The crash of Lion Air Flight 610 in late October has put Boeing’s 737 MAX and its anti-stall MCAS system in the spotlight. Aviation analysts say the new system installed on the MAX variant is different from that on earlier 737 models and say Boeing did not make it clear in flight manuals or training material that the system had changed. Boeing has steadfastly defended the system specifically and the 737 MAX overall and said the plane remains safe to fly. Boeing however, is reportedly looking to implement a software update that would change the way the MCAS system operates.
Press reports from Seattle at the end of November said Boeing may change the MCAS software to prevent the anti-stall system from being activated by erroneous data from its sensors. Boeing’s software change could block the recently modified anti-stall system from continuously running until the plane hits its nose-down limit, according to the reports. The MCAS function would be disabled if the crew counteracted it by trimming or adjusting settings in the opposite direction.
Data from the Lion Air flight recorder suggests the pilots sought to correct the system more than two dozen times before the jetliner plunged into the Java Sea on 29 October, killing all 189 people on board.
Boeing declined comment on the proposed changes, but a spokeswoman told Reuters that “as part of our standard practice following any accident or incident, we examine our aircraft design and operation, and when appropriate, issue bulletins and make recommendations to operators to further enhance safety…Boeing continues to evaluate the need for software or other changes as we learn more from the ongoing investigation.”
The 737 MAX is a key product for Boeing, which has 4,542 of the upgraded 737 MAX on order from airlines worth over US500 billion at list prices. Boeing has delivered 241 of the jets to customers since it entered service last year, according to its website.
Indonesia’s Lion Air, which has a spotty safety record, is said to be reviewing its own orders for more 737 MAX jets. Lion Air co-founder Rusdi Kirana is said to be furious over what he regards as attempts by Boeing to deflect attention from the MCAS design changes and blame Lion Air for the crash, while the airline faces scrutiny over its maintenance record and pilots’ actions. No final decision has been made, but discussion over the fate of US$22 billion of remaining orders highlights the stakes surrounding an investigation involving Boeing’s fastest-ever selling jet, the 737 MAX, which entered service last year. Lion Air has 190 Boeing jets worth US$22 billion at list prices waiting to be delivered, on top of 197 already taken, making it one of the largest US export customers.
Indonesia’s National Transportation Safety Committee (KNKT), which is investigating the crash, issued a preliminary report on the investigation, revealing that the aircraft had malfunctioned during the flight from Denpasar to Jakarta the night before the incident. The flight data recorder showed that the plane’s stick shaker, a device that warns the pilot of an imminent stall, was active prior to and during the flight from Denpasar.