Planes are being steadily equipped with the facility to use mobiles (oddly enough I was on a BA flight on the day of the playoff second leg last year grrr bloody work etc and was getting updates by txt over the Atlantic), but I doubt this one was. If there was smoke or loss of oxygen at even...
Think this article points to some of the most likely explanations so far IMHO, but who knows. Hijack or deliberate pilot action, turn of the comms devices, attempt to fly somewhere and crash, either deliberately (unlikely perhaps as if you had an agenda you'd want the world to know ?) or...
Desperate for the families involved. Doesn't appear to be a lot of official news available yet other than it's missing. B777 safety record is astonishingly good (no fatalities in 20 years until San Fran incident last year where 3 died).