as everything else the factored Required LD is only applicable at dispatch unless overruled by operators OM. In flight only actual LD matters which, as pointed out, conform with the current legislation doesn't reflect the reality. Operational landing distance concept is much more than just a mere 15% factor. It's a fundamentally new approach to actual landing performance assessment not only on the line but during certification as well, in particular on contaminated RWY. Moreover it finally binds the operator to implement realistic assessments online on daily basis. As for reversers, well there're there to be used and if they do shorten the landing distance then I don't see any reason why it shouldn't be accounted for.
