Boeing left out a 737 Max safety feature linked to its fatal crashes, despite including it on an earlier plane, report claims
- 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.Advertisement
In this plane, the system worked with multiple sensors - giving the pilots more control over the plane, according to the report.
David Ryder/Getty Images
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.Preliminary reports from investigations into the two crashes suggested that there were problems with the sensor readings.Advertisement
In both flights, the planes nosedived and pilots were unable to regain control.
Eddy Purwanto/NurPhoto via Getty Images
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 planesAdvertisement
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.
Ted S. Warren/Associated Press
Boeing has since defended its design. In response to the CNN report, a spokesperson said that "single sources of data are considered acceptable in such cases by our industry."The plane will not fly again until regulators in the US and around the world approve Boeing's fixes - a process that most in the industry do not expect to be completed until the end of 2019 at the earliest.Advertisement
Sources for The Wall Street Journal said this fix will make the MCAS system in the Max plane more similar to the one in the military jet.Advertisement
An Air Force official and other unnamed sources told the Journal that the military refuelling jet with the MCAS system also has another safeguard, which lets pilots override the system by pulling on the controls.Will Roper, an assistant Air Force secretary who serves as the branch's procurement chief, said: "We have better sensor data."Advertisement
Max pilots have criticized Boeing for what they described as a plane design that lessens their control over the plane, in ways they say they were told of in advance.Read more: The Boeing 737 Max could be grounded through the holidays thanks to a series of new delays, and airlines are cancelling thousands of flights because of itAdvertisement
American Airlines pilots confronted Boeing executives about the MCAS system in November 2018, after the first crash but before the second.Boeing is currently facing lawsuits from the families of those killed on the planes, as well as federal investigations and demands for compensation from airlines around the world who have had their planes grounded and unable to fly since March.Advertisement
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