Indonesian navy divers yesterday found the flight data recorder of the Sriwijaya Air Boeing 737-500 which plunged into the Java Sea shortly after take-off from Jakarta last Saturday, killing all 62 people aboard.
The device containing key data, such as airspeed and altitude, is one of two black boxes that will play a key role in investigations into the air crash. The flight data recorder covers up to 25 hours of flight, while the cockpit voice recorder monitors sound, including conversations between the pilot and co-pilot.
The head of the military, Air Chief Marshal Hadi Tjahjanto, told a press briefing yesterday - the fourth day of the search and rescue mission - that efforts were under way to recover the other black box soon.
The Indonesian National Transportation Safety Committee's (KNKT) chief Soerjanto Tjahjono yesterday said that the ill-fated plane did not explode or break apart before crashing into the sea just minutes into the flight.
Based on the field data, the wreckage was found in an area between 300m and 400m in length and 100m in width.
In a televised briefing about the committee's initial findings, he said: "The data about the spread of the wreckage reveals that the impact occurred at one point, or was very localised. This suggests that the explosion or breakage did not happen prior to impact."
The plane departed from Indonesia's main gateway Soekarno-Hatta International Airport on the outskirts of Jakarta, en route to Pontianak, the provincial capital of West Kalimantan, in the afternoon.
The final piece of data received from the aircraft was when it reached 250 feet from the water surface. Mr Soerjanto noted that the recorded data at 250 feet indicated that the aircraft system was functional and he suspected its engine was still operating before it hit the water.
More than a dozen helicopters, 54 navy ships and about 3,600 personnel were deployed in the rescue effort yesterday. The search area for the black boxes was narrowed to a region in the waters off the Thousands Islands north of Jakarta's coast.
The search and rescue effort has been hampered in the past few days by bad weather. The effort to retrieve the black boxes from the seabed was also hindered by mud and aircraft wreckage.
Air Chief Marshal Hadi said the flight recorder and its underwater locator beacon, as well as another one were found at 4.40pm Jakarta time (5.50pm Singapore time).
He said: "The search for the cockpit voice recorder will be done without the assistance from the beacon. But as the underwater locator beacon from the cockpit voice recorder was found around the area, we are highly confident it will soon be found too."
Mr Soerjanto of the KNKT said that it would take two to five days to download the data from the flight data recorder.