This is the latest chart of the priority search area for Malaysia Airlines flight MH370 prepared for the Australian Transport Safety Bureau.
A survey of the area in the southern Indian Ocean by two ships using multi beam sonar is almost complete and will provide an accurate contour map of the sea bed which in places is up to six kilometres deep.
At the end of September, three ships, the Equator and Discovery owned by contracted search company Fugro Survey Australia, and the Malaysian-contracted vessel GO Phoenix will begin the search that could finally answer the world's biggest aviation mystery.
The ships will each pull side scanning sonor devices known as "towfish" through the water approximately 100 metres above the seabed attached to armour-plated cable about 10 kilometres long using the new charts to maintain the optimum height and avoid newly discovered underwater volcanoes or other geological features.
The acoustic images from the sonar "pings" will then be fed through the fibre optic cable for evaluation at the company's Perth offices. The towfish made by US company EdgeTech has already been used to find a World War ll bomber albeit in shallower water. There is also equipment to "sniff" any evidence of aviation fuel in the water down to a few parts per billion. A video camera and lights can also be used close up if debris is identified by the scanner.
In a first interview, Steve Duffield managing director of Fugro, which has one year to search the 60,000 square kilometre priority zone was upbeat that the technology was up to the job.
"The nature of the work is similar to what we do every day," he said.
"What's interesting about this is the size, the depth and the location that is just a long, long way away from anywhere.
"The safety bureau has designated the search area and if it is within our search area we will find it. The law of averages say we could find it as easily on day one as on day 365."
He said Fugro's contract was only to "search and identify a debris field" and after that had been achieved decisions about what happens to the aircraft would be made elsewhere.
The passenger flight from Kuala Lumpur to Beijing disappeared on 8 March, six months ago next week, with 239 crew and passengers, six of them Australian, all missing.
Safety bureau spokesman Daniel O'Malley said the search was critically reliant on complex, ground-breaking technical analysis of limited communications data and aircraft flight information.
"This analysis will enable us to prioritise our search within a vast area of the Indian Ocean so we can find the missing aircraft," he said. "We need to remember, though, that it took two years to find Air France flight AF447, whose last position was known with much more precision. We're dealing with a much more challenging set of circumstances.
"The arc associated with the seventh communications handshake is the most reliable information we have. We are confident that the aircraft will be found along that arc. Our task is to determine the priorities for searching on that arc. Priority zones for the underwater search are being finalised and ranked. We can then deploy excellent search technology and skilled crews available to us to search those zones thoroughly. All this work will ensure the best prospects of finding the aircraft and solving the mystery of MH370."
Irene Burrows from Brisbane who lost her son Rodney Burrows and his wife Mary on the flight, said she had felt that the search for MH370 had been overtaken by the shooting down of Malaysian flight MH17.
"I felt it had been forgotten and neglected but I had a ring from deputy prime minster [Warren Truss] and he informed me it hadn't and they were doing surveys beneath the water. He said it might take 12 months, it might take two years. He assured me that it will carry on. They assure me they are pretty sure this is where the plane is."
She said she didn't ever envisage there would be bodies from MH370 to bury.
"If they find the plane I just want it left there. Leave everything as it is."
