GobonaStick,
Why bother turning northwest, towards the Andamans, if you're only planning to head south and put it in the drink?
Avoided radar. If you are committing suicide but want an insurance payout for your family, you need to obscure your suicide.
Making everything look like a hijacking and ditching the plane in about as difficult of waters to search as you can find seems like a pretty brilliant plan to accomplish just that, imo.
I'll
really be impressed if we eventually learn the tail was drug somewhere along the trail to drop the black box away from the wreckage. (unbelievably unlikely, I know - but hey, look where we already are!)