Well you got my bit in there, Gravity.
Remember going into Gatwick one morning in a Piper Arrow. Prat of a pilot that was flying it was at four DME travelling at a groundspeed of 60 knots.
Virgin 012 (747) came on and reported 12 DME.
I calculated the collision to occur just about at the threshold.
VS12 told to go around (I've never felt so ashamed). I was bugging the pilot to get on with it - but short of a fist fight on final, there was little I could do.