Indonesia’s report on Lion Air 737 MAX crash faults Boeing design and FAA certification as well as airline’s maintenance and pilot errors
Oct. 24, 2019 at 4:20 pm Updated Oct. 24, 2019 at 4:22 pm
By Dominic Gates and Lewis Kamb
The final report by air accident investigators into the Lion Air crash of a 737 MAX in Indonesia that killed 189 people a year ago provides a devastating critique of the design and certification of Boeing’s new flight control system on the airplane.
It also apportions blame to Lion Air’s maintenance work and its pilots, as well as a Florida firm that supplied a component, according to an advance copy reviewed by The Seattle Times.
“The design and certification of the MCAS (Maneuvering Characteristics Augmentation System) did not adequately consider the likelihood of loss of control of the aircraft,” the report states. “A fail-safe design concept and redundant system should have been necessary for the MCAS.”
The report is due to be released Friday in Indonesia, around midnight Thursday in Seattle.
The report found that after Boeing changed the original MCAS design, increasing its authority to move the horizontal tail, or stabilizer, from 0.6 degrees to 2.5 degrees, “the higher limit caused a much greater movement of the stabilizer than was specified in the original safety assessment document.”
After that change, as first reported in the Seattle Times in March, the company’s Stabilizer System Safety Assessment for the Federal Aviation Administration was not updated in time, with the result that the “FAA would not be able to reassess the safety of the design change,” the report states.
It also criticizes a Boeing failure to detect a software error that resulted in a warning light on the MAX not working, as well as Boeing’s failure to provide pilots any information about the flight control system. Both failures contributed to the crew’s inability to understand what was happening, the report said.
“The absence of information about the MCAS in the aircraft manuals and pilot training made it difficult for the flight crew to diagnose problems and apply the corrective procedures.”
The report also found that a critical sensor, a second-hand unit repaired and supplied by a Florida company, was faulty, and it found strong indications that it was not tested during installation by Lion Air maintenance staff.
And though similar faults had occurred on the previous flight of the same airplane, Lion Air’s maintenance staff failed to ground the airplane, says the report.
The previous flight “that experienced multiple malfunctions was classified as serious incident and should have been investigated,” the report states.
The report also faulted the two pilots on Lion Air JT610, particularly the first officer, who was unfamiliar with procedures and had shown himself in training to have problems in handling the aircraft.
The first officer failed to follow a procedure to identify which of the two sides of the aircraft was showing the correct airspeed. If he had, a checklist would have told him he could turn on the autopilot, which would have stopped the nose-down movements of the errant flight control system.
And the report found the crew failed to coordinate their responses to multiple failures and alerts.
After the captain successfully countered the airplane’s nose-down movements more than 20 times, he handed over to the first officer who was under stress and proved unable to maintain control. Shortly after, the plane nose-dived into the Java Sea, killing all on board.
The report concludes with a long series of recommendations for all parties involved.
Among the recommendations for Boeing, it asks for:
- A fail-safe re-design of MCAS.
- Adequate information about MCAS to be included in pilot manuals and training
- Closer scrutiny in future of any system capable of taking over primary flight control actions from the pilot.
- Design consideration of the effect of all possible flight deck alerts and indications on pilot recognition and response.
- Larger tolerance in Boeing’s designs to allow operation by a diverse population of pilots.
More to come. This story will be updated.
Dominic Gates: 206-464-2963 or
[email protected]; on Twitter: @dominicgates.
Lewis Kamb: 206-464-2932 or
[email protected]; on Twitter: @lewiskamb.