@romasik...
Can anybody remind me an accident that happened in bad weather (near the minima) for the reason other then pilot mistake. I just can't recall.
Might be helpful if you make your question more specific. For example ... Do you mean in any phase of flight or just on final approach and landing... ?
( Note that the definition that I use myself is to view accidents as being 'a basically complex chain of events'. In that context there are no single cause accidents, which is also true for 'pilot mistake'. )