BEIJING — The pilots met Chinese standards for flying a commercial jet. No problems were found with the aircraft before it took off. There was no dangerous cargo loaded on board. Communications with the aircraft appeared normal until the fatal dive.
A preliminary report released Wednesday by China’s aviation safety regulator hasn’t cleared up much of the mystery as to why a China Eastern jet suddenly dived in clear weather last month and crashed into a muddy hill, killing all 132 people on board. . The report mainly took stock of what was previously known about the crash.
“The investigation found that the flight crew and cabin crew on board, as well as maintenance and clearance personnel met the qualification requirements,” the report said. “Before it drifted off cruising altitude, there was nothing abnormal in the wireless communications between the crew and air control or in the flight commands.”
The report also suggested it could take some time to obtain more evidence from the plane’s two flight recorders. “The two recorders on the plane were badly damaged in the crash,” it said, “and data recovery and analysis continues.”
As a signatory to the Convention on International Civil Aviation, the Chinese regulator was required to prepare a preliminary report on Wednesday 30 days after the crash. But a summary statement from the regulator, the Civil Aviation Administration of China, put forward no theories to investigate why the plane, a Boeing 737-800, suddenly turned nearly vertical as it cruised at 29,000 feet, maintaining that position except for a brief moment. rise up about two-thirds of the way down to the ground.
Commercial jets are designed to be naturally stable from front to back during flight. They don’t fly nearly straight down at very high speed unless extreme force is continuously applied to the horizontal stabilizers on either side of the tail, aviation experts said in the days after the crash.
A mechanical failure or software error could cause the horizontal stabilizers to malfunction, or a pilot could deliberately force the aircraft to fly almost straight down. The report did not discuss these possibilities. But it was reported that important parts of the tail had been found in the crater the plane had left on a bamboo-covered hill.
The plane’s engines were also found there.
Earlier this month, Wu Shijie, a safety officer with the Civil Aviation Administration of China, warned of a plethora of theories about the crash that had spread online in China. Some of these theories suggest pilot suicide as the cause of the crash. In recent days, Chinese aviation authorities have stepped up checks on the health and mental wellbeing of pilots of commercial aircraft.
But Mr Wu said these measures to pilots should not be taken as a sign that the cause of the crash had been determined. “We still cannot draw a conclusion as to the cause and nature” of the crash, he told reporters, according to an official Chinese aviation news website.
China has tried to be open and comply with international standards for air crash investigations. It has sent both black boxes to the National Transportation Safety Board in Washington for analysis.
The NTSB also dispatched a team to the crash site in southern China to assist with the investigation. China allowed the team to enter the country without the usual quarantine of three weeks or more, allowing the visiting researchers instead to follow the “travel bubble” requirements used during the Beijing Winter Olympics. Those standards require daily PCR testing for Covid-19 and severely limit contact with Chinese citizens. The NTSB said on Wednesday that the team had returned to the United States on April 14.
Keith Bradsher reported from Beijing, and Chris Buckley from Sydney, Australia.