SURABAYA, Indonesia — More planes and ships joined an expanding search Tuesday for AirAsia Flight 8501, which disappeared over the Java Sea on Sunday with 162 people aboard.

At least 30 ships, 15 planes and seven helicopters were looking for the jet, said Indonesia’s Search and Rescue Agency chief Henry Bambang Soelistyo. Most of the craft were Indonesian, while Singapore, Malaysia and Australia contributed to the effort. Aircraft crews from Thailand also planned to join the search Tuesday.

He said the search area would be expanded to land areas, with four military helicopters dispatched just after sunrise near Pangkalan Bun on the western part of Borneo island and to smaller islands of Bangka and Belitung.

“Until now, we have not yet found any signal or indication of the plane’s whereabouts,” Soelistyo told The Associated Press.

The U.S. Navy said in a statement that the USS Sampson, a destroyer that was already on an independent deployment in the Western Pacific, will arrive in the area later Tuesday. China announced that a navy frigate and aircraft will join the search.

The longer the search goes without turning up wreckage or a hint of what happened to the plane, the more the incident will evoke memories of the still-unsolved disappearance of Malaysia Airlines Flight 370 in March.

The AirAsia pilots had been worried about the weather and had sought permission to climb above threatening clouds. Air traffic control couldn’t say yes immediately – six other airliners were crowding the airspace, forcing Flight 8501 to remain at a lower altitude.

Minutes later, the jet was gone from the radar without issuing a distress signal. The Airbus A320-200 is believed to have crashed into Indonesia’s Java Sea, but broad aerial surveys so far have turned up no firm evidence.

On Monday, searchers spotted two oily patches and floating objects in separate locations, but it was not known if any of it was related to the plane that vanished, halfway into what should have been a two-hour hop from Surabaya, Indonesia, to Singapore. The area is a busy shipping lane. Officials saw little reason to believe the flight had not crashed.

Based on its last known coordinates, the aircraft probably crashed into the water and “is at the bottom of the sea,” Bambang Soelistyo said Monday. Still, searchers planned to expand their efforts onto land on Tuesday.

The last communication from the cockpit to air traffic control was a request by one of the pilots to climb from 32,000 feet to 38,000 feet because of bad weather.

A storm alone isn’t going to bring down a modern plane designed to withstand severe weather. But weather paired with a pilot error or a mechanical failure could be disastrous.

Pilots rely on sophisticated weather-radar systems that include a dashboard display of storms and clouds, as well as reports from other crews, to steer around dangerous weather.

“A lot more information is available to pilots in the cockpit about weather than it ever was,” said Deborah Hersman, former chairman of the U.S. National Transportation Safety Board. But the technology has limits and information about storms “can be a little bit stale.”

The captain, Iryanto, who like many Indonesians uses a single name, had more than 20,000 flying hours, AirAsia said.

Jakarta’s air force base commander, Rear Marshal Dwi Putranto, said an Australian Orion aircraft had detected “suspicious” objects near an island about 100 miles off central Kalimantan. That’s about 700 miles from where the plane lost contact, but within Monday’s greatly expanded search area.

“However, we cannot be sure whether it is part of the missing AirAsia plane,” Putranto said.

Air Force spokesman Rear Marshal Hadi Tjahnanto told MetroTV that an Indonesian helicopter spotted two oil patches in the Java Sea east of Belitung island, much closer to where the plane lost contact. He said oil samples would be collected and analyzed.

An Associated Press photographer flew in a C-130 transport carrier with Indonesia’s Air Force for 10 hours Monday over a large section of the search area between Kalimantan and Belitung. The flight was rainy at times. It flew low, easily spotting waves, ships and fishermen, but there was no sign of the plane.

The suspected crash caps a tragic year for air travel in Southeast Asia, and Malaysia in particular. Malaysia-based AirAsia’s loss comes on top of the mystery surrounding Malaysia Airlines Flight 370 in March with 239 people aboard, and the downing of Malaysia Airlines Flight 17 in July over Ukraine, which killed all 298 aboard.

Nearly all the passengers and crew on the AirAsia flight are Indonesians, who are frequent visitors to Singapore.

Ruth Natalia Puspitasari, who would have turned 26 on Monday, was among them. Her father, Suyanto, sat with his wife, who was puffy-eyed and coughing, near the family crisis center at Surabaya’s airport.

“I don’t want to experience the same thing with what was happened with Malaysia Airlines,” he said as his wife wept. “It could be a long suffering.”

Few believe this search will be as perplexing as the ongoing one for Flight 370, the fate of which remains a total mystery. Authorities suspect the plane was deliberately diverted by someone on board and ultimately lost in a remote area of the Indian Ocean. Flight 8501 vanished over a heavily traveled sea that is relatively shallow, with no sign of foul play.