Long post - bring a sandwich.
Recently schooled by a Hughes SATCOM guru, I learned 'streaming' DFDR and CVR data over satellite link may sound easy, but in fact is not. There are several reasons for this, but two principal issues are bandwidth and available connections.
Cost - directly connected to bandwidth usage and number of stations. Most providers bill by the amount of data and the number of stations or links, ie aircraft. Current SATCOM internet and communication links are subsidized by passenger payments.
In contrast, access to VHF & HF networks, outside of minimal user fees and taxes, is virtually free. Data forwarding is where most of the operating cost for ACARS connectivity comes in using ground-based communication networks and this cost is a single-digit percentage of a comparable SATCOM data rate.
Availability - Spanning several factors, one of which by design allows only a limited number of transponders per satellite. A common satellite band used in North America currently runs at around 75% capacity. Those limited channels and bandwidth would quickly overload should the world's major airlines suddenly start uplinking data from a pool of the 100,000 odd EDIT: commercial flights that typically ply the skies each day.
Build more birds? The cost of a typical Comms Satellite is around $500 million US and obtaining a Geosynchronous parking slot for just one bird typically takes several years of waiting in a queue.
Someone would need to pay for not only the bandwidth once available but also the expansion of existing systems to accommodate. Without subsidization support of passengers or governments, it is doubtful many airlines would be willing to cut into their already tight budgets for this.
You might ask the question, "Wouldn't passengers be willing to pay for the unseen and unfelt benefit of a DFDR/CVR 'streaming' mandate?" Unfortunately, it has been several decades since safety was a marketable commodity in commercial aviation, so I would say, no.
Last edited by vapilot2004; 6th Jun 2016 at 09:58.
Reason: Cap Bloggs took issue with my obtuse statistic. Corrected!