Missing plane: Sonar kit in search for flight MH370
27 March 2014 Last updated at 16:37 GMT
The search for missing Malaysia Airlines flight MH370 is continuing in the southern Indian Ocean.
Satellites have detected some 300 objects across an area of about 1,680 miles (2,700km) and planes and boats have been sent to try to find and recover them.
If proven to be debris from the plane - which Malaysian authorities say crashed with no survivors in this remote area of ocean - the next stage would be to try to recover the aeroplane's "black box" recorders.
The BBC's Richard Westcott went to see the sonar equipment that is likely to be used in the search.