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

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

5