BOAC:
aterpster - that, I think, is a world-wide system (not peculiar to 'this part of the world'), called (under EUOPS 1.975) 'route and area qualification' and all crews are so qualified. Category A is normally renewed by the annual recurrent line check, whilst Cat B and Cat C airports and areas have different training and testing requirements.
Although I am not familiar with the specifics of EUOPS 1.975, I would have presumed such a system exists. But, not necessarily for carriers in some parts of the world.
You are suggesting, I take it, that OPRN is a special category airport, possibly requiring a route check before circling is attempted or some specific 'company directives' for circling? If so, do we know that this Captain was so checked or trained?
It very well should be a special-qualification airport as to the use of Runway 12. The lack of straight-in IAPs strongly suggests some peculiar local restrictions or conditions. We know about the unusually close restricted airspace to the south side. I suspect there are issues about overflight of certain areas on the north side that could be better served by flight-track CTL procedures.
Perhaps you have opened a door onto this tragedy which may explain the apparent crew error. Perhaps someone familiar with AirBlue's ops manual could comment? I cannot see why a competent crew could not be expected to conduct a straightforward and simple CTL at OPRN (or any airport), but maybe herein lies part of the reason for this accident?
It's possible that the captain had never before landed on Runway 12 (or perhaps he had, but only in good weather conditions). That is no stretch of logic at all given the circumstances of this airport. In any case with monsoonal rain conditions, I submit CTL is a very demanding, difficult maneuver for the most competent of pilots. The egress to the missed approach procedure is no small consideration among other factors.
For all we know perhaps the captain was flying an ad hoc visual maneuver attempting to avoid known (to him) areas "unfriendly" to overflight. Also, from earlier comments it appears there are landmarks that can be confused with the airport, at least during rain conditions, which rain could have easily intensified as they proceeded towards the hills.