Next steps for tonight/today ...
Now we have the two red arcs.
There are (at least) two further constraints on final location under reasonable assumptions.
For now I think that we can assume that the plane did not stop to refuel in the early hours of 8/3 (but we may reconsider this later).
One is the flying time of less than 6 hours from near Penang to the final resting place (but presumably not much less).
The other is the fuel which would give a similar upper bound.
Thus we just need to draw another circle on the map of radius about 5000km centred on the last radar blip (off Penang).
Then we intersect circles and arcs and should get just one or two possible approximate locations.
Assuming the plane has flown straight. If it has flown zig-zag or circles that would not help.