The key point is value for money.
We'd be downloading large amounts of data into the ground distribution systems (only two available) at enormous cost, nearly all of which would be the routine dross that we already collect for free after each successful flight and put into our FOQA and Reliability Analysis programmes. For example, its the cost of ground distribution that already leads many operators to ignore ACARS completely while those that do use ACARS limit the data to just the OOOI and whatever reports they they need for Maintrol/Ops control. Downlinking, in real time, everything that the DFDR records, would be an enormous cost to pay for data that we don't need.
For the very, very rare occasions when an aircraft goes down, unpredictable manouvres that occur during a departure from controlled flight would result in data loss for the actual event. The only time we'd get useful accident data would be for CFIT. That's a lot of money to pay for little return. If its the accident investigators (in other words, government agencies) that want the data, let them pay for the collection and distribution charges.
Last edited by Blacksheep; 25th Jun 2009 at 09:21.