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Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

flightglobal.com

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Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#291

Post by p_l »

mnw21cam wrote: post #238
tialaramex wrote: post #113

Earlier quoted context omitted.

Indeed. There are plenty of things in aviation where they care so much about compatibility that something survives decades after it should reasonably be obsolete and replaced. Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Got a safety-of-life emergency on an ocean liner, oil tanker or whatever? Everywhere in the entire world mandates…

Air pressure is reported in hectopascals and fuel quantity in kilograms (or tons). It's only in America where this isn't the case. We're still using feet for altitude in most places though (it's mainly Russia that uses metres).

Feet are "optionally accepted" due to USA being China of aviation and flooding the market with feet-marked hardware

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#292

Post by mannykannot »

cryptonector wrote: post #278
mannykannot wrote: post #137

Earlier quoted context omitted.

It does not seem reasonable when you put it like that, but when could it be said with confidence that it only affected just one flight plan? I get the impression that it is only in hindsight that this could be seen to be so. On the face of it, this was just an ordinary transatlantic flight like thousands of others, with no reason to think there was anything unusual about it to make it more vulnerable than the rest -…

Shutting down a flight control system might have other knock-on effects on flight safety. Even if it merely only grounded flights not yet in the air, the resulting confusion might lead to manual mistakes and/or subsequent air lane congestion that might cause collisions.

every option had risks associated with it, and they are hard to assess until you know how deep the problem goes.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#293

Post by Arainach »

mithametacs wrote: post #213
lmm wrote: post #195

Earlier quoted context omitted.

> If it's a good bug accurately describing a real thing, there's no reason to throw that work away rather than just marking it lower priority. Perhaps. But the triage to separate the "good bugs accurately describing real things" from the chaff isn't free either.

Storage is cheap, database indexes work. Just add a `TimesChecked` counter to your bug tracker. Now when considering priorities, consider not just impact and age, but also times checked. It's less expensive than going and deleting stuff. Unless you're automating deletions? In which case... I don't think I can continue this discussion.

We already have a TimesChecked counter:

If (status != Active) { /* timesChecked > 0 */ }

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#294

Post by eru »

jjk166 wrote: post #286
eru wrote: post #187

Earlier quoted context omitted.

> 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.

Thanks, yes, I meant torque.

Well, 1 J = 1 Nm, the differentiation you mention only helps humans a bit, but would be really hard to make work for a computer.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#295

Post by lmm »

d1sxeyes wrote: post #250
lmm wrote: post #220

Earlier quoted context omitted.

> The only point I’m really making is that the data OP referred to does not show an increase in excess deaths, and in fact specifically fails to find this. That data absolutely does show an increase in deaths, it's right there in the table. It fails to find a statistically significant increase in deaths. The most plausible explanation for that is that the study is underpowered because of the sample size, not that som…

> That data absolutely does show an increase in deaths Please be careful about removing the word 'excess' here. The word 'excess' is important, as it implies statistical significance (and is commonly understood to mean that - https://en.wikipedia.org/wiki/Excess_mortality ). I didn't argue that there was no change in the number of deaths, and I did not say that the table does not show any change in the number of deat…

So what is your actual model here? Do you believe that the rate of injuries didn't actually go up (despite the statistically significant evidence that it did), that some mysterious mechanism increased the rate of injuries without increasing the rate of deaths, or that the rate of deaths really did increase, but not by enough to show in the stats (which are much less sensitive to deaths than to injuries, just because deaths are so much rarer)? I know which of those three possibilities I think is more plausible.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#296

Post by wolrah »

astrange wrote: post #160
exe34 wrote: post #138

Earlier quoted context omitted.

it's more fun/creative/CV-worthy to write new shiny features than to fix old problems.

I think a more subtle issue is that fixing old bugs can cause new bugs. It's easier to fix something new, for instance because you understand it better. At some point it can be safest to just not touch something old. Also, old bugs can get fixed by accident / the environment changing / the whole subsystem getting replaced, and if most of your long tail of bugs is already fixed then it wastes people's time triaging it…

> I think a more subtle issue is that fixing old bugs can cause new bugs.

Maybe it's years of reading The Old New Thing and similar, maybe it's a career spent supporting "enterprise" software, but my personal experience is that fixing old bugs causing new bugs happens occasionally, but far more often it's that fixing old bugs often reveals many more old bugs that always existed but were never previously triggered because the software was "bug compatible" with the host OS, assumptions were made that because old versions never went outside of a certain range no newer versions ever would, and/or software just straight up tinkered with internal structures it never should have been touching which were legitimately changed.

Over my career I have chased down dozens of compatibility issues between software packages my clients used and new versions of their respective operating systems. Literally 100% of those, in the end, were the software vendor doing something that was not only wrong for the new OS but was well documented as wrong for multiple previous releases. A lot of blatant wrongness was unfortunately tolerated for far too long by far too many operating systems, browsers, and other software platforms.

Windows Vista came out in 2006 and every single thing that triggered a UAC prompt was a thing that normal user-level applications were NEVER supposed to be doing on a NT system and for the most part shouldn't have been doing on a 9x system either. As recently as 2022 I have had a software vendor (I forget the name but it was a trucking load board app) tell me that I needed to disable UAC during installs and upgrades for their software to work properly. In reality, I just needed to mount the appropriate network drive from an admin command prompt so the admin session saw it the same way as the user session. I had been telling the vendor the actual solution for years, but they refused to acknowledge it and fix their installer. That client got bought out so I haven't seen how it works in 2024 but I'd be shocked if anything had changed. I have multiple other clients using a popular dental software package where the vendor (famous for suing security researchers) still insists that everyone needs local admin to run it properly. Obviously I'm not an idiot and they have NEVER had local admin in decades of me supporting this package but the vendor's support still gets annoyed about it half the time we report problems.

As you might guess, I am not particularly favorable on Postel's Law w/r/t anything "big picture". I don't necessarily want XHTML style "a single missing close tag means the entire document is invalid" but I also don't want bad data or bad software to persist without everyone being aware of its badness. There is a middle ground where warnings are issued that make it clear that something is wrong and who's at fault without preventing the rest of the system from working. Call out the broken software aggressively.

tl;dr: If software B depends on a bug or unenforced boundary in software A, and software A fixing that bug or enforcing that boundary causes software B to stop working, that is 100% software B's problem and software A should in no way ever be expected to care about it. Place the blame where it belongs, software B was broken from the beginning we just hadn't been able to notice it yet.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#297

Post by d1sxeyes »

lmm wrote: post #295
d1sxeyes wrote: post #250

Earlier quoted context omitted.

> That data absolutely does show an increase in deaths Please be careful about removing the word 'excess' here. The word 'excess' is important, as it implies statistical significance (and is commonly understood to mean that - https://en.wikipedia.org/wiki/Excess_mortality ). I didn't argue that there was no change in the number of deaths, and I did not say that the table does not show any change in the number of deat…

So what is your actual model here? Do you believe that the rate of injuries didn't actually go up (despite the statistically significant evidence that it did), that some mysterious mechanism increased the rate of injuries without increasing the rate of deaths, or that the rate of deaths really did increase, but not by enough to show in the stats (which are much less sensitive to deaths than to injuries, just because…

We are talking about excess deaths, not injuries. It feels like the direction you are taking is going further and further away from the original point, and you are misrepresenting what I have said to fit your argument.

I did not say that injuries did not go up. I did not say that the rate of deaths did not go up. I did not say that the rate of deaths did not “show in the stats” (unless by that you mean “was not statistically significant”).

I don’t need a model for the injuries question because that isn’t the point we’re arguing, but I might suggest something like “after 9/11, people took out more comprehensive health insurance policies, and so made claims for smaller injuries than they would have in previous years”.

A suitable model for explaining excess deaths might be something like “after 9/11, people chose to drive instead of fly, and driving is more dangerous per mile than flying is, resulting in excess deaths”. I’m not sure if that is your exact model, but it’s typically what people mean, happy for you to correct.

The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven.

Out of interest, what would be your model for explaining why there were more injuries per mile?

If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong?

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#298

Post by lmm »

d1sxeyes wrote: post #297
lmm wrote: post #295

Earlier quoted context omitted.

So what is your actual model here? Do you believe that the rate of injuries didn't actually go up (despite the statistically significant evidence that it did), that some mysterious mechanism increased the rate of injuries without increasing the rate of deaths, or that the rate of deaths really did increase, but not by enough to show in the stats (which are much less sensitive to deaths than to injuries, just because…

We are talking about excess deaths, not injuries. It feels like the direction you are taking is going further and further away from the original point, and you are misrepresenting what I have said to fit your argument. I did not say that injuries did not go up. I did not say that the rate of deaths did not go up. I did not say that the rate of deaths did not “show in the stats” (unless by that you mean “was not stati…

> The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven.

> Out of interest, what would be your model for explaining why there were more injuries per mile?

Well, is there a statistically significant difference in the injuries per mile? Or even a difference at all? That the difference in injuries was statistically different and the difference in miles driven wasn't does not imply that the former changed by a larger proportion than the latter.

Pretty much everyone including all of the papers we've talked about assumes there was an increase in driving. Do you actually think driving didn't increase? Or is this just another area where these concepts of "statistically significant" and "excess" are obscuring things rather than enlightening us?

> If you found a single story of someone deciding to drive instead of take a plane in October 2001 because of 9/11, and that person died in a car crash, would that be enough for you to be satisfied that I am wrong?

I'm interested in knowing whether deaths actually increased and by how much; for me statistical significance or not is a means to an end, the goal is understanding the world. If we believe that driving did increase, then I don't think it's a reasonable null hypothesis to say that deaths did not increase, given what we know about the dangers of driving. Yes, it's conceivable that somehow driving safety increased by exactly the right amount to offset the increase in driving - but if that was my theory, I would want to actually have that theory! I can't fathom being satisfied with the idea that injuries somehow increased without increasing deaths and incurious not only about the mechanism, but about whether there really was a difference or not.

All of these things - miles driven, injuries, deaths - should be closely correlated. If there's evidence that that correlation actually comes apart here, I'm interested. If the correlations hold up, but the vagaries of the statistics are such that the changes in one or two of them were statistically significant and the other wasn't, meh - that happens all the time and doesn't really mean anything.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#299

Post by d1sxeyes »

lmm wrote: post #298
d1sxeyes wrote: post #297

Earlier quoted context omitted.

We are talking about excess deaths, not injuries. It feels like the direction you are taking is going further and further away from the original point, and you are misrepresenting what I have said to fit your argument. I did not say that injuries did not go up. I did not say that the rate of deaths did not go up. I did not say that the rate of deaths did not “show in the stats” (unless by that you mean “was not stati…

> The problem with that model is that there’s no statistically significant increase in miles driven either. I can’t think of a model which would explain a higher fatality/injury rate per mile driven. > Out of interest, what would be your model for explaining why there were more injuries per mile? Well, is there a statistically significant difference in the injuries per mile? Or even a difference at all? That the diff…

The study does not quote miles driven in their specific sample so I can’t talk to this or answer your question directly, and the national numbers don’t cover injuries. The numbers in the survey are also a bit vague about injuries, and include “possible injuries”, “injury with severity unknown”, and they are taken separately from incapacitating injury data. The data on injuries is objectively lower quality than the data on deaths, and anyway deaths was the focus of the original question, so I’d rather avoid getting sidetracked.

To respond to your question (admittedly not to answer directly), nationally there was indeed an increase in miles driven, an additional 59 billion miles in 2002 compared to 2001, and indeed there was an increase in deaths. I would also expect an increase in injuries as well.

Looking at this in isolation, you can say “oh so because of 9/11, people drove 59 billion more miles which resulted in more deaths and injuries”, but in my opinion real question if you want to understand the world better is “how many more miles would folks have driven in 2002 compared to 2001 in case 9/11 never happened”.

We obviously can’t know that, but we can look at data from other years. For example, from 1999 to 2000, the increase in miles driven was 56 billion, from 2000 to 2001, the increase was 50 billion and from 2002 to 2003 the increase was 34 billion, from 2003-2004 the increase was 75 billion.

Miles driven, injuries, deaths, are indeed all closely correlated. But so is population size, the price of oil, and hundreds of other factors. If your question is “did more people die on the roads in 2002 than in 2001”, the answer is yes. Again, I assume that the same is also true of injuries although I can’t support that with data.

That wasn’t OP’s assertion though, OP’s assertion was that closing down airspace does not lead to zero excess deaths. My argument is that the statistics do not support that conclusion, and that the additional deaths in 2002 cannot rigorously be shown even to be unusually high, let alone caused by 9/11.

Re: Air traffic failure caused by two locations 3600nm apart sharing 3-letter code

#300

Post by sandos »

d1sxeyes wrote: post #127
mjevans wrote: post #80

Earlier quoted context omitted.

Reject the flight plan would be the last case scenario, but where it should have gone without other options rather than total shutdown. CORRECT the flight plan, by first promoting the exit/entry points for each autonomous region along the route, validating the entry/exit list only, and then the arcs within, would be the least errant method.

You can’t just reject or correct the flight plan, you’re a consumer of the data. The flight plan was valid, it was the interpretation applied by the UK system which was incorrect and led to the failure. There are a bunch of ways FPRSA-R can already interpret data like this correctly, but there were a combination of 6 specific criteria that hadn’t been foreseen (e.g. the duplicate waypoints, the waypoints both being o…

If this is the case, then every system along the flightplan should pre-validate it before it gets accepted at the source?
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