They dont know where the hell to search, and the best guesses have not come up with anything. They have tweaked their flight models and come up with areas to search hundreds of miles from each other. ( model is inherently chaotic, a bit like a weather model )
currently they are scratching their heads over the lack of any flotsam being washed up anywhere....which they now way is Very Odd Indeed
Oz is picking up the bill which will easily exceed £100m
Nobody knows the area in which it disappeared. It could be up there, down there, over there. In this ocean, in that sea, blah blah blah. How can such a sophisticated large piece of equipment just disappear? Somebody, somewhere saw so/heard something.... yet, nothing !