One year ago this Sunday, Malaysia Airlines Flight 370 disappeared into the night. Since then, what at first seemed a rare and tragic incident has come to seem something stranger -- a mystery so baffling, so riddled with contradictory evidence, that officials are beginning to wonder if they have been looking in the right place. "If the plane is not found we will have to evaluate the figures and rely on the experts to guide us on what to do next," Malaysian transport minister Da-tuk Ser Liow Tiong Lai told the New Straits Times Friday. But as the world looks back and takes stock, many are overlooking what may be the most significant clue of all, a subtle and easy-to-overlook detail of the flight's communication logs upon which the whole case may hinge.
To understand why this piece of evidence may be so crucial, it's first necessary to establish the context. Forty minutes after MH370 departed from Kuala Lumpur en route to Beijing, at 12.41am local time, the flight crew prepared to leave one air-traffic control zone and enter the next. "Good night, Malaysia 370," they radioed to controllers in Kuala Lumpur. Within minutes, they should have called into controllers ahead of them, in Vietnam. Instead, the plane went electronically dark. The transponder and ADS-B system, which allow the plane to be seen on air traffic control screens, were shut off. The radios fell silent. Soon after, the plane pulled a 180-degree turn and headed back over the Malay Peninsula, then turned again and headed northwest up the Malacca Strait.
The only reason we know this is that, while the plane was no longer emitting any electronic signals, it was still visible to military radar, which actively "paints" targets with beams of electro-magnetic energy the way a flashlight illuminates an object. Radar only works up to a certain distance, however, and over the Andaman Sea the plane slipped out of range.
At this point, MH370 was completely invisible to anyone on the ground. It could have gone anywhere in the world and no one would have been the wiser. But that's not what happened. Instead, three minutes after the plane disappeared from military radar, at 2.25am, the plane sent an electronic signal to an Inmarsat communications satellite. Over the course of the next six hours, the plane would send six more such pings. These would constitute the only evidence of what happened to the plane, and though slim, would allow scientists using novel mathematical techniques to roughly determine where the plane must have gone.
Why did the plane emit these signals? Now we're getting closer to the core enigma. It's a little-known feature of the Inmarsat satellite communications system that if a customer doesn't use it for a certain amount of time -- doesn't send any messages or make any phone calls -- then the Inmarsat satellite will transmit a signal asking that user if he or she is still logged on. The reason the system does this is so that it doesn't have to waste processing power keeping track of ships or planes that have moved out of range or arrived at their destination and shut down. As MH370 moved through the night, whoever was in control of it didn't use the Inmarsat system. They didn't make any calls or send any texts, and when three incoming phone calls were patched through, they didn't answer. And so after every hour of inactivity Inmarsat sent a message of enquiry -- "are you still there?" -- to which the system electronically squawked back, "Yes, still here."
A reasonable assumption would be that whoever took over the plane didn't know about these hourly check-ins, or didn't care. After all, the precise details of how the Inmarsat satellite communications system works are arcane, and Inmarsat hadn't even yet worked out the maths that would allow them to use the signals to track the plane. So Occam's Razor would suggest that when the other communications systems were turned off, this one was left on out of carelessness or ignorance. Many in the media still seem to think that this is the case. On Friday the Australian Associated Press ran an article about the theory that the plane's captain, Zaharie Ahmad Shah, had absconded with the plane as part of an elaborate suicide plot. The story quoted aviation analyst Neil Hansford as saying: "Captain Zaharie probably waited until the co-pilot left the cockpit, then turned off communication systems but didn't realise hourly satellite "handshakes" were still transmitting as he executed his plan."
That's incorrect, however. Whoever was in charge of the plane didn't leave the satellite system on. It was turned off or in some other way compromised. What happened at 2.25am was that MH370 logged back on to the Inmarsat system. I count this as the central, crucial clue for the simple reason that turning the satellite communication system off and on is something that few airline pilots know how to do. And it's not easy to accomplish. For the log-on to have occurred, someone had to either turn off half the electrical system of the plane or else climbed into the electronics bay and tampered with the power or data line feeding the satellite communication system.
This small, easy-to-overlook piece of data, then, has some fairly jaw-dropping implications. It suggests that whoever took MH370 was technically very savvy. And it suggests that the Inmarsat data, the only clue that we have about the plane's final six hours, was not immune from tampering.
I explore some of the possible ramifications in my Kindle Single, The Plane That Wasn't There: Why We Haven't Found MH370. My main hypothesis -- that hijackers turned on the SDU in order to create the false impression that the plane was heading into the southern Indian Ocean, when in fact they were taking it north -- is not the only possible way to explain the puzzling satellite log-on. Indeed, the entire scenario I describe might well be totally wrong. But regardless, in the future any serious attempt to explain MH370 should attempt to account for this crucial fact. Someone tampered with the satellite communication system, and the data derived from it is not unimpeachable.