[SystemSafety] Boeing 787 position flaw

[paul_e.bennett at topmail.co.uk]

On 15/12/2015 at 6:20 PM, "Martyn Thomas" <martyn at thomas-associates.co.uk> wrote:
>
>Yes, but Lat/Long would be available together from GPS, so it 
>would be a
>very strange decision to send them separately. Yet only one was 
>missing
>from the data packet, and the transponder software had been 
>designed to
>expect this.
>
>Martyn

It seems strange to me also. Any instrument broadcasting data should
always send all of its packet and expect a NAK if this was not achieved
or successfully received.

In most of my comms I will perform a check on data that is supposed to 
always be changing to ensure it does and may raise a warning if it does
not change as expected. With a transponder reporting position, the non-
receipt of one of the coordinates means it does not have a valid datagram
to send and might be better off not sending anything and issuing a warning 
that it was unable to do so.

Regards

Paul E. Bennett IEng MIET
Systems Engineer

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