Thanks for your comments.
The graphs I've posted were intended as complementary to the information and the points made by a set of my previous posts, as at the time, I didn't have the graphs available.
The goal of those posts was limited only to the explanation of the relationship between certain elements that are under pilot control, the Stall Warnings and the confusion in the cockpit.
I have not made any claims of completeness on the set of graphs, so it may be the case, that more graphs could be added for more information.
The reasons of WHY the STALL WARNING functioned the way it did was a NON-GOAL, was not in my intention to explain with those graphs, and post.
An analysis of WHY the STALL WARNING functioned the way it did, can be a topic for a different post, and set of graphs. Your suggestions are useful for such a set of graphs, and post.
I think, these clarifications should help with the use of the word "omit" as well.
Originally Posted by
GarageYears
airtren:
But you omit two key parameters from your graphs? Airspeed and AoA.... and since these two are fundamental to the generation of the Stall Warning itself I think you are painting a directed picture.
Take a look at the BEA data and it is clear that the Stall Warning basically follows CAS - the rest is coincidental to my eye at least.
Take just one Stall Warning occurrence - the one centered around 2.14.00 - on page 107 of the English version of the 3rd Report.... and exactly coinciding is a period where airspeed becomes greater than 60 knots. There is clearly some hysteresis around the airspeed value since short periods where CAS exceeds 60 knots don't trigger it, but when the value is there for a 'reasonable' period.
I suspect the problem is that excessive AoA leads to invalid CAS due to pitot characteristics - effectively the dynamic pressure is no longer being read since the inlet aperture is no longer 'inline' with the airflow, and the drain opening is exposed... all in all the problem is a vicious circle, driven by the insane AoA value.
I could add, that if a STALL is possible with the a/c in a recoverable situation, a reliable, and 100% working STALL WARNING mechanism would increase the chances for the recovery to succeed.
If we consider the causality chain, that the STALL is caused by a "lack of sufficient lift", which is caused by the range of the actual "airspeed" and/or "AoA", it may become clear that if we could sense, or measure directly "the lift", and thus the "lack of lift", then that would be perhaps an additional parameter, that would add to the reliability of the STALL detection/calculation mechanism.
Once IN THE STALL many of the systems necessary to understand the situation are compromised.
Solution = avoid STALLING