Originally Posted by DozyWannabe;6617559; Post #1436
I'm not saying that the behaviour isn't problematic, I'm saying that I don't think that the return of the stall warnings is unambiguously triggered by the nose-down inputs.
If they happen at the same time, it does not really matter what's the trigger, the negative effect of the discouraging Stall Warning is the same.
Originally Posted by DozyWannabe;6617559; Post #1436
The only source that suggests that there was internal disagreement at the BEA is that one "La Tribune" article, and as such until I see some corroboration I'm going to be sceptical.
Well, if this morning’s news were not enough, ….
Originally Posted by DozyWannabe;6617559; Post #1436
Based on the evidence of a single press article that almost certainly comes from within Air France (which as an entity would benefit financially and in
PR terms from Airbus having to shoulder a larger percentage of the responsibility), I'm not buying that until I see some better traces - right now it looks ambiguous to me.
I don’t really care in whose court’s the problem. Now you have the BEA press release as well
I pointed you to the BEA Report paragraphs – perhaps I was a step ahead. The pointers in the English version are: page 76 paragraph 5, page 77, paragraph 8.
Originally Posted by DozyWannabe;6617559; Post #1436
That's fair - however as I said before, this is the only airliner to my knowledge that has been that far outside the envelope for that long, falling from that high - so at present it's not clear whether there is a deficiency in the stall warning design specific to the A330 (and by extension the entire Airbus FBW range), or whether this is something that needs to be examined on an industry-wide scale.
LOC and LOC due to STALL is an industry wide problem. Taking the ambiguity out of the problems that the pilots need to deal with at a STALL is a gain, which one truly appreciates only if found in that pilot’s situation!
I hope that the English version of the report, my posts, and other posts on this Forum will help you understand.
Originally Posted by DozyWannabe;6617559; Post #1436
Originally Posted by airtren
The message from the PF/NPF/CDB perspective was signaling a transition from NON STALL to STALL, when in fact the transition was from STALL to NON STALL.
Well, not quite - it was still stalled. If the nose-down inputs had been maintained before passing, say, 15,000ft on the way down then it might have stood a chance of coming out of the stall, but that's not a given. Remember that a stall warning is designed to activate before reaching the stall itself, so once it had picked up speed and the wings were unstalled, the warning would continue for a few seconds until it was out of the stall warning regime. That's not bogus, it's just a factor of the design.
Don't forget the STOP/STARTs of the STALL WARNING during the STALL, so it didn’t work the way you mentioned above.
The AF 447 pushed the system to its limits, and two problems surfaced (bugs):
a) the STALL WARNING stopped during the STALL, with a bad consequence, and
b) the STALL WARNING started during the transition from STALL to NON-STALL, with a bad consequence
With the current design, a STALL WARNING that stops means that the Stall condition no longer exist.
In case a) the a/c was still in STALL, which was a problem.
With the current design, when a STALL WARNING starts, it means that the a/c enters a STALL condition.
In case b), the PF commands were ND, to take the a/c out from the STALL. The warning of entering STALL meant that his command was wrong, and so he pulled back.
Edit: Note: PF ND actions can be looked at as the combination of Thrust and Stick, as the Pitch graph, in the areas significant for the Stall Warning OFF/ON/OFF on the Stall Warning graph, follow the Thrust and Stick graphs.
Originally Posted by DozyWannabe;6617559; Post #1436
Hypothetically, if they had successfully unstalled the wings, started bringing it back under control, but the extra couple of seconds of stall warning meant the difference between successfully pulling out of the recovery dive and crashing - would you be arguing deficient design on the part of the aircraft? Do you think Air France would?
Do you mean the case when the bogus mechanism delayed the recovery, to the point of the crash? As a frequent passenger, I would like to see the problem fixed asap, wouldn't you?
Originally Posted by DozyWannabe;6617559; Post #143
Originally Posted by airtren
You are missing the point, if you think, that the exact internal cause, or the mechanism of triggering the message matters. It does not matter, relative to the needs of the pilots, and state of the “a/c”.
It matters if you want to think about how to fix it.
Originally Posted by DozyWannabe;6617559; Post #143
Of course. it matters in the design/engineering space, and manufacturing space, but I was not referring to those. I was referring to the cockpit/aircraft operation space.
Originally Posted by DozyWannabe;6617559; Post #1436
In Normal Law you are commanding *rate* of movement in the axis rather than deflection.
Do you have, or can you point to a documentation on this?