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Comment by twawaaay | Hacker News Reader

We rented an airbnb, very nice, very luxurious. Had motion activated lights everywhere. We slept with the light on because it malfunctioned and there was no physical switch to turn it off -- we actually called the owner and he said there is no need, "they will turn off automatically".

It is funny people can't envision things breaking...

(And before you ask, the light was in a corridor but there was no door to the bedroom. The switch was stuck on because it was broken not because it overlooked the bed -- it did not)

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> It is funny people can't envision things breaking...

This is what enraged me about the Therac-25 design which ended up killing people. There's a whole report to read on the design, failure and follow up but to paraphrase the designers eliminated the physical locking mechanism and had this attitude that "oh it's electronic so it won't wear out and fail".

Therac-25 https://en.wikipedia.org/wiki/Therac-25

Software errors killing people with excessive radiation doses.

It's a bit sad to see it coming up to regularly. On the one hand it's a very classic example of programming bugs leading to injury and death. On the other hand it's so long ago that bringing it up so often makes it seem like it's the only good example of dangerous software. Software must be pretty amazing and safe that we have to keep bringing up an example from the late 80s.

More that software that is critical is written with some level of care, and then never touched again out of fear of breaking it. See all the stories of hospital machines running windows xp.

That actually has a lot more to do with drivers not being provided by manufacturers for newer operating systems

It is useful to have a canonical example. Shared understanding of the problem, etc.

It’s related to why memes exist.

Uh, no. We have plenty of examples, they just don't kill people that often, because some industries learned their lessons.

If you want recent one, 737 MAX, killed way more than Therac-25. Although it was as much fault of software as suits around it wanting to save a penny on training, because if pilots knew about how it exactly worked they could've circumvented it

The software on the MAX worked as designed/specified; unlike Therac-25 there was no bug in the critical path, it was a series of design and oversight failures pushed by business and cost cutting interests, and the actual accidents were triggered (though I wouldn't consider it causal) by hardware failure in one of the AoA sensors. There was a bug regarding displaying an AoA disagree warning to the pilots, which despite being known wasn't fixed by Boeing, but this wouldn't have actually changed anything about the plane's behaviour.

To the credit of systems engineers, I can't think of a recent high profile fatal accident that could be reasonably blamed primarily on software, but that's not so much because software is infallible, but because systems are designed to fail safe.

Correct me if I’m wrong but wasn’t there an overflow in the software if the aircraft climbed too steeply ?

I’m sure I read that

The main bug was:

* each flight computer used its own angle of attack sensor with no way to detect failure. Craft had 2 sensors, but they were not used together (apparently that was extra paid option...) * pilots didn't know how the system worked or when it is active, so they were fighting against it

don't remember anything about overflow

I don't think so? Maybe a bug of this form was found, but I'm sure nothing like that was involved in the crashes. The flight control software performed as it was designed to, it wasn't software that sent the trim wheels spinning, but a bad AOA sensor and a lack of proper safety analysis, training and procedures.

There was a bug that caused the AOA DISAGREE alert on the EICAS not to be displayed, because at some point someone misunderstood the requirement that the AOA indicator should be hidden if they didn't pay for the upgrade, but this was just an indication and wouldn't have affected control at all (though likely would have hinted the pilots to a more appropriate cause of action).

One could also consider the lack of cross-checking between the two flight computers and associated AOA sensors to be a bug, but that was how the system was intentionally designed, because AOA wasn't considered a flight-critical measurement in the system's safety assessment, so they didn't consider this required. A holistic safety analysis was never really done inclusive of MCAS though, and this requirement probably just followed on from 737NG and wasn't really considered (at least thoughtfully...) in MCAS' design.

> Software must be pretty amazing and safe that we have to keep bringing up an example from the late 80s.

Or perhaps this failure settle the argument about whether or not physical lockouts were necessary and due to regulations you can no longer rely solely on software?

> but to paraphrase the designers eliminated the physical locking mechanism and had this attitude that "oh it's electronic so it won't wear out and fail".

And it would have been entirely fine if there was electronic safeguards put between code and rest of the device, just like some stop lights have it (if control board sends green signal to both directions it fails out and doesn't allow that). Defense in depth and all that

Covered really well in episode 39 of Causality, one of my favorite podcasts:

https://engineered.network/causality/episode-39-therac-25/

Each episode focuses on a root cause analysis of a major engineering disaster. Presented in a dry but engaging way - he's a good presenter, but none of the "Radio Lab" style nonsense.

Some fixtures may support yanking a bulb.

> It is funny people can't envision things breaking...

By comparison the Clap switch is so simple that if it is quite at least you can sleep at night

Take out the bulbs.

A lot of modern light fixtures have LEDs built in to the gadget, no separate "bulb".

Just turn it off at the fuse.

This reminds me a few years ago on a family holiday to malaysia I was sharing the room with my 10 year old cousin. I go downstairs to smoke suddenly his father calls me and tells me that my cousin called him crying in pitch black room as the lights went off. As he was lying on the bed reading a book motion censors did not detect any movement and the power cut off. Luckily he had his phone with him otherwise he would have been scarred for life. Why the fuck would they use motion censor for the light I would understand if they use it for the aircon or something but even then with the key card in the slot why would they set it like that.

> Luckily he had his phone with him otherwise he would have been scarred for life.

From the lights turning off? A ten year old?

Could be just a hyperbolic turn of phrase. The commenter may not be a native english speaker. The kid may have a developmental disability or a specific recent trauma related to this. Who fucking knows, it's none of our business. The story contributes to the discussion and makes its point either which way, what do you get from calling out this detail like this?

The parent may have a condition making him nitpicky, curious, and blunt (like Aspergers) or a specific professional or other curiosity related to this. Who fucking knows, what do you get from calling him out like this? See how it goes both ways?

Hehe, I very much do have a condition making me nitpicky and excessively curious! Thank you, your comment made me smile :)

FWIW I do have that condition as well, though it isn't usually called that these days.

What I gain from this is trying to move us away from comments that serve no purpose other than copy-editing each other and discouraging people from posting unless they can be confident in their adherence to the unwritten HN style guides. Which many people never can be, for various reasons.

If they had said that as part of a comment that overall served a different purpose I wouldn't have said anything. But it added nothing to this discussion except reinforcing the atmosphere that comments must be finely tuned to be taken seriously.

Yeah, the discussion could be kept more to the point. But it was a legitimate question for a sidenote - it's not like every subthread has to revolve around the original topic.

>FWIW I do have that condition as well, though it isn't usually called that these days

I know, never cared much for the politically and financially motivated rename, that imho blurs the condition across a larger area, instead of defining it better.

> Asperger was a member of a seven-member commission that was to categorize 200 disabled children according to their "educational ability" to decide their fate. 35 children were classified as "hopeless cases" and transferred to Spiegelgrund, where they all died. He was part of the legitimization of the murders and as an expert contributed to their categorization into "usefulness levels".

In this case since the guy it was named after would have killed me given the choice, I'm glad they renamed it. Good info about where you stand though, thank you.

>Good info about where you stand though, thank you.

You appear to stand in a worse place, implying people are Nazis because they're OK with using the traditional name for a condition, just because the person who did studied it had connections to them.

Your quick judgement of others, is worse than that - more Nazi-like in practical action, than some "association by name used for a condition" (which is no associatation at all). If I got power I'd be OK with some tainted names.

If you got power you'd classify people as enemies, or worse, based on such trivial matters as whether they prefer the older established name for a condition (and don't particularly care if we don't retroactively erase the person who discovered it from medical history for his crimes 80 years after the fact).

So a 10 year old in a foreign country in a room alone in pitch black dark for an hour or so won't get scared?. The room was pitch black we had checked in an hour or so ago so he was not even sure of where anything was in the room was. Though I confess part of the reason was his older siblings and cousins had been telling ghost stories the previous night.

You said "I go downstairs to smoke" and now you say "for an hour or so". I don't know your smoking habits, but isn't this a little unusual?

I don't think I've ever been in a "pitch black" hotel room. I'd bet there was light enough for him to start seeing just fine after five minutes.

The ghost stories, sure. But then he's scarred for life more by the ghost stories rather than by the lights turning off...

But the point of the anecdotal story was using automation wrongly why would you care about the turn of phrase I used

Sure agreed that automation is often pointless and more harmful than helpful. I'm just surprised you're making such a fuss about a ten year old in a dark room.

> I'm just surprised you're making such a fuss about a ten year old in a dark room.

Pretty sure that was just being used as an example to underscore a broader point. No need to nitpick.

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