Originally Posted by
FIRESYSOK
I'd suspect, perhaps incorrectly, that a 777-200ER with an airline like MAS would more than likely be kitted with SATCOM.
Just because the airframe in question did not have a particular SATCOM antenna subject to an AD does not mean it didn't have one period.
I would also think the comm system would have to be "logged on" to ensure it was operational on demand.
How would an international airline maintain 'operational control' without SATCOM? VHF/HF voice-data only? Unlikely.
The best I could figure out, 777 has separate locations for SATCOM low-gain and high-gain antennas. MH370 did not have a high-gain antenna, which is why it was not subject to the "fuselage cracking" AD, but it could still have a low-gain antenna for the ultra-low-bandwidth Inmarsat Aero L protocol. It's totally possible that Inmarsat Aero L would involve exchanging periodic standby messages "in background", without anyone noticing. But this is all total speculation at this point and I can't find any concrete data on the exact hardware MH370 had onboard, or on the satellite protocol (that would most likely be proprietary anyway.)