Map Update
D.S. Map updated with new route, thanks very much for the suggestion. This also raises the GS to 426 kots.
I have added the Due South Theory, which as it turns out, if the aircraft tracks via 200 NW Penang at a GS of 426 kts and then via BEDAX and hits the Inmarsat intercept line at 0011 (0811 local) still at 426 knots it works very closely.
But I still think that IGARI - 200 NW PENANG @ 426 gs is a bit slow.
fg32 the Inmarsat intercept look pretty good given the inherant inaccuracy in how precise it can be. What we do know is that there was no signal at 0111, so we have at last got a boundary to work with.