FR24 has ADS-B information for QZ8501
https://twitter.com/flightradar24/st...840256/photo/1
From this we see that the FR24 last known position was seen at 23:10:57 at 3.996 s 110.232 e. This is much closer to the area where the big pieces are resting (the FR24 LNP is about 21 miles west of the debris location)
I tried to calculate speed for the last two position reports and came up with a speed of about 20 kts. This calculation may not be accurate as it may be affected by the timing of the ADS-B transmission (the sample period is only 36 seconds.) But it could actually represent the forward speed of QZ8501 in its last seconds.
If I back up and calculate the average speed for the last 100 seconds of FR24s' data I find an average GS of 329 Kts.
(3.996 s 110.232 e to 4.083 s 110.335e = 54,897ft)
(23:10:57 to 23:12:37 = 100 seconds)
54897 / 100 * 60 * 60/ 6000 = 329 K
The FR24 information provides a last known location that is much more in accord with the debris fields being reported.
(We never have been told where the earlier Indonesian supplied last known positions came from - primary radar or ATC radar.)