Tom Carpenter's Blog

So, I just passed through security at the Columbus, Ohio airport for the sixth or seventh time this year. Of my journeys through the TSA stalls in Columbus, I recall one time this year that I was not selected for a little extra patting, rubbing or travel bag exploration. In my opinion, this is where the problem with random screening rests.

If the TSA would only scan boarding passes as the passengers go through security, they could determine which passengers have been selected for "random" screening many times in the past and ensure that they are not wasting their time on the same person again and again. For example, I have a friend who flies frequently (3-4 times each month like me) and he said he has not been "randomly" selected once this year.

The biggest problem is that we're depending on extremely biased machines to randomize the passengers. These biased machines are also known as humans. Maybe one TSA agent always selects the person they feel will be most cooperative. Maybe they select every fifth person through to attempt pure randomization. Through observation tests, I can assure you that no such pattern is used even if they are told to use such a pattern. In one sixty minute period I observed 53 passengers going through security. No humanly trackable pattern appeared in the selection process.

However, one interesting pattern did appear. Of the 53 people passing through, 7 were selected for additional screening. Of the 53 passengers, 4 helped other people with an item that fell or some other needed assistance. Not one of these four people were selected.

This made me so curious that I had to do an experiment. While sitting at the Atlanta airport, where hundreds trudge through security each hour, I was able to observe a security lane where the "random selector" agent could clearly see everyone as they were preparing to come through. In just over two hours, I observed 27 people helping someone else through the line. Again, they were not selected for additional screening.

Now, clearly, further research is required to verify this bias, but the preliminary counts seem to indicate that you can greatly increase your odds of avoiding "random" selection by helping someone on the way through the line. And this is just one example of the bias within the human machine.

So, how do we fix this. Simple, an alternating pattern must be used to select the "random" passengers. Each TSA agent can be assigned a pattern (one could be the 3, 5, 2, 1, 7, 3, 5, 2, etc and another be 4, 5, 2, 5, 3, 2, 1, 4, 5, 2, 5, etc) and the "random selector" agent can be replaced with another agent after 3-4 iterations of the pattern making it difficult for pattern watchers to discover the pattern.

Additionally, to add variety to the pattern, if a passenger has been screened more than 3 of the last 5 times they've flown within the last sixty days, the agent is notified through a vibration signal with a hip mounted device. The agent simply passes over this passenger and continues his pattern with the next passenger. Of course, this would require boarding pass scanning outside of security, but maybe this would provide some real value at the point of entry in opposition to what we have now.

Now, I know what you're thinking, "Tom, this sounds too confusing." I say that the TSA agents are paid very well and we should not hesitate to require this ability and skill from them. Those who can't cut it, simply find themselves in lower paid positions, such as the non-observing guard at the exit of security.

In the end, random just ain't random when humans are involved and it can actually make for weakened security. Just a thought.

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Tags: physical security, security
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