I know little about IT, but as you say, there MUST be a way that modern aircraft can transmit "burst" transmissions on a regular basis (say every 20min) to home base including ALL the info that would normally be stored on the FDR/CVR?
OK a lot can happen in the 20min between transmissions, but surely a pattern may emerge leading up to a serious incident?
Of course there is a way, 747guru. The technology exists - satcom/phone link. But it would have to be way more frequent that 20 minutes to be useful. Back of the envelope calculation, you're talking a couple of satphone voice calls worth of bandwidth, continuous.
Not an expert, but the cost would be approximately equal to the pilots' salaries for the flight.
If you were going to spend that kind of money to improve safety, is that really the most effective way to do it? What do you really get out of it?
(Standing by to be flamed)