assumptions regarding auto pilot speed. the analysis arrived at a path of flight which was peer reviewed by britain's air safety agency. the air accidents investigation branch. before being submitted to malaysian authorities yesterday. >> this is the first time we've ever been asked to try to find something with just a single signal once an hour. really a great tribute to our scientific team they managed to achieve this. in very simple terms, we have used the difference in speech in which the signal has come from the aircraft to the fixed point, the satellite in space. it's called doppler effect. if you can imagine a train whistle getting loud as it comes toward you and getting more faint as it goes away from you. what we discovered is the southern route is the best fit. >> inmarsat was able to rule out the previously reported possible northern path of the plane and also to determine that the plane continued at more or less the same speed and same direction for the last hours of the flight. since the plane was sending one signal per hour, the company cannot know exactly where the plane's flight ended.