On September 11, 2006, the Federal Aviation Administration (FAA) issued Advisory Circular (AC) 90-103. (Search Advisory Circular database by AC number).

AC 90-103 will be of particular interest to aircrews who fly passengers in Part 135 or 121 operations. It defines four distinct passenger threat levels:  (1) disruptive, (2) abusive, (3) life-threatening, and (4) attempted/actual breach of the flight deck. The AC acknowledges that it would not be possible to provide guidance for every conceivable situation, but it attempts to define a Common Strategy or standardized approach for reporting such threats, as rapid exchange of information, in the event of multiple attacks, is paramount to ensure the integrity of the National Airspace System (NAS). Flight crew reports to the appropriate controlling ATC facility “should include level of interference, UTC, whether priority handling is requested, if the flight crew is requesting to divert due to the incident, a confirmation that the flight deck is secure, and any other information deemed necessary for ATC law enforcement, and other governmental action to safeguard the safety of aviation operations in the NAS.”