Investigators will probe what caused one of the safest airplanes to crash in China

Aviation experts say the jetliner that crashed Monday in the South China mountains was one of the safest in the world, which could raise questions about one of the industry’s workhorses, the Boeing 737-800 NG.

China Eastern Airlines Flight 5735 crashed in the mountains of southern China, leaving the fate of its 132 passengers and crew members unknown. Investigators are likely to use flight recordings and the final minutes of air traffic control communication to determine what caused the crash.

The plane lost contact over Wuzhou during a flight between the southern cities of Kunming and Guangzhou, the airline and the country’s Civil Aviation Administration said. The latter is leading the investigation.

“They will be looking for the flight data recorder and the voice data recorder from the crash site, because they hold vital information to really know what occurred during the last moments before the aircraft’s descent. That will be important,” said Hassan Shahidi, the president of the Flight Safety Foundation, a nonprofit organization that promotes aviation safety.

Investigators also will delve into the maintenance history of the aircraft and its engine, the recent training of the flight crew and the pilot’s experience, he said.

Shahidi said investigators also will want to know the communications between the pilot and air traffic control in the minutes leading up to the crash.

Before Monday’s crash, the 737-800 NG, or Next Generation, was considered among the safest aircraft in operation. The fleet has recorded only 11 fatal accidents out of more than 7,000 plans that have been delivered since 1997, according to the aviation consultancy Cirium.

More than 4,200 of the planes are in passenger service, about 17 percent of the world’s fleet, according to the group. Of those, there are 1,177 in China. All four major US carriers operate the aircraft, Cirium said.

“The 737 NG has been in operation for 25 years and has an excellent safety record,” said Paul Hayes, Cirium’s director of air safety and insurance.

The 737-800 NG’s recent safety record appears to stand in contrast to that of the Boeing 737 Max 8, which was banned from the skies worldwide in March 2019 after two crashes killed more than 300 people.

Lion Air Flight 610 crashed in October 2018 in Indonesia, killing 189 people. Five months later, all 157 people aboard Ethiopian Airlines Flight 302 died when it crashed shortly after takeoff.

A new version of the plane eventually returned and completed its first US commercial flight in December 2020.

“We’ve been engaged with the FAA, with Boeing, with everybody that’s associated with the aircraft to ensure that safety is held at the highest level,” Robert Isom, the president of American Airlines, said at the time when the American Airlines flight was set to depart from Miami to New York City, NBC News reported. “This aircraft has been checked out from top to bottom.”

Monday’s crash may renew those safety concerns. The National Transportation Safety Board, which has appointed a senior air safety investigator to represent the US in the investigation, said representatives from Boeing, the Federal Aviation Administration and the plane’s engine maker, CFM, will serve as technical advisers.

“Our thoughts are with the passengers and crew of China Eastern Airlines Flight MU 5735,” Boeing said in a statement. “We are working with our airline customer and are ready to support them.”

The flight left Kunming at 1:11 pm (1:11 am ET), with a scheduled arrival time less than two hours later, according to data from the flight-tracking website FlightRadar24. It showed that the aircraft rapidly lost altitude while it was cruising just over an hour into the flight, descending from 29,000 feet in a matter of minutes to its last tracked position.

Judging by how rapidly the plane dropped, the pilot was no longer in control, said Willie L. Brown Jr., a pilot and associate professor of aviation at the University of Maryland Eastern Shore.

In addition to dissecting the plane’s history, Brown said, investigators will try to determine what role, if any, the weather and the mountainous region may have played.

“In general, I would try to find out what the structural integrity of the aircraft was,” Brown said. “It could be anything.”

Experts say it will take some time to figure out what caused the aircraft to go down.

“At this point, it’s really too early,” Shahidi said. “There are a number of things that might have gone wrong, but the only way to figure it out is through data and information.”