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Having optional safety features on an airplane (i.e. not standard equipment) strikes me as being significantly more egregious (Edit: more so than on vehicles li

Having optional safety features on an airplane (i.e. not standard equipment) strikes me as being significantly more egregious (Edit: more so than on vehicles like cars/trucks for the general population). Considering how complex these things are already, how does this not unnecessarily increase the cognitive load on pilots? "Oh, I guess I'm flying the basic trim level airplane today, I better be cognizant of the fact that it lacks features X, Y and Z"

cjbprime 8y ago
I agree with you. I think in practise the feature choices are made per-airline, perhaps to avoid the pilot confusion you mention. "AOA disagree" specifically seems to have been purchased by only the North American airlines that use the MAX.
- CydeWeys 8y ago
  I'm still trying to wrap my head around the fact that an error warning can be an optional paid extra, even when the error being reported is that sensors are malfunctioning in a way that will cause the plane to override stick input and fly itself into the ground.
  - cjbprime 8y ago
    There is some complicated explanation: the AOA disagree alert requires the presence of the visual AOA indicators, and it's those indicators that are the paid upgrade, and the alert comes along for the ride with them.
    - CydeWeys 8y ago
      Why would AOA indicators be a paid upgrade? Isn't that a pretty fundamental display needed to safely fly the plane? And wouldn't having disparities here between planes create more confusion among pilots?
      - cjbprime 8y ago
        Airlines and general aviation aircraft have totally ignored AoA as a relevant indicator until very recently. You won't find an AoA indicator in even a modern Cessna. As a student pilot you're taught about unsafe low airspeeds instead, even though AoA can technically cause a wing to stall at any airspeed, and even though that memorized stall airspeed ($V_s1$) actually varies with factors like plane weight. AoA is not considered fundamental in commercial aviation, but is considered fundamental in military aviation. Of course, if your commercial aircraft has a tendency towards stall, that changes the calculus on how important AoA is..
        CydeWeys 8y ago
        Thanks for the info. It sounds like commercial aircraft have some catching up to do if this is going to be increasingly important.
        HeyLaughingBoy 8y ago
        AoA is not considered fundamental in commercial aviation, but is considered fundamental in military aviation ISTR that after a carrier catapult takeoff, Naval aviators have 10 seconds for AoA to get into the "green zone." Otherwise it's an automatic eject. Forgot where I read that and if it's only for specific aircraft types, though.
        tyingq 8y ago
        Looks like that changed. AoA is standard equipment on Cessna 172's since 2016: https://www.flightglobal.com/news/articles/aoa-indicator-becomes-standard-for-cessna-172-423942/ https://www.flightglobal.com/news/articles/aoa-indicator-bec...

cjbprime 8y ago

I agree with you. I think in practise the feature choices are made per-airline, perhaps to avoid the pilot confusion you mention. "AOA disagree" specifically seems to have been purchased by only the North American airlines that use the MAX.

CydeWeys 8y ago
I'm still trying to wrap my head around the fact that an error warning can be an optional paid extra, even when the error being reported is that sensors are malfunctioning in a way that will cause the plane to override stick input and fly itself into the ground.
- cjbprime 8y ago
  There is some complicated explanation: the AOA disagree alert requires the presence of the visual AOA indicators, and it's those indicators that are the paid upgrade, and the alert comes along for the ride with them.
  - CydeWeys 8y ago
    Why would AOA indicators be a paid upgrade? Isn't that a pretty fundamental display needed to safely fly the plane? And wouldn't having disparities here between planes create more confusion among pilots?
    - cjbprime 8y ago
      Airlines and general aviation aircraft have totally ignored AoA as a relevant indicator until very recently. You won't find an AoA indicator in even a modern Cessna. As a student pilot you're taught about unsafe low airspeeds instead, even though AoA can technically cause a wing to stall at any airspeed, and even though that memorized stall airspeed ($V_s1$) actually varies with factors like plane weight. AoA is not considered fundamental in commercial aviation, but is considered fundamental in military aviation. Of course, if your commercial aircraft has a tendency towards stall, that changes the calculus on how important AoA is..
      - CydeWeys 8y ago
        Thanks for the info. It sounds like commercial aircraft have some catching up to do if this is going to be increasingly important.
      - HeyLaughingBoy 8y ago
        AoA is not considered fundamental in commercial aviation, but is considered fundamental in military aviation ISTR that after a carrier catapult takeoff, Naval aviators have 10 seconds for AoA to get into the "green zone." Otherwise it's an automatic eject. Forgot where I read that and if it's only for specific aircraft types, though.
      - tyingq 8y ago
        Looks like that changed. AoA is standard equipment on Cessna 172's since 2016: https://www.flightglobal.com/news/articles/aoa-indicator-becomes-standard-for-cessna-172-423942/ https://www.flightglobal.com/news/articles/aoa-indicator-bec...