Wuzhou - Search and rescue work of the China Eastern Airlines crash entered its fourth day, with efforts focusing on retrieving the second black box while the first was being decoded and analysed in Beijing.

Emergency workers on the ground have been scouring the forest-clad mountains of China's southern Guangxi region for victims of Flight MU5735 that crashed on Monday. No survivors have been found so far in a tragedy that has shocked the nation.

The jet en route from the southwestern city of Kunming to Guangzhou on the coast, plummeted from cruising altitude at around the time it should have started its descent to its destination.

A black box is a flight data recorder that records all flight information with a specific algorithm. This makes the recorded flight data accessible to authorities when needed. The black box is mostly bright orange, not black. Black boxes are resistant to the most extreme situations and are one of the most special tools of the aviation research industry with their voice recording features.

Rescuers recovered one of the two black boxes on Wednesday. The device, the plane's cockpit voice recorder, has been sent to Beijing. It could take 10 to 15 days to arrive at a preliminary analysis, and longer before a final conclusion can be presented in a report, according to Chinese state media.

More than 200 distraught family members of the 132 people on board the crashed flight have visited the crash site.

It was too early to determine the cause of the crash, which experts say are usually the result of a combination of factors.
-Reuters