink)  
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And yet if it hadn't been found floating by itself, but attached to additional wreckage, shearing off could be eliminated. Eliminating possibilities is one way to distill a solution. Eliminating possibilities that present themselves and cannot be reasonably eliminated means a closed opportunity that could be pursued. The most open-minded scientists I know are Pathologists. Claiming someone's opinions are not useful without the evidence to claim it falls likewise into the realm of rumor, Speculation, and other hindrances.

587. a/s less than 250 knots. Encounters wake turbulence. Three yaw cycles later the VS/Rudder leave the airframe. Falling 2,000 feet, both engines are slung off the wings before one spin is completed. Without engines and tail feathers, this 300 series Airbus has accomplished in fifteen seconds what 447 was given four minutes to do, from seven miles up starting with an airspeed twice that of 587.

"The aircraft impacted the water intact". Could happen.

bear
 
Old 25th Feb 2010, 19:18
  #319 (permalink)  
 
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rlime
Why don't aircraft carry EPIRBs similar to ships?
The Flight Data Recovery Working Groups Final Report at:-

http://www.bea.aero/en/enquetes/flight.af.447/flight.data.recovery.working.group.final.report.pdf

examined the practicality of new/retrofitting GELT (equivalent GEPIRB) and their conclusions are noted on page 20, clause 3.4 under Deployable ELTs with GPS position broadcasting. The following scores out of 10 (highest) were recorded by the group for this proposal:-

Technical Maturity = 9. The technology is mature. Fully qualified military system exists today and the path to civilian certification is easy. FAA TSOs are in place to support.

Equipage (Aircraft/Ground) = 6. New equipment would be needed on the aircraft, but the feasibility is proven on helicopters for over 30 years.

Cost = 1. The cost per aircraft exceeds $10K. Would only replace one existing ELT. The 2 ED-112 recorders would still have to be installed. The cost to design an aircraft-specific tray “only” for an ELT is not justified, since in that same tray a deployable recorder with ELT could be installed.

Applicability = 6. As it provides an immediate incident alert and notification of a downed aircraft, it increases the probability for wreckage localization and data recovery. The data recoverability is null. The contribution to localization was computed using the formula mentioned earlier (see link above).

Global Score = 4.45.

It is on the "to do" list, but implementation could be a way off.

mm43
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Old 25th Feb 2010, 19:58
  #320 (permalink)  
 
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I am sure this has been discussed, but why can't aircraft on routes over the ocean transmit their FDR data to one another for storage? One of the planes down, the other makes it to land and the data gets downloaded. VHF traffic costs nothing, and so does storage.
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