Seattle - Boeing was aware of problems with the anti-stall software of the 737 MAX jets a year before the first crash of the type, report says.
On May 5, Boeing admitted that a few months after the delivery of the first 737 MAXs in 2017, the manufacturer discovered that a safety warning system in the cockpit was not working properly.
The AOA Disagree Alert only appeared to work in combination with another optional function, the AOA indicator. From its own research, Boeing concluded that the non-working safety option wasn't causing a risk for flight safety.
The information was revealed while the US aircraft manufacturer has been criticized for making some safety features in the cockpit paid options for its customers. An alert designed to show discrepancies in Angle of Attack readings from two sensors was optional on the 737 MAXs.
The report also says that Boeing did not inform the Federal Aviation Administration until a week after the Lion Air 737 MAX 8 crash last year in October. The FAA subsequently issued an Airworthiness Directive.
“Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane,” Boeing said.
“They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes,” the plane maker added.
Boeing said a Safety Review Board convened after the Lion Air Flight 610 crash confirmed its prior conclusion that the alert was not necessary for the safe operation of the aircraft.
The FAA backed this assessment, but criticized Boeing for being late to disclose the issue.
It is not clear whether the non-functioning AOA Disagree specifically played a role in the crashes. The software update that Boeing is currently working on, ensures that the AOA Disagree Alert becomes a standard option on the 737 MAX. The AOA (Angle of Attack) indicator will continue to remain optional.