Crash report points to Boeing, maintenance

Lion Air faulted for inadequate pilot training

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 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 brandnew Boeing jet that plunged into the Java Sea shortly after takeoff 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.

Many of the problems had been previously disclosed in a preliminary report that Indonesian authorities issued last year and in recent findings by U.S. and global safety experts.

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.

Some key takeaways:

■ Boeing’s design of a critical f light-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 f low, 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.

■ Lion Air pilots who experienced problems on a previous f light failed to properly note it in the plane’s log, so maintenance crews couldn’t make necessary repairs. Pilots on the fatal f light failed to perform the correct emergency procedure for a nose-down pitch of the plane. The copilot 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.

Budget carrier Lion Air’s f light 610 had only been f lying for two months but began having problems a few days before the crash. A new “angle-of-attack” sensor, which measures the plane’s direction relative to oncoming air, was installed while the aircraft was on Bali a day before the crash. The sensor wasn’t properly calibrated during an earlier repair, leaving it out of alignment, and might not have been tested correctly.

On a f light the day before the crash, pilots were bombarded by warnings about airspeed, altitude and an impending stall.

The captain and co-pilot regained control of the plane by manually overriding the automated system with help from a third Lion Air pilot who was hitching a ride in the cockpit jump seat.

The plane made it to Jakarta safely, but pilots did not fully report the problems they had experienced.