Originally Posted by
GordonR_Cape
The Seattle Times article (from which the quote by @Zeffy comes) does not give many details. Indeed, designing a dual-channel system would be a huge task, but the B737 already has two FCCs running in parallel, and proving independent displays to each of the two pilots.
AFAIK only one of these is operational at a time, but they can be flight-switched by the pilots, so they must both be active.
I might completely have misunderstood the description in the Seattle Times.
To me there is a big difference between having two independent systems, not sharing the same ‘state space’, where only one at a time is controlling the hardware.
And having two systems operating in unison, sharing ‘state space’, where one is able to takeover bump-less in case the other fails-safe/silent.
The last system requires some degree of byzantine fault tolerance.