After a four-month hiatus, the hunt for Malaysia Airlines Flight 370 is about to resume in a desolate stretch of the Indian Ocean, with searchers lowering new equipment deep beneath the waves in a bid to finally solve one of the world's most perplexing aviation mysteries.
The GO Phoenix is the first of three ships that will spend up to a year hunting for the wreckage far off Australia's west coast. Crews will use sonar, video cameras and jet fuel sensors to scour the water for any trace of flight MH-370, which disappeared March 8 during a flight from Kuala Lumpur to Beijing with 239 people on board.
The search for the flight, whihc was captained by senior pilot Captain Zaharie Ahmad Shah. has been on hold for months so crews could map the seabed in the search zone, about 1,800 kilometers west of Australia.
The 60,000-square kilometre search area lies along what is known as the ''seventh arc'' - a stretch of ocean where investigators believe the aircraft ran out of fuel and crashed, based largely on an analysis of transmissions between the plane and a satellite.
Given that the hunt has already been peppered with false alarms - from underwater signals wrongly thought to be from the plane's black boxes to possible debris fields that turned out to be trash - officials are keen to temper expectations.
''We're cautiously optimistic; cautious because of all the technical and other challenges we've got, but optimistic because we're confident in the analysis,'' said Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, the agency leading the search. ''But it's just a very big area that we're looking at.''
That area was largely unknown to scientists before the mapping process began in May.
Two ships have been surveying the seabed using on-board multi-beam sonar devices, similar to a fish-finder.
The equipment sends out a series of signals that determine the shape and hardness of the terrain below, allowing officials to create three-dimensional maps of the seabed.
Those maps are crucial to the search effort because the sea floor is riddled with deep crevasses, mountains and volcanoes, which could prove disastrous to the pricey, delicate search equipment being towed 100 metres above the seabed.
Two of the search ships will be using underwater search vessels worth around $1.5m each.
''You can imagine if you're towing a device close to the sea floor, you want to know if you're about to run into a mountain,'' said Stuart Minchin, chief of the environmental geoscience division at Geoscience Australia, which has been analysing the mapping data.