That's all very well but you are not attempting to answer SLR737's question.
RTFQ old chap.
8che,
I have read the question, all right, and given a clear answer, you cannot "demonstrate" (as one poster puts it) that you can land in 60% of the factored LDA, because you are not an experienced and current test pilot, with a flight test aeroplane, using the rather brutal handling techniques that established the unfactored distances in the first place.
If you attempt to land where the actual landing distance available in only equal to the nominal unfactored distance,
you will go off the end, with the consequent almost certainty of damage to your aircraft, which will almost certainly end you career if you are the PIC, and expose your passengers to entirely avoidable risks, which is what, in public, you will be canned for.
The "it was legal" defense doesn't work in real inquiries, let alone the court of public opinion.
Tootle pip!!
PS: I must have a look at the current figures for aircraft runway over-runs (not just Indonesia), but I think it will validate what I have said about landing performance, even when the runway in not obviously limiting.