It's my opinion that you need to set our your terms before you can have any meaningful examination of what is and what isn't pilot error.
It's like cause of death: cause of death is always cardiac failure, but it would be absurd and pointless if we said that someone who got drunk and inadvertently shot themselves in the head whilst trying to scare a pigeon off their TV aerial, had died of cardiac failure rather than gross stupidity.
We tend to look at the last point at which the pilot could have said no, and then assess whether it was reasonable that that moment was missed.
To say (as was said in the other thread) that *all* accidents are pilot error is to reduce the examination down to a point where it's pointless bothering with. In Sioux City (foolish) people could argue that some of the deaths were attributable to pilot error. That would be literally true but clearly absurd.
What are we saying is the meaning of Pilot Error?
Is it, for example, a pilot making and acting on a decision that a reasonably skilled pilot would not have made had s/he had a chance to examine all the options carefully?
I'm just offering that as a starting point. I just made it up. It may be full of holes - feel free to take it to pieces if you've got something better.