Boeing said Sunday some of its 737 Max jetliners were accidentally delivered with one of the cockpits’ warning lights as an optional addition, rather than a standard feature of the new aircraft, and that the company knew for months before informing the Federal Aviation Administration.
The aerospace giant said in a statement a warning light related to two sensors meant to determine a plane’s position in the sky was turned off in most 737 Max planes. Boeing meant to have the feature installed as a standard component of every 737 Max cockpit, but instead the light was linked to a premium upgrade that only some airlines chose to pay for. The FAA was only told about the mistake near the end of last year, 13 months after Boeing first discovered the flaw.
The company defended itself on Sunday, saying the warning light was not an essential safety feature and that its own investigators determined it in no way impacted the safety of the planes. Other common safety features were unaffected, Boeing said.
“Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane,” Boeing said in the statement. “They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes.”
Sunday’s statement is the first public admission by Boeing that a component of the 737 Max was faulty in some way. Only 20% of the planes ordered by airlines worldwide included the upgrade that would have activated the warning sensor. Neither Lion Air and Ethiopian Airlines planes had purchased the upgrade, per The New York Times.
Boeing said once it determined in 2017 that the warning light software wasn’t standard, a team of company-employed experts found it “did not adversely impact airplane safety or operation. The team concluded that the warning light could safely remain inactive on affected planes until the next software update, and the company did not inform the FAA at the time.
Around a week after the Lion Air accident, Boeing said it issued a bulletin related to the sensor and informed the FAA. The aerospace company also had a second team related to Boeing’s Safety Review Board investigated the importance of the alert, and the experts also found that the additional warning light would not impact aircraft safety.
Boeing said Sunday it was working to implement the warning light feature as standard before the 737 Max returns to service.
Many airline employee unions reacted Sunday with more questions about Boeing’s candor during the investigation process.
“The question I have is just like we asked them in Reno, ‘Is that all there is?’” Jon Weaks, the head of the Southwest Airlines Pilots Association, told Bloomberg News.
A spokesman for the FAA told The Associated Press the agency determined planes lacking the warning indicator presented a low risk, but said that hearing from Boeing earlier in the process would have “helped to reduce or eliminate possible confusion.”
The angle of attack sensors have come under scrutiny following two separate crashes involving the 737 Max. Last October, a Lion Air plane crashed shortly after taking off from the Jakarta airport, killing everyone on board. And in March, an Ethiopian Airlines flight crashed after leaving the country’s capital. Everyone on that plane also died.
Boeing software called the Maneuvering Characteristics Augmentation System (MCAS), meant to keep the 737 Max planes from stalling in mid-air, has also been under review. The Seattle Times said last month it found crucial flaws in the safety analysis of MCAS.
Boeing has said the MCAS system was activated in both of the crashes, pushing the noses of the planes downward, but has not directly linked the software to the accidents.