the missing plane. the search largely focused off the western coast of australia. you can see here where they have been looking. how could the debris end up all the way from over here to reunion island? cnn s ander stevens is here on the exhaustive search efforts since the plane vanished. andrew? reporter: who would have thought it would be 500 days when they first find the debris linked to mh370. flight 370 taking off to beijing disappearing shortly after its takeoff. and the search began. and it was an enormous search too, to begin with. if you look at what most people would say the time it must have gone down somewhere on the flight route. but as the information came out that it had doubled back on itself the search area got bigger and bigger. one stage, 4.6 million square kilometers search zone. that s just an enormous area. 26 countries were involved in that search at that stage.