On the morning of the 27th, the search and rescue personnel at the scene of the "March 21" China Eastern Airlines flight accident found the flight data recorder (the second black box) of the crashed aircraft. So far, two black boxes of the crashed plane have been found. Around the second black box search process and subsequent decoding work, relevant experts answered. How was the second black box found? According to the on-site fire rescue personnel, at about 9:20 a.m. on the 27th, at the position 5 degrees east by south of the impact point in the core area and about 40 meters away from the impact point, when they dug to a depth of about 1.5 meters below the surface, they found a cylindrical metal tank wrapped in soil and exposed only a little orange after turning over a tree root. After purging and cleaning the dust on the surface of the metal tank, they exposed a clear English logo. The fire rescue personnel handed over the object to civil aviation experts for repeated identification and confirmed it as the second black box of the crashed aircraft. How is the location of the black box determined? According to Zhu Tao, director of the Aviation Safety Office of the Civil Aviation Administration, the technical investigation team has repeatedly demonstrated according to the on-site investigation results in recent days and more accurately determined the key search area of the flight data recorder (the second black box). The search and rescue team adjusted the on-site work plan according to relevant suggestions, graded the excavation points in the core area, dispatched resources according to priority, improved the search efficiency, increased the working hours of a single day and carried out night search operations while increasing the construction and survey strength of the excavation site. Zheng Xi, chief of Guangxi fire rescue corps, said that in the early morning of the 27th, they sent 338 fire rescue workers to the scene to search, of which 160 went deep into the core area. "In order to improve the search efficiency, we adopt the way of cooperating with civil aviation experts. According to the mode of five fire rescue personnel and one civil aviation expert, we divide the grid around key areas and carry out operations in multiple groups simultaneously." What's the use of flight data recorder decoding? Zheng Xi said that after inspection, other parts of the flight data recorder were seriously damaged, and the appearance of the data storage unit was relatively intact. At present, the recorder has been sent to Beijing professional laboratory for decoding. The data in the flight data recorder can provide real and objective evidence for the analysis of the cause of the accident. In the later stage, the investigators need to combine the data of the two recorders, the evidence of on-site investigation, air traffic control radar data, land air communication between the crew and the air traffic control unit, data link transmission information between the aircraft and the ground, witness interview and other information for comprehensive analysis and judgment, In order to analyze the cause of the accident more objectively and accurately. On the 27th, the reporter saw at the core scene of the accident that the staff were still continuing to search and obtain evidence. Mao Yanfeng, director of the civil aviation bureau's accident investigation center, said that after the completion of the field investigation, the investigation team will combine all the information and data obtained from the preliminary investigation, combined with the experimental verification conclusions, make full analysis and judgment, and reveal the causes of the accident. What's the difference between the two black boxes on the plane? Mao Yanfeng introduced that the aircraft is generally equipped with two black boxes, namely flight data recorder and cockpit voice recorder. The outer surfaces of the two recorders of the crashed aircraft are orange, which is very eye-catching, easy to search and find, and can resist high overload impact, high temperature, seawater immersion and other characteristics. They are not easy to be damaged. They can help analyze the aircraft status, crew operation and the situation in the cockpit after the accident. The flight data recorder is installed at the rear of the cabin. The recording time is about 25 hours and the recording parameters are about 1000. It records the important parameters of the aircraft, such as altitude, speed, heading, pitch angle, roll angle and vertical speed. It starts to record when the engine is started and stops after the engine is stopped. The first black box previously found is the cockpit voice recorder, which is generally installed at the rear of the cargo hold and can record the sound of four channels, namely the captain channel, the co pilot channel, the standby channel and the environment channel, with a recording time of two to three hours. (Xinhua News Agency)