Originally Posted by
IAMORGAN
Could it be to do with crew duty times? There are strict limits. As I understand it, the commander can extend this at their discretion up to a certain limit. Keep in mind that SIN has 4 flight deck crew whereas KUL has 3 IIRC, which might make a difference.
I flew back from KUL a couple of weeks ago and it had 4 flight crew onboard. That flight was a little over 13 hours.
Interestingly on my way out to KUL the route had been over the middle east and central India. The route back was the more northerly route.