One black box from the China Eastern Airlines Boeing 737-800NG has been recovered from the crash site, according to state media.
The damages have made it unclear as to whether it is the flight data recorder or the cockpit recorder, but according to Mao Yanfeng, the director of the accident division of the Civil Aviation Authority of China (CAAC), there is a current investigation to retrieve the other one.
It comes only days after the aircraft crashed into the mountains in southern China on Monday, and all 132 people onboard are feared to be dead.
The aircraft, registration B-1791, was performing flight MU5735 from Kunming in Yunnan Province to Guangzhou in Guangdong Province with 123 passengers and nine crew onboard, when its altitude started to quickly drop.
Data from Flightradar24 suggests the six-year-old aircraft lost over 20,000 feet in altitude within under two minutes, falling from 29,000 feet to under 9,000. The aircraft began to climb again briefly once it hit 7,400 feet, however, within seconds again continued to descend.
The twin-engine jet impacted the ground about 119 nautical miles west of its destination, in the mountainous region of Wuzhou, about one hour and 37 minutes after take-off.
Black boxes, which are typically the size of a shoe box, sit inside the aircraft and record flight data and information. These have been essential in air crash investigations, often unveiling the last moments before the incident.
According to Chinese media the Global Times, as of 3:30pm on Thursday, a total of 21 possessions of the victims and 183 pieces of plane wreckage have been found.
The main impact of the crash has been determined, mostly in a core area of the mountain with a radius of about 30 metres.
Debris retrieved so far include blade and turbine fragments, engine pylon fragments, left and right horizontal tail fragments, aileron autopilot actuators and wing fragments, crew escape ropes, crew manual pieces and some certificates found in the cockpit, the Global Times said.
Investigators are still at the crash site, and some search and rescue personnel at a farmland in Tengzhou county, Wuzhou found a potential piece of debris, as long as 1.3 metres.
However, the piece of debris has not been confirmed yet.
As soon as the Chinese government heard of the crash, President Xi Jinping and the CAAC activated emergency protocols to carry out investigations.
The CAAC also issued an immediate Urgent Notice to promote industry-wide efforts of improving aviation safety.
Investigators are still unsure as to why the aircraft dropped nose down from the sky, and Mao told reporters that there had been “no dangerous weather” at the time.
A Boeing spokesperson said on Monday the company is aware of “initial media reports” of a crash and are “working to gather more information”. There have been no new updates from the planemaker.