Indonesian officials believe they may have located the tail  and parts of the fuselage of the Airbus A320-200 at the bottom of the Java Sea, but strong currents, high winds and big waves have hindered attempts to investigate the debris.

Flight QZ8501 plunged into the water off Borneo island on Dec. 28, about 40 minutes into a two-hour flight from Indonesia's second-biggest city of Surabaya to Singapore. There were no survivors among the 162 people on board.

READ: AirAsia crash: Another body, fifth object found amid bad weather

Jakarta has launched a crackdown on its fast-growing aviation sector since the crash, reassigning some officials and tightening rules on pre-flight procedures in a country with a patchy reputation for air safety.

"Today's weather is friendly, the team can work," the head of Indonesia's search and rescue agency, Fransiskus Bambang Soelistyo, told a news conference in Jakarta.

ALSO READ: AirAsia jet engine dies before takeoff, passengers disembark

Soelistyo said the multinational air and sea operation had two objectives: to recover bodies and wreckage floating in an ever-widening search area in the northern Java Sea, and to find wreckage and the plane's black box on the ocean floor.

The latter effort is focused on an area about 90 nautical miles off Borneo, where ships using sonar have located five large objects believed to be parts of the plane - the largest about 18 metres (59 feet) long - in shallow water.

The captain of an Indonesian navy patrol vessel said on Monday his ship had found what was believed to be the tail - a key find since that section of the aircraft houses the cockpit voice and flight data recorders - but Soelistyo said that could not be confirmed.

READ: Weather believed to be factor in AirAsia crash: Indonesia

Only 37 bodies of the mostly Indonesian passengers and crew have been recovered. Many more could still be trapped in the fuselage of the aircraft.

"Why are we trying to search the big parts of wreckage? Because there might be the possibility that there are still victims in the body of the plane," said Soelistyo.

READ HERE: AirAsia crash: Some victims found belted in seats

Some divers were in action, and five ships were scouring the sea floor with acoustic "pinger" detectors designed to pick up signals emitted by the black box, he said.

China sends naval ship to locate black box of AirAsia flight

China has dispatched a naval rescue ship to join the search operations to locate the black box of the ill-fated AirAsia jet which crashed into the sea en route to Singapore from Surabaya, killing all 162 people onboard.

READ: Indonesia naval captain says may have located missing plane's tail section

Equipped with underwater search and detect devices and 48 divers, the Peoples' Liberation Army naval vessel left the Sanya port last night and would reach the area of the crash on January 9.

The ship, which earlier took part in the search operation of the missing Malaysian airliner MH370, will help in the search for the debris of the Airbus 320-200 Flight QZ8501 and bodies of the victims.

The missing plane is believed to have crashed into the Java Sea on December 28.

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