Coverage depends on ground receiver reception and is not a complete picture of traffic.
The hex code is the aircraft's ICAO 24-bit address, broadcast by its ADS-B transponder. It is the key used to match live position reports to this registration.
The loss of engine power for undetermined reasons.
failure of the pilot to maintain safe altitude/clearance from the terrain. Factors relating to this accident were: the hazy weather condition, the resultant difficulty in keeping the other airplane in sight, and the pilot's diverted attention, while looking for the other airplane during the airshow routine.