we fly south into indonesian airspance and north (actually north-east) from JNB regularly. we seem to be able to get our desired level most of the time.
one area i can think of requiring one to think of climbing above optimum to avoid getting caught low is eastbound from turkey into iran. because west of turkey, you have the luxury of RVSM levels but not in iran. therefore, it is advisable not to be caught cruising at a non-RVSM level prior to iranian airspace. to make matters worse, you also transition from a BRNAV area into non-BRNAV requiring 10-min separation (officially at least as over the last one year they have tried to accomodate acft down to even 5-6 mins separation)
SR
noise unit,
i think i might have misunderstood your earlier question. our procedure on climb derate is related to selection of derate-TO. once a derated-TO thrust is selected, then the appropriate derated-CLB will too be selected. we are then not to alter the CLB thrust selection (select a higher CLB) as this could mess up the noise abatement procedures out of certain noise sensitive airports.
any changes in CLB thrust when in the climb are usually ATC related.
SR