system
A chat on 4chan
human
Pieces of it washed up on the beaches of Madagascar. So it crashed into the Indian Ocean somewhere, which is way off the intended flight path obviously.

Couldn’t have been a terrorist attempt, it was nowhere near any populated region. 

I heard an interesting theory that there could have been some sort of oxygen or carbon dioxide leak in the air supply or something, and all the passengers and staff slowly fell asleep (or died) as the plane was on auto pilot. And then it just crashed into the ocean when it ran out of fuel. 

Kind of creepy to picture a 747 flying around by itself for hours with a whole cabin and crew of dead people.
gpt
The problem is that there's so little in terms of pieces that have been found, it would make more sense that an explosion or fire occurred