Originally Posted by Propduffer
The exact point where the flight path intersected the ping ring was at about 6°32'34.04"N 96°42'17.66"E. this is about 20nm east of where the Malaysians have vaguely given it's position at 18:22. I accept the Inmarsat BTO data as accurate and thus ignore the Malaysian position estimate at 18:22.
There must be some mistake on your calculations because 6°32'34.04"N 96°42'17.66"E isn't on the ping ring.
I can't find anywhere that the Malaysians give coordinates for loss of PSR but using the map contained within AE-2014-054_MH370_SearchAreasReport.pdf it appears to be approximately 6.6°N 96.3°E.
If I project a great arc from just south of Penang Island through that point until it intersects the the ping ring I get 6°52'14"N 95°28'28"E. That works out remarkably well giving a constant ground speed all the way from the turn-around in the South China Sea to the 18:27 ping ring of 560 knots. I therefore can't see any justification for claiming that the 18:22 position is wrong.