Hilarious that so many of you think the plane was shot down, without a shred of evidence to support your theory.
How many planes are actually shot down?
I prefer to go with Occam's razor on this one: the simplest explanation is that the flight simply had a mechanical failure and crashed. That's what happens in 99.99% of plane crashes, they aren't "shot down."
"But but but.... Peter Grimm..... how come we can't find the plane if it were just a regular mechanical failure?"
Well, you dummies, it's a very very very big ocean, and you're dealing with the Malaysian government, not exactly the Sherlock Holmes' of the world.