Final answer:
Armed Law Enforcement Officers (LEOs) must follow specific federal guidelines, keep their weapons concealed, and notify TSA of their armed status, especially if they've been in contact with radioactive substances and may set off radiation detectors.
Step-by-step explanation:
Proper procedures for armed Law Enforcement Officers (LEOs) at the airport and onboard an aircraft involve following specific federal guidelines. These guidelines are in place to ensure the safety and security of all passengers and the flight crew. LEOs must keep their identity and status as an armed officer confidential and should keep their weapons concealed at all times. In addition, they are required to notify the Transportation Security Administration (TSA) of their armed status. This is particularly important as they may set off radiation detectors due to potential recent contact with radioactive substances, such as those mentioned within the LibreTexts™ system reference. In such cases, they need to obtain special permission to fly on commercial flights.