Well according to my 777 FCOM 1 and FCOM2
"ADS-B is a broadcast surveillance application that uses Enhanced Mode S
transponder capability to transmit aircraft parameters such as flight number, postion integrity and pressure altitude...."
ergo it's not going to provide ATC with info outside ground based radar range.
However ADS-C does "allows position reporting using the ADS feature of FANS I/A equiped aircraft as an alternative to voice communication position reporting...."
So unless the transponder Mode-S related data is relayed via Satcom you are ADS-C only (and hopefully, but not necessarily, CPDLC
) when Oceanic... so I stand by my previous post ...for now
