Yep. Basically you're capturing signals that are being broadcasted continuously and interpreting them to locate where you are. There is no communication between the two.
If someone had a sat phone on the other hand... But who knows if anyone on the plane really knew what was going on? Based on some of the crazy turns/altitude drops I'm sure they knew something was up. In the event of a suicidal captain, he could of said it was a problem, keep calm, everything's fine. Hell even hijackers could say that.