One of two black boxes from the China Eastern plane which crashed on Monday has been found in a severely damaged condition, investigators have said.

The recorder is so damaged that they are not able to tell whether it is the flight data recorder or the cockpit voice recorder.

Flight MU5735, a Boeing 737-800 carrying 132 passengers and crew, was travelling from Kunming to Guangzhou when it plunged from cruising altitude and crashed into mountains in Guangxi.

No survivors have been found so far.

Mao Yanfeng, the director of the accident investigation division of the Civil Aviation Authority of China, told a news conference that an all-out effort is being made to find the other black box.

Heavy rain has halted the search so far and rain water has filled the crater in the soft soil caused by the impact of the crash, state television reported.

Earlier, searchers had used hand tools, drones and sniffer dogs under rainy conditions to comb the heavily forested slopes for the flight data and cockpit voice recorders, as well as any human remains.

The local weather bureau in the Guangxi region said there was a risk of landslides, torrents and high winds as conditions deteriorate in the area.

Video clips posted by China’s state media showed small pieces of the aircraft scattered over the area.

Mud-stained wallets, bank and identity cards have also been recovered. Each piece of debris has a number next to it, the larger ones marked off by police tape.

Relatives of passengers began arriving Wednesday at the gate to Lu village just outside the crash zone, where they, along with reporters on the scene, were stopped by police and officials who used opened umbrellas to block the view beyond.

One woman, who said she had two children, made an emotional appeal to officials on site, asking to enter the area where the plane that killed her husband had crashed.

A 57-year old man, who gave only his surname Ding, said his sister-in-law was on the plane.

“My heart sank all of a sudden,” he said of learning about the plane’s accident.

What caused the crash?

Investigators say it is too early to speculate on the cause of the crash. The plane went into a dive mid-flight and stopped transmitting data 96 seconds into the fall.

FlightRadar24 data showed the aircraft plunged at a rate of 31,000 feet per minute – the height of a 50-storey building
every second.

An aviation safety official says an air-traffic controller tried to contact the pilots after seeing the sharp altitude drop, but got no reply.

Another official said the jet had met airworthiness standards before take-off and crew members had been in good health.

The plane had three pilots on board on its final flight, which is one more than normally required on a 737.

China’s aviation safety record

China had made great strides in improving air safety standards over the past two decades, and Monday’s disaster was
the first major crash in a dozen years.

Having rushed to Guangxi to oversee the emergency operations, Vice Premier Liu He held a meeting on Tuesday during
which officials were urged to go “all out in their search as long as there is a glimmer of hope”.

The disaster prompted the aviation regulator to launch a two-week inspection of the sector that will involve checks at
all regional air traffic control bureaus, airline companies and flight training institutes to ensure “absolute” safety.

Since the crash, China Eastern and two subsidiaries have grounded their fleet of more than 200 Boeing 737-800
jets.