Boeing 737 Max Lion Air crash caused by series of failures

A series of failures led to the crash of a Lion Air flight, which killed 189 people and led to the grounding of the Boeing 737 Max, a report has found.

Investigators said faults by Boeing, Lion Air and pilots caused the crash.

Five months after the disaster in October last year, an Ethiopian Airlines plane crashed, killing all 157 people on board, which led to the grounding of the entire 737 Max fleet.

Faults with the plane’s design have been linked to both crashes.

On Friday, air crash investigators in Indonesia released their final report, detailing the list of events that caused the Lion Air jet to plunge into the Java Sea.

“From what we know, there are nine things that contributed to this accident,” Indonesian air accident investigator Nurcahyo Utomo told reporters at a news conference.

“If one of the nine hadn’t occurred, maybe the accident wouldn’t have occurred.”

What does the report say?

The 353-page report found the jet should have been grounded before departing on the fatal flight because of an earlier cockpit issue.

However, because the issue was not recorded properly the plane was allowed to take off without the fault being fixed, it said.

Further, a crucial sensor – which had been bought from a repair shop in Florida – had not been properly tested, the report found. On Friday, the US aviation regulator revoked the company’s certification.

The sensor fed information to the plane’s Manoeuvring Characteristics Augmentation System – or MCAS. That software, which is designed to help prevent the 737 Max from stalling, has been a focus for investigators trying to find the cause of both the Lion Air and Ethiopian Airlines crashes.

Indonesian investigators identified issues with the system, which repeatedly pushed the plane’s nose down, leaving pilots fighting for control.

It showed there were incorrect assumptions about how the MCAS control system would behave and that the “deficiencies” had been highlighted during training.

Further, the report found that the first officer, who had performed poorly in training, struggled to run through a list of procedures that he should have had memorised.

He was flying the plane just before it entered into the fatal dive, but the report said the captain had not briefed him properly when he handed over the controls as they struggled to keep the plane in the air.

The report also found that 31 pages were missing from the plane’s maintenance log.

Indonesian investigators have previously said mechanical and design problems were key factors in the crash of the Lion Air plane.

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This report describes a catalogue of failures – from poor communication to bad design to inadequate flying skills – which culminated in the deaths of 189 people.

There are lots of what-ifs here. If the crew of the previous days flight had given a more detailed description of the problems they’d faced, the aircraft might never have taken off on its fatal flight. And if the captain, who’d successfully kept the plane in the air – despite the intervention of a rogue automated system he didn’t understand – hadn’t handed over to his less-capable first officer, disaster might still have been avoided.

As Boeing’s chief executive Dennis Muilenburg has repeatedly stated, there was a chain of events. But at the heart of that chain was MCAS – a control system that the pilots didn’t know about, and which was vulnerable to a single sensor failure.

Boeing – and regulators – allowed the system to be designed in this way and didn’t change it after the Lion Air crash, leading to a further disaster. And that means that while the report clearly points to serious failures by a parts supplier and by the airline itself, it is Boeing that will bear the greatest share of responsibility.