Radio Discipline
Intrance - Very well said, in such a case radio discipline has to be the primary attempt to keep control on the situation.
I have to correct myself in my earlier post as far as the failure mode is involved. Transmit only is quite another case.
However the Rules and Regulations of ICAO, Eurocontrol and DFS (German ATC) and the applicable procedures are all layed down in papers and well known to the controllers.
It might be interesting to find out who is responsible for the scramble of the fighters and that intercept of an civil aircraft, that clearly indicated itīs intention to proceed along itīs flightplan inbound to Zurich. An intention in accordance to the STANDARD Radio failure procedure.