Computer Assisted Passenger Prescreening System

The Computer-Assisted Passenger Prescreening System (often abbreviated CAPPS) is a counter-terrorism system in place in the United States air travel industry. The United States Transportation Security Administration (TSA) maintains a watchlist, pursuant to 49 USC § 114 (h)(2), of "individuals known to pose, or suspected of posing, a risk of air piracy or terrorism or a threat to airline or passenger safety." The list is used to pre-emptively identify terrorists attempting to buy airline tickets or board aircraft traveling in the United States, and to mitigate perceived threats.

CAPPS systems rely on what is known as a passenger name record (PNR). When a person books a plane ticket, certain identifying information is collected by the airline: full name, address, etc. This information is used to check against some data store (e.g., a TSA No-Fly list, the FBI ten most wanted fugitive list, etc.) and assign a terrorism "risk score" to that person. High risk scores require the airline to subject the person to extended baggage and/or personal screening, and to contact law enforcement if necessary.

CAPPS I was first implemented in the late 1990s, in response to the perceived threat of U.S. domestic and international terrorism. CAPPS I was administered by the FBI and FAA. CAPPS screening selected passengers for additional screening of their checked baggage for explosives. CAPPS selectees did not undergo any additional screening at passenger security checkpoints.

On the morning of the September 11 attacks, several of the hijackers were selected by CAPPS. Wail al-Shehri, and Satam al-Suqami were selected for extra screening of their checked bags, before they boarded American Airlines Flight 11 at Logan International Airport. Waleed al-Shehri was also selected, but since he had checked no bags, CAPPS selection had no effect on him.Mohamed Atta was selected by CAPPS when he checked in at Portland International Jetport.

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