Thomas Borchert wrote:

Hmm. I don't quite get it either. What DO you mean?

Sigh, ok. Replace "mistake" by "is to blame" and then you might
understand what I've meant.

If somebody is given a task which is impossible to accomplish, then who
is to blame? The one who failed or the one who gave him the task?

(Besides, the controller saw and corrected his mistake. Pretty late, but
still in time. Had there been no ACAS, then there wouldn't have been a
midair. So the controller didn't fail. And, before you ask: I don't
blame the russian pilots, either. I blame the one who is responsible
that they hadn't received adequate ACAS training.)

Stefan