The commander of the Royal Navy ship searching for flight MH370 has told Sky News they are getting close to sending down a mini-submarine to hunt for wreckage.
HMS Echo is working with Australian vessel Ocean Shield to locate the Boeing 777-200's black box before it runs out of power.
The plane carrying 239 people vanished from radar on March 8 and is thought to have crashed in the southern Indian Ocean, around 1,500 miles off Australia's west coast.
Ocean Shield, towing a US Navy device to detect signals from the plane's fading beacons, first picked up two underwater "pings" consistent with those from a black box on April 5.
This was followed by two more in the same area three days later.
HMS Echo is searching the southern Indian Ocean for the missing jetThe crew of HMS Echo are analysing the signals by looking at the currents and ocean depth of around 2.8 miles (4.5km) to try to pin-point the plane's wreckage.
The underwater search zone has been narrowed to around 500 square miles (1,300 square km) - roughly the size of Los Angeles.
Phillip Newell, commanding officer of HMS Echo, told Sky News: "We believe we have come close to that point now where we can move to the next stage and deploy a remote vehicle which can go down to the correct depth and search the sea bed."
The Bluefin-21 can search between 20 and 40 square miles a dayThe crew will use Bluefin-21, a mini-submarine used to find the Air France plane that crashed into the Atlantic in 2009, to search the sea bed for debris.
But major hindrances still remain, and it could be years before the Malaysia Airlines jet is found, radar expert Professor David Stupples told Sky News.
The search is also set to be hampered by bad weather this week.
Sunday's planned search areaEleven military aircraft, one civil aircraft and 14 ships are taking part in today's search, said the Joint Agency Coordination Centre, the international body leading the hunt.
It said there have been no confirmed acoustic detections over the past 24 hours.
The batteries that power signals from the plane's flight data and cockpit voice recorders last only about a month and it has been more than five weeks since the plane disappeared.