China reinforces tight control over Eastern Airlines Boeing plane crash mystery

China's ruling Communist Party moved to control information, revving up its censorship machine as media outlets and local residents raced to the crash site

The cause of China's deadliest air crash in decades remains a mystery, with authorities giving a few details in a preliminary report on April 20 while enforcing strict censorship one month after the disaster.

In the immediate aftermath of the crash, China's ruling Communist Party moved quickly to control information, revving up its censorship machine as media outlets and local residents raced to the crash site.

It has maintained its tight grip over the narrative, with the preliminary probe leaving key questions unanswered. China Eastern flight MU5375 was travelling from Kunming to Guangzhou last month when it inexplicably plunged from an altitude of 29,000 feet into a mountainside, killing all 132 people on board.

Beijing was required to submit a preliminary report to the International Civil Aviation Organisation within 30 days. According to that report, investigators found no evidence of "anything abnormal", the country's Civil Aviation Administration (CAAC) said on April 20.

The regulator has indicated, however, that it will not make the preliminary report available to the public and a full investigation may take years. In a statement, the CAAC said staff had met safety requirements before takeoff, the plane was not carrying dangerous goods and did not appear to have run into inclement weather.

No reasoning was given as to why the plane abruptly dropped out of the sky, nor were details shared about the two flight trackers or "black boxes" that were recovered.

The devices — a cockpit voice recorder and a flight data tracker — are being analysed at an American lab with the help of the U.S. government investigators. The crash was China's deadliest in around 30 years and dented the country's otherwise enviable flight safety record.