Divers fought strong currents and waves as they worked to hoist the tail of the crashed AirAsia plane out of the Java Sea on Saturday, two weeks ago after it went down, killing all 162 people on board.

Inflatable bags were being attached to the rear of the aircraft, and a crane will be used to lift it from a depth of about 30 meters.

``Additional lifting bags are needed because the tail part is getting heavier due to strong currents and piles of sand and mud,'' said Suryadi B. Supriyadi, the National Search and Rescue Agency's operational director.

Intermittent underwater ping-like sounds were picked up Friday about a kilometer (half mile) from where the tail was located, but it was unclear if they were coming from the cockpit voice and flight data recorders located in the back of the Airbus A320, he said. It was possible the signals were coming from another source.

He said no metal was detected at the ping location, but that the black boxes could have come loose from the plane.

Nurcahyo Utomo, a National Commission for Transportation Safety investigator, said the sounds could not be confirmed.

Meanwhile, Transportation Minister Ignasius Jonan cracked down on five airlines Friday, temporarily suspending 61 flights, because they were flying routes on days without permits. Earlier, all AirAsia flights from Surabaya to Singapore, the path Flight 8501 was on when it went down Dec. 28, were suspended after it was discovered that the low-cost carrier was not authorized to fly on Sundays.

Transportation Minister Ignasius Jonan also sanctioned nine more officials for allowing the plane to fly without permits, bringing the total to 16. 

The discovery of the plane's tail earlier this week was a major breakthrough in the slow-moving search that has been hampered by seasonal rains, choppy seas and blinding silt from river runoff. Officials were hopeful the black boxes were still inside. They are key to helping investigators understand what caused the crash.

The last contact the pilots had with air traffic control, about halfway into their two-hour journey, indicated they were entering stormy weather. They asked to climb from 9,753 meters to 11,582 meters to avoid threatening clouds, but were denied permission because of heavy air traffic above them. Four minutes later, the plane dropped off the radar.

Four additional bodies were recovered Friday _ two of them still strapped in their seats on the ocean floor – bringing the total to 48. Officials hope many of the remaining corpses will be found inside the fuselage, which has not yet been located by divers. Several large objects have been spotted in the area by sonar. (AP)