My Theory
On the 6th March Anwar Ibrahim ex PM of Malaysia is re convicted on a sodomy charge, accepted by the majority of the populace as a trumped up charge to discredit him and keep him out of politics.
Captain of MH370 is a keen political activist as well as an experienced pilot who has constructed his own simulator which would enable him to practice many aviation scenarios.
He is mega pissed off by re conviction of ex PM and decides to make a political statement. What is biggest terrorist offence ever? 9/11 twin towers.
He decides that he is going to fly aircraft into Petronas Twin Towers in KL. So acts normal within Malaysian airspace then turns west intending to go back to KL after disabling communications.
Now gets cold feet, but it's too late he cannot suddenly revert to original flight plan. So continues to fly west out into Indian Ocean where he then flies south into one of the largest open oceans until fuel runs out after a radar trace is spotted by Perth.
Stranger things have happened!
Well its a better theory than some that have been bandied around by the international media!
TBWG