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Getting knives past airport security seems not particularly difficult from the experience of my circle and other anecdotal sources. I've had friends and family accidentally get knives through security on many occasions, and I have also accidentally done it myself. To my knowledge none of them has ever been caught in the converse situation and had to give up a knife.

I imagine if one were resourceful and deliberate about it, it would be even more successful.

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This would be great for ML. A knife detection algorithm that alerts the officer when it thinks it spots one when the bags go in the scanner.

Except then you get delayed because the model decides you have a knife and "the computer can't be wrong".

They search people randomly anyway, and they search people if the human operator thinks they see something suspicious. If we can keep the number of searches constant and just increase the probability of finding a knife, it's a win for everyone.

It's obviously not a win if there's too many false positives, but it's worth a try.

Is it a win for everyone though?

If we have X cases where people brought knives onto planes, and no notable incidents of knife-enabled violence in the past few years, what's the motivation for reducing X by half?

I'm sure that some would-be-criminals are dissuaded by the TSA, but that seems to already be working today. It seems like a very reasonable outcome would be no decrease in airline violence/crime, but an increase in taking people's property.

All said, if there is still a scourge of knife-wielding criminals on airlines, I'd be happy to be wrong here. Otherwise, though, this seems like it have a very marginally negative impact on the average passenger by taking away their belongings that they accidentally packed.

Great point! Although I'd think P(knife hijacking)*Cost(knife hijacking) would be much much larger than the cost of knives being confiscated, even if P(knife hijacking) is very small, just given how cheap knives are and how big that Cost is. I think the bigger point is how much the software would cost and whether the reduction in X justifies that expenditure. Also need to consider cost savings of being able to fire some TSA staff. That reduces the theatre aspect perhaps, but maybe not if it's done the right way (I can think of a few ideas)

The scenario I see:

Joe McRandom is heading through TSA, and is falsely flagged as having a knife by this software.

Because the computer _can't_ be wrong - a depressingly common view among anyone who doesn't work with computers regularly - the TSA agent flags our friend Joe. Joe's entire luggage is then unpacked, in front of everyone present - hope he didn't have anything sensitive in there!

When he inevitably does not have a knife in his luggage, the TSA agent spends way too much time searching for the secret compartment, as well as digging through all the stuff. When there is _still_ no knife to be found, Joe is taken into custody - we've already seen that airport security can be trusted to abuse their power - causing Joe to miss his flight, be psychologically damaged (I'd be pretty shook up after that degree of search and detainment), and possibly lose his luggage (better hope the TSA did a good job keeping track of it, and decides you deserver to have it)!

Is this situation likely, strictly speaking? Over the massive number of TSA agents working and travel being done, I would say yes. All of the negative effects of the TSA mentioned above already happen, a system like this just makes it more likely to be occur for no real reason.

Also, while the average knife may not be expensive, some are. On top of that, many who carry knives form emotional attachments to them, so even if there's no "real" damage being done, there is some amount of harm being done in a much harder to quantify way.

It wouldn’t be a hacker news post if ML didn’t theoretically solve a problem.

I was going to put a disclaimer because of the risk of sounding cliche/ironic/sarcastic, but figured it was a legitimately good idea so I decided to spare people.

Ceramic knives sold to the general public are supposed to have a metal core to make them detectable.

All ceramics are available for people (police, military) who need a hard to detect self-defence knife, eg:

https://gearward.com/products/ceramic-escape-knife

People should be terrified that the "undetectables" are reserved only for the "authorities".

Ceramic knives seem quite fragile in the kitchen, I am skeptical they have a lot of potential as weapons, as even small amounts of twisting/shearing force will crack or snap them.

> Getting knives past airport security seems not particularly difficult from the experience of my circle and other anecdotal sources. I've had friends and family accidentally get knives through security on many occasions, and I have also accidentally done it myself. To my knowledge none of them has ever been caught in the converse situation and had to give up a knife.

May I ask what your race, and the race of your circle, is?

I am white but with black (and now slightly grey) hair and a beard with tan-ish skin. More pertinent to your implication I assume is that my middle name is of Muslim descent and can pass for being of middle-eastern descent, and I seem to get stopped for "random" checks and patdowns more frequently than my white-bread looking friends and colleagues. Observation bias perhaps on my part, but also maybe not.

I've accidentally gotten multi-tools through the body scanner before. I just forgot I had it in my pocket.

Are you suggesting that metal detectors are racially biased?

No. I am suggesting that the discretion of airport security staff about whom to pay closer attention to is. And my suggestion is known as 'profiling'.

Generally, once you get through the metal detector, the knife that was accidentally smuggled through won't be found by a simple body search, if that's your inclination?

This happened to my friend (not White if that's so important to you) when an old pocket knife had gotten stuck beneath the bottom of her handbag. They kept running it through the detector, took everything out of it to check, couldn't find the source, and so eventually let her go.

I've had TSA confiscate my mini swiss knife (1 inch blade)... #-/

I've had to give up a knife on two occasions.