What letter signifies an ACC tactical flight in NORAD aircraft movement messages?

The letter that signifies an ACC tactical flight in NORAD aircraft movement messages is indeed B. In military aviation and air traffic control contexts, specific letters are designated to communicate critical information regarding the type of flight operations being carried out. ACC stands for Air Combat Command, and it relates to how units identify their operational status and type of missions they are executing. The use of the letter B in this context is standardized within the NORAD framework to ensure clear and efficient communication among various military branches and allied nations. This standardization enhances situational awareness and coordination during operations.

Other letters may refer to different types of flights or operational statuses, which is why they don't apply in this scenario. Each designation serves a specific purpose to streamline operations and enhance safety and efficiency in air command.