ATC data was used for the last part of the recorded flight according to a web based tracker, at an altitude of 1250 meters (4100',) however, ATC coverage may extend a lot lower than that? Somebody else might be able to provide that information. ADSB is great for providing many paramaters such as velocity, altitude, rate of climbą, and track all timestamped in high definition creating a 3 dimensional picture of what is going on. This data would be of assistance in the investigation.
Would it be fair to suggest all check and training activities take place in a radar environment or airports that provide ADSB signal reception to ground level?
From Airservices Website
