This question already has an answer here:
Why don't airplane include a satellite technology to upload the critical (Voice/Engine etc) data recorded in FDR to satellite. This would be very useful, in case of missing FDR.
Is there any technology/Equipment existing on this issue?
Note: FDR can just to start transmitting the very latest data first followed by old data in sequence before aircraft gets into crashing mode. Probably we do have some specification/limits to determine the aircraft crashing probabilities. Even if FDR is missing from the crash site we will have some limited data(might not be complete data) which got stored after crash trigger.