Originally Posted by
B2N2
You should be at rotation speed by the time you reach the half way point of the runway.( which is kind-of-the same as 85% and 40% but easier identifiable)
But this makes no provision for the type of surface, condition of the runway, braking effect, etc. ...
Originally Posted by
B2N2
Better yet:
T/O distance ground roll + landing distance ground roll + 20% = runway length required. Using the values published in the POH.
I don't see this how this is relevant to the question that has been asked. Your answer seems to be to quite another question, i.e. "how might you calculate an accelerate-stop distance if you have performance figures in a POH but no specific graph for ASDR."
The thread question is quite different and relates to a visual "go/no-go" check during take-off of a certain speed against percentage runway distance. For aircraft using short strips, it is often the case that there is no POH performance data available anyway.
JD
