We Have Been Informed

• Flight YYY777 sent a Controller Pilot Data Link Communications (CPDLC) logon request using incorrect aircraft identification YYY772.
• Flight plan having the aircraft identification YYY772 was already active in the ATC flight data processing system. This aircraft was not logged on with the ATS system.
• Consequently the logon request was automatically accepted by the ATS system and automatically associated with the flight plan of YYY772.
• Therefore the uplinked ATC clearances intended for YYY772 were actually received by YYY777.
• Voice readback of the CPDLC instructions and other communications with the aircraft involved, triggered the recognition of the miss-match and the situation was clarified and resolved on the voice frequency.
• When queried as to whether they received the CPDLC messages, the crew of YYY772 did not highlight the fact that they were not CPDLC connected at the time.