(Bloomberg) — The first boat being used in a resumed deep-seasearch for Malaysian Airline System Bhd. flight 370 has embarkedfor the southern Indian Ocean, as investigators said three zoneswould be a priority.

The Malaysian-contracted GO Phoenix vessel departed fromSingapore Sept. 9 and will receive instructions about its searchzone within days, Martin Dolan, chief commissioner of theAustralian Transport Safety Bureau, said in an interview.

The deep-sea sonar search of the 60,000 square-kilometer (23,000square-mile) zone off the coast of Western Australia is the besthope of finding the remains of the Boeing Co. 777-200, whichdisappeared March 8 with 239 people on board en route from KualaLumpur to Beijing. The only clues to the aircraft's final restingplace have been data exchanges with an Inmarsat Plc satellite,which indicated it ditching somewhere along an arc of ocean west ofPerth.

“We're now at the point where we can say we've pretty much got asequence of priority areas along the arc,” Dolan said in theinterview yesterday. “We know the first place we'll be searchingand we'll be formalizing the tasking for that within the next fewdays.”

The yearlong search to begin later this month will be the secondtime that investigators have sent submersibles down into the deepocean in search of debris from the plane, particularly the flightdata and voice recorders which could help explain itsdisappearance.

Final Resting Place

A search spanning 850 square kilometers in an area where soundssimilar to those of black box emergency beacons were heard by anAustralian search vessel in early April turned up no evidence ofaircraft debris.

That region, in tropical waters to the north of the currentsearch zone, “can now be discounted as the final resting place ofMH370,” the Joint Agency Coordination Centre, an Australiangovernment body working on the search, said May 29.

Survey vessels have spent the past four months carrying out lessdetailed surface surveys of the ocean floor, which incorporatesridges, trenches, undersea mountains, and featureless plains. Thatwill help guide the deep-sea search.

“We can see extinct volcanoes, 2,000-meter cliffs,” Dolansaid.

Heavy Seas

The boat-based scans have found some areas that appear harderthan the surrounding terrain, but “the geoscience professionalshave been saying we're pretty sure they're geological,” hesaid.

Such anomalies can be caused by rocky outcrops amid silt orchanging rock types, Dolan said. It's “highly unlikely” that anywreckage would have disappeared beneath an undersea rockfall, hesaid.

Heavy seas in the region have affected survey work being carriedout by the Fugro Equator, a vessel operated by Leidschendam,Netherlands-based Fugro NV, according to a statement postedyesterday on the ATSB's website.

Fugro won an Australian government tender to carry out the12-month deepwater search and will deploy the Equator and the FugroDiscovery. The GO Phoenix is contracted to the Malaysiangovernment.

ATSB officials are trying to work out how best to deploy thevessels and will send them initially to three different zones,Dolan said. If any zone appears more interesting, two of thevessels could be moved to study it more intensely.

“We've had really good vessels and equipment, and highly skilledcrew,” he said. “If all that comes together I'm cautiouslyoptimistic.”

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