Who wrote the software? Even though there are two sensors, the signal from the faulty sensor was used. (Why no comparison checks or consensus checks?) Also, t

Who wrote the software? Even though there are two sensors, the signal from the faulty sensor was used. (Why no comparison checks or consensus checks?) Also, there was no limit on how far the MCAS could move the stabilizer. MCAS was limited to 2.5 degrees of change 'per cycle' but each time a pilot tried to pull up the nose, MCAS reset enabling another 2.5 degree of movement. Ultimately the stabilizer was pinned in the max-down position. Boeing and perhaps the FAA let the software into the field but it was bad/lazy software engineers that killed people. Like all 737s, the MAX actually has two of the sensors, one on each side of the fuselage near the cockpit. But the MCAS was designed to take a reading from only one of them. Lemme said Boeing could have designed the system to compare the readings from the two vanes, which would have indicated if one of them was way off. Alternatively, the system could have been designed to check that the angle-of-attack reading was accurate while the plane was taxiing on the ground before takeoff, when the angle of attack should read zero. “They could have designed a two-channel system. Or they could have tested the value of angle of attack on the ground,” said Lemme. “I don’t know why they didn’t.” The black box data provided in the preliminary investigation report shows that readings from the two sensors differed by some 20 degrees not only throughout the flight but also while the airplane taxied on the ground before takeoff. https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/faile...