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.
A Boeing spokesman said in a statement on Monday that the company continued “to extend our heartfelt sympathies to the families and loved ones of Ethiopian Airlines Flight 302.”
“Boeing continues to provide technical assistance in support of the investigation, at the request of and under the direction of the U.S. National Transportation Safety Board,” the statement read. “We look forward to reviewing the full details and formal recommendations that will be included in the final report from the Ethiopian Accident Investigation Bureau.”
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 of 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 in an interview, though Ethiopian has insisted that its pilots were familiar with warnings issued by the U.S. Federal Aviation Administration after the Lion Air crash.
Asked about recent comments by Boeing’s new chief executive, David L. Calhoun, suggesting that pilots in Ethiopia and Indonesia had far less experience than those in the United States, Mr. Zeggeye said, “We have this joke that we usually say, ‘If a plane crash does not kill you, the report will kill you.’ It’s always easy to blame the pilots.”
Last week, a preliminary report by the U.S. House Committee on Transportation and Infrastructure said that production pressures and a “culture of concealment” at Boeing had contributed to both plane crashes. The report also found a conflict of interest with regard to oversight, highlighting instances in which Boeing employees responsible for representing the F.A.A.’s interest “failed to take appropriate actions” to safeguard passengers on commercial flights.
The aftermath of the Ethiopian crash highlighted the sizable influence that Boeing has over regulators and oversight procedures, said Githae Mwaniki, an aviation expert with Aviation Information Consultants in Nairobi, Kenya.
“That whole area of certification and modification of existing aircraft requires a total overhaul,” Mr. Mwaniki said.
In light of findings in the House committee’s report that Boeing engaged in cost-cutting and fast-tracked the production of the 737 Max to compete with Airbus, some families are seeking punitive damages against the company.
Boeing is also facing a class-action lawsuit in a U.S. court on behalf of more than 7,000 Max pilots who argue that the company’s practices put the lives of pilots, crew members and passengers at risk.
But even as they awaited their day in court, victims’ families gathered in Ethiopia this week to remember their loved ones.
Esther Wanyoike of Kenya, whose 29-year-old brother, George, died in the crash, said by telephone from Addis Ababa on Monday that the family hoped to create a foundation in his name to help finance community projects in their area. The family is among those suing Boeing.
“We want to make sure this doesn’t happen again,” Ms. Wanyoike, a lawyer, said of the crash that killed her brother, who worked as an engineer with General Electric in Nairobi.
“We are here in Ethiopia to do the last walk with our loved ones,” she said. “But if we can push Boeing to make planes safer for all, that would be a bit of justice.”
Simon Marks reported from Addis Ababa, and Abdi Latif Dahir from Nairobi, Kenya.