Why evidence points to Flight 370 Indian Ocean crash

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An aircraft communicates with ground stations via satellite. If the ground station does not receive a signal, it relays a ‘ping’ to the aircraft.


The plane responds automatically with a short message indicating it is logged on. This is known as a ‘handshake.’


The time it takes the signal to reach the ground station can be used to calculate the distance between the aircraft and satellite. This information was used to generate two arcs of possible positions for the errant flight.


British satellite company Inmarsat examined small differences in the expected frequency of the plane’s signal and the frequency actually measured by the ground station. This “Doppler shift” phenomenon enabled it to calculate the speed and direction of the plane.


Analysts plotted the six handshakes and the shifts in signal frequency. They compared how well these matched flights headed north or south. The data matched the southern route.


A new analysis showed that the plane would have run out of fuel sooner than originally thought, shifting the search arc closer to Australia’s western coast.