Ok, so blocked static on takeoff will cause IAS to start to under-read, the more you climb the more it will under-read.
So climbing at constant real-IAS, (which you would if you immediately identified IAS DISAGREE and pegged T/O attitude/thrust pending the memory items), you would be seeing a constantly decreasing IAS.
In the documents provided above, I recall noting that stick-shaker can be triggered (by the SMYD) by either AOA or IAS.
So that correlates with your experience: IAS trigger in this case.
What is interesting to me from this is that it appears that EFSM has also activated, indicating that it also has an IAS trigger. I haven’t found a reference for that yet, so thank you.
I also saw a note that the SMYD provides feedback to the FCC for windshear detection.
So it seems that the SMYD, in this case at least, is calling the shots, based on it’s inputs. It’s passing on a message to EFSM of “in stall”, based purely on a single IAS input. It may also have used the rate of change of that single IAS input (must be together with other ADIRU inputs such as GS) to trigger an “in windshear” message to the FCC.
I can add one sim experience of stick-shaker with blocked pitot on descent - similar in reverse. Blocked pitot on descent gives decreasing IAS until stick shaker. But never noticed EFSM operation. But it may have been active but went unnoticed because I didn’t try to pitch up at any point in the exercise.
EFSM gives no notification of it’s operation.
Question for you Austral: Did you get “FEEL DIFF PRESS”? According to documents above, erroneous operation of EFSM should give “FEEL DIFF PRESS”, which makes sense when you look at the FCOM schematic - it adds hydraulic pressure to one side of the Elevator Feel only (SYS A).
Simplistic analysis of EFSM schematic in the FCOM would lead one to believe that you should get “FEEL DIFF PRESS” under any activation of the EFSM, not just erroneous.
So does it inhibit “ FEEL DIFF PRESS” under “real” (non-erroneous) activation?
If so, it’s not yet clear to me how it does that, nor how it determines what is real and what is erroneous.
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Addendum:
Did you note any STS activity?
In my initial post I also noted that STS may also have a role in anti-stall behaviour. FCOM only vaguely hints at that. But the documents above indicate that it certainly does. In reading, it sounds like the grandfather of MCAS.
The vibe I got was that it might also override the FWD electrical limit switch, so it can trim to 0 units continuously. But... it cannot override the aft column cutout switch. So, the EFSM is partly designed to make it very hard for a pilot to pull the column far enough for column cutout activation, so as to allow STS to keep trimming forward until it either reaches zero or it saves the day.
Disclaimer: I’ve only skimmed the documents so far, I still need time to read carefully - so there might be gross misinformation or misinterpretations in my words.
Fascinating, thanks Astral.