The 407 crash, from what I recall, the load master - who'd had somewhat dubious training it seemed - had hooked a long line to the helicopter belly hook without telling the pilot. The pilot took off without realizing he was connected to an immovable object at the other end, so when he was 150' into his take-off that is as far as he got and the whole show turned into self-destruct mode. Again, if I recall, said load master claimed he never attached the line, did a runner and was never seen again.