Reading the NTSB report on Colgan Air Flt 3407 they seem to place most of the blame on the pilots, but there were two main factors in the crash. One being excess ice buildup on wings and props and two the sudden reversal in flaps from 15 to zero by the copilot without announcement. Even in an emergency I find it hard to believe that the copilot would cut flaps without announcing it to the captain who was trying to recover the plane. Meanwhile the captain ignored his stick shaker telling him to drop the nose and instead pulled up exacerbating the stall. Seems that if someone wanted to bring down this plane all they would need to do would be to disable the anti-icing system and then command the flaps to zero at the correct moment or command the stick backwards once a stall was initiated. This made it VERY easy to blame the crash on pilot error.
https:// airfactsjournal.com/2014/03/double-tragedy-colgan-air-flight-3407/