PositiveCynic
Now surely instinct these days is to grab for your mobile first - maybe even video the event! So it just appears odd that there is not a single piece of mobile transmission evidence appearing. A "ghost" plane with the pilots knocked out behind a security door run on autopilot would surely have every device owned by anyone still conscious at back on speed dial. Even in a hypoxia situation, then surely at least one phone would have been switched on by someone in distress and stayed on for the remaining time of flight.
The fact that they may have been over the sea and from what I understand there aren't to many floating cell phone masts in the middle of the ocean
might explain the lack of social media events at the time.
As for your statement regarding hypoxia, read about the subject first it might give you an understanding why they couldn't turn on a phone let alone use it.