Originally Posted by
Eesh
I have a stupid question, may be better to get it discounted early.
When MCAS is active, could there be any difference in the control of electric trim from the trim switches at the Captains side and the FO side?
The Lion air Captain was winding back the trim wheel for seconds. The FO who was watching this all the time suddenly decided to use only blips, looks strange.
-Sanish
Good question.
I have another question: if the FDR trace is for the switches, why are there only two traces (Trim Up-Man and Trim Down-Man), instead of four: one pair for the captain switches and one pair for the FO switches?
In fact, if they wanted to, they could record even the position of the individual halves of each switch, and that would require 8 parameters to be recorded on the FDR (4 up, 4 down).
The fact that there are only two traces for manual electric trim, one for up and one for down, seems to indicate that those commands are recorded "closer" to the motors than the switches, at a point where it is not possible to differentiate between the sources of the commands, the captain's or the FO's switches, let alone their halves.