Malaysia Airlines Flight MH370 Puzzler: Why Did SatCom Switch On After Communications Shut Off?

As the search for Malaysia Airlines Flight MH370, which vanished without a trace on March 8 of last year, appears to be hitting a dead end, independent investigators say they’ve found a possible solution to one of the strangest mysteries of the missing flight’s final hours.

Even with all communications systems on the Boeing 777 shut down, the satellite communication system suddenly switched back on.

But how? Could the weird reappearance of a single communication device have resulted from an explainable technical glitch? Or did some person on board turn the system back on — for reasons unknown?

Members of The Independent Group, a loosely affiliated network of aviation and technical experts who have been conducting their own inquiry into how the Malaysia Airlines plane could have simply disappeared seemingly into thin air for the past 10 months.

Now, a new report from a member of The Independent Group says that the most likely explanation for the baffling reappearance of the satellite system — known as AES, or Aircraft Earth Stations — was that someone or something turned the power to the system off, then back on again.

Less than an hour after the Beijing-bound Flight MH370 took off from Kuala Lumpur, all of the plane’s communications systems suddenly shut down, including voice communication systems and the plane’s radar transponder, as well as the satellite system, primarily used to allow phone calls to be made from the plane, or for text messages to be sent.

The AES on board the Malaysia Airlines plane also received so-called “handshake” messages from a satellite run by the British firm Inmarsat. Sent every hour, these “handshakes” simply allow the plane to automatically tell the satellite, “I’m still flying.”

After the satellite systems were silent for about 50 minutes, they suddenly and mysteriously started working again, and continued working for about six more hours — even though there were no phone calls or text messages transmitted from the plane during that time.

When the AES switched back on it spent about three minutes sending a series of signals to the Inmarsat satellite. Australian investigators concluded that those signals were part of an automatic log-on process that happens when power to the system is turned off then flipped back on again.

Largely because those signals point strongly to a deliberate restart of the system, independent investigator Mike Exner, in a recent guest post on the blog of fellow independent investigator Jeff Wise, ruled out other causes for why the Flight MH370 system could have lost communication with the satellite, such as atmospheric electrical interference, or the possibility that the plane was in a geographic location where linking with the satellite was impossible.

No investigator has yet come up with a good explanation of why the satellite system power was switched off and on — or who might have done it. Some independent investigators believe the weird anomaly is evidence that Malaysia Airlines Flight MH370 was the victim of a highly sophisticated, high-tech hijack.

The mystery also creates another puzzle. If some person switched the system back on, why not also switch on the other communications systems at the same time?

“Only answer I can come up with is that comms were not used because those in control of (Malaysia Airlines Flight MH370) didn’t want to use them,” Wise wrote in a Twitter post.