DCrefugee said
Not my understanding of the public information. ACARS was shut down shortly after feet wet and before Malaysian ATC bid the flight farewell. Shortly after which the transponder(s) was/were disabled.
The SATCOM system, however, continued to function, in a sort of keep-alive mode, but did not pass flight or aircraft data to the satellite(s). It's the last of those recurring signals that Inmarsat has plotted along roughly the 40N arcs.
It is a ACARS transmitted data collection though, from everything I understand
Don't have time right now to search for a better mention, but here is a quick one at least
Modern aircraft can communicate with airline operations bases and sometimes with the headquarters of its manufacturers automatically in order to send maintenance alerts known as ACARS messages. It was this system that sent out the regular ping, which may have lasted for several hours, the sources said.