Which type of flight is indicated by the letter "B" in NORAD aircraft movement messages?

The designation indicated by the letter "B" in NORAD aircraft movement messages refers to "ACC tactical" flights. This classification is important as it identifies military aircraft that are engaged in tactical operations, often related to air defense and responsive actions within the NORAD framework. This context shows that these flights are typically associated with active military readiness and engagement in operations that may involve exercises, training, or direct response to potential threats.

In contrast, other types of flights such as General Aviation or Civil Aviation do not pertain to military operations and thus are not classified under NORAD's tactical framework. "NORAD Special Interest" also represents a different category that would involve specific monitoring of flights deemed to require closer observation, rather than the general tactical operations signified by "B." Understanding these classifications helps to differentiate the roles and missions of various flight operations within the NORAD airspace management strategy.