Indonesian aviation authorities said Friday that mechanical and design issues, combined with a lack of proper pilot training, were major contributors to the crash of a Lion Air Boeing 737 Max jet in October 2018.

The aircraft plunged into the Java Sea shortly after takeoff from Jakarta, killing all 189 people on board.

The final report by Indonesia's National Transportation Safety Committee said the first officer had shown "issues" handling the aircraft during training, and was unfamiliar with procedures.

Additionally, there were problems with communication between the pilots that were exacerbated by alerts and distractions in the cockpit leading up to the crash.

Read more: Boeing settles first lawsuit with 737 Max crash families

Investigators also found that sensors providing data to the aircraft's automatic anti-stall system had been calibrated improperly during maintenance, and said the jet should have been grounded by Lion Air after faults were found on earlier flights.

The system's reliance on one sensor made it vulnerable to erroneous input, investigators said. 

The report recommended closer scrutiny of automated control systems, and better designed alert systems in the cockpit.

"During the design and certification of the Boeing 737-8 (MAX) assumptions were made about pilot response to malfunctions which, even though consistent with current industry guidelines, turned out to be incorrect," the committee during a meeting with victims' families Wednesday. 

Read more: Boeing and FAA at fault over 737 MAX certification — report

Problems for Boeing

Following a second crash in March 2019 of an Ethiopian Airlines Boeing 737 Max under similar circumstances the entire 737 Max fleet was grounded worldwide. 

The newly designed aircraft was Boeing's best-selling model ever. Before the two crashes 350 were registered worldwide, with about about 5,000 on order.

Read more: Boeing crash: Can machines make better decisions than people?

In both crashes, the 737 Max's new anti-stall system called "MCAS" appeared to have pushed the plane's nose downward, overriding the pilot's control.

The MCAS had been designed to prevent the plane's nose from getting too high and causing the aircraft to stall. 

Boeing has already said it would redesign the anti-stall system to rely on more than a single sensor.

wmr/rt (Reuters, dpa)

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