A US Navy survey ship has joined the search for an Indonesian plane which went missing nine days ago.
The search involves thousands of soldiers, police and civilians
Oceanographic equipment is being used to determine whether metal objects found off the west coast of Sulawesi are from the wreckage of the airliner.
But because of the depth at which the objects were found, experts admit they face a difficult task.
The Adam Air Boeing 737-400 disappeared from radar screens last Monday, carrying 102 people.
It had been flying from Java to the northern Sulawesi town of Manado, and while the pilot had been forced to reroute several times due to bad weather, he did not report any technical difficulties.
A massive air, land and sea operation has been under way ever since the plane went missing, with several other countries offering to help in the search.
Bad weather has hampered the hunt, as have false leads. Government officials had to apologise soon after the plane's disappearance for erroneously saying that the wreckage had been found.
Since Monday, the search has focused off the coast of western Sulawesi, on the advice of a local fisherman, who reported seen a low-flying, unstable plane in the area.
An Indonesian vessel then reported detecting large pieces of metal on the seabed, and the US Navy ship Mary Sears was called in, because of its specialist sonar and satellite imagery equipment.
"The (USNS) Mary Sears has a multi-signal device. It can receive a lot of signals at one time so that it can figure out the silhouette of the objects," said First Air Marshal Eddy Suyanto, the Indonesian air base commander co-ordinating the search.
But he told Reuters news agency that the depth of the objects - about 1,000m (1,150 yards) - might present problems.
Meanwhile other air, land and sea searches are continuing around Sulawesi, but no other sightings have been recorded.