AF 447 Thread No. 7

[Diagnostic]

@Organfreak,

Hi,

Originally Posted by Organfreak

If they didn't recognize or respond correctly to UAS, maybe they would have done if the airplane had shouted at them.

That's exactly my view - maybe they would have responded correctly, since such a warning reduces the ambiguity about what is being recommended to them. For me, as with all the accident reports I have read over the decades, it's about...:

Originally Posted by Organfreak

Back to Swiss cheese: should we not plug every possible (known) hole in it? As someone already pointed out, the closing of any one hole in the Swiss you-know-what may have prevented this horrible crash.

Exactly


@chrisN,

Hi,

Originally Posted by chrisN

I have another wild suggestion; when the aircraft gives up flying itself because of UAS, instead of an audible alert (we know audible alerts don’t always get through, such as the stall warning, when the crew is in cognitive overload), how about intermittently clearing the glass cockpit of other stuff (which for AF447 crew did not help them at all) and putting up a big message; “You have UAS. At this height, use power and pitch” (or in other appropriate circumstances: “ Use memory items and QRH”)

I understand your expertise gives you a different insight than me into human factors (mine being commercial rather than aviation), so you could well be right - I'm not saying that the warning has to be delivered as an audible alert.

In my recent reply to Old Carthusian, I gave my alternative hypothesis for the PF's apparent ignoring of the stall warning. Even if you are correct that cognitive overload caused the stall warnings to be ignored (and I agree that this is plausible), a UAS warning on AF447 would have been delivered at least 5s before the first stall warning started (based on the CVR transcript), so it had a chance to be recognised first.


@gums,

Nice to see you back, sir

Originally Posted by gums

So crew becomes more and more and more of a monitor. But who does what when data is lost or is unreliable?

This "garbage in, garbage out" problem (as someone else described it!) is exactly why having an automated response to UAS is a larger topic, than having a clearer and more explicit warning about it, IMHO.

Originally Posted by gums

To appease the whiz kids we agreed to a big flashing "X" on the HUD. A year later one really agressive pilot flew right thru the big flashing "X" and augered. Least he didn't have 200 SLF items with him.

Any warning can be ignored, as your example graphically demonstrates. My point is that if AF447 had followed the correct UAS procedure it would have meant no zoom climb, no zoom climb means no stall, and no stall means no crash.

What I find so interesting is that crew not following the UAS procedure is a bigger problem than just AF447. As I said in another reply, are we just "someone having a bad day" away from another crew not recognising UAS and so not following the UAS procedure, in as dangerous a way as the PF in AF447? Could a specific UAS warning reduce the chances of that behaviour? So far, I don't see a compelling reason why it couldn't, and every reason to think that it might.


@RR_NDB,

Hi,

Thanks for the links in your "surprises" posting - they were all new to me. PM to follow when I get a few minutes

P.S. I just saw your new posting a few moments ago - nice summary.


@Hamburt Spinkleman,

Hi,

Originally Posted by Hamburt Spinkleman

In interim report no. 2, the section on previous unreliable airspeed events and in particular the 13 events that was examined closer, I see a factual listing of the technical effects and of the crew's handling/actions and nothing more. I see no judgment on whether the crew's actions were right or wrong and I see no intent of the BEA to infer any.

I politely disagree - these seem to be clear judgements to me:

"Four crews did not identify an unreliable airspeed"

(So 4 out of 13 UAS events were unrecognised by the crew, therefore by definition their actions were wrong as those actions were missing!.)

"For the cases studied, the recording of the flight parameters and the crew testimony do not suggest application of the memory items in the unreliable airspeed procedure:
* The reappearance of the flight directors suggests that there were no disconnection actions on the FCU;
* The duration of the engagement of the Thrust Lock function indicates that there was no rapid autothrust disconnection actions then manual adjustment on the thrust to the recommended thrust;
* There was no search for display of an attitude of 5°."

(So in all 13 UAS events which were examined in detail, specific parts of the UAS procedure were not followed - the lack of crews aiming for 5 degrees as a memory item, seems particularly worrying and particularly relevant to AF447)

There are several other places where you just need to compare what the crews did (as described by the BEA in IR2), with the actual UAS procedure showing what they should have done, and "join the dots".

Originally Posted by Hamburt Spinkleman

I think you are reading too much into it and I see no basis for characterizing the handling of those 13 events as inadequate, wrong, mis-handled or in-correct.

Unless you can show me where the 13 crews are described as correctly following the UAS procedure, then by definition, their actions were incorrect & wrong (and any other synonyms I have used), and so I consider my characterisation as justified by that evidence given by the BEA.

Please do provide me with your evidence that those 13 crews correctly & completely followed the UAS procedures (which would therefore contradict those BEA quotes above, wouldn't it?), and I'll happily reconsider my position.