A recent statement by Boeing suggests that the company may have withheld important safety information about the Boeing 737 Max for more than a year, involving potential problems with sensors involved in two recent crashes involving the controversial plane.
Boeing issued a press release on Sunday, acknowledging that it learned about discrepancies between two Angle of Attack (AOA) sensors in its 737 MAX passenger jets in 2017. However, it did not inform the U.S. Federal Aviation Administration (FAA) until November 2018, after the crash of a Lion Air flight out of Indonesia.
Angle of attack is the attitude of the wings in relation to airflow. When air flows over the wings at the correct angle, you get lift, which is what makes a plane fly. If the air is not flowing over the wings properly, the plane can stall, which occurs when it loses lift and begins to fall out of the sky.
Boeing’s planes had two sensors, which measured whether the plane had the proper angle of attack to maintain lift. The software was supposed to have an alarm that warned the crew if the two sensors disagreed, known as the AOA Disagree alert.
However, Boeing sold the planes with an optional AOA indicator, which was not standard on every plane. The software used in the planes linked the AOA Disagree alert to the AOA indicator, meaning if the plane did not come with the optional AOA indicator, the AOA Disagree alert would not activate.
This was not supposed to be how the software worked, and Boeing discovered the problem in 2017, within several months of the first planes being shipped out.
However, the company did not notify the FAA until more than a year later in November 2018, about a month after Lion Air Flight 610 crashed into the sea just 13 minutes into its flight, killing all 189 passengers and crew.
Investigators have determined the pilots fought for 11 minutes to keep the plane in the air, likely due to a problem with the plane’s Angle of Attack (AOA) sensor, which kept telling an automated system, which the pilots could not shut off, to point the nose down.
“Boeing discussed the status of the AOA Disagree alert with the FAA in the wake of the Lion Air accident,” the company’s statement indicates. “At that time, Boeing informed the FAA that Boeing engineers had identified the software issue in 2017 and had determined per Boeing’s standard process that the issue did not adversely impact airplane safety or operation.”
A safety review board was convened by Boeing in December 2018, which came to the same conclusion. FAA officials say they agreed that the problem was likely low risk, but said Boeing should have informed the agency far sooner, instead of waiting more than a year. It was 13 months between when Boeing learned of the problem and when it informed the FAA, officials at the agency report.
Months later, another Boeing 737 Max plane fell from the sky just minutes into its flight on March 10, killing all 157 passengers and crew on board Ethiopian Airline Flight 302.
After similarities were discovered between the two crashes, nations worldwide grounded Boeing’s entire 737 MAX fleet until further investigations into this latest crash could be completed and any safety issues addressed. Investigations appear to strongly indicate conflicting AOA sensor data and the automated flight system’s efforts to address the perceived problem, played significant roles in both accidents.
The U.S. Department of Transportation and the Federal Bureau of Investigation have launched a criminal probe into the certification of the Boeing 737 MAX jet, in addition to ongoing investigations by the National Transportation Safety Board as well as French investigators.
The FAA says the 737 MAX will return to service when the agency’s analysis of safety data indicates it is appropriate.
The 737 MAX is Boeing’s best selling aircraft with $500 billion at list prices. The company had 400 planes in operation around the world with orders for 5,000 more before countries began grounding the jets after the recent crashes.
Boeing faces a growing number of wrongful death lawsuits from family members of victims of both accidents.