Boeing knew of a software error that prevented the correct functioning of a safety alert system on the 737 Max for a year before disclosing the problem to regulators and airlines. And Legalbrief reports that Monday's horrific crash-landing of an Aeroflot aircraft in Russia has highlighted the dangers of humans and electronic systems fighting for control. It appears that Boeing waited until after the October Lion Air crash to begin notifying airlines that the alert system had an issue and waited five months, until the Ethiopian Airlines crash, to reveal more details. The Wall Street Journal reported that another six weeks passed before the public and FAA acting chief Daniel Elwell learned of the issue. The software error was specifically related to the ‘angle-of-attack disagree alert,’ which is supposed to tell pilots whether or not the nose-angle sensor is working properly. A report on the Business Insider site notes that Boeing will now make the alert system standard as was initially intended. The company claims that previously it had accidentally made the system an optional add on.

A fatal airplane crash a decade ago prompted a life-saving fix across thousands of Boeing 737 cockpits. Investigators of the 2009 crash of a Turkish Airlines jet identified a faulty altitude sensor that thought the plane was closer to the ground than it was and triggered the engines to idle. The plane’s second radio altimeter displayed the correct elevation, but it didn’t matter: the automatic throttle was tied to the first gauge. Moneyweb reports that the Amsterdam-bound plane crashed into a field, killing nine people and injuring 120. Boeing ended up changing that throttle system to prevent one erroneous altitude reading from cascading into tragedy. However, when the Max debuted two years ago with a new flight-control feature to help pilots avoid a stall, it was designed to react to only one of the plane’s two ‘angle of attack’ sensors that measure the jet’s incline. That proved deadly when malfunctioning sensors on jets operated by Lion Air and Ethiopian Airlines automatically commanded the noses of the planes down over and over, even though the other sensor showed it wasn’t necessary. ‘When I read that the planes had two angle-of-attack sensors, I couldn’t think of a reason why they wouldn’t use both,’ said Robert Canfield, an aeronautical engineering professor and technical director of the Virginia Tech Airworthiness Centre. A software fix for the 737 Max that is now in testing will do just that.