Somewhat off-topic but this has been bothering me: Several years ago I was in a program review and ended up in an argument with the lead Boeing software QA person for a particular group. The disagreement was because the person made a blanket statement that their QA process ensures there are no defects in their flight software. My response was that such a statement is absurd and that all software beyond some minimal complexity has defects. (A statement that I still agree with even though it is hyperbolic.) None of this has any direct relationship to the 737 Max issues as this wasn't even an airplane program but I think it points to what might be a cultural flaw if this attitude is widespread.

> ensures there are no defects in their flight software.

"Testing only proves the presence of defects, not the absence"

However, I think you are talking past each other here. The person you taled to was likely defining "no defects" to mean "all 1000 boxes ticked on the spec/testing protocol". They should call it "known defects".