so what was the reason for the crash?
“Accidents arise from the unforeseen and often unforeseeable concatenation (linking) of diverse events, each one necessary, but singularly insufficient”. - James Reason
Look for the contributions which are part of everyday operations – those we take for granted, but might not fully appreciate the risks; e.g. ATM patterns, training crewing, use of automation, instrument scan, systems knowledge, etc, etc.
Then consider the unique event(s) which enabled these weaknesses to combine; and the ‘unsafe act’ (or inaction) which triggered the route to the accident – issues of human performance, didn’t see ‘it’, didn’t think of 'it' at the time, etc, and the likely reasons for these.
There’s no ‘cause’, only contributions; perhaps a significant one is the industry’s complacency in accepting operations which are too close to the edge of safety – they have become the norm, whereas each requires continuous risk assessment for the expected task and situation.