I relooked at the speed and altitude and this would appear that there was a definitive point of LOC. The aircraft is in the box maneuvering and comes out of a turn. It looks like the aircraft was under control and speed was controlled and then there is a rapid loss in both altitude and forward speed. That would indicate a spin and in the case of a Texan it would be flat as the tail is not stalled in a spin(trainer). That would explain the near vertical but flat impact. It would also happen post ejection to the aircraft.
Looking at the data it makes me question a failed ejection. Here is what the manufacturer's page says about the ejection system.
The aircraft has a through the canopy ejection system with a Martin Baker Mark US16LA zero/zero ejection seat. When the pilot pulls the ejection handle, they will always eject; if the redundant canopy fracturing system fails, they will eject through the canopy without injury.
In other words, the canopy glass has a charge in it that fractures the glass and if it fails the seat is designed to power through it. This is different than most designs where the canopy comes off the rails when ejecting and the glass is shed intact. I don't know enough about the seats to pass judgement but wonder if the seats were fired and the ejection sequence failed and incapacitated the crew.
Loss of a crew is a tragic event and I hope the accident investigation yields answers.
