Narrative:

Approximately 30 miles prior to savry intersection in gander oceanic airspace I wondered why we had not received a VHF frequency assignment via cpdlc as we normally due by that point. First officer (first officer) selected the ATC button on the FMS and it showed no active control center next to the R4 button. It was also displaying login empty boxes at L1 and send at the R1 key. I knew this meant we were no longer in cpdlc communication with gander oceanic. I then tried to reestablish communication with gander via cpdlc and after entering their address in the login boxes it was accepted. However it never changed to act center at the R4 key. By then we were crossing savry and I suggested first officer to do an HF position report and query ATC about the receipt of the previous position reports. When first officer established two-way communication with gander domestic we were told to switch to the gander domestic controller on VHF. They did not take our position report and said nothing about the cpdlc issue. We made the switch and were told to login to gander domestic cpdlc. We did this successfully and the gander domestic address showed up under the act center prompt. The flight continued normally and automatic switch of cpdlc active control continued throughout canadian airspace. I have no idea how long we were not connected to cpdlc and if gander had received all or none of our automatic position reports. There were various ways for gander to contact us while in their airspace i.e. Sel-cal; satphone; air-to-air VHF; and guard VHF if they did not receive position reports via cpdlc as they have done in the past. This leads me to believe this failure occurred just prior to savry and may have had to do with a problem in the automatic switching of active control centers.

Related reports:

Google
 

Original NASA ASRS Text

Title: International flight crew reported they had temporarily lost Controller Pilot Data Link Communications (CPDLC) contact with the controlling agency. They were unsure if the automated position reports had been sent during the period.

Narrative: Approximately 30 miles prior to SAVRY intersection in Gander Oceanic airspace I wondered why we had not received a VHF frequency assignment via CPDLC as we normally due by that point. First Officer (FO) selected the ATC button on the FMS and it showed no active control center next to the R4 button. It was also displaying LOGIN Empty boxes at L1 and SEND at the R1 key. I knew this meant we were no longer in CPDLC communication with Gander Oceanic. I then tried to reestablish communication with GANDER via CPDLC and after entering their address in the LOGIN boxes it was ACCEPTED. However it never changed to ACT CTR at the R4 key. By then we were crossing SAVRY and I suggested FO to do an HF position report and query ATC about the receipt of the previous position reports. When FO established two-way communication with Gander domestic we were told to switch to the Gander Domestic controller on VHF. They did not take our position report and said nothing about the CPDLC issue. We made the switch and were told to LOGIN to Gander Domestic CPDLC. We did this successfully and the Gander Domestic address showed up under the ACT CTR prompt. The flight continued normally and automatic switch of CPDLC active control continued throughout Canadian airspace. I have no idea how long we were not connected to CPDLC and if Gander had received all or none of our automatic position reports. There were various ways for Gander to contact us while in their airspace i.e. SEL-CAL; SATPHONE; Air-to-Air VHF; and Guard VHF if they did not receive position reports via CPDLC as they have done in the past. This leads me to believe this failure occurred just prior to SAVRY and may have had to do with a problem in the automatic switching of active control centers.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.