Vessbot.
My comments was not directed at you specifically. It was a generalised statement. Too often on these pages we see explanations so detailed that the original, or supposed, point gets lost. This is such a case.
The essence of FLCH is quite simple. If you want to go down (the most common use of the mode); wind down the selected altitude. Press FLCH.
From memory; (I no longer have access to FCOM of other relevant data), speed window will be at, or will open at, selected speed, (if it’s not what you want, change it). AFCS will endeavor to get the A/c down to that altitude in (I think) 120 seconds. It will maintain selected speed (speed lock) and adjust thrust to suit, vertical speed will be whatever, as it is a function of the other parameters, not a controlling function. FMA will show FLCH and THR until AFCS is done with adjusting thrust, when it will then revert to HOLD.
HOLD will be maintained until either altitude capture or G/S capture, (or ground contact hello ASIANA). It will then wake up and do its thing as appropriate. Throughout the procedure, whilst in HOLD pilot input to thrust levers is possible and appropriate for vertical speed adjustment.
Knowledge of what is happening in the relationship of trim and elevators as has been referred to in this thread, are outside of the control of the pilot, is inconsequential to the operational outcome, and only serves to confuse. The system is well designed and normally works as advertised, provided the inputs are appropriate. In 17 years on type, I never once thought about which control surface, is doing what, to achieve the outcome that I am requesting of the whole. That’s designer ****. Not pilot ****.
Looking at your second post.
Para 1. Sometimes it is a virtue rather than a fault
Para 2. In FLCH, V/s is not a parameter It is a consequence.
Para 3. Airspeed is “locked” (speed window) V/s is a consequence.
Para 4. I deal with what I can see. There is no target V/s. Speed is “locked”. Pitch will vary to maintain speed. Speed is “locked”.
Para 5. Once the FMA goes to HOLD pitching will only occur to restore Speed. The Auto throttle is out of the equation until Alt Cap or G/S cap, when it will wake up and do its speed thing. There is no target V/s.
Para 6. Que?
Para 7. Exactly. This issue is one generated by overactive minds.
As I scribe this, it has become abundantly obvious that you have missed the point that the Auto throttle is out of the equation once the FMA transitions to HOLD.
Maui