Page 15 - ITU-T Focus Group on Aviation Applications of Cloud Computing for Flight Data Monitoring - Avionics and Aviation Communications Systems
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ITU-T Focus Group on Aviation Applications of Cloud Computing for Flight Data Monitoring
                                            Avionics and Aviation Communications Systems



               recommend that solutions enabling triggered transmission of flight data (TTFD) are employed for aircraft used
               on extended overwater operations (EOO).

               NTSB proposes that "(flight) data should be captured (and transmitted) from a triggering event until the end
               of the flight and for as long as a time period before the triggering event as possible." Performing triggered
               transmission of flight data in this manner introduces a higher bandwidth requirement for an aircraft in distress
               and the bandwidth need increases closer to the end of the flight and the longer the time period before the
               end of the flight. However, with a low number of distress situations, the global bandwidth needs will be a
               fraction of that from continuous routine real-time data streaming.
               An analysis illustrating the data transmission bandwidth performance needs for both continuous routine
               black box streaming and TTFD modes of flight data transmission is provided in Appendix 4. The appendix has
               two sets of tables. The first set of tables describes the global bandwidth need and the global data volumes
               generated if up to 20,000 aircraft were to be simultaneously streaming flight data. Three sets of values are
               provided illustrating the data volumes and bandwidth needs associated with a three-example flight data black
               box recording rates:

               •    Aircraft position data recording only;
               •    64 words per second (wps) standard flight data recording (circa 1995 common standard);

               •    1024 words per second standard flight data recording (circa 2015 common standard).



                   Flight data recorder   Aircraft position only    64 wps FDR           1024 wps FDR
                     (FDR) standard
                Bandwidth needed for   72 bps per (1) aircraft  768 bps per (1) aircraft  12.3 kbps per (1) aircraft
                routine continuous FDR
                streaming

                Global bandwidth needed  690 kbps for 10,000 aircraft 7.32 Mbps for 10,000 aircraft 117 Mbps for 10,000
                                                                                     aircraft

                Global FDR             130 GB                1.4 TB                  22 TB
                data volume            per month for 10,000   per month for 10,000 aircraft per month for 10,000
                                       aircraft                                      aircraft


               The 1024 wps FDR bandwidth analysis is really a worst case analysis and the overall global bandwidth needs
               are likely to be significantly less than illustrated. This is because the analysis assumes no data compression
               is achieved and the FDR standards and actual data volumes are expected to be much less on most aircraft in
               service. While many newer aircraft record flight data at the 1024 wps standard, the most common standards
               in use are 256 wps or less for narrow body aircraft and 512 wps or less for wide body aircraft.

               Appendix 4 provides various TTFD analysis illustrating how many hours of flight data could be transmitted
               through 432 kbps bandwidth based on a triggering event occurring at various times from 1 to 15 minutes prior
               to the end of the flight. Calculations are provided for 1024 wps, 512 wps, 256 wps and 64 wps FDR standards
               and some extracted results of how much accumulated data could be streamed are shown below:
                                                               Time of triggering event
                      FDR standard             2 minutes             5 minutes            10 minutes
                                           before end of flight  before end of flight  before end of flight
                        1024 wps             1 flight hour of        2 hours of            5 hours of
                                               data sent             data sent             data sent








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