Investigators still have no idea what happened to Malaysian Airlines MH370, or the 239 people on board.
But the strange pattern of course corrections and communications issues the plane experienced has led some experts to look for clues in a speech made less than a year ago at a security conference in Amsterdam.
At the Hack In The Box conference, in April 2013, security researcher Hugo Teso stood on the stage, took out his phone, and booted up an app.
It was a simple app - one he coded himself.
It was also an app which - he said - could take over a plane.
Teso, a trained commercial pilot and researcher at N.runs AG in Germany, had created Planesploit, an app which in theory made it possible to pour false data into a plane's navigation systems, and use that to deceive pilots -- all from a passenger's seat.
Planesploit was apparently able to exploit two key technologies which control the operation of an airliner: the Automatic Dependent Surveillance-Broadcast (ADS-B), which talks to air traffic controllers, and the Aircraft Communications Addressing and Reporting System, which controls comms between planes. By spoofing these messages, Teso was able to show how a well-equipped passenger could be in effective control of the plane.
The version of Planesploit Teso showed was able to change a plane's route, make it crash or set off alarm systems inside the cockpit.
Luckily, two things stopped Teso's app sending airline companies into a panic.
First, Teso isn't a hacker, he's a researcher who unveiled the hack only after sending the details of how it was achieved to industry bodies, so they could fix the problem.
Second, PlaneSploit wasn't quite as devastating as it appeared.
Following Teso's announcement, American and European air regulators issued a statement claiming that hacking an aircraft in this way was not possible. They pointed out that Teso had only used simulators and not live aircraft to test his app, and said that autopilot systems could always be overridden by pilots.
The FIAA said:
"The hacking technique described during a recent computer security conference does not pose a flight safety concern because it does not work on certified flight hardware. The described technique cannot engage or control the aircraft’s autopilot system using the FMS or prevent a pilot from overriding the autopilot. Therefore, a hacker cannot obtain 'full control of an aircraft' as the technology consultant has claimed."
The other statements can be read here. There is also a full and interesting rebuttal over at the Ask The Pilot blog. Among the points made is that a plane can always be flown without autopilot - meaning that any discrepancies in data sent to the plane by PlaneSploit could be overruled.
What is unclear is the extent to which the underlying holes Planesploit was able to exploit - particularly the ADS-B network - have been fully patched in the intervening 10 months.
As recently as October 2013, Trend Micro - another security firm - were able to demonstrate how by hacking a similar GPS network to ADS-B could be used to manipulate the path of cargo ships from a computer thousands of miles away.
There are also several other ways in which researchers think a plane could be compromised or hacked.
One scenario raised by Sally Leivesley, a former science adviser to Britain’s Home Office, in various newspapers, is that the main computer systems on a jet could be hacked into via the on-board entertainment system.
While this is again still a theory, Leivesley says it is possible that this type of hack could let passengers remotely control almost any aspect of the plane's controls.
“A mobile phone could have been used to do so or a USB stick," she told the Express.
“When the plane is air-side, you can insert a set of commands and codes that may initiate, on signal, a set of processes."
Experts remain unconvinced, however - with most saying that such elaborate high-tech hijackings remain theoretically possible at best.
There is also no evidence so far that any hack of any kind was carried out on MH370 - or that the plane's entertainment system could have provided access into the plane's communication systems. Several airlines have already said their own entertainment networks are not connected to other internal systems.
RMIT Associate Professor Cees Bil told SMH: "Believe this is very far-fetched and with all the regulations, checks and safety systems in place, I don’t believe something as simple as a phone can interfere with the security system."
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