Originally Posted by
bsieker
In general, the industry does, and overall does a very good job of it. Input value filtering is normal, and even the A330 that nose-dived in cruise had computers which did. It was done inappropriately, but most of the time the erroneous values were rejected.
The problem here lies much earlier, in specifying the requirements for MCAS. More specifically, the failure modes and the severity and likelihood of each were not properly analysed.
Au contraire. Aviation is the industry which mandates appropriate techniques. They are well-known, and used.
Add-on systems that bring airliners back into compliance, which are not by themselves aerodynamically completely compliant to regulations, are literally as old as jet airliners themselves. Many types have stick-nudgers or stick-pushers, and they work fine, and are perfectly sensible to use. But that does not mean one can skip due diligence in developing them, which includes a thorough risk and hazard assessment.
Bernd
I know some plane computers are properly built and programmed and that part of the industry works ok. That's exactly what I meant with 《we know how to do it》.
What I meant is that there is a 《all or nothing》spirit that doesn't quite cut it. Either is a 8 year development with millions of man hours on it ,or a terrific patch that looks like done overnight. No middle ground.
I'm all in for a cheap patch. The cheapest possible, no need to doom the plane and start over. But if the computers in the plane have no room for improvement, a software patch in 1980s style is not going to be enough. We need sanity checks, cross sensor checks and history checks on ALL sensors. Not only AOA.
Precisely, no software patch will fix the issue of mcas being useless for real life (too slow).