I’m curious what part of the code rejected the validity of the flight plan. Im also curious what keys are actually used for lookups when they aren’t unique??
Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
281–290 of 311 posts
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#282Earlier quoted context omitted.
We better get this sorted out before open source manned Mars missions. That all programming languages, down to statically typed assembly, don’t support something as simple to validate as unit consistency says something strange about how the science of replacing unreliable manual processes with automated systems is really bad at the practice of replacing its own risky manual processes with automated systems. If numeri…
Some languages do; F# and Ada have units. I agree no sexy languages have it, and almost all languages have terrible support or anti-support for correctness in numerical programming. It's very strange. (By anti-support I mean things that waste your time and make it harder. For instance, a lot of languages think "static typing" means they need to prevent you from doing `int a,b; short c = a * b;` even if this is totall…
Whenever it's vague, I include the units as part of the parameter name (eg. delay_ms). Not perfect, but for practical purposes it helps. It's simple and I'm not sure why there aren't more people/libraries doing this.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#283Earlier quoted context omitted.
That's not what an exception proving a rule means. It has a technical meaning: a sign that says "free parking on sundays" implies parking is not free as a rule. When used like this it just confuses a reader with rethoric. In this case netflix is just bad at live streaming, they clearly haven't done the necessary engineering work on it.
The fact that Netflix surprised so many people by an exceptional technical issue implies that as a rule Netflix delivers video smoothly and at any scale necessary.
Yes! THIS is precisely what I meant in my comment.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#284Earlier quoted context omitted.
True, but it's the exception that proves the rule; it's also the same company responsible for delivering a staggeringly high percentage of internet video, typically without a hitch.
That's not what an exception proving a rule means. It has a technical meaning: a sign that says "free parking on sundays" implies parking is not free as a rule. When used like this it just confuses a reader with rethoric. In this case netflix is just bad at live streaming, they clearly haven't done the necessary engineering work on it.
That's also not what "an exception proving the rule" is either. The term comes from a now mostly obsolete* meaning of prove meaning "to test or trial" something. So the idiom properly means "the exception puts the rule to the test." If there is an exception, it means the rule was broken. The idiom has taken on the opposite meaning due to its frequent misuse, which may have started out tongue in cheek but now is used unironically. It's much like using literally to describe something which is figurative.
* This is also where we get terms like bulletproof - in the early days of firearms people wanted armor that would stop bullets from the relatively weak weapons, so armor smiths would shoot their work to prove them against bullets, and those that passed the test were bullet proof. Likewise alcohol proof rating comes from a test used to prove alcohol in the 1500s.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#285[deleted]
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#286Earlier quoted context omitted.
We better get this sorted out before open source manned Mars missions. That all programming languages, down to statically typed assembly, don’t support something as simple to validate as unit consistency says something strange about how the science of replacing unreliable manual processes with automated systems is really bad at the practice of replacing its own risky manual processes with automated systems. If numeri…
> That all programming languages, down to statically typed assembly, don’t support something as simple to validate as unit consistency [...] Many programming languages are flexible and strong enough support this. We just don't do it by default, and you'd need libraries. Btw, units by themselves are useful, but not enough. Eg angular momentum and energy have the same units of Newton * metre, but adding them up is not…
> Eg angular momentum and energy have the same units of Newton * metre, but adding them up is not recommended.
The unit of angular momentum is kg.m^2.s^-1, you're thinking of torque. Although even then we distinguish the Newton meter (Nm) from the Joule (J) even if they have the same dimensionality.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#287[dead]
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#288Earlier quoted context omitted.
And this is why you always use surrogate keys and not natural keys. No matter how much you convince yourself that your natural key is unique and will never change, if a human created the value then a human can change the value or create duplicates, and eventually will.
But that wouldn't help you here. The flight plan will come in with the code and you'll still have to resolve that to your keys.
Sure, but that means you are putting in the infrastructure to resolve it, instead of assuming there will never be a need to.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#289This is old news, but what's new news is that last week, the UK Civil Aviation Authority openly published its Independent Review of NATS (En Route) Plc's Flight Planning System Failure on 28 August 2023 https://www.caa.co.uk/publication/download/23337 (PDF) Let's look at point 2.28: "Several factors made the identification and rectification of the failure more protracted than it might otherwise have been. These inclu…
> The Level 2 engineer was rostered on-call and therefore was not available on site at the time of the failure. Having exhausted remote intervention options, it took 1.5 hours for the individual to arrive on-site to perform the necessary full system re-start which was not possible remotely. Which shows that sometimes, remote isn't a viable option. If you have very critical infrastructure, it's advisable to have peopl…
Or you configure your infrastructure to be remotely operated.
Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code
#290Earlier quoted context omitted.
> obscuring this flight's waypoint problem have resulted in a potentially conflicting flight not being tracked among other flights? Flights are tracked by radar and by transponder. The appropriate thing to do is just flag the flight with a discontinuity error but otherwise operate normally. This happens with other statuses like "radio failure" or "emergency aircraft." It's not something you'd see on a commercial flig…
The appropriate thing to do was to reject the flight plan (remember, the flight plan is processed before the flight starts, and anyways there were hours over U.S. in which the flight could have been diverted if manual resolution was not possible), not to let the flight continue with the apparent discontinuity, nor to shutdown the whole system.
> flight plan is processed before the flight starts
Not necessarily. Also they regularly change while the flight is in the air.