I've got a few questions, but I'm not a B-777 guy, so they may be irrelevant.
Was the ACARS MEL'd inop? If the engine data is passed via ACARS and the system wasn't working from the get-go, there would be no data transmitted. That's when the crew does manual engine data checks and logs them in the maintenance log book to be checked later. Was this aircraft SATCOM equipped? Was this specific aircraft ETOPS certified - or did it need to be? Was there a fuel system MEL? Has anybody checked the fuel slips? When those fans stop turning and everything turns dark - no electrical or hydraulic - NOTHING gets transmitted. I suspect fuel remaining from the previous flight on this aircraft would have allowed them to fly for about an hour???!!!
Had the crew logged onto CPDLC? In that area, WSJC would have been appropriate, and regardless of the transponder, the aircraft would have been pinged for location data. A change in altitude would/should have been noticed on CPDLC and may have resulted in an electronic query from the appropriate controller. The next sector - VVTS - Ho Chi Minh - would have received the hand-off from WSJC and electronic communications established. On my flight from WMKP-RCTP (Penang-Taipei) three days ago, Ho Chi Minh asked us to log on to CPDLC so they could communicate electronically while in radar contact.
For those not familiar with flying on that part of the planet, long range communications are primitive. HF position reports are on radio frequencies that are shared with India, Singapore, Philippines, and Viet Nam on occasion. That segment was short enough that when Lumpur Control said "radar service terminated, check in with Ho Chi Minh at [xxxxx point], there likely was no radar coverage. NONE. Controllers depend on position reports to do manual plots of our position. This isn't like a U.S. domestic flight where ARTCC knows the location of every aircraft all the time. Based on mach number, time estimates at each compulsory reporting point, the long range controllers can reasonably track us (PTAPTP), and still maintain aircraft separation at about 50 NM.
This should be an eye-opener for every airline on the planet. Countries aren't investing to ensure all this new technology (CPDLC, ADS-B) can be used. We rely on WW II technology radios for 21st century communications in many places when NOT in radar contact.
V/R,
Nakazawa