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Comment by __m | Hacker News Reader

Wouldn’t they eventually all freeze at roughly the same position when the AoA doesn’t change for a while? Can’t they be heated?

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They definitely are now. If you want to see what they look like, the channel AvE on YouTube tears one down (Search for BOLTR AoA) and discusses the mechanics. You can see what they suspect to be small cables for heating go up into the element.

https://www.youtube.com/watch?v=NhZ0D-JRtz0

The A350 has two types of AoA sensor - vanes and multifunction probes - which should reduce the chance of everything failing together.

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".

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...

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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