Why does the TSA love my left ankle?

August 19, 2017 5:23 PM

I fly 1-2 times a month, and I generally go through the millimeter wave scanner. 87% (yes I've tracked and calculated!) of the time I've gone through the scanner in the past year and a half, I have been asked to step aside so an agent can pat down the back of my left ankle. I have no idea why! Do any folks familiar with how this works have any idea why the machines might be flagging that specific part of my body so reliably? Answers to your immediate questions inside...

I don't wear jewelry on my ankle.
It happens whether or not I'm wearing wear socks.
I am almost always wearing bootcut jeans, but not always the same brand or style.
I do have a vibrantly-colored tattoo on the inside of that ankle--but I also have a large, colored tattoo on my back and that never gets flagged for patdown.
I have no visible scars or marks on my ankle other than the tattoo.
It happens at all the airports I usually fly through, though much less often at PDX than DEN and SFO.
I only started noticing it about a year and a half ago because until then, I'd been opting out of the scanner, and also had not been traveling so frequently.
I am fat.
I am a cis woman and present as such.

posted by rhiannonstone to Travel & Transportation (17 answers total)

Just to confirm, you've never had surgery on your left leg, ankle or foot?
posted by jeather at 5:26 PM on August 19, 2017

Response by poster: Correct, I've never had surgery or experienced any major injuries on my left leg, ankle, or foot.
posted by rhiannonstone at 5:28 PM on August 19, 2017

Are you right handed? A quick Google search indicates that an inside-left-ankle position is a common place to strap an ankle holster. So it might not be you, just a common place to focus during a patdown.
posted by peanut_mcgillicuty at 5:39 PM on August 19, 2017 [4 favorites]

If that kept happening to me the way it has happened to you, I would draw the conclusion that it was something idiosyncratic about the scanners rather than my ankle.
posted by ejs at 5:43 PM on August 19, 2017

I'm not an expert on scanners or tattoos, but the Wikipedia article mentions active scanners- they trigger when something is reflecting the energy they emit.

So something in the composition of the ink in your ankle tattoo is setting off the scanner, triggering your patdowns. Why the back one doesn't is a mystery to me, but if you research the types of ink used I strongly suspect that they are different.

https://en.m.wikipedia.org/wiki/Millimeter_wave_scanner
posted by Jacen at 5:45 PM on August 19, 2017 [15 favorites]

This happens to me (3/4 flights on my last trip). I don't have a tattoo or anything like that down there. Always the right ankle (I'm right handed).
posted by bradbane at 5:57 PM on August 19, 2017

I know this doesn't exactly answer the question, but if you're flying that much, it is worth considering TSA Pre, which would allow you to go through metal detectors instead of the body scanner. Bypass the hassle.
posted by primethyme at 6:04 PM on August 19, 2017 [3 favorites]

I think it's probably the tattoo. As far as I know, warm or sweaty places can light up on the scan- I've been patted down on my back and bra area on warm days when I've been rushing around and sweating. So an alternative could be some friction with your shoe or pant leg causing that area to warm up.
posted by emd3737 at 6:07 PM on August 19, 2017 [1 favorite]

Do you cuff your jeans at all? I have found I will ding if I have a wrap dress on where the fabric folds over multiple times.
posted by Suffocating Kitty at 6:10 PM on August 19, 2017

Seconding the jeans cuff question - or do you stand in such a way that your jeans bunch up around your left ankle? I get dinged when I wear my hair in a big bun - I think a lot of what the scanners are looking for is lumps and bumps.
posted by mskyle at 6:15 PM on August 19, 2017

this also happens to me every time i fly. same ankle. i do cuff my jeans, but only the left ankle triggers. it just happened last week, and the security line was dead, so the TSA agent struck up a conversation with me about it, and asked me if i'd had a previous ankle injury there. i've never had a serious one, but she said even minor swelling can trigger the scanner, and i'm a klutz so i do roll that ankle a lot. it's weird because when it flagged, my right ankle pant cuff was bigger than the left. so i do think it's fluid retention or puffiness or minimal scar tissue setting off the scanner. could be the same for you?
posted by halation at 8:41 PM on August 19, 2017 [5 favorites]

I don't have tattoos, nor do I cuff my pants, but show a positive every time in various places on my body. A TSA agent told me "we know why but we can't tell you "
posted by brujita at 9:09 PM on August 19, 2017 [2 favorites]

I suspect the tattoo, based on surveys I've taken before MRIs indicating that certain tattoo inks contain magnetic metals.

I have surgical screws in one of my ankles. Those have never set off the detectors.
posted by ktkt at 10:33 AM on August 20, 2017

This happens to me with my left hip pocket, and I don't know why, either. I suspect that I have slightly asymmetric muscles or an odd gait or something (I am right handed for most tasks and mixed-handed for some, plus I have a trick left knee) so I was just assuming it was a quirk of anatomy.
posted by blnkfrnk at 1:03 PM on August 20, 2017

This happens to me a lot. No tattoo or any injury, aside from a scar on the back of the right ankle where I had to have stitches, but they are as often patting down the left as the right. No jean cuffing, either, and it happens with different types of pants.
posted by Preserver at 8:29 AM on August 21, 2017

I don't fly often, but I had this happen both times I went through airport security last year. I was also in bootcut jeans (not cuffed). I am also fat, with large calves and ankles that are usually a bit puffy (the left more so than the right). I chalked it up to my ankles looking larger than expected and slightly uneven during the scan, so if the OP is rocking cankles like mine...
posted by QuickedWeen at 9:19 AM on August 21, 2017 [1 favorite]

A late response - I've actually just been travelling, so I have very recent experience with this. Going through the scanner I alerted and was patted down/swabbed etc. The area that showed up oddly on the scan was my butt/crotch area. I had absolutely nothing weird going on here - no belt, not so much as a paper in my pocket. The TSA agent told me that baggy pants often alert because of the extra fabric. I have recently lost a bit of weight and the butt of my jeans is slightly saggy, but I mean it's *slightly* saggy. I'm quite particular about the cut of my jeans and had just decided last week to purchase new jeans when I returned from my trip because I was starting to notice some minor wrinkling in the rear. So I guess quite a minor bit of excess fabric is enough to show up as an area of concern on the scanner. If I had to guess, in your case I would bet it's because you wear bootcut jeans and so have a bit of excess fabric around the lower leg, and when you stand in that strange spread-leg position they have to you take in the scanner you put more weight on one leg rather than the other, causing one pant leg to bunch up a tiny bit more than the other. Perhaps try to deliberately shift your weight to the other leg next time and see if you notice them going for the opposite ankle, in order to test the theory?
posted by DSime at 9:20 AM on August 22, 2017