Chinese investigators have completed a preliminary report into the March 21 crash of a China Eastern Airlines Boeing 737-800.
The Civil Aviation Administration of China (CAAC) is required under provisions of the International Civil Aviation Organization (ICAO), to send the initial report to ICAO and participating countries within 30 days of the incident.
While shedding little light on the potential causes of the crash which killed all 123 passengers and nine crew, the document confirms various factual details such as flight history, crew and maintenance personnel, airworthiness maintenance and wreckage distribution.
Investigators confirmed the aircraft, B-1791 (c/n 41474), took off from runway 21 of Kunming Changshui Airport at 1.16pm Beijing time and climbed to an altitude of 29,200ft (8,900m) by 1.27pm. Just under an hour later at 2.17pm, it entered Guangzhou control area along the A599 route.
At 2.20pm, air traffic controllers observed an altitude deviation as the aircraft left its assigned cruise level. According to the report, the controller called the crew immediately but received no reply.
Less than a minute later, the last radar return was recorded showing the jet at 11,089ft (3,380m), with a ground speed of 545kt (627mph) and a heading of 117 degrees.
The accident site spans approximately 45 square meters and has a depth of 2.7m. According to the CAAC, the debris of the aircraft wreckage was mainly found on the ground and underground in the azimuth range of 0° to 150° of the impact point. The trailing edge of the right wingtip winglet was found approximately 7.5 miles (12km) from the crash site.
Major parts of wreckage including the horizontal stabiliser, tail, rudder, both engines and wings, fuselage, landing gear and cockpit parts were found at the scene.
Investigators confirmed the qualifications of the flight crew, cabin crew and maintenance personnel met the legal requirements, and that the airworthiness certificate of the accident aircraft was valid.
No faults were reported before the flight and no cargo declared as dangerous goods were on the aircraft. The CAAC said the two flight recorders were severely damaged due to the impact and that data restoration and analysis work was still in progress.
The jet – which was delivered new to the Chinese airline in 2015 – was a popular sight at airports as it was adorned with a special peacock livery.
The March 21 crash was the worst aviation disaster the country has seen in more than a decade. China Eastern has only had one major air disaster before. On November 21, 2004, Flight MU 5210 from Baotou, Inner Mongolia to Beijing/Capital, and onwards to Shanghai/Hongqiao, rapidly lost altitude just moments after take-off. The Bombardier CRJ-200 crashed through a residential area and came to rest in a lake close to the airport, killing all 53 people onboard, plus a further two on the ground. Investigators of the 2004 tragedy concluded that inadequate de-icing at Baotou was to blame.
Chinese authorities did not specify when they expect to complete follow-up work but said the technical investigation team would continue to carry out in-depth investigations into wreckage identification, classification and inspection, flight data analysis and experimental verification in order to “rigorously identify the cause of the accident”.