jimjim :
Thing appears to be that on the aircraft type in question; the elevator trim *is* a "primary" control in that it is required to be varied for normal manoeuvering.
Thank you for enlightening me of something I've been flying for the past twelve years, 'cos that's really new to me.
Of course, mostly the pilots don't see the behaviour as "triming" (and it surely is not trimming in the traditional sense) since it gets taken care of by the computer. Except this time.
Do you see anything wrong with the Mach trim you'd find on most of the pre-FBW airliners ?... I thought not... So where is the difference ?
Can anyone see a reason that the seperate trim control lever/wheel/switch exists on this type? Since the stick commands "g" (or load factor) surely the seperate trim control is anachronistic? Does it belong in the same bin as the mixture levers?
It's because of the different reversions to the flight control laws.
I've seen it used in Alternate and I've seen it in direct and it's your only choice in emegency back-up.
Although it's available, I've never seen it used in normal law.
These things have already been explained earlier on this thread. How you missed them is beyond me.