By Cindy Silviana and Kanupriya Kapoor
JAKARTA/PANGKALAN BUN, Jan 8 (Reuters) - Indonesian search and rescue teams plan to start lifting the crashed AirAsia jet's tail off the sea bed on Friday, officials said, raising hopes that "black box" recorders can be retrieved to reveal the cause of the disaster.
Scores of divers plunged into the Java Sea on Thursday to search the wreckage of Flight QZ8501, which vanished from radar screens on Dec. 28 less than half-way into a two-hour flight from Indonesia's second-biggest city of Surabaya to Singapore.
There were no survivors among the 162 people on board.
The cause of the crash remains a mystery, with hopes centring on the so-called black boxes - the flight data recorder and the cockpit voice recorder - providing vital clues.
The plane was an Airbus A320-200, which carries the recorders near the tail section. Officials have warned, however, that the recorders could have become separated from the tail during the disaster.
The tail of the plane was found on Wednesday, upturned on the sea bed about 30 km (20 miles) from the plane's last known location at a depth of around 28-32 metres.
"The weather prevented the operation to lift the tail today," search and rescue agency coordinator Supriyadi told reporters in Pangkalan Bun, the southern Borneo town closest to the crash site.
Choppy seas, strong currents and poor visibility have dogged the search throughout.
"The operation using (a) balloon to lift the tail will start tomorrow," Supriyadi added.
The head of Indonesia's search and rescue agency, Fransiskus Bambang Soelistyo, said separately in Jakarta that a crane might also be employed to lift the tail and that finding the missing bodies was still the main focus of the operation.
Relatives of the victims have urged authorities to make finding the remains of their loved ones the priority.
WEATHER MAY WORSEN
A total of 84 divers were in ships in the vicinity of the wreckage on Thursday and teams began searching the jet's tail at 0645 local time (2345 GMT Wednesday), with visibility poor and strong currents still impeding efforts, officials said.
Ships with acoustic "pinger locators" designed to pick up signals from the black boxes were at the location but were no longer being used, in a possible sign of confidence among Indonesian officials that the recorders will be found soon.
According to Nurcahyo Utomo, an investigator at the National Transportation Safety Committee (NTSC), the time taken to analyse what happened to the flight depended partly on the condition of the recorders.
The NTSC is leading the probe, with France's BEA crash investigation agency officially participating.
Forty-three bodies and debris from the plane have been plucked from the surface of the waters off Borneo, but strong winds and high waves have been hampering divers' efforts to reach larger pieces of suspected wreckage detected by sonar on the sea floor.
Weather agency officials warned on Thursday that although conditions at search areas had improved over the last two days, they were likely to worsen from Friday onwards.
Indonesia AirAsia, 49 percent owned by the Malaysia-based AirAsia budget group, has come under pressure from the authorities in Jakarta since the crash.
The transport ministry has suspended the carrier's Surabaya-Singapore licence, saying it only had permission to fly the route on Mondays, Tuesdays, Thursdays and Saturdays.
Flight QZ8501 took off on a Sunday, though the ministry said this had no bearing on the accident.
While the cause of the crash is not known, the national weather bureau has said seasonal tropical storms common in the area were likely to be a factor.
AirAsia has said it is cooperating fully with the ministry's investigations. That investigation would be completed by Friday evening, the transport ministry said.
Indonesia has already cracked down on the sale of cheap tickets for domestic flights to ensure that airlines do not cut corners on safety, the transport ministry said on Thursday.
The decision to tighten the rules on budget fares came into effect on Dec. 30. The ministry's intention is to help to increase airlines' profit margins, allowing them to spend more on safety.
(Additional reporting by Michael Taylor, Eveline Danubrata, Gayatri Suroyo, Wilda Asmarini, Nilufar Rizki and Charlotte Greenfield in Jakarta; Editing by Raju Gopalakrishnan and Mike Collett-White)