[toast0]

> I can't grasp how everyone involved could fail to realize that this statistically makes it less safe than only having one sensor.

This design is bad, but it makes sense as a update of the 737. The flight computer setup is each pilot gets a computer under their chair, each computer gets its own set of sensors and the computers take turns each flight. The flight computer is generally safe (i don't think it's been implicated in any crashes?), but that's because in case of issues in flight, the system usually will disengage and alert the pilot, or if the system takes poor actions, it will disengage when the pilot opposes it, or the pilot will disengage it.

Adding MCAS to the flight computer makes sense, the flight computer needs to be aware of it. It's understandable, but negligent, to add a new feature to the computer without considering the original design. The problem comes in when MCAS was not disclosed to pilots, doesn't disengage on errors, doesn't disengage when pilot input opposes it (partially by design), and can't be disabled except by disabling electric trim, which is more or less needed to recover from the error condition MCAS puts the plane into.

I think this is fixable, but the public information on the current fix doesn't include being able to turn MCAS off, so it doesn't seem like they've really done enough.