Using risk-based security to quantify the number of firearms missed at airport security checkpoints

The Transportation Security Administration (TSA) is responsible for protecting the nation's air transportation system. Risk-based security is a paradigm for aligning security resources (i.e., personnel, technology, and time) with security risks. PreCheck is one approach that the TSA uses to implement this strategy. Given that passengers enrolled in PreCheck undergo background checks and fingerprinting, they experience expedited screening at airport security checkpoints, with standard screening lanes dedicated to passengers not enrolled in PreCheck. This difference can favorably impact the TSA's ability to detect threat items like firearms. This paper uses publicly available data on firearm detection, number of passengers screened, and the fraction of passenger screenings in PreCheck lanes to estimate the number of firearms missed at airport security checkpoints in the United States. To achieve this, it defines risky firearms as firearms carried by passengers not enrolled in PreCheck and assumes that only standard screening lanes are where such firearms are brought to checkpoints. Under this assumption, the number of risky firearms missed in the recent past is estimated, given more current risky firearm detection rates. This analysis suggests that increasing the number of PreCheck passenger screenings may reduce the number of undetected risky firearms passing through security checkpoints.