Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

UK air traffic control meltdown

jameshaydon.github.io

Post reply on HN
Print view View original

191–200 of 459 posts

Re: UK air traffic control meltdown

#191

Post by lozenge »

Thorentis wrote: post #184
hn_throwaway_99 wrote: post #168

Earlier quoted context omitted.

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…

Except that you can't be sure this bad flight plan doesn't contain information that will lead to a collision. The system needs to maintain the integrity of all plans it sees. If it can't process one, and there's the risk of a plane entering airspace with a bad flight plan, you need to stop operations.

But they have 4 hours to reach out to the one plane whose flight plan didn't get processed and tell them to land somewhere else.

Re: UK air traffic control meltdown

#192

Post by 1970-01-01 »

lbriner wrote: post #76

I seem to remember another problem at NATS which had the same effect. Primary fell over so they switched over to a secondary that fell over for the exact same reason. It seems like you should only failover if you know the problem is with the primary and not with the software itself. Failing over "just because" just reinforces the idea that they didn't have enough information exposed to really know what to do. The bit…

Yep. In electrical terms, you replaced the fuse to watch it blow again. There are no more fuses in your shop. Progress?

Re: UK air traffic control meltdown

#193

Post by seabass-labrax »

SoftTalker wrote: post #162
seabass-labrax wrote: post #140

Earlier quoted context omitted.

You have to reduce that to the (still massive) set of IDs that are somewhat pronounceable in languages that use the Latin script. You don't want to be the air traffic controller trying to work out how to say 'Lufthansa 451, fly direct QXKCD'. Nonetheless, I think the there is little cause for concern about changing existing IDs. There might be sentimental attachment, but it takes barely a few flights before the new I…

I thought that is what the "ICAO pronunciation" was for? "Fly direct Quebec Xray Kilo Charlie Delta"

It is, but fixes are almost always spoken as words rather than letter-by-letter. For this reason, they are usually chosen to be somewhat pronounceable, and occasionally you even get jokes in the names. Likewise, radio beacons and airports are usually referred to by the name of their location; for instance "proceed direct Dover" rather than "proceed direct Delta Victor Romeo".

I think a lot of pilots and air traffic controllers would be irritated if they had to spend longer reading out clearances and instructions. In a world where vocal communication is still the primary method of air traffic control, there might be a measurable reduction in capacity in some busier regions.

Re: UK air traffic control meltdown

#194

Post by zarzavat »

f1shy wrote: post #174
sam0x17 wrote: post #163

Earlier quoted context omitted.

Why on earth do they not have GUIDs for these navigation points if the names are not globally unique and inter-region routes are commonplace?

The names have to be entered manually by pilots, if e.g. they change the route. They have to be transmitted over the air by humans. So they must be short ans simple.

Yes but shouldn’t one step of the code be to translate these non-unique human-readable identifiers into completely unique machine-readable identifiers?

Re: UK air traffic control meltdown

#195

Post by paulddraper »

sam0x17 wrote: post #163
reactordev wrote: post #28

So they forgot to "geographically disparate" fence their queries. Having built a flight navigation system before, I know this bug. I've seen this bug. I've followed the spec to include a geofence to avoid this bug.

Why on earth do they not have GUIDs for these navigation points if the names are not globally unique and inter-region routes are commonplace?

Aviation protocols are extremely backwards compatible and low-tech compatible.

You need to be able to read, write, hear, and speak the identifier. (And receive/transmit in morse code)

Would it be okay to have an "area code prefix" in the identifier? Plausible (but practically speaking too late for that)

Re: UK air traffic control meltdown

#196

Post by schainks »

rglover wrote: post #95
schainks wrote: post #88

Earlier quoted context omitted.

I have seen a bad outages caused by valid JSON whose consumer implemented something incorrectly. I agree with dundarius that "doing this in JSON" would not have changed the likelihood the bug could have manifested.

No change at all? I find that hard to believe. There's also a data design problem here, but the structure of JSON would aid in, not subtract from, that process. The question at hand is: "heavily structured data vs. a blob of text as input into a complex algorithm, which one is preferred?" Unless you're lying, you'd choose the former given the option.

These old standards ARE heavily structured data, despite what their formatting or lack of punctuation suggests.

Re: UK air traffic control meltdown

#197

Post by hermitcrab »

>"in typical Mail Online reporting style: "Did blunder by French airline spark air traffic control issues?"

The Daily Mail is a horrible, right-wing paper in the UK that blames 'foreigners' for everything. Particularly the French.

Out of curiosity, is there a corresponding French paper that blames the English or the British for everything?

Re: UK air traffic control meltdown

#198

Post by worik »

I heard in the news that this was caused by a "bad flight plan".

It is clear, even without any more information than that, it was a software failure (bad flight plan?)

It will be interesting to see if Frequentis has to pay a price for causing this

Re: UK air traffic control meltdown

#199

Post by cja »

Every system I've ever made has better error reporting that that one. Even those that only I use. First thing I get working in a new project is the system to tell me when something fails and to help me understand and fix the problem quickly. I then use that system throughout development such that it works very well in production. I'd love to talk to the people who made the system discussed in the article. Is one of them reading this? Can you explain how come this problem reported itself so badly?

Re: UK air traffic control meltdown

#200

Post by dboreham »

codeulike wrote: post #153

This is a great post. My reading of it: - waypoint names used around the world are not unique - as a sortof cludge, "In order to avoid confusion latest standards state that such identical designators should be geographically widely spaced." - but still you might get the same waypoint name used twice in a route to mean different places - the software was not written with that possibilty in mind - route did not compute…

"software supplier"??? Why on God's green earth isn't someone familiar with the code on 7/24 pager duty for a system with this level of mission criticality?
Post reply on HN