Originally Posted by
LowObservable
That's what I call "pseudo-triplex". I don't think the international authorities are buying it.
Perhaps I misunderstand your meaning, but I think triplex architecture provides for continued function in the case of a single AoA sensor failure. Not what the Boeing fix, if you can call it that, could do. By having two two AoA sensors in the loop, a disagreement can be noted and the MCAS function disabled. With two FCC involved, (not exactly sure why), additional failure modes may be detected and again, the function disabled. Not sure what pseudo-triplex means, but it does not offer what a full triplex architecture does.
Not sure if Boeing considered it, but one possible approach is to use non-AoA information from attitude and perhaps inertial sensors to detect a discontinuity in AoA sensor output as a validity check, and continue using the other AoA sensor if it is behaving normally. Not substituting the alternative attitude/inertial sensors for AoA, but only as a validity check. Only a thought, not trying to redesign the system.