There are several smoking guns. The disabled transponder right at ATC handoff. The high-skill turn. The special flight path that skirts several jurisdictions, then blends with other traffic. The final turn off that path to somewhere far away. Lack of fuel being what ended the flight. The home simulator with the same flight path, i.e. one of these pilots has a history of flying this path.

Not something a passenger can do. Not something that can be explained as the first & last presentation of an unknown technical flaw.