Wawa: been to NG737 school as an avionics tech. No direct hands on in a 777. In general most boxes have 2 different buss inputs. Not so say it couldn't happen, but sems way out there. And you would get error messages on the EICAS.
In retrospect, it the pings included basic lat/long info, just degrees and min. We wouldn't be so lost at this point. And the satcom needs it to point the Antenna anyway. 10 bytes once an hour...
