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UK air traffic control meltdown

jameshaydon.github.io

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Re: UK air traffic control meltdown

#381

Post by pmontra »

crabbone wrote: post #258
pmontra wrote: post #186

Earlier quoted context omitted.

A customer of mine is adamant in their resolve to log errors, retry a few times, give up and go on with the next item to process. That would have grounded only the plane with the flight plan that the UK system could not process. Still a bug but with less effects to all the continent, because planes that could not get inside or outside the UK could not fly and that affected all of Europe and possibly more.

> That would have grounded only the plane with the flight plan that the UK system could not process. By the looks of it, it was few hours in the air by the time the system had a breakdown. Considering it didn't know what the problem was, it seems appropriate that it shut down. No planes collided, so the worst didn't happen.

Couldn't the outcome be "access to the UK airspace denied" only for that flight? It would have checked with an ATC and possibly landed somewhere before approaching the UK.

In the case of a problem with all flights, the outcome would have been the same they eventually had.

Of course I have no idea if that would be a reasonable failure mode.

Re: UK air traffic control meltdown

#382

Post by krisoft »

NovemberWhiskey wrote: post #177
tpmx wrote: post #152

Earlier quoted context omitted.

I think that term was invented four days ago by that article writer. There are four other occurrances before then and they're about PS2 games.

This term was in wide circulation when I was consulting at NATS in the 2000-2005 time frame.

That is indeed very currious. So you say NATS was amaware of this vulnerability?

Re: UK air traffic control meltdown

#383

Post by darkclouds »

splonk wrote: post #362
darkclouds wrote: post #319

Earlier quoted context omitted.

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 ma…

Airline employees routinely turn people away at the departure airport due to visa/passport paperwork not being in order. Timatic is the usual system that most airlines subscribe to for this kind of thing. Airlines are highly incented to avoid letting a passenger board who won't be admitted, because they're on the hook for returning that passenger. But an airline employee in at the departure airport is never going to…

So how do they spot the fake passports then?

And is this a legal on the hook for returning passengers that are not allowed in the destination country?

I've got caught in the US when Hurricane Katrina was landing, and whilst we were flown out by our carrier, other carriers in this situation would also honour our ticket and fly us back to the UK.

It seemed like an exodus where all the carriers just got people out of the country as quickly as possible. We were on the last flight out of the airport, but this isnt a legal thing is it?

Re: UK air traffic control meltdown

#384

Post by zarzavat »

moritzwarhier wrote: post #285
codeulike wrote: post #279

Earlier quoted context omitted.

If two waypoints have the same name assume its the closest one to the adjacent ones in the route-chain rather than the one 4000 km away

Sounds like a helpful idea with considerable implementation complexity, including the potential for new disastrous failure modes.

Not really because each point is only adjacent to a small neighborhood of other points, so if you want to test every possibility then your search space only grows by a constant factor proportional to the maximum degree of the graph.

As for implementation complexity, you would hope they would use formal verification for something like this.

Re: UK air traffic control meltdown

#385

Post by codeulike »

moritzwarhier wrote: post #285
codeulike wrote: post #279

Earlier quoted context omitted.

If two waypoints have the same name assume its the closest one to the adjacent ones in the route-chain rather than the one 4000 km away

Sounds like a helpful idea with considerable implementation complexity, including the potential for new disastrous failure modes.

But its how the waypoint codes work in practice - they are contextual. If Air Traffic Control tell a plane to head for waypoint RESIA, they mean the one nearby, not the one 4000 km away.

Re: UK air traffic control meltdown

#386

Post by DocTomoe »

dhx wrote: post #335
WalterBright wrote: post #322

> the backup system applied the same logic to the flight plan with the same result Oops. In software, the backup system should use different logic. When I worked at Boeing on the 757 stab trim system, there were two avionics computers attached to the wires to activate the trim. The attachment was through a comparator, that would shut off the authority of both boxes if they didn't agree. The boxes were designed with:…

This would have been a 2oo2 system where the pilot becomes the backup. 2oo2 systems are not highly available. Air traffic control systems should at least be 2oo3[1] (3 systems independently developed of which 2 must concur at any given time) so that a failure of one system would still allow the other two to continue operation without impacting availability of the aviation industry. Human backup is not possible becaus…

> Human backup is not possible because of human resourcing

This is an artificial restraint. In the end, it comes down to risk management: "Are we willing to pay someone to make sure the system stays up when the computer does something unexpected?".

Considering this bug only showed up no, chances are there was a project manager who decided the risk would me extremely low and not worth spending another 200k or so of yearly operation expenses on.

Re: UK air traffic control meltdown

#388

Post by f1shy »

WalterBright wrote: post #322

> the backup system applied the same logic to the flight plan with the same result Oops. In software, the backup system should use different logic. When I worked at Boeing on the 757 stab trim system, there were two avionics computers attached to the wires to activate the trim. The attachment was through a comparator, that would shut off the authority of both boxes if they didn't agree. The boxes were designed with:…

I would be very interested in knowing which languages were used. Do you know which were? Thanks

Re: UK air traffic control meltdown

#389

Post by shatnersbassoon »

WalterBright wrote: post #322

> the backup system applied the same logic to the flight plan with the same result Oops. In software, the backup system should use different logic. When I worked at Boeing on the 757 stab trim system, there were two avionics computers attached to the wires to activate the trim. The attachment was through a comparator, that would shut off the authority of both boxes if they didn't agree. The boxes were designed with:…

"When a failsafe system fails, it fails by failing to fail safe."

J. Gall

Re: UK air traffic control meltdown

#390

Post by fennecfoxy »

"UK air traffic control: inquiry into whether French error caused failure"

Of course bloody not. How is it a French airline's fault when it's a UK system? Systems like this should be foolproof with redundancies.

If one entry is bad reject it and carry on, even.

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