JAKARTA, Jan. 6 (Xinhua) -- Three Chinese experts arrived in Jakarta on Tuesday to join the search operation for the black box of the AirAsia QZ8501 flight, after the ill-fated plane crashed en route from Indonesia's Surabaya to Singapore late last December.

The three experts from Civil Aviation Administration of China arrived in Soekarno Hatta Airport early Tuesday morning, marking the arrival of the first batch of Chinese aid in the search operation for AirAsia QZ 8501.

"We are here to help the search for the black box," Mao Yanfeng, director of disaster investigation agency under the Civil Aviation Administration of China, told Xinhua while waiting for the domestic flight heading towards the command post established at Pankalan Bun in Central Kalimantan.

"We can't elaborate on when the black box can be found or how long we will stay in Indonesia, before we get more information at Pangkalan Bun," said Mao, adding that they have brought along with them portable underwater detection equipment and communication device.

The AirAsia QZ 8501 is believed to have crashed into the Java Sea on Dec.28, with 162 people onboard. So far, 37 bodies have been discovered by a multinational search team. The black box which is crucial for the investigation of the accident is yet to be found, though theoretically it could emit signal.

The reason for not catching the signal could be complicated, said Mao, citing the internal failure of the black box and the signal blocked as possible factors.

He noted that, the side-scan sonar could also locate the black box, even after 30 days when the battery of black box died.

Five ships with specialized equipment is conducting the search for the black box at Northern Java Sea, according to Soelistyo, head of Indonesia's Search and Rescue Agency.

A Chinese rescue ship "Nanhaijiu 101" is expected to arrive directly in Pankalan Bun on Friday, after leaving Haikou, the capital city of China's Hainan Province, on Monday, said China's Ministry of Transport in a statement.