Like wfsp, I worked in aerospace (in engine test, structural test, and later aerodynamics). Unlike the vast bulk of software failures, which are annoying, embarrasing, or, at worst, expensive, aerospace failures have a disturbing tendency to be lethal.

Quality isn't a thing, so much as a process. And it's not something that can be added after the fact, or by inspections, or by testing.

Inspection (in the software world, code audits, code walkthroughs, etc) are one part; testing is another (and everybody here knows that coming up with realistic test cases is difficult). How to deal with defective components is another part (as an example, the famous Pentium floating point error). Specifications are very important. Manuals for users, documentation for maintenance, procedures for future upgrades, etc, are all part of the quality process.