C-C and A4 - you are risking 'frightening the horses' here with your tales of what dreadful tasks PNF would have to do to circle onto 12.
1) If you can land on a wet 30 with a tailwind you will be ok on a wet 12 with a headwind - therefore no re-computations
2) You do NOT need anything re-programming - a simple fix on the field and 2 mile circle if you must will more than do for a VISUAL manoeuvre - plus the 737 at least has a 'built-in' dotted white runway c/line in BOTH directions
3) G/A + missed does NOT change!!!! Do not confuse the great unwashed please
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If the P2 was ex mil and knew Islamabad, is it possible the mil had some sort of 'in house' proc for 12?