Mcdunav: Should not the possibility of the plane crashing in the Belitung forests be considered?
Start with the known location of loss of comms. Take max possible a/c airspeed, and known fuel reserve to determine the furthest the aircraft could have flown from the LKP, and draw a circle of that radius centre on the LKP. In principle the a/c could have come down "anywhere" in that circle.
Now get as much information from primary radar as possible, and any other credible data source, and narrow down the area within that circle to give a starting area to concentrate the initial searches for the available search resource - if those initial searches fail then widen the search area. Resources are not infinite. Time is important but you have no control over how long the searches will take irrespective of the media clamour for "information". Make sure that you spend your time trying to get results and not wasted on chatting to the media....