One black box found from crashed China Eastern flight

One of two "black box" recorders from a China Eastern passenger plane that crashed in southern China on Monday with 132 people on board has been found, a Chinese aviation official said on Wednesday.

Speaking at a news conference, Mao Yanfeng, the director of the accident investigation division of the Civil Aviation Authority of China, said that investigators had so far been unable to establish whether it was the flight data recorder or the cockpit voice recorder.

"The exterior appearance of the black box is severely damaged," Mao said, without giving details of the condition of the recording device inside the casing.

The retrieval of so-called black boxes following a crash is considered a key element in finding out the cause.

The flight data recorder captures information about the plane's airspeed, altitude, direction up or down, pilot actions, and performance of all key systems. The cockpit voice recorder captures sounds including conversations and background engine noise during the flight.

What do we know about the crash?

China Eastern Flight 5735, a Boeing 737-800, was carrying 123 passengers and nine crew from Kunming in Yunnan province to Guangzhou on China's southeastern coast.

It crashed on Monday afternoon outside the city of Wuzhou in the Guangxi region with all 132 people on board presumed killed, making it China's worst crash in more than a decade.

The plane went into an unexplained dive an hour after departure and stopped transmitting data 96 seconds into the fall, with aviation officials still mystified as to the cause of what seems to be an unmotivated descent.

Mao and other officials at Wednesday's news conference said the aircraft had a clean maintenance record, the weather had been good during the flight and the crew had been in regular communication with air traffic controllers before the dive commenced.

Shanghai-headquartered China Eastern is one of China's three largest carriers with more and has 109 Boeing 737-800s in its fleet.

The aircraft has been flying since 1998 and has a good safety record.