In yesterday’s post I argued that the reboot of MH370’s satellite communications system at 18:25 is a key piece of evidence about what happened to the missing plane. In fact, I would go so far as to say that we should discount any scenario which cannot explain the reboot.
That being the case, I thought it would be a good idea to clarify what we do know about rebooting the satcom and discuss the implications. Right up front I’d like to emphasize that I am by no means an electronics expert and I welcome any corrections or clarifications.
First, some basic background for those who might be new to the discussion. Flight MH370 took off from Kuala Lumpur International airport at 16:42 UTC on 3/7/14 bound for Beijing. At 17:07:29, the plane sent an ACARS report via its satcom. At 17:20:36, five seconds after passing waypoint IGARI and a minute after the last radio transmission, the transponder shut off. For the next hour, MH370 was electronically dark. The next ACARS transmission, scheduled for 17:37, did not take place. At 18:03 Inmarsat attempted to forward an ACARS text message and received no response, suggesting that the satcom system was turned off or otherwise out of service. At 18:22, MH370 vanished from primary radar coverage over the Malacca Strait. Three minutes later—about the amount of time it takes the Satellite Data Unit (SDU) to reboot—the satcom system connected with Inmarsat satellite 3F-1 over the Indian Ocean and inititated a logon at 18:25:27.
The question is, by what mechanisms could MH370’s satcom have become inactive, then active again?



