In reply to Marc C:
> (In reply to Trangia) Black Diamond - apparetly the credits state that the harness was specially modified to fail. At the time Black Diamond (set up by Chouinard I think) were none too happy with the 'harness buckle breaking death fall' scene,
Unless I'm very mistaken the harness was a Bod; presumably the modification would have been either replacing or doctoring the buckle so that it lived up to its description - ie buckle! I'm pretty certain, though, that additional sleight-of-hand would have been required to obtain the end result.
For any sort of dangling activity like abseiling or, as in this case, a tyrolean, the standard means of attachment to a Bod - as used, if I recall, in the scene - would be via a locking karabiner clipped through both the buckled belt and the crutch strap/legloop; the latter is a closed loop so, no matter what happens to the buckle, and barring failure of the karabiner or the webbing, it would be impossible for the harness to become detached from the tyrolean rope. In the film, however, I think I'm right in saying that that is exactly what happens. In the final scene before the plummet of doom our short-lived heroine, having fallen out of the harness through buckle failure, is left hanging from it (inevitably!) by one hand, while the harness itself is now only connected to the tyrolean by the slipping buckle on the tail of the belt which is caught in the locking karabiner; the webbing pulls through, and down she goes. But what happened to the crutch strap? It would still have been through the karabiner. Presumably the effect relies for credibility on the assumption that most of the audience are non-climbers unfamiliar with the detail and usage of a particular harness.