UPDATE: Boeing design, pilots and maintenance faulted in Lion Air crash
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 spread the blame among Boeing, the US Federal Aviation Administration, Lion Air’s maintenance crew and the pilots themselves.
“The design and certification of the MCAS (Manoeuvring 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 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.
The report also said Boeing failed 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.
Among the recommendations the report made were calls 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. Earlier this week, the families of the Lion Air crash victims were told mechanical and design issues contributed to the crash of a Lion Air 737 MAX jet last October, Indonesian investigators told victims’ families in a briefing on Wednesday (Oct 23) ahead of the release of a final report.
Details of the report were released earlier to the families of the crash victims in a special briefing. Those details included the fact that incorrect assumptions on how the MCAS system worked and how pilots would react. Slides shown at the briefing said a lack of documentation about how systems would behave in a crash scenario, including the activation of a “stick shaker” device that warned pilots of a dangerous loss of lift, also contributed. “Deficiencies” in the flight crew’s communication and manual control of the aircraft contributed as well, the slides showed, as did alerts and distractions in the cockpit. The deficiencies had been “identified during training,” the slides said, without elaborating.
Some relatives of the victims at the briefing in Jakarta expressed disappointment that direct responsibility wasn’t assigned. “Why isn’t the airline heavily sanctioned?” said Anton Sahadi, 30, whose relatives Riyan Aryandi and Muhammad Rafi Andrian were killed in the crash. “This isn’t about one or two lives, it’s about 189 lives.”
The 737 MAX was grounded worldwide after a second deadly crash in Ethiopia in March 2019. Plane maker Boeing is under growing pressure to explain what it knew about 737 MAX problems before the aircraft entered service. Boeing has already said it would redesign the MCAS anti-stall system to rely on more than a single sensor and to help reduce pilot workload.
Boeing reportedly has already settled the first claims stemming from the Lion Air crash, a US plaintiffs’ lawyer said and Reuters reported that families of those killed will receive at least US$1.2 million each. The manufacturer faces nearly 100 lawsuits over the Ethiopian Airlines crash on Mar 10, which killed all 157 people on board the flight from Addis Ababa to Nairobi.
The 737 MAX was grounded following the second crash, leaving Boeing and the US Federal Aviation Administration (FAA) grappling to contain a crisis that has left 346 people dead, forced airlines to ground more than 300 aircraft, and put Boeing deliveries worth more than US$500 billion on hold.
Boeing has also ousted the top executive of its commercial airplanes division, Kevin McAllister, marking the first high-level departure from the plane maker since two fatal crashes and earlier stripped CEO Dennis Muilenberg of his chairman’s post.
In response to the report, Boeing CEO Muilenburg said “on behalf of everyone at Boeing, I want to convey our heartfelt condolences to the families and loved ones of those who lost their lives in these accidents. We mourn with Lion Air, and we would like to express our deepest sympathies to the Lion Air family. We commend Indonesia’s National Transportation Safety Committee 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.”
Boeing also said that since this accident, the 737 MAX and its software are undergoing an “unprecedented level of global regulatory oversight, testing and analysis. This includes hundreds of simulator sessions and test flights, regulatory analysis of thousands of documents, reviews by regulators and independent experts and extensive certification requirements”.
“Over the past several months Boeing has been making changes to the 737 MAX. Most significantly, Boeing has redesigned the way Angle of Attack (AoA) sensors work with a feature of the flight control software known as Manoeuvring Characteristics Augmentation System (MCAS). Going forward, MCAS will compare information from both AoA sensors before activating, adding a new layer of protection. In addition, MCAS will now only turn on if both AoA sensors agree, will only activate once in response to erroneous AOA, and will always be subject to a maximum limit that can be overridden with the control column.”
Boeing also said it was updating crew manuals and pilot training, designed to ensure every pilot has all of the information they need to fly the 737 MAX safely.