Boeing Max design faulted in Lion Air crash, Indonesia says

Flaws in the design of Boeing Co.’s 737 Max and lack of information on how to deal with malfunctions in one of the jet’s flight-control systems contributed to last year’s crash of Lion Air Flight 610, which killed 189 people, Indonesian investigators found.

In a slideshow to victims’ families, the National Transportation Safety Committee said the 737 Max’s Maneuvering Characteristics Augmentation System, or MCAS, was approved based on incorrect assumptions and that its reliance on a single angle-of-attack sensor made it vulnerable. It also criticized the certification process of the plane.

Indonesia is expected to release its final report in the coming days on the disaster that occurred just under a year ago, on Oct. 29, 2018. The controversial MCAS system, which activates when the plane appears to be at risk of stalling, was also implicated in an Ethiopian Airlines crash in March that claimed 157 lives.

The NTSC’s findings could influence regulators worldwide as they assess the fate of Boeing’s best-selling plane. The jet has been grounded globally since March 13, costing the Chicago-based company over $8 billion. The head of its jetliner division stepped down Tuesday after less than three years in the job.

Wednesday’s presentation in Jakarta indicated that the lack of guidance on MCAS made it harder for crews to respond to automated actions by the system, while a replacement sensor installed on the plane wasn’t properly calibrated during an earlier repair, and that this error hadn’t been detected. A lack of documentation made it more difficult for maintenance and accident crews to take appropriate actions, a slide showed.

The findings suggest a design flaw with the plane, said Satyendra Pandey, a New Delhi-based independent analyst and former head of strategy at Go Airlines India Ltd. “Going back to revisit the design itself has tremendous ramifications for Boeing - both in terms of cost and liability,” he said. “It can be assumed that Boeing will contest this and point to software as the flaw.”

A Boeing representative wrote in an email that it was too premature to comment on the report as it hasn’t been officially released by Indonesian investigators. Lion Air didn’t immediately respond to calls seeking comments.

MCAS is a feature installed on the 737 Max that automatically pushes the plane’s nose downward if it detects danger of an aerodynamic stall. Recently published messages between two senior Boeing test pilots show they had misgivings about the system during the jet’s certification in 2016, with one describing it as egregious.

The U.S. Federal Aviation Administration, which has faced criticism for approving the feature and giving Boeing too much authority to oversee itself, said Friday that it was concerned by comments in the messages between the two pilots and chastised Boeing for not sharing the information sooner. Boeing said it told regulators it had expanded the role of the flight-control software.

Problems with the three-month-old Lion Air jet’s sensors had been reported on three previous flights, including one made from Bali the day before the crash. In that instance, an off-duty pilot traveling in the cockpit identified the problem and told the crew how to disable the malfunctioning control system. However, the pilots didn’t report key issues with the flight after they landed.

A different crew was on board the following day. Flight 610 took off from Jakarta at 6:20 a.m. on the Monday Oct. 29, heading to the tourist destination of Pangkal Pinang, off Sumatra’s east coast. About 13 minutes later, it plunged into the sea after the pilots - an Indian and Indonesian - were unable to regain control in a battle with the controls to keep the aircraft from repeatedly diving.

This was Indonesia’s deadliest airline crash since 1997 and reignited worries about the country’s aviation safety record. The nation’s airlines, including Lion Air, were banned from flying to the European Union and the U.S. for almost a decade until 2016 because of safety concerns.

Boeing Chief Executive Officer Dennis Muilenburg is due to face questions from lawmakers in Washington in less than two weeks. The company was hit with a lawsuit earlier this month demanding records that will allegedly show if mismanagement is to blame for safety issues leading to the grounding of the 737 Max fleet. Boeing is due to report quarterly results ahead of Wednesday’s market open in New York.