Can you explain the logic behind this one?
How does touching down 10 feet beyond threshold equate in stopping 200 feet further than if touchdown occurred at the threshold?
First of all, (on a runway with an instrument approach) the "bullseye" in the TDZ (Touchdown Zone) is the big white 1000' markers. If you google up images of touchdown zone markings you'll see these usually marked as the aiming point. Practical Test Standards allow touchdown 250 short of or 500 feet past the big solid white markers.
So it's not _beyond_ the threshold, it's above the threshold or TCH (Threshold Crossing Height). I should have been more clear; sorry.
Standard for that aircraft and many others is to be 50' high crossing the threshold.
So if your TCH is 60' instead of the prescribed 50' that extra ten feet high will add 200 feet to your rollout.
Similarly, in that aircraft you fly the approach at Vref + 5kts and then reduce power so as to cross the threshold at Vref. If you are still doing Vref + 5, then you are adding 250 feet to your rollout.
The FAA is adding emphasis to all of this due to runway excursions on landing roll.
