Aviation security officers scan X-ray images of passengers’ property looking for prohibited items. They search for knifes, guns, bombs, and more. Threatening items can definitely come through a security checkpoint, and even very strange things might come through, however, only a small number of bags actually contain a real threat. Nearly all passengers are simply trying to travel safely and are not bringing prohibited items into the checkpoint environment.



The low number of surrenderable items is great for overall security and for the traveling public, but it is not ideal for keeping the screening workforce on their toes. In all likelihood, any given officer will never (thankfully) see a real bomb over the course of their entire career. But what does that do to their visual search skills? Will employees stop searching for threats with all of their effort if they never see any threats? Will they lose their vigilance if they aren’t seeing regular targets in their searches?


The Threat Image Projection (TIP) program can potentially help with these concerns. TIP involves projecting pictures of prohibited items into passengers’ bags at the checkpoint. These fake prohibited items are not actually put in the bag—it is just a picture combined with the X-ray image of the bag so that it should elicit a response from the security screener. The screener is given immediate feedback when a TIP image is included in the X-ray image of a passenger’s bag: if the officer correctly alarms that there is something in the bag, the TIP is highlighted and they are informed that it was a TIP image. The TIP is removed and the officer is then supposed to search the bag again. If the officer does not alarm to the TIP image, they received feedback about their mistake. These events are typically logged such that there is a record of each security officer’s successes and failures at finding the TIP images.


The potential concerns with TIP—making it an assessment undermines the entire system

While TIP can, and has, served as a useful tool to improve security officers’ vigilance for real threats, it inevitably is used as an assessment tool. Supervisors get monthly reports on each officer’s performance. For such a critical task that often lacks concrete ways to assess performance, this is too good to not use. Why not use the TIP data to get insight into who is doing well and who might not be searching as accurately as they should?


Sadly, using TIP as an assessment tool ruins it. The screening officer wants to find all threats…but a real threat is so rare that it is, for all intents and purposes, just not a real possibility. But TIP images are coming and the officer gets feedback on performance and their score is used as a measure of their place in the workforce. If you make a task a part of an employee’s evaluation process, then the employee is going to make sure they are great at that task. Story after story highlights how security officers change their behavior, “game” the system, focus on the wrong things, etc. just so they can improve their TIP scores. This is not what TIP is good for and by making TIP an assessment, the structure of it starts to fall apart.


It has been suggested that security officers will first search an X-ray image for a TIP and then they will search for real once they have decided if a TIP was present or not. That this occurs highlights the pitfalls of using TIP as an assessment because it adds a secondary, distracting task on top of the officers’ primary task—using the same screen, the same response buttons, and at the same time. As an analogy, imagine while you are driving your car down the street you are ALSO playing a driving video game where you use the steering wheel to control both your car and the videogame car, you use the windshield to watch the real road and the video game road, etc. That would be crazy—no one would ever try to use the same controls and same visual input to complete these two tasks at the exact same time. Unfortunately, that is what TIP is doing at the checkpoint when it is used as an assessment.


There are additional concerns for TIP—what happens if a TIP image is projected into a bag that actually contains a real prohibited item? This opens the door for “satisfaction of search” (aka subsequent search miss) errors—when one target is detected, additional targets in the same search are less likely to be found.



TIP is a powerful idea and can serve a very needed role in an airport security environment—give the officers experience seeing prohibited items that are rare and keep them on their toes. But TIP is a lousy assessment tool and using it to assess performance can have serious problems. It is vital to assess the screening workforce, but TIP is not the solution.



There needs to be a means to assess search performance in a way that provides concrete, objective data and that will not interfere with searching the normal stream of commerce at the checkpoint. One solution is to assess performance offline so that it cannot interfere with on-the-job performance like TIP currently does. Kedlin Screening International’s XRAY Screener tool has been shown to reliably relate to TIP scores, covert testing scores (accuracy at finding real threat brought through the checkpoint by plainclothes employees), and the speed of processing bags at the checkpoint. This work is published in a peer-reviewed paper, and suggests that XRAY Screener can be safely used as an assessment tool. A second solution builds on ideas around “remote screening”—having the screening officers away from the actual checkpoint. In such a setting, whole bag tests can be sent to the officers. This still interferes with passenger flow issues (adjudicating the fake bag takes time) but does not insert a fake image into a real bag.

This blog post is part of a series produced by Kedlin Screening International. Follow us on LinkedIn to see our other posts that will tackle a range of issues including: the science behind visual search, the pros and cons of workforce specialization, the pros and cons of remote screening, various factors that can make visual searches less successful, training vs. selection/allocation, and more.


At Kedlin Screening International, we understand the importance of visual search for security screening, and our focus is on using data-driven technology backed by science to help security organizations improve their operational efficiency and to increase their security effectiveness. We accomplish this mission by helping organizations find the right people to hire and then assessing and managing their workforce to maximize resources.


We’d love to hear from you, feel free to reach out to our team!


Steve Mitroff, Chief Science Officer

Ben Sharpe, CEO