specific portion of the southern corridor off the australian coast. but that search area is still massive. cnn's tom foreman is standing by for us in our virtual room. and tom, i mean, good news that they're narrowing it. bad news that it's still so huge. >> yeah, this has been this way the whole time. like a step forward and then you realize it's still two steps back because it is huge. this is massive. this is the latest search area that they're focusing on. bear in mind, they're still considering the bigger area. but the focus is right here. what we're talking about is 621,000 square miles. that's five times as big as the air france search area, where it took two years to find the plane. so why is it still so big? let's look at the dynamics of this plane and that will give you an idea why. the first thing you have to think about in all this is speed. speed. how fast was this plane going? they have an idea. they have a pretty good guess as to how fast it was going. but a pretty good guess still