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German Police Admit That Full Body Naked Airport Scanners Suck; 35% False Alarm Rate

from the that's-worse-than-useless dept

We've noted all sorts of privacy and health problems related to full body "naked" scanners -- but there's a separate but important question: do they actually work? There's been some evidence presented that they wouldn't have spotted a variety of recent terrorism attempts, but now German police have noted that the machines also have a ridiculously high false alarm rate:
The weekly, Welt am Sonntag, quoting a police report, said 35 percent of the 730,000 passengers checked by the scanners set off the alarm more than once despite being innocent.

The report said the machines were confused by several layers of clothing, boots, zip fasteners and even pleats, while in 10 percent of cases the passenger's posture set them off.

[....]

In the wake of the 10-month trial which began on September 27 last year, German federal police see no interest in carrying out any more tests with the scanners until new more effective models become available, Welt am Sonntag said.
I would argue that this is actually worse than useless, in that providing a significant number of false positives makes it much, much harder to spot the actual positives. It desensitizes agents to assume that any alarm is a false alarm.


Reader Comments (rss)

(Flattened / Threaded)

  1.  
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    ahow628 (profile), Aug 9th, 2011 @ 7:32am

    What do you want to bet?

    I bet none of the body scanning makers are major contributors to German re-election campaigns.

    On the other hand, you know there was major lack of due diligence from the US government because of some lucrative government contract farmed out to a major campaign supporter.

     

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  2.  
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    Donnicton, Aug 9th, 2011 @ 7:41am

    while in 10 percent of cases the passenger's posture set them off.

    That's just because there haven't been any courses that teach children proper posture anymore.

    I'm sure if we mandated a "government approved posture program", we will see a sharp drop off in false positives due to posture.

     

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  3.  
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    Ninja (profile), Aug 9th, 2011 @ 7:57am

    Re:

    That's a public health issue. We should get more money from the Health Ministry so we can make scanners that will ignore the bad posture numbers and thus cover the terrible German health service. Oh.. We were talking about security?

     

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  4.  
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    specialized (profile), Aug 9th, 2011 @ 8:00am

    I can picture it now, a 21st century re-boot on everybody's favorite fable, "The Boy Who Cried Wolf."

    The Full Body Naked Scanner that Cried Terrorist.

     

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  5.  
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    FormerAC (profile), Aug 9th, 2011 @ 8:01am

    more than once?

    "The weekly Welt am Sonntag, quoting a police report, said 35 percent of the 730,000 passengers checked by the scanners set off the alarm more than once despite being innocent"

    How many set it off only once, despite being innocent?


    "they trigger an alarm unnecessarily in seven out of 10 cases"

    Is that seven out of ten passengers screened set off an alarm unnecessarily? Or only that 70% of the alarms are false alarms?

     

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  6.  
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    Beta (profile), Aug 9th, 2011 @ 8:04am

    dream job

    I would love to be the official in charge of investigating how these machines were bought, installed and put into operation before these tests were carried out, and whose signature was at the bottom of all the documents.

     

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  7.  
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    John Doe, Aug 9th, 2011 @ 8:09am

    Just like the alarms at the exit doors of Wal-Mart

    The exit doors at Wal-Mart have a scanner that rarely goes off, but when it does, the employees often times just go over and reset the alarm without checking the person who set it off. Seems there are enough false alarms they consider every alarm a false one.

     

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  8.  
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    Anonymous Coward, Aug 9th, 2011 @ 8:15am

    Well, now, let's see. 35%? I would have to imagine that the machines have some parameters for tuning, and perhaps the German units are set to be very sensitive. Are you sure the US units are used the same way?

    What are the standards for a false alarm? The unit blocking an area for further checking? Hmmm, that sounds more like "areas that the machine can't accurately check that require manual inspection" rather than a false alarm.

    Is there like lights and a siren and stuff, or just an operator going "check this person some more"?

    Mike, I know you want these machines to go away, but can you please at least try to not over-hype everything negative you read about them?

     

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  9.  
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    freak (profile), Aug 9th, 2011 @ 8:17am

    Re: Just like the alarms at the exit doors of Wal-Mart

    With the wal-mart here, it's because the employees are not allowed to accuse the person of stealing, indicate they might be stealing, or even confront someone they think might have set the alarm off by saying: "I think you might have set the alarm off".

    I have no idea why they even have an alarm if they're not allowed to do anything about it ...

     

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  10.  
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    Vincent Clement (profile), Aug 9th, 2011 @ 8:20am

    The fact that the Israeli Airport Authority does not use body scanners is the best indicator of their value.

     

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  11.  
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    Joe Publius (profile), Aug 9th, 2011 @ 8:27am

    Re: Re: Just like the alarms at the exit doors of Wal-Mart

    As a former retail drone, I get the impression that all of the precautions taken against shoplifing are essentially security theater.

    You really can't accuse someone of stealing, but the alarms, the aisle walks, etc exist to give lifters the impression that they are being watched.

     

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  12.  
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    AdamBv1 (profile), Aug 9th, 2011 @ 8:27am

    Re: more than once?

    That seems to be what I'm reading.

    "Their biggest drawback is the so-called alarm rate. It lies, as it says in the "Welt am Sonntag" this confidential report, at 70 percent. In other words, in two out of three controlled passengers struck the detector."

    http://translate.google.com/translate?hl=en&sl=de&u=http://www.welt.de/politik /deutschland/article13516870/Der-Pannenscanner-viel-Kleidung-viel-Alarm.html

     

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  13.  
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    AdamBv1 (profile), Aug 9th, 2011 @ 8:32am

    Re:

    It basically means that 70% of the people who pass through these scanners get a false positive and since they say that 35% of the people passing through these scanners set off multiple false positives it seems the immediate recourse to a positive scan is another dose of rads. Once you get that second false positive it would seem you get a manual pat down.

     

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  14.  
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    freak (profile), Aug 9th, 2011 @ 8:32am

    Re: Re: Re: Just like the alarms at the exit doors of Wal-Mart

    With any other store I've been to, they actually do use those features to catch AND charge people.
    Strangely enough, it doesn't hurt business to kick out those folks who were costing you money every visit. Who knew?

    It doesn't surprise me that wal-mart has such a high shoplifting rate . . .

     

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  15.  
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    Pitabred (profile), Aug 9th, 2011 @ 8:34am

    Re: Re: Just like the alarms at the exit doors of Wal-Mart

    Only their "loss prevention" team is allowed to do that. The general employee just needs to ignore it.

     

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  16.  
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    Anonymous Coward, Aug 9th, 2011 @ 8:41am

    Re:

    Yup, they just use techniques that would violate pretty much all of the US constitution, plus large guns on board most of their flagship airlines flights.

    Yeah, somehow I think a pat down is better than giving up all my rights.

     

    reply to this | link to this | view in thread ]

  17.  
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    Clay, Aug 9th, 2011 @ 8:42am

    Re:

    I'm sure if we mandated a "government approved posture program", we will see a sharp drop off in false positives due to posture.

    Well said comrade.

     

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  18.  
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    Nicedoggy, Aug 9th, 2011 @ 8:43am

    Re: Re: Just like the alarms at the exit doors of Wal-Mart

    The testing phase perhaps?

     

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  19.  
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    Theoden, Aug 9th, 2011 @ 8:45am

    Re: What do you want to bet?

    Reminds me of the way the Electronic Voting machines were pushed out to the polls with no way to verify anything that they did.

    Receipt? We don't give no steenkin' receipts!

     

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  20.  
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    Anonymous Coward, Aug 9th, 2011 @ 8:55am

    Re:

    What are the standards for a false alarm? The unit blocking an area for further checking? Hmmm, that sounds more like "areas that the machine can't accurately check that require manual inspection" rather than a false alarm.


    That's the same thing as a false alarm as the machine identifies suspicious items or areas. It's not a "bomb" or "gun" detector, it's a detector of odd stuff.

    Regardless, the machine is looking for something that is present on a very small fraction of the people checked. If it identifies 1:3 as being possible violators, it is useless. False alarm rate is very important for sensors/detectors, especially those looking for rare things. Almost every single person who sets the machine off is innocent, so the alarm means nothing.

     

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  21.  
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    Richard (profile), Aug 9th, 2011 @ 9:00am

    Re:

    One if a series that also includes:

    The Emperor's new Blocking System

     

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  22.  
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    Anonymous Coward, Aug 9th, 2011 @ 9:04am

    The germans don't know how to use the machines properly like the americans do.

    You are supposed to strip down to almost naked BEFORE going into the naked body scanners.

     

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  23.  
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    Richard (profile), Aug 9th, 2011 @ 9:06am

    Re: Just like the alarms at the exit doors of Wal-Mart

    The exit doors at Wal-Mart have a scanner that rarely goes off, but when it does, the employees often times just go over and reset the alarm without checking the person who set it off. Seems there are enough false alarms they consider every alarm a false one.

    This is also what happened at Chernobyl.

     

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  24.  
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    Ninja (profile), Aug 9th, 2011 @ 9:19am

    Re: more than once?

    35% of the 730k surveyed triggered the alarm more than once despite being innocent.

    10% of the total triggered the alarm because of bad posture.

    70% of the cases where the alarm triggered were false positives.

     

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  25.  
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    Casey Mahoney (profile), Aug 9th, 2011 @ 9:39am

    Why

    Why things are not tested out before hand.I would hate to be a TSA person these days.You might get hit or punched.

    Thanks Casey Mahoney

     

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  26.  
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    geekwithsoul (profile), Aug 9th, 2011 @ 10:28am

    So if there are false positives . . .

    does anyone know the rate for false negatives? If that's higher than a few percent, you kind of have to wonder what the whole purpose of this approach is.

     

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  27.  
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    Urza9814, Aug 9th, 2011 @ 10:47am

    Re: Re:

    The government has already stated that your constitutional rights do not apply at airports. That's how they can get away with the pat-downs and such...

     

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  28.  
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    Jeffrey Nonken (profile), Aug 9th, 2011 @ 11:01am

    Makes me think of store security scanners...

    You know, those silly things they put on either side of the door that beeps when it sees a security strip that hasn't been zapped? It's funny to watch the clerks in a store when the alarm goes off -- they don't even look up. Somebody could be taking the entire liquor aisle and they wouldn't notice.

    "The Boy who Cried Wolf" is more than 2500 years old and is embedded in our culture, even to having its own idiom, and we haven't figured it out yet. Well, it looks like the Germans have. I guess we're not as smart as they are.

     

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  29.  
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    Leo, Aug 9th, 2011 @ 11:15am

    Re: So if there are false positives . . .

    Well...
    If I remember correctly, only one terrorist attempt has been made in a plane since the porn-scanners are in use. This terrorist was captured on the plane, not by the scanner.

    Terrorists might have been captured by the scanners before boarding the plane. But I never heard about this. And whatever the number, it is vanishingly small compared to the number of normal passengers just flying from A to B.

    The number you are looking for is either 100% or incomputable.

     

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  30.  
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    Prisoner 201, Aug 9th, 2011 @ 1:10pm

    Re:

    Almost?

    Clearly you did not get the latest memo on "standard procedures".

     

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  31.  
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    BeeAitch (profile), Aug 9th, 2011 @ 3:48pm

    Re: Re:

    So, you'll happily give up some of your rights as long as you're not asked to give up all of them.

    Then, by your argument, your rights can be stripped until you only have one right left.

    The million-dollar question: Which right do you choose to keep? (And do you really believe that you'd be allowed to choose?)

    I don't like you world...

     

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  32.  
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    aldestrawk (profile), Aug 9th, 2011 @ 11:08pm

    Re: more than once?

    Unless, this is being misreported by the media, a false positive rate is a percentage of all passengers screened and is independent of the rate of terrorists bringing weapons or explosives on board. There should be very very few true positives and unless they are an intentional test, the discovery will be publicized.

     

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  33.  
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    aldestrawk (profile), Aug 9th, 2011 @ 11:32pm

    Re: So if there are false positives . . .

    That rate is probably considered SSI, if not classified. A general target range for both FAR and FRR in security detection scanners is given as 1%-5%
    http://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_rpt_86v13.pdf

     

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  34.  
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    Hans, Aug 10th, 2011 @ 9:22pm

    Re: Re:

    "Yup, they just use techniques that would violate pretty much all of the US constitution,..."

    Citation please.

    "... plus large guns on board most of their flagship airlines flights."

    Sounds like an excellent deterrent.

    "Yeah, somehow I think a pat down is better than giving up all my rights."

    Yeah, somehow I think that there's no reason for me to lose my rights in order for you to have the illusion of security. If you're worried about flying, then don't fly. But don't expect all the rest of us to get scanned or groped so you can feel better.

     

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  35.  
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    steve2, Nov 5th, 2011 @ 11:04am

    The scanners give off radiation which makes them a health risk. We aren't being kept safe if we're being hit with radiation. There's already a million sources of radiation in society. Cell phones, laptops, and flatscreens are a few sources. There's many others. We don't need these scanners that aren't even reliable to damage us with more radiation.

     

    reply to this | link to this | view in thread ]


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