Originally Posted by Sallyann1234
continuous transmission of all FDR data from commercial aircraft would far exceed available satellite capacity. And extending that capacity to the extent required would be extremely expensive.
If each DFDR produced 100 parameters at 16 bit resolution at once per sec, that would be 200 bytes per sec per a/c. For 2,500 a/c, that would be 500 kilobytes/sec.
NASA's TDRS satellites are designed for receiving and forwarding telemetry, and have a total bandwidth of about about 1.1 gigabit/sec (137 megabytes/sec). Of this bandwidth handling all parameters from all DFDRs from all in-flight commercial a/c would take about 4% of TDRS capacity.
Obviously the primary use TDRS is for NASA but they accept other special users. I'm not saying continuous telemetry from all large commercial a/c is needed, nor that TDRS is the best way, but it illustrates the raw capacity is already there.