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Joined 2 years ago
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Cake day: June 14th, 2023

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  • Commercial planes often take off in mild tailwinds; they’re typically certified for 10-15kt of tailwind. It’s sometimes easier for the airport than re-sequencing all the flights especially if it’s only a mild tailwind.

    Florence has hills to one side (the west?) that mean taking off in that direction also carries a performance penalty because you need good engine-out climb rates. So it can be a choice of tailwind or hills.

    It’s all statistics. If you’re never getting surprised by the weather, you are probably leaving money on the table. If it’s happening all the time, you’re selling too many seats.

    It will also depend on how far out the last seat was sold.



  • It’s often not just the heat, but also wind direction both at the airport and enroute. They probably plan for some combination of the three, but not worse case on all at once.

    Headwinds on takeoff mean you can takeoff with more mass. Tailwinds, crosswinds, and higher temperatures mean you can carry less mass.

    Tailwinds enroute mean you get a higher groundspeed for a given airspeed and arrive earlier, having burnt less fuel. If the tailwinds are known before departure, you can carry less fuel (less mass) and thus more payload (passengers).

    There is nothing you can do to ‘prepare’ other than sell fewer tickets (and thus leave the flight unnecessarily empty on days when there isn’t adverse weather) or use a bigger plane that still needs to be lightly loaded.



  • ‘Reduced’ implies manufacturing changes. What if, once the product is reduced, it still can’t be reused/recycled?

    What if the intended life of a product is 50 years maintenance-free after which it’s landfill? Can’t be reused, can’t be refurbed, can’t be recycled - but it’s still generally a good use of resources.

    In many products, there’s a repair-reliability tradeoff. If you pot it, you can’t repair failures, but you’ll reduce the failure rate by >90%. Repair shops hate it because the ones they see can’t be fixed, but they’ don’t see all the ‘easy repairs’ that never needed doing in the first place.











  • Yeah, I’m always a little skeptical about the ‘feel it’ claims. But computers don’t have to adapt to progressive wear; I’m sure you could configure the ABS/traction control to indicate that in dry conditions consistently slipping below say 0.3g (number pulled out of ass) of applied traction implies an excessively worn tire.

    Once you get below a certain level of performance, all the braking/steering assumptions involved in self driving start breaking down too.


  • Airliner engines are getting to ludicrous reliability numbers (the latest generation appears to be closing in on 10M hours between inflight shutdowns) largely through predictive maintenance performed far in advance. We’re well past ‘most pilots never see an engine failure’ and approaching ‘most airlines don’t see an engine failure’.

    And there are few locations more abusive to sensors than the hot section of a turbine engine.


  • And yet people can feel the difference between a worn tire and a new tire. Accelerometers and the torque feedback on the motor drives (both of which are already widespread in cars out of necessity for other equipment) can feel when the tires are on the edge of losing traction.

    One of the changes in automation over the last decade or two is a move away from having many specific ‘sensor for monitoring X’, towards interpreting a smaller number of better sensors in novel ways to provide the same data.