On 11 September 2001, terrorists used airplanes to carry out acts of terrorism in the United States (US). Following these events, the Intelligence Reform and Terrorism Prevention Act of 2004 required the development of a no fly list. The purpose of this security measure was to help combat the threat of terrorism by keeping dangerous individuals off of airplanes. The constitutionality and the effectiveness of this list are subjects of controversy.
People who are on the no fly list are not allowed to board airplanes for domestic flights within the US. These individuals are also not allowed to board airplanes to leave the US. Furthermore, people whose names appear on this list are not allowed to fly into the US.
The exact number of names on the list is generally a matter of speculation. This information is not made public. People who are on the list are not notified and they have no way of knowing they are terrorist suspects. The inability to use automated check-in services that should otherwise be available may be an indication that a person’s name is listed, since individuals on the list are denied these privileges.
The Transportation Security Administration (TSA) claims that "The 'No-Fly' list has been an essential element of the aviation security — it keeps known terrorists off planes.” The American Civil Liberties Union (ACLU), which has already sued the US government with regards to the list, says it is inaccurate because “it is virtually impossible to know in advance whether a person is a terrorist.” There are no credible statistics to determine how effective the list truly is.
In addition to TSA, airlines also play a role in helping prevent people listed on the no fly list from boarding planes. When additions are made to the list, airlines should be notified. The US government requires airlines to check the updated list within two hours of being notified that changes have been made.
While the intentions behind the creation of the no fly list are generally believed to be positive, it has created some problems and drawn criticism. One problem with the no fly list is that innocent people can be detained, interrogated, or prevented from flying simply because their names raise concerns. Instances have been reported where small children were mistaken for people without flight privileges. The prevalence of this problem has led to the development of the Department of Homeland Security (DHS) Traveler Redress Inquiry Program (TRIP). This allows people who claim to be falsely affected by the fly list to apply to have the problem solved.