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Comment by nlawalker | Hacker News Reader

Let me get this straight. If the article is correct, the new capabilities are related to better detection of large liquid containers, not determination of whether or not the liquid is dangerous.

So - you couldn’t take large amounts of liquids previously because some liquids in large amounts might be able to be weaponized. If you were caught with too much liquid (in sum total, or in containers that are too large) they’d throw it out and send you on your way.

But now that they have the ability to detect larger containers, they… do what? Declare that it’s safe and send you on your way with it still in your possession?

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Dublin has been relaxing their restrictions for a while now, and when I travelled two weeks ago, had also completely dropped the rules. You no longer need to remove liquids or electronics from bags, and the liquids per bottle limits are much higher (don’t remember exactly, maybe 2 litres) with no restriction on total number of bottles.

I watched a YouTube video about it a few months back and apparently the new devices, at least those used in Dublin, are much more accurate in detecting the difference between materials that previously looked similar to the machines, they can also rotate the images in 3d to get a look from different angles. Both of these make it easier to tell whether a substance is dangerous, apparently.

Berlin had a mix of modern scanners and old scanners last time I flew. I had one flight where they were using the modern scanners. And then a few weeks later I used a different security gate and I still had to remove everything from the bag. If you fly from there, the security at the far end of the terminal has the new machines and is usually also the fastest because people generally use the first security gate they see. Good tip if you are in a hurry. The last few times I was through in a few minutes.

At some airports, you can now check your own bag using a machine that weighs it and prints a sticker. Then you drop it on a belt yourself and you walk through security scanners; all without having to talk to anyone. And finally you board using your phone. Lots of automated checks. I've boarded a few times now without anyone bothering to look at an id now. It seems that with self check in the id check at the gate disappeared. And inside the Schengen zone, nobody checks ids at security either.

Edinburgh dropped all liquids and electronics ceremony for a few months now. It's great. I have found that adds of your bag being put aside for further insepction seems to have increased though.

When you don't know much about a topic, probability is higher that your are missing some piece than some entity doing things that make no sense.

I know it's easy to get the impression that's not the case. But when your stop making fun of / belittle such events / persons / decision and be curious instead you start to realize that more often than not you are just missing a piece of information.

The truth oftentimes is just not interesting enough and not clickbait worthy.

You’re right. I am genuinely curious though, so I shouldn’t have been so snarky about it. I’ll try again:

I’ve always been under the impression that large containers of liquids were forbidden because they were potentially dangerous. If that hasn’t changed, and if the new technology is only about being able to better detect the presence of liquids in packed luggage, why have the limits on container size changed?

EDIT: So I see that the article says that it’s about being able to keep the liquids in your bag when going through security. But I thought liquids in large containers were forbidden from going through security entirely unless you had some kind of medical justification for them?

Not just the presence but the material itself: https://www.smithsdetection.com/products/sdx-10060-xdi/

It’s X-ray diffraction

I believe the article mentioned density as well. I suspect that is extremely key in determining what it is, or at least determining if it is something really odd that should get additional screening.

So they'll still make me toss out my dang sunscreen.

No, they'd make you take it out if the scanner / person is unable to classify the object.

It's not just large amounts of liquids: it was my understanding that this is both a restriction on large amounts of liquid, but particularly on large containers needed for an explosive of sufficient destructive power.

You could always easily work around the liquid amount restriction (multiple containers over multiple people), but if you still need a large container, it becomes harder.

I don't know if this is true or if a resealable plastic bag also works, for instance (that would be funny, wouldn't it?).

This might make sense if there weren't shops selling large bottles right after security. Ones full of highly flammable liquids, even.

Like what? Alcohol isn't flammable unless it's over 63%, and you aren't allowed to bring duty free alcohol on the plane.

Duty-free purchases are all hand carried into the aircraft, and "tamper-proof" bags are nothing of the sort.

Tamper evident, a very different thing.

Alcohol is flammable around 40%. French cooks aren’t using overproof brandy to do flambé.

Gunpowder doused in alcohol is, very famously for people interested in the history of rum, flammable if the alcohol is around 57.1% or higher, but straight alcohol/water without gunpowder is flammable at a lower strength than that.

Or if you couldnt simply take a large empty bottle through.

Howver if you rely on 10 people to take 100ml each that’s a far larger conspiracy and far less likely than one person taking 1l through.

I am not sure any of it makes real sense, it's just a variation of the "why" I picked up somewhere (that it's both).

But yes, that's easily worked around in the manner people brought up already (I did think of duty free bottles, but not camera cases, that is a good one).

>particularly on large containers

It's common for people to carry large metal equipment cases (for cameras, etc.) onboard

It can detect not only large containers of liquids, but (up to a point) what liquid is in them.

Have you never been screened where they swab your items and stick it in a machine? That is to detect explosives. They can use the first machine to target people for follow up screening.

I have, but what’s relevant is that I’m always commanded to dump out any liquids in containers bigger than the 3.4 oz limit before going through security unless they’re like a prescription medication. What I’m unclear on why that’s changed if the improvement that’s been made is in detection of liquids in packed bags.

So far, this machine has been used to reliably, 10/10 times, reject and discard my nivea deodorant.

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