Boeing knew of 737 MAX safety system glitch year before deadly Indonesian crash

WASHINGTON, Boeing engineers identified a fault with a pilot warning system on its 737 MAX aircraft in 2017, a year before the deadly Lion Air crash in Indonesia, the company said.

Boeing said that management was unaware of the issue until the crash in

Indonesia, which killed 189 people, and the planes were not grounded until

after another of the type operated by Ethiopian Airlines went down several

months later, leaving a further 157 people dead.

According to Boeing, a supposedly standard piece of equipment that tells

pilot about disagreements between angle of attack (AOA) indicators � which measure the plane’s angle vis-a-vis oncoming air to warn of impending stalls � did not in fact activate unless an additional optional indicator was purchased by airlines.

That left airlines that did not buy the optional indicator � including

both Lion Air and Ethiopian Airlines � without the safety feature.

Faulty angle of attack indicator information may have played a role in

both of the deadly crashes, causing the 737 MAX anti-stall system to

unnecessarily activate and push the nose down toward the ground even as

pilots fought to maintain altitude.

In 2017, within several months after beginning 737 MAX deliveries,

engineers at Boeing identified that the 737 MAX display system software did

not correctly meet the AOA Disagree alert requirements, the aircraft

manufacturer said in a statement.

The software delivered to Boeing linked the AOA Disagree alert to the AOA

indicator, which is an optional feature, it said. Accordingly, the software

activated the AOA Disagree alert only if an airline opted for the AOA


A Boeing review determined that the absence of the AOA Disagree alert did

not adversely impact airplane safety or operation, concluding that the

existing functionality was acceptable until the alert and the indicator could

be delinked in the next planned display system software update, Boeing said.

Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.

Boeing’s entire 737 MAX fleet has been grounded since shortly after the

Ethiopian Airlines crash in March, while investigators study the incidents

and engineers work on solutions. � NNN-AGENCIES

Source: NAM News Network