Single signal used
I have a long experience with the safety of nuclear power reactors and their operation. We often have three requirements on a critical measured value.
1. At least three sensors should be in use and some kind of voting system selecting the most reliable signal. Redundancy-
2. In the optimal case all thre sensors should be based on different principles in order to avoid common cause errors.. Diversificaltion
Perhaps this kind of safety philosophy is too expensive to be used in modern commercial aricraft? All the required parts must be available today,.