The crucial black box of crashed AirAsia plane QZ 8501 has not yet been found on January 8, the 12th day of the search campaign, the National Search and Rescue Agency of Indonesia (Basarnas) said.

Bambang Soelistyo, Basarnas Chief, said in an attempt to find the plane’s tail, which is considered as the most important part since the beginning of the salvage as black boxes are usually placed in a plane’s tail, the agency has worked with the National Transportation Safety Committee, naval ships, and divers from the Indonesian Marines elite diving unit.

However, bad weather and huge waves have held back multinational efforts to find the wreckage, he added.

He reported that international forces helping Indonesia in the search of QZ 8501 are going to return their homes soon.

The plane's black box will transmit acoustic "pings" for about 30 days, after which it will need to be manually located. With the plane having fallen off radars on December 28, there are less than 20 days left before QZ8501's black box stops transmitting signals.

A total of 41 bodies of victims on the ill-fated AirAsia flight, which crashed into the Java Sea, Indonesia have been found so far.

Among them, 39 have been brought to Surabaya, Indonesia, for identification test and to return to their families.

AirAsia Flight QZ8501 lost contact with an air traffic control station in the morning of December 28, only 42 minutes after taking off from Indonesia’s Surabaya airport for Singapore. It carried 162 passengers and crew members, including 155 Indonesians, three Koreans, one Singaporean, one Malaysian, one French, and one British.-VNA