Indonesian Report on 737 Max Crash Blames Faulty Boeing Design and Lion Air Staff

Indonesia's National Transportation Safety Committee released the report on Friday.
Fabienne Lang

The devastating and fatal Lion Air crash in October last year prompted Indonesia's aviation safety agency to look into the situation. A close examination of the new Boeing 737 Max 8 aircraft that was used, as well as any other potential issues, were taken into account. 

Last Friday, the agency published their report, stating the Boeing's MCAS flight control system, Lion Air staff misjudgment, and a faulty sensor supplied by a Florida company were all partly to blame. 


The crash and the errors

October 29, 2018, saw all 189 passengers and crew onboard Lion Air's Boeing 737 Max 8 flight departing from Jakarta crash into the Java Sea. There were no survivors. 

Unfortunately, just five months later, another Boeing 737 Max 8 aircraft crashed, this time operated by Ethiopian Airlines, and 157 lives were lost. 

The Indonesian National Transportation Safety Committee (KNKT) was able to find nine factors that assisted in leading to the crash. The Committee mostly pointed the blame towards Boeing's MCAS, which is a feature only belonging to the 737 Max 8 aircraft.

If the MCAS finds that the aircraft's nose is too high, it pushes the aircraft's nose down automatically by using control surfaces on the plane's horizontal tailplane. 

"The MCAS function was not a fail-safe design and did not include redundancy," the report said.

Lion Air staff were also partly to blame. During the 10-minutes, when the plane was oscillating, they were unable to regain control of the aircraft. The pilots were unable to determine their airspeed and altitude. 

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As soon as the pilots pulled the nose of the plane, the MCAS pushed it back down.

Indonesian Report on 737 Max Crash Blames Faulty Boeing Design and Lion Air Staff
Boeing has issued this comment on their website. Source: Boeing

Some of the report's main points

The 322-page report highlighted many points in detail. Nine factors appear to have been the downfall of the 737 Max 8. 

A few of these points are as follows: 

  • The 737 MAX has a warning light that would have shown that the faulty sensor was disagreeing with the working sensor on the other side of the aircraft's nose. But a software bug meant that the warning light was working only if Lion Air has purchased a package of equipment Boeing sold only as an option.
  • As had previously been found, 737 MAX flight crews were inadequately trained on using MCAS, how to react when a malfunction occurred, and how to deactivate MCAS if needed. "Not including information about the MCAS from the flight crew operating manual and flight crew training made it more difficult for the flight crew to diagnose problems and find the corrective actions to overcome the situation," the report said.
  • The pilots who'd flown the doomed aircraft the day before also experienced problems controlling the MCAS, but didn't give a full report on the conditions they experienced upon landing or how they mitigated them. 
Indonesian Report on 737 Max Crash Blames Faulty Boeing Design and Lion Air Staff
Lion Air plane landing. Source: PK-REN/Flickr

Boeing has grounded its 737 Max 8 planes globally. The company's CEO, Dennis Muilenburg, said that it will be "addressing" the KNKT's safety recommendations.

"We commend Indonesia's KNKT for its extensive efforts to determine the facts of this accident, the contributing factors to its cause and recommendations aimed toward our common goal that this never happens again," said Muilenburg.

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