What Do You Know About Capps?

How does CAPPS determine who is a security risk? Provide at least two examples

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,   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 plane tickets or board planes traveling in the United States, and to mitigate perceived threats.   CAPPS systems rely on what is known as a Passenger Name Record, often abbreviated 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.
Example 1
On September 11, 2001, 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.
All of the hijackers on American Airlines Flight 77 were CAPPS selectees, with Hani Hanjour, Khalid al-Mihdhar, and Majed Moqed chosen by the CAPPS criteria. Nawaf al-Hazmi and Salem al-Hazmi were selected because they did not provide adequate identification, and had their checked bags held until they boarded the aircraft.
Ahmad al-Haznawi was the only hijacker...