All 132 people on board were killed.
One of the two black box recorders found in the wreckage of a China Eastern Airlines flight, investigators are hoping to shed light on why the passenger plane fell from the sky and crashed into a mountain in southern China, authorities said Wednesday.
None of the 123 passengers and nine crew members on Flight 5735 survived when it crashed in the Guangxi area.
An official with China’s Civil Aviation Administration confirmed on Wednesday that a recording device had been located. The official said the protective outer part of the box was severely damaged.
During a news conference Wednesday, Chinese authorities said they believed the device recovered was a cockpit voice recorder. It was found at the main impact point of the accident and was sent to Beijing for repair and analysis, officials said.
Authorities have for the first time publicly acknowledged that human remains were found at the crash site.
Investigators are still searching for a second recorder that stores flight data, including aircraft speed, altitude and wing flap position.
Preliminary data show that the Boeing 737-800 sank from 29,000 feet to 8,000 feet, leveled and then flew into a freefall, exploding in a fireball that people in the vicinity saw and imagined. A video shows the plane sinking to the ground with its nose.
“What the cockpit voice recorder is going to tell us is what the pilots were saying to each other. What were they doing? That would mean the difference between being able to tell, well, obviously, they had a big emergency. They were all fighting downhill, or maybe in the cockpit. There was only one. We don’t know, “said John Nance, a former commercial pilot who contributed to ABC News.
The plane crashed after taking off from Kunming, the capital of China’s Yunnan province. Chinese officials said the flight was en route to Guangzhou, a port city in northwestern Hong Kong.
Air traffic controllers repeatedly tried to radio the flight crew when they noticed a rapid landing, but were unable to restore contact with the crew before the crash, Chinese officials said.
U.S. intelligence has no idea what caused the plane to crash. A source told ABC News that they are not canceling anything, including possible intentional downs.
“The faster the airliner hits the ground, at almost the speed of sound, the more likely it is that it will change the aircraft and everything in it,” Nance said. “However, the cockpit voice recorder and the flight data recorder are on the tail of the aircraft, which slows down enough to reach the ground.
As a precaution, China Eastern Airlines grounded its fleet of Boeing 737-800s on Wednesday.
Members of the US National Safety Transportation Board, the Federal Aviation Administration, Boeing and engine-maker CFM International are all joining the investigation.
Amanda Mail of ABC News contributed to this report.