In order for the tinfoil hat case to work you have to make certain assumptions and ignore certain realities. First, you have to assume something incapacitated the pilots other than a malfunctioning O2 system. It could have been hijackers, except if it were, they were incredibly inept. They made no radio transmissions, they obviously didn't know how to fly the aircraft, and nobody has claimed responsibility for the accident. You would think that if a hijacker was effective enough to kill the crew, he would have a follow on gameplan other than silently orbiting at 35,000 until the aircraft ran out of gas. So you can surmise the pilots were incapacitated by "someone", or you can surmise the pilots were incapacitated by a lack of 02. Since the pilots never communicated a problem of any sort, they may not have been aware they had a problem until it was too late (ie they were unconscious). Since the emergency O2 systems for the cabin and the cockpit are separate, it is not beyond the realm of possibility that the passengers' worked and the pilots' did not. Hence, the aircraft flew on autopilot with nobody at the controls (pilots, terrorists or passengers) until it ran out of fuel and crashed.
Either way, I'm sure the final report will be interesting reading.
Major news now reporting that medical examiner says copilot was alive at time of impact. Seems odd that the depressurization at 35,000 ft would not have been fatal unless his O2 mask was working. If it was working why was he out and why did he not earlier take emergency action or respond to ATC (after 90 minutes)?
Very Strange....