ChristiaanJ about satellite upload:
The continuous data stream into the FDR includes far, far more parameters, llike attitude (all axes), airspeed, engine parameters, control surface positions, etc., sampled every few seconds, sometimes even more often.
It's way, way beyond what could be transmitted via a satellite link, or stored and managed at the receiving end, for the tens of thousands of commercial flights in the air at any one time.
Agreed. But it is not necessary to stream the full data. Data may be compressed by a method called "delta modulation" whereby only changes of values are transmitted once their base value is established (as in modern video and audio streams). In level flight, compressed FDR data could be reduced to a manageble data stream. Data uploaded this way may not give a precise picture when data changes rapidly (like an FDR) but might still be helpful to establish the sequence of events.