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 the Transportation Ministry.

This comes as a major potential breakthrough to solve the mystery of the Airbus A320-200's fatal crash on December 28 after days of multi-national efforts to scour the seabed were hampered by bad weather.

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 be flown to Jakarta to be downloaded and analysed with the flight data recorder.

"This is good news for investigators to reveal the cause of the plane crash," said Budiono.

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.

Officials yesterday gave new dramatic details of the accident, with search and rescue agency coordinator S B 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 today said the legal timeframe for retrieving bodies is seven days.

"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.

When asked about the chances of finding more bodies, he said it is harder to find bodies underwater than on the surface.

In another crucial development today, 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 stabiliser, with divers reported to have marked out the spot the fuselage is believed to lie, 30 metres deep, the report said.

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."

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