Originally Posted by bearfoil
I had always thought the purpose of Aft Trim Tank, or even "geographic" changes to enhance aft trim were intended to add Drag, "Lift" to the tail such that the AoA of the wing could be reduced, and lower Fuel Burn.
As a complement to what
Chris Scott wrote, here are some FCOM and FCTM references :
Originally Posted by Chris Scott
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.
At 29%, the CG was pretty far from the ideal 38%, but how much NU THS does it represent … As an estimate, I would go for anything between 2 and 3 degrees but I’m really not sure ... it would be something to look at the next opportunity, unless the BEA is ready to 'leak' it.