[ventus45]

I think there is a fault in the logic of assuming that high altitude cruise and speed was maintained between the 5th and 6th arcs (22:41 and 00:11).
That is 90 minutes.
Having the aircraft still at cruise settings at 00:11 (given the fuel model estimates) effectively requires either a deliberate suicide dive from altitude with dry tanks, or a ghost flight that effectively ends the same way at 00:19.
I don't buy either, yet this has been the consistent narative from the ATSB, until recently.

Now the ATSB seems willing (well, unwilling really) to begrudgingly entertain the idea of a ditch, (for political reasons) by assuming an un-powered glide beyond the 7th arc, implicitly from high altitude.

Such an idea is pure disingenuous stupidity.
It is a sad state of affairs that an ignorant media and public seem willing to embrace it.

To be blunt, if one was a "deliberate vanishing ditcher", you would need, and would have prepared, an excruciatingly detailed, meticulous plan, (he is acknowledged to have been "meticulous") that melded location and the sun into a workable "get there dark", and "pop out into sunlight at the last moment" to ditch.

To successfully ditch, you need:
(1) FUEL for a controlled flare and ditch, and
(2) TIME to:
(a) descend from cruise altitude to near surface,
(b) reduce speed and "configure" for the ditch, and
(3) Light, to see the surface for the ditch.

The aircraft MUST therefore descend, in the dark, EARLY, well before 00:11.
If the fuel models are any good at all, and if it was a deliberate ditch, it quite simply could not still be at cruise height speed and heading 190 at 00:11.
If it was, then:-
(a) the fuel model is wrong, or
(b) there was more fuel on board than we have been told, or
© the FMT was further south than we are told, or
(d) a combination of the three.

My DITCH PLAN, as a "mission planner", is as follows.

My "cruise south" on 190 true ends, repeat ends, at 23:40.
I have planned on being at low level flying 097 true into the advancing sunrise, but turning (just before actual sunrise) to ditch on a crest.
So, my plan is:
(1) TOD (top of descent) is at 23:40, still in "the dark", I reduce to idle, and turn left from 190 to SE (135 true) and commence descent.
(2) Descend from FL440 to A040 = 40,000 feet in 20 minutes = average ROD -2,000 feet per minute, reaching BOD (bottom of descent) at 4,000 feet at 00:00 zulu (precisely) (he is acknowledged to have been "meticulous").
My / his Speed at TOD was/is 480 knots-gs, reducing during descent iaw normal descent schedule M/IAS slowing to 250 KIAS by 4,000 feet, effectively eqals ground speed then, assuming no wind.
(3) At 00:00z I am at 4,000 feet, speed 250kn, AND (most importantly) I am still "in the dark", at the beginning of twilight.
This allows for "reconnaissance" of the intended ditch zone out my left window, looking for lights of any shipping. There is none, all good, proceed.
(4) Turn further left to 097 true to run directly at the advancing terminator, whilst slowing to 180 KIAS and configuring flap 20 for ditch.
(5) As twilight rapidly gives way to light, surface becomes visible, so now assess sea state and determine:
(6) swell alignment. Wave crest axis is 330-150.
(7) so at 00:10, commence turn left to 330 to "line up".
(8) The 00:11 ping occurs during this left, descending, slowing turn.
(9) Straighten up on 330 and establish low powered gentle descent, (no landing gear drag) at normal 600 fpm at 120 knots to 600 feet RA, then reduce to 100 feet per minute to 100 feet RA, then reduce ROD further by visually using the aircraft shadow out the left window at relative RED 053 (277 true) to minimum ROD whilst simultaneously bleeding speed to absolute min 90 knots, to ALIGHT on a crest AT NEAR ZERO ROD at min speed, and CUT at 00:17.
(10) In other words, the actual ditch position is BETWEEN the 00:12 and 00:18 terminators, probably closer to the 00:18 terminator.
(11) Engines drown, APU starts.
(12) SDU reboots, partial logon at 00:19, then APU drowns from waves flooding inlet at tail.
(13) She sinks in minutes - say before 00:30.