Folks,
There is already a thread covering much the same.
The operational length you require will NEVER be 60% of AFM or 60% of AFM plus 15%.
Note in particular my last substantive post, making the point of what the law currently is, in both FAA and EASA Land, versus the confusion re. advisory information, and all sorts of "good stuff" coming down the pipe, but NOT AUTHORISED BY LAW, yet!!
Wherever, whenever, the minimum landing field length required is the AFM figure, where the actual ( test pilot) demonstrated landing field length is 60% of the AFM length ---- but it is the AFM that is the minimum, specific Ops. Spec. requirements or regulation may require more.
When the method of establishing AFM landing field length changes, the results will seldom be less than the current figure, and frequently more.
As an example of the latter, the +15% on AFM for wet runways will no longer be at the discretion of the PIC, and it may be more than the present AFM + 15%.
Tootle pip!!