Flight MH370: The technology that tracked missing plane
25 March 2014 Last updated at 18:45 GMT
The route and likely crash site of missing Flight MH370 has been extrapolated from data sent from the plane, despite its tracking systems being turned off.
The Malaysia Airlines plane disappeared on 8 March as it flew from Kuala Lumpur to Beijing, with 239 people on board.
Andy Moore explains how experts have focused the search for the wreckage.