The last CONFIRMED contact with satellite was at 8.11am local. That is 7.5 hours after take off, which would be at the extreme of suggested range, based on fuel suggested fuel load.
Anywhere that they might have made a quick stop, had a fuel truck waiting (or even siphoned from another plane) and taken off again?
Or have we ever gotten an accurate accounting of just how much fuel was on board when they initially took off?
This whole thing seems to be planned too well to cut it that close on fuel. That would be taking a big chance with unfavorable winds, etc.