Poor man. You can see how it could happen, so easily, if you were inexperienced or distracted or both.
Most log cranes now have legs which hydraulically rotate through 180 degrees, from vertically up to vertically down. Only after the leg is all the way up, does the slider retract into the subframe. All of this is controlled by the driver from the top seat, so they are clear of the moving parts.
I realise that on large cranes this may not be practical, as for one thing, they dont usually have top seats.