Interesting statement from John Goglia, a former member of the National Transportation Safety Board, that the ACARs system was the source of the pings sent by SATCOM (not the SATCOM system itself as previously speculated).
Thus, the ACARS transmitter continued to send out blips that were recorded by the Inmarsat satellite once an hour for four to five hours after the transponder was turned off
MISSING MH370: 3 pieces of evidence point to jet's takeover - Latest - New Straits Times