Watch-list matching of passengers on large aircraft is an important security measure, because it can prevent individuals who are believed to pose a risk from boarding a large aircraft and, potentially, gaining control of the aircraft, to use it as a weapon. TSA studies have shown that significant loss of lives and other damage could result from such an incident.

When an aircraft operator receives passenger information that is similar to, or the same as, a name on the No Fly or Selectee List, the aircraft operator is required to notify law enforcement personnel and TSA in order to determine whether that passenger is in fact the individual listed on the No Fly or Selectee List. The aircraft operator may not board a passenger until TSA has instructed the aircraft operator that the passenger is clear to board the aircraft.