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UK air traffic control meltdown

jameshaydon.github.io

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Re: UK air traffic control meltdown

#311

Post by gorkish »

retrocryptid wrote: post #297
DyslexicAtheist wrote: post #278

Earlier quoted context omitted.

> Pilots occasionally have to fat finger them into ruggedized I/O devices you're saying what-3-words (W3W) is unsuitable for safety critical applications ? /s

Something like what3words might be useful, but what3words itself doesn't have enough "auditory distance" between words. (i.e. - there are some/many words used by what3words that sound similar enough to be indistinguishable over an audio channel with noise.) Something like FixPhrase seems better for use over radio.

I mean there is the ICAO phonetic alphabet already known and used by every single licensed pilot the world over, regardless of their native language.

or, or... hang with me here for a minute...

We could instead use one of these cool new hash algorithms that require a computer and use about fifteen thousand English words! I understand they are all the rage in the third world countries that lack a postal system.

Re: UK air traffic control meltdown

#312

Post by epolanski »

crabbone wrote: post #232
theptip wrote: post #169

Earlier quoted context omitted.

None of this really argues against fuzz testing; even with completely bogus/malformed flight plans, it shouldn't be possible for a dead letter to take down the entire system. And, since it's translating between an upstream and downstream format (and all the validation is done when ingesting the upstream), you probably want to be sure anything that is valid upstream is also valid downstream. It's true that fuzz testin…

This is not against the principle of fuzz testing. This is to say that the author doesn't really know the reality of testing and is very quick to point fingers. It's easy to tell in retrospect that this particular aspect should've been tested. It's basically impossible to find such defects proactively.

I've read both messages and I'm still unsure on how fuzzy testing may have not brought up similar edge cases.

We literally talking about a parser shutting down an entire system rather than reporting malformed data.

Considering this is a "one in 15M cases" it seems to me that fuzzy testing would've caught this and probably more bugs in a short time span.

Re: UK air traffic control meltdown

#313

Post by lxgr »

joshuamorton wrote: post #294
DyslexicAtheist wrote: post #278

Earlier quoted context omitted.

> Pilots occasionally have to fat finger them into ruggedized I/O devices you're saying what-3-words (W3W) is unsuitable for safety critical applications ? /s

I'm trying to imagine someone ensuring differentiation between minimums.unsettled.depends (Idaho), minimums.unsettled.depend (Alaska), minimums.unsettles.depend (Spain), and minimum.unsettles.depend (Russia) while typing them in on a t-9 style keypad with a 7 figure display in turbulence.

That's easily fixed – just spell them out using the ICAO spelling alphabet!

Re: UK air traffic control meltdown

#314

Post by NikolaNovak »

gorkish wrote: post #311
retrocryptid wrote: post #297

Earlier quoted context omitted.

Something like what3words might be useful, but what3words itself doesn't have enough "auditory distance" between words. (i.e. - there are some/many words used by what3words that sound similar enough to be indistinguishable over an audio channel with noise.) Something like FixPhrase seems better for use over radio.

I mean there is the ICAO phonetic alphabet already known and used by every single licensed pilot the world over, regardless of their native language. or, or... hang with me here for a minute... We could instead use one of these cool new hash algorithms that require a computer and use about fifteen thousand English words! I understand they are all the rage in the third world countries that lack a postal system.

These are all lovely technical solutions. The problem I imagine isn't coming up with unique words. The problem is organizing a switchover for dozens if not hundreds of systems and agencies around the world. The chaos of change is probably out weighing the benefits.

Re: UK air traffic control meltdown

#315

Post by elzbardico »

rglover wrote: post #31

This is one of the many reasons there should be a universal data standard using a format like JSON. Heavily structured, easy to parse, easy to debug. What you lose in footprint (i.e., more disk space), you gain in system stability. Imagine a world where everybody uses JSON and if they offer an API, you can just consume the data without a bunch of hoop jumping. Failures like this would vanish overnight.

The problem was not in the format, but with the way the semantics of the data is understood by the system. It could be fixed-width, XML, json, whatever, and the problem would still be the same.

Re: UK air traffic control meltdown

#316

Post by lxgr »

bsder wrote: post #268
epanchin wrote: post #215

Earlier quoted context omitted.

What three words would be a better solution than a guid, as transmittable over radio.

WTW is a proprietary system that should never be used: https://www.walklakes.co.uk/opus64534.html The biggest fault (besides being proprietary) is that you must be online in order to use WTW. The times that you might need WTW are ALSO the times you are most likely to be unable to be online.

> The biggest fault (besides being proprietary) is that you must be online in order to use WTW.

That doesn't seem to be the case anymore.

It's still not a great system – many included words are ambiguous (e.g. English singular and plural forms are both possible, and an "s" is notoriously difficult to hear over a bad phone line), and it's proprietary, as you already mentioned.

Re: UK air traffic control meltdown

#317

Post by jonny_eh »

joshuamorton wrote: post #294
DyslexicAtheist wrote: post #278

Earlier quoted context omitted.

> Pilots occasionally have to fat finger them into ruggedized I/O devices you're saying what-3-words (W3W) is unsuitable for safety critical applications ? /s

I'm trying to imagine someone ensuring differentiation between minimums.unsettled.depends (Idaho), minimums.unsettled.depend (Alaska), minimums.unsettles.depend (Spain), and minimum.unsettles.depend (Russia) while typing them in on a t-9 style keypad with a 7 figure display in turbulence.

That seems like a huge flaw in their system, has it never been addressed?

Re: UK air traffic control meltdown

#318

Post by lxgr »

t0mas88 wrote: post #298
lxgr wrote: post #189

Earlier quoted context omitted.

Flight plans do inform ATC where and when a plane is expected to enter their FIR though, no?

Only theoretically. In practice the only thing that usually matches is from which other ATC unit the plane is coming. But it could be on a different route and will almost always be at a different time due to operational variation. That doesn't matter, because the previous unit actively hands the plane over. You don't need the flight plan for that. What does matter is knowing what the plane is planning to do inside yo…

> the previous unit actively hands the plane over. You don't need the flight plan for that.

I thought practically, what's handed over is the CPL (current flight plan), which is essentially the flight plan as filed (FPL) plus any agreed-upon modifications to it?

> Because if you don't give any other instructions, the plane will follow the filed routing. Making turns on its own, because the departing ATC unit cleared it for that route.

Without voice or datalink clearance (i.e. the plane calling the new ATC), would the flight even be allowed to enter a new FIR?

Re: UK air traffic control meltdown

#319

Post by darkclouds »

amiga386 wrote: post #134
darkclouds wrote: post #7

Interesting to see that flight plans over the UK have to be filed 4 hours in advance. No mention of plane, pilot, passenger and cargo manifests. So why the 4 hour lead time, is this the time it takes UK Authorities to look people up or workout if the cargo could be dangerous in an airborne Anthrax (Gruinard) Island [1] or Japanese subway Sarin [2], or an IRA favourite, fertilizer bomb thats bypassed the usual purchas…

> so why the 4 hour lead time To answer your question without conspiracy drivel, let's look up CAP 694: The UK Flight Planning Guide [0] Chapter 1 > 6.1 The general ICAO requirement is that FPLs should be filed on the ground at least 60 minutes before clearance to start-up or taxi is requested. The "Estimated Off Block Time" (EOBT) is used as the planned departure time in flight planning, not the planned airborne tim…

So on point 3 then, why do countries, turn people away at the destination and not before take off, if their visa or passport is not in order?

Are their systems not joined up, or does the state just like making examples of peoples once on the destination country? I can watch this stuff happening to people at airport border controls on TV all the time so which is it? Their systems are not joined up or they just like making examples of people?

Re: UK air traffic control meltdown

#320

Post by jameshart »

hn_throwaway_99 wrote: post #168
adrianmonk wrote: post #131

Earlier quoted context omitted.

Because the code classified it as a "this should never happen!" error, and then it happened. The code didn't classify it as a "flight plan has bad data" error or a "flight plan data is OK but we don't support it yet" error. If a "this should never happen!" error occurs, then you don't know what's wrong with the system or how bad or far-reaching the effects are. Maybe it's like what happened here and you could have co…

I agree with the general sentiment "if you see an unexpected error, STOP", but I don't really think that applies here. That is, when processing a sequential queue which is what this job does, it seems to me reading the article that each job in the queue is essentially totally independent. In that case, the code most definitely should isolate "unexpected error in job" from a larger "something unknown happened processi…

If the code takes a valid series of ICAO waypoints and routes, generates the corresponding ADEXP waypoint list, but then when it uses that to identify the ICAO segment that leaves UK airspace it's capable of producing a segment from before when the route enters UK airspace, then that code is wrong, and who knows what other failure modes it has?

Maybe it can also produce the wrong segment within British airspace, meaning another flight plan might be processed successfully, but with the system believing it terminates somewhere it doesn't?

Maybe it's already been processing all the preceding flight plans wrongly, and this is just the first time when this error has occurred in a way that causes the algorithm to error?

Maybe someone's introduced an error in the code or the underlying waypoint mapping database and every flight plan that is coming into the system is being misinterpreted?

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