CVR/FDR dumps
Real-time data streaming for all flights seems a bit ott. The question, then, is when to stream? High priority ecam messages, distress squawks and manual triggers (stand-alone and linked to actions such as arming fire bottles) would be possible trigger points. Probably as good as any, really. Like any other system, it has to be possible to power down the satcom in case of fire or fault, and a well-read hijacker would know to do this, but it would be potentially life-saving if engineering people at home or at Boeing could see just what was happening.