So, imagine a day when the inbounds from the north outnumber those from the south. 2.5dme spacing is used and a run of 3 aircraft are packed at 160kts on 27R. Meanwhile on 27L there are few arrivals, and the (about to become) villain of the piece is slowing (slowly) from 210kts to 160kts. If this aircraft blunders towards the north, 2 or perhaps extremely 3 aircraft may need to fly a breakout.
There are some issues in that. I have to dash right now but I'll get back to you.
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