“Those planes did not crash because of defective code.”
Depends on the definition of ‘defective’. The code did what it was designed to do, but, as others have written in this thread, there was no anticipation in the design to deal with different situations and variables that might arise - like a faulty sensor, or disparate instrument readings.
“The code did what it was designed to do,”
That is the meaning of not defective.. What definition of defective could you conjure that would apply to this code?