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AF 447 Thread No. 7

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AF 447 Thread No. 7

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Old 10th Apr 2012, 18:19
  #1341 (permalink)  
 
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ACARS could be used for UAS characterization?

On indications i would suggest: FLASHING (or warning by other suitable means) when TWO are different. If THREE are different better to not be presented to crew: Likely just GARBAGE with "MISLEADING CAPABILITIES" like occurred in the Thiells 727 ferry flight.

Will comment further your recent posts on this, IMHO very important issue:


Preventing loss of CONFIDENCE, CONFUSION and (potential) MISLEADING.

ACARS (currently) can be programmed to report UAS not observed (or observable) by crews?

Beacause AFAIK UAS is being kept by the System as an "INSIDER INFORMATION". A privilege of the System. (as per mentioned Airbus SAS paper crew must scan...)

This IMO could even be considered A Design Flaw*: Simply because at reduced cost (negligible cost) you can do better:

1) System PROACTIVELY helping crew (informing UAS onset) and

2) system CLEARING the issue (for a likely busy crew: scanning, trying to correlate, etc.)

Remark:

A DSP (Digital Signal Processing) on ANALOG (raw) air data (before ADM) can seems as miraculous (even for us, EE's)

*

Or lack of an important AID to help crews yet submitted to dozens of Air Speed anomalies closely related to the sensors being used.

In the Thales (now formally obsolete) equipped A/C an effort (Review or upgrade) would be essential.

The mere replacement to the US probes ("BF") IMHO is not enough. Wait to the final report (and it's consequences) shows how slow the bureaucracy is.

In the meantime pilots are at risk in not detecting timely a sensor limitation in a design with no redundancy.

Last edited by Jetdriver; 10th Apr 2012 at 23:20.
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Old 10th Apr 2012, 19:56
  #1342 (permalink)  
 
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RR_NDB:


Beacause AFAIK UAS is being kept
by the System as an "INSIDER INFORMATION". A privilege of the System. (as per
mentioned Airbus SAS paper crew must scan...)
IMO this is posted before by several posters:

Crew must scan because system has limited pre-programmed parameters to make logic decision to decide which ADRs are wrong (if dual or more ADRs are wrong and different).
In such a case a single good source can be rejected by the system.

Human (and Crew in specific) can add or skip parameters to make a - better! - logic decision on wrong and different information.
They have to isolate the faulty sources to prevent the system for rejecting the only good source and using the wrong sources.

Nothing to do with 'INSIDER INFORMATION', unfortunate during the fase 1 (as determind by BEA) the UAS of 2 or more sources lasted not long enough to trigger the ADR DISAGREE ECAM message (needs 10s to prevent spurious warnings).

in fase 2 (Continued Stall warning fase) all the speeds returned to consistent values.

In the start of fase 3 - when AoA became invalid due to hi AoA (resulting in CAS NCD) the ADR DISAGREE triggered because the UAS lasted more than 10s.
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Old 10th Apr 2012, 20:20
  #1343 (permalink)  
 
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A33Zab

"In the start of fase 3 - when AoA became invalid due to hi AoA (resulting in CAS NCD) the ADR DISAGREE triggered because the UAS lasted more than 10s."

The Pitots do not pivot, and what caused the AoA vanes to read high, caused the airflow to glance across the aperture of the sensors, dropping the pressure within. Are you saying that at remarkably high values of AoA, the speeds can be trusted regardless of UAS? And not be falsely quite low, together?

?

Doesn't BUSS moot this arduous thread?
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Old 10th Apr 2012, 21:00
  #1344 (permalink)  
 
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Time required to "help the System"

Hi,

AZR:

So, crew must help the System in this situation?

With good DSP processing of THREE sources (that always must be considered suspect) the crew could instead be "helped" by the System.

Sometimes (even on A/C) you use 5 redundant elements. E.G. in Airbus SAS design.
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Old 10th Apr 2012, 21:22
  #1345 (permalink)  
 
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This could be improved

[/quote]the UAS of 2 or more sources lasted not long enough to trigger the ADR DISAGREE ECAM message (needs 10s to prevent spurious warnings).[/quote]

There is room for improvement. Time duration is ONE of the information a good DSP can use to generate reliable output.

And an spurious warning (threshold can be "digitally calibrated") is not a problem. The scan could verify easily is a "false positive".

I prefer a rare "false positive" than not being informed on UAS happening in the background. And worse: Generating DECISIONS for short duration anomalies.

What i don't agree:

A short duration anomaly be capable to reconfigure the A/C without ever telling what was happening. This sounds "opacity" capable to difficult crew operation. There are reasons for that? Let's work in the details and pilots could benefit from "state of the art" resources.

Last edited by Jetdriver; 10th Apr 2012 at 23:21.
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Old 10th Apr 2012, 21:34
  #1346 (permalink)  
 
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rapid TAT increase

Please forgive my off the track intervention, here but a A-330 pilot just told me that his company had some rapid TAT increases , one of which in they lost 4000 feet.

Rapid TAT increase while in cruise ?could someone explain this ? ?


" total temperature, which occurs on the wing leading or nose of your aircraft. The total temperature depends on the local, atmospheric, static temperature and on the velocity of the aircraft"


Please excuse if addressed earlier no time to read all the posts.
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Old 10th Apr 2012, 22:32
  #1347 (permalink)  
 
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While we are debating the 'minutiae' associated with the AF447 accident, I have been doing some work on a Search Engine that will selectively search the individual PPRuNe Rumour and News / Tech Log threads on the subject.

At the time of this post, there have been 13 substantive threads on the AF447 event, involving 25,184 posts. That doesn't include those posts deleted by the moderators, e.g. 949 were deleted form the first thread - Air France A330-200 Missing.

The BEA's Final Report will no doubt attract many many more posts!
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Old 10th Apr 2012, 23:34
  #1348 (permalink)  
 
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Impressive figures

25,184 posts and counting


The BEA's Final Report will no doubt attract many many more posts!



Administrators should prepare for DOS like (traffic exceeding thresholds)

So, this will continue for years?



Another reason for a case study
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Old 11th Apr 2012, 00:16
  #1349 (permalink)  
 
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Hi RR_NDB,
Administrators should prepare for DOS like (traffic exceeding thresholds)
Apparently the Air France A330-200 Missing thread recorded its maximum server traffic of 11,419 visitors at 14:46 UTC on 1st June 2009.

I wouldn't worry.
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Old 11th Apr 2012, 01:01
  #1350 (permalink)  
 
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Originally Posted by mm43
The BEA's Final Report will no doubt attract many many more posts!
Not too sure about that ... so too many to comment in the early days following a crash, but so little to read a final report.
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Old 11th Apr 2012, 01:28
  #1351 (permalink)  
 
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Originally posted by CON fiture ...
Not too sure about that ...
Perhaps you may be right - time will tell.

The link you gave I think was in relation to the A320 down on the Hudson??
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Old 11th Apr 2012, 04:27
  #1352 (permalink)  
 
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Cool

Hi,

http://www.pprune.org/rumours-news/3...ml#post4653807
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Old 11th Apr 2012, 10:36
  #1353 (permalink)  
 
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Originally Posted by Jimmy Hoffa Rocks
Rapid TAT increase while in cruise ?could someone explain this ? ?
The obvious reason is that the local static temperature increases. As the thrust at an RPM as well as the maximum thrust decreases with increasing ambient temperature, it could become insufficient to maintain speed and altitude.

Another possible cause is ice accretion on the TAT sensors. Depending on what sensors the engine control system uses, that can also result in a thrust loss.
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Old 11th Apr 2012, 11:52
  #1354 (permalink)  
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Thread #8 starts starts here.
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