this aircraft was disabled in three primary systems.
I presume this statement refers to VHF voice, ACARS and the SSR transponder.
I remember hearing a statement by a Malaysian official in an early presser that one or more of these had been disabled. However, I don't recall ever seeing an explanation of how the investigators
know that these systems were deliberately disabled by human intervention (which is the interpretation constantly assumed here and elsewhere, not least in what I've seen of Tim Clarke's remarks), as opposed to transmissions from them simply ceasing to be received past a certain time, for reasons unknown.
Could someone enlighten me? Were logoff or shutdown messages received from some source? I haven't seen reference to such in the disclosed ACARS information, and I didn't think that audio transceivers and SSR transponders did such things.