im "Down here", in South Africa. I work with some people who were on the tracking vehicle the night it happened. It was a techno 30 on a tracking vehicle, (I could stand to be corrected).
It was just a rehearsal. It was pouring with rain, and the stunt lady apparently did not want to do the rehearsal, but it happened anyway.
This accident happened not because of the fault of a grip, operator, or driver.. this happened because it never should have in the first place.