Here's the snip from the FCOM I have been given from one of the pilots here:
I can't find any clear reference to "auto-trim" until "Direct Law".
Note that the THS seems to follow pilot inputs except when AoA "protection" is active, and in our case HAL decided AoA was irrelevant. GASP!
Maybe
A33Z can help here.
So I'll throw my vote in with several here that the THS auto-trim feature did not help the situation, and may have contributed to the stall entry and remaining in the stall unless the pilot commanded nose down/lower gee than "one".
I continue to iterate that the 'bus system is not an "attitude" command but a gee command. Because HAL corrects for pitch attitude, the basic one gee command is "corrected". So you think the jet is trying to maintain an attitude, but that's just a result of the corrected gee comand. Additionally, without auto-throttle, the only speed stability is when drag equals thrust, and it is not what we old dinosaurs were used to when the plane tried to achieve the trimmed AoA ( and resulting drag versus lift properties).
So way I read things, the plane would have trimmed for one gee corrected for 10 or 12 degrees pitch even if the pilot let go of the stick. The THS eventually reaches max and.........