Indeed, part of this story is that the MCAS system was not classified as "critial" (i.e., a system which can cause a crash if it fails). If it had been, then it

Indeed, part of this story is that the MCAS system was not classified as "critial" (i.e., a system which can cause a crash if it fails). If it had been, then it would have faced additional scrutiny and they'd probably needed three AoA sensors and majority voting. Apparently the authority of the MCAS system was increased during development, with the criticality judgement based on the old smaller value. https://www.wsj.com/articles/faa-saw-737-max-flight-control-system-as-non-critical-safety-risk-11557831723 https://www.wsj.com/articles/faa-saw-737-max-flight-control-...