Given that the distance from IGARI to Penang is 222 NM, there is no requirement for MH370 to commence a descent immediately after the turn back.
You say that with such authority. Ok if there is no requirement is there anything else that you can think of that might have MH370
needing to start its descent?
It hasn’t reached the VNAV Top of Descent point from FL340 / 294CAS, for an ECON desc speed 268CAS in nil wind and without a Penang STAR or approach loaded.
I like all the numbers used but without an FDR or CVR or any clue at all, what makes you think they are the precise numbers that MH370 used on its engineer/FA/expert flight simmer programmed descent to Penang?