Aaron Hogue (of Hogue Holsters, knives, stocks, etc.)...no “G suit” capability in that Czech trainer with an upgraded engine. R.I.P.
https://www.hogueinc.com/about-us/
http://hogueairforce.com
Local airline pilot (near Reno/Sacramento) speculates on the cause:
Thanks for the links. I agree with the speculation of a high G blackout. The pilot made no attempt to recover the aircraft.