Originally Posted by
MemberBerry
However this doesn't seem to be the case for the control column trim switches. In the FDR trace from 05:40:40 to 05:43:05 there are no recorded pilot trim commands. However, in this interval there was this discussion between the pilots:
"At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working."
This suggests the pilots tried to use the trim switches, but it didn't work and the command doesn't show in the FDR trace. If that's the case, it means the information about the thumb switch commands is recorded by the FDR from somewhere between the cutout switches and the motor.
You are assuming that "The First-Officer has replied that the trim was not working" means that he attempted unsuccessfully to use the electric trim switches.
It could equally have been him just confirming that just over a minute previously both pilots had agreed to disable the stab trim (05:40:35). So the electric trim switches obviously weren't going to work, and there wouldn't have been any point in trying them.