CONF iture;
In my note to which you link I make a point which I think you have not fully considered.
To be sure, I wouldn't disagree with any of your comments as stated, as they all "make sense" in that they are, if I may use the term in a respectful manner, "motherhood" statements.
In response to the suggestion (to now include "AoA DISCR" as an ECAM message), who wouldnt' want "more warnings", etc? Perhaps it will be made one, who knows? But then what?
Let's take the TAM A320 accident case. Some argued that the thrust levers were closed by the PF but that the resolvers (six for each thrust lever) were somehow "at fault" leaving the commanded thrust at the "CLB" setting. Others examine the DFDR and see that the TLA for the #2 Thrust Lever remained in the CLB position and did what a wide-open throttle does - commanded almost full-thrust from the engine. The maximum discrepancy between two TRAs (Thrust Resolver Angles) is 0.25deg. Do we warn the crew if the angle exceeds this limit? In the TAM case, we might argue this, or not.
Two very different scenarios with vastly different antecedents and solutions. Do we warn the crew? If so, how?
More critically, (at Sao Paulo), what then, would be the meaning of a "THR LVR DISCR" ECAM message? Too soft an attention-getter when in fact the thrust levers were actually 25degrees apart? In that case, do we warn on engine thrust instead?
Another example....
I have had the
very occasional touchdown which was so smooth on a damp runway, (not the right technique, I know) that the spoilers did not deploy, rendering the reverse thrust unavailable. That's a bad situation and I knew exactly how to fix it immediately, but using the present arguments, do we now created an ECAM message, "#1, #4 WHL SPN DISCR" or some such message? Again, how to warn the crew, this time in a time-critical operation on a slippery runway. Do we warn the crew? How? Firm landings and proper technique, supported by a "runway distance to go" computer is another solution. Which to choose? Why, and does it work for all circumstances, (the Southwest B737 accident at Midway, for example?).
One might consider the thought that it is remarkable that this all works as well as it does, given all.
I am not being facetious or cheeky here - if you're going to ask questions about one system and take as a single example the Perpignan case as support for all solutions, the question then has to be asked about all systems equally, under all possible scenarios. We are approaching Vast circumstances and Vast responses.
The more important question is, "What makes sense for one system but not for another, and why?"
The critical point in this entire portion of the discussion acknowledges this very point while advancing an argument of which many seem to remain in denial - that "more warnings" does not resolve the original problem, and that next time, (as per PBLs post, part of which is reproduced below), it will be something else. At what point do we cease, if you will, painting devils on the wall and start recognizing some of the limitations of such work?
PJ2
Originally Posted by PBL #1354
Had someone said, before the Perpignan accident "you know, if two AoA sensors agree, falsely, then it is probably because ...... and we can handle it with ......." and persuaded everyone to go along, then that crew would have been saved. So let's consider doing that. Everyone predict the next twenty type-XXX accidents, suggest the obvious ways they could have been avoided, and write a letter to the manufacturer of type-XXX suggesting they implement those countermeasures.
If you think that is a silly idea, then we are on the same wavelength, because I think it would be silly too. But the people suggesting that Perpignan could have been avoided if only the aircraft had show this-and-this-and-this are still 19 accidents away from this recognition.