Explosive Tri-X!

[ZugPhoto]

So there I am at BWI Airport on the way to Las Vegas. In my Pelican was a Nikon F, a couple of lenses, and 2 rolls of Tri-X in a X-Ray proof bag. As expected, the person looking at the monitor calls for an inspection after seeing the bag. No problem.

So they do a swab on both rolls of Tri-X and one comes up indicating explosive residue. These were unopened canisters. They run the "explosive" one through the x-ray machine again and all is fine. While this is happening, I get the new TSA pat-down.

Everything turned out OK and the TSA folks were professional, courteous, and let me bore them to death about my '67 F after they asked about the "electronics" in them. I guess I'll start shooting with the roll they didn't run through X-ray again. My only question is what was on the Tri-X that set off the machine?

 

[rpsawin]

I had the same experience leaving from New Orleans. At that time the TSA guys thought maybe my gear bag/film picked up some gun shot residue (gsr for you csi nuts) when I was in the french quarter.

Best regards,

Bob

 

[Mainecoonmaniac]

Did you have Tri-X with the old nitrate base

 

[Kevin Kehler]

I got a rubber glove search at the airport once when my camera bag came up positive for nitroglycerin; turns out the silicon gel packs floating around in the bag had some kind of residue on them which tested positive. The security guys confiscated all the gel packs but held the flight so I could get on (with the cameras I might add). Those little back rooms are badly decorated.

 

[TheFlyingCamera]

See my thread about I hate to fly for another recent take on the "professionalism" of the TSA. If they can't tell the difference between mango chutney, baby food and nitroglycerine, I have absolutely no faith in their ability to keep me secure, and no desire to give them another opportunity to sexually fondle me in the name of "security".

 

[Sean]

Meanwhile as they scan your film, inspect your shoes and pat you down, a terrorist with a small block of C4 implanted in his abdomen strolls right through...

 

[Markster]

Stranger things have happened... Just ask Jeff Dunham:

http://www.youtube.com/watch?v=XgcrEhhiEhA

 

[Tom Stanworth]

Not long ago a swab on my camera bag came up positive for cocaine and that resulted in a LONG search. All sorts of rubbish ends up all over the place and security personnel have to follow the drills when they get a hit, even if they think it is farcical. I used to deal with security points doing that sort of swab testing and the endless hits were a real irritation.

 

[rpsawin]

Did you have Tri-X with the old nitrate base

Actually, I had two shieled bags containing a variety of Fuji chromes...no negative materials at all.

Bob

 

[lns]

I got swabbed, along with my then-9-year-old daughter, because her tube of toothpaste was too big. Luckily, we passed. But they still took the toothpaste.

They were very nice about the film, however, even though some of it was Tri-X.

"Farcical" is indeed the word for this. I guess in this economy we need all the jobs we can get, but ....

-Laura

 

[jp498]

I've got a bag I take to the shooting range and set it right on the shooting bench with everything else. I emptied the empty shells out of it and went flying with it. They swabbed it and didn't detect a thing.

Maybe it wasn't the tri-x but a quality control pre-spiked swab that management puts in to make sure they are doing their work and finding stuff? I lost my TSA instruction manual that got leaked to the web, but it probably doesn't cover that anyways.

 

[Mainecoonmaniac]

It's a photo geek joke

Actually, I had two shieled bags containing a variety of Fuji chromes...no negative materials at all.

Bob

I think when Tri-X was invented, nitrate based film was already phased out.

 

[removed account4]

every time i travel my photo-stuff
( film and cameras ) requires a swab
and then questions .. it's probably just
standard operating procedure to swab film
and cameras ... i don't really see what the problem is ...

 

[cmo]

I can unravel the mystery.

Today TSA uses ingenious technology. The alert went off, but not because of gunpowder traces on a film canister but because you had photographed a guy on your Tri-X who had used explosives recently... well, on Iwo Jima.

Don't tell the guys at the airport, their humour was removed by surgery. Or, if you insist on telling them, don't mention my name

Attention, underground marketing ahead:

Dead Link Removed

 

[msa]

What he said...it's not gunshot residue, they aren't even capable of detecting smokeless powder residue.

I regularly use the same backpack for travel as I do on the range, and have for years and years...it swabs clean.

 

[2F/2F]

Are you a smoker? Perhaps some flint or match residue or naptha from your lighter fluid found its way there.

 

[Rafal Lukawiecki]

When I was leaving from Cody airport, Wyoming, after a wonderful visit to Yellowstone in 2008, I requested a hand inspection of my boxed 4x5 negatives. The officers were very polite and obliged. With a corner of my eye, I noticed that a lady doing the inspection on another table was taking a swab, and it seemed to me, like she took a peek in the box. I quickly banished the thought - surely they would know about light-sensitive film, after all, I mentioned this was large format photographic film.

When I developed the negatives, I managed to salvage only the very few at the bottom of each pack. All the top ones were fully overexposed, and all of them had overexposed perimeters. The hand inspection was thorough, indeed.

This taught me never to ask for a hand inspection again, to tape my negative boxes shut using stronger tape, and to plan a return visit to Yellowstone.

 

[jp498]

Rafal, you have to watch them like a hawk when they have your stuff. They will try to distract you.

 

[michaelbsc]

...They will try to distract you.

Too much credit.

Some wag from years ago in the old Usenet News had a signature line that said, "Never attribute to malice that which is adequately explained by stupidity."

Or, as George Carlin used to say, "Think of how stupid the average person is, and realize half of them are stupider than that."

 

[Sirius Glass]

If you use Neosporin or Polysporin and the pack you bags, be prepared to have all your bags opened and every swabbed. This happened to me once and I only got on the plane because the pilot saw what was going on and he gave me permission to fly.

Steve

 

[John Shriver]

It's just "Security Theater". By maximally inconveniencing us, they look like they are being "tough on terrorism". The Europeans have had the right approach to terrorism for years -- be resilient and cope with it. The more you react, the more they get what they wanted.

Meanwhile, Delvonte Tisdale stowed away in the wheel-well of a commercial jet. Could have had a lot of explosives with him. The system is a farce. A shame it didn't work well enough to prevent his death. But it's all about elections, not results...

 

[michaelbsc]

It's just "Security Theater". By maximally inconveniencing us, they look like they are being "tough on terrorism". The Europeans have had the right approach to terrorism for years -- be resilient and cope with it. The more you react, the more they get what they wanted.

Meanwhile, Delvonte Tisdale stowed away in the wheel-well of a commercial jet. Could have had a lot of explosives with him. The system is a farce. A shame it didn't work well enough to prevent his death. But it's all about elections, not results...

Elections are all that matter to them. And they would love to do away with that farce.

We'll never be rid of career politicians until we make politics a less rewarding career.

 

[wblynch]

Elections are all that matter to them. And they would love to do away with that farce.

We'll never be rid of career politicians until we make politics a less rewarding career.

And change the way we vote. We vote for all the wrong reasons. (character? ha!) The best people for the office get run out because of a lurid affair or something of no real importance while the 'pros' rob us blind.

The next time I'm holding out on my vote until they promise more film !!

 

[ozphoto]

What gets me totally, is the LAG restrictions they put in place. The amount we are permitted to carry on board is a great deal more than the shoe bomber (who got all this rolling) had on him - 100ml of liquid allowed that will fit in a small 8"x8" (approx) bag. Hmm, if I can fit 5 bottles in that bag that's 500ml of nitro - more than enough to blow a small hole in a plane methinks??

After all, they don't actually test any of the LAG we carry on now do they.

 

[alanrockwood]

I assume that the airport screening test is a fairly simple one that performs some kind of measurement, and if the measurement exceeds a certain threshold value the result will be called "positive" and if it is below threshold it will be called "negative.

Nothing is perfect, so any type of test has a certain rate of false positives and false negatives. The rate of false positives and false negatives relates to how sensitive and specific the test is. (Actually, for convenience I am going to frame the discussion in terms of true positives and true negatives.) If the test catches all the true positive specimens and correctly labels them as "positive" then the test is highly sensitive. If it catches all the true negative specimens and correctly labels them as "negative" then the test is highly specific.

Generally speaking, a test can be tuned to make it more sensitive (it will always catch a positive) by lowering the decision threshold. (I am assuming that a high value represents a positive.) However, there is a trade off when you do this because the test then becomes less specific.

Conversely, if you set the decision point at a higher level you will never falsely classify something as negative (i.e. the test is specific) but you will miss a lot of the positives (you have lost sensitivity).

Thus, you can see there is a trade off between sensitivity and specificity. One of the tricks to testing is to pick the decision point so it best suits the purpose. Do you want to set the decision point low, so you catch most of the bomb-carrying passengers, but at the same time subject a lot of innocent people patdowns, or do you want to set the decision point high, so that very few innocent people are subjected to patdowns, but you let more of the bomb-carrying passenger through undetected. It presents a dilemma, especially if the quality of the test is not very high.

The quality of the test can be summarized in a graph called a "receiver operator characteristic", also called an ROC curve. This concept was formulated during war time to characterize the quality of radar operators in correctly classifying blips on radar.

Nowadays ROC curves are use a lot in characterizing the quality of clinical tests. An example of a test with a favorable ROC curve is troponin for diagnosing heart attack (myocardial infarction). An example of a test with a rather poor ROC curve is PSA for diagnosing prostate cancer.

One could go into other concepts like positive predictive value, negative predictive value, pretest odds, post test odds, likelyhood ratios, Bayes' theorem, and a lot of other related concepts, but it kind of makes my head hurt, even though I am supposed to know that stuff.

I just thought you might want to know that.