MH370: Search team 'cautiously optimistic'

This weekend will mark a year since the Malaysian Airliner MH370 disappeared soon after take off on route from Kuala Lumpur to Beijing.

There were 239 people on board. Twelve months on, the plane's fate remains one of the world's great mysteries.

The underwater search is focused in an area of the southern Indian Ocean around 1,800km (1,120 miles) off the coast of western Australia.

Martin Dolan is chief commissioner of the Australian Transport Safety Bureau which is leading the search.