RGBROCK1 got it right
Further, there is a way to accomplish this massive data transfer with minimal reliance on satellites, that is to use IP forwarding, packets would be transmitted from aircraft to aircraft until they arrive at the final destination just like the land based internet. Ships or buoys could also assist. Extremely foul weather might impact those signals, however IP has the feature of continuously repeating a packet until it gets through, and in fact the packets could be transmitted after the incident if the transmitter survives.