Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

Re:Boeing altered key switches in 737 MAX cockpit limiting a... by rurban on Sunday May 12, 2019 @03:05AM (#19890593)

They are heated now, after the Air France loss. This incident was also the reason for the MCAS system in the first hand: "Don't trust the pilot, regulate it into safety by your own".

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Re:Boeing altered key switches in 737 MAX cockpit limiting a... by presto8 on Sunday May 12, 2019 @11:15AM (#19892395)

Are you referring to AF447? According to the BEA incident report, the AF447 plane was already equipped with heating systems for the pitot probes and AoA sensors.

"1.6.9.1 Probe heating The probes that are installed on the aircraft are heated electrically to remove water by vaporisation when the aeroplane is on the ground and to protect them from icing in flight."

Reference: https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp09060...

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Re:Boeing altered key switches in 737 MAX cockpit limiting a... by rurban on Sunday May 12, 2019 @03:13PM (#19893818)

Right, I mixed that up. With AF447 the initial problem was not the AOA but the very common pitot tube icing, which renders the airspeed indicator useless, thus leading to wrong stall warnings.

Even if the pitot tube is heated (mandatory), very often airframe icing leads to a blocked static port, rendering even more indicators useless.

https://en.wikipedia.org/wiki/Pitot-static_system

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