Which procedure is used to signal an emergency evacuation?

The correct procedure to signal an emergency evacuation is three long blasts of the air horn. This method is commonly used because it provides a clear and immediate auditory signal that can be easily recognized in high-stress situations, such as a fire or other emergency scenarios. The use of an air horn creates a distinctive sound that cuts through background noise, ensuring that individuals can hear the signal from a distance.

Other methods, such as continuous siren alerts or direct verbal communication, may not be as effective in a chaotic environment where visibility might be limited and voices could be drowned out by other sounds. Sequentially flashing lights could also be useful, but they rely on individuals being able to see the lights, which may not always be the case in smoke-filled or dark environments. Therefore, the standardized use of three long blasts of the air horn is a reliable and widely accepted practice for signaling an immediate evacuation. This protocol helps ensure the safety of all personnel by prompting an organized and prompt response.