Not no information, just nothing but a distance from the receiver. If you have a second receiver, you can see where the two distance radii intersect, and know that the transmitter was at one of those two points. With a third receiver, the radii will intersect at a single point – hence triangulation. That’s why they’re searching an arc – it’s that section of the single observer radius that the plane could have reached with the fuel it had available.
The persistent question is how accurate that distance estimate from the satellite was in the first place. Is there any way it could be so dramatically wrong that the plane really could have proceeded on its path after the turn west to pass over the Maldives, or just hit the water somewhere in the middle of the Indian Ocean, rather than ending up somewhere on an arc that’s way off that path?
