PPRuNe Forums - View Single Post - AF 447 Thread No. 10
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Old 7th Sep 2012, 00:39
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infrequentflyer789
 
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I haven't had time to be on here for a while, looks like it's got interesting and informative again, but the magic "DSP" solution is getting a bit silly.


Originally Posted by RR_NDB
Worse than that is complete loss of SA due (partially) misleading info presented by the System to a (non properly trained) crew after erratic and inconsistent data contaminated System
Exactly what misleading info was displayed prior to the stall ?

As far as I can see the only misleading info at that point would have been speeds which were briefly too low before they disappeared. Why would seeing a suddenly low speed lead PF to stick the nose 15deg up ? If, prior to close of monitoring window, the indicated speed had been M1.5 then I could see a point, but it wasn't.

Delegate to the crew the task (as per Airbus SAS) is an error. Using proven DSP techniques an A/C subsystem may warn on impending UAS.
What proven DSP techniques would this be ? You keep mentioning DSP as if it were some kind of magic that Airbus engineers have never heard of. It's not magic, and of course they have.

Read the Airbus text properly - it states that one human cannot explain to another the set of rules for determining UAS, because it is too complex [it seems so complex that some humans cannot write a coherent procedure for dealing with it either]. Yet with your "proven DSP techniques" the machine can solve a decision problem that humans can't.

That's not DSP, it's AI, and it doesn't exist (at least that we know of). I doubt very much that we will have it any time soon either (I may have been out of DSP research for 20 odd years but I know people still in the field, and in machine learning / AI).

It's not a beancounter problem that we don't have this kind of tech either - the amount of money and brain power thrown at it is enormous - it is hard (and maybe impossible).

And deterministically inform of an important issue.
And how exactly does that stop the crew stalling the a/c when so informed ? How deterministic ? What level of false alarms ? How would crew reaction to a false UAS alarm be different to crew reaction to a real one [i.e. how many 447s are you going to cause] ?

What exactly is the rest of the a/c system going to do when it gets your DSP warning / alarm ?

- drop the a/p (you can't keep it in on suspected-invalid speeds) ?
- drop the protections (ditto) ?
- change control law (you aren't proposing a new FCC, just a new UAS detection, right) ?

And is that not exactly what happened ? And what did the crew do as a result ?


I posted several times this earlier

PS2

DSP and Signature analysis comment by andianjul:
If only repeating it made it right, or made it that simple.

Let's try some real info shall we ?

https://data.epo.org/publication-ser...45&ki=A1&cc=EP

Note that:

1. It's a patent so it's a PITA to read - but it gives us the benefit that its contents are legally stated under penalty of perjury (I think - may vary a bit with jurisdiction).

2. Note the filing date. This is state of the art, and post-447.

3. From the background statements on P3:
There is currently no reliable system and method for detecting whether a pitot tube and/or static port is
either malfunctioning or is indeed blocked by any of the
aforesaid debris
4. The technical detail clearly states at least one reason why the suggestions you've made and linked to above are somewhat over-simplistic (being kind).

5. The proposed solution is not DSP (it might use it but it is so insignificant that DSP is not mentioned). It's about the sensors and the physics. Always assuming this idea even works at all and at an acceptable error rate [neither of which is a requirement for filing a patent]



Finally, this crew knew they had UAS - "we’ve lost the speeds". That isn't the problem.

To what level of conciousness that knowledge penetrated at that time of night may be relevant - neither pilot seems to have processed "15degrees up at MAX ALT".

More relevant, however, is that when correct speed information came back (30s) and needed to be acted upon (in the window before they went so far out of the envelope that all airdata was bunk), it was (probably) not believed.

Detecting and alerting UAS is only (or less than) half the problem - you also need to detect and inform when the UAS event has ceased.

Feel free to post your patent number when you file :-)
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