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Why airplane bathrooms have ashtrays

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Re: Why airplane bathrooms have ashtrays

#141

Post by [deleted] »

corin_ wrote: post #77
lflux wrote: post #72

Earlier quoted context omitted.

Fire hazard maybe? Trash cans were removed from commuter trains in Stockholm since they were constantly being set on fire. They're on our buses though. Go to England and you won't see trash cans in train stations at all.

In England we do have bins in stations, but now days they generally consist of a transparent bin bag with no surrounding material (e.g. held open by a loop at the top that's attached to a wall). I believe the logic is that it makes it harder to hide a bomb in them, though whether this is fact or just commonly quoted myth I have no idea.

[deleted]

Re: Why airplane bathrooms have ashtrays

#142

Post by sopooneo »

Zak wrote: post #25
mikeash wrote: post #17

Earlier quoted context omitted.

Because, although it could bring down a plane, it's very likely not to. The fire will be detected quickly and then put out. Your question is sort of like asking, if an airliner can fly on one engine, why do they bother putting on two? The answer, quite simply, is robustness.

The other reason for it is to make people feel safer about flying on planes. I think it has long outlived its usefulness for that purpose, but that may be my bias toward rationality speaking.

I always assumed the reason for the intrusive security checks was that at some high level, our government felt another terror attack was very likely, and they didn't want anyone to be able to say they weren't doing anything after it happened again. So perhaps it is to prevent rioting in the streets after an attack as much as to prevent the attack itself.

Re: Why airplane bathrooms have ashtrays

#143

Post by abduhl »

WalterBright wrote: post #128
GoodIntentions wrote: post #102

Earlier quoted context omitted.

>> Fukishima plant Actually it sounds like the plant failed due to some poor - in retrospect - design assumptions. The generators required to keep cooling systems running safely were buggered by the same disaster. "fail-over" - they got it half right.

The problem is when the backup system is not independent of the primary, so one failure takes out the other. When I read about the step-by-step domino sequence of failures in the plant, the design was clearly deficient. The erroneous thinking was "the tsunami wall cannot fail". The correct thinking is "what happens when the tsunami wall is breached? what happens to the plant? how can the plant withstand that?" For ex…

I don't know what your background is but, based on your post, I am assuming it is not in civil or mechanical engineering. Please excuse me if I'm wrong.

The design of this power plant probably went like most designs in civil engineering where extreme design loadings were defined (500-year quake, 100-year flood, etc.) and the plant was designed to meet the loads that would be imposed by the most critical event. For a critical piece of infrastructure these loading conditions are quite stringent. While these loadings drive the design at one end, budget drives the design at the other. Most civil projects tend to be just safe enough and not more. This leads to the realm of acceptable risk/failure. The tsunami wall failing under a 1000-year quake is an acceptable failure. The backup systems were most likely designed for progressively lower degrees of acceptable failure. At some point though it becomes too costly to over-design.

Was hardening the backup generators against flooding "not difficult nor expensive"? I can't tell you that, I didn't design it. Based on the fact that they weren't hardened, I would say that it probably was difficult or expensive.

Would placing the backup generators off site be a better idea than having them on site? Possibly. Possibly not. Every meter you move the generators away from the plant is another meter's worth of risk. How many redundant transmission lines do you need for a generator a mile away? How many redundant generators do you need now that you have the added risk of possibly losing a generator's transmission lines?

Contrary to common belief, public works projects do not have an infinite budget. On top of this, working with municipalities generally results in ridiculous amounts of regulations regarding pricing, reviews, and permitting. While this maintains a minimum standard for designs, it also drives all designs down to that minimum standard. It is simply too costly to continually design for more and more unlikely events.

Users of this site should be well familiar with this based on the number of Internet Explorer compatability comments I've read lately.

Re: Why airplane bathrooms have ashtrays

#144

Post by brc »

Turing_Machine wrote: post #18
brc wrote: post #5

That's interesting news to me. I did wonder why smoking paraphernalia continued to appear in planes that were covered in anti-smoking insignia. I always assumed that the bathrooms, seat etc were made in large quantities, and that there are a lot of countries in the world where you can still light up in a flight, not to mention privately owned planes. I once flew on a Japan Air Lines flight back in the '90s. At that s…

"The fire risk alone should immediately discount it." A quick Google turns up only two airline accidents possibly attributed to cigarettes (a 1982 Illyshin IL-18 crash in Guangzhou, China and a 1973 crash in France). Pretty minimal, given that smoking was allowed on millions of flights for close to 90 years.

That's two more crashes than is necessary if you ask me. You're not allowed to take firecrackers on a plane, and there probably isn't any recorded crashes from firecrackers.

Besides, you don't need to crash a plane to make it a bad idea. Just damaging it or creating a smoke filled (as in burning material, not cigarettes) interior is bad enough.

I can see how you might think it's OK if you're a smoker, but I'm happy that there isn't any smoking.

Re: Why airplane bathrooms have ashtrays

#145

Post by WalterBright »

abduhl wrote: post #143
WalterBright wrote: post #128

Earlier quoted context omitted.

The problem is when the backup system is not independent of the primary, so one failure takes out the other. When I read about the step-by-step domino sequence of failures in the plant, the design was clearly deficient. The erroneous thinking was "the tsunami wall cannot fail". The correct thinking is "what happens when the tsunami wall is breached? what happens to the plant? how can the plant withstand that?" For ex…

I don't know what your background is but, based on your post, I am assuming it is not in civil or mechanical engineering. Please excuse me if I'm wrong. The design of this power plant probably went like most designs in civil engineering where extreme design loadings were defined (500-year quake, 100-year flood, etc.) and the plant was designed to meet the loads that would be imposed by the most critical event. For a…

My background is I am an ME and I worked on designing flight critical systems on airliners. I had the philosophy of designing to survive failure hammered into me, and when I see the Fukishima plants, all the red flags go up in my head.

For example, let's assume the wing spar fails. Junior engineer says "but the spar can't fail! We designed it to handle any predicted load!". Senior engineer says "Wrong answer. Anything can fail. How will you design the airplane to survive a wing spar failure?" (The solution usually is to have dual wing spars.)

This question is repeated for every single system and part in the airplane. Failure scenarios are also played out to ensure that failure of one part or system will not have a "zipper" effect of breaking other critical systems.

With Fukishima, I clearly see "the sea wall cannot fail, so we won't even bother to investigate if we can make failure of the wall survivable."

As it turned out, it would have been survivable if only the backup generators hadn't failed due to flooding. Hardening those generators (one way) is to simply put them in a concrete box. It's hard to believe that would have been that expensive. Videos of the tsunami showed a lot of masonry structures withstanding it.

> How many redundant transmission lines do you need for a generator a mile away?

Good question. The general rule is to have an independent backup system for every critical system. That has made flying around the world in an airliner safer than driving yourself to the post office.

Re: Why airplane bathrooms have ashtrays

#147

Post by pbhjpbhj »

jasonkester wrote: post #67
snowwrestler wrote: post #64

The illustration of the door handle is a great example of piss-poor affordance. A slight ridge is not going to clearly communicate push vs. pull. Especially since our fingers, when gripping, actually like a ridge to fill in the open angle behind the first knuckles. If you want someone to push, give them a big fat flat metal plate or bar to push on. If they can't pull, they are guaranteed to get it right every time. I…

The door handle could actually be described as an anti-affordance. I looked at the photo and thought to myself what a great idea it was that it gave you a comfortable ridge for your knuckles while pulling and a nice rounded bit (instead of a sharp-edged flat surface) to push on. That is, it signalled to me the exact opposite of the designer's intended use. I would have been doubly surprised if pulling on that clearly…

Me too. Did the blogger just label it wrongly?
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