The cockpit voice recorder, that possesses the last two hours of conversation between the pilots and with air traffic controllers, was found close to where the flight data recorder was recovered from the bottom of the choppy waters on Monday.
It was freed from beneath the heavy ruins of a wing early in the morning from a depth of about 30 metres, said Tonny Budiono, sea navigation director at Indonesia's transportation ministry.
This comes as a major potential breakthrough to solve the mystery of the Airbus A320-200's fatal crash on December 28 that killed all 162 people on board, after days of multi-national efforts to scour the seabed were hampered by bad weather.
Divers took advantage of calmer mornings yesterday and today to retrieve the black box — designed to survive extreme heat and pressure — usually inside the tail section but found missing from the wreckage when it was pulled out.
Earlier, an official said the cockpit voice recorder — part of two recorders that make up the black box — was on an Indonesian navy ship and and will be flown to Jakarta to be downloaded and analyzed with the flight data recorder.
"This is good news for investigators to reveal the cause of the plane crash," said Tonny Budiono, sea navigation director at the transportation ministry.
"Today we have completed searching for the main things that we have been looking for," Rear Admiral Widodo, the commander of the navy's western fleet, told reporters.
"But the team will still try to find the body of the plane in case there are still bodies inside," he said.
Only 48 bodies, including at least two strapped to their seats, have been found in the choppy waters so far despite over two weeks of search operations.
The black box recorders, which are actually orange, are expected to shed new light on the mysterious crash that claimed all 162 lives on board the ill-fated AirAsia Flight QZ8501, en route from Indonesia's Surabaya city to Singapore.
Investigators may need up to a month to get a complete reading of the data to determine what caused the AirAsia group's first fatal accident half way into a two-hour flight.
Since the device records in a two-hour loop, all discussions between the captain and co-pilot should be available.
In another crucial development on Tuesday, divers may have found one of the plane's engines that has a control unit to record data about performance, said Nurcahyo Utomo from the transport committee.
"If something is wrong with the engine, or weird, it will be recorded," he said.
The suspected location of the Airbus A320-200 engine could not be immediately confirmed, Channel NewsAsia reported, citing an investigator.
Search teams have also possibly identified the locations of the plane's main fuselage and stabilizer, with divers reported to have marked out the spot the fuselage is believed to lie, 30 metres deep, the report said.
Search and rescue agency coordinator S B Supriyadi said the fuselage is believed to have been found northeast of where the tail section was previously spotted by a ship scanning for wreckage, CNN reported.
The discovery of the fuselage would be a significant development, as officials believe it contains the remaining bodies of victims.
Officials on Monday gave new dramatic details of the accident, with Supriyadi saying an initial analysis of the wreckage recovered so far indicated the plane exploded on impact with the water due to a rapid change in pressure.
Meanwhile, chief of Indonesia's search and rescue agency BASARNAS Fransiskus Bambang Soelistyo on Tuesday said the legal timeframe for retrieving bodies is seven days.
Though focus of the operation shifted on the 11th day when the black box was found, the search for bodies continued, he told a parliamentary hearing in Jakarta.
"Our main task is to find the victims. "Even if both (black boxes) are found, it doesn't mean that our operation is over," he told reporters before heading to Surabaya to meet the victims' families.
He said BASARNAS was focused on finding the bodies while the armed forces were focused on finding the fuselage, that officials initially believed to contain the remaining bodies. However, all 48 bodies recovered so far were found spread out in the sea.
Soelistyo promised families that he will try his best to find all the passengers that were on board the AirAsia flight.
Meanwhile, the airline's flamboyant boss Tony Fernandes issued a message to customers, saying "the past few weeks have been the most difficult weeks of my life since starting AirAsia 13 years ago".
"We will continue to provide updates as the investigation goes on," the AirAsia head said as he vowed to overcome the crisis: "Even in our toughest times, we will continue to be the world's best and be better for you."