Hi Crash One... I don't see how the Approach speed has any connection with the distance of the Back-track. As long as you put the wheels on the tarmac, at the Piano Keys, at Vso, it doesn't matter two hoots what your speed was half a mile before.
There is one other anomaly, when we use the term 'speed over the fence'... It all depends upon where the fence is. For most of the airfields where I fly, the fence is 400 to 800 yards from the Threshold, plenty of space to loose many knots down to Vso. For pilots where the fence is at the threshold, they have to make some fiddle-factor adjustments.
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