Originally Posted by
sandos
Couldn't CPDLC logging-on be made automatically? In my mind such a system becomes much more useful, specifically as a side-channel for lost comms, if the pilots didn't need to do anything except maybe once at the start of the flight (entering a callsign/ID/authentication, whatever), and it then handles log-ons by itself. I realize this might be difficult for technical and legal reason, such as it not being easy from GPS position to determine where to log in....
Once the ATN-B2 system is operating on VDL2 initial CPDLC logon will be automatic. The current controller is known as the 'Current Data Authority' and on handover the controller's system initiates a 'Next Data Authority' message identifying the next controller's CPDLC identity to the aircraft systems which then will transfer the CPDLC connection to the next controller.
Problem is that CPDLC is rather like sending an SMS text message from your cell phone. You do not know that it has been read by the crew until/unless you get a response.