An automation system that doesn't validate input?
A decision was made by the system based on invalid input from RA#1.
It should have detected a sudden change from +1950 to -8 ft as invalid.
It should have compared with the available backup RA#2
If it wasn't designed in such a way, there is only one
conclusion and that is: a basic design failure!
The system should have detected:
-1- the impossible change in value
-2- huge difference between values from 2 inputs for the same parameter.
and at least alerted the crew for such a situation and/or
handled it properly by not using the invalid input!!!