You'd think aerospace engineers would have it down to reflex that things need to be fail safe. It's ironic a system designed to make the plane safer actually crashed the plane. That one should get an award for world's worst engineering.

Like any accident it wasn't just one thing. The maker implemented a safety system that was not fault tolerant, then the airline neglected to train pilots how to deal with a failure of that system. In fact that particular airline didn't even know the system had been added to their planes. Bad engineering, communication, and training still happens in the industry, but really it's pretty amazing how safe these machines are overall.

Pilot error is still the cause of a majority of accidents. A big problem is bad pilots that don't pass regular exams can slip through the system because of management deficiencies. Like pilots it happens in the medical industry where bad doctors or nurses just get passed on from one hospital to the next. Employers fail to do proper checks on previous job performance.