Originally Posted by Bearfoil
If Manual Trim is necessary, why would it be annunciated in two separate colors, AMBER, or RED?
"Use Man Trim" doesn't mean that manual trim is "necessary" but that
autotrim is not working in this flight law => direct.
At first it is displayed flashing during 5 seconds, and later stay normal on the display, about its color, I'm saying that from memory. If one read "Use manual trim ONLY", hence big trouble, EFCS is not working anymore (mechanical back up) and you are left with trim only as pitch control.
Amber is the color of the crosses on the PFD removing the bank, pitch, roll limits. Red is the color of the Speed limit Flag (meaning no speed limits, no speed protection).