Indonesian investigators found scores of problems and missteps in connection with last year’s fatal Lion Air crash, ranging from design flaws in Boeing Co’s 737 MAX airplane to certification failures by the US regulator and pilot errors.
In a much-anticipated report released yesterday, the National Transportation Safety Committee listed its findings and recommended fixes to Boeing, Lion Air and aviation authorities in the US and Indonesia. A significant amount of the focus centred on a flight-control feature called the Maneuvering Characteristics Augmentation System, which has also been implicated in an Ethiopian Airlines crash in March.
The extent that investigators faulted Boeing may add pressure on regulators to intensify scrutiny of its best-selling plane, which has turned into one of its worst crises and undermined the credibility of the US Federal Aviation Administration. While this closes one chapter on the saga, it’s not over. Boeing chief executive officer Dennis Muilenburg, who was stripped of his role as chairman earlier this month, is due to face questions from lawmakers in Washington next week.
The 737 MAX was grounded soon after the crash in Ethiopia, costing Boeing $9.2bn and weighing on the Chicago-based company’s outlook. While Boeing says it has made significant progress in returning the 737 MAX to service, no date has been set.
In response to the findings, Boeing CEO Muilenburg said the company is addressing the Indonesian investigator’s safety recommendations. Boeing engineers have been working with the FAA and other regulators to make software updates and other changes, according to the statement.
The FAA said it welcomed the recommendations from Indonesia and would carefully consider them in its review of the 737 MAX. “The aircraft will return to service only after the FAA determines it is safe,” it said in an emailed statement. Lion Air said in a statement it’s “essential to determine the root cause and contributing factors to the accident and take immediate corrective actions to ensure that an accident like this one never happens again.”
Minutes after taking off for Pangkal Pinang on the morning of October 29, Lion Air Flight 610 nosedived into the Java Sea, killing all 189 people on board. It was the second-deadliest airline disaster in Indonesia’s aviation history, following a 1997 crash near Medan that killed 234 people.
During testing, Boeing determined that malfunctions involving MCAS weren’t deemed serious enough — hazardous or catastrophic failures — for a more rigorous analysis, which could have identified significant problems with its design, according to excerpts of the NTSC report seen earlier by Bloomberg. Boeing also erroneously assumed that the crew would be able to correctly deal with malfunctions within three seconds, even though they were unaware of the existence of the flight-control system, it said.
“The flight crew should have been made aware of MCAS which would have provided them with awareness of the system and increase their chances of being able to mitigate the consequences,” the report said. “Training would have supported the recognition of abnormal situations and appropriate flight crew action.”
During simulator testing, Boeing never considered a scenario that occurred in the Lion Air flight, where the flight-control system kicked in multiple times, pushing down the plane and resulting in thresholds being crossed. The Lion Air crew reacted differently to what Boeing anticipated, according to the report.
Indonesian investigators also highlighted some problems in the certification process of the 737 MAX, saying the aircraft manufacturer didn’t submit required documentation and the Federal Aviation Administration didn’t adequately oversee the overall design.
Meanwhile, Boeing has handed final documents for a software fix to the FAA, and is preparing for a certification flight. It said this week it still expects regulatory clearance during the fourth quarter to return the 737 MAX to service. Approvals in other regions are likely to come after. In Europe, regulators plan to do their own flight tests, though they’ve said they’ll try to keep any delays as short as possible.
Airline customers have been cautious on the MAX’s return. Southwest Airlines Co’s CEO said on Thursday he isn’t sure whether the FAA will sign off this year, and after that it will take as long as two months to train pilots and get aircraft ready to fly. Norwegian Air Shuttle ASA said this week it expects the MAX to remain idle until at least late March.
And while the likes of India’s aviation-safety regulator have said that Boeing has already addressed many of the concerns raised by Indonesian investigators, some indicated Boeing still has a long way to go.
“The fundamentals of the MAX was that an over-sized, over-powerful engine was loaded on an air-frame that really couldn’t take it,” said Mark Martin, founder of Dubai-based Martin Consulting LLC. “This is an inherent design flaw. The software update Boeing has proposed isn’t going to be acceptable to airlines, pilots and regulators across the world.”
Boeing will likely have to install a modification kit in every 737 MAX — each costing as much as $15mn — Martin said, adding that he doesn’t see the plane flying for another year. “That’s not really a lot of money, but it’s Boeing who has to pay for this.”
Back in Indonesia, the NTSC presented a slideshow summarising its findings to families of the Lion Air crash victims in Jakarta on Wednesday. It said the MCAS was overly reliant on a single angle-of-attack sensor, making the system vulnerable if the sensor malfunctioned. The investigation found that a replacement sensor installed on the doomed Lion Air plane wasn’t calibrated properly during the repair.
Incorrect assumptions were made about how pilots would response to malfunctions while designing the 737 MAX and getting it certified
MCAS relied on one sensor based on false assumptions.
MCAS was vulnerable to errors as it relied only on a single angle-of-attack sensor.
Pilots found it more difficult when the MCAS activated without command, as they were not trained on the system.
A key alert wasn’t correctly enabled during the 737 MAX’s development
The angle-of-attack sensor installed on the crashed plane wasn’t calibrated correctly during an earlier repair.
The improper calibration of the sensor wasn’t detected.
Previous instances of warnings of an immediate stall weren’t documented in flight and maintenance logs. The lack of information prevented maintenance crew and accident crew from taking appropriate action
Multiple alerts, MCAS activation, air-traffic-control communication and manual flying were not managed well
According to the report seen by Bloomberg, the problems with flight-data readings were initially detected on an October 26 flight from Tianjin in China to the Indonesian city of Manado. An examination of the angle-of-attack sensor showed it became unreliable in cold temperatures. An engineer in Manado suggested the crew continue to Denpasar in Bali for repairs.
“This indicated that the aircraft was released with known possible recurring problem,” the report said.
On a flight from Denpasar the day before the crash, the crew on the 737 MAX ignored malfunctioning indicators, according to the NTSC. It said the pilot was confident about continuing because the aircraft was controllable and the weather along the route was good. The decision to keep flying was “highly unusual” after getting warnings for an imminent stall, according to the report.
Previous reports have shown that an off-duty pilot travelling in the cockpit of that flight helped disable the malfunctioning control system. According to the NTSC report, the captain had asked for the deadheading flight crew’s assistance, and kept the fasten seat-belt sign on.
“These actions indicated that the captain was aware of the need to use all available resources to alleviate the matter to complete the flight to the destination,” it said.
The problems encountered weren’t properly detailed in the post-flight report, which was filed outside office hours and not processed until the following day, the NTSC said in the report. “The incomplete report became a hazard as the known or suspected defects were not reported which might make the engineer unable to properly maintain the airworthiness of the aircraft.”
The doomed flight’s crew, who might not have been aware of the previous problems, failed to complete checks on the aircraft due to distractions from the flight system, increasing their stress levels, the report said. They also didn’t declare an emergency or asked for special handling, which would have helped to reduce their workload.
There seemed to be a lack of communication among the flight crew, with the captain not explicitly saying how much difficulty he was experiencing controlling the aircraft, it said. “Most of the components of effective crew co-ordination were not achieved, resulting in failure to achieve the common goal of flying the aircraft safely.
Before its release, both Lion Air and Indonesian regulators objected to investigators’ findings on the grounds that they received too much of the blame, people familiar with the matter said last month.
In its statement yesterday, Boeing said it has redesigned the way angle-of-attack sensors work with the MCAS so that the mechanism turns on if both sensors agree, activates once in response to erroneous readings, and be subject to a maximum limit that can be overridden with the control column. It said it is also updating crew manuals and pilot training.
Nurcahyo Utomo, head of the flight accident sub-committee at Indonesia’s National Transportation Safety Committee (KNKT), speaks during a news conference in Jakarta yesterday. The KNKT yesterday listed its findings and recommended fixes to Boeing, Lion Air and aviation authorities in the US and Indonesia.
