JAKARTA, Indonesia — Indonesian investigators found plenty of blame to go around for a Boeing 737 Max crash that killed 189 people a year ago.
They faulted design decisions by Boeing that made the plane vulnerable to failure of a single sensor. They criticized U.S. safety regulators who certified the plane. And they pointed fingers at one of their country’s own airlines, Lion Air, for inadequate pilot training and maintenance lapses. Investigators said in a report issued Friday that a combination of nine main factors doomed the Boeing jet that plunged into the Java Sea shortly after takeoff on Oct. 29, 2018.
“If one of the nine hadn’t occurred, maybe the accident wouldn’t have happened,” chief investigator Nurcahyo Utomo said at a news conference.
Release of the final report is likely to put more pressure on Boeing, which is under investigation by the Justice Department and Congress. Boeing is still working to fix its best-selling plane seven months after all Max jets were grounded following a second crash on March 10 in Ethiopia, which killed 157 people. The final report on that accident is several months away, but preliminary findings highlighted remarkable similarities to the disaster in Indonesia.
Takeaways from the Indonesian report:
• Boeing’s design of a critical flight-control system was a key factor in the crash, repeatedly pushing the plane’s nose down. The system, called MCAS, relied on a single sensor to measure direction of air flow, making it vulnerable if the sensor misfired — which it did. Boeing also made incorrect assumptions about how quickly pilots could respond to a malfunction and didn’t inform pilots of the existence of MCAS until after the Lion Air crash, making it harder for Lion Air’s pilots to save the plane and its passengers.
• Lion Air pilots who experienced problems on a previous flight failed to properly note it in the plane’s log, so maintenance crews couldn’t make necessary repairs. Pilots on the fatal flight failed to perform the correct emergency procedure for a nose-down pitch of the plane. The co-pilot failed to understand the situation and was preoccupied running the wrong emergency checklist.
• Oversight by safety regulators who certified the plane could have been much better. A malfunction of MCAS was considered a “major” safety issue but not “hazardous” or “catastrophic” — classifications that would have prompted a deeper review. Boeing assumptions about how quickly pilots would respond to a problem proved too optimistic, but they met Federal Aviation Administration guidance.
