The cockpit voice recorder from a crashed Indonesian jet has been retrieved in "good condition", officials said Wednesday, more than two months after the airliner plunged into the sea killing all 62 passengers and crew.
The CVR records flight crew conversations and could offer critical clues about why the Sriwijaya Air Boeing 737-500 dived around 3,000 metres (10,000 feet) into waters off Jakarta just minutes after takeoff on January 9.
The jet's flight data recorder, which holds information about the speed, altitude and direction of the plane, was earlier plucked from the wreckage-littered Java Sea.
Authorities said Wednesday that the voice recorder unit was in good condition, despite having been in the water for months.
"So we're confident that we will be able to download its data," said Soerjanto Tjahjono, head of Indonesia's National Transportation Safety Committee.
Investigators want to mine the recorder in the hopes of learning what the crew was saying when the flight from the capital to Pontianak in Borneo went down.
Cockpit voice and flight data recorders are known as black boxes and help explain nearly 90 percent of all crashes, according to aviation experts.
The voice device was found Tuesday evening on the last day of an operation that used dredging equipment to comb the muddy seabed, after the dive search failed to locate it, they said.
"It was like trying to find a needle in a haystack," Tjahjono told reporters earlier Wednesday.
"But without the CVR, it would be very difficult to find the cause of the Sriwijaya Air accident."
A preliminary report last month into the crash said crews on previous flights had described the jet's throttle system as "unserviceable" and that it had been repaired several times before its fatal final flight.
The report said a catastrophic throttle malfunction and possible human error were among the factors being considered.
But investigators had said it was too early to pinpoint a cause.
The 737 had sharply deviated from its intended course just before its plunge.
Despite appeals from air traffic controllers, the crew -- including an experienced captain -- did not respond to questions about the sudden change of direction.
The 26-year-old plane was flown by US-based Continental Airlines and United Airlines before it was purchased by Sriwijaya, which flies to destinations in Indonesia and across Southeast Asia.
Indonesia, a vast archipelago that relies heavily on air transport to connect its thousands of islands, has suffered a string of deadly plane crashes in recent years.
In October 2018, 189 people were killed when a Boeing 737 MAX jet with Lion Air plunged into the sea.
That accident -- and another in Ethiopia -- led to the worldwide grounding of the 737 MAX over a faulty anti-stall system.
The 737 that crashed in January was not a MAX variant.