Incident: TAROM B737 over Germany on Sep 6th 2018, loss of communication prompts intercept
https://avherald.com/h?article=4bd560ae&opt=1
A TAROM Boeing 737-700, registration YR-BGG performing flight RO-371 from Bucharest Otopeni (Romania) to Brussels (Belgium),
was enroute at FL400 over Germany when the communication with ATC was lost following a hand off.
Two Eurofighters were dispatched to intercept the aircraft near Frankfurt/Main (Germany),
the Eurofighters broke the sound barrier at about 09:04 (07:04Z)
causing two bangs on the ground.