I certainly did not take it that the vertical descent rate could be as high or higher than the forward speed on impact.
Nor I, assuming (like you) that the statements were comparative (to a normal descent), just enhanced values of vertical and typical or somewhat less than normal horz component...
One really cannot read too much into such subjective statements.
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With the VS separation analysis now proceeding to this high level (of credence), it seems on balance then, that the airframe was substantially intact at impact - and that the
exact break-up sequence on impact can never be fully simulated/modelled. Any impact angle and velocity that results in a separated VS, with similar support structure damage, is acceptable... there may be more than one set that fits the bounding conditions!
What matters, next... review the VS drift again making the assumption it originated at the crash site. Can that correlate with the estimated backtracked position of the slick?