MAKASSAR, Indonesia (Reuters) - A U.S. navy ship helping hunt for an Indonesian plane missing for nine days should be able to shed more light later on Wednesday on a metal object found on the sea bed, an Indonesian navy commander said.
The search for an Adam Air Boeing 737-400 that vanished in bad weather on Jan. 1 with 102 people aboard has chiefly focused on large metal objects, possibly wreckage, detected on Monday by Indonesian ships using sonar in deep water north of Mamuju in west Sulawesi.
"It will take them until 10 p.m. (1500 GMT) tonight to confirm the exact position and to figure out what kind of object is down there," Moekhlas Sidik, commander of the navy's eastern fleet, said after returning from aboard a ship in the area.
He said that the USNS Mary Sears, an oceanographic survey ship, had confirmed the findings of an Indonesian ship of metal objects at three points and was focusing on one of the sites.
"Mary Sears has multi-beams to receive noise frequency that will enable them to form a silhouette. We are focusing on the coordinate that has the strongest ping," he told a news conference in Makassar, Sulawesi's largest city and where the search is being coordinated.
The spot being examined was 31 km north-west of Tanjung Rengas at a depth of 1,700 metres, he added.
Earlier, First Air Marshal Eddy Suyanto, the Makassar air base commander coordinating the search, said the depth of the objects could present problems for the search.
Mark Jarrett, deputy director of operations for the U.S. Naval Oceanographic Office, said the U.S. vessel conducted oceanographic surveys and can map the sea bed, but had its limits.
"In shallow water that's not too difficult to do, in less than 500 metres. Any deeper ... and it will be very difficult for our ship to identify any parts, especially if they're small," he told Reuters in Washington.
Officials say none of the ships involved in the operation, including two additional Indonesian navy vessels that joined the search, carry submersible vessels capable of reaching the sea bed and examining possible wreckage first hand.
SEARCHES GO ON
Other air, land and sea searches meanwhile continued over, in and around Sulawesi island for the plane that vanished on its way to Manado in the north. But Suyanto said reports on Tuesday of wreckage sightings on land were "negative".
The plane disappeared less than three days after a ferry with more than 600 aboard capsized and sank off Java.
Fourteen people were rescued this week after drifting hundreds of miles on a life raft for nine days, bringing the total number of survivors to at least 248.
Hundreds were still unaccounted for and the Senopati Nusantara ferry had yet to be found, although Tony Syaiful, spokesman for the Indonesian navy's eastern fleet, said two navy ships had been combing the Java Sea north of Central Java province for the past two days.
Their sonar had detected a number of signals but there were "a lot of old ruins and mines from World War Two in the area. Therefore we have to do a thorough investigation," he said.
The areas being searched are about 60 metres deep, allowing divers to check out significant findings, he added.
Planes and six navy vessels kept up the search for survivors and bodies from the ferry.
The twin ferry and air disasters have thrown a spotlight on the poor record of transport safety in Indonesia.
A top transport official was quoted by the Jakarta Post as saying the government would make top management of airlines liable rather than just companies or pilots if they failed to comply with safety regulations.
"An airline's top management can be held responsible for forcing airplanes to fly in a way that compromises flight safety," Air Transportation Director-General M. Ikhsan Tantang was quoted as telling reporters after a meeting with airlines.
(Additional reporting by the U.S. Pentagon bureau and Mita Valina Liem in Jakarta)