The WSJ reports:
Aviation investigators and national security officials believe the plane flew for a total of five hours, based on data automatically downloaded and sent to the ground from the Boeing Co. 777’s engines as part of a routine maintenance and monitoring program.
If that is the case then the search area is vast.
The bottom line is that nobody really knows where the plane is and the demands of a 24/7 news cycle are exacerbating the situation. Much of the criticism of the Malaysian authorities is somewhat unfair – nobody can know what happened until the plane is found. In the meantime all we can really know is that the passengers and crew are dead.