The hunt for flight MH370's 'black box'
26 March 2014 Last updated at 21:13 GMT
If a debris field from the wreckage of Malaysia Airlines flight MH370 is found, the challenge of locating the plane's flight recorders can begin.
The so called "black box" could hold information that may help investigators explain why the Boeing 777 crashed in the south Indian Ocean.
Theo Leggett reports.