A plausible theory why they have not found Malaysian Airlines Flight MH370 is that they are looking in the wrong place. Apart from this the underlying assumptions on how it disappeared and the possibilities on why it has disappeared are not yet complete.
Many theories now abound as to what caused it to disappear. Many speculate that it has crashed due to pilot error. Some have even put forth the theory that the pilot committed suicide and planned the whole thing all along. Some have attributed the disappearance to aliens and circumstances approaching that of the Bermuda Triangle and triangle theory of magnetic fields scattered across the world. Yet some have also looked at the possibility of it being hijacked.
The last, though details are somewhat sketchy and lacking, seems to be the most plausible. Two guys get on the plane with fake passports, for whatever reason is strange enough. Would not immigration authorities notice this at the point of embarkation? That definitely restores my faith in airline security in an Asian country.
But if it was hijacked where would it go? As the assumptions center around it crashing around the sea, everybody is looking in that area. However I do posit the possibility that it is very much intact and somewhere near Vietnam, on land, and most probably safe and sound (for the passengers it may be another story altogether).
If one remembers history, this area is quite near the Golden Triangle. The Golden Triangle is an area quite notorious for drug smuggling and opium runs since the days of the Cold War and heavily funded by the CIA. Perhaps we should start on this possibility. The reason is that there is the possibility of several secret if not abandoned airfields within Vietnam and its neighbors that have been used by the clandestine operations of Air America in the past. Could it not be possible that the plane be on one of these fields, whether it was caused by hijack or even some other notorious reason?
In any case, it is a possibility. We are looking in the wrong place. And I will bet my last dollar that the plane is not at sea at all, but somewhere on land.