PANGKALAN BUN, Indonesia (AFP) - Indonesian military divers on Saturday chased faint signals believed to be from the black box data recorders of Indonesia AirAsia flight QZ8501 that crashed in stormy weather, killing all 162 people on board.
"Last night, our divers had opened the door of the tail cabin, searched around but found nothing," S.B Supriyadi, a director with the National Search and Rescue Agency Basarnas, told AFP.
"But the boat above detected faint ping sounds believed to be from the black boxes about one mile (1.6 kilometres) southeast of the tail... and covered in mud."
Supriyadi said the divers from an elite Marines unit returned on Saturday morning to the area believed to be where the pings were emanating from more than 30 metres underwater.
"They are searching within a radius of 500 metres from where the pings are emitted. The challenge is that these sounds are very faint. If a ship passes by, the sounds will be drowned out. So we really need calm waters," he said.
"So far, our divers still have not been able to determine the coordinates of the black box."
Flight QZ8501 went missing on Dec 28 as it flew from the Indonesian city of Surabaya to Singapore, and the tail of the plane was found 10 days later on the floor of the Java Sea.
Search efforts have since focused heavily on trying to find the black boxes, which are crucial to explaining why the plane crashed as they should contain the pilots' final words as well as various flight data.
Pings from the boxes, which were stored securely in the tail, were detected on Friday, raising hopes of quickly retrieving them.
But the search took another frustrating twist when authorities realised the pings were likely coming away from the tail, and the boxes appeared to be buried deep into the sea floor.
Meanwhile, a parallel operation was taking place nearby from the Indonesian Navy's KRI Banda Aceh warship to lift the tail of the plane out of the water using giant balloons.
The balloons, some with a capacity to lift 35 tonnes, were to be attached to the tail, according to officials involved in the operation.
American, Chinese and other foreign naval ships are also involved in the hunt for other parts of the plane's wreckage, as well as for the bodies of the passengers and crew.
Just 48 bodies have been found so far, according to Indonesian authorities.
All but seven of those on board were Indonesian.