Australia's maritime safety agency drastically narrowed the search area in the southern Indian Ocean for the missing Malaysia Airlines MH370 jetliner on Tuesday, but said the remote location, high seas and swift currents meant the task remained daunting.
The Australian Maritime Safety Authority (AMSA) shrunk its search field to a 600,000 sq km (230,000 sq mile) corridor, just 3 percent of the estimated 19 million sq km area in the Indian Ocean where the plane could be, based on satellite tracking data.
Still, the revised area is roughly the size of Spain and Portugal combined and will take the Australian-led southern search team several weeks to comb.
"A needle in a haystack remains a good analogy," John Young, general manager of the emergency response division of AMSA, told reporters. "The aircraft could have gone north or south and if it went south, this is AMSA's best estimate of where we should look with the few resources we have at our disposal for such a search."
AMSA said its revision of the search area was based on analysis of satellite data collected from the plane by the United States National Transportation Safety Board (NTSB) it received on Monday.
AMSA then streamlined that data further to account for water movements and changes in weather in the days since Flight MH370 disappeared 10 days ago.
"It's the result of some analysis of the possible movement of the aircraft," Young said. "There are some assumptions built in, including the speed of the aircraft."
The original search area for flight MH370 focused on a wide strip of territory either side of two arcs formed by satellite plots of the aircraft's last known possible position, an area measuring 38 million sq km.
The northern hemisphere search area is along an arc stretching from Malaysia through northern Thailand, Myanmar and China to Kazakhstan. Young said he had no details on whether that search area has been similarly streamlined.
Australia took charge of the "southern vector" of the search for the plane that had 239 people on board on Monday at the request of Malaysian Prime Minister Najib Razak.
The southern Indian Ocean is one of the most remote places in the world and also one of the deepest, posing enormous challenges.
Seas in the search area characterised by by