Jakarta, Indonesia (CNN) Searchers said Monday they had found both flight recorders from AirAsia Flight QZ8501 in the Java Sea, a major breakthrough in the effort to figure out why the plane crashed last month.

Divers found the flight data recorder under the wreckage of one of the plane's wings, said Bambang Soelistyo, the head of Indonesia's search and rescue agency.

The search teams have also found but not yet recovered the other key source of information about the plane: the cockpit voice recorder, said Mardjono Siswosuwarno, the chief investigator into the crash.

The voice recorder is underneath debris, he said, expressing hope that it could be retrieved easily.

The two devices, known popularly as black boxes, are seen as crucial to unraveling the mystery of what brought down Flight QZ8501 as it flew toward Singapore from the Indonesian city of Surabaya with 162 people on board.

Finding the data recorder is "a huge step in the right direction for investigators," said CNN aviation correspondent Rene Marsh. "It gives them so much information that they didn't have before."

Photos: The search for AirAsia Flight QZ8501 Photos: The search for AirAsia Flight QZ8501 Crews remove the fuselage of AirAsia Flight QZ8501 from a vessel at the Tanjung Priok Port in Jakarta, Indonesia, on Monday, March 2. AirAsia Flight QZ8501 was en route from Surabaya, Indonesia, to Singapore when it lost contact with air traffic control on December 28. There were 162 people on board. Hide Caption 1 of 47 Photos: The search for AirAsia Flight QZ8501 The fuselage is lifted from the Java Sea during the recovery mission on March 2. Hide Caption 2 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian search and rescue personnel unload recovered bodies at the Kumai seaport on Sunday, February 8. Hide Caption 3 of 47 Photos: The search for AirAsia Flight QZ8501 Workers load the tail of the plane onto a truck February 7 at the Kumai seaport. Hide Caption 4 of 47 Photos: The search for AirAsia Flight QZ8501 Crew members inspect body bags on the deck of a ship in the Java Sea on Friday, January 23. Hide Caption 5 of 47 Photos: The search for AirAsia Flight QZ8501 A police officer stands guard near pieces of the plane's wreckage at a warehouse in Pangkalan Bun, Indonesia, on Monday, January 19. Hide Caption 6 of 47 Photos: The search for AirAsia Flight QZ8501 This photo, taken by a remotely operated underwater vehicle and released Wednesday, January 14, by Singapore's Defense Ministry, shows part of the plane's fuselage lying on the floor of the Java Sea. Hide Caption 7 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian officials remove the cockpit voice recorder from AirAsia Flight QZ8501 on Tuesday, January 13. Indonesian divers retrieved it from beneath the wreckage of the plane. Hide Caption 8 of 47 Photos: The search for AirAsia Flight QZ8501 A flight data recorder was retrieved from the Java Sea on Monday, January 12. Hide Caption 9 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian worker cuts part of the plane's tail January 12 after debris from the crash was retrieved from the Java Sea. Hide Caption 10 of 47 Photos: The search for AirAsia Flight QZ8501 A portion of the plane's tail section is seen on the deck of a rescue ship after it was recovered from the Java Sea on Saturday, January 10. Hide Caption 11 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian rescue helicopter flies during search operations in the Java Sea on Friday, January 9. Hide Caption 12 of 47 Photos: The search for AirAsia Flight QZ8501 Search personnel unload the body of a victim upon arriving at the airport in Pangkalan Bun on January 9. Hide Caption 13 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Indonesian Search and Rescue Agency carry pieces of the jet in Pangkalan Bun on January 9. Hide Caption 14 of 47 Photos: The search for AirAsia Flight QZ8501 There was a major breakthrough in the search for the wreckage on Wednesday, January 7. Indonesian search and rescue officials released an image of the plane's tail section as seen on the floor of the Java Sea. Hide Caption 15 of 47 Photos: The search for AirAsia Flight QZ8501 Writing could be made out, showing the AirAsia insignia and other identifying features. The find is important because the plane's flight recorders were located in the tail section. Hide Caption 16 of 47 Photos: The search for AirAsia Flight QZ8501 Divers were sent to take images of the section after metal detectors identified large objects in the water where officials were searching for the lost plane. Hide Caption 17 of 47 Photos: The search for AirAsia Flight QZ8501 Search and rescue personnel carry seats from the flight on Monday, January 5. Hide Caption 18 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian navy member holds a piece of window panel that was recovered during search operations. Hide Caption 19 of 47 Photos: The search for AirAsia Flight QZ8501 Crew members in an Indonesian air force helicopter look out of the windows over the Java Sea during a search operation on Sunday, January 4. Hide Caption 20 of 47 Photos: The search for AirAsia Flight QZ8501 Members of an Indonesian search and rescue team carry items recovered from the search area in Pangkalan Bun on January 4. Hide Caption 21 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Mawar Sharon Church attend a prayer service for the relatives of lost loved ones January 4 in Surabaya, Indonesia. Hide Caption 22 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian navy officers coordinate the recovery of bodies taken to the vessel KRI Banda Aceh during recovery operations on Saturday, January 3. Hide Caption 23 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Indonesian navy return to the vessel with remains recovered from the crash area. Hide Caption 24 of 47 Photos: The search for AirAsia Flight QZ8501 Recovered victims are placed on the deck of the Indonesian ship on January 3. Hide Caption 25 of 47 Photos: The search for AirAsia Flight QZ8501 Members of an Indonesian search team carry a coffin at Iskandar Air Base on Friday, January 2. Hide Caption 26 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives and friends grieve as they attend a ceremony January 2 in Surabaya. Hide Caption 27 of 47 Photos: The search for AirAsia Flight QZ8501 A member of the Indonesian Red Cross prepares coffins at a hospital in Pangkalan Bun on January 2. Hide Caption 28 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the National Search and Rescue Agency and Indonesian soldiers carry coffins containing bodies of victims in Pangkalan Bun on January 2. Hide Caption 29 of 47 Photos: The search for AirAsia Flight QZ8501 This photograph released by the Singapore Defense Ministry shows the front and back of a piece of debris that resembles an aircraft window panel. Hide Caption 30 of 47 Photos: The search for AirAsia Flight QZ8501 Members of a search and rescue team carry the body of a victim in Pangkalan Bun on Thursday, January 1. Hide Caption 31 of 47 Photos: The search for AirAsia Flight QZ8501 Marine divers prepare their gear on the deck of a ship before searching for passengers and debris January 1 at Kumai port in Pangkalan Bun. Hide Caption 32 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian soldiers carry a victim's coffin upon arrival at an air force base in Surabaya on Wednesday, December 31. Hide Caption 33 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian soldiers carry coffins of crash victims on December 31. Hide Caption 34 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives of passengers pray together inside a holding room at Juanda International Airport in Surabaya on December 31. Hide Caption 35 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian air force personnel show debris, including a suitcase, that was found floating near the site where the AirAsia flight disappeared. Hide Caption 36 of 47 Photos: The search for AirAsia Flight QZ8501 Debris floats in the Java Sea on December 30. Hide Caption 37 of 47 Photos: The search for AirAsia Flight QZ8501 A member of the Indonesian navy monitors a radar screen during a search operation over the waters near Bangka Island, Indonesia, on December 30. Hide Caption 38 of 47 Photos: The search for AirAsia Flight QZ8501 Family members of missing passengers react at an airport in Surabaya after watching news reports on December 30. Hide Caption 39 of 47 Photos: The search for AirAsia Flight QZ8501 Debris floats in the Java Sea on December 30. Hide Caption 40 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives of missing passengers comfort each other December 30 at Juanda International Airport in Surabaya. Hide Caption 41 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives gather at Juanda International Airport as they wait for news on December 30. Hide Caption 42 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian military airman looks out the window of an airplane during a search over the waters of Karimata Strait on Monday, December 29. Hide Caption 43 of 47 Photos: The search for AirAsia Flight QZ8501 Members of Indonesia's Marine Police pray before a search operation on December 29. Hide Caption 44 of 47 Photos: The search for AirAsia Flight QZ8501 Military personnel perform a search operation on Sunday, December 28. Hide Caption 45 of 47 Photos: The search for AirAsia Flight QZ8501 Sunu Widyatmoko, CEO of Indonesia AirAsia, gives a press conference in Surabaya announcing that the flight lost contact with air traffic control. Hide Caption 46 of 47 Photos: The search for AirAsia Flight QZ8501 An official from Indonesia's national search and rescue agency points to the position where AirAsia Flight QZ8501 went missing. Hide Caption 47 of 47

Coupled with the debris that's already been collected, the data recorder will enable investigators to "begin to paint the picture of exactly what happened when things went terribly wrong for this aircraft," Marsh said.

Recorder's location 'is a clue'

The data recorder is expected to provide a vast range of information about what the plane was doing, including its air speed, engine performance and the cabin pressure.

The discovery of the device under the wreckage of a wing is significant, according to Mary Schiavo, a former inspector general of the U.S. Department of Transportation.

"That itself is a clue, because I think that pretty much indicates that the plane broke apart when it hit the water," she said, adding that if the aircraft had broken up at a high altitude, investigators wouldn't "have found the wreckage that close together."

One Indonesian search official, who goes by the single name of Supriyadi, said the debris pattern suggests the aircraft "exploded" on impact.

But the country's transportation investigators said it was premature to speculate about what had happened, and one expert questioned the search official's choice of words.

"The word 'exploded' I think maybe loses a little bit in translation," said David Soucie, a former Federal Aviation Administration safety inspector. "I think really what he's meaning is a rupture from the impact itself."

"As with any hollow object hitting something very hard, the pressure differential between the outside and the inside is very significant and it'll actually tear apart the aircraft on the top," Soucie told CNN. "That may be what he's referring to."

Reams of data

The cockpit voice recorder is expected to give insight into how the pilots responded to the crisis that brought down the plane. It captures all sounds on the flight deck, notably conversations between the crew members.

The flight data recorder is expected to be taken to a lab in Jakarta, the Indonesian capital, for analysis.

Once the information is downloaded, investigators should have "a pretty good idea within a couple of days" of what happened aboard the plane, Schiavo said.

The devices usually contain hundreds of parameters and thousands of data points, she said, that look a bit like an EKG when they're printed out.

But Schiavo added that she didn't think officials would release any information publicly for a couple of weeks.

French aviation experts are helping the Indonesian investigation, which also expected to involve Airbus, the manufacturer of the downed plane, an A320-200.

The tail section of the aircraft, which houses the black boxes, was lifted from the Java Sea on Saturday. But searchers didn't find the flight recorders inside it.

The flight data recorder was found about 2.5 kilometers (1.5 miles) from the location of the tail, according to Soelistyo, the head of the search agency.

Most bodies still missing

Searchers are still looking for the plane's fuselage, where many of the bodies of those on board the plane might be located.

A total of 48 bodies have so far been recovered from the sea, some of them still strapped into seats. Authorities have identified most of them.

Eben Tanapurtra, who lost seven family members in the disaster, told CNN that he was happy to hear the flight data recorder has been found but that his family and others hope authorities won't focus only on the black boxes.

"Please, please, continue the search for the missing bodies," he said. "We understand that the black box is crucial and so important for investigation. But please, do not consider the efforts to find the bodies as a less important thing."

Bad weather has hampered the search efforts for the aircraft, which are now in their 16th day. Flight QZ8501, operated by AirAsia's Indonesian affiliate, went down on December 28.

The pilot had requested permission to turn and climb to a higher altitude minutes before contact was lost, according to Indonesian officials.