PANGKALAN BUN, INDONESIA — Efforts to raise the tail of AirAsia flight QZ8501 failed for the second day running, but pings were detected in an area where search and recovery personnel are scouring the Java Sea, which the authorities believe to be from the all-important black boxes.

The suspected pings were detected about 500m to 1km from the jet’s tail, with 11 Indonesian ships, divers and underwater vehicles scouring an area 30km from the suspected site of the crash.

National Transportation Safety Committee (NTSC) investigator Santoso Sayogo said the flight data recorders appeared to be no longer in the tail and divers would need to confirm the exact position when the search resumes today.

The Singapore-bound flight vanished from radar screens on Dec 28 while flying over the Java Sea. It had taken off from Surabaya with 162 people on board. A total of seven bodies were retrieved yesterday, three of them by Japanese ships aiding the search. All seven were flown to Surabaya yesterday evening, bringing the total number of bodies sent to the East Java city to 48.

The pings were detected by Indonesia’s National Search and Rescue Agency (BASARNAS). Speaking to the press, BASARNAS director of operations S B Supriyadi said divers scouring the area around the tail had failed to locate the black box.

Though the wreckage is located only 30m underwater, strong currents and visibility of only 1m has made it difficult for divers and underwater vehicles to operate.

Nonetheless, Mr Supriyadi was confident that the pings were indeed from the jet’s flight recorders, citing reports from search and rescue ships showing the pings were detected within just 1km of the tail.

Fourteen divers on KN Jadayat — one of 11 ships near the jet’s tail — will be on standby for search operations today, he said.

Meanwhile, efforts by the KRI Banda Aceh to bring the jet tail to the surface have failed for the second day running, despite the lifting balloons that Indonesian search teams had loaded on helicopters to aid in raising the tail. BASARNAS chief Fransiskus Bambang Soelistyo said divers had intended to tie straps to the tail, which would be lifted using the balloons combined with cranes to avoid any damage.

However, the tail, which is partially buried on the seabed, turned out to be heavier than expected. “The plane is heavier now,” said Mr Supriyadi. “Mud and sand have gone inside the tail.”

The Indonesian authorities believe the plane tail weighs more than their initial estimate of 10 tonnes. Efforts to connect a rope to the tail also failed yesterday due to bad weather, officials said.

Including the 11 ships near the tail, 63 ships, nine planes and 13 helicopters from various countries resumed the search off Kalimantan.