Boeing left a safety feature off the software on its 737 Max planes that was present in an earlier version of the system, The Wall Street Journal reported.
The anti-stall software system, called MCAS, misfired in the two fatal crashes that killed 346 people, pointing the noses of both planes down into dives from which they never recovered.
The system relied on a single external sensor — a design widely criticised by experts.
But a military jet designed before the Max used MCAS with multiple sensors, sources told the Journal.
Boeing said in response that the two systems “are not directly comparable.”
However, part of the company’s proposed fix for the 737 Max includes data from a second sensor.
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Boeing left a safety feature off the software system on its 737 Max planes that was linked its two fatal crashes, despite including it on an earlier version of that system used elsewhere, a new report claims.
The version of the automated anti-stall system, called MCAS, on the 737 Max relied on data from only one of the plane’s two angle-of-attack sensors, which measure the plane’s angle in the sky.
But Boeing engineers first created the MCAS system more than a decade ago for a military jet used for re-fuelling, The Wall Street Journal reported, citing people familiar with the matter.
In this plane, the system worked with multiple sensors — giving the pilots more control over the plane, according to the report.
Boeing confirmed in April that an erroneous sensor readings triggered the plane’s MCAS software in the two fatal crashes: a Lion Air flight in Indonesia in October 2018 and an Ethiopian Airlines flight in March 2019 in Ethiopia. The crashes killed a total of 346 people.
Read more: The complete history of the 737 Max, Boeing’s promising yet problematic workhorse jet
Preliminary reports from investigations into the two crashes suggested that there were problems with the sensor readings.
In both flights, the planes nosedived and pilots were unable to regain control.
The MCAS system is designed to prevent the aircraft from stalling — which can occur when a plane is angled too sharply up — by automatically pointing the nose down.
Experts have criticised Boeing’s decision to have the plane rely on just one sensor input.
Peter Lemme, a former Boeing flight-controls engineer, told CNN in May that the plane should have had “a fail-safe design” that “relied on two inputs to make sure that you weren’t sensitive to one failure.”
Read more: As the FAA head defended the agency’s handling of the Boeing 737 Max, he suggested that the agency might change its process for certifying new planes
Another flaw is that the sensors are fixed to the outside of the plane, where they can be easily damaged in flight.
US Rep. Peter DeFazio, the chair of the House Transportation and Infrastructure Committee, also said that his committee’s investigation into the 737 Max would look at how its software relied on a single sensor.
Boeing has since defended its …read more
Source:: Business Insider