Countries around Asia have stepped up the search for AirAsia flight QZ8501 that is presumed to have crashed in shallow waters off the Indonesian coast.
Soelistyo, head of Indonesia's search and rescue agency, told local television the search area between the islands of Sumatra and Borneo would be expanded. Authorities would also begin scouring nearby islands as well as coastal land on Indonesia's side of Borneo.
So far the focus of the search has been the Java Sea.
There have been no confirmed signs of wreckage from the Airbus A320 operated by Indonesia AirAsia, which disappeared in poor weather on Sunday morning during a flight from the Indonesian city of Surabaya to Singapore.
The missing plane, which was carrying mainly Indonesians, could be at the bottom of the sea, Soelistyo said on Monday.
The Java Sea is relatively shallow, making it easier to spot wreckage in the water, say oceanographers, but strong currents and winds in the area mean any debris would be drifting up to 50 km (31 miles) a day east, away from the impact zone.
"The lesson that should be learned from MH370 is that you need to move quickly," said Charitha Pattiaratchi, an oceanographer at the University of Western Australia, referring to the Malaysia Airlines flight that went missing on March 8 during a flight from Kuala Lumpur to Beijing.
Around 30 ships and 21 aircraft from Indonesia, Australia, Malaysia, Singapore and South Korea will search up to 10,000 square nautical miles on Tuesday, officials said.
Indonesian Air Force spokesman Hadi Tjahjanto said authorities would investigate an oil spill sighted on Monday, although a separate possible slick turned out to be a reef.
Searchers had investigated several areas where possible debris had been sighted in the water but had found nothing connected to the missing plane, Tjahjanto told Reuters news agency.
Authorities would also investigate reports by local fishermen of an explosion on Sunday morning off an island in the area, Tjahjanto added, although dynamite fishing is common in Indonesian waters.
The US military said the USS Sampson, a guided missile destroyer, would be on the scene later on Tuesday.
"We stand ready to assist in any way possible," a Pentagon spokesman said.
COULD PLANE HAVE STALLED?
What happened to flight QZ8501, which had sought permission from Indonesian air traffic control to ascend to avoid clouds, is still a mystery.
Online discussions among pilots highlighted unconfirmed secondary radar data from Malaysia that suggested the aircraft was climbing at a speed of 353 knots, about 100 knots too slow in poor weather, and that it might have stalled.
While searchers had picked up an emergency locator signal off the south of Borneo, no subsequent signal was found, officials said.
The plane, whose engines made by CFM International, lacked real-time engine diagnostics or monitoring, a GE spokesman said. Such systems are mainly used on long-haul flights and can provide information to airlines and investigators when things go wrong.
Officials said the sea in the general search area was only 50 to 100 metres (150 to 300 feet) deep, which would be a help in finding the plane.
"The Java Sea area where they are now searching isn't even an ocean, it's more of an inland sea," Erik van Sebille, a physical oceanographer at the University of New South Wales in Sydney said.
"It's so shallow that they may just be able to spot the plane," said van Sebille, noting that sunlight travels through water up to about 100 metres.
Oceanographer Pattiaratchi said debris would normally be expected to float on the surface for around 18 days before sinking.
NO FOUL PLAY SEEN
On board Flight QZ8501 were 155 Indonesians, three South Koreans, and one person each from Singapore, Malaysia and Britain. The co-pilot was French.
US security officials said passenger and crew lists were being closely examined but so far nothing significant had turned up and that the incident was still regarded as an unexplained accident.
The plane, which did not issue a distress signal, disappeared after its pilot failed to get permission to fly higher because of heavy air traffic, officials said.
Pilots and aviation experts said thunderstorms, and requests to gain altitude to avoid them, were not unusual in that area.