ADDIS ABABA, Ethiopia — Ethiopian investigators have concluded in a new analysis that the March 2019 crash of an Ethiopian Airlines flight was caused by design flaws in the Boeing 737 Max plane and not by the performance of the airline or its pilots, adding to the scrutiny of the jet model that has been involved in two recent deadly crashes.
An interim report released on Monday by the Ethiopian Aircraft Accident Investigation Bureau comes almost exactly a year after Ethiopian Airlines Flight 302 went down shortly after departing Addis Ababa, killing all 157 people onboard. The crash occurred five months after a similar Max owned by Lion Air of Indonesia crashed minutes after takeoff, killing 189 people.
Although several factors have been cited in the two crashes, malfunctions related to automated software known as MCAS were listed as key in both accidents.
The two crashes thrust Boeing into the biggest crisis in its history, leading to the ouster of its chief executive, Dennis A. Muilenburg, and drawing government scrutiny over the design, development and certification of the 737 Max. The subsequent global grounding of the 737 Max, Boeing’s most popular passenger jet, and the halting of its production are projected to cost the company $18 billion.
Boeing did not immediately respond to a request for comment on Monday.
The Ethiopian investigators’ assessment differs from Indonesia’s final investigation report on the Lion Air crash. The Indonesian report cited a number of factors, including aircraft design, the flight crew’s response and a lack documentation on the plane’s flight and maintenance history.
In Ethiopia’s case, investigators found that the aircraft had “a valid certificate of airworthiness,” had no known technical problems before departure, and had weight and balance “within the operating limits.”
But they said faulty sensor readings and automatic commands that did not appear “on the flight crew operation manual” had left the crew unable to control the plane, resulting in the fatal crash. The report also said that Boeing’s reliance on a single sensor for the 737 Max “made it vulnerable to undesired activation.”
The interim assessment corresponds with a preliminary report that Ethiopia released last April, in which investigators said that the pilots had “repeatedly performed all the procedures provided” by Boeing to bypass the automated system.
After the crash, concerns surfaced that the plane’s captain had not practiced on a flight simulator for the 737 Max 8 — even though the airline had installed a simulator two months before the crash. The airline has denied those accusations, and Ethiopian officials insisted that the pilots had obtained the necessary license and qualifications.
Yet Ethiopian, Africa’s largest and most profitable carrier, has faced criticism for its handling of the crash, with some former employees saying that the company had prioritized growth and profit at the expense of safety.
In an interview with The Associated Press last year, a former chief engineer with the carrier, Yonas Yeshanew, accused the airline of fabricating documents and overseeing a culture of corruption and shoddy maintenance. Yeshiwas Zeggeye, the former head of the Ethiopian Airline Pilots Association, also criticized what he described as an inadequate response by the airline after the Lion Air crash, in October 2018.
“It was just business as normal,” he said, though Ethiopian has insisted that its pilots were familiar with warnings issued by the U.S. Federal Aviation Administration after the Lion Air crash.