The next phase of the search for missing Flight 370 is shifting south along the "seventh arc" in a vast area of the Indian Ocean — an effort that could take more than a year, Australian officials said Thursday.
Australian Deputy Prime Minister Warren Truss told reporters in Canberra that this phase will be in two parts: an effort to map nearly 60,000 square kilometers (about 23,000 square miles), expected to take about three months, and then the search itself, which he said was expected to take 12 months.
Sign up for breaking news alerts from NBC News
"This area of the sea is very deep, three to five kilometers (1.9 to 3 miles), and it is largely unmapped," Truss said.
He said the scope of the effort was daunting. He noted that the previous effort that searched the sea floor nearer to Australia covered just 860 square miles.
Nevertheless, he said, "Australia remains committed to solving this, the greatest aviation mystery in history."
Truss said two ships, Chinese survey ship Zhu Kezhen and the Australian-contracted vessel Fugro Equator, began the mapping earlier this month. He said it was expected to last into August, when the search would begin.
Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, also revealed that authorities were "confident that the aircraft was operating on autopilot until it ran out of fuel."
The search began when the jet, carrying 239 passengers and crew, lost contact with air traffic control after it took off from Kuala Lumpur headed for Beijing on March 8.
After nothing was found off the coast of Vietnam, or the other direction in the Andaman Sea or the Bay of Bengal, the Australian government agreed on March 17 to lead searches in part of the Indian Ocean south of Sumatra, about 2,000 miles southwest of the Australian port city of Perth.
On March 28, authorities reassessed their calculations based on better estimates of radar tracks, satellite data and available fuel and moved the search northeast almost 700 miles closer to Perth.
The Bluefin-21, a U.S. Navy robotic submarine, was sent to follow a series of "pings" that authorities thought could have been picked up from the jet's black box data transmitters. That effort was declared a bust May 28.
The "seventh arc" is the jet's likely position based on its final hourly transmission, or "handshake," with a satellite.