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AF 447 Search to resume

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AF 447 Search to resume

Old 23rd Apr 2011, 19:20
  #3881 (permalink)  
 
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Nigel, there is a mode of communications used by ham radio operators that sends a puny 31.5 bits per second of data. You can fit 25 to 50 of them into one HF speech frequency allocation. And you can drag out 100% copy from signals you cannot hear with your ears in a normal SSB radio. (I have used it in the past to communicate with places like South Africa, Chile, and Europe from Southern California well after the 14 MHz ham band was close tighter than a drum for most other modes of communications.) I'd not worry about "too slow" as 63 bits per second and 128 bits per second variants exist. The latter would cut you down to 6 to 12 sub-channels per channel. An unencoded ACARS message would go through several times in 10 seconds or so on one subchannel. If planes are assigned "time slots" accommodating large numbers of planes would not be hard.

Now, to what benefit. It's not going to STOP a crash. It only tells you within 80 miles or so where the plane stopped transmitting. That's a LARGE area to search. So you've not bought much even for the postmortem search effort. And if the search area is socked in, as in this case, you still must patiently wait until you can get calm enough water that mostly submerged objects stand out to you when searching a thousand square miles or so.

(And the first time a massive search effort is triggered by a part in an ACARS radio gasping its last breath and shutting the radio down at the same time DAKAR is being derelict, again, the whole thing will be shut down.)

It might be more salubrious to lean on outfits like DAKAR and to a lesser extent ATLANTICO to invest a few more brain cells in their day to day operations.
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Old 23rd Apr 2011, 19:21
  #3882 (permalink)  
 
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Thanks Svarin: at least I read all the text

So let me get this straight: the pilots are awake and paying attention in the period 2:01 to 2:10. The air speed data becomes unreliable, the a/p and auto throttles kick out the crew manage the aircraft and get to a state were re-engagement of the a/p is a possibility in their minds, they then re-engage it, the system coughs up a fault message but even after the exciting preceding episode, they allow the air speed data and automatics betray them again ?
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Old 23rd Apr 2011, 19:24
  #3883 (permalink)  
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Originally Posted by JD
Does this change your assessment?
- no. It is his ship (no sick humour intended).
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Old 23rd Apr 2011, 19:26
  #3884 (permalink)  
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Mr.O

Well, it looks that way, but Airbus pilots are proud and dependent upon an almost universally safe a/c in the A330. It would not be unusual to defer to a/p once things had gotten 'safe' again.

Per the AD, and Savarin, when re-selected after UAS the a/p is known to command extraneous and dangerous Pitch excursions. Likely in this case to have instigated an unrecoverable upset, via Stall, overspeed, or Roll +.

sorry for barging in, I think Svarin has left the building,
 
Old 23rd Apr 2011, 19:30
  #3885 (permalink)  
 
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Yes that is what I thought was meant. But in this theory isn't there a Phase 1 which did something similar, so now you give the system a second chance to beat you ? Wouldn't you be some what cautious after the fright of your life caused by unreliable airspeed ? Seems to demand a degree of stubborn tenaciousness.
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Old 23rd Apr 2011, 19:38
  #3886 (permalink)  
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I tend to think there was very little fear in the cockpit, even with UAS at hand. You ask good questions, but my Faith and Trust remains with the Pilots, it will take more than a report from BEA to convince me that these gents boffed the poodle in any way.

Now, Upset??? GOD would shit his drawers.....
 
Old 23rd Apr 2011, 19:41
  #3887 (permalink)  
 
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Ok, we'll see. Of course it would also shrink the timeline re height loss.
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Old 23rd Apr 2011, 19:45
  #3888 (permalink)  
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ptf "pardon the french". I seldom use profanity, but sometimes due lack of better vocabulary......

RE: Timeline. How so??
 
Old 23rd Apr 2011, 19:47
  #3889 (permalink)  
 
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bearfoil nailed it

quote "Did all Tx (ACARS) arrivee via FIN?? Or was the last one, the Cabin Speed, tx by the Fuselage, after the famous gap in ACARS, the loss of the Fin causing the Bus to switch to SATCOM?? If so, that explains the gap in tx, and would explain the possible loss of the Fin at altitude, coinciding with a depressurization, a hull rupture, and the possible loss of some cabin contents, explaining the lack of damage to the Galley structure, when the recovered cabin liner right next to it was utterly destroyed."

That's the sequence that has been bugging me since the beginning. That galley floating relatively undamaged seemed to tell a tale of a back-broken airplane spitting parts. BTW what exactly does UAS mean?
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Old 23rd Apr 2011, 19:49
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Its how the dsylexic spell America. PTF, oh silly me. If Pt1 didn't lose the height, Pt 2 lost the height in less time. Yes I know its an assumption re Pt1 ! My assumption is Unreliable Air Speed.
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Old 23rd Apr 2011, 19:52
  #3891 (permalink)  
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I'm in need of some clarification myself. What is Pt1/2.

I have been segregating different regimes of flight to sort what little evidence there is available, for instance, at some point, Flight Path morphed into 'Trajectory', (Trajectories).
 
Old 23rd Apr 2011, 19:56
  #3892 (permalink)  
 
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That's got to be pitot 1 and 2, not?
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Old 23rd Apr 2011, 19:56
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Sorry. It was Svarin's post. He makes the point that you couldn't engage a/p in an upset. It had been lost (Part 1 of episode), then some sort of apparent recovery (necessary to allow the a/p to be selected), then Part 2. Divides the upset timeline into two parts: at least in my head. He then pointed out the directive, the inference being that this is now known to some and they have acted.

Pt = Part in my Pt of the world
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Old 23rd Apr 2011, 20:11
  #3894 (permalink)  
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If Svarin is correct, and he makes excellent proofs, the Cabin Speed advisory, if it involved depressurization, would have been the signal of a more or less vertical descent. There is great resistance to this theory, but I have considered how an a/c can make an impact with the water in the way BEA describes. (I think they are substantially correct). It unfortunately makes En Ligne de Vol an absurdity.

With little forward speed, how do wings remain roughly level in rapid descent??

Angular momentum. At upset, the wing tanks were close to full, and fuel was being drawn from inner wing tanks, to observe the traditional practice of keeping the wings heavy as long as possible. Even the Aft HS Trim tank would be full, to squeeze fuel efficiency from an aft cg (In limits, of course). The wings would be the heavy parts of a four part pinwheel, and remain level (roughly) because of their relative mass. I believe this would alleviate any successful attempt by the nose or Tail to wobble the system into tumbling.

Tail low, one wing slightly low, (per BEA), the system contacted the water.
It did not contact nose into wind, and if the VS was still on the tail, this system would not have achieved any stability, it would have tumbled at one third revolution into its first lateral excursion, (At altitude).

This involves a fairly rapid lateral rotation, and of course is fatal to a "Nose First" aspect at water entry.



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