Until Flight QZ8501 went down everything had gone right during a spectacular 13-year run of success for AirAsia, which unlocked a booming market of budget travelers in the region.

But as long as no serious safety lapses emerge, analysts say the robust and media-savvy business built up by the Malaysia-based group should help overcome its first major reversal.

The tail of an AirAsia plane that crashed into the Java Sea was lifted to the surface using floating balloons on Saturday, but apparently without the crucial black box recorders, Indonesian authorities said.

The Airbus jet, carrying 162 people, went missing in stormy weather on December 28 as it flew from the Indonesian city of Surabaya to Singapore, and all aboard died.

Signals believed to be from the black box data recorders of crashed AirAsia Flight 8501 were detected Friday, Indonesian authorities said, offering the strongest lead to explain the disaster. 

"A ship detected the pings. The divers are trying to reach it," said S.B Supriyadi, a director with the National Search and Agency who is stationed at the search headquarters of Pangkalan Bun.

Elite Indonesian military divers battled strong currents on Thursday in an effort to reach the submerged tail of crashed AirAsia Flight 8501 in the hopes of finding its crucial black box data recorders.

The plane crashed on December 28 during stormy weather as it flew from the Indonesian city of Surabaya to Singapore, claiming the lives of all 162 people on board.

Vietnamese authorities on Wednesday denied widespread rumors that a popular senior communist party official had been poisoned with radioactive material by a political rival, state media said.

Nguyen Ba Thanh, 61, a former top official in Danang who helped turn the coastal city into a tourism and investment hub, is due to return to Vietnam this week after months of medical treatment in the United States.

Indonesia said Wednesday it had found the tail of an AirAsia plane that crashed into the sea with 162 people on board, raising hopes of finding its black boxes and explaining the disaster.

Search and rescue agency chief Bambang Soelistyo said he was sure of the discovery after divers took photographs of the tail, wedged into the seabed 30 metres (100 feet) underwater, on which the company's logo could be seen.

Indonesian recovery teams narrowed the search area for AirAsia Flight 8501 Friday, hopeful they were closing in on the plane's crash site, with a total of 30 bodies and more debris recovered from the sea.

French and Singaporean investigators joined the hunt for the Airbus A320-200, which disappeared from radar during a storm Sunday en route from Indonesia's second city of Surabaya to Singapore with 162 people on board. 

Passengers aboard AirAsia Flight QZ8501 were in a festive mood as they boarded the aircraft in Indonesia to fly to celebrate New Year with their loved ones in Singapore.

Their highly-regarded Indonesian pilot Iriyanto, 53, used to fly military fighters before taking early retirement and joining commercial airlines.

Dozens of planes and ships searching Indonesian waters for a missing AirAsia plane focused Monday on a patch of oil for possible clues, as a senior official warned the aircraft was likely at the bottom of the sea.

Australia, Malaysia and Singapore joined the Indonesia-led search as anguished relatives awaited news of their loved ones more than a day after Flight QZ8501 disappeared over the Java Sea with 162 people on board.

Indonesia suspended until first light the search for an AirAsia plane that went missing Sunday in the Java Sea with 162 people on board after the crew requested a change of flight plan due to stormy weather.