PANGKALAN BUN: Indonesian divers Monday retrieved the flight data recorder of the AirAsia plane that went down in the Java Sea with 162 people on board, a potential breakthrough in efforts to discover what caused the crash.

But there was confusion about what happened in the final moments of Flight QZ8501, which crashed off the Indonesian coast on Dec. 28, with one official saying the plane probably exploded before hitting the water and another disputing that theory.

The second so-called black box, containing the cockpit voice recorder, is located about 20 meters away from where the flight data recorder was found, but divers have not yet been able to get to it.

The two instruments, which emit signals from their beacons, are vital to understanding what brought Flight 8501 down on Dec. 28. They should provide essential information about the plane and all of the conversations between the captain and co-pilot for the duration of the flight.

“There’s like 200-plus parameters they record,” said aviation safety expert John Goglia, a former US National Transportation Safety Board member. “It’s going to provide us an ocean of material.”

The slow-moving hunt, which has often gone days with little progress, was boosted over the weekend when the Airbus A320’s tail was lifted from the seabed. It was the first major wreckage excavated from the crash site, but the black boxes were not found inside as hoped.

Search efforts have been consistently hampered by big waves and powerful currents created by the region’s rainy season. Silt and sand, along with river runoff, have created blinding conditions for divers.

The flight data recorder was pulled from beneath a piece of the aircraft’s wing and brought to the sea’s surface, and the cockpit voice recorder was found hours later, said Suryadi Bambang Supriyadi, operation coordinator for Indonesia’s national search and rescue agency.

He said the voice recorder was about 20 meters from the data recorder but remained lodged beneath heavy wreckage, and divers were struggling to free it at a depth of 32 meters.

Officials said they believe the flight data recorder is in good condition and it was being flown to Jakarta on Monday. Indonesia’s National Transport Safety Committee said it would undergo a lengthy analysis in the capital, with the help of a team of experts including from France and manufacturer Airbus.

So far, only 48 bodies have been recovered. Decomposition is making identification more difficult for desperate families waiting to bury their loved ones. Nearly all of the passengers were Indonesian.

“I still believe many victims remain trapped there, and we must find them,” said Gen. Moeldoko, Indonesia’s military chief, who uses one name.