DW,
Do we Know what the THS setting was in the cruise prior to the UAS event? The idea of the trim tank is to enable the THS to be fairly neutral. As far as I know, the THS was thus until the steep climb with rapidly-decaying (actual) IAS. Unless I'm missing something, there's no mystery in it. The FBW was doing its best – within its terms of reference – to comply with PF commands. The natural tendency of the nose to drop as the speed decayed was counteracted by increasing nose-up trim, provided by the THS in autotrim right up to the stall and beyond.
By the way, I've made a small clarification to my previous post.
Last edited by Jetdriver; 14th June 2011 at 14:09.