Checkboard
It would also be no surprise that no radio calls were received, as the pilots wouldn't be wearing radio headsets in HF airspace (you only put them on if you are called over SELCAL, or intend to transmit a position report.)
This is just an example of silly, misinformed posts on this thread. Pilots still listen out even in HF airspace by means of a loudspeaker and making a transmission is as simple as grabbing a hand held mike. They would have been tuned to 123.45 and 121.5 and able to transmit on both at any time.
I am not sure my priority when dealing with a malfunctioning aircraft in these particular airspaces would be communicating with a difficult to reach ATCO. Comms with Atlantico are notoriously poor and they would have been out of range of both SAL and Dakar (VHF), the latter sharing the poor comms status. HF contact with most of these ATC centres is problematic due congestion and various other factors. CPDLC is available now on a trial basis with Dakar, whether it was used, or if it was, whether it was being monitored will be investigated I am sure.
Unless one is sure of what one is writing here why on earth would one bother to post?
This is a sad event - no doubt not caused by one isolated fact.