Originally Posted by
penguin22
FMC route data can get sent to ATC through a mode S transponder.
Those pprune folks talk about it here
ADS and CPDLC - PPRuNe Forums
I've always kept any unofficial waypoints out of Legs 1 just for that reason. I've been told that they can actually see what we have in RTE 2 also
They way ADS-B works (or at least my understanding) is that it will send out the position you just past plus the next three waypoints. Just like a a voice position report plus a little extra info like winds, speed etc. In addition with the capability for the current position to be pinged.
At my previous company, we used to use RTE2 to put in ETPs and ETOPS pts. So, I am pretty sure those cannot be seen.